refactor(ProjectScanner): enhance file detail retrieval and session metadata handling

- Updated the ProjectScanner class to utilize a new asynchronous method for resolving file details, improving accuracy in file metadata retrieval.
- Introduced birthtimeMs to session file information, ensuring comprehensive metadata is available for session management.
- Adjusted session creation logic to account for the new birthtimeMs, enhancing the integrity of session timestamps.
- Improved the handling of auto-scroll behavior in ChatHistory and useAutoScrollBottom hook, allowing for smoother user experience during content updates.

This commit enhances the ProjectScanner's efficiency and improves user experience in chat history management.

src/main/services/discovery/ProjectScanner.ts

@@ -416,8 +416,10 @@ export class ProjectScanner {
         sessionFiles.map(async (file) => {
           const sessionId = extractSessionId(file.name);
           const filePath = path.join(projectPath, file.name);
-          const prefetchedMtimeMs = file.mtimeMs;
+          const fileDetails = await this.resolveFileDetails(file, filePath);
-          const prefetchedSize = file.size;
+          const prefetchedMtimeMs = fileDetails.mtimeMs;
+          const prefetchedSize = fileDetails.size;
+          const prefetchedBirthtimeMs = fileDetails.birthtimeMs;
 
           if (shouldFilterNoise) {
             // Check if session has non-noise messages (delegated to SessionContentFilter)
@@ -438,7 +440,8 @@ export class ProjectScanner {
             filePath,
             decodedPath,
             prefetchedMtimeMs,
-            prefetchedSize
+            prefetchedSize,
+            prefetchedBirthtimeMs
           );
         })
       );
@@ -503,6 +506,7 @@ export class ProjectScanner {
         filePath: string;
         mtimeMs: number;
         size: number;
+        birthtimeMs: number;
       }
 
       const fileInfos = await this.collectFulfilledInBatches(
@@ -518,6 +522,7 @@ export class ProjectScanner {
             filePath,
             mtimeMs: fileDetails.mtimeMs,
             size: fileDetails.size,
+            birthtimeMs: fileDetails.birthtimeMs,
           } satisfies SessionFileInfo;
         }
       );
@@ -642,7 +647,8 @@ export class ProjectScanner {
               fileInfo.filePath,
               decodedPath,
               fileInfo.mtimeMs,
-              fileInfo.size
+              fileInfo.size,
+              fileInfo.birthtimeMs
             )
         );
         sessions.push(...builtSessions);
@@ -703,14 +709,17 @@ export class ProjectScanner {
     filePath: string,
     projectPath: string,
     prefetchedMtimeMs?: number,
-    prefetchedSize?: number
+    prefetchedSize?: number,
+    prefetchedBirthtimeMs?: number
   ): Promise<Session> {
-    const usePrefetchedStats =
+    const hasPrefetchedCoreStats =
       typeof prefetchedMtimeMs === 'number' && typeof prefetchedSize === 'number';
-    const stats = usePrefetchedStats ? null : await this.fsProvider.stat(filePath);
+    const needsBirthtimeStat = typeof prefetchedBirthtimeMs !== 'number';
+    const stats =
+      hasPrefetchedCoreStats && !needsBirthtimeStat ? null : await this.fsProvider.stat(filePath);
     const effectiveMtime = prefetchedMtimeMs ?? stats?.mtimeMs ?? Date.now();
     const effectiveSize = prefetchedSize ?? stats?.size ?? -1;
-    const birthtimeMs = stats?.birthtimeMs ?? effectiveMtime;
+    const birthtimeMs = prefetchedBirthtimeMs ?? stats?.birthtimeMs ?? effectiveMtime;
     const cachedMetadata = this.sessionMetadataCache.get(filePath);
     const metadata =
       cachedMetadata?.mtimeMs === effectiveMtime && cachedMetadata.size === effectiveSize
@@ -730,13 +739,18 @@ export class ProjectScanner {
       this.loadTodoData(sessionId),
     ]);
     const metadataLevel: SessionMetadataLevel = 'deep';
+    const firstMessageTimestampMs = this.parseTimestampMs(metadata.firstUserMessage?.timestamp);
+    const createdAt =
+      firstMessageTimestampMs !== null && Number.isFinite(firstMessageTimestampMs)
+        ? firstMessageTimestampMs
+        : birthtimeMs;
 
     return {
       id: sessionId,
       projectId,
       projectPath,
       todoData,
-      createdAt: Math.floor(birthtimeMs),
+      createdAt: Math.floor(createdAt),
       firstMessage: metadata.firstUserMessage?.text,
       messageTimestamp: metadata.firstUserMessage?.timestamp,
       hasSubagents,
@@ -757,14 +771,17 @@ export class ProjectScanner {
     filePath: string,
     projectPath: string,
     prefetchedMtimeMs?: number,
-    prefetchedSize?: number
+    prefetchedSize?: number,
+    prefetchedBirthtimeMs?: number
   ): Promise<Session> {
-    const usePrefetchedStats =
+    const hasPrefetchedCoreStats =
       typeof prefetchedMtimeMs === 'number' && typeof prefetchedSize === 'number';
-    const stats = usePrefetchedStats ? null : await this.fsProvider.stat(filePath);
+    const needsBirthtimeStat = typeof prefetchedBirthtimeMs !== 'number';
+    const stats =
+      hasPrefetchedCoreStats && !needsBirthtimeStat ? null : await this.fsProvider.stat(filePath);
     const effectiveMtime = prefetchedMtimeMs ?? stats?.mtimeMs ?? Date.now();
     const effectiveSize = prefetchedSize ?? stats?.size ?? -1;
-    const birthtimeMs = stats?.birthtimeMs ?? effectiveMtime;
+    const birthtimeMs = prefetchedBirthtimeMs ?? stats?.birthtimeMs ?? effectiveMtime;
     const cachedPreview = this.sessionPreviewCache.get(filePath);
     const preview =
       cachedPreview?.mtimeMs === effectiveMtime && cachedPreview.size === effectiveSize
@@ -778,12 +795,17 @@ export class ProjectScanner {
       });
     }
     const metadataLevel: SessionMetadataLevel = 'light';
+    const previewTimestampMs = this.parseTimestampMs(preview?.timestamp);
+    const createdAt =
+      previewTimestampMs !== null && Number.isFinite(previewTimestampMs)
+        ? previewTimestampMs
+        : birthtimeMs;
 
     return {
       id: sessionId,
       projectId,
       projectPath,
-      createdAt: Math.floor(birthtimeMs),
+      createdAt: Math.floor(createdAt),
       firstMessage: preview?.text,
       messageTimestamp: preview?.timestamp,
       hasSubagents: false,
@@ -803,7 +825,8 @@ export class ProjectScanner {
     filePath: string,
     projectPath: string,
     prefetchedMtimeMs?: number,
-    prefetchedSize?: number
+    prefetchedSize?: number,
+    prefetchedBirthtimeMs?: number
   ): Promise<Session> {
     if (metadataLevel === 'light') {
       return this.buildLightSessionMetadata(
@@ -812,7 +835,8 @@ export class ProjectScanner {
         filePath,
         projectPath,
         prefetchedMtimeMs,
-        prefetchedSize
+        prefetchedSize,
+        prefetchedBirthtimeMs
       );
     }
 
@@ -823,7 +847,8 @@ export class ProjectScanner {
         filePath,
         projectPath,
         prefetchedMtimeMs,
-        prefetchedSize
+        prefetchedSize,
+        prefetchedBirthtimeMs
       );
     } catch (error) {
       // In SSH mode, never drop a visible session row due to transient deep-parse failures.
@@ -838,7 +863,8 @@ export class ProjectScanner {
         filePath,
         projectPath,
         prefetchedMtimeMs,
-        prefetchedSize
+        prefetchedSize,
+        prefetchedBirthtimeMs
       );
     }
   }
@@ -1069,6 +1095,14 @@ export class ProjectScanner {
     };
   }
 
+  private parseTimestampMs(timestamp: string | undefined): number | null {
+    if (!timestamp) {
+      return null;
+    }
+    const parsed = Date.parse(timestamp);
+    return Number.isFinite(parsed) ? parsed : null;
+  }
+
   /**
    * Runs async mapping in bounded batches and returns only fulfilled results.
    * This prevents overwhelming SFTP servers with unbounded parallel requests.

src/renderer/components/chat/ChatHistory.tsx

@@ -339,13 +339,13 @@ export const ChatHistory = ({ tabId }: ChatHistoryProps): JSX.Element => {
     rootRef: scrollContainerRef,
   });
 
-  // Auto-scroll to bottom when new content is added
+  // Auto-follow when conversation updates, but only if the user was already near bottom.
-  // Disabled during navigation to prevent conflicts with deep link scrolling
+  // This preserves manual reading position when the user scrolls up.
-  // Uses shared scrollContainerRef created above
+  // Disabled during navigation to prevent conflicts with deep-link/search scrolling.
-  // resetKey ensures auto-scroll state resets when switching tabs/sessions
+  useAutoScrollBottom([conversation], {
-  useAutoScrollBottom([conversation?.items.length], {
     threshold: 150,
     smoothDuration: 300,
+    autoBehavior: 'auto',
     disabled: shouldDisableAutoScroll,
     externalRef: scrollContainerRef,
     resetKey: effectiveTabId,

src/renderer/hooks/useAutoScrollBottom.ts

@@ -22,6 +22,12 @@ interface UseAutoScrollBottomOptions {
    */
   enabled?: boolean;
 
+  /**
+   * Scroll behavior used for automatic follow when content updates.
+   * Default: 'smooth'
+   */
+  autoBehavior?: ScrollBehavior;
+
   /**
    * Whether auto-scroll is temporarily disabled (e.g., during navigation).
    * Unlike enabled, this is for transient disabling during specific operations.
@@ -115,6 +121,7 @@ export function useAutoScrollBottom(
     threshold = 100,
     smoothDuration = 300,
     enabled = true,
+    autoBehavior = 'smooth',
     disabled = false,
     externalRef,
     resetKey,
@@ -241,11 +248,11 @@ export function useAutoScrollBottom(
 
       // Only auto-scroll if user was at bottom before the update
       if (wasAtBottomBeforeUpdateRef.current) {
-        scrollToBottom('smooth');
+        scrollToBottom(autoBehavior);
       }
     });
     // eslint-disable-next-line react-hooks/exhaustive-deps -- Dynamic dependencies array is intentional design
-  }, [...dependencies, enabled, disabled, scrollToBottom]);
+  }, [...dependencies, enabled, disabled, autoBehavior, scrollToBottom]);
 
   /**
    * Getter function for isAtBottom to avoid accessing ref.current during render.

src/renderer/store/index.ts

@@ -73,9 +73,10 @@ export function initializeNotificationListeners(): () => void {
 
   const scheduleSessionRefresh = (projectId: string, sessionId: string): void => {
     const key = `${projectId}/${sessionId}`;
-    const existingTimer = pendingSessionRefreshTimers.get(key);
+    // Throttle (not trailing debounce): keep at most one pending refresh per session.
-    if (existingTimer) {
+    // Debounce can delay updates indefinitely while the file is continuously appended.
-      clearTimeout(existingTimer);
+    if (pendingSessionRefreshTimers.has(key)) {
+      return;
     }
     const timer = setTimeout(() => {
       pendingSessionRefreshTimers.delete(key);
@@ -218,25 +219,26 @@ export function initializeNotificationListeners(): () => void {
       const matchesSelectedProject =
         !!selectedProjectId &&
         (eventProjectBaseId == null || selectedProjectBaseId === eventProjectBaseId);
+      const isTopLevelSessionEvent = !event.isSubagent;
       const isUnknownSessionInSidebar =
-        event.sessionId != null && !state.sessions.some((session) => session.id === event.sessionId);
+        event.sessionId == null || !state.sessions.some((session) => session.id === event.sessionId);
       const shouldRefreshForPotentialNewSession =
-        event.type === 'change' &&
+        isTopLevelSessionEvent &&
-        !event.isSubagent &&
         matchesSelectedProject &&
-        state.connectionMode === 'local' &&
+        isUnknownSessionInSidebar &&
-        isUnknownSessionInSidebar;
+        (event.type === 'add' || (state.connectionMode === 'local' && event.type === 'change'));
 
-      // Refresh sidebar session list when a new top-level session is detected.
+      // Refresh sidebar session list only when a truly new top-level session appears.
-      // In local mode, some files can be observed as "change" before/without "add".
+      // Local fs.watch can report "change" before/without "add" for newly created files.
-      if ((event.type === 'add' && !event.isSubagent) || shouldRefreshForPotentialNewSession) {
+      if (shouldRefreshForPotentialNewSession) {
         if (matchesSelectedProject && selectedProjectId) {
           scheduleProjectRefresh(selectedProjectId);
         }
       }
 
       // Keep opened session view in sync on content changes.
-      if (event.type === 'change' && selectedProjectId) {
+      // Some local writers emit rename/add for in-place updates, so include "add".
+      if ((event.type === 'change' || event.type === 'add') && selectedProjectId) {
         const activeSessionId = state.selectedSessionId;
         const eventSessionId = event.sessionId;
         const isViewingEventSession =

src/renderer/store/slices/sessionDetailSlice.ts

@@ -462,14 +462,14 @@ export const createSessionDetailSlice: StateCreator<AppState, [], [], SessionDet
     }
 
     const refreshKey = `${projectId}/${sessionId}`;
-    const generation = (sessionRefreshGeneration.get(refreshKey) ?? 0) + 1;
-    sessionRefreshGeneration.set(refreshKey, generation);
 
     // Coalesce duplicate in-flight refreshes for the same session.
     if (sessionRefreshInFlight.has(refreshKey)) {
       sessionRefreshQueued.add(refreshKey);
       return;
     }
+    const generation = (sessionRefreshGeneration.get(refreshKey) ?? 0) + 1;
+    sessionRefreshGeneration.set(refreshKey, generation);
     sessionRefreshInFlight.add(refreshKey);
 
     try {
@@ -501,10 +501,10 @@ export const createSessionDetailSlice: StateCreator<AppState, [], [], SessionDet
       }
 
       const latestState = get();
-      const latestActiveTab = latestState.getActiveTab();
+      const latestAllTabs = getAllTabs(latestState.paneLayout);
       const stillViewingSession =
         latestState.selectedSessionId === sessionId ||
-        (latestActiveTab?.type === 'session' && latestActiveTab.sessionId === sessionId);
+        latestAllTabs.some((tab) => tab.type === 'session' && tab.sessionId === sessionId);
       if (!stillViewingSession) {
         return;
       }
@@ -532,17 +532,14 @@ export const createSessionDetailSlice: StateCreator<AppState, [], [], SessionDet
         }
       }
 
-      // Also update the session's isOngoing in the sessions array
-      // This keeps the sidebar in sync with the chat view
-      const updatedSessions = currentState.sessions.map((s) =>
-        s.id === sessionId ? { ...s, isOngoing: detail.session?.isOngoing ?? false } : s
-      );
-
       // Update only the data, preserve UI states
-      set({
+      set((state) => ({
         sessionDetail: detail,
         conversation: newConversation,
-        sessions: updatedSessions,
+        // Update on latest sessions state to avoid restoring stale sidebar snapshots.
+        sessions: state.sessions.map((s) =>
+          s.id === sessionId ? { ...s, isOngoing: detail.session?.isOngoing ?? false } : s
+        ),
         // Preserve visible group if it still exists, otherwise keep current
         ...(visibleGroupStillExists
           ? {
@@ -551,11 +548,10 @@ export const createSessionDetailSlice: StateCreator<AppState, [], [], SessionDet
           : {}),
         // Note: aiGroupExpansionLevels and expandedStepIds are NOT touched
         // so expansion states are preserved
-      });
+      }));
 
       // Also update per-tab session data for all tabs viewing this session
       const latestTabSessionData = { ...get().tabSessionData };
-      const latestAllTabs = getAllTabs(get().paneLayout);
       for (const tab of latestAllTabs) {
         if (tab.type === 'session' && tab.sessionId === sessionId && latestTabSessionData[tab.id]) {
           const tabData = latestTabSessionData[tab.id];