feat(agent-panel): mid-session worktree switch confirmation

[liyakhar]

What

When the user enables the worktree toggle after a session is already active, Acepe now treats Continue as a real backend-owned runtime switch instead of a frontend metadata flip.

The dialog remains the product surface, but the Continue path now asks Rust to move the active session runtime to a new worktree so future prompts/tool calls run from that cwd.

Why

The first version of this PR created the worktree and updated UI/session metadata, but existing-session sends still called sendPrompt(sessionId, ...) on the already-registered provider client. That could make the UI say “worktree” while the live agent still operated in the original checkout.

How

• Added acp_switch_session_to_worktree Tauri command.
• Added a backend per-session switch gate so sends/model/mode/config/autonomous/cancel paths reject while a switch is in progress.
• Added managed worktree creation without prepared-launch reservation tokens, preventing new-session launch-token leaks.
• Runs worktree setup before provider rebind.
• Creates a replacement provider client rooted at the new worktree, reconnects the existing session ID, restores current model/mode where needed, persists worktreePath, then swaps the runtime in SessionRegistry.
• Frontend service now calls the backend switch command and no longer uses prepareWorktreeSessionLaunch, PreparedWorktreeLaunch, or pendingWorktreeEnabled for mid-session Continue.
• Added reviewed architecture plan: docs/plans/2026-05-20-mid-session-worktree-runtime-rebind-plan.md.

Also included from the original PR

• Worktree pill stays visible mid-session and after attach.
• Browser webview bounds stay synced during horizontal scroll.
• Terminal opens as a right-side trailing pane.
• Sidebar project cards no longer duplicate terminal/browser icons.

Validation

• cd packages/desktop && bun run check
• cd packages/desktop/src-tauri && cargo check --quiet
• cd packages/desktop/src-tauri && cargo clippy --quiet (passes with existing warnings)
• cd packages/desktop && bun test src/lib/acp/components/agent-panel/logic/__tests__/pre-session-worktree-card-visibility.test.ts

Deferred

Move session changes remains disabled. It should build on the same backend switch command after adding ownership-proof and transfer preflight.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[cubic-dev-ai]

2 issues found across 42 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/desktop/src-tauri/tauri.conf.json">

<violation number="1" location="packages/desktop/src-tauri/tauri.conf.json:25">
P1: Production hardening regression: enabling Tauri devtools unconditionally in `tauri.conf.json` exposes webview developer tools in packaged builds, allowing arbitrary JS execution. Change `devtools` back to `false` or guard it behind a debug-only config.</violation>
</file>

<file name="packages/ui/src/components/app-layout/project-tab-bar.svelte">

<violation number="1" location="packages/ui/src/components/app-layout/project-tab-bar.svelte:66">
P2: Hidden absolute `+` button remains interactive because it is hidden only via `opacity-0`, enabling accidental clicks and invisible keyboard focus.</violation>
</file>

<sub>Tip: cubic can generate docs of your entire codebase and keep them up to date. Try it here.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Production hardening regression: enabling Tauri devtools unconditionally in tauri.conf.json exposes webview developer tools in packaged builds, allowing arbitrary JS execution. Change devtools back to false or guard it behind a debug-only config.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/desktop/src-tauri/tauri.conf.json, line 25:

<comment>Production hardening regression: enabling Tauri devtools unconditionally in `tauri.conf.json` exposes webview developer tools in packaged builds, allowing arbitrary JS execution. Change `devtools` back to `false` or guard it behind a debug-only config.</comment>

<file context>
@@ -22,7 +22,7 @@
 				"titleBarStyle": "Overlay",
 				"dragDropEnabled": true,
-				"devtools": false
+				"devtools": true
 			}
 		],
</file context>

Suggested change

	"devtools": true
	"devtools": false

[cubic-dev-ai]

P2: Hidden absolute + button remains interactive because it is hidden only via opacity-0, enabling accidental clicks and invisible keyboard focus.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/ui/src/components/app-layout/project-tab-bar.svelte, line 66:

<comment>Hidden absolute `+` button remains interactive because it is hidden only via `opacity-0`, enabling accidental clicks and invisible keyboard focus.</comment>

<file context>
@@ -30,52 +30,53 @@
 						{/if}
-				</button>
+					</button>
+					{#if project.sessionCount != null && onCreateSession}
+						<button
+							type="button"
</file context>

[liyakhar]

P1: enabling Tauri devtools unconditionally in tauri.conf.json exposes webview developer tools in packaged builds

Fixed: set devtools back to false in tauri.conf.json.

P2: Hidden absolute + button remains interactive because it is hidden only via opacity-0

Fixed: added pointer-events-none to the hidden state and group-hover/session-badge:pointer-events-auto to restore interactivity on hover, preventing accidental clicks and invisible keyboard focus when the button is not visible.

[cubic-dev-ai]

2 issues found across 35 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/desktop/src-tauri/src/acp/commands/session_commands.rs">

<violation number="1" location="packages/desktop/src-tauri/src/acp/commands/session_commands.rs:1248">
P1: Post-reconnect error paths in acp_switch_session_to_worktree leak replacement_client and worktree on failure</violation>
</file>

<file name="packages/desktop/src-tauri/src/acp/commands/interaction_commands.rs">

<violation number="1" location="packages/desktop/src-tauri/src/acp/commands/interaction_commands.rs:250">
P2: Blocking `acp_cancel` during session switch violates established design principle that cancellation must remain gated on connection status, not send readiness or temporary operation locks</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Post-reconnect error paths in acp_switch_session_to_worktree leak replacement_client and worktree on failure

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/desktop/src-tauri/src/acp/commands/session_commands.rs, line 1248:

<comment>Post-reconnect error paths in acp_switch_session_to_worktree leak replacement_client and worktree on failure</comment>

<file context>
@@ -1145,6 +1146,164 @@ pub async fn acp_new_session(
+                }
+            };
+
+            if let Some(capabilities) = previous_capabilities {
+                if let Some(model_state) = capabilities.models {
+                    if let Some(model_id) = model_state.current_model_id {
</file context>

[cubic-dev-ai]

P2: Blocking acp_cancel during session switch violates established design principle that cancellation must remain gated on connection status, not send readiness or temporary operation locks

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/desktop/src-tauri/src/acp/commands/interaction_commands.rs, line 250:

<comment>Blocking `acp_cancel` during session switch violates established design principle that cancellation must remain gated on connection status, not send readiness or temporary operation locks</comment>

<file context>
@@ -247,6 +247,7 @@ pub(crate) async fn acp_set_model_for_handle<R: tauri::Runtime>(
     expected_acp_command_result(
         "acp_set_model",
         async {
+            super::session_switch_gate::reject_if_session_switching(&session_id)?;
             tracing::debug!(session_id = %session_id, model_id = %model_id, "acp_set_model called");
             let session_registry = app.state::<SessionRegistry>();
</file context>

Suggested change

	super::session_switch_gate::reject_if_session_switching(&session_id)?;
	// Do NOT gate cancel on session switch; cancellation must remain
	// available based on connection status per design guidance.
	// (Remove this line; keep the rest of the function unchanged.)

[cubic-dev-ai]

No issues found across 35 files

_{Re-trigger cubic}