fix(desktop): rebind the Files pane cwd when switching sessions

Two defects left the Files pane showing the previous project's tree:

- `applyStoredSessionPreviewRuntimeInfo` reset every composer atom EXCEPT cwd,
  and runs before the `session.resume` RPC. The sidebar row already knows the
  conversation's workspace (`cwd` is in the compact row projection), so mirror
  it on the same tick the selection changes.

- `if (info.cwd)` was truthy-only, so a detached session reporting `cwd: ''`
  never cleared and the pane stayed pinned to the last project for the rest of
  the session — the "not always" in the report. Empty is now authoritative.

Empty routes through ownership release rather than a persisted `''`:
`setCurrentCwd` writes to localStorage and seeds `$currentCwd` on next boot, so
blanking would also wipe the remembered workspace.

Only `cwd` is consulted, never `git_repo_root` — the latter is documented null
for non-git workspaces and not-yet-backfilled rows, so falling back to it reads
as "no workspace" and blanks a pane that was correct. A session outside the
loaded sidebar page (no row at all) releases ownership instead of blanking, for
the same reason.

Also claims ownership on the warm-cache path (its missing-RPC compat branch
returns before `applyRuntimeInfo`) and for a center tile, whose Project "+"
create left the right rail on the previous session's folder.

Co-authored-by: xxxigm <tuancanhnguyen706@gmail.com>
Co-authored-by: worlldz <worlldz@users.noreply.github.com>
Co-authored-by: ZHJay <ZHJay@users.noreply.github.com>

apps/desktop/src/app/session/hooks/use-session-actions/index.ts

@@ -54,6 +54,7 @@ import {
   setSessions,
   setSessionStartedAt,
   setTurnStartedAt,
+  setWorkspaceCwdOwner,
   setYoloActive
 } from '@/store/session'
 import {
@@ -350,6 +351,11 @@ export function useSessionActions({
         setCurrentCwd(workspaceTarget)
       }
 
+      // A fresh draft resolves its own workspace right here, so it owns it. The
+      // selected stored id is null for a draft, and so is the owner — they match,
+      // which keeps workspace surfaces live on a new chat instead of treating the
+      // draft as an un-re-homed switch (#71254).
+      setWorkspaceCwdOwner(null)
       setCurrentBranch('')
       // Never clear the composer here — ChatBar's per-thread draft swap owns it.
       setFreshDraftReady(true)
@@ -514,13 +520,23 @@ export function useSessionActions({
           upsertOptimisticSession(created, stored, null, null)
         }
 
-        // A tile lives in its OWN worktree — it must not publish its cwd/branch
-        // into the composer atoms the main pane renders from.
+        // A tile lives in its OWN worktree, so it must not run the full
+        // foreground composer publish. A CENTER tile is the focused surface,
+        // though, and the Files pane still keys off the global `$currentCwd` —
+        // so the right rail kept showing the previous session's tree when a
+        // Project "+" created a session while the main chat was occupied
+        // (#76696). Split/side tiles deliberately stay isolated.
         const runtimeInfo = applyRuntimeInfo(created.info, { foreground: false })
         updateSessionState(created.session_id, state => (runtimeInfo ? { ...state, ...runtimeInfo } : state), stored)
 
         openSessionTile(stored, dir)
         patchSessionTile(stored, { runtimeId: created.session_id })
+
+        if (dir === 'center' && runtimeInfo?.cwd) {
+          setCurrentCwd(runtimeInfo.cwd)
+          setWorkspaceCwdOwner(stored)
+        }
+
         revealTreePane(`session-tile:${stored}`)
 
         if (listed) {
@@ -701,6 +717,12 @@ export function useSessionActions({
           activeSessionIdRef.current = cachedRuntimeId
           syncSessionStateToView(cachedRuntimeId, cachedViewState)
           setCurrentCwd(cachedViewState.cwd)
+          // The warm cache IS this conversation's own workspace truth, so the
+          // switch is already re-homed here. This claim cannot wait for
+          // `session.activate`: its missing-RPC compat branch returns before
+          // `applyRuntimeInfo` runs, which would leave the workspace marked
+          // un-owned for the life of the session (#71254).
+          setWorkspaceCwdOwner(storedSessionId)
           setCurrentBranch(cachedViewState.branch)
           setSessionStartedAt(Date.now())
 
@@ -844,7 +866,7 @@ export function useSessionActions({
       const stored =
         $sessions.get().find(session => sessionMatchesStoredId(session, storedSessionId)) ?? storedForProfile
 
-      applyStoredSessionPreviewRuntimeInfo(stored)
+      applyStoredSessionPreviewRuntimeInfo(stored, storedSessionId)
 
       if (stored) {
         applyStoredUsage(stored)

apps/desktop/src/app/session/hooks/use-session-actions/utils.ts

@@ -9,6 +9,8 @@ import { $activeGatewayProfile, $profiles, normalizeProfileKey } from '@/store/p
 import {
   $currentCwd,
   $sessions,
+  commitWorkspaceCwdForSelectedSession,
+  releaseWorkspaceCwdOwner,
   sessionMatchesStoredId,
   setCurrentBranch,
   setCurrentCwd,
@@ -20,6 +22,7 @@ import {
   setCurrentServiceTier,
   setCurrentUsage,
   setSessions,
+  setWorkspaceCwdOwner,
   setYoloActive
 } from '@/store/session'
 
@@ -959,7 +962,17 @@ function publishRuntimeToComposer(state: SessionRuntimeStatePatch): void {
   }
 
   if (state.cwd !== undefined) {
-    setCurrentCwd(state.cwd)
+    if (state.cwd) {
+      // The runtime named a real folder for the session in the main pane, so
+      // that conversation owns the path.
+      commitWorkspaceCwdForSelectedSession(state.cwd)
+    } else {
+      // A detached session: the path on screen is provably still the previous
+      // conversation's. Release rather than write `''` — `setCurrentCwd`
+      // persists, so blanking here would also wipe the remembered workspace
+      // that seeds `$currentCwd` on next boot.
+      releaseWorkspaceCwdOwner()
+    }
   }
 
   if (state.branch !== undefined) {
@@ -1017,7 +1030,12 @@ export function applyRuntimeInfo(
     sessionState.provider = info.provider
   }
 
-  if (info.cwd) {
+  // Empty string is authoritative, not "no opinion": a detached/bare session
+  // reports `cwd: ''`, and the truthy-only test left `$currentCwd` — and so the
+  // Files pane — pinned to the PREVIOUS project for the rest of the session
+  // (#71254). Empty is routed through ownership release below rather than
+  // persisted, so the pane hides a path it no longer owns instead of blanking.
+  if (typeof info.cwd === 'string') {
     sessionState.cwd = info.cwd
   }
 
@@ -1056,7 +1074,10 @@ export function applyRuntimeInfo(
   return sessionState
 }
 
-export function applyStoredSessionPreviewRuntimeInfo(stored: { model?: null | string } | undefined) {
+export function applyStoredSessionPreviewRuntimeInfo(
+  stored: { cwd?: null | string; model?: null | string } | undefined,
+  storedSessionId: null | string
+) {
   setCurrentModel(stored?.model || '')
   setCurrentProvider('')
   setCurrentReasoningEffort('')
@@ -1064,6 +1085,35 @@ export function applyStoredSessionPreviewRuntimeInfo(stored: { model?: null | st
   setCurrentFastMode(false)
   setYoloActive(false)
   setCurrentPersonality('')
+
+  // Cold resume paints the transcript before `session.resume` returns, so
+  // without this the Files pane shows the PREVIOUS project's tree for the whole
+  // round-trip (#71254 / #76696). The sidebar row already knows this
+  // conversation's workspace — `cwd` is part of the compact row projection — so
+  // mirror it on the same tick the selection changes.
+  //
+  // Only `cwd` is consulted. `git_repo_root` is documented as null for non-git
+  // workspaces and not-yet-backfilled history rows, so falling back to it would
+  // read as "no workspace" for those sessions and blank a pane that was correct.
+  const storedCwd = stored?.cwd?.trim() || ''
+
+  if (storedCwd) {
+    setCurrentCwd(storedCwd)
+    setWorkspaceCwdOwner(storedSessionId)
+  } else {
+    // Either a genuinely detached session, or a row outside the loaded sidebar
+    // page (`stored` is undefined) — neither says anything about the workspace,
+    // while `$currentCwd` still holds the previous conversation's folder.
+    // Release so workspace-derived surfaces stop trusting it; `applyRuntimeInfo`
+    // publishes the truth a moment later. The path is deliberately left in place
+    // — clearing it collapses the workspace/review panes and drops file-tree
+    // state on every switch.
+    releaseWorkspaceCwdOwner()
+  }
+
+  // Same window, same reasoning: the branch is derived from the workspace, so
+  // carrying the previous conversation's label across a switch is never right.
+  setCurrentBranch('')
 }
 
 // A "session genuinely doesn't exist" failure (deleted, or an id from a wiped /