fix(preview): derive file list from tool-edit history, not git diffs

packages/app/src/components/session/session-preview-tab.tsx

@@ -36,7 +36,10 @@ function preprocessMarkdown(text: string): string {
   return text.replace(/```math\n([\s\S]*?)```/g, (_match, body: string) => `$$\n${body.trim()}\n$$`)
 }
 
-export function SessionPreviewTab(props: { diffs: () => Array<{ file: string; status?: string }> }) {
+export function SessionPreviewTab(props: {
+  diffs: () => Array<{ file: string; status?: string }>
+  touchedFiles?: () => Array<{ file: string; status: string }>
+}) {
   const sdk = useSDK()
   const serverSDK = useServerSDK()
   const [selectedFile, setSelectedFile] = createSignal<string | undefined>(undefined)
@@ -48,24 +51,44 @@ export function SessionPreviewTab(props: { diffs: () => Array<{ file: string; st
   const zoomIn = () => setZoom((z) => Math.min(z + 10, 200))
   const zoomOut = () => setZoom((z) => Math.max(z - 10, 50))
 
-  // Filter diffs to only .md files
+  // Derive the file list from touchedFiles (tool-edit history, persists regardless of git state)
+  // supplemented by diffs for any files not already covered.
   const markdownFiles = createMemo((): PreviewFileEntry[] => {
-    return props
-      .diffs()
-      .filter((d) => d.file.endsWith(".md"))
-      .map((d) => {
-        const parts = d.file.split("/")
-        const basename = parts[parts.length - 1]
-        // relativePath: strip leading ~/ prefix
-        const relativePath = d.file.startsWith("~/") ? d.file.slice(2) : d.file
-        return {
-          path: d.file,
-          relativePath,
-          basename,
-          extension: ".md" as const,
-          changeType: (d.status === "added" ? "added" : "modified") as "added" | "modified",
-        }
-      })
+    const seen = new Set<string>()
+    const entries: PreviewFileEntry[] = []
+
+    const toEntry = (file: string, status: string): PreviewFileEntry | null => {
+      if (!file.endsWith(".md")) return null
+      if (seen.has(file)) return null
+      seen.add(file)
+      const parts = file.split("/")
+      const basename = parts[parts.length - 1]
+      const relativePath = file.startsWith("~/") ? file.slice(2) : file
+      return {
+        path: file,
+        relativePath,
+        basename,
+        extension: ".md" as const,
+        changeType: (status === "added" ? "added" : "modified") as "added" | "modified",
+      }
+    }
+
+    // Primary: all files touched by edit tools in this session
+    const touched = props.touchedFiles?.()
+    if (touched) {
+      for (const t of touched) {
+        const entry = toEntry(t.file, t.status)
+        if (entry) entries.push(entry)
+      }
+    }
+
+    // Supplement: any diff files not already in touchedFiles
+    for (const d of props.diffs()) {
+      const entry = toEntry(d.file, d.status === "added" ? "added" : "modified")
+      if (entry) entries.push(entry)
+    }
+
+    return entries
   })
 
   // Load file content when a file is selected

packages/app/src/pages/session.tsx

@@ -739,6 +739,39 @@ export default function Page() {
     }
     return accumulateDiffs(editParts)
   })
+
+  // All files touched by edit tools in this session — independent of git state.
+  // The Preview tab uses this so documents remain visible even after being committed/reverted.
+  const touchedFiles = createMemo(() => {
+    const allMessages = messages()
+    if (!allMessages.length) return [] as Array<{ file: string; status: string }>
+    const home = typeof globalThis.process !== "undefined" ? globalThis.process.env?.HOME : undefined
+    const toHomePath = (p: string) => {
+      if (p.startsWith("~/")) return p
+      if (home && p.startsWith(home)) return "~" + p.slice(home.length)
+      return p
+    }
+    const seen = new Map<string, string>()
+    for (const msg of allMessages) {
+      const msgParts = sync().data.part[msg.id]
+      if (!msgParts) continue
+      for (const part of msgParts) {
+        if (part.type !== "tool" || !EDIT_TOOLS.has(part.tool)) continue
+        if (part.state.status !== "completed") continue
+        const meta = part.state.metadata as Record<string, unknown> | undefined
+        const filediff = meta?.filediff as { file?: string } | undefined
+        if (filediff?.file) {
+          const normalized = toHomePath(filediff.file)
+          if (!seen.has(normalized)) {
+            // First touch of this file — check if it was created or modified
+            seen.set(normalized, part.tool === "write" ? "added" : "modified")
+          }
+        }
+      }
+    }
+    return Array.from(seen, ([file, status]) => ({ file, status }))
+  })
+
   const activeReviewFile = () => {
     const diffs = reviewDiffs()
     const selected = reviewFile()
@@ -2259,6 +2292,7 @@ export default function Page() {
               focusReviewDiff={focusReviewDiff}
               reviewSnap={ui.reviewSnap}
               size={size}
+              touchedFiles={touchedFiles}
             />
           </Suspense>
         </Show>
@@ -2311,6 +2345,7 @@ export default function Page() {
                       reviewSnap={ui.reviewSnap}
                       size={size}
                       stacked={desktopV2PanelLayout().stacked}
+                      touchedFiles={touchedFiles}
                     />
                   </Suspense>
                 </div>

packages/app/src/pages/session/session-side-panel.tsx

@@ -82,6 +82,7 @@ export function SessionSidePanel(props: {
   reviewSnap: boolean
   size: Sizing
   stacked?: boolean
+  touchedFiles?: () => Array<{ file: string; status: string }>
 }) {
   const layout = useLayout()
   const settings = useSettings()
@@ -245,9 +246,13 @@ export function SessionSidePanel(props: {
     return active !== "review" && active !== "context" && active !== "empty" && active !== SESSION_PREVIEW_TAB
   })
 
-  // Markdown files for the Preview tab (only shown when at least one .md file exists)
-  const markdownDiffs = createMemo(() => diffs().filter((d) => d.file.endsWith(".md")))
-  const hasMarkdownFiles = createMemo(() => markdownDiffs().length > 0)
+  // Markdown files for the Preview tab — check both git diffs and tool-edit history
+  const hasMarkdownFiles = createMemo(() => {
+    if (diffs().some((d) => d.file.endsWith(".md"))) return true
+    const touched = props.touchedFiles?.()
+    if (touched?.some((t) => t.file.endsWith(".md"))) return true
+    return false
+  })
 
   // Panel menu items
   const panelMenuItems = createMemo((): PanelMenuItem[] => [
@@ -528,7 +533,7 @@ export function SessionSidePanel(props: {
                           <Show when={activeTab() === SESSION_PREVIEW_TAB}>
                             <Tabs.Content value={SESSION_PREVIEW_TAB} class="flex flex-col h-full overflow-hidden contain-strict">
                               <div class="relative flex-1 min-h-0 overflow-hidden">
-                                <SessionPreviewTab diffs={diffs} />
+                                <SessionPreviewTab diffs={diffs} touchedFiles={props.touchedFiles} />
                               </div>
                             </Tabs.Content>
                           </Show>
@@ -737,11 +742,11 @@ export function SessionSidePanel(props: {
                         </Show>
 
                         <Show when={activeTab() === SESSION_PREVIEW_TAB}>
-                          <Tabs.Content value={SESSION_PREVIEW_TAB} class="flex flex-col h-full overflow-hidden contain-strict">
-                            <div class="relative flex-1 min-h-0 overflow-hidden">
-                              <SessionPreviewTab diffs={diffs} />
-                            </div>
-                          </Tabs.Content>
+                           <Tabs.Content value={SESSION_PREVIEW_TAB} class="flex flex-col h-full overflow-hidden contain-strict">
+                             <div class="relative flex-1 min-h-0 overflow-hidden">
+                               <SessionPreviewTab diffs={diffs} touchedFiles={props.touchedFiles} />
+                             </div>
+                           </Tabs.Content>
                         </Show>
 
                         <Show when={fileBrowserMounted()}>