From 66ec9d9cc7b5480fdd27e4774f58cbe06d15fe7f Mon Sep 17 00:00:00 2001
From: sam2tom <sam2tom@users.noreply.github.com>
Date: Wed, 16 Sep 2026 13:41:17 +0800
Subject: [PATCH 1/3] feat(web): align Agents UI and Environment overview

---
 apps/web/e2e/agents-lifecycle.spec.ts         | 100 ++-
 apps/web/src/App.tsx                          | 118 +--
 apps/web/src/components/CreateMenu.test.tsx   |  24 +
 apps/web/src/components/CreateMenu.tsx        | 132 +++
 .../src/components/ProductNavigation.test.tsx |  18 +
 apps/web/src/components/ProductNavigation.tsx |  31 +
 apps/web/src/features/agents/AgentForm.tsx    | 113 ++-
 .../features/agents/AgentSetupView.test.tsx   |  50 ++
 .../src/features/agents/AgentSetupView.tsx    | 145 ++++
 apps/web/src/features/agents/AgentsView.tsx   |  80 +-
 .../src/features/agents/agent-form.test.ts    |  22 +-
 apps/web/src/features/agents/agent-form.ts    |  56 +-
 .../src/features/agents/agent-preview.test.ts |  46 ++
 apps/web/src/features/agents/agent-preview.ts |  76 ++
 .../environments/EnvironmentsView.test.tsx    | 112 +++
 .../environments/EnvironmentsView.tsx         | 171 ++++
 .../src/features/sessions/SessionsView.tsx    |  12 +
 apps/web/src/style.css                        | 766 ++++++++++++++++++
 docs/protocol-coverage.md                     |  21 +-
 19 files changed, 1989 insertions(+), 104 deletions(-)
 create mode 100644 apps/web/src/components/CreateMenu.test.tsx
 create mode 100644 apps/web/src/components/CreateMenu.tsx
 create mode 100644 apps/web/src/components/ProductNavigation.test.tsx
 create mode 100644 apps/web/src/components/ProductNavigation.tsx
 create mode 100644 apps/web/src/features/agents/AgentSetupView.test.tsx
 create mode 100644 apps/web/src/features/agents/AgentSetupView.tsx
 create mode 100644 apps/web/src/features/agents/agent-preview.test.ts
 create mode 100644 apps/web/src/features/agents/agent-preview.ts
 create mode 100644 apps/web/src/features/environments/EnvironmentsView.test.tsx
 create mode 100644 apps/web/src/features/environments/EnvironmentsView.tsx

diff --git a/apps/web/e2e/agents-lifecycle.spec.ts b/apps/web/e2e/agents-lifecycle.spec.ts
index e991d14..43316db 100644
--- a/apps/web/e2e/agents-lifecycle.spec.ts
+++ b/apps/web/e2e/agents-lifecycle.spec.ts
@@ -154,6 +154,8 @@ test("retrieves latest details and reuses a validated create/edit form", async (
   await name.fill("");
   await page.getByLabel("Instructions").fill("");
   await page.getByLabel("Metadata").fill('{"team":"acceptance"}');
+  await page.getByLabel("Reasoning effort").selectOption("");
+  await page.getByLabel("Reasoning summary").selectOption("");
   await page.getByRole("button", { name: "Save changes" }).click();
   await expect(page.getByRole("button", { name: "Edit" })).toBeFocused();
 
@@ -164,34 +166,57 @@ test("retrieves latest details and reuses a validated create/edit form", async (
     name: null,
     instructions: null,
     metadata: { team: "acceptance" },
+    reasoning: { effort: null, summary: null },
   });
   expect(browserErrors).toEqual([]);
 });
 
-test("supports keyboard creation, traps focus, and returns focus on Escape", async ({ page, request }) => {
+test("supports global Create keyboard navigation and consumes setup requests once", async ({ page, request }) => {
   await openAgents(page, request);
-  const trigger = page.getByRole("button", { name: "New Agent" });
-  await trigger.click();
+  const createMenu = page.getByRole("button", { name: "Create", exact: true });
+  await createMenu.focus();
+  await page.keyboard.press("Enter");
+  await expect(page.getByRole("menuitem", { name: /^Agent\b/ })).toBeFocused();
+  await page.keyboard.press("Escape");
+  await expect(createMenu).toBeFocused();
+  await page.keyboard.press("ArrowDown");
+  const createAgentItem = page.getByRole("menuitem", { name: /^Agent\b/ });
+  const startSessionItem = page.getByRole("menuitem", { name: /^Start Session\b/ });
+  await expect(createAgentItem).toBeFocused();
+  await page.keyboard.press("ArrowDown");
+  await expect(startSessionItem).toBeFocused();
+  await page.keyboard.press("ArrowUp");
+  await expect(createAgentItem).toBeFocused();
+  await page.keyboard.press("Enter");
   await expect(page.getByLabel("Name")).toBeFocused();
+  await expect(page.getByRole("heading", { name: "Request preview" })).toBeVisible();
 
-  const close = page.getByRole("button", { name: "Close dialog" });
-  await close.focus();
-  await page.keyboard.press("Shift+Tab");
-  await expect(page.getByRole("button", { name: "Create Agent" })).toBeFocused();
+  await page.getByRole("button", { name: "Sessions", exact: true }).click();
+  await page.getByRole("button", { name: "Agents", exact: true }).click();
+  await expect(page.getByRole("table", { name: "Agents" })).toBeVisible();
+  await expect(page.getByRole("heading", { name: "New Agent" })).toHaveCount(0);
 
-  await page.getByLabel("Name").focus();
-  await page.keyboard.press("Escape");
-  await expect(page.getByRole("dialog")).toHaveCount(0);
-  await expect(trigger).toBeFocused();
   const detailTrigger = page.getByRole("button", { name: /Open details for Lifecycle Agent/ });
   await detailTrigger.focus();
   await detailTrigger.evaluate((button) => button.click());
   await expect(page.getByRole("dialog").getByRole("heading", { name: "Lifecycle Agent", exact: true })).toBeVisible();
   await page.keyboard.press("Escape");
+  await expect(page.getByRole("dialog")).toHaveCount(0);
   await expect(detailTrigger).toBeFocused();
   await expect(page.locator(".modal-backdrop")).toHaveCount(0);
 
-  await trigger.click();
+  await createMenu.click();
+  await startSessionItem.click();
+  await expect(page.getByRole("dialog", { name: "Start an idle Session" })).toBeVisible();
+  await page.getByRole("dialog", { name: "Start an idle Session" }).getByRole("button", { name: "Cancel" }).click();
+  await expect(createMenu).toBeFocused();
+  await page.getByRole("button", { name: "Agents", exact: true }).click();
+  await page.getByRole("button", { name: "Sessions", exact: true }).click();
+  await expect(page.getByRole("dialog", { name: "Start an idle Session" })).toHaveCount(0);
+
+  await page.getByRole("button", { name: "Agents", exact: true }).click();
+  await createMenu.click();
+  await createAgentItem.click();
   const createMetadata = page.locator(".agent-metadata-input");
   const createName = page.locator('input[data-agent-initial-focus="true"]');
   await expect(createName).toBeFocused();
@@ -200,7 +225,20 @@ test("supports keyboard creation, traps focus, and returns focus on Escape", asy
   await expect(createName).toHaveValue("");
   await createName.focus();
   await page.keyboard.press("Enter");
-  await expect(page.getByRole("dialog")).toHaveCount(0);
+  await expect(page.getByRole("status")).toContainText("Agent definition saved as");
+
+  await createMenu.click();
+  await createAgentItem.click();
+  await expect(page.getByLabel("Name")).toHaveValue("");
+  await expect(page.getByLabel("Name")).toBeEnabled();
+  await expect(page.getByRole("status")).toHaveCount(0);
+  await page.getByRole("button", { name: "Back to Agents" }).click();
+  await expect(createMenu).toBeFocused();
+
+  const ledgerCreate = page.getByRole("button", { name: "New Agent" });
+  await ledgerCreate.click();
+  await page.getByRole("button", { name: "Back to Agents" }).click();
+  await expect(ledgerCreate).toBeFocused();
 
   const requests = await fixtureRequests(request);
   const creates = requests.filter((entry) => entry.method === "POST" && entry.path === "/v1/agents");
@@ -317,17 +355,37 @@ test("keeps the Agent ledger and dialogs usable at 390 px in light and dark mode
   expect(metrics.ledger?.right).toBeLessThanOrEqual(390);
   await attachScreenshot(page, testInfo, "narrow-light-agent-ledger");
 
-  await page.getByRole("button", { name: "New Agent" }).click();
-  const dialog = page.getByRole("dialog");
-  const box = await dialog.boundingBox();
+  await page.getByRole("button", { name: "Environments", exact: true }).click();
+  await expect(page.getByRole("heading", { name: "Environments Observed" })).toBeVisible();
+  const sessionsNavigation = page.getByRole("button", { name: "Sessions", exact: true });
+  await sessionsNavigation.click();
+  await expect(sessionsNavigation).toHaveAttribute("aria-current", "page");
+  await expect(page.locator(".session-page")).toBeVisible();
+  await page.getByRole("button", { name: "Agents", exact: true }).click();
+
+  const globalCreate = page.getByRole("button", { name: "Create", exact: true });
+  await globalCreate.click();
+  const createPanel = page.getByRole("menu", { name: "Create" });
+  await expect(createPanel).toBeVisible();
+  const createPanelBox = await createPanel.boundingBox();
+  expect(createPanelBox).not.toBeNull();
+  expect(createPanelBox?.x ?? -1).toBeGreaterThanOrEqual(0);
+  expect((createPanelBox?.x ?? 0) + (createPanelBox?.width ?? 0)).toBeLessThanOrEqual(390);
+  expect(await page.evaluate(() => document.documentElement.scrollWidth)).toBeLessThanOrEqual(390);
+  await createPanel.getByRole("menuitem", { name: /^Agent\b/ }).click();
+  const setup = page.locator(".agent-setup-page");
+  const box = await setup.boundingBox();
   expect(box).not.toBeNull();
   expect(box?.x ?? -1).toBeGreaterThanOrEqual(0);
   expect(box?.y ?? -1).toBeGreaterThanOrEqual(0);
-  expect((box?.x ?? 0) + (box?.width ?? 0)).toBeLessThanOrEqual(390);
-  expect((box?.y ?? 0) + (box?.height ?? 0)).toBeLessThanOrEqual(844);
-  await expect(page.getByRole("button", { name: "Create Agent" })).toBeInViewport();
-  await attachScreenshot(page, testInfo, "narrow-light-create-dialog");
-  await page.keyboard.press("Escape");
+  expect((box?.x ?? 0) + (box?.width ?? 0)).toBeLessThanOrEqual(390.5);
+  expect(await page.evaluate(() => document.documentElement.scrollWidth)).toBeLessThanOrEqual(390);
+  await expect(page.getByRole("button", { name: "Save Agent definition" })).toBeVisible();
+  await expect(page.getByRole("heading", { name: "Request preview" })).toBeVisible();
+  await expect(page.getByLabel("Text format")).toHaveValue("Text");
+  await attachScreenshot(page, testInfo, "narrow-light-agent-setup");
+  await page.getByRole("button", { name: "Back to Agents" }).click();
+  await expect(globalCreate).toBeFocused();
 
   await page.getByRole("button", { name: "Dark theme" }).click();
   await expect(page.locator("html")).toHaveAttribute("data-theme", "dark");
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index 5e3a667..b764183 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -1,9 +1,4 @@
-import {
-  Bot,
-  Layers3,
-  MessageSquare,
-  Settings2,
-} from "lucide-react";
+import { Layers3, Settings2 } from "lucide-react";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 
 import { AgentCoreError } from "@agents-core-web/agents-client";
@@ -20,6 +15,8 @@ import type {
 } from "@agents-core-web/agents-client";
 
 import { ConnectionModal } from "./components/ConnectionModal";
+import { CreateMenu } from "./components/CreateMenu";
+import { ProductNavigation, type ProductView } from "./components/ProductNavigation";
 import { StatusIcon } from "./components/StatusIcon";
 import { ThemeMenu } from "./components/ThemeMenu";
 import { useToast } from "./components/Toast";
@@ -31,6 +28,7 @@ import {
   requestAgentDetail,
   requestAgentUpdate,
 } from "./features/agents/agent-actions";
+import { EnvironmentsView } from "./features/environments/EnvironmentsView";
 import {
   SessionsView,
   type SessionDetailState,
@@ -99,7 +97,7 @@ import {
   waitForStreamReconnect,
 } from "./lib/stream-reconnect";
 
-type View = "sessions" | "agents" | "system";
+type View = ProductView | "system";
 
 interface StreamConnection {
   sessionId: string | null;
@@ -210,6 +208,10 @@ export function App() {
     () => new Map(),
   );
   const [busy, setBusy] = useState(false);
+  const [agentCreateRequest, setAgentCreateRequest] = useState<number | null>(null);
+  const [sessionCreateRequest, setSessionCreateRequest] = useState<number | null>(null);
+  const agentCreateSequenceRef = useRef(0);
+  const sessionCreateSequenceRef = useRef(0);
   const selectedIdRef = useRef<string | null>(selectedId);
   const sessionsRef = useRef<AgentSession[]>(sessions);
   const itemsSessionIdRef = useRef<string | null>(itemsSessionId);
@@ -841,9 +843,10 @@ export function App() {
 
   const createAgent = async (input: CreateAgentInput) => {
     const agent = await run(() => core.createAgent(input), "Agent created.");
-    if (!agent || coreGeneration !== connectionGenerationRef.current) return;
+    if (!agent || coreGeneration !== connectionGenerationRef.current) return undefined;
     agentCollectionRevisionRef.current += 1;
     setAgents((current) => [agent, ...current]);
+    return agent;
   };
 
   const retrieveAgent = async (agentId: string) => {
@@ -1117,11 +1120,25 @@ export function App() {
     setConnectionOpen(false);
   };
 
-  const navItems: Array<{ id: View; label: string; icon: typeof MessageSquare }> = [
-    { id: "sessions", label: "Sessions", icon: MessageSquare },
-    { id: "agents", label: "Agents", icon: Bot },
-    { id: "system", label: "Architecture", icon: Layers3 },
-  ];
+  const openAgentSetup = () => {
+    setView("agents");
+    agentCreateSequenceRef.current += 1;
+    setAgentCreateRequest(agentCreateSequenceRef.current);
+  };
+
+  const openSessionSetup = () => {
+    setView("sessions");
+    sessionCreateSequenceRef.current += 1;
+    setSessionCreateRequest(sessionCreateSequenceRef.current);
+  };
+
+  const consumeAgentCreateRequest = useCallback((request: number) => {
+    setAgentCreateRequest((current) => current === request ? null : current);
+  }, []);
+
+  const consumeSessionCreateRequest = useCallback((request: number) => {
+    setSessionCreateRequest((current) => current === request ? null : current);
+  }, []);
 
   return (
     <div className="app-shell">
@@ -1135,43 +1152,18 @@ export function App() {
           <span className="brand-name">Agents Core Web</span>
         </div>
 
-        <nav className="main-nav" aria-label="Primary navigation">
-          <p className="nav-label">Agent</p>
-          {navItems.slice(0, 2).map((item) => {
-            const Icon = item.icon;
-            return (
-              <button
-                type="button"
-                className={view === item.id ? "active" : ""}
-                key={item.id}
-                onClick={() => setView(item.id)}
-                aria-label={item.label}
-                aria-current={view === item.id ? "page" : undefined}
-              >
-                <Icon size={15} strokeWidth={1.5} />
-                <span>{item.label}</span>
-                {item.id === "sessions" && sessions.length ? <em>{sessions.length}</em> : null}
-              </button>
-            );
-          })}
-
+        <nav className="main-nav" aria-label="System navigation">
           <p className="nav-label">System</p>
-          {navItems.slice(2).map((item) => {
-            const Icon = item.icon;
-            return (
-              <button
-                type="button"
-                className={view === item.id ? "active" : ""}
-                key={item.id}
-                onClick={() => setView(item.id)}
-                aria-label={item.label}
-                aria-current={view === item.id ? "page" : undefined}
-              >
-                <Icon size={15} strokeWidth={1.5} />
-                <span>{item.label}</span>
-              </button>
-            );
-          })}
+          <button
+            type="button"
+            className={view === "system" ? "active" : ""}
+            onClick={() => setView("system")}
+            aria-label="Architecture"
+            aria-current={view === "system" ? "page" : undefined}
+          >
+            <Layers3 size={15} strokeWidth={1.5} />
+            <span>Architecture</span>
+          </button>
         </nav>
 
         <div className="sidebar-footer">
@@ -1196,6 +1188,18 @@ export function App() {
       </aside>
 
       <main className="app-main" id="main-content" tabIndex={-1}>
+        <header className="product-header">
+          <ProductNavigation
+            active={view === "system" ? null : view}
+            onSelect={(nextView) => setView(nextView)}
+          />
+          <CreateMenu
+            canCreateAgent={agentCollectionState === "ready" && !busy}
+            canStartSession={sessionCollectionState === "ready" && agents.length > 0 && !busy}
+            onCreateAgent={openAgentSetup}
+            onStartSession={openSessionSetup}
+          />
+        </header>
         <div className="page-transition" key={view}>
           {view === "sessions" ? (
             <SessionsView
@@ -1208,6 +1212,8 @@ export function App() {
               busy={busy}
               coreError={sessionCollectionError}
               coreState={sessionCollectionState}
+              createRequest={sessionCreateRequest ?? 0}
+              onCreateRequestConsumed={consumeSessionCreateRequest}
               detailError={detailError}
               detailState={detailState}
               turnError={turnError}
@@ -1233,10 +1239,14 @@ export function App() {
           ) : null}
           {view === "agents" ? (
             <AgentsView
+              key={`agents:${coreGeneration}`}
               agents={agents}
               busy={busy}
+              coreBaseUrl={connection.baseUrl}
               coreError={agentCollectionError}
               coreState={agentCollectionState}
+              createRequest={agentCreateRequest ?? 0}
+              onCreateRequestConsumed={consumeAgentCreateRequest}
               onCreate={createAgent}
               onDelete={deleteAgent}
               onRefresh={() => void refreshAgents()}
@@ -1245,6 +1255,16 @@ export function App() {
               onUpdate={updateAgent}
             />
           ) : null}
+          {view === "environments" ? (
+            <EnvironmentsView
+              sessions={sessions}
+              observations={environmentObservations}
+              onOpenSession={(sessionId) => {
+                setSelectedId(sessionId);
+                setView("sessions");
+              }}
+            />
+          ) : null}
           {view === "system" ? <SystemView /> : null}
         </div>
       </main>
diff --git a/apps/web/src/components/CreateMenu.test.tsx b/apps/web/src/components/CreateMenu.test.tsx
new file mode 100644
index 0000000..1c3d411
--- /dev/null
+++ b/apps/web/src/components/CreateMenu.test.tsx
@@ -0,0 +1,24 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import { CreateMenuContent } from "./CreateMenu";
+
+describe("Create menu", () => {
+  it("keeps supported actions separate from explicit Core-unavailable resources", () => {
+    const html = renderToStaticMarkup(
+      <CreateMenuContent
+        canCreateAgent
+        canStartSession
+        onCreateAgent={() => undefined}
+        onStartSession={() => undefined}
+      />,
+    );
+
+    expect(html).toContain('role="menu"');
+    expect(html).toContain("Environment template");
+    expect(html).toContain("Core exposes no template API");
+    expect(html).toContain("operator-owned, never browser-managed");
+    expect(html.match(/aria-disabled="true"/g)).toHaveLength(2);
+    expect(html).not.toContain("executor_token");
+  });
+});
diff --git a/apps/web/src/components/CreateMenu.tsx b/apps/web/src/components/CreateMenu.tsx
new file mode 100644
index 0000000..0e00a52
--- /dev/null
+++ b/apps/web/src/components/CreateMenu.tsx
@@ -0,0 +1,132 @@
+import {
+  Bot,
+  ChevronDown,
+  FileBox,
+  KeyRound,
+  MessageSquare,
+  Plus,
+} from "lucide-react";
+import { useEffect, useRef, useState, type KeyboardEvent } from "react";
+
+interface CreateMenuActions {
+  canCreateAgent: boolean;
+  canStartSession: boolean;
+  onCreateAgent: () => void;
+  onStartSession: () => void;
+}
+
+export function CreateMenuContent({
+  canCreateAgent,
+  canStartSession,
+  onCreateAgent,
+  onStartSession,
+}: CreateMenuActions) {
+  return (
+    <div className="create-menu-panel" role="menu" aria-label="Create">
+      <button type="button" role="menuitem" onClick={onCreateAgent} disabled={!canCreateAgent}>
+        <Bot size={16} strokeWidth={1.5} aria-hidden="true" />
+        <span><strong>Agent</strong><small>Save a reusable Agent definition</small></span>
+      </button>
+      <div className="create-menu-unavailable" role="menuitem" aria-disabled="true">
+        <FileBox size={16} strokeWidth={1.5} aria-hidden="true" />
+        <span><strong>Environment template</strong><small>Unavailable · Core exposes no template API</small></span>
+      </div>
+      <div className="create-menu-unavailable" role="menuitem" aria-disabled="true">
+        <KeyRound size={16} strokeWidth={1.5} aria-hidden="true" />
+        <span><strong>Environment key</strong><small>Unavailable · operator-owned, never browser-managed</small></span>
+      </div>
+      <button type="button" role="menuitem" onClick={onStartSession} disabled={!canStartSession}>
+        <MessageSquare size={16} strokeWidth={1.5} aria-hidden="true" />
+        <span>
+          <strong>Start Session</strong>
+          <small>{canStartSession ? "Choose a saved Agent" : "Requires a loaded saved Agent"}</small>
+        </span>
+      </button>
+    </div>
+  );
+}
+
+export function CreateMenu(actions: CreateMenuActions) {
+  const [open, setOpen] = useState(false);
+  const rootRef = useRef<HTMLDivElement>(null);
+  const triggerRef = useRef<HTMLButtonElement>(null);
+
+  useEffect(() => {
+    if (!open) return;
+    const closeOnOutsidePointer = (event: MouseEvent) => {
+      if (!rootRef.current?.contains(event.target as Node)) setOpen(false);
+    };
+    document.addEventListener("mousedown", closeOnOutsidePointer);
+    return () => document.removeEventListener("mousedown", closeOnOutsidePointer);
+  }, [open]);
+
+  const focusMenuItem = (edge: "first" | "last") => {
+    window.requestAnimationFrame(() => {
+      const items = rootRef.current?.querySelectorAll<HTMLButtonElement>('button[role="menuitem"]:not([disabled])');
+      const item = edge === "first" ? items?.[0] : items?.[items.length - 1];
+      item?.focus();
+    });
+  };
+
+  const onMenuKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
+    if (event.key === "Escape") {
+      event.preventDefault();
+      setOpen(false);
+      triggerRef.current?.focus();
+      return;
+    }
+    if (!["ArrowDown", "ArrowUp", "Home", "End"].includes(event.key)) return;
+    const items = Array.from(
+      rootRef.current?.querySelectorAll<HTMLButtonElement>('button[role="menuitem"]:not([disabled])') ?? [],
+    );
+    if (!items.length) return;
+    event.preventDefault();
+    if (event.key === "Home") return void items[0]?.focus();
+    if (event.key === "End") return void items[items.length - 1]?.focus();
+    const current = items.indexOf(document.activeElement as HTMLButtonElement);
+    const delta = event.key === "ArrowDown" ? 1 : -1;
+    items[(current + delta + items.length) % items.length]?.focus();
+  };
+
+  return (
+    <div className="create-menu" ref={rootRef} onKeyDown={onMenuKeyDown}>
+      <button
+        ref={triggerRef}
+        className="button primary create-menu-trigger"
+        type="button"
+        aria-haspopup="menu"
+        aria-expanded={open}
+        onClick={(event) => {
+          const nextOpen = !open;
+          setOpen(nextOpen);
+          if (nextOpen && event.detail === 0) focusMenuItem("first");
+        }}
+        onKeyDown={(event) => {
+          if (event.key !== "ArrowDown" && event.key !== "ArrowUp") return;
+          event.preventDefault();
+          setOpen(true);
+          focusMenuItem(event.key === "ArrowDown" ? "first" : "last");
+        }}
+      >
+        <Plus size={14} strokeWidth={1.8} aria-hidden="true" />
+        Create
+        <ChevronDown size={13} strokeWidth={1.5} aria-hidden="true" />
+      </button>
+      {open ? (
+        <CreateMenuContent
+          {...actions}
+          onCreateAgent={() => {
+            setOpen(false);
+            triggerRef.current?.focus();
+            actions.onCreateAgent();
+          }}
+          onStartSession={() => {
+            setOpen(false);
+            triggerRef.current?.focus();
+            actions.onStartSession();
+          }}
+        />
+      ) : null}
+    </div>
+  );
+}
diff --git a/apps/web/src/components/ProductNavigation.test.tsx b/apps/web/src/components/ProductNavigation.test.tsx
new file mode 100644
index 0000000..e93f695
--- /dev/null
+++ b/apps/web/src/components/ProductNavigation.test.tsx
@@ -0,0 +1,18 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import { ProductNavigation } from "./ProductNavigation";
+
+describe("Product navigation", () => {
+  it("exposes the three product destinations and current page", () => {
+    const html = renderToStaticMarkup(
+      <ProductNavigation active="environments" onSelect={() => undefined} />,
+    );
+
+    expect(html).toContain('aria-label="Agents product"');
+    expect(html).toContain("Agents");
+    expect(html).toContain("Environments");
+    expect(html).toContain("Sessions");
+    expect(html).toContain('aria-current="page"');
+  });
+});
diff --git a/apps/web/src/components/ProductNavigation.tsx b/apps/web/src/components/ProductNavigation.tsx
new file mode 100644
index 0000000..b312c13
--- /dev/null
+++ b/apps/web/src/components/ProductNavigation.tsx
@@ -0,0 +1,31 @@
+export type ProductView = "agents" | "environments" | "sessions";
+
+const productViews: Array<{ id: ProductView; label: string }> = [
+  { id: "agents", label: "Agents" },
+  { id: "environments", label: "Environments" },
+  { id: "sessions", label: "Sessions" },
+];
+
+export function ProductNavigation({
+  active,
+  onSelect,
+}: {
+  active: ProductView | null;
+  onSelect: (view: ProductView) => void;
+}) {
+  return (
+    <nav className="product-navigation" aria-label="Agents product">
+      {productViews.map((item) => (
+        <button
+          type="button"
+          className={active === item.id ? "active" : ""}
+          key={item.id}
+          onClick={() => onSelect(item.id)}
+          aria-current={active === item.id ? "page" : undefined}
+        >
+          {item.label}
+        </button>
+      ))}
+    </nav>
+  );
+}
diff --git a/apps/web/src/features/agents/AgentForm.tsx b/apps/web/src/features/agents/AgentForm.tsx
index 90b8818..7762040 100644
--- a/apps/web/src/features/agents/AgentForm.tsx
+++ b/apps/web/src/features/agents/AgentForm.tsx
@@ -13,12 +13,14 @@ import { validateAgentForm, valuesFromAgent } from "./agent-form";
 
 interface AgentFormProps {
   agent?: SavedAgent;
+  disabled?: boolean;
   formId: string;
   knownModels: string[];
-  onSubmit: (input: CreateAgentInput) => Promise<void>;
+  onDraftChange?: (values: ReturnType<typeof valuesFromAgent>) => void;
+  onSubmit: (input: CreateAgentInput) => Promise<unknown>;
 }
 
-export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormProps) {
+export function AgentForm({ agent, disabled = false, formId, knownModels, onDraftChange, onSubmit }: AgentFormProps) {
   const nameRef = useRef<HTMLInputElement>(null);
   const options = buildModelOptionGroups(
     knownModels,
@@ -34,6 +36,11 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
   const [customModel, setCustomModel] = useState(initialIsSuggested ? "" : initial.model);
   const [instructions, setInstructions] = useState(initial.instructions);
   const [metadata, setMetadata] = useState(initial.metadata);
+  const [reasoningEffort, setReasoningEffort] = useState(initial.reasoningEffort);
+  const [reasoningSummary, setReasoningSummary] = useState(initial.reasoningSummary);
+  const [serviceTier, setServiceTier] = useState(initial.serviceTier);
+  const [textFormat] = useState(initial.textFormat);
+  const [textVerbosity, setTextVerbosity] = useState(initial.textVerbosity);
   const [modelError, setModelError] = useState<string | null>(null);
   const [metadataError, setMetadataError] = useState<string | null>(null);
   const model = modelChoice === CUSTOM_MODEL_OPTION ? customModel : modelIdFromOption(modelChoice) ?? "";
@@ -43,9 +50,33 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
     return () => window.cancelAnimationFrame(frame);
   }, []);
 
+  useEffect(() => {
+    onDraftChange?.({
+      name,
+      model,
+      instructions,
+      metadata,
+      reasoningEffort,
+      reasoningSummary,
+      serviceTier,
+      textFormat,
+      textVerbosity,
+    });
+  }, [instructions, metadata, model, name, onDraftChange, reasoningEffort, reasoningSummary, serviceTier, textFormat, textVerbosity]);
+
   const submit = async (event: FormEvent) => {
     event.preventDefault();
-    const result = validateAgentForm({ name, model, instructions, metadata });
+    const result = validateAgentForm({
+      name,
+      model,
+      instructions,
+      metadata,
+      reasoningEffort,
+      reasoningSummary,
+      serviceTier,
+      textFormat,
+      textVerbosity,
+    }, agent ? "update" : "create");
     setModelError(result.modelError ?? null);
     setMetadataError(result.metadataError ?? null);
     if (!result.input) return;
@@ -54,6 +85,7 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
 
   return (
     <form id={formId} className="form-stack" onSubmit={(event) => void submit(event)} noValidate>
+      <fieldset className="agent-form-fields" disabled={disabled}>
       <label className="field">
         <span>Name</span>
         <input
@@ -64,6 +96,15 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
           data-agent-initial-focus="true"
         />
       </label>
+      <label className="field">
+        <span>Instructions</span>
+        <textarea
+          value={instructions}
+          onChange={(event) => setInstructions(event.target.value)}
+          placeholder="Describe how this Agent should work…"
+          rows={5}
+        />
+      </label>
       <div className="field">
         <label className="field-label" htmlFor={`${formId}-model`}>
           <span>Model</span>
@@ -117,15 +158,62 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
           Model choices are editable Web-side suggestions, not a discovered Core catalog. Saving <code>{model || "a model ID"}</code> does not prove the current executor can run it.
         </span>
       </div>
-      <label className="field">
-        <span>Instructions</span>
-        <textarea
-          value={instructions}
-          onChange={(event) => setInstructions(event.target.value)}
-          placeholder="Describe how this Agent should work…"
-          rows={5}
-        />
-      </label>
+      <section className="agent-form-section" aria-labelledby={`${formId}-generation-title`}>
+        <div className="agent-form-section-heading">
+          <h3 id={`${formId}-generation-title`}>Generation</h3>
+          <span>Saved configuration, not runtime discovery</span>
+        </div>
+        <div className="agent-form-grid">
+          <label className="field">
+            <span>Text format</span>
+            <input
+              value={textFormat.type === "text" ? "Text" : "JSON schema · preserved"}
+              readOnly
+              aria-describedby={`${formId}-text-format-help`}
+            />
+            <small id={`${formId}-text-format-help`}>
+              Displayed from the Agent contract. This Web preserves JSON schemas but does not edit them yet.
+            </small>
+          </label>
+          <label className="field">
+            <span>Reasoning effort</span>
+            <select value={reasoningEffort} onChange={(event) => setReasoningEffort(event.target.value as typeof reasoningEffort)}>
+              <option value="">Core default</option>
+              {(["none", "minimal", "low", "medium", "high", "xhigh", "max"] as const).map((value) => (
+                <option value={value} key={value}>{value}</option>
+              ))}
+            </select>
+          </label>
+          <label className="field">
+            <span>Text verbosity</span>
+            <select value={textVerbosity} onChange={(event) => setTextVerbosity(event.target.value as typeof textVerbosity)}>
+              {(["low", "medium", "high"] as const).map((value) => (
+                <option value={value} key={value}>{value}</option>
+              ))}
+            </select>
+          </label>
+          <label className="field">
+            <span>Reasoning summary</span>
+            <select value={reasoningSummary} onChange={(event) => setReasoningSummary(event.target.value as typeof reasoningSummary)}>
+              <option value="">Core default</option>
+              {(["concise", "detailed", "auto"] as const).map((value) => (
+                <option value={value} key={value}>{value}</option>
+              ))}
+            </select>
+          </label>
+          <label className="field">
+            <span>Service tier</span>
+            <select value={serviceTier} onChange={(event) => setServiceTier(event.target.value as typeof serviceTier)}>
+              {(["auto", "default", "flex", "priority", "fast"] as const).map((value) => (
+                <option value={value} key={value}>{value}</option>
+              ))}
+            </select>
+          </label>
+        </div>
+        <p className="agent-form-capability-note">
+          These fields are saved by Agent Core. The connected executor, model, and provider may support a narrower set; the first real Turn remains authoritative.
+        </p>
+      </section>
       <label className="field">
         <span>Metadata</span>
         <textarea
@@ -140,6 +228,7 @@ export function AgentForm({ agent, formId, knownModels, onSubmit }: AgentFormPro
         <small id={`${formId}-metadata-help`}>JSON object with string values only. Never store secrets in Agent metadata.</small>
         {metadataError ? <small className="field-error" id={`${formId}-metadata-error`} role="alert">{metadataError}</small> : null}
       </label>
+      </fieldset>
     </form>
   );
 }
diff --git a/apps/web/src/features/agents/AgentSetupView.test.tsx b/apps/web/src/features/agents/AgentSetupView.test.tsx
new file mode 100644
index 0000000..81f093e
--- /dev/null
+++ b/apps/web/src/features/agents/AgentSetupView.test.tsx
@@ -0,0 +1,50 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import { AgentSetupView } from "./AgentSetupView";
+
+describe("Agent setup page", () => {
+  it("renders a dedicated setup workflow and credential-safe request preview", () => {
+    const html = renderToStaticMarkup(
+      <AgentSetupView
+        actionError={null}
+        baseUrl="/v1"
+        busy={false}
+        knownModels={["provider/model"]}
+        onBack={() => undefined}
+        onCreate={async () => undefined}
+        onStartSession={() => undefined}
+      />,
+    );
+
+    expect(html).toContain('aria-label="Breadcrumb"');
+    expect(html).toContain("New Agent");
+    expect(html).toContain("Request preview");
+    expect(html).toContain("${AGENTS_CORE_API_KEY}");
+    expect(html).toContain("Get started creating an Agent");
+    expect(html).toContain("Text format");
+    expect(html).toContain("This Web preserves JSON schemas but does not edit them yet");
+    expect(html).toContain("Reasoning effort");
+    expect(html).toContain("Text verbosity");
+    expect(html.indexOf(">Name<")).toBeLessThan(html.indexOf(">Instructions<"));
+    expect(html.indexOf(">Instructions<")).toBeLessThan(html.indexOf(">Model<"));
+    expect(html).not.toContain("manual-token");
+  });
+
+  it("locks the submitted draft while Core creation is in flight", () => {
+    const html = renderToStaticMarkup(
+      <AgentSetupView
+        actionError={null}
+        baseUrl="/v1"
+        busy
+        knownModels={["provider/model"]}
+        onBack={() => undefined}
+        onCreate={async () => undefined}
+        onStartSession={() => undefined}
+      />,
+    );
+
+    expect(html).toContain('<fieldset class="agent-form-fields" disabled=""');
+    expect(html).toContain("Saving…");
+  });
+});
diff --git a/apps/web/src/features/agents/AgentSetupView.tsx b/apps/web/src/features/agents/AgentSetupView.tsx
new file mode 100644
index 0000000..0e3ec8c
--- /dev/null
+++ b/apps/web/src/features/agents/AgentSetupView.tsx
@@ -0,0 +1,145 @@
+import { Check, ChevronRight, Circle, Code2, MessageSquare } from "lucide-react";
+import { useState } from "react";
+
+import type { CreateAgentInput, SavedAgent } from "@agents-core-web/agents-client";
+
+import { AgentForm } from "./AgentForm";
+import { buildAgentRequestPreview } from "./agent-preview";
+import { valuesFromAgent } from "./agent-form";
+
+function AgentRequestPreview({
+  baseUrl,
+  values,
+}: {
+  baseUrl: string;
+  values: ReturnType<typeof valuesFromAgent>;
+}) {
+  const preview = buildAgentRequestPreview(values, baseUrl);
+  return (
+    <section className="agent-request-preview" aria-labelledby="agent-request-preview-title">
+      <header>
+        <Code2 size={15} strokeWidth={1.5} aria-hidden="true" />
+        <div>
+          <h2 id="agent-request-preview-title">Request preview</h2>
+          <p>Uses placeholders only. The connected Core credential is never read into this preview.</p>
+        </div>
+      </header>
+      <div className="agent-preview-block">
+        <span>curl</span>
+        <pre>{preview.curl}</pre>
+      </div>
+      <div className="agent-preview-block">
+        <span>agent.json</span>
+        <pre>{preview.json}</pre>
+      </div>
+    </section>
+  );
+}
+
+function SetupGuide({ saved }: { saved: boolean }) {
+  const steps = [
+    ["Define an Agent", "Choose a model, instructions, and supported generation settings.", true],
+    ["Save the definition", "Core becomes the durable source of truth for the saved Agent.", saved],
+    ["Start a Session", "Create an idle environment:none Session and subscribe before sending input.", false],
+    ["Exchange events", "A real Turn still requires a compatible worker, executor, model, and provider.", false],
+  ] as const;
+  return (
+    <section className="agent-setup-guide" aria-labelledby="agent-setup-guide-title">
+      <h2 id="agent-setup-guide-title">Get started creating an Agent</h2>
+      <ol>
+        {steps.map(([title, description, complete]) => (
+          <li className={complete ? "complete" : ""} key={title}>
+            {complete ? <Check size={13} aria-hidden="true" /> : <Circle size={10} aria-hidden="true" />}
+            <div><strong>{title}</strong><span>{description}</span></div>
+          </li>
+        ))}
+      </ol>
+    </section>
+  );
+}
+
+export function AgentSetupView({
+  actionError,
+  baseUrl,
+  busy,
+  knownModels,
+  onBack,
+  onCreate,
+  onStartSession,
+}: {
+  actionError: string | null;
+  baseUrl: string;
+  busy: boolean;
+  knownModels: string[];
+  onBack: () => void;
+  onCreate: (input: CreateAgentInput) => Promise<SavedAgent | undefined>;
+  onStartSession: (agentId: string) => void;
+}) {
+  const [draft, setDraft] = useState(() => valuesFromAgent());
+  const [created, setCreated] = useState<SavedAgent | null>(null);
+  const formId = "create-agent";
+
+  const create = async (input: CreateAgentInput) => {
+    const agent = await onCreate(input);
+    if (agent) setCreated(agent);
+  };
+
+  return (
+    <section className="page-section agent-setup-page">
+      <header className="agent-setup-header">
+        <div className="agent-setup-breadcrumb" aria-label="Breadcrumb">
+          <button type="button" onClick={onBack}>Agents</button>
+          <ChevronRight size={14} aria-hidden="true" />
+          <h1>{created?.name || "New Agent"}</h1>
+        </div>
+        <div className="agent-setup-tabs" role="tablist" aria-label="Agent setup sections">
+          <button type="button" role="tab" aria-selected="true">Setup</button>
+          <button type="button" role="tab" aria-selected="false" disabled title="Session history is available from the Sessions product view">Sessions</button>
+        </div>
+      </header>
+
+      <div className="agent-setup-layout">
+        <section className="agent-setup-editor" aria-label="Agent definition">
+          {actionError ? (
+            <div className="agent-action-error" role="alert">
+              <strong>Request failed</strong><span>{actionError}</span>
+            </div>
+          ) : null}
+          {created ? (
+            <div className="notice success agent-created-notice" role="status">
+              <Check size={14} aria-hidden="true" />
+              Agent definition saved as <code>{created.id}</code>. This does not prove execution readiness.
+            </div>
+          ) : null}
+          <AgentForm
+            disabled={busy || Boolean(created)}
+            formId={formId}
+            knownModels={knownModels}
+            onDraftChange={setDraft}
+            onSubmit={create}
+          />
+          <footer className="agent-setup-actions">
+            <button className="button outline" type="button" onClick={onBack} disabled={busy}>Back to Agents</button>
+            <button className="button primary" type="submit" form={formId} disabled={busy || Boolean(created)}>
+              {busy ? "Saving…" : created ? "Agent saved" : "Save Agent definition"}
+            </button>
+            <button
+              className="button primary agent-start-session"
+              type="button"
+              disabled={busy || !created}
+              onClick={() => created && onStartSession(created.id)}
+            >
+              <MessageSquare size={14} strokeWidth={1.5} aria-hidden="true" />
+              Start Session
+            </button>
+          </footer>
+        </section>
+
+        <aside className="agent-setup-aside">
+          <AgentRequestPreview baseUrl={baseUrl} values={draft} />
+          <SetupGuide saved={Boolean(created)} />
+        </aside>
+      </div>
+    </section>
+  );
+}
diff --git a/apps/web/src/features/agents/AgentsView.tsx b/apps/web/src/features/agents/AgentsView.tsx
index 6a1751c..828ee37 100644
--- a/apps/web/src/features/agents/AgentsView.tsx
+++ b/apps/web/src/features/agents/AgentsView.tsx
@@ -8,14 +8,18 @@ import { Skeleton } from "../../components/Skeleton";
 import type { CoreConnectionState } from "../../lib/connection";
 import { AgentDialog } from "./AgentDialog";
 import { AgentForm } from "./AgentForm";
+import { AgentSetupView } from "./AgentSetupView";
 import { createRequestGate } from "./agent-form";
 
 interface AgentsViewProps {
   agents: SavedAgent[];
   busy: boolean;
+  coreBaseUrl?: string;
   coreError: string | null;
   coreState: CoreConnectionState;
-  onCreate: (input: CreateAgentInput) => Promise<void>;
+  createRequest?: number;
+  onCreateRequestConsumed?: (request: number) => void;
+  onCreate: (input: CreateAgentInput) => Promise<SavedAgent | undefined>;
   onDelete?: (agentId: string) => Promise<void>;
   onRefresh: () => void;
   onRetrieve?: (agentId: string) => Promise<SavedAgent | undefined>;
@@ -106,8 +110,11 @@ export function AgentDeleteConfirmation({ agent }: { agent: SavedAgent }) {
 export function AgentsView({
   agents,
   busy,
+  coreBaseUrl = "/v1",
   coreError,
   coreState,
+  createRequest = 0,
+  onCreateRequestConsumed,
   onCreate,
   onDelete,
   onRefresh,
@@ -120,9 +127,12 @@ export function AgentsView({
   const [detailLoading, setDetailLoading] = useState(false);
   const [actionError, setActionError] = useState<string | null>(null);
   const [query, setQuery] = useState("");
+  const [createSetupRevision, setCreateSetupRevision] = useState(0);
   const requestGate = useRef(createRequestGate());
   const detailActionRef = useRef<HTMLButtonElement>(null);
+  const createReturnFocusRef = useRef<HTMLElement | null>(null);
   const restoreDetailFocus = useRef(false);
+  const lastCreateRequestRef = useRef(0);
   const knownModels = agents.map((agent) => agent.model);
   const normalizedQuery = query.trim().toLowerCase();
   const filteredAgents = normalizedQuery
@@ -138,6 +148,27 @@ export function AgentsView({
     setDetailLoading(false);
   };
 
+  const closeCreateSetup = () => {
+    const returnFocus = createReturnFocusRef.current;
+    createReturnFocusRef.current = null;
+    closeDialog();
+    window.requestAnimationFrame(() => {
+      if (returnFocus?.isConnected) {
+        returnFocus.focus();
+        return;
+      }
+      document.querySelector<HTMLButtonElement>('button[data-create-agent-entry="true"]')?.focus();
+    });
+  };
+
+  const openCreateSetup = (returnFocus: HTMLElement | null) => {
+    requestGate.current.invalidate();
+    createReturnFocusRef.current = returnFocus;
+    setActionError(null);
+    setCreateSetupRevision((current) => current + 1);
+    setMode("create");
+  };
+
   const returnToDetail = () => {
     if (busy) return;
     requestGate.current.invalidate();
@@ -156,6 +187,17 @@ export function AgentsView({
     return () => window.cancelAnimationFrame(frame);
   }, [busy, detailLoading, mode, selectedAgent]);
 
+  useEffect(() => {
+    if (!createRequest || createRequest === lastCreateRequestRef.current) return;
+    lastCreateRequestRef.current = createRequest;
+    requestGate.current.invalidate();
+    createReturnFocusRef.current = document.activeElement instanceof HTMLElement ? document.activeElement : null;
+    setActionError(null);
+    setCreateSetupRevision((current) => current + 1);
+    setMode("create");
+    onCreateRequestConsumed?.(createRequest);
+  }, [createRequest, onCreateRequestConsumed]);
+
   const retrieve = async (agent: SavedAgent) => {
     const request = requestGate.current.begin();
     restoreDetailFocus.current = false;
@@ -179,10 +221,11 @@ export function AgentsView({
     const request = requestGate.current.begin();
     setActionError(null);
     try {
-      await onCreate(input);
-      if (requestGate.current.isCurrent(request)) closeDialog();
+      const created = await onCreate(input);
+      return requestGate.current.isCurrent(request) ? created : undefined;
     } catch (error) {
       if (requestGate.current.isCurrent(request)) setActionError(errorMessage(error));
+      return undefined;
     }
   };
 
@@ -227,7 +270,22 @@ export function AgentsView({
       : mode === "delete"
         ? "Delete Agent?"
         : selectedAgent?.name || "Agent details";
-  const formId = mode === "create" ? "create-agent" : "edit-agent";
+
+  if (mode === "create") {
+    return (
+      <AgentSetupView
+        key={createSetupRevision}
+        actionError={actionError}
+        baseUrl={coreBaseUrl}
+        busy={busy}
+        knownModels={knownModels}
+        onBack={closeCreateSetup}
+        onCreate={submitCreate}
+        onStartSession={startSession}
+      />
+    );
+  }
+  const formId = "edit-agent";
 
   return (
     <section className="page-section agents-page">
@@ -248,7 +306,7 @@ export function AgentsView({
           <button className="icon-button outline" type="button" onClick={onRefresh} disabled={coreState === "connecting"} aria-label="Refresh Agents">
             <RefreshCw className={coreState === "connecting" ? "refresh-spinning" : undefined} size={14} strokeWidth={1.5} />
           </button>
-          <button className="button primary" type="button" onClick={() => { requestGate.current.invalidate(); setActionError(null); setMode("create"); }} disabled={busy || coreState !== "ready"}>
+          <button data-create-agent-entry="true" className="button primary" type="button" onClick={(event) => openCreateSetup(event.currentTarget)} disabled={busy || coreState !== "ready"}>
             <Plus size={14} strokeWidth={1.5} /> New Agent
           </button>
         </div>
@@ -319,7 +377,7 @@ export function AgentsView({
           {agents.length ? (
             <button className="button outline" type="button" onClick={() => setQuery("")}>Clear search</button>
           ) : (
-            <button className="button primary" type="button" onClick={() => { requestGate.current.invalidate(); setMode("create"); }} disabled={busy}>Create Agent</button>
+            <button data-create-agent-entry="true" className="button primary" type="button" onClick={(event) => openCreateSetup(event.currentTarget)} disabled={busy}>Create Agent</button>
           )}
         </div>
       ) : null}
@@ -328,11 +386,11 @@ export function AgentsView({
         open={mode !== "closed"}
         onClose={closeDialog}
         title={dialogTitle}
-        footer={mode === "create" || mode === "edit" ? (
+        footer={mode === "edit" ? (
           <>
-            <button key="cancel-form" className="button outline" type="button" onClick={mode === "edit" ? returnToDetail : closeDialog} disabled={mode === "edit" && busy}>Cancel</button>
+            <button key="cancel-form" className="button outline" type="button" onClick={returnToDetail} disabled={busy}>Cancel</button>
             <button key="submit-form" className="button primary" type="submit" form={formId} disabled={busy}>
-              {busy ? (mode === "create" ? "Creating…" : "Saving…") : (mode === "create" ? "Create Agent" : "Save changes")}
+              {busy ? "Saving…" : "Save changes"}
             </button>
           </>
         ) : mode === "detail" ? (
@@ -360,9 +418,7 @@ export function AgentsView({
             {mode === "detail" && selectedAgent ? <button className="button outline" type="button" onClick={() => void retrieve(selectedAgent)}>Retry latest Agent</button> : null}
           </div>
         ) : null}
-        {mode === "create" ? (
-          <AgentForm formId={formId} knownModels={knownModels} onSubmit={submitCreate} />
-        ) : mode === "edit" && selectedAgent ? (
+        {mode === "edit" && selectedAgent ? (
           <AgentForm key={`${selectedAgent.id}:${selectedAgent.updated_at}`} agent={selectedAgent} formId={formId} knownModels={knownModels} onSubmit={submitUpdate} />
         ) : mode === "delete" && selectedAgent ? (
           <AgentDeleteConfirmation agent={selectedAgent} />
diff --git a/apps/web/src/features/agents/agent-form.test.ts b/apps/web/src/features/agents/agent-form.test.ts
index a5afe04..89383e4 100644
--- a/apps/web/src/features/agents/agent-form.test.ts
+++ b/apps/web/src/features/agents/agent-form.test.ts
@@ -5,6 +5,7 @@ import { createRequestGate, validateAgentForm, valuesFromAgent } from "./agent-f
 describe("Agent form contract", () => {
   it("uses explicit nulls for blank nullable fields and preserves string metadata", () => {
     const result = validateAgentForm({
+      ...valuesFromAgent(),
       model: "  provider/model  ",
       name: "   ",
       instructions: "",
@@ -17,6 +18,9 @@ describe("Agent form contract", () => {
         name: null,
         instructions: null,
         metadata: { team: "web", owner: "sam" },
+        reasoning: { effort: "medium", summary: "auto" },
+        service_tier: "auto",
+        text: { format: { type: "text" }, verbosity: "medium" },
       },
     });
   });
@@ -27,7 +31,7 @@ describe("Agent form contract", () => {
     ['{"retries":3}', "Every metadata value must be a string."],
     ['{"enabled":true}', "Every metadata value must be a string."],
   ])("rejects unsafe or unsupported metadata %s", (metadata, message) => {
-    expect(validateAgentForm({ model: "model", name: "", instructions: "", metadata })).toEqual({
+    expect(validateAgentForm({ ...valuesFromAgent(), model: "model", name: "", instructions: "", metadata })).toEqual({
       metadataError: message,
     });
   });
@@ -52,9 +56,25 @@ describe("Agent form contract", () => {
       model: "model",
       instructions: "",
       metadata: '{\n  "scope": "test"\n}',
+      reasoningEffort: "",
+      reasoningSummary: "",
+      serviceTier: "auto",
+      textFormat: { type: "text" },
+      textVerbosity: "medium",
     });
   });
 
+  it("explicitly clears reasoning defaults during an update instead of preserving stale values", () => {
+    const result = validateAgentForm({
+      ...valuesFromAgent(),
+      model: "provider/model",
+      reasoningEffort: "",
+      reasoningSummary: "",
+    }, "update");
+
+    expect(result.input?.reasoning).toEqual({ effort: null, summary: null });
+  });
+
   it("rejects an older detail response after a newer request or dialog close", () => {
     const gate = createRequestGate();
     const first = gate.begin();
diff --git a/apps/web/src/features/agents/agent-form.ts b/apps/web/src/features/agents/agent-form.ts
index e35ad28..4a82070 100644
--- a/apps/web/src/features/agents/agent-form.ts
+++ b/apps/web/src/features/agents/agent-form.ts
@@ -1,10 +1,24 @@
-import type { CreateAgentInput, SavedAgent } from "@agents-core-web/agents-client";
+import type {
+  AgentReasoningEffort,
+  AgentReasoningSummary,
+  AgentServiceTier,
+  AgentTextFormat,
+  CreateAgentInput,
+  SavedAgent,
+} from "@agents-core-web/agents-client";
+
+export type TextVerbosity = "low" | "medium" | "high";
 
 export interface AgentFormValues {
   name: string;
   model: string;
   instructions: string;
   metadata: string;
+  reasoningEffort: AgentReasoningEffort | "";
+  reasoningSummary: AgentReasoningSummary | "";
+  serviceTier: AgentServiceTier;
+  textFormat: AgentTextFormat;
+  textVerbosity: TextVerbosity;
 }
 
 export interface AgentFormValidation {
@@ -13,16 +27,26 @@ export interface AgentFormValidation {
   modelError?: string;
 }
 
+export type AgentFormIntent = "create" | "update";
+
 export function valuesFromAgent(agent?: SavedAgent): AgentFormValues {
   return {
     name: agent?.name ?? "",
     model: agent?.model ?? "",
     instructions: agent?.instructions ?? "",
     metadata: JSON.stringify(agent?.metadata ?? {}, null, 2),
+    reasoningEffort: agent ? agent.reasoning.effort ?? "" : "medium",
+    reasoningSummary: agent ? agent.reasoning.summary ?? "" : "auto",
+    serviceTier: agent?.service_tier ?? "auto",
+    textFormat: agent?.text.format ?? { type: "text" },
+    textVerbosity: agent?.text.verbosity ?? "medium",
   };
 }
 
-export function validateAgentForm(values: AgentFormValues): AgentFormValidation {
+export function validateAgentForm(
+  values: AgentFormValues,
+  intent: AgentFormIntent = "create",
+): AgentFormValidation {
   const model = values.model.trim();
   if (!model) return { modelError: "Enter a model ID." };
 
@@ -42,14 +66,30 @@ export function validateAgentForm(values: AgentFormValues): AgentFormValidation
     return { metadataError: "Every metadata value must be a string." };
   }
 
-  return {
-    input: {
-      model,
-      name: values.name.trim() || null,
-      instructions: values.instructions.trim() || null,
-      metadata: metadata as Record<string, string>,
+  const input: CreateAgentInput = {
+    model,
+    name: values.name.trim() || null,
+    instructions: values.instructions.trim() || null,
+    metadata: metadata as Record<string, string>,
+    service_tier: values.serviceTier,
+    text: {
+      format: values.textFormat,
+      verbosity: values.textVerbosity,
     },
   };
+  if (intent === "update") {
+    input.reasoning = {
+      effort: values.reasoningEffort || null,
+      summary: values.reasoningSummary || null,
+    };
+  } else if (values.reasoningEffort || values.reasoningSummary) {
+    input.reasoning = {
+      ...(values.reasoningEffort ? { effort: values.reasoningEffort } : {}),
+      ...(values.reasoningSummary ? { summary: values.reasoningSummary } : {}),
+    };
+  }
+
+  return { input };
 }
 
 export interface RequestGate {
diff --git a/apps/web/src/features/agents/agent-preview.test.ts b/apps/web/src/features/agents/agent-preview.test.ts
new file mode 100644
index 0000000..f958e48
--- /dev/null
+++ b/apps/web/src/features/agents/agent-preview.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it } from "vitest";
+
+import { buildAgentRequestPreview, previewTokenPlaceholder } from "./agent-preview";
+import { valuesFromAgent } from "./agent-form";
+
+describe("Agent request preview", () => {
+  it("uses only a documented placeholder and a separate JSON body", () => {
+    const preview = buildAgentRequestPreview({
+      ...valuesFromAgent(),
+      model: "provider/model",
+      name: "Builder",
+    }, "https://core.example/v1");
+
+    expect(preview.curl).toContain("https://core.example/v1/agents");
+    expect(preview.curl).toContain(previewTokenPlaceholder);
+    expect(preview.curl).toContain("@agent.json");
+    expect(preview.curl).not.toContain("live-caller-secret");
+    expect(JSON.parse(preview.json)).toMatchObject({
+      model: "provider/model",
+      reasoning: { effort: "medium", summary: "auto" },
+      text: { format: { type: "text" }, verbosity: "medium" },
+    });
+  });
+
+  it("does not echo unsafe URL credentials or query values", () => {
+    const preview = buildAgentRequestPreview(
+      valuesFromAgent(),
+      "https://user:live-caller-secret@core.example/v1?token=live-caller-secret",
+    );
+
+    expect(preview.curl).toContain("${AGENTS_CORE_BASE_URL}/agents");
+    expect(preview.curl).not.toContain("live-caller-secret");
+    expect(preview.curl).not.toContain("user:");
+  });
+
+  it("single-quotes a direct Core URL so copied shell commands cannot expand its path", () => {
+    const preview = buildAgentRequestPreview(
+      valuesFromAgent(),
+      "https://core.example/$(id)/a'b",
+    );
+
+    expect(preview.curl.split("\n")[0]).toBe(
+      `curl --request POST 'https://core.example/$(id)/a'"'"'b/agents' \\`,
+    );
+  });
+});
diff --git a/apps/web/src/features/agents/agent-preview.ts b/apps/web/src/features/agents/agent-preview.ts
new file mode 100644
index 0000000..60871fe
--- /dev/null
+++ b/apps/web/src/features/agents/agent-preview.ts
@@ -0,0 +1,76 @@
+import type { CreateAgentInput } from "@agents-core-web/agents-client";
+
+import type { AgentFormValues } from "./agent-form";
+import { validateAgentForm } from "./agent-form";
+
+export const previewTokenPlaceholder = "${AGENTS_CORE_API_KEY}";
+
+function shellSingleQuote(value: string): string {
+  return `'${value.replaceAll("'", `'"'"'`)}'`;
+}
+
+function previewEndpointArgument(baseUrl: string): string {
+  const candidate = (baseUrl.trim() || "/v1").replace(/\/+$/, "");
+  if (candidate === "/v1") {
+    return '"${AGENTS_CORE_BASE_URL:-http://127.0.0.1:8091/v1}/agents"';
+  }
+  try {
+    const url = new URL(candidate);
+    if (url.username || url.password || url.search || url.hash || !["http:", "https:"].includes(url.protocol)) {
+      return '"${AGENTS_CORE_BASE_URL}/agents"';
+    }
+    return shellSingleQuote(`${url.toString().replace(/\/+$/, "")}/agents`);
+  } catch {
+    return '"${AGENTS_CORE_BASE_URL}/agents"';
+  }
+}
+
+function safeMetadata(value: string): Record<string, string> {
+  try {
+    const parsed: unknown = value.trim() ? JSON.parse(value) : {};
+    if (
+      parsed &&
+      !Array.isArray(parsed) &&
+      typeof parsed === "object" &&
+      Object.values(parsed).every((entry) => typeof entry === "string")
+    ) return parsed as Record<string, string>;
+  } catch {
+    // The preview stays structurally valid while the form reports the parse error.
+  }
+  return {};
+}
+
+export function agentInputForPreview(values: AgentFormValues): CreateAgentInput {
+  const validated = validateAgentForm(values).input;
+  if (validated) return validated;
+
+  const input: CreateAgentInput = {
+    model: values.model.trim() || "<model-id>",
+    name: values.name.trim() || null,
+    instructions: values.instructions.trim() || null,
+    metadata: safeMetadata(values.metadata),
+    service_tier: values.serviceTier,
+    text: { format: values.textFormat, verbosity: values.textVerbosity },
+  };
+  if (values.reasoningEffort || values.reasoningSummary) {
+    input.reasoning = {
+      ...(values.reasoningEffort ? { effort: values.reasoningEffort } : {}),
+      ...(values.reasoningSummary ? { summary: values.reasoningSummary } : {}),
+    };
+  }
+  return input;
+}
+
+export function buildAgentRequestPreview(values: AgentFormValues, baseUrl: string) {
+  const input = agentInputForPreview(values);
+  return {
+    curl: [
+      `curl --request POST ${previewEndpointArgument(baseUrl)} \\`,
+      `  --header "Authorization: Bearer ${previewTokenPlaceholder}" \\`,
+      '  --header "Content-Type: application/json" \\',
+      '  --header "OpenAI-Beta: agents=v1" \\',
+      "  --data @agent.json",
+    ].join("\n"),
+    json: JSON.stringify(input, null, 2),
+  };
+}
diff --git a/apps/web/src/features/environments/EnvironmentsView.test.tsx b/apps/web/src/features/environments/EnvironmentsView.test.tsx
new file mode 100644
index 0000000..09a7c50
--- /dev/null
+++ b/apps/web/src/features/environments/EnvironmentsView.test.tsx
@@ -0,0 +1,112 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import type { AgentSession } from "@agents-core-web/agents-client";
+
+import type { ScopedEnvironmentObservation } from "../sessions/environment/environment-state";
+import { EnvironmentsView, observedEnvironments } from "./EnvironmentsView";
+
+const selfHosted: AgentSession = {
+  id: "session-1",
+  object: "agent.session",
+  agent: {
+    id: "agent-1",
+    model: "provider/model",
+    name: "Builder",
+    instructions: null,
+    multi_agent: { enabled: false, max_concurrent_subagents: null },
+    reasoning: {},
+    service_tier: "auto",
+    text: { format: { type: "text" }, verbosity: "medium" },
+    tools: [],
+  },
+  environment: {
+    type: "self_hosted",
+    id: "environment-1",
+    remote_url: "https://executor.example/connect?private=hidden",
+    workspace_directory: "/workspace/project",
+    capability_directories: [],
+  },
+  status: "idle",
+  error: null,
+  metadata: {},
+  required_actions: [],
+  vault_ids: [],
+  usage: null,
+  created_at: 1,
+  last_active_at: 1,
+};
+
+const expiredObservation: ScopedEnvironmentObservation = {
+  sessionId: selfHosted.id,
+  streamEpoch: 1,
+  observation: {
+    source: "durable",
+    environmentId: "environment-1",
+    environmentType: "self_hosted",
+    status: "expired",
+    resource: {
+      id: "environment-1",
+      object: "agent.environment",
+      type: "self_hosted",
+      status: "expired",
+      files: [],
+      plugins: [],
+      skills: [],
+    },
+  },
+};
+
+describe("Environments overview", () => {
+  it("derives only self-hosted projections and keeps the matching observation", () => {
+    const none = { ...selfHosted, id: "session-none", environment: { type: "none" as const } };
+    const observed = observedEnvironments(
+      [none, selfHosted],
+      new Map([[selfHosted.id, expiredObservation]]),
+    );
+
+    expect(observed).toHaveLength(1);
+    expect(observed[0]?.environment.id).toBe("environment-1");
+    expect(observed[0]?.observation?.status).toBe("expired");
+  });
+
+  it("ignores malformed and future Environment projections instead of crashing", () => {
+    const malformed = {
+      ...selfHosted,
+      id: "session-malformed",
+      environment: null,
+    } as unknown as AgentSession;
+    const future = {
+      ...selfHosted,
+      id: "session-future",
+      environment: { type: "future_hosted", id: "environment-future" },
+    } as unknown as AgentSession;
+
+    expect(observedEnvironments([malformed, future], new Map())).toEqual([]);
+    expect(() => renderToStaticMarkup(
+      <EnvironmentsView
+        sessions={[malformed, future]}
+        observations={new Map()}
+        onOpenSession={() => undefined}
+      />,
+    )).not.toThrow();
+  });
+
+  it("renders explicit catalog, template, key, and readiness boundaries", () => {
+    const html = renderToStaticMarkup(
+      <EnvironmentsView
+        sessions={[selfHosted]}
+        observations={new Map([[selfHosted.id, expiredObservation]])}
+        onOpenSession={() => undefined}
+      />,
+    );
+
+    expect(html).toContain("Not an exhaustive Environment catalog");
+    expect(html).toContain("Environment templates");
+    expect(html).toContain("Environment keys");
+    expect(html).toContain("No secret is created, stored, or displayed here");
+    expect(html).toContain("Environment expired");
+    expect(html).toContain("does not prove executor, runtime, model, or provider readiness");
+    expect(html).not.toContain("private=hidden");
+  });
+});
diff --git a/apps/web/src/features/environments/EnvironmentsView.tsx b/apps/web/src/features/environments/EnvironmentsView.tsx
new file mode 100644
index 0000000..523e636
--- /dev/null
+++ b/apps/web/src/features/environments/EnvironmentsView.tsx
@@ -0,0 +1,171 @@
+import { AlertCircle, Eye, FileBox, KeyRound, Search } from "lucide-react";
+import { useState } from "react";
+
+import type {
+  AgentSession,
+  EnvironmentConnectionAction,
+  SelfHostedAgentEnvironment,
+} from "@agents-core-web/agents-client";
+
+import { EnvironmentPanel } from "../sessions/environment/EnvironmentPanel";
+import {
+  environmentIdsMatch,
+  type EnvironmentObservation,
+  type ScopedEnvironmentObservation,
+} from "../sessions/environment/environment-state";
+
+export interface ObservedEnvironment {
+  environment: SelfHostedAgentEnvironment;
+  observation: EnvironmentObservation | null;
+  session: AgentSession;
+}
+
+function isSelfHostedEnvironment(environment: unknown): environment is SelfHostedAgentEnvironment {
+  if (environment === null || typeof environment !== "object" || Array.isArray(environment)) return false;
+  const value = environment as Record<string, unknown>;
+  return value.type === "self_hosted" &&
+    typeof value.id === "string" &&
+    typeof value.remote_url === "string" &&
+    typeof value.workspace_directory === "string" &&
+    Array.isArray(value.capability_directories) &&
+    value.capability_directories.every((entry) => typeof entry === "string");
+}
+
+function connectionActions(session: AgentSession): EnvironmentConnectionAction[] {
+  const actions: unknown = session.required_actions;
+  if (!Array.isArray(actions)) return [];
+  return actions.filter((action): action is EnvironmentConnectionAction => (
+    action !== null &&
+    typeof action === "object" &&
+    (action as Record<string, unknown>).type === "environment_connection" &&
+    typeof (action as Record<string, unknown>).environment_id === "string"
+  ));
+}
+
+export function observedEnvironments(
+  sessions: AgentSession[],
+  observations: ReadonlyMap<string, ScopedEnvironmentObservation>,
+): ObservedEnvironment[] {
+  return sessions.flatMap((session) => {
+    const environment: unknown = session.environment;
+    if (!isSelfHostedEnvironment(environment)) return [];
+    const scoped = observations.get(session.id);
+    const observation = scoped?.sessionId === session.id &&
+      environmentIdsMatch(scoped.observation.environmentId, environment.id)
+      ? scoped.observation
+      : null;
+    return [{ environment, observation, session }];
+  });
+}
+
+export function EnvironmentsView({
+  observations,
+  onOpenSession,
+  sessions,
+}: {
+  observations: ReadonlyMap<string, ScopedEnvironmentObservation>;
+  onOpenSession: (sessionId: string) => void;
+  sessions: AgentSession[];
+}) {
+  const [query, setQuery] = useState("");
+  const allObserved = observedEnvironments(sessions, observations);
+  const normalizedQuery = query.trim().toLowerCase();
+  const visible = normalizedQuery ? allObserved.filter(({ environment, session }) => [
+    environment.id,
+    environment.workspace_directory,
+    environment.remote_url,
+    session.id,
+    session.agent.name,
+  ].some((value) => value?.toLowerCase().includes(normalizedQuery))) : allObserved;
+
+  return (
+    <section className="page-section environments-page">
+      <header className="page-header environments-header">
+        <div>
+          <h1>Environments <span>Observed</span></h1>
+          <p>Session-scoped self-hosted projections from the currently loaded Core data.</p>
+        </div>
+        <label className="search-control">
+          <Search size={14} strokeWidth={1.5} aria-hidden="true" />
+          <input
+            type="search"
+            value={query}
+            onChange={(event) => setQuery(event.target.value)}
+            placeholder="Search Environment, Session, or path…"
+            aria-label="Search observed Environments"
+          />
+        </label>
+      </header>
+
+      <div className="environments-scroll">
+        <section className="environment-catalog-boundary" role="note" aria-label="Environment catalog boundary">
+          <AlertCircle size={16} strokeWidth={1.5} aria-hidden="true" />
+          <div>
+            <strong>Not an exhaustive Environment catalog</strong>
+            <p>
+              Agent Core exposes retrieval by ID, not list. This view derives only from {sessions.length} currently loaded Session{sessions.length === 1 ? "" : "s"}; absent Environments remain unknown.
+            </p>
+          </div>
+        </section>
+
+        <section className="environment-unavailable-grid" aria-label="Unavailable Environment APIs">
+          <article>
+            <FileBox size={17} strokeWidth={1.5} aria-hidden="true" />
+            <div><strong>Environment templates</strong><span>Unavailable</span></div>
+            <p>The connected Core contract has no template create, list, retrieve, update, or delete API.</p>
+          </article>
+          <article>
+            <KeyRound size={17} strokeWidth={1.5} aria-hidden="true" />
+            <div><strong>Environment keys</strong><span>Operator-owned</span></div>
+            <p>Executor credentials are issued outside the browser. No secret is created, stored, or displayed here.</p>
+          </article>
+        </section>
+
+        <section className="observed-environments" aria-labelledby="observed-environments-title">
+          <header>
+            <div>
+              <h2 id="observed-environments-title">Observed self-hosted Environments</h2>
+              <p>Durable Session projection plus the latest matching Environment observation already read by this Web.</p>
+            </div>
+            <span>{visible.length}{normalizedQuery ? ` of ${allObserved.length}` : ""}</span>
+          </header>
+
+          {visible.length ? (
+            <div className="observed-environment-list">
+              {visible.map(({ environment, observation, session }) => (
+                <article className="observed-environment" key={`${session.id}:${environment.id}`}>
+                  <header>
+                    <div>
+                      <strong>{session.agent.name || "Untitled Agent"}</strong>
+                      <span>Session <code>{session.id}</code></span>
+                    </div>
+                    <button className="button outline" type="button" onClick={() => onOpenSession(session.id)}>
+                      <Eye size={13} strokeWidth={1.5} aria-hidden="true" />
+                      Open Session
+                    </button>
+                  </header>
+                  <EnvironmentPanel
+                    environment={environment}
+                    observation={observation}
+                    connectionActions={connectionActions(session)}
+                  />
+                </article>
+              ))}
+            </div>
+          ) : (
+            <div className="environment-overview-empty">
+              <Eye size={22} strokeWidth={1.5} aria-hidden="true" />
+              <h3>{allObserved.length ? "No matching observed Environments" : "No self-hosted Environment is currently observed"}</h3>
+              <p>
+                {allObserved.length
+                  ? "Try another Environment ID, Session ID, or Workspace path."
+                  : "Loaded environment:none Sessions do not appear here. This is not proof that Core has no other Environments."}
+              </p>
+              {allObserved.length ? <button className="button outline" type="button" onClick={() => setQuery("")}>Clear search</button> : null}
+            </div>
+          )}
+        </section>
+      </div>
+    </section>
+  );
+}
diff --git a/apps/web/src/features/sessions/SessionsView.tsx b/apps/web/src/features/sessions/SessionsView.tsx
index 5e47f6b..872246a 100644
--- a/apps/web/src/features/sessions/SessionsView.tsx
+++ b/apps/web/src/features/sessions/SessionsView.tsx
@@ -52,6 +52,8 @@ interface SessionsViewProps {
   busy: boolean;
   coreError: string | null;
   coreState: CoreConnectionState;
+  createRequest?: number;
+  onCreateRequestConsumed?: (request: number) => void;
   detailError: string | null;
   detailState: SessionDetailState;
   turnError?: string | null;
@@ -275,6 +277,8 @@ export function SessionsView({
   busy,
   coreError,
   coreState,
+  createRequest = 0,
+  onCreateRequestConsumed,
   detailError,
   detailState,
   turnError = null,
@@ -304,6 +308,7 @@ export function SessionsView({
   const sendingRef = useRef(false);
   const pageRef = useRef<HTMLElement>(null);
   const newSessionActionRef = useRef<HTMLButtonElement>(null);
+  const lastCreateRequestRef = useRef(0);
   const conversationActionRef = useRef<HTMLButtonElement>(null);
   const restoreFocusAfterDeleteRef = useRef(false);
   const draftsBySessionRef = useRef(new Map<string, string>());
@@ -319,6 +324,13 @@ export function SessionsView({
     if (!agentId && agents[0]) setAgentId(agents[0].id);
   }, [agentId, agents]);
 
+  useEffect(() => {
+    if (!createRequest || createRequest === lastCreateRequestRef.current) return;
+    lastCreateRequestRef.current = createRequest;
+    setNewSessionOpen(true);
+    onCreateRequestConsumed?.(createRequest);
+  }, [createRequest, onCreateRequestConsumed]);
+
   useEffect(() => {
     if (actionSession && !sessions.some((session) => session.id === actionSession.id)) {
       setActionSession(null);
diff --git a/apps/web/src/style.css b/apps/web/src/style.css
index aa98be5..b450314 100644
--- a/apps/web/src/style.css
+++ b/apps/web/src/style.css
@@ -3745,6 +3745,772 @@ button.trace-step-row:hover {
   color: var(--fg-muted);
 }
 
+/* Product navigation and global creation keep OpenAI's clear information
+   architecture inside Parsar's existing Issue Ledger visual system. */
+
+.product-header {
+  position: relative;
+  z-index: 12;
+  display: flex;
+  min-height: 54px;
+  flex: 0 0 54px;
+  align-items: flex-end;
+  padding: 0 20px;
+  gap: 16px;
+  background: var(--surface);
+  border-bottom: 1px solid var(--line);
+}
+
+.product-navigation {
+  display: flex;
+  min-width: 0;
+  align-self: stretch;
+  align-items: flex-end;
+  gap: 22px;
+  overflow-x: auto;
+}
+
+.product-navigation button {
+  position: relative;
+  height: 38px;
+  flex: 0 0 auto;
+  padding: 0 1px;
+  color: var(--fg-muted);
+  font-size: 14px;
+  background: transparent;
+  border: 0;
+}
+
+.product-navigation button:hover,
+.product-navigation button.active {
+  color: var(--fg);
+}
+
+.product-navigation button.active::after {
+  position: absolute;
+  right: 0;
+  bottom: -1px;
+  left: 0;
+  height: 2px;
+  content: "";
+  background: var(--fg);
+  border-radius: 2px 2px 0 0;
+}
+
+.product-navigation button:focus-visible,
+.create-menu [role="menuitem"]:focus-visible {
+  outline: 2px solid color-mix(in srgb, var(--accent) 45%, transparent);
+  outline-offset: 2px;
+}
+
+.create-menu {
+  position: relative;
+  margin: 0 0 9px auto;
+}
+
+.create-menu-trigger {
+  height: 34px;
+  padding: 0 11px;
+  gap: 7px;
+}
+
+.create-menu-panel {
+  position: absolute;
+  top: calc(100% + 7px);
+  right: 0;
+  z-index: 30;
+  display: grid;
+  width: 350px;
+  padding: 7px;
+  gap: 2px;
+  color: var(--fg);
+  background: var(--surface);
+  border: 1px solid var(--line-strong);
+  border-radius: 10px;
+  box-shadow: var(--shadow-floating);
+}
+
+.create-menu-panel > button,
+.create-menu-unavailable {
+  display: grid;
+  grid-template-columns: 18px minmax(0, 1fr);
+  min-height: 54px;
+  align-items: flex-start;
+  padding: 9px 10px;
+  gap: 10px;
+  text-align: left;
+  background: transparent;
+  border: 0;
+  border-radius: 7px;
+}
+
+.create-menu-panel > button:not(:disabled):hover,
+.create-menu-panel > button:not(:disabled):focus-visible {
+  background: var(--hover);
+}
+
+.create-menu-panel > button:disabled,
+.create-menu-unavailable {
+  color: var(--fg-muted);
+  opacity: 0.72;
+}
+
+.create-menu-panel svg {
+  margin-top: 2px;
+}
+
+.create-menu-panel span {
+  display: flex;
+  min-width: 0;
+  flex-direction: column;
+}
+
+.create-menu-panel strong {
+  font-size: 14px;
+  font-weight: 500;
+  line-height: 19px;
+}
+
+.create-menu-panel small {
+  color: var(--fg-muted);
+  font-size: 12px;
+  font-weight: 400;
+  line-height: 17px;
+}
+
+/* Dedicated Agent setup. */
+
+.agent-setup-page {
+  display: flex;
+  min-height: 0;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.agent-setup-header {
+  display: flex;
+  min-height: 82px;
+  flex: 0 0 auto;
+  flex-direction: column;
+  justify-content: space-between;
+  padding: 13px 24px 0;
+  border-bottom: 1px solid var(--line);
+}
+
+.agent-setup-breadcrumb {
+  display: flex;
+  min-width: 0;
+  align-items: center;
+  gap: 7px;
+}
+
+.agent-setup-breadcrumb button {
+  padding: 0;
+  color: var(--fg-muted);
+  background: transparent;
+  border: 0;
+}
+
+.agent-setup-breadcrumb button:hover {
+  color: var(--fg);
+}
+
+.agent-setup-breadcrumb h1 {
+  min-width: 0;
+  margin: 0;
+  overflow: hidden;
+  font-size: 20px;
+  font-weight: 600;
+  line-height: 26px;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.agent-setup-tabs {
+  display: flex;
+  gap: 22px;
+}
+
+.agent-setup-tabs button {
+  position: relative;
+  min-height: 32px;
+  padding: 0;
+  color: var(--fg-muted);
+  font-size: 13px;
+  background: transparent;
+  border: 0;
+}
+
+.agent-setup-tabs button[aria-selected="true"] {
+  color: var(--fg);
+  font-weight: 500;
+}
+
+.agent-setup-tabs button[aria-selected="true"]::after {
+  position: absolute;
+  right: 0;
+  bottom: -1px;
+  left: 0;
+  height: 2px;
+  content: "";
+  background: var(--fg);
+}
+
+.agent-setup-layout {
+  display: grid;
+  min-width: 0;
+  min-height: 0;
+  flex: 1;
+  grid-template-columns: minmax(360px, 0.9fr) minmax(420px, 1.1fr);
+  overflow: hidden;
+}
+
+.agent-setup-editor,
+.agent-setup-aside {
+  min-width: 0;
+  overflow-y: auto;
+}
+
+.agent-setup-editor {
+  padding: 22px 24px 32px;
+  border-right: 1px solid var(--line);
+}
+
+.agent-setup-aside {
+  display: grid;
+  align-content: start;
+  padding: 22px;
+  gap: 18px;
+  background: var(--surface-subtle);
+}
+
+.agent-form-fields {
+  display: flex;
+  min-width: 0;
+  margin: 0;
+  padding: 0;
+  flex-direction: column;
+  gap: 14px;
+  border: 0;
+}
+
+.agent-form-section {
+  margin: 2px 0;
+  padding: 14px;
+  background: var(--surface-subtle);
+  border: 1px solid var(--line);
+  border-radius: 8px;
+}
+
+.agent-form-section-heading {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  margin-bottom: 10px;
+  gap: 10px;
+}
+
+.agent-form-section-heading h3 {
+  margin: 0;
+  font-size: 13px;
+  font-weight: 500;
+}
+
+.agent-form-section-heading span,
+.agent-form-capability-note {
+  color: var(--fg-muted);
+  font-size: 11px;
+  line-height: 16px;
+}
+
+.agent-form-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 10px;
+}
+
+.agent-form-capability-note {
+  margin: 10px 0 0;
+}
+
+.agent-setup-actions {
+  display: flex;
+  align-items: center;
+  margin-top: 18px;
+  padding-top: 14px;
+  gap: 8px;
+  border-top: 1px solid var(--line);
+}
+
+.agent-start-session {
+  margin-left: auto;
+  gap: 6px;
+}
+
+.agent-created-notice {
+  margin-bottom: 14px;
+}
+
+.agent-created-notice code {
+  font-family: var(--font-mono);
+  font-size: 11px;
+}
+
+.agent-request-preview,
+.agent-setup-guide {
+  min-width: 0;
+  padding: 16px;
+  background: var(--surface);
+  border: 1px solid var(--line);
+  border-radius: 9px;
+  box-shadow: var(--shadow-control);
+}
+
+.agent-request-preview > header {
+  display: flex;
+  align-items: flex-start;
+  gap: 9px;
+}
+
+.agent-request-preview h2,
+.agent-setup-guide h2 {
+  margin: 0;
+  font-size: 14px;
+  font-weight: 600;
+  line-height: 20px;
+}
+
+.agent-request-preview header p {
+  margin: 2px 0 0;
+  color: var(--fg-muted);
+  font-size: 11px;
+  line-height: 16px;
+}
+
+.agent-preview-block {
+  margin-top: 12px;
+  overflow: hidden;
+  background: var(--surface-inverse);
+  border-radius: 7px;
+}
+
+.agent-preview-block > span {
+  display: block;
+  padding: 6px 10px;
+  color: color-mix(in srgb, var(--surface) 65%, transparent);
+  font-family: var(--font-mono);
+  font-size: 10px;
+  border-bottom: 1px solid color-mix(in srgb, var(--surface) 15%, transparent);
+}
+
+.agent-preview-block pre {
+  max-height: 250px;
+  margin: 0;
+  padding: 11px;
+  overflow: auto;
+  color: var(--surface);
+  font-family: var(--font-mono);
+  font-size: 11px;
+  line-height: 17px;
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+}
+
+.agent-setup-guide ol {
+  display: grid;
+  margin: 14px 0 0;
+  padding: 0;
+  gap: 0;
+  list-style: none;
+}
+
+.agent-setup-guide li {
+  position: relative;
+  display: grid;
+  grid-template-columns: 18px minmax(0, 1fr);
+  padding: 0 0 17px;
+  gap: 9px;
+}
+
+.agent-setup-guide li:not(:last-child)::after {
+  position: absolute;
+  top: 15px;
+  bottom: 2px;
+  left: 6px;
+  width: 1px;
+  content: "";
+  background: var(--line-strong);
+}
+
+.agent-setup-guide li > svg {
+  margin-top: 2px;
+  color: var(--fg-muted);
+}
+
+.agent-setup-guide li.complete > svg {
+  color: var(--success);
+}
+
+.agent-setup-guide li > div {
+  display: flex;
+  min-width: 0;
+  flex-direction: column;
+}
+
+.agent-setup-guide li strong {
+  font-size: 13px;
+  font-weight: 500;
+}
+
+.agent-setup-guide li span {
+  color: var(--fg-muted);
+  font-size: 12px;
+  line-height: 17px;
+}
+
+/* Session-derived Environments overview. */
+
+.environments-page {
+  display: flex;
+  min-height: 0;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.environments-header > div:first-child {
+  min-width: 0;
+}
+
+.environments-header h1 span {
+  color: var(--fg-muted);
+  font-size: 12px;
+  font-weight: 400;
+}
+
+.environments-header p {
+  margin: 2px 0 0;
+  overflow: hidden;
+  color: var(--fg-muted);
+  font-size: 11px;
+  line-height: 15px;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.environments-header .search-control {
+  width: min(340px, 40vw);
+  margin-left: auto;
+}
+
+.environments-scroll {
+  min-height: 0;
+  padding: 22px 24px 48px;
+  overflow-y: auto;
+}
+
+.environment-catalog-boundary {
+  display: flex;
+  max-width: 960px;
+  padding: 12px 14px;
+  gap: 10px;
+  color: var(--fg);
+  background: color-mix(in srgb, var(--warning) 7%, var(--surface));
+  border: 1px solid color-mix(in srgb, var(--warning) 25%, var(--line));
+  border-radius: 8px;
+}
+
+.environment-catalog-boundary > svg {
+  flex: 0 0 auto;
+  margin-top: 1px;
+  color: var(--warning);
+}
+
+.environment-catalog-boundary strong {
+  font-size: 13px;
+  font-weight: 500;
+}
+
+.environment-catalog-boundary p {
+  margin: 2px 0 0;
+  color: var(--fg-muted);
+  font-size: 12px;
+  line-height: 17px;
+}
+
+.environment-unavailable-grid {
+  display: grid;
+  max-width: 960px;
+  margin-top: 14px;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 10px;
+}
+
+.environment-unavailable-grid article {
+  display: grid;
+  grid-template-columns: 20px minmax(0, 1fr);
+  padding: 13px;
+  gap: 4px 9px;
+  background: var(--surface-subtle);
+  border: 1px solid var(--line);
+  border-radius: 8px;
+}
+
+.environment-unavailable-grid article > svg {
+  margin-top: 1px;
+  color: var(--fg-muted);
+}
+
+.environment-unavailable-grid article > div {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  gap: 8px;
+}
+
+.environment-unavailable-grid strong {
+  font-size: 13px;
+  font-weight: 500;
+}
+
+.environment-unavailable-grid span {
+  color: var(--fg-muted);
+  font-size: 10px;
+  text-transform: uppercase;
+}
+
+.environment-unavailable-grid p {
+  grid-column: 2;
+  margin: 0;
+  color: var(--fg-muted);
+  font-size: 11px;
+  line-height: 16px;
+}
+
+.observed-environments {
+  max-width: 960px;
+  margin-top: 26px;
+}
+
+.observed-environments > header {
+  display: flex;
+  align-items: flex-end;
+  justify-content: space-between;
+  margin-bottom: 9px;
+  gap: 12px;
+}
+
+.observed-environments h2 {
+  margin: 0;
+  font-size: 15px;
+  font-weight: 600;
+}
+
+.observed-environments header p {
+  margin: 2px 0 0;
+  color: var(--fg-muted);
+  font-size: 11px;
+  line-height: 16px;
+}
+
+.observed-environments > header > span {
+  color: var(--fg-muted);
+  font-family: var(--font-mono);
+  font-size: 12px;
+}
+
+.observed-environment-list {
+  display: grid;
+  gap: 10px;
+}
+
+.observed-environment {
+  overflow: hidden;
+  border: 1px solid var(--line);
+  border-radius: 8px;
+}
+
+.observed-environment > header {
+  display: flex;
+  min-height: 46px;
+  align-items: center;
+  justify-content: space-between;
+  padding: 7px 10px 7px 13px;
+  gap: 12px;
+  background: var(--surface-subtle);
+  border-bottom: 1px solid var(--line);
+}
+
+.observed-environment > header > div {
+  display: flex;
+  min-width: 0;
+  flex-direction: column;
+}
+
+.observed-environment > header strong {
+  font-size: 13px;
+  font-weight: 500;
+}
+
+.observed-environment > header span {
+  overflow: hidden;
+  color: var(--fg-muted);
+  font-size: 11px;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.observed-environment > header code {
+  font-family: var(--font-mono);
+  font-size: 10px;
+}
+
+.observed-environment > .environment-panel {
+  margin: 0;
+  border: 0;
+  border-radius: 0;
+}
+
+.environment-overview-empty {
+  display: flex;
+  min-height: 180px;
+  align-items: center;
+  justify-content: center;
+  padding: 24px;
+  flex-direction: column;
+  color: var(--fg-muted);
+  text-align: center;
+  background: var(--surface-subtle);
+  border: 1px dashed var(--line-strong);
+  border-radius: 8px;
+}
+
+.environment-overview-empty h3 {
+  margin: 9px 0 2px;
+  color: var(--fg);
+  font-size: 14px;
+  font-weight: 500;
+}
+
+.environment-overview-empty p {
+  max-width: 560px;
+  margin: 0 0 12px;
+  font-size: 12px;
+}
+
+@media (max-width: 1000px) {
+  .agent-setup-layout {
+    grid-template-columns: minmax(340px, 1fr) minmax(360px, 1fr);
+  }
+
+  .agent-form-grid {
+    grid-template-columns: 1fr;
+  }
+}
+
+@media (max-width: 640px) {
+  .product-header {
+    min-height: 48px;
+    flex-basis: 48px;
+    padding: 0 10px;
+    gap: 8px;
+  }
+
+  .product-navigation {
+    gap: 14px;
+  }
+
+  .product-navigation button {
+    height: 34px;
+    font-size: 12px;
+  }
+
+  .create-menu {
+    margin-bottom: 7px;
+  }
+
+  .create-menu-trigger {
+    width: 34px;
+    padding: 0;
+    gap: 0;
+    font-size: 0;
+  }
+
+  .create-menu-trigger svg:last-child {
+    display: none;
+  }
+
+  .create-menu-panel {
+    position: fixed;
+    top: 52px;
+    right: 8px;
+    width: min(350px, calc(100vw - 68px));
+  }
+
+  .agent-setup-header {
+    min-height: 76px;
+    padding: 10px 12px 0;
+  }
+
+  .agent-setup-layout {
+    display: block;
+    overflow-y: auto;
+  }
+
+  .agent-setup-editor,
+  .agent-setup-aside {
+    overflow: visible;
+  }
+
+  .agent-setup-editor {
+    padding: 16px 12px 22px;
+    border-right: 0;
+  }
+
+  .agent-setup-aside {
+    padding: 16px 12px 32px;
+    border-top: 1px solid var(--line);
+  }
+
+  .agent-form-grid,
+  .environment-unavailable-grid {
+    grid-template-columns: 1fr;
+  }
+
+  .agent-setup-actions {
+    flex-wrap: wrap;
+  }
+
+  .agent-start-session {
+    width: 100%;
+    margin-left: 0;
+  }
+
+  .environments-header {
+    min-height: auto;
+    flex: 0 0 auto;
+    flex-wrap: wrap;
+    padding: 10px 12px;
+  }
+
+  .environments-header .search-control {
+    width: 100%;
+    margin-left: 0;
+  }
+
+  .environments-scroll {
+    padding: 14px 12px 32px;
+  }
+
+  .observed-environment > header {
+    align-items: flex-start;
+    flex-direction: column;
+  }
+
+  .observed-environment > header .button {
+    width: 100%;
+  }
+}
+
 @keyframes overlay-in {
   from { opacity: 0; }
   to { opacity: 1; }
diff --git a/docs/protocol-coverage.md b/docs/protocol-coverage.md
index 698d000..305841e 100644
--- a/docs/protocol-coverage.md
+++ b/docs/protocol-coverage.md
@@ -7,6 +7,11 @@ OpenAI-hosted service compatibility.
 
 - Parsar Core:
   [`0438880a`](https://github.com/MiniMax-AI-Dev/parsar/commit/0438880ab21aa16d05cb91a4c7f91cc0abc12358)
+- The product-navigation and Environment-unavailable boundaries were re-audited
+  against Parsar [`c15d42a2`](https://github.com/MiniMax-AI-Dev/parsar/commit/c15d42a270c0667bcaa83a6b9d01a9892ebf7edd).
+  That revision still exposes only Environment retrieve plus Session-bound
+  `self_hosted` creation; it adds no public Environment list, template, file, or
+  browser-facing key management route.
 - Upstream resource source: `openai-python` 3.13.0 beta Agents resources at
   [`d7c41efe`](https://github.com/openai/openai-python/tree/d7c41efee1b0802b79f3f88a678ef2052b06e9ce/src/openai/resources/beta/agents)
 - Required beta header: `OpenAI-Beta: agents=v1`
@@ -27,7 +32,7 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 
 | Resource / behavior | TypeScript client | Initial UI | Notes |
 | --- | --- | --- | --- |
-| Saved Agents create/list | Yes | Yes | Model, name, instructions; many saved Agents per project |
+| Saved Agents create/list | Yes | Yes | Dedicated setup page covers model, name, instructions, metadata, read-only text-format projection, reasoning effort/summary, text verbosity, and service tier; saved settings do not prove runtime support |
 | Saved Agents retrieve/update/delete | Yes | Yes | Agent details support viewing, editing, and deleting saved Agents |
 | Sessions create/list/retrieve | Yes | Yes | UI creates idle `environment:none` Sessions; client types also cover the pinned `self_hosted` request and safe response projection |
 | Sessions update/delete | Yes | Yes | Title/string metadata editing and one-Session confirmed deletion; no bulk or Workspace deletion |
@@ -44,6 +49,9 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 | Environment connection action | Yes | Render-only | `environment_connection` is distinct from a function call; Web shows an operator-owned, non-actionable state and sends no result |
 | Environment lifecycle events | Yes | Read-only | UI projects pinned pending, ready, connected, disconnected, and failed live snapshots; unknown/malformed status events clear prior live claims and render as unavailable |
 | Environment retrieve | Yes | Yes, read-only | For a valid `self_hosted` Session Environment ID, reads the exact public resource fields and durable status; no create/list/update/delete support |
+| Environment overview | Session-derived only | Yes, read-only | Shows only `self_hosted` projections in currently loaded Sessions and their already-observed matching status; explicitly not a Core Environment catalog |
+| Environment templates | No | Explicitly unavailable | The navigation/Create surface does not simulate template reads or writes |
+| Environment keys | No public browser API | Explicitly unavailable | Operator-issued executor credentials never enter browser state or request previews |
 | Vaults | Later | No | Credentials must never be stored in browser metadata |
 | Protocol Subagents / enabled multi-agent | Later | No | Distinct from storing multiple Agent configurations |
 | Usage/observability | Response types | Yes, scoped | Session aggregate and per-Turn token Usage are labelled separately; unavailable measurements remain unknown, not zero |
@@ -51,6 +59,17 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 ## Runtime boundary
 
 - The Web currently creates only `environment: {"type":"none"}` Sessions.
+- Product navigation and the global Create menu do not widen the protocol. Agent
+  and idle Session creation call the existing client methods. Environment template
+  and Environment key entries are non-actionable unavailable states.
+- The Agent setup request preview is derived entirely from editable Agent fields and
+  the sanitized Core base URL. Its authorization header always contains the literal
+  `${AGENTS_CORE_API_KEY}` placeholder; it never reads or renders the connection's
+  server-managed or current-tab bearer.
+- The Environments overview filters the currently loaded Session collection to exact
+  `self_hosted` projections. A matching durable/live observation may annotate that
+  row, but an absent row or observation remains unknown. The view does not derive a
+  list from database state, Environment IDs, executor registrations, or operator keys.
 - Parsar Core at the pinned revision has a narrow `self_hosted` profile for empty
   Session creation followed by constrained idle text input. The Web does not create
   that profile, but it safely renders selected Sessions that already carry one. This

From 39e0a31555bfa44fb743524a0641da3099bf0fde Mon Sep 17 00:00:00 2001
From: sam2tom <sam2tom@users.noreply.github.com>
Date: Wed, 16 Sep 2026 17:08:22 +0800
Subject: [PATCH 2/3] fix(web): finish Core-backed agent setup alignment

---
 apps/web/e2e/agents-lifecycle.spec.ts         | 154 +++++++++++++++++-
 apps/web/e2e/fixture-core.mjs                 | 117 ++++++++++++-
 apps/web/src/App.tsx                          |  19 ++-
 apps/web/src/components/CreateMenu.tsx        |   2 +-
 .../src/components/ProductNavigation.test.tsx |   2 +
 apps/web/src/components/ProductNavigation.tsx |  40 +++--
 apps/web/src/features/agents/AgentForm.tsx    |  55 +++++--
 .../features/agents/AgentSetupView.test.tsx   |   4 +-
 .../src/features/agents/AgentSetupView.tsx    |  12 +-
 .../src/features/agents/AgentsView.test.tsx   |  30 +++-
 apps/web/src/features/agents/AgentsView.tsx   |  53 ++++--
 .../src/features/agents/agent-form.test.ts    |  46 +++++-
 apps/web/src/features/agents/agent-form.ts    |  39 ++++-
 .../src/features/agents/agent-preview.test.ts |  16 +-
 .../features/agents/session-admission.test.ts | 130 +++++++++++++++
 .../src/features/agents/session-admission.ts  | 134 +++++++++++++++
 .../src/features/sessions/SessionsView.tsx    |  65 ++++++--
 apps/web/src/style.css                        |  60 ++-----
 docs/protocol-coverage.md                     |  24 ++-
 19 files changed, 875 insertions(+), 127 deletions(-)
 create mode 100644 apps/web/src/features/agents/session-admission.test.ts
 create mode 100644 apps/web/src/features/agents/session-admission.ts

diff --git a/apps/web/e2e/agents-lifecycle.spec.ts b/apps/web/e2e/agents-lifecycle.spec.ts
index 43316db..a157cc0 100644
--- a/apps/web/e2e/agents-lifecycle.spec.ts
+++ b/apps/web/e2e/agents-lifecycle.spec.ts
@@ -135,7 +135,7 @@ test("retrieves latest details and reuses a validated create/edit form", async (
   await expect(dialog).not.toContainText("stale list");
   await expect(dialog).toContainText("agent_a");
   await expect(dialog).toContainText("Advanced configuration · read only");
-  await expect(dialog).toContainText("does not prove the current executor");
+  await expect(dialog).toContainText("known Core Session profile cannot start it");
   await expect(dialog.locator("input, textarea, select")).toHaveCount(0);
   await attachScreenshot(page, testInfo, "desktop-light-agent-details");
 
@@ -151,6 +151,14 @@ test("retrieves latest details and reuses a validated create/edit form", async (
   let requests = await fixtureRequests(request);
   expect(requests.filter((entry) => entry.method === "POST" && entry.path === "/v1/agents/agent_a")).toHaveLength(0);
 
+  await page.getByLabel("Metadata").fill(JSON.stringify(Object.fromEntries(
+    Array.from({ length: 17 }, (_, index) => [`key-${index}`, "value"]),
+  )));
+  await page.getByRole("button", { name: "Save changes" }).click();
+  await expect(page.getByText("Agent metadata supports at most 16 pairs.")).toBeVisible();
+  requests = await fixtureRequests(request);
+  expect(requests.filter((entry) => entry.method === "POST" && entry.path === "/v1/agents/agent_a")).toHaveLength(0);
+
   await name.fill("");
   await page.getByLabel("Instructions").fill("");
   await page.getByLabel("Metadata").fill('{"team":"acceptance"}');
@@ -173,6 +181,11 @@ test("retrieves latest details and reuses a validated create/edit form", async (
 
 test("supports global Create keyboard navigation and consumes setup requests once", async ({ page, request }) => {
   await openAgents(page, request);
+  const sidebar = page.locator(".app-sidebar");
+  const productNavigation = sidebar.getByRole("navigation", { name: "Agents product" });
+  await expect(productNavigation).toBeVisible();
+  await expect(productNavigation.getByRole("button", { name: "Agents", exact: true })).toHaveAttribute("aria-current", "page");
+  await expect(page.locator(".product-header").getByRole("navigation", { name: "Agents product" })).toHaveCount(0);
   const createMenu = page.getByRole("button", { name: "Create", exact: true });
   await createMenu.focus();
   await page.keyboard.press("Enter");
@@ -207,8 +220,18 @@ test("supports global Create keyboard navigation and consumes setup requests onc
 
   await createMenu.click();
   await startSessionItem.click();
-  await expect(page.getByRole("dialog", { name: "Start an idle Session" })).toBeVisible();
-  await page.getByRole("dialog", { name: "Start an idle Session" }).getByRole("button", { name: "Cancel" }).click();
+  const sessionDialog = page.getByRole("dialog", { name: "Start an idle Session" });
+  await expect(sessionDialog).toBeVisible();
+  await expect(sessionDialog.getByLabel("Saved Agent")).toHaveValue("agent_b");
+  await expect(sessionDialog.locator('option[value="agent_a"]')).toHaveAttribute("disabled", "");
+  await expect(sessionDialog.locator('option[value="agent_tool_only"]')).toHaveAttribute("disabled", "");
+  const sessionPostsBeforeCancel = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  )).length;
+  await sessionDialog.getByRole("button", { name: "Cancel" }).click();
+  expect((await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ))).toHaveLength(sessionPostsBeforeCancel);
   await expect(createMenu).toBeFocused();
   await page.getByRole("button", { name: "Agents", exact: true }).click();
   await page.getByRole("button", { name: "Sessions", exact: true }).click();
@@ -247,7 +270,132 @@ test("supports global Create keyboard navigation and consumes setup requests onc
     name: null,
     instructions: null,
     metadata: { owner: "local-test" },
+    service_tier: "auto",
+    text: { format: { type: "text" }, verbosity: "medium" },
+  });
+  expect(creates[0]?.body).not.toHaveProperty("reasoning");
+});
+
+test("continues from a default Agent definition into an admitted idle Session", async ({ page, request }) => {
+  await openAgents(page, request);
+  await page.getByRole("button", { name: "New Agent" }).click();
+  await page.getByLabel("Name").fill("Session-safe Agent");
+  await page.getByRole("button", { name: "Save Agent definition" }).click();
+  await expect(page.getByRole("status")).toContainText("Agent definition saved as");
+
+  const requestsAfterSave = await fixtureRequests(request);
+  const create = requestsAfterSave.find((entry) => entry.method === "POST" && entry.path === "/v1/agents");
+  expect(create?.body).toMatchObject({
+    name: "Session-safe Agent",
+    service_tier: "auto",
+    text: { format: { type: "text" }, verbosity: "medium" },
   });
+  expect(create?.body).not.toHaveProperty("reasoning");
+
+  await expect(page.getByRole("button", { name: "Start Session" })).toBeEnabled();
+  await page.getByRole("button", { name: "Start Session" }).click();
+  await expect(page.getByRole("button", { name: "Sessions", exact: true })).toHaveAttribute("aria-current", "page");
+
+  const sessionCreates = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ));
+  expect(sessionCreates).toHaveLength(1);
+  expect(sessionCreates[0]?.body).toMatchObject({
+    agent_id: expect.stringMatching(/^agent_created_/),
+    environment: { type: "none" },
+    stream: false,
+  });
+});
+
+test("rechecks the saved response before offering the setup-page Session continuation", async ({ page, request }) => {
+  await openAgents(page, request);
+  await controlFixture(request, { createAgentResponseVariant: "reasoning" });
+  await page.getByRole("button", { name: "New Agent" }).click();
+  await page.getByLabel("Name").fill("Core-adjusted Agent");
+  await page.getByRole("button", { name: "Save Agent definition" }).click();
+
+  await expect(page.getByRole("status")).toContainText("Agent definition saved as");
+  await expect(page.locator("#created-agent-session-blocker")).toContainText("Start Session is unavailable");
+  const startSession = page.getByRole("button", { name: "Start Session" });
+  await expect(startSession).toBeDisabled();
+
+  // Bypass the setup view's disabled control to prove App's final admission
+  // guard independently blocks the write if a caller reaches it anyway.
+  await startSession.evaluate((button) => {
+    const propsKey = Object.getOwnPropertyNames(button).find((key) => key.startsWith("__reactProps$"));
+    if (!propsKey) throw new Error("React event props were not found on the Start Session button.");
+    const props = (button as unknown as Record<string, { onClick?: () => void }>)[propsKey];
+    if (!props?.onClick) throw new Error("Start Session does not have an onClick handler.");
+    props.onClick();
+  });
+  await expect(page.getByText(/Session was not created\./)).toBeVisible();
+  expect((await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ))).toHaveLength(0);
+});
+
+test("starts only Agents that pass known Session admission", async ({ page, request }) => {
+  await openAgents(page, request);
+
+  const blockedStart = page.getByRole("button", { name: /Start a Session with Lifecycle Agent/ });
+  await expect(blockedStart).toHaveAttribute("aria-disabled", "true");
+  await blockedStart.focus();
+  await expect(blockedStart.locator("xpath=..").getByRole("tooltip")).toBeVisible();
+  const blockedSessionCount = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  )).length;
+  await page.keyboard.press("Enter");
+  expect((await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ))).toHaveLength(blockedSessionCount);
+
+  const toolOnlyStart = page.getByRole("button", { name: "Start a Session with Saved-only Tool Agent" });
+  await expect(toolOnlyStart).toHaveAttribute("aria-disabled", "true");
+  await toolOnlyStart.focus();
+  await expect(toolOnlyStart.locator("xpath=..").getByRole("tooltip")).toContainText("tool_search is saved-only");
+  await page.keyboard.press("Enter");
+  expect((await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ))).toHaveLength(blockedSessionCount);
+  await expect(page.getByRole("button", { name: "Start a Session with Second Agent" })).toBeEnabled();
+
+  const before = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  )).length;
+  await page.getByRole("button", { name: "Start a Session with Second Agent" }).click();
+  await expect(page.getByRole("button", { name: "Sessions", exact: true })).toHaveAttribute("aria-current", "page");
+
+  const sessionCreates = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ));
+  expect(sessionCreates).toHaveLength(before + 1);
+  expect(sessionCreates.at(-1)?.body).toMatchObject({
+    agent_id: "agent_b",
+    environment: { type: "none" },
+    stream: false,
+  });
+});
+
+test("keeps the New Session reason keyboard-accessible when every loaded Agent is incompatible", async ({ page, request }) => {
+  await openAgents(page, request);
+  const deleted = await request.delete(`${fixtureBaseUrl}/v1/agents/agent_b`);
+  expect(deleted.ok()).toBe(true);
+  await page.getByRole("button", { name: "Refresh Agents" }).click();
+  await expect(page.getByRole("button", { name: "Open details for Second Agent" })).toHaveCount(0);
+
+  await page.getByRole("button", { name: "Sessions", exact: true }).click();
+  const newSession = page.getByRole("button", { name: "New Session" });
+  await expect(newSession).toHaveAttribute("aria-disabled", "true");
+  await newSession.focus();
+  await expect(newSession.locator("xpath=..").getByRole("tooltip")).toContainText("No loaded Agent matches");
+  const before = (await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  )).length;
+  await page.keyboard.press("Enter");
+  await expect(page.getByRole("dialog", { name: "Start an idle Session" })).toHaveCount(0);
+  expect((await fixtureRequests(request)).filter((entry) => (
+    entry.method === "POST" && entry.path === "/v1/agents/sessions"
+  ))).toHaveLength(before);
 });
 
 test("keeps failures visible, rejects stale async continuations, and never retries writes", async ({ page, request }) => {
diff --git a/apps/web/e2e/fixture-core.mjs b/apps/web/e2e/fixture-core.mjs
index 0d72f98..e6dfee1 100644
--- a/apps/web/e2e/fixture-core.mjs
+++ b/apps/web/e2e/fixture-core.mjs
@@ -63,6 +63,97 @@ function savedAgent(id, name, model, updatedAt) {
   };
 }
 
+function isRecord(value) {
+  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
+}
+
+function hasOnlyKeys(value, allowed) {
+  return Object.keys(value).every((key) => allowed.includes(key));
+}
+
+function isEmptyObject(value) {
+  return value == null || isRecord(value) && Object.keys(value).length === 0;
+}
+
+function isSafeMcpUrl(value) {
+  if (
+    typeof value !== "string"
+    || /^\p{White_Space}|\p{White_Space}$/u.test(value)
+    || /[\u0000-\u0020\u007f\\]/u.test(value)
+    || value.includes("?")
+    || value.includes("#")
+    || /%(?![0-9A-Fa-f]{2})/u.test(value)
+  ) return false;
+  const schemeSeparator = value.indexOf("://");
+  const authority = schemeSeparator >= 0 ? value.slice(schemeSeparator + 3).split("/", 1)[0] : "";
+  if (!authority || authority.includes("@") || authority.includes("%") || /[{}\x60]/u.test(authority)) return false;
+  try {
+    const url = new URL(value);
+    return ["http:", "https:"].includes(url.protocol) && Boolean(url.hostname) && !url.username && !url.password;
+  } catch {
+    return false;
+  }
+}
+
+function isCanonicalExecutionFunction(tool) {
+  return hasOnlyKeys(tool, ["type", "name", "description", "parameters", "defer_loading"])
+    && typeof tool.name === "string"
+    && typeof tool.description === "string"
+    && isRecord(tool.parameters)
+    && (tool.defer_loading === undefined || typeof tool.defer_loading === "boolean");
+}
+
+function isCanonicalExecutionMcp(tool) {
+  const transport = tool.transport;
+  const allowedTools = tool.allowed_tools;
+  return hasOnlyKeys(tool, [
+    "type", "server_label", "transport", "allowed_tools", "connection_origin",
+    "credential_id", "request_metadata", "required",
+  ])
+    && typeof tool.server_label === "string"
+    && !/^\p{White_Space}*$/u.test(tool.server_label)
+    && isRecord(transport)
+    && hasOnlyKeys(transport, ["type", "server_url", "headers"])
+    && transport.type === "http"
+    && isSafeMcpUrl(transport.server_url)
+    && isEmptyObject(transport.headers)
+    && tool.connection_origin === "service"
+    && (tool.credential_id == null || typeof tool.credential_id === "string")
+    && isEmptyObject(tool.request_metadata)
+    && (tool.required === undefined || typeof tool.required === "boolean")
+    && (allowedTools == null || Array.isArray(allowedTools) && allowedTools.every((name) => typeof name === "string" && name.length > 0));
+}
+
+function sessionAdmissionError(agent) {
+  if (/^\p{White_Space}*$/u.test(agent.model)) return "Execution currently requires a nonempty model.";
+  if (agent.multi_agent.enabled || agent.multi_agent.max_concurrent_subagents !== null) return "Enabled multi_agent execution is not supported by this service yet.";
+  if (agent.reasoning.effort != null || agent.reasoning.summary != null) return "Explicit reasoning execution options are not supported by this service yet.";
+  if (agent.service_tier !== "auto") return "Execution currently supports service_tier=auto only.";
+  if (agent.text.format.type !== "text") return "Execution currently supports text.format.type=text only.";
+
+  const functionNames = new Set();
+  const mcpLabels = new Set();
+  let functionCount = 0;
+  for (const tool of agent.tools) {
+    if (tool.type === "function") {
+      functionCount += 1;
+      if (!isCanonicalExecutionFunction(tool) || /^\p{White_Space}*$/u.test(tool.name) || Buffer.byteLength(tool.name, "utf8") > 512 || functionNames.has(tool.name) || tool.defer_loading === true) {
+        return "Invalid execution function fields.";
+      }
+      functionNames.add(tool.name);
+    } else if (tool.type === "mcp") {
+      if (!isCanonicalExecutionMcp(tool) || mcpLabels.has(tool.server_label) || tool.credential_id != null) {
+        return "Invalid execution MCP fields.";
+      }
+      mcpLabels.add(tool.server_label);
+    } else {
+      return "Execution currently supports non-deferred functions and the service-origin HTTP MCP profile only.";
+    }
+  }
+  if (functionCount > 64) return "This service supports at most 64 function tools.";
+  return null;
+}
+
 function sessionSnapshot(agent) {
   const { object: _object, metadata: _metadata, created_at: _created, updated_at: _updated, ...snapshot } = agent;
   return snapshot;
@@ -71,8 +162,10 @@ function sessionSnapshot(agent) {
 function initialState() {
   const first = savedAgent("agent_a", "Lifecycle Agent", "fixture/model-a", baseline - 60);
   const second = savedAgent("agent_b", "Second Agent", "fixture/model-b", baseline - 30);
+  const savedOnlyTool = savedAgent("agent_tool_only", "Saved-only Tool Agent", "fixture/model-tool", baseline - 20);
+  savedOnlyTool.tools = [{ type: "tool_search" }];
   return {
-    agents: [first, second],
+    agents: [first, second, savedOnlyTool],
     sessions: [{
       id: "session_snapshot",
       object: "agent.session",
@@ -90,6 +183,7 @@ function initialState() {
     turns: [],
     requests: [],
     controls: {
+      createAgentResponseVariant: "valid",
       retrieveDelayMs: 0,
       retrieveStatus: 200,
       updateDelayMs: 0,
@@ -347,11 +441,24 @@ const server = http.createServer(async (request, response) => {
 
     if (request.method === "POST" && url.pathname === "/v1/agents") {
       state.sequence += 1;
+      const defaults = savedAgent(`agent_created_${state.sequence}`, body.name ?? null, body.model, baseline + state.sequence);
       const created = {
-        ...savedAgent(`agent_created_${state.sequence}`, body.name, body.model, baseline + state.sequence),
-        instructions: body.instructions,
-        metadata: body.metadata,
+        ...defaults,
+        instructions: body.instructions ?? null,
+        metadata: body.metadata ?? {},
+        multi_agent: body.multi_agent ?? { enabled: false, max_concurrent_subagents: null },
+        reasoning: body.reasoning ?? {},
+        service_tier: body.service_tier ?? "auto",
+        text: {
+          format: body.text?.format ?? { type: "text" },
+          verbosity: body.text?.verbosity ?? "medium",
+        },
+        tools: body.tools ?? [],
       };
+      if (state.controls.createAgentResponseVariant === "reasoning") {
+        created.reasoning = { effort: "high" };
+        state.controls.createAgentResponseVariant = "valid";
+      }
       state.agents.unshift(created);
       return sendJson(response, created, 201);
     }
@@ -363,6 +470,8 @@ const server = http.createServer(async (request, response) => {
     if (request.method === "POST" && url.pathname === "/v1/agents/sessions") {
       const agent = state.agents.find((candidate) => candidate.id === body.agent_id);
       if (!agent) return sendError(response, 404, "Fixture Agent not found for Session.");
+      const admissionError = sessionAdmissionError(agent);
+      if (admissionError) return sendError(response, 400, admissionError);
       state.sequence += 1;
       const created = {
         id: `session_created_${state.sequence}`,
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index b764183..bccdca3 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -21,6 +21,7 @@ import { StatusIcon } from "./components/StatusIcon";
 import { ThemeMenu } from "./components/ThemeMenu";
 import { useToast } from "./components/Toast";
 import { AgentsView } from "./features/agents/AgentsView";
+import { knownSessionAdmissionBlocker } from "./features/agents/session-admission";
 import {
   removeSavedAgent,
   replaceSavedAgent,
@@ -869,6 +870,13 @@ export function App() {
   };
 
   const createSession = async (agentId: string) => {
+    const savedAgent = agents.find((agent) => agent.id === agentId);
+    const admissionBlocker = savedAgent ? knownSessionAdmissionBlocker(savedAgent) : "The selected saved Agent is not loaded.";
+    if (admissionBlocker) {
+      const error = new Error(`Session was not created. ${admissionBlocker}`);
+      notify(error.message, "error");
+      throw error;
+    }
     const session = await run(
       () => core.createSession({ agent_id: agentId, environment: { type: "none" }, stream: false }),
       "Idle Session created. Opening live events…",
@@ -1152,6 +1160,11 @@ export function App() {
           <span className="brand-name">Agents Core Web</span>
         </div>
 
+        <ProductNavigation
+          active={view === "system" ? null : view}
+          onSelect={(nextView) => setView(nextView)}
+        />
+
         <nav className="main-nav" aria-label="System navigation">
           <p className="nav-label">System</p>
           <button
@@ -1189,13 +1202,9 @@ export function App() {
 
       <main className="app-main" id="main-content" tabIndex={-1}>
         <header className="product-header">
-          <ProductNavigation
-            active={view === "system" ? null : view}
-            onSelect={(nextView) => setView(nextView)}
-          />
           <CreateMenu
             canCreateAgent={agentCollectionState === "ready" && !busy}
-            canStartSession={sessionCollectionState === "ready" && agents.length > 0 && !busy}
+            canStartSession={sessionCollectionState === "ready" && agents.some((agent) => !knownSessionAdmissionBlocker(agent)) && !busy}
             onCreateAgent={openAgentSetup}
             onStartSession={openSessionSetup}
           />
diff --git a/apps/web/src/components/CreateMenu.tsx b/apps/web/src/components/CreateMenu.tsx
index 0e00a52..738f84e 100644
--- a/apps/web/src/components/CreateMenu.tsx
+++ b/apps/web/src/components/CreateMenu.tsx
@@ -39,7 +39,7 @@ export function CreateMenuContent({
         <MessageSquare size={16} strokeWidth={1.5} aria-hidden="true" />
         <span>
           <strong>Start Session</strong>
-          <small>{canStartSession ? "Choose a saved Agent" : "Requires a loaded saved Agent"}</small>
+          <small>{canStartSession ? "Choose a Session-compatible saved Agent" : "Requires a loaded Session-compatible Agent"}</small>
         </span>
       </button>
     </div>
diff --git a/apps/web/src/components/ProductNavigation.test.tsx b/apps/web/src/components/ProductNavigation.test.tsx
index e93f695..e5304b2 100644
--- a/apps/web/src/components/ProductNavigation.test.tsx
+++ b/apps/web/src/components/ProductNavigation.test.tsx
@@ -10,6 +10,8 @@ describe("Product navigation", () => {
     );
 
     expect(html).toContain('aria-label="Agents product"');
+    expect(html).toContain('class="main-nav product-navigation"');
+    expect(html).toContain("Workspace");
     expect(html).toContain("Agents");
     expect(html).toContain("Environments");
     expect(html).toContain("Sessions");
diff --git a/apps/web/src/components/ProductNavigation.tsx b/apps/web/src/components/ProductNavigation.tsx
index b312c13..2b8cba7 100644
--- a/apps/web/src/components/ProductNavigation.tsx
+++ b/apps/web/src/components/ProductNavigation.tsx
@@ -1,9 +1,11 @@
+import { Bot, Boxes, MessageSquare, type LucideIcon } from "lucide-react";
+
 export type ProductView = "agents" | "environments" | "sessions";
 
-const productViews: Array<{ id: ProductView; label: string }> = [
-  { id: "agents", label: "Agents" },
-  { id: "environments", label: "Environments" },
-  { id: "sessions", label: "Sessions" },
+const productViews: Array<{ id: ProductView; label: string; icon: LucideIcon }> = [
+  { id: "agents", label: "Agents", icon: Bot },
+  { id: "environments", label: "Environments", icon: Boxes },
+  { id: "sessions", label: "Sessions", icon: MessageSquare },
 ];
 
 export function ProductNavigation({
@@ -14,18 +16,24 @@ export function ProductNavigation({
   onSelect: (view: ProductView) => void;
 }) {
   return (
-    <nav className="product-navigation" aria-label="Agents product">
-      {productViews.map((item) => (
-        <button
-          type="button"
-          className={active === item.id ? "active" : ""}
-          key={item.id}
-          onClick={() => onSelect(item.id)}
-          aria-current={active === item.id ? "page" : undefined}
-        >
-          {item.label}
-        </button>
-      ))}
+    <nav className="main-nav product-navigation" aria-label="Agents product">
+      <p className="nav-label">Workspace</p>
+      {productViews.map((item) => {
+        const Icon = item.icon;
+        return (
+          <button
+            type="button"
+            className={active === item.id ? "active" : ""}
+            key={item.id}
+            onClick={() => onSelect(item.id)}
+            aria-label={item.label}
+            aria-current={active === item.id ? "page" : undefined}
+          >
+            <Icon size={15} strokeWidth={1.5} aria-hidden="true" />
+            <span>{item.label}</span>
+          </button>
+        );
+      })}
     </nav>
   );
 }
diff --git a/apps/web/src/features/agents/AgentForm.tsx b/apps/web/src/features/agents/AgentForm.tsx
index 7762040..691775f 100644
--- a/apps/web/src/features/agents/AgentForm.tsx
+++ b/apps/web/src/features/agents/AgentForm.tsx
@@ -41,8 +41,10 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
   const [serviceTier, setServiceTier] = useState(initial.serviceTier);
   const [textFormat] = useState(initial.textFormat);
   const [textVerbosity, setTextVerbosity] = useState(initial.textVerbosity);
+  const [configurationError, setConfigurationError] = useState<string | null>(null);
   const [modelError, setModelError] = useState<string | null>(null);
   const [metadataError, setMetadataError] = useState<string | null>(null);
+  const [nameError, setNameError] = useState<string | null>(null);
   const model = modelChoice === CUSTOM_MODEL_OPTION ? customModel : modelIdFromOption(modelChoice) ?? "";
 
   useEffect(() => {
@@ -77,8 +79,10 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
       textFormat,
       textVerbosity,
     }, agent ? "update" : "create");
+    setConfigurationError(result.configurationError ?? null);
     setModelError(result.modelError ?? null);
     setMetadataError(result.metadataError ?? null);
+    setNameError(result.nameError ?? null);
     if (!result.input) return;
     await onSubmit(result.input);
   };
@@ -91,10 +95,17 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
         <input
           ref={nameRef}
           value={name}
-          onChange={(event) => setName(event.target.value)}
+          onChange={(event) => {
+            setName(event.target.value);
+            if (nameError) setNameError(null);
+          }}
           placeholder="Repository builder"
           data-agent-initial-focus="true"
+          aria-describedby={`${formId}-name-help${nameError ? ` ${formId}-name-error` : ""}`}
+          aria-invalid={Boolean(nameError)}
         />
+        <small id={`${formId}-name-help`}>Optional. Agent Core accepts at most 128 Unicode characters.</small>
+        {nameError ? <small className="field-error" id={`${formId}-name-error`} role="alert">{nameError}</small> : null}
       </label>
       <label className="field">
         <span>Instructions</span>
@@ -172,12 +183,17 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
               aria-describedby={`${formId}-text-format-help`}
             />
             <small id={`${formId}-text-format-help`}>
-              Displayed from the Agent contract. This Web preserves JSON schemas but does not edit them yet.
+              Current Web-created Sessions use text. Existing JSON schemas are preserved read-only and block Session start.
             </small>
           </label>
           <label className="field">
             <span>Reasoning effort</span>
-            <select value={reasoningEffort} onChange={(event) => setReasoningEffort(event.target.value as typeof reasoningEffort)}>
+            <select
+              value={reasoningEffort}
+              onChange={(event) => setReasoningEffort(event.target.value as typeof reasoningEffort)}
+              aria-describedby={`${formId}-generation-profile-help`}
+              disabled={!agent}
+            >
               <option value="">Core default</option>
               {(["none", "minimal", "low", "medium", "high", "xhigh", "max"] as const).map((value) => (
                 <option value={value} key={value}>{value}</option>
@@ -186,7 +202,12 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
           </label>
           <label className="field">
             <span>Text verbosity</span>
-            <select value={textVerbosity} onChange={(event) => setTextVerbosity(event.target.value as typeof textVerbosity)}>
+            <select
+              value={textVerbosity}
+              onChange={(event) => setTextVerbosity(event.target.value as typeof textVerbosity)}
+              aria-describedby={`${formId}-generation-profile-help`}
+              disabled={!agent}
+            >
               {(["low", "medium", "high"] as const).map((value) => (
                 <option value={value} key={value}>{value}</option>
               ))}
@@ -194,7 +215,12 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
           </label>
           <label className="field">
             <span>Reasoning summary</span>
-            <select value={reasoningSummary} onChange={(event) => setReasoningSummary(event.target.value as typeof reasoningSummary)}>
+            <select
+              value={reasoningSummary}
+              onChange={(event) => setReasoningSummary(event.target.value as typeof reasoningSummary)}
+              aria-describedby={`${formId}-generation-profile-help`}
+              disabled={!agent}
+            >
               <option value="">Core default</option>
               {(["concise", "detailed", "auto"] as const).map((value) => (
                 <option value={value} key={value}>{value}</option>
@@ -203,29 +229,38 @@ export function AgentForm({ agent, disabled = false, formId, knownModels, onDraf
           </label>
           <label className="field">
             <span>Service tier</span>
-            <select value={serviceTier} onChange={(event) => setServiceTier(event.target.value as typeof serviceTier)}>
+            <select
+              value={serviceTier}
+              onChange={(event) => setServiceTier(event.target.value as typeof serviceTier)}
+              aria-describedby={`${formId}-generation-profile-help`}
+              disabled={!agent}
+            >
               {(["auto", "default", "flex", "priority", "fast"] as const).map((value) => (
                 <option value={value} key={value}>{value}</option>
               ))}
             </select>
           </label>
         </div>
-        <p className="agent-form-capability-note">
-          These fields are saved by Agent Core. The connected executor, model, and provider may support a narrower set; the first real Turn remains authoritative.
+        <p className="agent-form-capability-note" id={`${formId}-generation-profile-help`}>
+          New Agents use the current cross-engine Session profile: implicit reasoning, medium verbosity, service tier auto, and text format. Existing saved-only values remain visible; reasoning, verbosity, and tier stay editable, while known incompatible settings block Session start. Model and provider compatibility still require a real Turn.
         </p>
+        {configurationError ? <p className="field-error" role="alert">{configurationError}</p> : null}
       </section>
       <label className="field">
         <span>Metadata</span>
         <textarea
           className="agent-metadata-input"
           value={metadata}
-          onChange={(event) => setMetadata(event.target.value)}
+          onChange={(event) => {
+            setMetadata(event.target.value);
+            if (metadataError) setMetadataError(null);
+          }}
           rows={5}
           spellCheck={false}
           aria-describedby={`${formId}-metadata-help${metadataError ? ` ${formId}-metadata-error` : ""}`}
           aria-invalid={Boolean(metadataError)}
         />
-        <small id={`${formId}-metadata-help`}>JSON object with string values only. Never store secrets in Agent metadata.</small>
+        <small id={`${formId}-metadata-help`}>JSON object with at most 16 string pairs; keys are limited to 64 characters and values to 512. Never store secrets in Agent metadata.</small>
         {metadataError ? <small className="field-error" id={`${formId}-metadata-error`} role="alert">{metadataError}</small> : null}
       </label>
       </fieldset>
diff --git a/apps/web/src/features/agents/AgentSetupView.test.tsx b/apps/web/src/features/agents/AgentSetupView.test.tsx
index 81f093e..b4f8704 100644
--- a/apps/web/src/features/agents/AgentSetupView.test.tsx
+++ b/apps/web/src/features/agents/AgentSetupView.test.tsx
@@ -23,9 +23,11 @@ describe("Agent setup page", () => {
     expect(html).toContain("${AGENTS_CORE_API_KEY}");
     expect(html).toContain("Get started creating an Agent");
     expect(html).toContain("Text format");
-    expect(html).toContain("This Web preserves JSON schemas but does not edit them yet");
+    expect(html).toContain("Existing JSON schemas are preserved read-only and block Session start");
     expect(html).toContain("Reasoning effort");
     expect(html).toContain("Text verbosity");
+    expect(html).toContain("current cross-engine Session profile");
+    expect(html).not.toContain("&quot;reasoning&quot;");
     expect(html.indexOf(">Name<")).toBeLessThan(html.indexOf(">Instructions<"));
     expect(html.indexOf(">Instructions<")).toBeLessThan(html.indexOf(">Model<"));
     expect(html).not.toContain("manual-token");
diff --git a/apps/web/src/features/agents/AgentSetupView.tsx b/apps/web/src/features/agents/AgentSetupView.tsx
index 0e3ec8c..c3fe818 100644
--- a/apps/web/src/features/agents/AgentSetupView.tsx
+++ b/apps/web/src/features/agents/AgentSetupView.tsx
@@ -6,6 +6,7 @@ import type { CreateAgentInput, SavedAgent } from "@agents-core-web/agents-clien
 import { AgentForm } from "./AgentForm";
 import { buildAgentRequestPreview } from "./agent-preview";
 import { valuesFromAgent } from "./agent-form";
+import { knownSessionAdmissionBlocker } from "./session-admission";
 
 function AgentRequestPreview({
   baseUrl,
@@ -38,7 +39,7 @@ function AgentRequestPreview({
 
 function SetupGuide({ saved }: { saved: boolean }) {
   const steps = [
-    ["Define an Agent", "Choose a model, instructions, and supported generation settings.", true],
+    ["Define an Agent", "Choose a model and instructions; the Web keeps generation settings on the current Session-safe profile.", true],
     ["Save the definition", "Core becomes the durable source of truth for the saved Agent.", saved],
     ["Start a Session", "Create an idle environment:none Session and subscribe before sending input.", false],
     ["Exchange events", "A real Turn still requires a compatible worker, executor, model, and provider.", false],
@@ -78,6 +79,7 @@ export function AgentSetupView({
   const [draft, setDraft] = useState(() => valuesFromAgent());
   const [created, setCreated] = useState<SavedAgent | null>(null);
   const formId = "create-agent";
+  const sessionAdmissionBlocker = created ? knownSessionAdmissionBlocker(created) : null;
 
   const create = async (input: CreateAgentInput) => {
     const agent = await onCreate(input);
@@ -111,6 +113,11 @@ export function AgentSetupView({
               Agent definition saved as <code>{created.id}</code>. This does not prove execution readiness.
             </div>
           ) : null}
+          {sessionAdmissionBlocker ? (
+            <div className="notice warning" id="created-agent-session-blocker" role="note">
+              Saved successfully, but Start Session is unavailable. {sessionAdmissionBlocker}
+            </div>
+          ) : null}
           <AgentForm
             disabled={busy || Boolean(created)}
             formId={formId}
@@ -126,7 +133,8 @@ export function AgentSetupView({
             <button
               className="button primary agent-start-session"
               type="button"
-              disabled={busy || !created}
+              disabled={busy || !created || Boolean(sessionAdmissionBlocker)}
+              aria-describedby={sessionAdmissionBlocker ? "created-agent-session-blocker" : undefined}
               onClick={() => created && onStartSession(created.id)}
             >
               <MessageSquare size={14} strokeWidth={1.5} aria-hidden="true" />
diff --git a/apps/web/src/features/agents/AgentsView.test.tsx b/apps/web/src/features/agents/AgentsView.test.tsx
index 0052316..3c2724f 100644
--- a/apps/web/src/features/agents/AgentsView.test.tsx
+++ b/apps/web/src/features/agents/AgentsView.test.tsx
@@ -35,7 +35,7 @@ describe("Agents view", () => {
     expect(html).toContain("Text");
     expect(html).toContain("Service tier");
     expect(html).toContain("Multi-agent");
-    expect(html).toContain("does not prove the current executor");
+    expect(html).toContain("known Core Session profile cannot start it");
     expect(html).not.toMatch(/<(input|textarea|select)/);
   });
 
@@ -51,7 +51,7 @@ describe("Agents view", () => {
     expect(html).toContain("provider/model");
   });
 
-  it("uses native keyboard-operable buttons for Agent details and Session start", () => {
+  it("fails closed for a saved-only Agent configuration", () => {
     const html = renderToStaticMarkup(
       <AgentsView
         agents={[agent]}
@@ -65,7 +65,33 @@ describe("Agents view", () => {
     );
 
     expect(html).toContain('type="button" aria-label="Open details for this Agent"');
+    expect(html).toContain('aria-disabled="true" aria-label="Start a Session with this Agent"');
+    expect(html).toContain("Session unavailable: Current Core Session admission requires");
+  });
+
+  it("keeps Session start available for the known admission profile", () => {
+    const compatible = {
+      ...agent,
+      multi_agent: { enabled: false, max_concurrent_subagents: null },
+      reasoning: {},
+      service_tier: "auto" as const,
+      text: { format: { type: "text" as const }, verbosity: "medium" as const },
+      tools: [],
+    };
+    const html = renderToStaticMarkup(
+      <AgentsView
+        agents={[compatible]}
+        busy={false}
+        coreError={null}
+        coreState="ready"
+        onCreate={async () => undefined}
+        onRefresh={() => undefined}
+        onStartSession={async () => undefined}
+      />,
+    );
+
     expect(html).toContain('type="button" aria-label="Start a Session with this Agent"');
+    expect(html).not.toContain("Session unavailable:");
   });
 
   it("states the durable delete boundary before confirmation", () => {
diff --git a/apps/web/src/features/agents/AgentsView.tsx b/apps/web/src/features/agents/AgentsView.tsx
index 828ee37..60f5fce 100644
--- a/apps/web/src/features/agents/AgentsView.tsx
+++ b/apps/web/src/features/agents/AgentsView.tsx
@@ -10,6 +10,7 @@ import { AgentDialog } from "./AgentDialog";
 import { AgentForm } from "./AgentForm";
 import { AgentSetupView } from "./AgentSetupView";
 import { createRequestGate } from "./agent-form";
+import { knownSessionAdmissionBlocker } from "./session-admission";
 
 interface AgentsViewProps {
   agents: SavedAgent[];
@@ -67,7 +68,41 @@ function StructuredValue({ value }: { value: unknown }) {
   return <pre className="agent-structured-value">{JSON.stringify(value, null, 2)}</pre>;
 }
 
+function AgentSessionStartAction({
+  agent,
+  busy,
+  onStart,
+}: {
+  agent: SavedAgent;
+  busy: boolean;
+  onStart: (agentId: string) => void;
+}) {
+  const blocker = knownSessionAdmissionBlocker(agent);
+  const descriptionId = `start-session-${agent.id}`;
+  return (
+    <span className="action-tooltip">
+      <button
+        className="icon-button ghost agent-session-start"
+        type="button"
+        onClick={() => {
+          if (!blocker) onStart(agent.id);
+        }}
+        disabled={busy}
+        aria-disabled={blocker ? true : undefined}
+        aria-label={`Start a Session with ${agent.name || "this Agent"}`}
+        aria-describedby={descriptionId}
+      >
+        <MessageSquare size={14} strokeWidth={1.5} />
+      </button>
+      <span className="action-tooltip-content" role="tooltip" id={descriptionId}>
+        {blocker ? `Session unavailable: ${blocker}` : "Start Session"}
+      </span>
+    </span>
+  );
+}
+
 export function AgentDetails({ agent }: { agent: SavedAgent }) {
+  const blocker = knownSessionAdmissionBlocker(agent);
   return (
     <div className="agent-details">
       <div className="agent-detail-summary">
@@ -82,7 +117,9 @@ export function AgentDetails({ agent }: { agent: SavedAgent }) {
         </dl>
       </div>
       <div className="agent-capability-warning" role="note">
-        Saved advanced configuration is capability information only. It does not prove the current executor supports or can run tools, multi-agent, MCP, web search, plugins, reasoning, text, or service-tier settings.
+        {blocker
+          ? `This Agent can be saved, but the known Core Session profile cannot start it: ${blocker}`
+          : "Saved advanced configuration is not runtime proof. Model, provider, host, tools, and conditional verbosity still require executor validation."}
       </div>
       <section className="agent-capabilities" aria-labelledby="agent-capabilities-title">
         <h3 id="agent-capabilities-title">Advanced configuration · read only</h3>
@@ -351,19 +388,7 @@ export function AgentsView({
                 <span className="ledger-number" role="cell">{agent.tools.length}</span>
                 <span className="ledger-age" role="cell">{formatShortDate(agent.updated_at)}</span>
                 <span className="ledger-actions" role="cell">
-                  <span className="action-tooltip">
-                    <button
-                      className="icon-button ghost"
-                      type="button"
-                      onClick={() => startSession(agent.id)}
-                      disabled={busy}
-                      aria-label={`Start a Session with ${agent.name || "this Agent"}`}
-                      aria-describedby={`start-session-${agent.id}`}
-                    >
-                      <MessageSquare size={14} strokeWidth={1.5} />
-                    </button>
-                    <span className="action-tooltip-content" role="tooltip" id={`start-session-${agent.id}`}>Start Session</span>
-                  </span>
+                  <AgentSessionStartAction agent={agent} busy={busy} onStart={startSession} />
                 </span>
               </div>
             ))}
diff --git a/apps/web/src/features/agents/agent-form.test.ts b/apps/web/src/features/agents/agent-form.test.ts
index 89383e4..ef30eb2 100644
--- a/apps/web/src/features/agents/agent-form.test.ts
+++ b/apps/web/src/features/agents/agent-form.test.ts
@@ -3,7 +3,7 @@ import { describe, expect, it } from "vitest";
 import { createRequestGate, validateAgentForm, valuesFromAgent } from "./agent-form";
 
 describe("Agent form contract", () => {
-  it("uses explicit nulls for blank nullable fields and preserves string metadata", () => {
+  it("uses the current Session-safe defaults and omits implicit reasoning", () => {
     const result = validateAgentForm({
       ...valuesFromAgent(),
       model: "  provider/model  ",
@@ -18,11 +18,11 @@ describe("Agent form contract", () => {
         name: null,
         instructions: null,
         metadata: { team: "web", owner: "sam" },
-        reasoning: { effort: "medium", summary: "auto" },
         service_tier: "auto",
         text: { format: { type: "text" }, verbosity: "medium" },
       },
     });
+    expect(result.input).not.toHaveProperty("reasoning");
   });
 
   it.each([
@@ -36,6 +36,48 @@ describe("Agent form contract", () => {
     });
   });
 
+  it("matches Core's Unicode whitespace rule for required models", () => {
+    expect(validateAgentForm({ ...valuesFromAgent(), model: "\u0085" })).toEqual({ modelError: "Enter a model ID." });
+  });
+
+  it("matches Core's Unicode name and metadata boundaries", () => {
+    const base = { ...valuesFromAgent(), model: "model" };
+    const sixteen = Object.fromEntries(Array.from({ length: 16 }, (_, index) => [`key-${index}`, "value"]));
+
+    expect(validateAgentForm({ ...base, name: "😀".repeat(128), metadata: JSON.stringify(sixteen) }).input).toBeDefined();
+    expect(validateAgentForm({ ...base, name: "😀".repeat(129) })).toEqual({
+      nameError: "Name must be at most 128 characters.",
+    });
+    expect(validateAgentForm({
+      ...base,
+      metadata: JSON.stringify({ ...sixteen, extra: "value" }),
+    })).toEqual({ metadataError: "Agent metadata supports at most 16 pairs." });
+    expect(validateAgentForm({
+      ...base,
+      metadata: JSON.stringify({ ["😀".repeat(64)]: "😀".repeat(512) }),
+    }).input).toBeDefined();
+    expect(validateAgentForm({
+      ...base,
+      metadata: JSON.stringify({ ["😀".repeat(65)]: "value" }),
+    })).toEqual({ metadataError: "Metadata keys must be at most 64 characters and values at most 512 characters." });
+    expect(validateAgentForm({
+      ...base,
+      metadata: JSON.stringify({ key: "😀".repeat(513) }),
+    })).toEqual({ metadataError: "Metadata keys must be at most 64 characters and values at most 512 characters." });
+  });
+
+  it.each([
+    [{ reasoningEffort: "none" as const }, "Current Core Sessions require both reasoning fields to use Core default."],
+    [{ reasoningSummary: "auto" as const }, "Current Core Sessions require both reasoning fields to use Core default."],
+    [{ serviceTier: "priority" as const }, "Current Core Sessions support service tier auto only."],
+    [{ textFormat: { type: "json_schema" as const, schema: {} } }, "Current Core Sessions support text format only."],
+    [{ textVerbosity: "high" as const }, "Low and high verbosity require a discovered compatible Codex model; use medium for this Web flow."],
+  ])("fails closed before creating a saved Agent that the Web cannot safely continue", (change, message) => {
+    const result = validateAgentForm({ ...valuesFromAgent(), model: "model", ...change });
+    expect(result).toEqual({ configurationError: message });
+    expect(result.input).toBeUndefined();
+  });
+
   it("round-trips existing nullable values into editable fields without inventing data", () => {
     expect(valuesFromAgent({
       id: "agent_1",
diff --git a/apps/web/src/features/agents/agent-form.ts b/apps/web/src/features/agents/agent-form.ts
index 4a82070..8e0d644 100644
--- a/apps/web/src/features/agents/agent-form.ts
+++ b/apps/web/src/features/agents/agent-form.ts
@@ -7,6 +7,8 @@ import type {
   SavedAgent,
 } from "@agents-core-web/agents-client";
 
+import { isCoreWhitespaceOnly } from "./session-admission";
+
 export type TextVerbosity = "low" | "medium" | "high";
 
 export interface AgentFormValues {
@@ -22,9 +24,11 @@ export interface AgentFormValues {
 }
 
 export interface AgentFormValidation {
+  configurationError?: string;
   input?: CreateAgentInput;
   metadataError?: string;
   modelError?: string;
+  nameError?: string;
 }
 
 export type AgentFormIntent = "create" | "update";
@@ -35,8 +39,8 @@ export function valuesFromAgent(agent?: SavedAgent): AgentFormValues {
     model: agent?.model ?? "",
     instructions: agent?.instructions ?? "",
     metadata: JSON.stringify(agent?.metadata ?? {}, null, 2),
-    reasoningEffort: agent ? agent.reasoning.effort ?? "" : "medium",
-    reasoningSummary: agent ? agent.reasoning.summary ?? "" : "auto",
+    reasoningEffort: agent?.reasoning.effort ?? "",
+    reasoningSummary: agent?.reasoning.summary ?? "",
     serviceTier: agent?.service_tier ?? "auto",
     textFormat: agent?.text.format ?? { type: "text" },
     textVerbosity: agent?.text.verbosity ?? "medium",
@@ -48,7 +52,12 @@ export function validateAgentForm(
   intent: AgentFormIntent = "create",
 ): AgentFormValidation {
   const model = values.model.trim();
-  if (!model) return { modelError: "Enter a model ID." };
+  if (isCoreWhitespaceOnly(model)) return { modelError: "Enter a model ID." };
+
+  const name = values.name.trim();
+  if ([...name].length > 128) {
+    return { nameError: "Name must be at most 128 characters." };
+  }
 
   let parsed: unknown;
   try {
@@ -65,10 +74,32 @@ export function validateAgentForm(
   if (Object.values(metadata).some((value) => typeof value !== "string")) {
     return { metadataError: "Every metadata value must be a string." };
   }
+  const metadataEntries = Object.entries(metadata) as [string, string][];
+  if (metadataEntries.length > 16) {
+    return { metadataError: "Agent metadata supports at most 16 pairs." };
+  }
+  if (metadataEntries.some(([key, value]) => [...key].length > 64 || [...value].length > 512)) {
+    return { metadataError: "Metadata keys must be at most 64 characters and values at most 512 characters." };
+  }
+
+  if (intent === "create") {
+    if (values.reasoningEffort || values.reasoningSummary) {
+      return { configurationError: "Current Core Sessions require both reasoning fields to use Core default." };
+    }
+    if (values.serviceTier !== "auto") {
+      return { configurationError: "Current Core Sessions support service tier auto only." };
+    }
+    if (values.textFormat.type !== "text") {
+      return { configurationError: "Current Core Sessions support text format only." };
+    }
+    if (values.textVerbosity !== "medium") {
+      return { configurationError: "Low and high verbosity require a discovered compatible Codex model; use medium for this Web flow." };
+    }
+  }
 
   const input: CreateAgentInput = {
     model,
-    name: values.name.trim() || null,
+    name: name || null,
     instructions: values.instructions.trim() || null,
     metadata: metadata as Record<string, string>,
     service_tier: values.serviceTier,
diff --git a/apps/web/src/features/agents/agent-preview.test.ts b/apps/web/src/features/agents/agent-preview.test.ts
index f958e48..157100d 100644
--- a/apps/web/src/features/agents/agent-preview.test.ts
+++ b/apps/web/src/features/agents/agent-preview.test.ts
@@ -15,11 +15,23 @@ describe("Agent request preview", () => {
     expect(preview.curl).toContain(previewTokenPlaceholder);
     expect(preview.curl).toContain("@agent.json");
     expect(preview.curl).not.toContain("live-caller-secret");
-    expect(JSON.parse(preview.json)).toMatchObject({
+    const body = JSON.parse(preview.json);
+    expect(body).toMatchObject({
       model: "provider/model",
-      reasoning: { effort: "medium", summary: "auto" },
+      service_tier: "auto",
       text: { format: { type: "text" }, verbosity: "medium" },
     });
+    expect(body).not.toHaveProperty("reasoning");
+  });
+
+  it("shows an explicitly saved-only value instead of silently deleting it", () => {
+    const preview = buildAgentRequestPreview({
+      ...valuesFromAgent(),
+      model: "provider/model",
+      reasoningEffort: "high",
+    }, "/v1");
+
+    expect(JSON.parse(preview.json)).toMatchObject({ reasoning: { effort: "high" } });
   });
 
   it("does not echo unsafe URL credentials or query values", () => {
diff --git a/apps/web/src/features/agents/session-admission.test.ts b/apps/web/src/features/agents/session-admission.test.ts
new file mode 100644
index 0000000..fc81b4c
--- /dev/null
+++ b/apps/web/src/features/agents/session-admission.test.ts
@@ -0,0 +1,130 @@
+import { describe, expect, it } from "vitest";
+
+import type { SavedAgent } from "@agents-core-web/agents-client";
+
+import { knownSessionAdmissionBlocker, knownSessionAdmissionBlockers } from "./session-admission";
+
+const executableAgent: SavedAgent = {
+  id: "agent_1",
+  object: "agent",
+  model: "provider/model",
+  name: null,
+  instructions: null,
+  metadata: {},
+  multi_agent: { enabled: false, max_concurrent_subagents: null },
+  reasoning: {},
+  service_tier: "auto",
+  text: { format: { type: "text" }, verbosity: "medium" },
+  tools: [],
+  created_at: 1,
+  updated_at: 1,
+};
+
+const executableMcp = {
+  type: "mcp",
+  server_label: "docs",
+  transport: { type: "http", server_url: "https://mcp.example/tools", headers: {} },
+  allowed_tools: null,
+  connection_origin: "service",
+  credential_id: null,
+  request_metadata: {},
+  required: false,
+};
+
+describe("known Session admission blockers", () => {
+  it("accepts the current safe profile without claiming runtime readiness", () => {
+    expect(knownSessionAdmissionBlockers(executableAgent)).toEqual([]);
+    expect(knownSessionAdmissionBlocker(executableAgent)).toBeNull();
+  });
+
+  it.each([
+    [{ reasoning: { effort: "none" as const } }, "explicit reasoning options are saved-only"],
+    [{ reasoning: { summary: "auto" as const } }, "explicit reasoning options are saved-only"],
+    [{ service_tier: "priority" as const }, "service tier must be auto"],
+    [{ text: { format: { type: "json_schema" as const, schema: { type: "object" } }, verbosity: "medium" as const } }, "text format must be text"],
+    [{ multi_agent: { enabled: true, max_concurrent_subagents: 2 } }, "multi-agent execution is not supported"],
+    [{ tools: [{ type: "tool_search" }] }, "tool_search is saved-only"],
+    [{ tools: [{ type: "function", name: "later", description: "", parameters: {}, defer_loading: true }] }, "deferred functions are saved-only"],
+    [{ tools: [{ type: "function", name: " ", description: "", parameters: {}, defer_loading: false }] }, "function names must be non-empty and at most 512 bytes"],
+    [{ tools: [{ type: "function", name: "\u0085", description: "", parameters: {}, defer_loading: false }] }, "function names must be non-empty and at most 512 bytes"],
+    [{ tools: [{ type: "function", name: "😀".repeat(129), description: "", parameters: {}, defer_loading: false }] }, "function names must be non-empty and at most 512 bytes"],
+    [{ tools: [{ ...executableMcp, credential_id: "credential-id" }] }, "attached MCP credentials are unavailable in this Web Session flow"],
+    [{ tools: [{ type: "function" }] }, "the saved function tool is incomplete or malformed"],
+    [{ tools: [{ type: "function", name: "run", description: "", parameters: [] }] }, "the saved function tool is incomplete or malformed"],
+    [{ tools: [{ type: "function", name: "run", description: "", parameters: {}, defer_loading: "false" }] }, "the saved function tool is incomplete or malformed"],
+    [{ tools: [{ type: "function", name: "run", description: "", parameters: {}, extra: true }] }, "the saved function tool is incomplete or malformed"],
+    [{ tools: [{ type: "mcp" }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://user:secret@mcp.example/tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: " https://mcp.example/tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https:\\mcp.example\\tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://@mcp.example/tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://mcp.example/%zz" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://mcp.example/%" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://%65xample.com/tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, server_url: "https://exa{mple}.com/tools" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, transport: { ...executableMcp.transport, headers: { Authorization: "secret" } } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, connection_origin: "browser" }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, request_metadata: { secret: "value" } }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, allowed_tools: [""] }] }, "the saved MCP tool is incomplete or malformed"],
+    [{ tools: [{ ...executableMcp, required: "false" }] }, "the saved MCP tool is incomplete or malformed"],
+  ])("blocks a known unsupported saved configuration", (change, message) => {
+    const agent = { ...executableAgent, ...change } as SavedAgent;
+    expect(knownSessionAdmissionBlockers(agent)).toContain(message);
+  });
+
+  it("does not turn conditional Codex verbosity support into a deterministic blocker", () => {
+    const agent = { ...executableAgent, text: { ...executableAgent.text, verbosity: "high" as const } };
+    expect(knownSessionAdmissionBlocker(agent)).toBeNull();
+  });
+
+  it("accepts the canonical anonymous service-origin HTTP MCP shape", () => {
+    expect(knownSessionAdmissionBlocker({ ...executableAgent, tools: [executableMcp] })).toBeNull();
+  });
+
+  it("accepts canonical function and MCP variants that Core admits", () => {
+    expect(knownSessionAdmissionBlocker({
+      ...executableAgent,
+      tools: [{ type: "function", name: "lookup", description: "", parameters: {}, defer_loading: false }],
+    })).toBeNull();
+    expect(knownSessionAdmissionBlocker({
+      ...executableAgent,
+      tools: [{ ...executableMcp, required: true, transport: { ...executableMcp.transport, server_url: "https://mcp.example/a%2Fb" } }],
+    })).toBeNull();
+    const { allowed_tools: _allowedTools, credential_id: _credentialId, request_metadata: _requestMetadata, required: _required, ...mcpWithDefaultsOmitted } = executableMcp;
+    expect(knownSessionAdmissionBlocker({ ...executableAgent, tools: [mcpWithDefaultsOmitted] })).toBeNull();
+  });
+
+  it("matches Core's case-insensitive URL scheme parsing", () => {
+    const uppercaseScheme = {
+      ...executableMcp,
+      transport: { ...executableMcp.transport, server_url: "HTTPS://mcp.example/tools" },
+    };
+    expect(knownSessionAdmissionBlocker({ ...executableAgent, tools: [uppercaseScheme] })).toBeNull();
+  });
+
+  it("blocks duplicate and over-limit execution tool identifiers", () => {
+    const fn = { type: "function", name: "lookup", description: "", parameters: {}, defer_loading: false };
+    expect(knownSessionAdmissionBlockers({ ...executableAgent, tools: [fn, fn] })).toContain("function names must be unique");
+    expect(knownSessionAdmissionBlockers({
+      ...executableAgent,
+      tools: Array.from({ length: 65 }, (_, index) => ({ ...fn, name: `lookup_${index}` })),
+    })).toContain("at most 64 function tools can execute");
+    expect(knownSessionAdmissionBlockers({ ...executableAgent, tools: [executableMcp, executableMcp] })).toContain("MCP server labels must be unique");
+  });
+
+  it("reports every deterministic blocker without implying they are runtime-discovered", () => {
+    const blockers = knownSessionAdmissionBlockers({
+      ...executableAgent,
+      model: " ",
+      reasoning: { effort: "high", summary: "detailed" },
+      service_tier: "flex",
+      text: { format: { type: "json_schema", schema: {} }, verbosity: "low" },
+    });
+    expect(blockers).toEqual([
+      "a non-empty model is required",
+      "explicit reasoning options are saved-only",
+      "service tier must be auto",
+      "text format must be text",
+    ]);
+  });
+});
diff --git a/apps/web/src/features/agents/session-admission.ts b/apps/web/src/features/agents/session-admission.ts
new file mode 100644
index 0000000..2503a29
--- /dev/null
+++ b/apps/web/src/features/agents/session-admission.ts
@@ -0,0 +1,134 @@
+import type { SavedAgent } from "@agents-core-web/agents-client";
+
+// Go strings.TrimSpace uses unicode.IsSpace, whose White_Space set includes U+0085.
+export function isCoreWhitespaceOnly(value: string): boolean {
+  return /^\p{White_Space}*$/u.test(value);
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
+}
+
+function hasOnlyKeys(value: Record<string, unknown>, allowed: readonly string[]): boolean {
+  return Object.keys(value).every((key) => allowed.includes(key));
+}
+
+function isEmptyObject(value: unknown): boolean {
+  return value == null || isRecord(value) && Object.keys(value).length === 0;
+}
+
+function isSafeMcpUrl(value: unknown): boolean {
+  if (
+    typeof value !== "string"
+    || /^\p{White_Space}|\p{White_Space}$/u.test(value)
+    || /[\u0000-\u0020\u007f\\]/u.test(value)
+    || value.includes("?")
+    || value.includes("#")
+    || /%(?![0-9A-Fa-f]{2})/u.test(value)
+  ) return false;
+  const schemeSeparator = value.indexOf("://");
+  const authority = schemeSeparator >= 0 ? value.slice(schemeSeparator + 3).split("/", 1)[0] : "";
+  // Go's net/url rejects escaped ASCII and raw braces/backticks in a host,
+  // while WHATWG URL may decode or preserve them and silently accept it.
+  if (!authority || authority.includes("@") || authority.includes("%") || /[{}\x60]/u.test(authority)) return false;
+  try {
+    const url = new URL(value);
+    return ["http:", "https:"].includes(url.protocol) && Boolean(url.hostname) && !url.username && !url.password;
+  } catch {
+    return false;
+  }
+}
+
+function isCanonicalExecutionFunction(tool: Record<string, unknown>): boolean {
+  return hasOnlyKeys(tool, ["type", "name", "description", "parameters", "defer_loading"])
+    && typeof tool.name === "string"
+    && typeof tool.description === "string"
+    && isRecord(tool.parameters)
+    && (tool.defer_loading === undefined || typeof tool.defer_loading === "boolean");
+}
+
+function isCanonicalExecutionMcp(tool: Record<string, unknown>): boolean {
+  const transport = tool.transport;
+  const allowedTools = tool.allowed_tools;
+  return hasOnlyKeys(tool, [
+    "type", "server_label", "transport", "allowed_tools", "connection_origin",
+    "credential_id", "request_metadata", "required",
+  ])
+    && typeof tool.server_label === "string"
+    && !isCoreWhitespaceOnly(tool.server_label)
+    && isRecord(transport)
+    && hasOnlyKeys(transport, ["type", "server_url", "headers"])
+    && transport.type === "http"
+    && isSafeMcpUrl(transport.server_url)
+    && isEmptyObject(transport.headers)
+    && tool.connection_origin === "service"
+    && (tool.credential_id == null || typeof tool.credential_id === "string")
+    && isEmptyObject(tool.request_metadata)
+    && (tool.required === undefined || typeof tool.required === "boolean")
+    && (allowedTools == null || Array.isArray(allowedTools) && allowedTools.every((name) => typeof name === "string" && name.length > 0));
+}
+
+/**
+ * Deterministic Saved Agent blockers enforced by Parsar before Session persistence.
+ * A null result is not execution-readiness proof: model, provider, host, tools, and
+ * non-default verbosity can still require runtime validation.
+ */
+export function knownSessionAdmissionBlockers(agent: SavedAgent): string[] {
+  const blockers: string[] = [];
+  if (isCoreWhitespaceOnly(agent.model)) blockers.push("a non-empty model is required");
+  if (agent.multi_agent.enabled || agent.multi_agent.max_concurrent_subagents !== null) {
+    blockers.push("multi-agent execution is not supported");
+  }
+  if (agent.reasoning.effort != null || agent.reasoning.summary != null) {
+    blockers.push("explicit reasoning options are saved-only");
+  }
+  if (agent.service_tier !== "auto") blockers.push("service tier must be auto");
+  if (agent.text.format.type !== "text") blockers.push("text format must be text");
+
+  const functionNames = new Set<string>();
+  const mcpLabels = new Set<string>();
+  let functionCount = 0;
+  for (const rawTool of agent.tools) {
+    if (!rawTool || typeof rawTool !== "object" || Array.isArray(rawTool)) {
+      blockers.push("the saved tool configuration is not executable");
+      continue;
+    }
+    const tool = rawTool as Record<string, unknown>;
+    switch (tool.type) {
+      case "function": {
+        functionCount += 1;
+        if (!isCanonicalExecutionFunction(tool)) blockers.push("the saved function tool is incomplete or malformed");
+        if (tool.defer_loading === true) blockers.push("deferred functions are saved-only");
+        if (typeof tool.name === "string") {
+          if (isCoreWhitespaceOnly(tool.name) || new TextEncoder().encode(tool.name).length > 512) {
+            blockers.push("function names must be non-empty and at most 512 bytes");
+          }
+          if (functionNames.has(tool.name)) blockers.push("function names must be unique");
+          functionNames.add(tool.name);
+        }
+        break;
+      }
+      case "mcp":
+        if (!isCanonicalExecutionMcp(tool)) blockers.push("the saved MCP tool is incomplete or malformed");
+        if (tool.credential_id != null) blockers.push("attached MCP credentials are unavailable in this Web Session flow");
+        if (typeof tool.server_label === "string") {
+          if (mcpLabels.has(tool.server_label)) blockers.push("MCP server labels must be unique");
+          mcpLabels.add(tool.server_label);
+        }
+        break;
+      case "tool_search":
+      case "programmatic_tool_calling":
+        blockers.push(`${String(tool.type)} is saved-only`);
+        break;
+      default:
+        blockers.push("the saved tool type is not executable");
+    }
+  }
+  if (functionCount > 64) blockers.push("at most 64 function tools can execute");
+  return [...new Set(blockers)];
+}
+
+export function knownSessionAdmissionBlocker(agent: SavedAgent): string | null {
+  const blockers = knownSessionAdmissionBlockers(agent);
+  return blockers.length ? `Current Core Session admission requires ${blockers.join(", ")}.` : null;
+}
diff --git a/apps/web/src/features/sessions/SessionsView.tsx b/apps/web/src/features/sessions/SessionsView.tsx
index 872246a..2969e90 100644
--- a/apps/web/src/features/sessions/SessionsView.tsx
+++ b/apps/web/src/features/sessions/SessionsView.tsx
@@ -31,6 +31,7 @@ import { Skeleton } from "../../components/Skeleton";
 import { StatusIcon, type StatusKind } from "../../components/StatusIcon";
 import type { CoreConnectionState } from "../../lib/connection";
 import { useThreadScroll } from "../../lib/use-thread-scroll";
+import { knownSessionAdmissionBlocker } from "../agents/session-admission";
 import {
   EnvironmentConnectionNotice,
   EnvironmentPanel,
@@ -299,9 +300,15 @@ export function SessionsView({
   onSend,
   onUpdateSession,
 }: SessionsViewProps) {
+  const firstStartableAgent = agents.find((agent) => !knownSessionAdmissionBlocker(agent));
+  const newSessionUnavailableReason = coreState === "ready" && !firstStartableAgent
+    ? agents.length
+      ? "No loaded Agent matches the known Core Session-admission profile."
+      : "Create or load a saved Agent before starting a Session."
+    : null;
   const [message, setMessage] = useState("");
   const [newSessionOpen, setNewSessionOpen] = useState(false);
-  const [agentId, setAgentId] = useState(agents[0]?.id ?? "");
+  const [agentId, setAgentId] = useState(firstStartableAgent?.id ?? "");
   const [actionSession, setActionSession] = useState<AgentSession | null>(null);
   const [viewport, setViewport] = useState<HTMLDivElement | null>(null);
   const [threadContent, setThreadContent] = useState<HTMLDivElement | null>(null);
@@ -320,9 +327,14 @@ export function SessionsView({
     threadContent,
   );
 
+  const selectedAgent = agents.find((agent) => agent.id === agentId);
+  const selectedAgentBlocker = selectedAgent ? knownSessionAdmissionBlocker(selectedAgent) : null;
+
   useEffect(() => {
-    if (!agentId && agents[0]) setAgentId(agents[0].id);
-  }, [agentId, agents]);
+    if (selectedAgent && !selectedAgentBlocker) return;
+    const next = agents.find((agent) => !knownSessionAdmissionBlocker(agent));
+    if ((next?.id ?? "") !== agentId) setAgentId(next?.id ?? "");
+  }, [agentId, agents, selectedAgent, selectedAgentBlocker]);
 
   useEffect(() => {
     if (!createRequest || createRequest === lastCreateRequestRef.current) return;
@@ -401,7 +413,7 @@ export function SessionsView({
   };
 
   const createSession = async () => {
-    if (coreState !== "ready" || !agentId) return;
+    if (coreState !== "ready" || !agentId || selectedAgentBlocker) return;
     try {
       await onCreateSession(agentId);
     } catch {
@@ -432,9 +444,27 @@ export function SessionsView({
             <button className="icon-button ghost" type="button" onClick={onRefresh} disabled={coreState === "connecting"} aria-label="Recover durable state">
               <RefreshCw className={coreState === "connecting" ? "refresh-spinning" : undefined} size={14} strokeWidth={1.5} />
             </button>
-            <button ref={newSessionActionRef} className="icon-button primary" type="button" onClick={() => setNewSessionOpen(true)} disabled={coreState !== "ready" || !agents.length} aria-label="New Session">
-              <Plus size={14} strokeWidth={1.5} />
-            </button>
+            <span className="action-tooltip">
+              <button
+                ref={newSessionActionRef}
+                className="icon-button primary session-create-trigger"
+                type="button"
+                onClick={() => {
+                  if (!newSessionUnavailableReason) setNewSessionOpen(true);
+                }}
+                disabled={coreState !== "ready"}
+                aria-disabled={newSessionUnavailableReason ? true : undefined}
+                aria-describedby={newSessionUnavailableReason ? "new-session-unavailable-reason" : undefined}
+                aria-label="New Session"
+              >
+                <Plus size={14} strokeWidth={1.5} />
+              </button>
+              {newSessionUnavailableReason ? (
+                <span className="action-tooltip-content" role="tooltip" id="new-session-unavailable-reason">
+                  {newSessionUnavailableReason}
+                </span>
+              ) : null}
+            </span>
           </div>
         </header>
 
@@ -710,7 +740,7 @@ export function SessionsView({
         footer={
           <>
             <button className="button outline" type="button" onClick={() => setNewSessionOpen(false)}>Cancel</button>
-            <button className="button primary" type="button" onClick={() => void createSession()} disabled={busy || coreState !== "ready" || !agentId}>
+            <button className="button primary" type="button" onClick={() => void createSession()} disabled={busy || coreState !== "ready" || !agentId || Boolean(selectedAgentBlocker)}>
               {busy ? "Creating…" : "Create Session"}
             </button>
           </>
@@ -719,12 +749,23 @@ export function SessionsView({
         <label className="field">
           <span>Saved Agent</span>
           <select value={agentId} onChange={(event) => setAgentId(event.target.value)}>
-            {agents.map((agent) => (
-              <option value={agent.id} key={agent.id}>{agent.name || agent.id} · {agent.model}</option>
-            ))}
+            {!firstStartableAgent ? <option value="">No Session-compatible saved Agent</option> : null}
+            {agents.map((agent) => {
+              const blocker = knownSessionAdmissionBlocker(agent);
+              return (
+                <option value={agent.id} key={agent.id} disabled={Boolean(blocker)}>
+                  {agent.name || agent.id} · {agent.model}{blocker ? " · Session unavailable" : ""}
+                </option>
+              );
+            })}
           </select>
-          <small>The initial slice uses environment: none; runtime placement remains core-owned.</small>
+          <small>The initial slice uses environment: none. Saved-only reasoning, non-auto tiers, JSON schema, multi-agent settings, unsupported tool shapes, and attached MCP credentials cannot start this Web Session flow.</small>
         </label>
+        {!firstStartableAgent ? (
+          <div className="notice warning" role="note">
+            No loaded Agent matches the known Core Session-admission profile. Create an Agent with the Web defaults or update the saved configuration first.
+          </div>
+        ) : null}
         <div className="notice success">
           <StatusIcon status="completed" /> The Session starts idle so the UI can subscribe before the first Turn.
         </div>
diff --git a/apps/web/src/style.css b/apps/web/src/style.css
index b450314..5580827 100644
--- a/apps/web/src/style.css
+++ b/apps/web/src/style.css
@@ -3745,8 +3745,8 @@ button.trace-step-row:hover {
   color: var(--fg-muted);
 }
 
-/* Product navigation and global creation keep OpenAI's clear information
-   architecture inside Parsar's existing Issue Ledger visual system. */
+/* Sidebar product navigation and global creation keep OpenAI's clear
+   information architecture inside Parsar's Issue Ledger visual system. */
 
 .product-header {
   position: relative;
@@ -3761,43 +3761,10 @@ button.trace-step-row:hover {
   border-bottom: 1px solid var(--line);
 }
 
-.product-navigation {
-  display: flex;
-  min-width: 0;
-  align-self: stretch;
-  align-items: flex-end;
-  gap: 22px;
-  overflow-x: auto;
-}
-
-.product-navigation button {
-  position: relative;
-  height: 38px;
-  flex: 0 0 auto;
-  padding: 0 1px;
-  color: var(--fg-muted);
-  font-size: 14px;
-  background: transparent;
-  border: 0;
-}
-
-.product-navigation button:hover,
-.product-navigation button.active {
-  color: var(--fg);
-}
-
-.product-navigation button.active::after {
-  position: absolute;
-  right: 0;
-  bottom: -1px;
-  left: 0;
-  height: 2px;
-  content: "";
-  background: var(--fg);
-  border-radius: 2px 2px 0 0;
+.product-navigation + .main-nav {
+  margin-top: 4px;
 }
 
-.product-navigation button:focus-visible,
 .create-menu [role="menuitem"]:focus-visible {
   outline: 2px solid color-mix(in srgb, var(--accent) 45%, transparent);
   outline-offset: 2px;
@@ -4047,6 +4014,16 @@ button.trace-step-row:hover {
   gap: 6px;
 }
 
+.agent-session-start[aria-disabled="true"] {
+  cursor: not-allowed;
+  opacity: 0.5;
+}
+
+.session-create-trigger[aria-disabled="true"] {
+  cursor: not-allowed;
+  opacity: 0.5;
+}
+
 .agent-created-notice {
   margin-bottom: 14px;
 }
@@ -4415,15 +4392,6 @@ button.trace-step-row:hover {
     gap: 8px;
   }
 
-  .product-navigation {
-    gap: 14px;
-  }
-
-  .product-navigation button {
-    height: 34px;
-    font-size: 12px;
-  }
-
   .create-menu {
     margin-bottom: 7px;
   }
diff --git a/docs/protocol-coverage.md b/docs/protocol-coverage.md
index 305841e..c4f357c 100644
--- a/docs/protocol-coverage.md
+++ b/docs/protocol-coverage.md
@@ -7,7 +7,7 @@ OpenAI-hosted service compatibility.
 
 - Parsar Core:
   [`0438880a`](https://github.com/MiniMax-AI-Dev/parsar/commit/0438880ab21aa16d05cb91a4c7f91cc0abc12358)
-- The product-navigation and Environment-unavailable boundaries were re-audited
+- The product-navigation, Agent execution-admission, and Environment-unavailable boundaries were re-audited
   against Parsar [`c15d42a2`](https://github.com/MiniMax-AI-Dev/parsar/commit/c15d42a270c0667bcaa83a6b9d01a9892ebf7edd).
   That revision still exposes only Environment retrieve plus Session-bound
   `self_hosted` creation; it adds no public Environment list, template, file, or
@@ -32,7 +32,7 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 
 | Resource / behavior | TypeScript client | Initial UI | Notes |
 | --- | --- | --- | --- |
-| Saved Agents create/list | Yes | Yes | Dedicated setup page covers model, name, instructions, metadata, read-only text-format projection, reasoning effort/summary, text verbosity, and service tier; saved settings do not prove runtime support |
+| Saved Agents create/list | Yes | Yes | Dedicated setup covers model, name, instructions, bounded metadata, and the Session-safe text/medium/implicit-reasoning/auto-tier profile; the broader Saved Agent contract is not execution proof |
 | Saved Agents retrieve/update/delete | Yes | Yes | Agent details support viewing, editing, and deleting saved Agents |
 | Sessions create/list/retrieve | Yes | Yes | UI creates idle `environment:none` Sessions; client types also cover the pinned `self_hosted` request and safe response projection |
 | Sessions update/delete | Yes | Yes | Title/string metadata editing and one-Session confirmed deletion; no bulk or Workspace deletion |
@@ -66,6 +66,20 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
   the sanitized Core base URL. Its authorization header always contains the literal
   `${AGENTS_CORE_API_KEY}` placeholder; it never reads or renders the connection's
   server-managed or current-tab bearer.
+- Saved Agent persistence and Session execution are separate contracts. Parsar
+  `c15d42a2` can store explicit reasoning, non-`auto` service tiers, and JSON-schema
+  text formats, but rejects each of them before creating a Session. Enabled
+  multi-agent configuration, saved-only tool types, deferred/invalid/duplicate
+  function or MCP identities, and MCP credentials without attached Vaults are
+  rejected at the same boundary. The Web never attaches Vaults in this flow, so it
+  treats a saved MCP `credential_id` as a deterministic blocker. The Web therefore
+  omits reasoning for new Agents, uses `service_tier:auto`, ordinary text, and
+  medium verbosity, and blocks every Session-start entry point for a loaded Agent
+  with a deterministic admission conflict. Existing saved-only values remain
+  inspectable; fields exposed for editing are never silently rewritten.
+- Saved Agent names are limited to 128 Unicode characters. Agent metadata is limited
+  to 16 string pairs, 64 Unicode characters per key, and 512 per value; the Web
+  enforces those limits before a write.
 - The Environments overview filters the currently loaded Session collection to exact
   `self_hosted` projections. A matching durable/live observation may annotate that
   row, but an absent row or observation remains unknown. The view does not derive a
@@ -143,7 +157,11 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 - `AGENTS_API_ENGINE` selects `codex` or an operator-enabled `claude_sdk` profile for
   new Sessions. The browser sends a model ID, not an executor selector.
 - Core has no standard model-catalog or capability-discovery route in this surface.
-  Web model presets are editable suggestions; the first real Turn is authoritative.
+  Web model presets are editable suggestions. Known reasoning, tier, format,
+  multi-agent, executable-tool-shape, and unattached-credential incompatibilities
+  are authoritative at Session creation; a real Turn remains necessary to prove
+  model/provider execution and conditional Codex `low`/`high` verbosity support.
+  Claude SDK accepts medium verbosity only.
 
 Environment creation and management beyond the narrow read, provider selection,
 Files, Plugins, Skills, Artifacts, Vault, hosted runtimes, and Workspace lifecycle

From 021353c648e464059b0b49c79cf3e56897cf92ba Mon Sep 17 00:00:00 2001
From: sam2tom <sam@sandbase.ai>
Date: Wed, 16 Sep 2026 22:16:48 +0800
Subject: [PATCH 3/3] fix(web): align chat with the current Core contract (#25)

Restore the documented Session events flow, require exact HTTP 204 admission, remove unsupported top-level Environment surfaces, and refresh the Parsar compatibility baseline.
---
 README.md                                     |  21 +-
 README.zh-CN.md                               |  16 +-
 apps/web/e2e/agents-lifecycle.spec.ts         |  33 +-
 apps/web/e2e/core-connection.spec.ts          |   8 +-
 apps/web/e2e/fixture-core.mjs                 |  16 +-
 apps/web/src/App.tsx                          |  11 -
 .../src/components/ConnectionModal.test.tsx   |  17 +-
 apps/web/src/components/ConnectionModal.tsx   |  10 +-
 apps/web/src/components/CreateMenu.test.tsx   |  11 +-
 apps/web/src/components/CreateMenu.tsx        |  10 -
 .../src/components/ProductNavigation.test.tsx |   6 +-
 apps/web/src/components/ProductNavigation.tsx |   5 +-
 .../features/CoreCollectionStates.test.tsx    |   9 +-
 .../environments/EnvironmentsView.test.tsx    | 112 -------
 .../environments/EnvironmentsView.tsx         | 171 -----------
 .../src/features/sessions/SessionsView.tsx    |  51 +++-
 .../sessions/environment/EnvironmentPanel.tsx |   2 +-
 apps/web/src/style.css                        | 286 ++----------------
 docs/architecture.md                          |  34 ++-
 docs/protocol-coverage.md                     |  77 ++---
 packages/agents-client/src/client.test.ts     |  32 ++
 packages/agents-client/src/client.ts          |  14 +-
 22 files changed, 267 insertions(+), 685 deletions(-)
 delete mode 100644 apps/web/src/features/environments/EnvironmentsView.test.tsx
 delete mode 100644 apps/web/src/features/environments/EnvironmentsView.tsx

diff --git a/README.md b/README.md
index ddaccce..898e97a 100644
--- a/README.md
+++ b/README.md
@@ -71,9 +71,12 @@ Restart `pnpm dev` after changing them. Keep credentials server-side. A direct
 Core URL in the connection dialog is only for a compatible Core that explicitly
 allows the Web origin, methods, and headers through CORS.
 
-Do not have a Core running yet? Follow [Connecting Agent Core](docs/core-connection.md).
-That guide contains the complete PostgreSQL, caller key, device, daemon, native
-harness, `CODEX_HOME`, security, verification, and shutdown procedures.
+Do not have a Core running yet? Use the immutable
+[current Parsar setup guide](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#standalone-http-service).
+The repository's [legacy Web connection runbook](docs/core-connection.md) is pinned
+to the older revision stated at its top; revalidate its PostgreSQL, caller-key,
+device, daemon, native-harness, `CODEX_HOME`, verification, and shutdown steps before
+applying them to a newer Core.
 
 ## First use
 
@@ -110,16 +113,18 @@ See [Architecture](docs/architecture.md) for the full component and trust bounda
 | --- | --- |
 | Web cannot reach Core | Confirm the Core address and `AGENTS_API_PROXY_TARGET`, then restart Vite |
 | `401 invalid_api_key` | The plaintext caller bearer must match the current Core key binding |
-| `503 execution_unavailable` / `Execution is not enabled` | Core is reachable but has no enabled execution path; connect its configured executor/daemon |
+| `503 execution_unavailable` / `Execution is not enabled` | Core rejected execution; inspect its safe error plus runtime and ownership state. A worker, executor, or daemon may be unconfigured or disconnected, or an execution lease may have been lost |
 | Agent saves but its model fails | Use a model ID and provider credential supported by the connected runtime |
 
-`/healthz` proves HTTP liveness only, not chat readiness. See the
-[full troubleshooting guide](docs/core-connection.md#troubleshooting) before retrying
-an uncertain request.
+`/healthz` proves HTTP liveness only, not chat readiness. Check durable Core state and
+the current pinned Parsar guide before retrying an uncertain request; the
+[legacy 043 troubleshooting snapshot](docs/core-connection.md#troubleshooting) is
+historical context only.
 
 ## Documentation
 
-- [Connect Agent Core](docs/core-connection.md) — full local and deployment setup
+- [Current Parsar Core setup](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#standalone-http-service) — immutable current upstream guide
+- [Legacy Web connection runbook](docs/core-connection.md) — historical `0438880` snapshot; revalidate before use
 - [Protocol coverage](docs/protocol-coverage.md) — exact supported API surface
 - [Architecture](docs/architecture.md) — ownership, runtime, and trust boundaries
 - [Roadmap](docs/roadmap.md) — planned Web and Core integrations
diff --git a/README.zh-CN.md b/README.zh-CN.md
index a186461..badac83 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -70,9 +70,11 @@ AGENTS_API_PROXY_TOKEN_FILE=/absolute/private/path/to/web-token
 修改后重启 `pnpm dev`。凭据应保留在服务端。只有兼容 Core 通过 CORS
 明确允许 Web 的源、方法和请求头时，才能在连接对话框中使用 Core 直连 URL。
 
-还没有运行中的 Core？请参阅[连接 Agent Core](docs/core-connection.md)。
-该文档包含完整的 PostgreSQL、调用方凭据、执行设备、daemon、原生执行适配层（harness）、
-`CODEX_HOME`、安全、验证和停止流程。
+还没有运行中的 Core？请使用不可变的
+[当前 Parsar 配置指南](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#standalone-http-service)。
+仓库内的[旧版 Web 连接手册](docs/core-connection.md)固定在文首标注的旧 revision；
+将其中 PostgreSQL、调用方凭据、执行设备、daemon、原生执行适配层（harness）、
+`CODEX_HOME`、验证和停止流程用于更新版 Core 前必须重新核对。
 
 ## 第一次使用
 
@@ -108,15 +110,17 @@ WebSocket 当作 API URL。
 | --- | --- |
 | Web 无法访问 Core | 确认 Core 地址和 `AGENTS_API_PROXY_TARGET`，然后重启 Vite |
 | `401 invalid_api_key` | 明文调用方 Bearer 凭据必须与 Core 当前的密钥绑定匹配 |
-| `503 execution_unavailable` / `Execution is not enabled` | Core 可以访问，但没有已启用的执行链路；请连接其配置的 executor/daemon |
+| `503 execution_unavailable` / `Execution is not enabled` | Core 拒绝执行；请检查其安全错误、运行时和 ownership 状态。worker、executor 或 daemon 可能未配置或已断连，也可能丢失了执行 lease |
 | Agent 保存成功但模型运行失败 | 使用已连接运行时支持的 model ID 和提供商凭据 |
 
 `/healthz` 只能证明 HTTP 存活，不能证明聊天已就绪。重试结果不确定的请求前，
-请先查看[完整故障排查](docs/core-connection.md#troubleshooting)。
+请先核对 Core 持久状态和当前固定版本的 Parsar 指南；
+[旧版 043 故障排查快照](docs/core-connection.md#troubleshooting)仅供历史参考。
 
 ## 文档入口
 
-- [连接 Agent Core](docs/core-connection.md) — 完整本地和部署配置
+- [当前 Parsar Core 配置](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#standalone-http-service) — 不可变的当前上游指南
+- [旧版 Web 连接手册](docs/core-connection.md) — 历史 `0438880` 快照，使用前必须重新核对
 - [协议覆盖范围](docs/protocol-coverage.md) — 准确的已支持 API 范围
 - [架构说明](docs/architecture.md) — 所有权、运行时和信任边界
 - [路线图](docs/roadmap.md) — 计划中的 Web 和 Core 集成
diff --git a/apps/web/e2e/agents-lifecycle.spec.ts b/apps/web/e2e/agents-lifecycle.spec.ts
index a157cc0..29ac6c2 100644
--- a/apps/web/e2e/agents-lifecycle.spec.ts
+++ b/apps/web/e2e/agents-lifecycle.spec.ts
@@ -503,8 +503,7 @@ test("keeps the Agent ledger and dialogs usable at 390 px in light and dark mode
   expect(metrics.ledger?.right).toBeLessThanOrEqual(390);
   await attachScreenshot(page, testInfo, "narrow-light-agent-ledger");
 
-  await page.getByRole("button", { name: "Environments", exact: true }).click();
-  await expect(page.getByRole("heading", { name: "Environments Observed" })).toBeVisible();
+  await expect(page.getByRole("button", { name: "Environments", exact: true })).toHaveCount(0);
   const sessionsNavigation = page.getByRole("button", { name: "Sessions", exact: true });
   await sessionsNavigation.click();
   await expect(sessionsNavigation).toHaveAttribute("aria-current", "page");
@@ -515,6 +514,9 @@ test("keeps the Agent ledger and dialogs usable at 390 px in light and dark mode
   await globalCreate.click();
   const createPanel = page.getByRole("menu", { name: "Create" });
   await expect(createPanel).toBeVisible();
+  await expect(createPanel.getByRole("menuitem")).toHaveCount(2);
+  await expect(createPanel.getByRole("menuitem", { name: /Environment template/i })).toHaveCount(0);
+  await expect(createPanel.getByRole("menuitem", { name: /Environment key/i })).toHaveCount(0);
   const createPanelBox = await createPanel.boundingBox();
   expect(createPanelBox).not.toBeNull();
   expect(createPanelBox?.x ?? -1).toBeGreaterThanOrEqual(0);
@@ -1043,7 +1045,10 @@ test("renders self-hosted Environment and Workspace state safely across reconnec
   await expect(panel.getByRole("link", { name: "Launcher setup" })).toBeVisible();
   await expect(page.getByRole("region", { name: "Environment connection required" })).toBeVisible();
   await expect(page.getByRole("region", { name: "Function result required" })).toBeVisible();
-  await expect(page.getByLabel("Function result or error")).toBeVisible();
+  await expect(page.getByLabel("Function result or error")).toBeEnabled();
+  await expect(page.getByRole("button", { name: "Return error" })).toBeEnabled();
+  await expect(page.getByRole("button", { name: "Submit result" })).toBeDisabled();
+  await expect(page.getByRole("button", { name: "Cancel active Turn" })).toBeEnabled();
   await expect(page.locator("body")).not.toContainText("launcher:private");
   await expect(page.locator("body")).not.toContainText("executor_token=secret");
   await expect(page.locator('a[href^="file:"]')).toHaveCount(0);
@@ -1404,3 +1409,25 @@ test("manually retries uncertain sends with the original key only while the payl
   expect(sends[5]?.idempotencyKey).not.toBe(sends[4]?.idempotencyKey);
   await attachScreenshot(page, testInfo, "desktop-send-recovery");
 });
+
+test("keeps cancellation available for an Environment-only required action", async ({ page, request }) => {
+  await resetFixture(request);
+  await controlFixture(request, { environmentScenario: 6 });
+  await page.goto("/");
+  await expect(page.getByText("listening", { exact: true })).toBeVisible();
+  await expect(page.getByRole("region", { name: "Environment connection required" })).toBeVisible();
+  await expect(page.getByRole("region", { name: "Function result required" })).toHaveCount(0);
+  const writesBefore = (await fixtureRequests(request)).filter(
+    (entry) => entry.method === "POST" && entry.path.endsWith("/events"),
+  ).length;
+  const cancel = page.getByRole("button", { name: "Cancel active Turn" });
+  await expect(cancel).toBeEnabled();
+  await cancel.click();
+  await expect.poll(async () => (await fixtureRequests(request)).filter(
+    (entry) => entry.method === "POST" && entry.path.endsWith("/events"),
+  ).length).toBe(writesBefore + 1);
+  const writes = (await fixtureRequests(request)).filter(
+    (entry) => entry.method === "POST" && entry.path.endsWith("/events"),
+  );
+  expect(writes.at(-1)?.body).toEqual({ events: [{ type: "agent.session.input.cancel" }] });
+});
diff --git a/apps/web/e2e/core-connection.spec.ts b/apps/web/e2e/core-connection.spec.ts
index c7b86c4..e357bcd 100644
--- a/apps/web/e2e/core-connection.spec.ts
+++ b/apps/web/e2e/core-connection.spec.ts
@@ -303,7 +303,7 @@ test("announces loading, authenticated access, and each safe failure state from
     methods.push(route.request().method());
     const reply = replies.shift();
     if (!reply) return route.abort("failed");
-    await new Promise((resolve) => setTimeout(resolve, 50));
+    await new Promise((resolve) => setTimeout(resolve, 150));
     if ("abort" in reply) return route.abort("failed");
     return route.fulfill({
       status: reply.status,
@@ -333,7 +333,8 @@ test("announces loading, authenticated access, and each safe failure state from
     await expect(loading).toContainText("Testing Core connection…");
     const terminal = dialog.getByRole(expected.role);
     await expect(terminal).toContainText(expected.text);
-    await expect(terminal).toContainText("Execution readiness: Unknown / not verified");
+    await expect(terminal).toContainText("Chat uses the current Agents API contract");
+    await expect(terminal).toContainText("does not start a Turn or verify its runtime dependencies");
     if (expected.absentText) await expect(terminal).not.toContainText(expected.absentText);
   }
 
@@ -373,7 +374,8 @@ test("turns a stalled probe into one bounded unreachable result", async ({ page,
     (window as ProbeInstrumentationWindow).__stalledProbeCallCount ?? 0
   ))).toBe(1);
   await expect(dialog.getByRole("alert")).toContainText("Core unreachable", { timeout: 7_500 });
-  await expect(dialog.getByRole("alert")).toContainText("Execution readiness: Unknown / not verified");
+  await expect(dialog.getByRole("alert")).toContainText("Chat uses the current Agents API contract");
+  await expect(dialog.getByRole("alert")).toContainText("does not start a Turn or verify its runtime dependencies");
   expect(await page.evaluate(() => (window as ProbeInstrumentationWindow).__stalledProbeCallCount)).toBe(1);
 });
 
diff --git a/apps/web/e2e/fixture-core.mjs b/apps/web/e2e/fixture-core.mjs
index e6dfee1..577736b 100644
--- a/apps/web/e2e/fixture-core.mjs
+++ b/apps/web/e2e/fixture-core.mjs
@@ -253,7 +253,7 @@ function applyEnvironmentScenario(value) {
   const session = state.sessions[0];
   if (!session) return;
   const hostileRemote = "https://launcher:private@executor.example.test/connect?executor_token=secret#credential";
-  if (value === 1 || value === 4 || value === 5) {
+  if (value === 1 || value === 4 || value === 5 || value === 6) {
     session.environment = {
       type: "self_hosted",
       id: value === 5 ? canonicalEnvironmentUuid.toUpperCase() : "environment_fixture",
@@ -261,11 +261,15 @@ function applyEnvironmentScenario(value) {
       workspace_directory: `/workspace/<script>safe</script>/${"long/".repeat(45)}project`,
       capability_directories: ["/capabilities/read-only", `/capabilities/${"wide/".repeat(55)}`],
     };
-    session.status = value === 1 ? "requires_action" : "idle";
-    session.required_actions = value === 1 ? [
-      { type: "environment_connection", environment_id: "environment_fixture" },
-      { type: "function_call", call_id: "call_fixture", turn_id: "turn_fixture", name: "confirm", arguments: { safe: true } },
-    ] : [];
+    session.status = value === 1 || value === 6 ? "requires_action" : "idle";
+    session.required_actions = value === 1
+      ? [
+          { type: "environment_connection", environment_id: "environment_fixture" },
+          { type: "function_call", call_id: "call_fixture", turn_id: "turn_fixture", name: "confirm", arguments: { safe: true } },
+        ]
+      : value === 6
+        ? [{ type: "environment_connection", environment_id: "environment_fixture" }]
+        : [];
     return;
   }
   if (value === 2) {
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index bccdca3..c9fb58e 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -29,7 +29,6 @@ import {
   requestAgentDetail,
   requestAgentUpdate,
 } from "./features/agents/agent-actions";
-import { EnvironmentsView } from "./features/environments/EnvironmentsView";
 import {
   SessionsView,
   type SessionDetailState,
@@ -1264,16 +1263,6 @@ export function App() {
               onUpdate={updateAgent}
             />
           ) : null}
-          {view === "environments" ? (
-            <EnvironmentsView
-              sessions={sessions}
-              observations={environmentObservations}
-              onOpenSession={(sessionId) => {
-                setSelectedId(sessionId);
-                setView("sessions");
-              }}
-            />
-          ) : null}
           {view === "system" ? <SystemView /> : null}
         </div>
       </main>
diff --git a/apps/web/src/components/ConnectionModal.test.tsx b/apps/web/src/components/ConnectionModal.test.tsx
index b4536fd..7c07ea6 100644
--- a/apps/web/src/components/ConnectionModal.test.tsx
+++ b/apps/web/src/components/ConnectionModal.test.tsx
@@ -89,11 +89,12 @@ describe("Agent Core connection modes", () => {
     const markup = renderModal("/v1", true);
 
     expect(markup).toContain("Operator-owned setup");
-    expect(markup).toContain("Connection guide");
-    expect(markup).toContain("Troubleshooting");
+    expect(markup).toContain("Legacy Web guide · 043 snapshot");
+    expect(markup).toContain("Legacy troubleshooting · 043 snapshot");
     expect(markup).toContain("Parsar Core setup");
     expect(markup).toContain("98c5b3312ad33e1fae8b94283a011eb3e5f4ee2c");
-    expect(markup).toContain("0438880ab21aa16d05cb91a4c7f91cc0abc12358");
+    expect(markup).toContain("d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee");
+    expect(markup).not.toContain("0438880ab21aa16d05cb91a4c7f91cc0abc12358");
     expect(markup).not.toContain("f7cdf591396529880d80f8211fc7a0f4768fdf46");
     expect(markup).not.toContain("8cc2898ca42b272cb3771234ee6a0ad0d2e932ba");
     expect(markup).not.toContain("7409e00ca25311805a9f8f0d03614f820e407642");
@@ -104,14 +105,14 @@ describe("Agent Core connection modes", () => {
     expect(markup).not.toContain("AGENTS_API_DAEMON_WS_URL");
   });
 
-  it("states the GET-only probe boundary and unknown execution readiness", () => {
+  it("states the GET-only probe boundary without disabling the current chat contract", () => {
     const markup = renderModal("/v1", true);
 
     expect(markup).toContain("Test connection");
     expect(markup).toContain("with one GET");
     expect(markup).toContain("never creates an Agent, Session, Turn, or Item");
-    expect(markup).toContain("Execution readiness remains Unknown / not verified");
-    expect(markup).toContain("does not prove a daemon, model, or provider is ready");
+    expect(markup).toContain("Chat uses the current Core events contract");
+    expect(markup).toContain("a real request can still fail");
   });
 });
 
@@ -172,8 +173,8 @@ describe("Connection probe status", () => {
     const markup = renderToStaticMarkup(<ConnectionProbeStatus state={state} />);
 
     expect(markup).toContain(expected);
-    expect(markup).toContain("Execution readiness: Unknown / not verified");
-    expect(markup).not.toContain("Execution readiness: Ready");
+    expect(markup).toContain("Chat uses the current Agents API contract");
+    expect(markup).toContain("does not start a Turn or verify its runtime dependencies");
   });
 
   it("uses an alert for failures and a polite status for authenticated access", () => {
diff --git a/apps/web/src/components/ConnectionModal.tsx b/apps/web/src/components/ConnectionModal.tsx
index 63ccc76..a63ac08 100644
--- a/apps/web/src/components/ConnectionModal.tsx
+++ b/apps/web/src/components/ConnectionModal.tsx
@@ -29,7 +29,7 @@ export type ConnectionProbeState =
   | { status: "complete"; result: CoreProbeResult };
 
 const webBaseline = "98c5b3312ad33e1fae8b94283a011eb3e5f4ee2c";
-const parsarBaseline = "0438880ab21aa16d05cb91a4c7f91cc0abc12358";
+const parsarBaseline = "d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee";
 const operatorGuideUrl = `https://github.com/MiniMax-AI-Dev/agents-core-web/blob/${webBaseline}/docs/core-connection.md`;
 const troubleshootingUrl = `${operatorGuideUrl}#troubleshooting`;
 const parsarCoreSetupUrl = `https://github.com/MiniMax-AI-Dev/parsar/blob/${parsarBaseline}/services/agents-api/README.md#standalone-http-service`;
@@ -102,7 +102,7 @@ export function ConnectionProbeStatus({ state }: { state: ConnectionProbeState }
     >
       <strong>{copy.title}</strong>
       <p>{copy.detail}</p>
-      <small>Execution readiness: Unknown / not verified.</small>
+      <small>Chat uses the current Agents API contract. This read-only probe does not start a Turn or verify its runtime dependencies.</small>
     </div>
   );
 }
@@ -316,11 +316,11 @@ export function ConnectionModal({
         </div>
         <div className="connection-guide-links">
           <a className="connection-guide-link" href={operatorGuideUrl} target="_blank" rel="noreferrer">
-            Connection guide
+            Legacy Web guide · 043 snapshot
             <ExternalLink size={12} strokeWidth={1.5} aria-hidden="true" />
           </a>
           <a className="connection-guide-link" href={troubleshootingUrl} target="_blank" rel="noreferrer">
-            Troubleshooting
+            Legacy troubleshooting · 043 snapshot
             <ExternalLink size={12} strokeWidth={1.5} aria-hidden="true" />
           </a>
           <a className="connection-guide-link" href={parsarCoreSetupUrl} target="_blank" rel="noreferrer">
@@ -331,7 +331,7 @@ export function ConnectionModal({
       </section>
       <div className="notice neutral">
         <Info size={14} strokeWidth={1.5} aria-hidden="true" />
-        Execution readiness remains Unknown / not verified. HTTP access does not prove a daemon, model, or provider is ready.
+        Test connection verifies Agents API access only. Chat uses the current Core events contract; a real request can still fail when its worker, executor, model, or provider is unavailable.
       </div>
     </Modal>
   );
diff --git a/apps/web/src/components/CreateMenu.test.tsx b/apps/web/src/components/CreateMenu.test.tsx
index 1c3d411..13b7c0b 100644
--- a/apps/web/src/components/CreateMenu.test.tsx
+++ b/apps/web/src/components/CreateMenu.test.tsx
@@ -4,7 +4,7 @@ import { describe, expect, it } from "vitest";
 import { CreateMenuContent } from "./CreateMenu";
 
 describe("Create menu", () => {
-  it("keeps supported actions separate from explicit Core-unavailable resources", () => {
+  it("shows only actions supported by the current Core contract", () => {
     const html = renderToStaticMarkup(
       <CreateMenuContent
         canCreateAgent
@@ -15,10 +15,11 @@ describe("Create menu", () => {
     );
 
     expect(html).toContain('role="menu"');
-    expect(html).toContain("Environment template");
-    expect(html).toContain("Core exposes no template API");
-    expect(html).toContain("operator-owned, never browser-managed");
-    expect(html.match(/aria-disabled="true"/g)).toHaveLength(2);
+    expect(html).toContain("Agent");
+    expect(html).toContain("Start Session");
+    expect(html).not.toContain("Environment template");
+    expect(html).not.toContain("Environment key");
+    expect(html).not.toContain('aria-disabled="true"');
     expect(html).not.toContain("executor_token");
   });
 });
diff --git a/apps/web/src/components/CreateMenu.tsx b/apps/web/src/components/CreateMenu.tsx
index 738f84e..ee67745 100644
--- a/apps/web/src/components/CreateMenu.tsx
+++ b/apps/web/src/components/CreateMenu.tsx
@@ -1,8 +1,6 @@
 import {
   Bot,
   ChevronDown,
-  FileBox,
-  KeyRound,
   MessageSquare,
   Plus,
 } from "lucide-react";
@@ -27,14 +25,6 @@ export function CreateMenuContent({
         <Bot size={16} strokeWidth={1.5} aria-hidden="true" />
         <span><strong>Agent</strong><small>Save a reusable Agent definition</small></span>
       </button>
-      <div className="create-menu-unavailable" role="menuitem" aria-disabled="true">
-        <FileBox size={16} strokeWidth={1.5} aria-hidden="true" />
-        <span><strong>Environment template</strong><small>Unavailable · Core exposes no template API</small></span>
-      </div>
-      <div className="create-menu-unavailable" role="menuitem" aria-disabled="true">
-        <KeyRound size={16} strokeWidth={1.5} aria-hidden="true" />
-        <span><strong>Environment key</strong><small>Unavailable · operator-owned, never browser-managed</small></span>
-      </div>
       <button type="button" role="menuitem" onClick={onStartSession} disabled={!canStartSession}>
         <MessageSquare size={16} strokeWidth={1.5} aria-hidden="true" />
         <span>
diff --git a/apps/web/src/components/ProductNavigation.test.tsx b/apps/web/src/components/ProductNavigation.test.tsx
index e5304b2..c87c068 100644
--- a/apps/web/src/components/ProductNavigation.test.tsx
+++ b/apps/web/src/components/ProductNavigation.test.tsx
@@ -4,17 +4,17 @@ import { describe, expect, it } from "vitest";
 import { ProductNavigation } from "./ProductNavigation";
 
 describe("Product navigation", () => {
-  it("exposes the three product destinations and current page", () => {
+  it("exposes only the Core-backed product destinations and current page", () => {
     const html = renderToStaticMarkup(
-      <ProductNavigation active="environments" onSelect={() => undefined} />,
+      <ProductNavigation active="sessions" onSelect={() => undefined} />,
     );
 
     expect(html).toContain('aria-label="Agents product"');
     expect(html).toContain('class="main-nav product-navigation"');
     expect(html).toContain("Workspace");
     expect(html).toContain("Agents");
-    expect(html).toContain("Environments");
     expect(html).toContain("Sessions");
+    expect(html).not.toContain("Environments");
     expect(html).toContain('aria-current="page"');
   });
 });
diff --git a/apps/web/src/components/ProductNavigation.tsx b/apps/web/src/components/ProductNavigation.tsx
index 2b8cba7..c623497 100644
--- a/apps/web/src/components/ProductNavigation.tsx
+++ b/apps/web/src/components/ProductNavigation.tsx
@@ -1,10 +1,9 @@
-import { Bot, Boxes, MessageSquare, type LucideIcon } from "lucide-react";
+import { Bot, MessageSquare, type LucideIcon } from "lucide-react";
 
-export type ProductView = "agents" | "environments" | "sessions";
+export type ProductView = "agents" | "sessions";
 
 const productViews: Array<{ id: ProductView; label: string; icon: LucideIcon }> = [
   { id: "agents", label: "Agents", icon: Bot },
-  { id: "environments", label: "Environments", icon: Boxes },
   { id: "sessions", label: "Sessions", icon: MessageSquare },
 ];
 
diff --git a/apps/web/src/features/CoreCollectionStates.test.tsx b/apps/web/src/features/CoreCollectionStates.test.tsx
index 047615a..37b98ed 100644
--- a/apps/web/src/features/CoreCollectionStates.test.tsx
+++ b/apps/web/src/features/CoreCollectionStates.test.tsx
@@ -303,11 +303,13 @@ describe("Agent Core collection states", () => {
       />,
     );
 
-    expect(failed).toContain("Execution daemon is unavailable");
+    expect(failed).toContain("Core execution is unavailable");
     expect(failed).toContain("Execution is not enabled on this service.");
     expect(failed).toContain("Your draft was restored and was not retried.");
-    expect(failed).toContain("AGENTS_API_DAEMON_WS_URL");
-    expect(failed).toContain("Executor setup");
+    expect(failed).toContain("operator runtime configuration");
+    expect(failed).toContain("Core runtime setup");
+    expect(failed).toContain("d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee");
+    expect(failed).not.toContain("AGENTS_API_DAEMON_WS_URL");
   });
 
   it("renders Environment connection actions separately from simultaneous function results", () => {
@@ -392,6 +394,7 @@ describe("Agent Core collection states", () => {
       expect(html).toContain("will not infer a form or continue the Session");
       expect(html).not.toContain('aria-label="Message the Agent"');
       expect(html).not.toContain('aria-label="Function result or error"');
+      expect(html).toContain('aria-label="Cancel active Turn"');
       expect(html).not.toContain("must-not-render");
     }
   });
diff --git a/apps/web/src/features/environments/EnvironmentsView.test.tsx b/apps/web/src/features/environments/EnvironmentsView.test.tsx
deleted file mode 100644
index 09a7c50..0000000
--- a/apps/web/src/features/environments/EnvironmentsView.test.tsx
+++ /dev/null
@@ -1,112 +0,0 @@
-import { renderToStaticMarkup } from "react-dom/server";
-import { describe, expect, it } from "vitest";
-
-import type { AgentSession } from "@agents-core-web/agents-client";
-
-import type { ScopedEnvironmentObservation } from "../sessions/environment/environment-state";
-import { EnvironmentsView, observedEnvironments } from "./EnvironmentsView";
-
-const selfHosted: AgentSession = {
-  id: "session-1",
-  object: "agent.session",
-  agent: {
-    id: "agent-1",
-    model: "provider/model",
-    name: "Builder",
-    instructions: null,
-    multi_agent: { enabled: false, max_concurrent_subagents: null },
-    reasoning: {},
-    service_tier: "auto",
-    text: { format: { type: "text" }, verbosity: "medium" },
-    tools: [],
-  },
-  environment: {
-    type: "self_hosted",
-    id: "environment-1",
-    remote_url: "https://executor.example/connect?private=hidden",
-    workspace_directory: "/workspace/project",
-    capability_directories: [],
-  },
-  status: "idle",
-  error: null,
-  metadata: {},
-  required_actions: [],
-  vault_ids: [],
-  usage: null,
-  created_at: 1,
-  last_active_at: 1,
-};
-
-const expiredObservation: ScopedEnvironmentObservation = {
-  sessionId: selfHosted.id,
-  streamEpoch: 1,
-  observation: {
-    source: "durable",
-    environmentId: "environment-1",
-    environmentType: "self_hosted",
-    status: "expired",
-    resource: {
-      id: "environment-1",
-      object: "agent.environment",
-      type: "self_hosted",
-      status: "expired",
-      files: [],
-      plugins: [],
-      skills: [],
-    },
-  },
-};
-
-describe("Environments overview", () => {
-  it("derives only self-hosted projections and keeps the matching observation", () => {
-    const none = { ...selfHosted, id: "session-none", environment: { type: "none" as const } };
-    const observed = observedEnvironments(
-      [none, selfHosted],
-      new Map([[selfHosted.id, expiredObservation]]),
-    );
-
-    expect(observed).toHaveLength(1);
-    expect(observed[0]?.environment.id).toBe("environment-1");
-    expect(observed[0]?.observation?.status).toBe("expired");
-  });
-
-  it("ignores malformed and future Environment projections instead of crashing", () => {
-    const malformed = {
-      ...selfHosted,
-      id: "session-malformed",
-      environment: null,
-    } as unknown as AgentSession;
-    const future = {
-      ...selfHosted,
-      id: "session-future",
-      environment: { type: "future_hosted", id: "environment-future" },
-    } as unknown as AgentSession;
-
-    expect(observedEnvironments([malformed, future], new Map())).toEqual([]);
-    expect(() => renderToStaticMarkup(
-      <EnvironmentsView
-        sessions={[malformed, future]}
-        observations={new Map()}
-        onOpenSession={() => undefined}
-      />,
-    )).not.toThrow();
-  });
-
-  it("renders explicit catalog, template, key, and readiness boundaries", () => {
-    const html = renderToStaticMarkup(
-      <EnvironmentsView
-        sessions={[selfHosted]}
-        observations={new Map([[selfHosted.id, expiredObservation]])}
-        onOpenSession={() => undefined}
-      />,
-    );
-
-    expect(html).toContain("Not an exhaustive Environment catalog");
-    expect(html).toContain("Environment templates");
-    expect(html).toContain("Environment keys");
-    expect(html).toContain("No secret is created, stored, or displayed here");
-    expect(html).toContain("Environment expired");
-    expect(html).toContain("does not prove executor, runtime, model, or provider readiness");
-    expect(html).not.toContain("private=hidden");
-  });
-});
diff --git a/apps/web/src/features/environments/EnvironmentsView.tsx b/apps/web/src/features/environments/EnvironmentsView.tsx
deleted file mode 100644
index 523e636..0000000
--- a/apps/web/src/features/environments/EnvironmentsView.tsx
+++ /dev/null
@@ -1,171 +0,0 @@
-import { AlertCircle, Eye, FileBox, KeyRound, Search } from "lucide-react";
-import { useState } from "react";
-
-import type {
-  AgentSession,
-  EnvironmentConnectionAction,
-  SelfHostedAgentEnvironment,
-} from "@agents-core-web/agents-client";
-
-import { EnvironmentPanel } from "../sessions/environment/EnvironmentPanel";
-import {
-  environmentIdsMatch,
-  type EnvironmentObservation,
-  type ScopedEnvironmentObservation,
-} from "../sessions/environment/environment-state";
-
-export interface ObservedEnvironment {
-  environment: SelfHostedAgentEnvironment;
-  observation: EnvironmentObservation | null;
-  session: AgentSession;
-}
-
-function isSelfHostedEnvironment(environment: unknown): environment is SelfHostedAgentEnvironment {
-  if (environment === null || typeof environment !== "object" || Array.isArray(environment)) return false;
-  const value = environment as Record<string, unknown>;
-  return value.type === "self_hosted" &&
-    typeof value.id === "string" &&
-    typeof value.remote_url === "string" &&
-    typeof value.workspace_directory === "string" &&
-    Array.isArray(value.capability_directories) &&
-    value.capability_directories.every((entry) => typeof entry === "string");
-}
-
-function connectionActions(session: AgentSession): EnvironmentConnectionAction[] {
-  const actions: unknown = session.required_actions;
-  if (!Array.isArray(actions)) return [];
-  return actions.filter((action): action is EnvironmentConnectionAction => (
-    action !== null &&
-    typeof action === "object" &&
-    (action as Record<string, unknown>).type === "environment_connection" &&
-    typeof (action as Record<string, unknown>).environment_id === "string"
-  ));
-}
-
-export function observedEnvironments(
-  sessions: AgentSession[],
-  observations: ReadonlyMap<string, ScopedEnvironmentObservation>,
-): ObservedEnvironment[] {
-  return sessions.flatMap((session) => {
-    const environment: unknown = session.environment;
-    if (!isSelfHostedEnvironment(environment)) return [];
-    const scoped = observations.get(session.id);
-    const observation = scoped?.sessionId === session.id &&
-      environmentIdsMatch(scoped.observation.environmentId, environment.id)
-      ? scoped.observation
-      : null;
-    return [{ environment, observation, session }];
-  });
-}
-
-export function EnvironmentsView({
-  observations,
-  onOpenSession,
-  sessions,
-}: {
-  observations: ReadonlyMap<string, ScopedEnvironmentObservation>;
-  onOpenSession: (sessionId: string) => void;
-  sessions: AgentSession[];
-}) {
-  const [query, setQuery] = useState("");
-  const allObserved = observedEnvironments(sessions, observations);
-  const normalizedQuery = query.trim().toLowerCase();
-  const visible = normalizedQuery ? allObserved.filter(({ environment, session }) => [
-    environment.id,
-    environment.workspace_directory,
-    environment.remote_url,
-    session.id,
-    session.agent.name,
-  ].some((value) => value?.toLowerCase().includes(normalizedQuery))) : allObserved;
-
-  return (
-    <section className="page-section environments-page">
-      <header className="page-header environments-header">
-        <div>
-          <h1>Environments <span>Observed</span></h1>
-          <p>Session-scoped self-hosted projections from the currently loaded Core data.</p>
-        </div>
-        <label className="search-control">
-          <Search size={14} strokeWidth={1.5} aria-hidden="true" />
-          <input
-            type="search"
-            value={query}
-            onChange={(event) => setQuery(event.target.value)}
-            placeholder="Search Environment, Session, or path…"
-            aria-label="Search observed Environments"
-          />
-        </label>
-      </header>
-
-      <div className="environments-scroll">
-        <section className="environment-catalog-boundary" role="note" aria-label="Environment catalog boundary">
-          <AlertCircle size={16} strokeWidth={1.5} aria-hidden="true" />
-          <div>
-            <strong>Not an exhaustive Environment catalog</strong>
-            <p>
-              Agent Core exposes retrieval by ID, not list. This view derives only from {sessions.length} currently loaded Session{sessions.length === 1 ? "" : "s"}; absent Environments remain unknown.
-            </p>
-          </div>
-        </section>
-
-        <section className="environment-unavailable-grid" aria-label="Unavailable Environment APIs">
-          <article>
-            <FileBox size={17} strokeWidth={1.5} aria-hidden="true" />
-            <div><strong>Environment templates</strong><span>Unavailable</span></div>
-            <p>The connected Core contract has no template create, list, retrieve, update, or delete API.</p>
-          </article>
-          <article>
-            <KeyRound size={17} strokeWidth={1.5} aria-hidden="true" />
-            <div><strong>Environment keys</strong><span>Operator-owned</span></div>
-            <p>Executor credentials are issued outside the browser. No secret is created, stored, or displayed here.</p>
-          </article>
-        </section>
-
-        <section className="observed-environments" aria-labelledby="observed-environments-title">
-          <header>
-            <div>
-              <h2 id="observed-environments-title">Observed self-hosted Environments</h2>
-              <p>Durable Session projection plus the latest matching Environment observation already read by this Web.</p>
-            </div>
-            <span>{visible.length}{normalizedQuery ? ` of ${allObserved.length}` : ""}</span>
-          </header>
-
-          {visible.length ? (
-            <div className="observed-environment-list">
-              {visible.map(({ environment, observation, session }) => (
-                <article className="observed-environment" key={`${session.id}:${environment.id}`}>
-                  <header>
-                    <div>
-                      <strong>{session.agent.name || "Untitled Agent"}</strong>
-                      <span>Session <code>{session.id}</code></span>
-                    </div>
-                    <button className="button outline" type="button" onClick={() => onOpenSession(session.id)}>
-                      <Eye size={13} strokeWidth={1.5} aria-hidden="true" />
-                      Open Session
-                    </button>
-                  </header>
-                  <EnvironmentPanel
-                    environment={environment}
-                    observation={observation}
-                    connectionActions={connectionActions(session)}
-                  />
-                </article>
-              ))}
-            </div>
-          ) : (
-            <div className="environment-overview-empty">
-              <Eye size={22} strokeWidth={1.5} aria-hidden="true" />
-              <h3>{allObserved.length ? "No matching observed Environments" : "No self-hosted Environment is currently observed"}</h3>
-              <p>
-                {allObserved.length
-                  ? "Try another Environment ID, Session ID, or Workspace path."
-                  : "Loaded environment:none Sessions do not appear here. This is not proof that Core has no other Environments."}
-              </p>
-              {allObserved.length ? <button className="button outline" type="button" onClick={() => setQuery("")}>Clear search</button> : null}
-            </div>
-          )}
-        </section>
-      </div>
-    </section>
-  );
-}
diff --git a/apps/web/src/features/sessions/SessionsView.tsx b/apps/web/src/features/sessions/SessionsView.tsx
index 2969e90..4d7e91f 100644
--- a/apps/web/src/features/sessions/SessionsView.tsx
+++ b/apps/web/src/features/sessions/SessionsView.tsx
@@ -80,7 +80,7 @@ interface SessionsViewProps {
   ) => Promise<AgentSession | undefined>;
 }
 
-const executorSetupUrl = "https://github.com/MiniMax-AI-Dev/parsar/blob/main/services/agents-api/README.md#internal-execution-device-connection";
+const coreRuntimeSetupUrl = "https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#public-text-execution";
 
 function SessionsListSkeleton() {
   return (
@@ -192,6 +192,30 @@ function UnsupportedActionNotice() {
   );
 }
 
+function CancelActiveTurnButton({ busy, onCancel }: { busy: boolean; onCancel: () => void }) {
+  return (
+    <button
+      className="composer-action"
+      type="button"
+      onClick={onCancel}
+      disabled={busy}
+      aria-label="Cancel active Turn"
+      title="Cancel active Turn"
+    >
+      <Square size={13} fill="currentColor" strokeWidth={1.5} />
+    </button>
+  );
+}
+
+function CancelOnlyBar({ busy, onCancel }: { busy: boolean; onCancel: () => void }) {
+  return (
+    <section className="active-turn-cancel-bar" aria-label="Active Turn controls">
+      <p>Turn continuation is unavailable, but cancellation remains available.</p>
+      <CancelActiveTurnButton busy={busy} onCancel={onCancel} />
+    </section>
+  );
+}
+
 function FunctionActionBar({
   actions,
   agentName,
@@ -261,9 +285,7 @@ function FunctionActionBar({
         >
           Submit result
         </button>
-        <button className="composer-action" type="button" onClick={onCancel} disabled={busy} aria-label="Cancel active Turn" title="Cancel active Turn">
-          <Square size={13} fill="currentColor" strokeWidth={1.5} />
-        </button>
+        <CancelActiveTurnButton busy={busy} onCancel={onCancel} />
       </div>
     </section>
   );
@@ -434,6 +456,10 @@ export function SessionsView({
   const unsupportedActionCount = requiredActions.length - environmentConnections.length - functionActions.length + (
     !requiredActionsAreValid || selected?.status === "requires_action" && !requiredActions.length ? 1 : 0
   );
+  const showCancelOnly = Boolean(
+    (selected?.status === "in_progress" || selected?.status === "requires_action") &&
+    (unsupportedActionCount > 0 || environmentConnections.length > 0 && functionActions.length === 0),
+  );
 
   return (
     <section ref={pageRef} className="page-section session-page" tabIndex={-1}>
@@ -617,21 +643,21 @@ export function SessionsView({
                 {sendError ? (
                   <ErrorState
                     className="session-send-error"
-                    title={sendError.code === "execution_unavailable" ? "Execution daemon is unavailable" : "Message wasn’t sent"}
+                    title={sendError.code === "execution_unavailable" ? "Core execution is unavailable" : "Message wasn’t sent"}
                     description={sendError.code === "execution_unavailable"
-                      ? "Agent Core is online, but this service does not currently have an execution worker. Your draft was restored and was not retried."
+                      ? "Agent Core rejected this execution request. Your draft was restored and was not retried."
                       : sendError.uncertain
                         ? "Core may have accepted this message before the response was lost. Your draft was restored and was not retried."
                         : "Agent Core rejected the message. Your draft was restored and was not retried."}
                     detail={sendError.message}
                     hint={sendError.code === "execution_unavailable"
-                      ? "Start Core with AGENTS_API_DAEMON_WS_URL, connect a same-tenant parsar-daemon, then explicitly send the unchanged draft again."
+                      ? "Review the Core error and operator runtime configuration, then explicitly send the unchanged draft again when Core is ready."
                       : sendError.uncertain
                         ? "Review durable state first. Explicitly send the unchanged draft to reuse its key; editing it creates a new operation."
                         : "Review the error, then send the restored draft as a new operation when the Core is ready."}
                     action={sendError.code === "execution_unavailable" ? (
-                      <a className="button outline" href={executorSetupUrl} target="_blank" rel="noreferrer">
-                        Executor setup
+                      <a className="button outline" href={coreRuntimeSetupUrl} target="_blank" rel="noreferrer">
+                        Core runtime setup
                         <ExternalLink size={13} strokeWidth={1.5} aria-hidden="true" />
                       </a>
                     ) : undefined}
@@ -673,6 +699,9 @@ export function SessionsView({
               <EnvironmentConnectionNotice action={action} key={`${action.environment_id}:${index}`} />
             ))}
             {unsupportedActionCount ? <UnsupportedActionNotice /> : null}
+            {showCancelOnly ? (
+              <CancelOnlyBar busy={busy} onCancel={cancel} />
+            ) : null}
             {!unsupportedActionCount && functionActions.length ? (
                 <FunctionActionBar
                   actions={functionActions}
@@ -706,9 +735,7 @@ export function SessionsView({
                   <span>{selected.agent.name || "Untitled Agent"}</span>
                 </span>
                 {selected.status === "in_progress" || selected.status === "requires_action" ? (
-                  <button className="composer-action" type="button" onClick={cancel} disabled={busy} aria-label="Cancel active Turn" title="Cancel active Turn">
-                    <Square size={13} fill="currentColor" strokeWidth={1.5} />
-                  </button>
+                  <CancelActiveTurnButton busy={busy} onCancel={cancel} />
                 ) : (
                   <button
                     className="composer-action send"
diff --git a/apps/web/src/features/sessions/environment/EnvironmentPanel.tsx b/apps/web/src/features/sessions/environment/EnvironmentPanel.tsx
index 563549d..343ab09 100644
--- a/apps/web/src/features/sessions/environment/EnvironmentPanel.tsx
+++ b/apps/web/src/features/sessions/environment/EnvironmentPanel.tsx
@@ -10,7 +10,7 @@ import type {
 import { StatusIcon, type StatusKind } from "../../../components/StatusIcon";
 import { environmentIdsMatch, type EnvironmentObservation } from "./environment-state";
 
-const parsarBaseline = "0438880ab21aa16d05cb91a4c7f91cc0abc12358";
+const parsarBaseline = "d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee";
 const coreSetupUrl = `https://github.com/MiniMax-AI-Dev/parsar/blob/${parsarBaseline}/services/agents-api/README.md#native-executor-transport-prerequisite`;
 const launcherSetupUrl = `https://github.com/MiniMax-AI-Dev/parsar/blob/${parsarBaseline}/packages/codex-executor/README.md#connect-an-executor`;
 
diff --git a/apps/web/src/style.css b/apps/web/src/style.css
index 5580827..f59bbdb 100644
--- a/apps/web/src/style.css
+++ b/apps/web/src/style.css
@@ -2792,6 +2792,12 @@ button.trace-step-row:hover {
   color: var(--fg-muted);
 }
 
+.approval-input:disabled,
+.composer textarea:disabled {
+  cursor: not-allowed;
+  opacity: 0.62;
+}
+
 .approval-actions {
   display: flex;
   align-items: center;
@@ -2800,6 +2806,24 @@ button.trace-step-row:hover {
   gap: 8px;
 }
 
+.active-turn-cancel-bar {
+  display: flex;
+  width: 100%;
+  max-width: 736px;
+  min-height: 40px;
+  align-items: center;
+  justify-content: space-between;
+  margin: 0 auto;
+  gap: 12px;
+}
+
+.active-turn-cancel-bar > p {
+  margin: 0;
+  color: var(--fg-muted);
+  font-size: 12px;
+  line-height: 17px;
+}
+
 .composer {
   display: flex;
   width: 100%;
@@ -3797,8 +3821,7 @@ button.trace-step-row:hover {
   box-shadow: var(--shadow-floating);
 }
 
-.create-menu-panel > button,
-.create-menu-unavailable {
+.create-menu-panel > button {
   display: grid;
   grid-template-columns: 18px minmax(0, 1fr);
   min-height: 54px;
@@ -3816,8 +3839,7 @@ button.trace-step-row:hover {
   background: var(--hover);
 }
 
-.create-menu-panel > button:disabled,
-.create-menu-unavailable {
+.create-menu-panel > button:disabled {
   color: var(--fg-muted);
   opacity: 0.72;
 }
@@ -4145,235 +4167,6 @@ button.trace-step-row:hover {
   line-height: 17px;
 }
 
-/* Session-derived Environments overview. */
-
-.environments-page {
-  display: flex;
-  min-height: 0;
-  flex-direction: column;
-  overflow: hidden;
-}
-
-.environments-header > div:first-child {
-  min-width: 0;
-}
-
-.environments-header h1 span {
-  color: var(--fg-muted);
-  font-size: 12px;
-  font-weight: 400;
-}
-
-.environments-header p {
-  margin: 2px 0 0;
-  overflow: hidden;
-  color: var(--fg-muted);
-  font-size: 11px;
-  line-height: 15px;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-}
-
-.environments-header .search-control {
-  width: min(340px, 40vw);
-  margin-left: auto;
-}
-
-.environments-scroll {
-  min-height: 0;
-  padding: 22px 24px 48px;
-  overflow-y: auto;
-}
-
-.environment-catalog-boundary {
-  display: flex;
-  max-width: 960px;
-  padding: 12px 14px;
-  gap: 10px;
-  color: var(--fg);
-  background: color-mix(in srgb, var(--warning) 7%, var(--surface));
-  border: 1px solid color-mix(in srgb, var(--warning) 25%, var(--line));
-  border-radius: 8px;
-}
-
-.environment-catalog-boundary > svg {
-  flex: 0 0 auto;
-  margin-top: 1px;
-  color: var(--warning);
-}
-
-.environment-catalog-boundary strong {
-  font-size: 13px;
-  font-weight: 500;
-}
-
-.environment-catalog-boundary p {
-  margin: 2px 0 0;
-  color: var(--fg-muted);
-  font-size: 12px;
-  line-height: 17px;
-}
-
-.environment-unavailable-grid {
-  display: grid;
-  max-width: 960px;
-  margin-top: 14px;
-  grid-template-columns: repeat(2, minmax(0, 1fr));
-  gap: 10px;
-}
-
-.environment-unavailable-grid article {
-  display: grid;
-  grid-template-columns: 20px minmax(0, 1fr);
-  padding: 13px;
-  gap: 4px 9px;
-  background: var(--surface-subtle);
-  border: 1px solid var(--line);
-  border-radius: 8px;
-}
-
-.environment-unavailable-grid article > svg {
-  margin-top: 1px;
-  color: var(--fg-muted);
-}
-
-.environment-unavailable-grid article > div {
-  display: flex;
-  align-items: baseline;
-  justify-content: space-between;
-  gap: 8px;
-}
-
-.environment-unavailable-grid strong {
-  font-size: 13px;
-  font-weight: 500;
-}
-
-.environment-unavailable-grid span {
-  color: var(--fg-muted);
-  font-size: 10px;
-  text-transform: uppercase;
-}
-
-.environment-unavailable-grid p {
-  grid-column: 2;
-  margin: 0;
-  color: var(--fg-muted);
-  font-size: 11px;
-  line-height: 16px;
-}
-
-.observed-environments {
-  max-width: 960px;
-  margin-top: 26px;
-}
-
-.observed-environments > header {
-  display: flex;
-  align-items: flex-end;
-  justify-content: space-between;
-  margin-bottom: 9px;
-  gap: 12px;
-}
-
-.observed-environments h2 {
-  margin: 0;
-  font-size: 15px;
-  font-weight: 600;
-}
-
-.observed-environments header p {
-  margin: 2px 0 0;
-  color: var(--fg-muted);
-  font-size: 11px;
-  line-height: 16px;
-}
-
-.observed-environments > header > span {
-  color: var(--fg-muted);
-  font-family: var(--font-mono);
-  font-size: 12px;
-}
-
-.observed-environment-list {
-  display: grid;
-  gap: 10px;
-}
-
-.observed-environment {
-  overflow: hidden;
-  border: 1px solid var(--line);
-  border-radius: 8px;
-}
-
-.observed-environment > header {
-  display: flex;
-  min-height: 46px;
-  align-items: center;
-  justify-content: space-between;
-  padding: 7px 10px 7px 13px;
-  gap: 12px;
-  background: var(--surface-subtle);
-  border-bottom: 1px solid var(--line);
-}
-
-.observed-environment > header > div {
-  display: flex;
-  min-width: 0;
-  flex-direction: column;
-}
-
-.observed-environment > header strong {
-  font-size: 13px;
-  font-weight: 500;
-}
-
-.observed-environment > header span {
-  overflow: hidden;
-  color: var(--fg-muted);
-  font-size: 11px;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-}
-
-.observed-environment > header code {
-  font-family: var(--font-mono);
-  font-size: 10px;
-}
-
-.observed-environment > .environment-panel {
-  margin: 0;
-  border: 0;
-  border-radius: 0;
-}
-
-.environment-overview-empty {
-  display: flex;
-  min-height: 180px;
-  align-items: center;
-  justify-content: center;
-  padding: 24px;
-  flex-direction: column;
-  color: var(--fg-muted);
-  text-align: center;
-  background: var(--surface-subtle);
-  border: 1px dashed var(--line-strong);
-  border-radius: 8px;
-}
-
-.environment-overview-empty h3 {
-  margin: 9px 0 2px;
-  color: var(--fg);
-  font-size: 14px;
-  font-weight: 500;
-}
-
-.environment-overview-empty p {
-  max-width: 560px;
-  margin: 0 0 12px;
-  font-size: 12px;
-}
-
 @media (max-width: 1000px) {
   .agent-setup-layout {
     grid-template-columns: minmax(340px, 1fr) minmax(360px, 1fr);
@@ -4439,8 +4232,7 @@ button.trace-step-row:hover {
     border-top: 1px solid var(--line);
   }
 
-  .agent-form-grid,
-  .environment-unavailable-grid {
+  .agent-form-grid {
     grid-template-columns: 1fr;
   }
 
@@ -4453,30 +4245,6 @@ button.trace-step-row:hover {
     margin-left: 0;
   }
 
-  .environments-header {
-    min-height: auto;
-    flex: 0 0 auto;
-    flex-wrap: wrap;
-    padding: 10px 12px;
-  }
-
-  .environments-header .search-control {
-    width: 100%;
-    margin-left: 0;
-  }
-
-  .environments-scroll {
-    padding: 14px 12px 32px;
-  }
-
-  .observed-environment > header {
-    align-items: flex-start;
-    flex-direction: column;
-  }
-
-  .observed-environment > header .button {
-    width: 100%;
-  }
 }
 
 @keyframes overlay-in {
diff --git a/docs/architecture.md b/docs/architecture.md
index 91eb0d5..b7a3fa5 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -17,8 +17,8 @@ This boundary is intentional:
 - Core fixes and runtime-provider work are contributed upstream instead of copied or
   simulated in Web.
 
-The current compatibility baseline is Parsar
-[`0438880a`](https://github.com/MiniMax-AI-Dev/parsar/commit/0438880ab21aa16d05cb91a4c7f91cc0abc12358),
+The current compatibility audit baseline is Parsar
+[`d91ba48a`](https://github.com/MiniMax-AI-Dev/parsar/commit/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee),
 whose contract is pinned to `openai-python` 3.13.0 commit
 [`d7c41efe`](https://github.com/openai/openai-python/tree/d7c41efee1b0802b79f3f88a678ef2052b06e9ce/src/openai/resources/beta/agents).
 This is a fixed beta subset, not a claim that every current OpenAI Agents API
@@ -142,17 +142,19 @@ Session and Environment identity, request/event revisions, stream epoch, selecti
 and abort checks reject late state. The TypeScript client exposes Turn list/retrieve
 for diagnostics, but the current UI does not use them in recovery.
 
-The client never retries an uncertain write automatically. The current UI does not
-persist one generated idempotency key across a manual resend, so it must not imply
-that pressing Send again is a safe retry. Durable/live terminal precedence and
-pending-operation key persistence remain M1 hardening work.
+The client never retries an uncertain write automatically. It keeps a failed
+message payload and idempotency key in memory only for an explicit byte-for-byte
+unchanged manual resend. Editing the payload, changing Session/Core, receiving a
+successful exact HTTP 204, or receiving a permanent rejection creates a new
+operation. Any other 2xx fails closed and remains uncertain because the documented
+Session events contract admits writes only with 204.
 
 ## Runtime profiles
 
-The Web currently creates `environment: {"type":"none"}` Sessions. On Parsar
-`0438880a`, Core also contains a narrow Codex `self_hosted` profile for empty Sessions
-followed by constrained idle text input. The Web does not create or connect that
-profile, but for an already selected self-hosted Session it reads the durable
+The Web currently creates `environment: {"type":"none"}` Sessions. Parsar
+`d91ba48a` also exposes Session-bound `self_hosted` data and documented event inputs.
+The Web does not create or connect that profile, but for an already selected
+self-hosted Session it reads the durable
 Environment's exact safe projection and status. Durable `expired` and live-only
 `ready` remain separate states; empty installation arrays do not describe a host or
 Workspace. This profile is not equivalent to the internal daemon socket, Docker,
@@ -193,8 +195,10 @@ workaround.
 
 The development proxy is loopback-only convenience, not a production security
 boundary. Production must terminate TLS, authenticate Web users, authorize requests,
-and hold the Core bearer in a reverse proxy/BFF. See
-[Connecting Agent Core](core-connection.md) for the local setup and credential flow.
+and hold the Core bearer in a reverse proxy/BFF. Use the immutable
+[current Parsar setup guide](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md#standalone-http-service)
+for Core lifecycle and treat [Connecting Agent Core](core-connection.md) as a legacy
+Web runbook pinned to the older revision stated at its top.
 
 ## Sources
 
@@ -202,6 +206,6 @@ and hold the Core bearer in a reverse proxy/BFF. See
 - [Official OpenAI Agents API overview](https://developers.openai.com/api/docs/guides/agents-api/overview)
 - [Official OpenAI Session lifecycle](https://developers.openai.com/api/docs/guides/agents-api/sessions)
 - [Pinned `openai-python` Agents resources](https://github.com/openai/openai-python/tree/d7c41efee1b0802b79f3f88a678ef2052b06e9ce/src/openai/resources/beta/agents)
-- [Parsar Agents API contract at `0438880a`](https://github.com/MiniMax-AI-Dev/parsar/blob/0438880ab21aa16d05cb91a4c7f91cc0abc12358/contracts/agents-api/README.md)
-- [Parsar Environment contract at `0438880a`](https://github.com/MiniMax-AI-Dev/parsar/blob/0438880ab21aa16d05cb91a4c7f91cc0abc12358/contracts/agents-api/environments.md)
-- [Parsar standalone service guide at `0438880a`](https://github.com/MiniMax-AI-Dev/parsar/blob/0438880ab21aa16d05cb91a4c7f91cc0abc12358/services/agents-api/README.md)
+- [Parsar Agents API contract at `d91ba48a`](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/contracts/agents-api/README.md)
+- [Parsar Environment contract at `d91ba48a`](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/contracts/agents-api/environments.md)
+- [Parsar standalone service guide at `d91ba48a`](https://github.com/MiniMax-AI-Dev/parsar/blob/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee/services/agents-api/README.md)
diff --git a/docs/protocol-coverage.md b/docs/protocol-coverage.md
index c4f357c..22305b3 100644
--- a/docs/protocol-coverage.md
+++ b/docs/protocol-coverage.md
@@ -5,24 +5,25 @@ OpenAI-hosted service compatibility.
 
 ## Compatibility baseline
 
-- Parsar Core:
-  [`0438880a`](https://github.com/MiniMax-AI-Dev/parsar/commit/0438880ab21aa16d05cb91a4c7f91cc0abc12358)
-- The product-navigation, Agent execution-admission, and Environment-unavailable boundaries were re-audited
-  against Parsar [`c15d42a2`](https://github.com/MiniMax-AI-Dev/parsar/commit/c15d42a270c0667bcaa83a6b9d01a9892ebf7edd).
-  That revision still exposes only Environment retrieve plus Session-bound
-  `self_hosted` creation; it adds no public Environment list, template, file, or
-  browser-facing key management route.
+- Current Parsar Core compatibility audit:
+  [`d91ba48a`](https://github.com/MiniMax-AI-Dev/parsar/commit/d91ba48ac6c49cfdf6f08d7687b9be76ba6d53ee).
+  This immutable revision re-confirms the Web-used Agent admission, chat, and
+  Environment boundaries. `OpenAI-Beta: agents=v1` plus the `/v1/agents/**`
+  resources and Session events endpoint are the versioned Web/Core contract. Core
+  exposes no additional public execution-readiness, capability, or build-version
+  resource; Web does not require one before using the documented chat events. It
+  exposes Environment retrieve plus Session-bound `self_hosted` data, but no public
+  Environment list, template, file-management, or browser-facing key route.
 - Upstream resource source: `openai-python` 3.13.0 beta Agents resources at
   [`d7c41efe`](https://github.com/openai/openai-python/tree/d7c41efee1b0802b79f3f88a678ef2052b06e9ce/src/openai/resources/beta/agents)
 - Required beta header: `OpenAI-Beta: agents=v1`
 - Core base: same-origin `/v1` through the Web proxy for stock Parsar Core; a direct
   URL only for a compatible Core or proxy with explicit CORS support
 
-Parsar's pinned inventory contains 42 upstream operations in 15 resource classes;
-the referenced Core revision has handlers for 20 operations, and those handlers
-still implement partial request/event semantics. Importing an official SDK or
-accepting extra fields is not compatibility proof. Unsupported capabilities must
-fail explicitly.
+Parsar implements a partial subset of the pinned upstream resource inventory, and
+its handlers still implement partial request/event semantics. Importing an official
+SDK or accepting extra fields is not compatibility proof. Unsupported capabilities
+must fail explicitly.
 
 Requests use `Authorization: Bearer <execution-principal key>`. Optional
 `OpenAI-Organization` and `OpenAI-Project` headers, when present, must exactly match
@@ -37,21 +38,21 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 | Sessions create/list/retrieve | Yes | Yes | UI creates idle `environment:none` Sessions; client types also cover the pinned `self_hosted` request and safe response projection |
 | Sessions update/delete | Yes | Yes | Title/string metadata editing and one-Session confirmed deletion; no bulk or Workspace deletion |
 | Session live events | Yes | Yes | Authenticated `fetch` stream, not `EventSource` |
-| Input message | Yes | Yes | Opens SSE before submission; uncertain failures retain the in-memory payload/key for an explicit unchanged manual retry only |
+| Input message / steering | Yes | Yes | Opens SSE before submitting `agent.session.input.message`; only HTTP 204 is durable admission, while Core errors or an unexpected 2xx remain visible and uncertain failures retain the in-memory payload/key for an explicit unchanged manual retry only |
 | Active Turn cancel | Yes | Yes | Submitted as a Session event, not a Turn-create endpoint |
 | Turn list | Yes | Yes, read-only | Selected Sessions load every page in ascending creation order; no Turn mutation UI |
 | Turn retrieve | Yes | No | Reusable client diagnostic method; timeline recovery uses the all-pages list |
 | Item list/recovery | Yes | Yes | Authoritative recovery after stream loss |
 | Parsar `apply_patch` Item presentation | Existing function Item fields | Yes, read-only | Parsar extension recognized only for the pinned `changes[].{path,kind,diff}` shape; not an OpenAI standard Item type |
-| Function result/error | Yes | Yes | Initial UI supports text result/error handoff only for `function_call` actions |
+| Function result/error | Yes | Yes | Supports text `agent.session.input.tool_result` success/error handoff for exact `function_call` actions |
 | Initial-input creation stream | Later | No | Idle-create flow avoids the early-event race |
 | Artifacts/files | Later | No | Required Core resources are not implemented |
 | Environment connection action | Yes | Render-only | `environment_connection` is distinct from a function call; Web shows an operator-owned, non-actionable state and sends no result |
 | Environment lifecycle events | Yes | Read-only | UI projects pinned pending, ready, connected, disconnected, and failed live snapshots; unknown/malformed status events clear prior live claims and render as unavailable |
 | Environment retrieve | Yes | Yes, read-only | For a valid `self_hosted` Session Environment ID, reads the exact public resource fields and durable status; no create/list/update/delete support |
-| Environment overview | Session-derived only | Yes, read-only | Shows only `self_hosted` projections in currently loaded Sessions and their already-observed matching status; explicitly not a Core Environment catalog |
-| Environment templates | No | Explicitly unavailable | The navigation/Create surface does not simulate template reads or writes |
-| Environment keys | No public browser API | Explicitly unavailable | Operator-issued executor credentials never enter browser state or request previews |
+| Environment overview | No public list API | No top-level UI | Web does not turn loaded Session projections into a catalog; a selected Session may still show its exact Environment data |
+| Environment templates | No | Hidden | No navigation or Create entry is shown without a Core contract |
+| Environment keys | No public browser API | Hidden | Operator-issued executor credentials never enter browser state, request previews, navigation, or Create actions |
 | Vaults | Later | No | Credentials must never be stored in browser metadata |
 | Protocol Subagents / enabled multi-agent | Later | No | Distinct from storing multiple Agent configurations |
 | Usage/observability | Response types | Yes, scoped | Session aggregate and per-Turn token Usage are labelled separately; unavailable measurements remain unknown, not zero |
@@ -59,15 +60,22 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 ## Runtime boundary
 
 - The Web currently creates only `environment: {"type":"none"}` Sessions.
+- Message, active-Turn steering, cancel, and function-result/error writes use the
+  current `agents=v1` Session events contract. Web does not add a separate private
+  runtime-readiness gate. Only exact HTTP 204 denotes durable event admission;
+  every other status, including another 2xx, fails closed. HTTP acceptance, health,
+  Agent creation, and an open SSE stream still do not prove that execution will
+  complete; subsequent durable Session, Turn, and Item state is authoritative.
 - Product navigation and the global Create menu do not widen the protocol. Agent
-  and idle Session creation call the existing client methods. Environment template
-  and Environment key entries are non-actionable unavailable states.
+  and idle Session creation call the existing client methods. The top-level
+  Environments destination and Environment template/key entries are absent because
+  Core exposes no corresponding list or management APIs.
 - The Agent setup request preview is derived entirely from editable Agent fields and
   the sanitized Core base URL. Its authorization header always contains the literal
   `${AGENTS_CORE_API_KEY}` placeholder; it never reads or renders the connection's
   server-managed or current-tab bearer.
 - Saved Agent persistence and Session execution are separate contracts. Parsar
-  `c15d42a2` can store explicit reasoning, non-`auto` service tiers, and JSON-schema
+  `d91ba48a` can store explicit reasoning, non-`auto` service tiers, and JSON-schema
   text formats, but rejects each of them before creating a Session. Enabled
   multi-agent configuration, saved-only tool types, deferred/invalid/duplicate
   function or MCP identities, and MCP credentials without attached Vaults are
@@ -80,13 +88,9 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
 - Saved Agent names are limited to 128 Unicode characters. Agent metadata is limited
   to 16 string pairs, 64 Unicode characters per key, and 512 per value; the Web
   enforces those limits before a write.
-- The Environments overview filters the currently loaded Session collection to exact
-  `self_hosted` projections. A matching durable/live observation may annotate that
-  row, but an absent row or observation remains unknown. The view does not derive a
-  list from database state, Environment IDs, executor registrations, or operator keys.
-- Parsar Core at the pinned revision has a narrow `self_hosted` profile for empty
-  Session creation followed by constrained idle text input. The Web does not create
-  that profile, but it safely renders selected Sessions that already carry one. This
+- Parsar Core at the audited revision supports Session-bound `self_hosted` data and
+  its documented event inputs. This Web does not create or connect that profile; it
+  safely renders selected Sessions that already carry one. That read-only projection
   does not expand the missing Environment create/list/update/delete, template, or
   file-operation surface.
 - The reusable client distinguishes the admitted `self_hosted` request fields
@@ -161,7 +165,8 @@ the Core key binding. Agents Core Web's local proxy owns the bearer server-side.
   multi-agent, executable-tool-shape, and unattached-credential incompatibilities
   are authoritative at Session creation; a real Turn remains necessary to prove
   model/provider execution and conditional Codex `low`/`high` verbosity support.
-  Claude SDK accepts medium verbosity only.
+  Web never sends a paid Turn merely as a capability probe. Claude SDK accepts
+  medium verbosity only.
 
 Environment creation and management beyond the narrow read, provider selection,
 Files, Plugins, Skills, Artifacts, Vault, hosted runtimes, and Workspace lifecycle
@@ -297,14 +302,14 @@ read keeps the existing conversation usable.
   observability. They are not per-Item timing, monetary cost, provider attribution,
   or a complete OpenAI Trace waterfall.
 
-The client never retries a write automatically. For an input message that fails with
-a network/response-loss error, HTTP 5xx, or transient 408/409/425/429, the Web keeps
-the original payload and idempotency key in memory. Only a later user-initiated Send
-of the byte-for-byte unchanged payload reuses that key. Editing the payload, changing
-Session/Core, a successful response, or a permanent 4xx starts a new operation with a
-new key. This state is intentionally not stored in browser persistence, and the UI
-cannot prove whether an uncertain request was accepted until durable Core state
-reconciles.
+The client never retries a write automatically. For an input message that receives
+an unexpected non-204 2xx, loses its network/response, or fails with HTTP 5xx or a
+transient 408/409/425/429, the Web keeps the original payload and idempotency key in
+memory. Only a later user-initiated Send of the byte-for-byte unchanged payload
+reuses that key. Editing the payload, changing Session/Core, a successful response,
+or a permanent 4xx starts a new operation with a new key. This state is intentionally
+not stored in browser persistence, and the UI cannot prove whether an uncertain
+request was accepted until durable Core state reconciles.
 
 HTTP acceptance, `/healthz`, an open SSE connection, and successful Agent creation
 do not prove that a daemon, native harness, model ID, or provider credential can
diff --git a/packages/agents-client/src/client.test.ts b/packages/agents-client/src/client.test.ts
index 7b19dc3..c0aaecd 100644
--- a/packages/agents-client/src/client.test.ts
+++ b/packages/agents-client/src/client.test.ts
@@ -436,6 +436,38 @@ describe("OpenAIAgentsClient", () => {
     });
   });
 
+  it.each([
+    ["message", (client: OpenAIAgentsClient) => client.sendMessage("session", "hello", "event-key")],
+    ["cancel", (client: OpenAIAgentsClient) => client.cancelTurn("session", "event-key")],
+    ["tool result", (client: OpenAIAgentsClient) => client.submitFunctionResult("session", {
+      callId: "call_1",
+      turnId: "turn_1",
+      success: false,
+      error: "safe failure",
+    }, "event-key")],
+  ])("requires HTTP 204 for %s event submission without retrying", async (_label, submit) => {
+    const successCalls: FetchCall[] = [];
+    const successClient = new OpenAIAgentsClient({
+      fetch: recordingFetch(new Response(null, { status: 204 }), successCalls),
+    });
+
+    await expect(submit(successClient)).resolves.toBeUndefined();
+    expect(successCalls).toHaveLength(1);
+
+    for (const status of [200, 202]) {
+      const calls: FetchCall[] = [];
+      const client = new OpenAIAgentsClient({
+        fetch: recordingFetch(jsonResponse({ accepted: true }, status), calls),
+      });
+
+      await expect(submit(client)).rejects.toMatchObject({
+        status,
+        message: `Agent core request failed (${status}).`,
+      });
+      expect(calls).toHaveLength(1);
+    }
+  });
+
   it("rejects stream=true before the JSON create method performs a request", async () => {
     const calls: FetchCall[] = [];
     const client = new OpenAIAgentsClient({
diff --git a/packages/agents-client/src/client.ts b/packages/agents-client/src/client.ts
index 42433e6..bb4087c 100644
--- a/packages/agents-client/src/client.ts
+++ b/packages/agents-client/src/client.ts
@@ -264,11 +264,15 @@ export class OpenAIAgentsClient implements AgentCore {
   }
 
   private submitEvents(sessionId: string, events: unknown[], idempotencyKey = randomKey()): Promise<void> {
-    return this.request(`/agents/sessions/${encodeURIComponent(sessionId)}/events`, {
-      method: "POST",
-      headers: { "Idempotency-Key": idempotencyKey },
-      body: JSON.stringify({ events }),
-    });
+    return this.request<void>(
+      `/agents/sessions/${encodeURIComponent(sessionId)}/events`,
+      {
+        method: "POST",
+        headers: { "Idempotency-Key": idempotencyKey },
+        body: JSON.stringify({ events }),
+      },
+      204,
+    );
   }
 
   sendMessage(sessionId: string, text: string, idempotencyKey?: string): Promise<void> {