fix(files): list the git worktree an agent moved into (#765)

Claude Code's EnterWorktree moves the running process into
<repo>/.claude/worktrees/<name>, while Session.workingDir stays on the main
checkout. The Files panel kept walking workingDir, so it listed a tree the
agent had left.

paneCwd already follows the move, measured on Claude Code 2.1.318 in both
directions, so nothing new has to track the agent. It also follows every cd
in a shell, so a new SessionState.liveWorktree narrows it to a linked
worktree, read from the .git file without starting git.

Only a folder strictly below workingDir is ever an answer, and the listing
only starts there: returned paths stay relative to workingDir, so the
preview, raw and edit routes are unchanged and confinement does not widen.
A worktree outside the session folder stays unfollowed.

The panel asks with root=live, shows a strip naming the worktree with a
switch to the session folder, and follows the agent in and out while open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.changeset/files-panel-live-worktree.md

@@ -0,0 +1,5 @@
+---
+"aicodeman": patch
+---
+
+Files panel: when a session's agent moves into a git worktree part way through (Claude Code's EnterWorktree), the panel now lists that worktree instead of the main checkout, follows the agent back out, and shows a strip that names the worktree with a button to switch to the session's folder. Only a worktree inside the session's folder is followed, and file access stays confined to that folder as before.

CLAUDE.md

@@ -238,6 +238,8 @@ The terminal provider scans `terminalLinkLine()`, which extends `terminalPathLin
 
 **Files panel search** (COD-236, the `q` param on `GET /api/sessions/:id/files`): `compileFileQuery()` (`utils/file-query.ts`, pure) compiles the query into a predicate the server-side walk prunes with; a query returns a FLAT match list and the walk recurses past non-matching directories. An empty, whitespace-only or overlong (`MAX_QUERY_LENGTH`, 256) query compiles to `null`, keeping the default tree response byte-identical. ⚠️ **Never compile a glob into a RegExp** (`*a*a*a…` backtracks and freezes the event loop for the whole server): `globMatch()` is a two-pointer wildcard walk. → [architecture-invariants#files-panel-search](docs/architecture-invariants.md#files-panel-search)
 
+**Files panel in a worktree** (#765, `src/live-worktree.ts`, `root=live` on `GET /api/sessions/:id/files`): Claude's EnterWorktree moves the process, and `paneCwd` follows it (tmux reads the process cwd, measured on 2.1.318, back out on ExitWorktree too), while `workingDir` stays the session's identity. `refreshLiveWorktree()` (server.ts) turns a changed `paneCwd` into `SessionState.liveWorktree` by reading the `.git` FILE (never spawning git), walking up and stopping at `workingDir`, a repository or submodule of its own, or anything unreadable. ⚠️ Only a folder strictly below `workingDir` is ever an answer, which is the whole security argument: the walk starts there, returned `path`s stay relative to `workingDir`, and the routes keep confining to `workingDir`, so never make `liveWorktree` a confinement root (a worktree outside the folder stays unfollowed). ⚠️ A plain subfolder is deliberately no answer, or a `cd` in a shell would re-root the panel. ⚠️ A listing reports `worktree` whichever folder it walked, even when the worktree has gone: `_followFileBrowserWorktree()` compares that with the session's state, and an absent report would reload forever. Tests: `test/live-worktree.test.ts`, `test/routes/file-routes-live-worktree.test.ts`, `test/file-browser-worktree.test.ts`.
+
 **Git status indicator** (`showGitStatus`, per-device, default OFF; `src/git-workspace-status.ts`, `routes/git-status-routes.ts`, `git-status-ui.js`): the bottom-bar indicator and its panel read `GET /api/sessions/:id/git-status` and `/git-diff`, read-only and offline on its own (it never fetches; fetching is the separate path below). ⚠️ git never runs on a repository at or inside a Docker case workspace (walk-up, scan and diff alike, and a cached repository list is re-checked against the CURRENT Docker roots), since a container could plant a clean filter that runs on the host; remote and Docker sessions answer `unsupported`. ⚠️ `git-diff` takes `repo`/`path`/`kind` only as keys matched against the workspace's own repository list (`findWorkspaceRepo()`) and that repository's current status, never as paths. ⚠️ Keep `--no-optional-locks`, `core.fsmonitor=false` and `log.showSignature=false` on every call and `--no-ext-diff --no-textconv` on diffs; clean filters still run, which is why the Docker rule exists. ⚠️ An enclosing repository at `$HOME` or above is ignored (`isUnrelatedAncestor()`), and is identified by one cached `rev-parse` before any full status runs. Everything git supplies renders via `textContent`. Tests: `test/git-workspace-status.test.ts`, `test/routes/git-status-routes.test.ts`, and `test/git-status.browser.test.ts` (browser suite, not in the gate).
 
 **Git fetch** (`src/git-fetch.ts`, `src/git-fetch-scheduler.ts`, `routes/git-status-routes.ts`, the panel's **Fetch** button): `POST /api/sessions/:id/git-fetch` is the ONLY git command the Git PANEL runs that WRITES (cloning and worktree management write too, but only when the user asked for them at that moment), and it is the only one that can run later by itself, on a timer, and the only one that can run a repository's own hooks (`reference-transaction`, `pre-auto-gc` through the automatic maintenance a fetch triggers, config commands such as `credential.helper`), which is why it is opt-in and never runs on a timer until the user turns it on. ⚠️ Fetch updates remote-tracking refs only; it must never commit, check out, merge or touch the working tree. ⚠️ It is not as harmless as a read: a fetch holds git's ref lock, so an agent's own `git pull` in the same clone can hit the same `cannot lock ref`, hence one folder is fetched by at most one run at a time (`fetchWorkspaceOnce` joins a run already going), and `FETCH_CONFIG_ARGS` (`-c core.fsmonitor=false -c maintenance.auto=false -c gc.auto=0`) keeps an unattended fetch from starting a gc in a repository the agent is using. ⚠️ `buildFetchArgs()` is `['fetch', '--quiet']` and must stay verb-invariant (`test/git-fetch.test.ts`); those `-c` overrides are added by the runner, not by `buildFetchArgs()`. ⚠️ The git timeout must reach the whole process TREE, not just the `git` parent: `execFile` signals the parent only, so `runFetch` spawns `detached` and signals the negative pid (SIGTERM, then SIGKILL `FETCH_KILL_ESCALATION_MS` later), and the caller is answered AT the timeout while the group is still dying: that is the point. `test/git-fetch.test.ts` proves it against a local server that never answers, by group membership rather than parentage. A non-zero exit must still reject the way `execFile` would, or a real failure reads as a clean run with no reason. ⚠️ The same Docker rule as above applies BEFORE any git runs (a repository at or inside a Docker case workspace is refused), and remote sessions answer `unsupported`. ⚠️ Keep it non-interactive (`gitNonInteractiveEnv()`: `GIT_TERMINAL_PROMPT=0` + BatchMode ssh) or a fetch hangs on an invisible login prompt, but that BatchMode ssh is a DEFAULT, never an override: `fetchEnvFor` must not overwrite the repository's `core.sshCommand`, the user's own `GIT_SSH_COMMAND` or a `GIT_SSH` (`readRepoSshCommand` reads it inside the same limiter slot and the same wall-clock bound as the fetch it serves, and the spawn gets only what the read left), and `StrictHostKeyChecking=accept-new` writes an unknown host key into `~/.ssh/known_hosts` without asking: BatchMode stops a prompt, not a write. Keep it bounded: `MAX_REPOS`/`MAX_REPOS_LIMIT` (12/50), `MAX_FETCH_OUTPUT_BYTES` (2 MB), the git timeout per spawn, and `FETCH_CONCURRENCY` (4) as ONE `Limiter` shared by the fetches of the whole tick: `createLimiter` keeps its count in the closure, so a limiter that delegated to `mapLimited` per call bounds each call, and 4 folders × 4 repositories would start 16 git processes. ⚠️ One semaphore cannot bound both the folders and the fetches: a folder holding a slot would then wait for a slot its own fetch needs, so the tick bounds its folders with `mapLimited` and hands the shared bound to every run. ⚠️ Failure text reaching a client is control-stripped and credential-redacted (`sanitizeGitOutput`) and the browser writes it with `textContent`. Scheduler semantics: settings are read fresh each tick (`GIT_FETCH_TICK_INTERVAL_MS`, 15 s), a per-session override wins even while the app-wide switch is off, the interval is timed from the run START, state is keyed by FOLDER (sessions sharing one folder are the same clone, so one run serves them all, the schedule is stamped at selection, and every session on a folder is remembered, a folder is due when ANY session open on it is due, so the order the sessions were read cannot decide which interval wins (both orders are tested), and the folder is probed once for the whole group rather than once per session on it: closing the one that holds the override must not stop the folder's fetching while another session is still open on it), a tick is skipped while the previous one is still going, and a user-chosen folder is probed BOUNDED with the default options before anything runs (rule #516: `unknown` is never read as `absent`). ⚠️ The two settings (`gitFetchEnabled`, `gitFetchIntervalSeconds`, off/300 by default, clamped 30–3600) are **synced**, not per-device: they must stay out of `displayKeys` and out of the strip destructure in settings-ui.js, or the scheduler reads nobody's value. Per-session state rides `SessionUpdated` (no new SSE event) as `gitFetch`, and the click route publishes the run's trigger, not the request's: `trigger: 'click'` only when the click was the run, because a click that joined a tick already going fetched nothing and cannot report itselLine truncated

docs/wiki/Git-Worktrees.md

@@ -39,6 +39,19 @@ name.
 
 **Open** on a worktree's row starts another session in it, with the CLI chosen above.
 
+## When an agent moves into a worktree
+
+Claude Code can move a running session into a worktree part way through (its EnterWorktree tool),
+and the session's tab stays on the case. While the session's pane is in a worktree inside the
+session's folder, the **Files** panel lists that worktree, so you see the files the agent is
+editing. A strip under the panel's title names the worktree, and its **Session folder** button
+switches to the session's own folder (**Back to worktree** returns). The panel follows the agent
+in and back out on its own while it is open.
+
+A worktree outside the session's folder (`git worktree add ../feature`) is not followed: Codeman
+only serves files inside the session's folder. Open such a worktree as a case of its own with
+Add Case > Link Existing.
+
 ## Removing one
 
 Two ways, and both use `git worktree remove` **without** `--force`:

docs/wiki/Working-With-Files.md

@@ -6,8 +6,9 @@ until you get home.
 
 ## The File Viewer
 
-A panel that browses the active session's working directory. Its header button is on by
-default; if it is missing, re-enable it in **App Settings → Header & Panels**.
+A panel that browses the active session's working directory, or the git worktree its agent
+moved into ([Git Worktrees](Git-Worktrees#when-an-agent-moves-into-a-worktree)). Its header
+button is on by default; if it is missing, re-enable it in **App Settings → Header & Panels**.
 
 It renders what it can:
 

package-lock.json

@@ -63,7 +63,7 @@
         "exceljs": "4.4.0",
         "fflate": "0.8.3",
         "pixelmatch": "^6.0.0",
-        "playwright": "^1.58.0",
+        "playwright": "^1.64.1",
         "pngjs": "^7.0.0",
         "postcss": "^8.5.15",
         "prettier": "^3.4.0",
@@ -9736,50 +9736,32 @@
       }
     },
     "node_modules/playwright": {
-      "version": "1.60.0",
-      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.60.0.tgz",
-      "integrity": "sha512-hheHdokM8cdqCb0lcE3s+zT4t4W+vvjpGxsZlDnikarzx8tSzMebh3UiFtgqwFwnTnjYQcsyMF8ei2mCO/tpeA==",
+      "version": "1.64.1",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.64.1.tgz",
+      "integrity": "sha512-HCrVhHr5QQuwYoswEUGTb7gGp522yflbv/ST8nF4sFWGuLjQCt17Q/EubpGGSNKYn1tsTCPZxqHhHCfVURu7UA==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
-        "playwright-core": "1.60.0"
+        "playwright-core": "1.64.1"
       },
       "bin": {
         "playwright": "cli.js"
       },
       "engines": {
-        "node": ">=18"
-      },
-      "optionalDependencies": {
-        "fsevents": "2.3.2"
+        "node": ">=20"
       }
     },
     "node_modules/playwright-core": {
-      "version": "1.60.0",
-      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.60.0.tgz",
-      "integrity": "sha512-9bW6zvX/m0lEbgTKJ6YppOKx8H3VOPBMOCFh2irXFOT4BbHgrx5hPjwJYLT40Lu+4qtD36qKc/Hn56StUW57IA==",
+      "version": "1.64.1",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.64.1.tgz",
+      "integrity": "sha512-BC4s8y6SEVA6Q1rSxZTto8hI1KUI3xXlHGZgvGqP4IqPdI/a6FX9H29IDNz7vKo9l21b6LfYosScPL6M3xxyDQ==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {
         "playwright-core": "cli.js"
       },
       "engines": {
-        "node": ">=18"
-      }
-    },
-    "node_modules/playwright/node_modules/fsevents": {
-      "version": "2.3.2",
-      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
-      "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
-      "dev": true,
-      "hasInstallScript": true,
-      "license": "MIT",
-      "optional": true,
-      "os": [
-        "darwin"
-      ],
-      "engines": {
-        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
+        "node": ">=20"
       }
     },
     "node_modules/pngjs": {

package.json

@@ -133,7 +133,7 @@
     "exceljs": "4.4.0",
     "fflate": "0.8.3",
     "pixelmatch": "^6.0.0",
-    "playwright": "^1.58.0",
+    "playwright": "^1.64.1",
     "pngjs": "^7.0.0",
     "postcss": "^8.5.15",
     "prettier": "^3.4.0",

src/live-worktree.ts

@@ -0,0 +1,94 @@
+/**
+ * @fileoverview Which linked git worktree a session's pane is in.
+ *
+ * Claude Code's worktree feature moves the running `claude` process into
+ * `<repo>/.claude/worktrees/<name>` part way through a session. `Session.workingDir` is the
+ * session's identity and stays on the main checkout, so the Files panel kept listing a tree the
+ * agent had left (#765). `Session.paneCwd` does follow: tmux reads the process cwd, measured with
+ * Claude Code 2.1.318 going into a worktree on EnterWorktree and back on ExitWorktree. It also
+ * follows every `cd` in a shell session, so it cannot be the panel's root by itself. This module
+ * answers the narrower question: is the pane inside a linked worktree, and which one.
+ *
+ * A linked worktree is recognised by its `.git` FILE (`gitdir: <repo>/.git/worktrees/<id>`) rather
+ * than by running `git worktree list`: this runs from the pane watcher whenever a directory
+ * changes, and a file read starts no process, no repository config and no filter.
+ *
+ * Only a folder at or below `workingDir` is ever an answer, and that is the whole security
+ * argument: the file routes already serve everything under `workingDir`, so following a pane
+ * there widens nothing, and a planted `.git` file can only move where the listing STARTS inside
+ * that same folder. A worktree outside it (`git worktree add ../feature`) stays unfollowed, since
+ * listing it would need a second confinement root. Nothing here is a confinement decision: the
+ * routes keep judging every path against `workingDir`.
+ *
+ * Probes are bounded (#516). The folder can sit on a mount that stopped answering, and an
+ * `unknown` answer stops the walk rather than being read as "no `.git` here".
+ *
+ * @module live-worktree
+ */
+
+import { promises as fs } from 'node:fs';
+import { basename, dirname, join } from 'node:path';
+import { probePathKind } from './utils/bounded-path-probe.js';
+
+/** A linked worktree a session's pane is in. */
+export interface LiveWorktree {
+  /** The worktree folder's name, for display. */
+  name: string;
+  /** Absolute path, spelled like the session's `workingDir`. */
+  path: string;
+}
+
+/** More than any real `.git` file. It is read only to recognise the first line. */
+const MAX_DOT_GIT_FILE_BYTES = 4096;
+
+/**
+ * Whether the text of a `.git` file names a linked worktree's git dir
+ * (`<common dir>/worktrees/<id>`), as opposed to a submodule's (`<common dir>/modules/<name>`).
+ * The path may be relative: `git worktree add --relative-paths` writes it that way.
+ */
+export function isLinkedWorktreeGitFile(text: string): boolean {
+  const gitDir = /^gitdir:[ \t]*(.+?)[ \t]*$/m.exec(text)?.[1];
+  if (!gitDir) return false;
+  const segments = gitDir.split('/').filter(Boolean);
+  return segments.length >= 2 && segments[segments.length - 2] === 'worktrees';
+}
+
+/** What `<dir>/.git` says: a linked worktree's root, a boundary the walk must stop at, or nothing. */
+async function classifyDotGit(dir: string): Promise<'worktree' | 'stop' | 'none'> {
+  const dotGit = join(dir, '.git');
+  const kind = await probePathKind(dotGit);
+  if (kind === 'absent') return 'none';
+  // A `.git` directory is a repository of its own, and `unknown` is never read as absent.
+  if (kind !== 'file') return 'stop';
+  let handle: fs.FileHandle | undefined;
+  try {
+    // lstat, so a `.git` that is a symlink or a FIFO is refused before anything opens it:
+    // opening a FIFO waits for a writer and would hold a threadpool worker for good.
+    if (!(await fs.lstat(dotGit)).isFile()) return 'stop';
+    handle = await fs.open(dotGit, 'r');
+    const { buffer, bytesRead } = await handle.read(Buffer.alloc(MAX_DOT_GIT_FILE_BYTES), 0, MAX_DOT_GIT_FILE_BYTES, 0);
+    return isLinkedWorktreeGitFile(buffer.toString('utf8', 0, bytesRead)) ? 'worktree' : 'stop';
+  } catch {
+    return 'stop';
+  } finally {
+    await handle?.close().catch(() => {});
+  }
+}
+
+/**
+ * The linked worktree strictly below `workingDir` that holds `cwd`, if any. Walks up from `cwd`
+ * and stops at `workingDir`, at a repository or submodule of its own, or at anything it cannot
+ * read. `workingDir` itself is never an answer: a session started in a worktree is already
+ * listing it. Never throws.
+ */
+export async function findLiveWorktree(workingDir: string, cwd: string | undefined): Promise<LiveWorktree | undefined> {
+  if (!cwd?.startsWith('/')) return undefined;
+  const root = workingDir.length > 1 ? workingDir.replace(/\/+$/, '') : workingDir;
+  const under = root === '/' ? '/' : `${root}/`;
+  for (let dir = cwd; dir !== root && dir.startsWith(under); dir = dirname(dir)) {
+    const found = await classifyDotGit(dir);
+    if (found === 'worktree') return { name: basename(dir), path: dir };
+    if (found === 'stop') return undefined;
+  }
+  return undefined;
+}

src/session.ts

@@ -73,6 +73,7 @@ import type { GitFetchStatus } from './git-fetch.js';
 import { resolveAndClaimOmpSessionId } from './utils/omp-session-resolver.js';
 import { claudeTranscriptExists } from './utils/claude-transcript.js';
 import { probePathKind } from './utils/bounded-path-probe.js';
+import type { LiveWorktree } from './live-worktree.js';
 import { PATH_PROBE_TIMEOUT_MS, WORKSPACE_REALPATH_RETRY_MS } from './config/path-probe.js';
 import { matchesPattern } from './config/cli-registry/patterns.js';
 import { probeDockerCliVersion } from './docker-hosts.js';
@@ -766,6 +767,8 @@ export class Session extends EventEmitter {
    * serialized by toState() but never restored by the constructor.
    */
   private _paneCwd: string | undefined;
+  /** See {@link liveWorktree}. */
+  private _liveWorktree: LiveWorktree | undefined;
   /**
    * `workingDir` with symlinks resolved, so a pane reading (tmux reads the
    * process cwd, always the resolved path) can be put back into `workingDir`'s
@@ -1576,6 +1579,22 @@ export class Session extends EventEmitter {
     return true;
   }
 
+  /**
+   * The linked git worktree inside `workingDir` that {@link paneCwd} is in, when there is one
+   * (`live-worktree.ts`). The Files panel lists it instead of the main checkout. Runtime-only and
+   * never a confinement root, like `paneCwd`: it is always a folder the file routes already serve.
+   */
+  get liveWorktree(): LiveWorktree | undefined {
+    return this._liveWorktree;
+  }
+
+  /** Record the result of a worktree lookup. Returns whether it CHANGED, so the caller broadcasts only then. */
+  setLiveWorktree(next: LiveWorktree | undefined): boolean {
+    if (next?.path === this._liveWorktree?.path) return false;
+    this._liveWorktree = next;
+    return true;
+  }
+
   /** `workingDir` without a trailing separator (the root stays `/`). */
   private _workspaceSpelling(): string {
     return this.workingDir.length > 1 ? this.workingDir.replace(/\/+$/, '') : this.workingDir;
@@ -2300,6 +2319,7 @@ export class Session extends EventEmitter {
       status: this._status,
       workingDir: this.workingDir,
       paneCwd: this._paneCwd,
+      liveWorktree: this._liveWorktree,
       remote: this._remote,
       docker: this._docker,
       owner: this._owner,

src/types/session.ts

@@ -34,6 +34,7 @@
 import type { RespawnConfig } from './respawn.js';
 import type { AttachmentDetectedType } from './tools.js';
 import type { GitFetchStatus } from '../git-fetch.js';
+import type { LiveWorktree } from '../live-worktree.js';
 
 /** Status of a Claude session */
 export type SessionStatus = 'idle' | 'busy' | 'stopped' | 'error';
@@ -847,6 +848,15 @@ export interface SessionState {
    * routes like any other out-of-workspace path.
    */
   paneCwd?: string;
+  /**
+   * The linked git worktree inside `workingDir` that the pane is in NOW, when there is one:
+   * Claude Code's `.claude/worktrees/<name>`, or any other worktree of the repository under
+   * the session's folder. Derived from {@link paneCwd} by `live-worktree.ts`, so it is
+   * runtime-only and absent wherever `paneCwd` is, and absent for a worktree outside
+   * `workingDir`: the file routes never serve those. NOT a confinement root; the Files panel
+   * only starts its listing here.
+   */
+  liveWorktree?: LiveWorktree;
   /** Remote execution metadata, present when this session runs over SSH through local tmux */
   remote?: SessionRemote;
   /** Docker execution metadata, present when this session runs inside a container via local tmux + docker exec */

src/web/public/app.js

@@ -2458,6 +2458,8 @@ class CodemanApp {
     }
     // cliMouseTracking (Claude's fullscreen mode) ends a keyboard row hold.
     if (session.id === this.activeSessionId) this._reconcileKeyboardHold?.();
+    // The agent moved into or out of a git worktree while the Files panel is open (#765).
+    if (session.id === this.activeSessionId) this._followFileBrowserWorktree?.(session);
     // Update parentSessionName for any subagents belonging to this session
     // (fixes stale name display after session rename)
     this.updateSubagentParentNames(session.id);

src/web/public/i18n.js

@@ -1133,6 +1133,9 @@
     'Filter by date range': '按日期范围筛选',
     'Filter by session status': '按会话状态筛选',
     'Filter files...': '筛选文件…',
+    Worktree: '工作树',
+    'Session folder': '会话文件夹',
+    'Back to worktree': '返回工作树',
     'Any status': '任意状态',
     'Any time': '任意时间',
     'Last hour': '最近一小时',

src/web/public/index.html

@@ -617,6 +617,11 @@
           <button class="btn-icon-sm" onclick="app.closeFileBrowserPanel()" title="Close">&times;</button>
         </div>
       </div>
+      <div class="file-browser-root" id="fileBrowserRoot" hidden>
+        <span class="file-browser-root-label" id="fileBrowserRootLabel"></span>
+        <span class="file-browser-root-name" id="fileBrowserRootName" data-i18n-skip></span>
+        <button type="button" class="file-browser-root-switch" id="fileBrowserRootSwitch" onclick="app.toggleFileBrowserRoot()"></button>
+      </div>
       <div class="file-browser-search">
         <input type="text" id="fileBrowserSearch" placeholder="Filter files..." oninput="app.filterFileBrowser(this.value)">
       </div>

src/web/public/panels-ui.js

@@ -3282,6 +3282,8 @@ Object.assign(CodemanApp.prototype, {
         matches: [],
         deferredDirectoryTarget: null,
         filter: typeof this.fileBrowserFilter === 'string' ? this.fileBrowserFilter : '',
+        // The person asked for the session folder while the agent is in a worktree (#765).
+        sessionRootPinned: false,
       };
     }
     return this._fileBrowserState;
@@ -3304,6 +3306,7 @@ Object.assign(CodemanApp.prototype, {
     state.deferredDirectoryTarget = null;
     state.filter = '';
     state.view = 'normal';
+    state.sessionRootPinned = false;
     this.fileBrowserData = null;
     this.fileBrowserFilter = '';
     this.fileBrowserExpandedDirs?.clear?.();
@@ -3314,6 +3317,7 @@ Object.assign(CodemanApp.prototype, {
     this._syncFileBrowserExpandBtn();
     const expandBtn = this.$?.('fileBrowserExpandBtn');
     if (expandBtn) expandBtn.innerHTML = '\u229E';
+    this._renderFileBrowserRoot(null);
 
     const panel = this.$?.('fileBrowserPanel');
     const treeEl = this.$?.('fileBrowserTree');
@@ -3346,6 +3350,7 @@ Object.assign(CodemanApp.prototype, {
     state.deferredDirectoryTarget = null;
     state.filter = '';
     state.view = 'normal';
+    state.sessionRootPinned = false;
     this.fileBrowserData = null;
     this.fileBrowserFilter = '';
     this.fileBrowserExpandedDirs?.clear?.();
@@ -3356,6 +3361,7 @@ Object.assign(CodemanApp.prototype, {
     this._syncFileBrowserExpandBtn();
     const expandBtn = this.$?.('fileBrowserExpandBtn');
     if (expandBtn) expandBtn.innerHTML = '\u229E';
+    this._renderFileBrowserRoot(null);
     const treeEl = this.$?.('fileBrowserTree');
     if (treeEl) treeEl.innerHTML = '';
     const statusEl = this.$?.('fileBrowserStatus');
@@ -3448,6 +3454,60 @@ Object.assign(CodemanApp.prototype, {
     this._syncFileBrowserExpandBtn();
     this.renderFileBrowserTree(normalState.sessionId);
     this._renderFileBrowserNormalStatus(normalState.data, normalState.showHidden);
+    this._renderFileBrowserRoot(normalState.data);
+  },
+
+  // The strip under the panel header, present only while the session's pane is in a linked
+  // worktree (#765): it says which of the two folders is listed and switches between them.
+  // Everything here comes from GET .../files, so the strip describes the tree on screen rather
+  // than the session's state a moment later.
+  _renderFileBrowserRoot(data) {
+    const strip = this.$?.('fileBrowserRoot');
+    if (!strip) return;
+    const worktree = data?.worktree;
+    if (typeof worktree?.path !== 'string' || typeof worktree?.name !== 'string') {
+      strip.hidden = true;
+      return;
+    }
+    const inWorktree = data.root === worktree.path;
+    const label = this.$?.('fileBrowserRootLabel');
+    const name = this.$?.('fileBrowserRootName');
+    const button = this.$?.('fileBrowserRootSwitch');
+    if (label) label.textContent = inWorktree ? 'Worktree' : 'Session folder';
+    if (name) name.textContent = inWorktree ? worktree.name : '';
+    if (button) button.textContent = inWorktree ? 'Session folder' : 'Back to worktree';
+    strip.title = typeof data.root === 'string' ? data.root : '';
+    strip.hidden = false;
+  },
+
+  // The `root` parameter of a listing or search. The server ignores it while the pane is not in
+  // a worktree, so the panel always asks unless the person chose the session folder.
+  _fileBrowserRootParam() {
+    return this._ensureFileBrowserState().sessionRootPinned ? '' : '&root=live';
+  },
+
+  toggleFileBrowserRoot() {
+    const state = this._ensureFileBrowserState();
+    state.sessionRootPinned = !state.sessionRootPinned;
+    return this._reloadFileBrowserKeepingQuery();
+  },
+
+  // Called on every session update of the active session. Compares with what the listing on
+  // screen reported rather than with the previous update, so a load already in flight when the
+  // pane moved is corrected by the next update, and an answer that matches ends it: a listing
+  // always reports the session's worktree, whichever folder it walked, so this cannot loop.
+  _followFileBrowserWorktree(session) {
+    const state = this._fileBrowserState;
+    if (!state || state.ownerSessionId !== session.id) return;
+    if (this.$?.('fileBrowserPanel')?.classList.contains('visible') !== true) return;
+    const normal = state.normalState;
+    if (normal?.phase !== 'ready' || normal.sessionId !== session.id) return;
+    const live = session.liveWorktree?.path ?? null;
+    const listed = normal.data?.worktree?.path ?? null;
+    if (live === listed) return;
+    // The pin was about the worktree the agent has just left.
+    state.sessionRootPinned = false;
+    this._reloadFileBrowserKeepingQuery();
   },
 
   _validateFileBrowserTreeEnvelope(result) {
@@ -3552,14 +3612,20 @@ Object.assign(CodemanApp.prototype, {
   },
 
   async toggleFileBrowserHidden() {
-    const state = this._ensureFileBrowserState();
-    const rawInput = typeof state.filter === 'string' ? state.filter : '';
-    const query = rawInput.trim();
     this.fileBrowserShowHidden = !this.fileBrowserShowHidden;
     try {
       localStorage.setItem(FILE_BROWSER_SHOW_HIDDEN_KEY, this.fileBrowserShowHidden ? '1' : '0');
     } catch {}
     this._syncFileBrowserHiddenBtn();
+    return this._reloadFileBrowserKeepingQuery();
+  },
+
+  // Re-fetch the tree after something the server filters on changed (hidden files, the listing's
+  // root), then re-run the search in the box against the new tree.
+  async _reloadFileBrowserKeepingQuery() {
+    const state = this._ensureFileBrowserState();
+    const rawInput = typeof state.filter === 'string' ? state.filter : '';
+    const query = rawInput.trim();
 
     if (state.inFlight?.timer !== undefined && state.inFlight?.timer !== null) {
       clearTimeout(state.inFlight.timer);
@@ -3633,7 +3699,7 @@ Object.assign(CodemanApp.prototype, {
     const request = (async () => {
       try {
         const res = await fetch(
-          `/api/sessions/${encodeURIComponent(sessionId)}/files?depth=5&showHidden=${showHidden}`,
+          `/api/sessions/${encodeURIComponent(sessionId)}/files?depth=5&showHidden=${showHidden}${this._fileBrowserRootParam()}`,
         );
         if (!res.ok) throw new Error('Failed to load files');
         const result = await res.json();
@@ -3820,6 +3886,7 @@ Object.assign(CodemanApp.prototype, {
       showHidden: this.fileBrowserShowHidden === true,
       rawInput,
       query,
+      rootParam: this._fileBrowserRootParam(),
       timer: null,
     };
     state.view = 'search-pending';
@@ -3834,7 +3901,7 @@ Object.assign(CodemanApp.prototype, {
       request.timer = null;
       try {
         const res = await fetch(
-          `/api/sessions/${encodeURIComponent(ownerSessionId)}/files?depth=5&showHidden=${request.showHidden}&q=${encodeURIComponent(query)}`,
+          `/api/sessions/${encodeURIComponent(ownerSessionId)}/files?depth=5&showHidden=${request.showHidden}&q=${encodeURIComponent(query)}${request.rootParam}`,
         );
         if (!res.ok) throw new Error('Search failed');
         const result = await res.json();

src/web/public/styles.css

@@ -12207,6 +12207,45 @@ html:is([data-skin="paper-gray"], [data-skin="solarized-light"], [data-skin="cat
   background: var(--bg-hover);
 }
 
+.file-browser-root {
+  display: flex;
+  align-items: center;
+  gap: 0.4rem;
+  padding: 0.25rem 0.5rem;
+  border-bottom: 1px solid var(--border);
+  font-size: 0.7rem;
+  color: var(--text-dim);
+}
+
+.file-browser-root[hidden] {
+  display: none;
+}
+
+.file-browser-root-name {
+  flex: 1 1 auto;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  color: var(--text);
+}
+
+.file-browser-root-switch {
+  flex: 0 0 auto;
+  padding: 0.1rem 0.4rem;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: transparent;
+  color: inherit;
+  font: inherit;
+  cursor: pointer;
+}
+
+.file-browser-root-switch:hover {
+  color: var(--text);
+  border-color: var(--text-dim);
+}
+
 .file-browser-search {
   padding: 0.4rem;
   border-bottom: 1px solid var(--border);

src/web/routes/file-routes.ts

@@ -1595,12 +1595,27 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
   // File tree listing
   app.get('/api/sessions/:id/files', async (req) => {
     const { id } = req.params as { id: string };
-    const { depth, showHidden, q } = req.query as { depth?: string; showHidden?: string; q?: string };
+    const { depth, showHidden, q, root } = req.query as {
+      depth?: string;
+      showHidden?: string;
+      q?: string;
+      root?: string;
+    };
     const session = findSessionOrFail(ctx, id, req);
 
     const maxDepth = Math.min(parseInt(depth || '5', 10), 10);
     const includeHidden = showHidden === 'true';
     const workingDir = session.workingDir;
+    // `root=live` starts the walk at the linked worktree the pane is in (#765). That folder is
+    // inside `workingDir` (`live-worktree.ts`), and every `path` below stays relative to
+    // `workingDir`, so file-content, file-raw and the edit route need nothing new and judge these
+    // paths against the same root as any other. Only the search predicate reads a path relative
+    // to the listing, since that is the tree the person is looking at.
+    const liveWorktree = session.liveWorktree;
+    const walkRoot =
+      root === 'live' && liveWorktree && (await probePathKind(liveWorktree.path, { pastCap: true })) === 'directory'
+        ? liveWorktree.path
+        : workingDir;
     // null for an empty/whitespace query, which is what keeps the default
     // tree response byte-identical when no search is requested.
     const matcher = compileFileQuery(q ?? '');
@@ -1676,17 +1691,18 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
 
           const fullPath = join(dirPath, entry.name);
           const relativePath = relative(workingDir, fullPath);
+          const listedPath = relative(walkRoot, fullPath);
 
           if (entry.isDirectory()) {
             totalDirectories++;
-            if (matcher(entry.name, relativePath)) {
+            if (matcher(entry.name, listedPath)) {
               matches.push({ name: entry.name, path: relativePath, type: 'directory' });
             }
             // Always recurse, even when this directory does not match.
             await searchDirectory(fullPath, currentDepth + 1);
           } else {
             totalFiles++;
-            if (matcher(entry.name, relativePath)) {
+            if (matcher(entry.name, listedPath)) {
               let size: number | undefined;
               try {
                 size = (await fs.stat(fullPath)).size;
@@ -1705,12 +1721,13 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
         }
       };
 
-      await searchDirectory(workingDir, 1);
+      await searchDirectory(walkRoot, 1);
 
       return {
         success: true,
         data: {
-          root: workingDir,
+          root: walkRoot,
+          ...(liveWorktree && { worktree: liveWorktree }),
           tree: [],
           matches,
           totalFiles,
@@ -1791,12 +1808,13 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
       }
     };
 
-    const tree = await scanDirectory(workingDir, 1);
+    const tree = await scanDirectory(walkRoot, 1);
 
     return {
       success: true,
       data: {
-        root: workingDir,
+        root: walkRoot,
+        ...(liveWorktree && { worktree: liveWorktree }),
         tree,
         totalFiles,
         totalDirectories,

src/web/server.ts

@@ -35,6 +35,7 @@ import fastifyWebsocket from '@fastify/websocket';
 import fastifyMultipart from '@fastify/multipart';
 import { pasteImageDirInUseByOtherSession, startPasteImageGc, uploadDirs } from './paste-image-gc.js';
 import { CLEAN_EXIT_CLOSE_REASON, shouldCloseCleanlyExitedSession } from '../pane-exit-sweep.js';
+import { findLiveWorktree } from '../live-worktree.js';
 import { join, dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { existsSync, mkdirSync, readFileSync, chmodSync, statSync } from 'node:fs';
@@ -2967,6 +2968,7 @@ export class WebServer extends EventEmitter {
       // `undefined` here means an authoritative read listed no single directory
       // for the session (split into several panes, or gone from the socket).
       const paneCwdChanged = getPaneCurrentPath ? session.setPaneCwd(getPaneCurrentPath(muxName)) : false;
+      if (paneCwdChanged) void this.refreshLiveWorktree(session);
       if (session.setPaneExit(getPaneExit(muxName))) {
         this.persistSessionState(session);
       } else if (!paneCwdChanged) {
@@ -2977,6 +2979,18 @@ export class WebServer extends EventEmitter {
     this.closeCleanlyExitedSessions();
   }
 
+  /**
+   * Work out which linked worktree a session's pane moved into (#765). In the background, since
+   * it reads the folder, and only after the directory changed, so an idle pane costs nothing.
+   * A reading newer than the one this lookup started from owns the answer.
+   */
+  private async refreshLiveWorktree(session: Session): Promise<void> {
+    const cwd = session.paneCwd;
+    const worktree = await findLiveWorktree(session.workingDir, cwd);
+    if (session.paneCwd !== cwd) return;
+    if (session.setLiveWorktree(worktree)) this.broadcastSessionStateDebounced(session.id);
+  }
+
   /**
    * Close every session whose agent exited cleanly, through the same
    * `cleanupSession()` the X button uses (Ark0N/Codeman#446). A pinned session

test/edit-history-sync.test.ts

@@ -428,14 +428,20 @@ describe('EditHistorySync', () => {
     host.append('main', editLine('t1', T0, '/w/a.ts'));
     const orig = host.read;
     let first = true;
+    let inRead!: () => void;
+    const reachedRead = new Promise<void>((r) => (inRead = r));
     host.read = async (...a) => {
       if (first) {
         first = false;
+        inRead();
         await gate;
       }
       return orig(...a);
     };
     const slow = sync.sync(local);
+    // Only once s1 holds the gate: the sessions load their stores independently, so a later one
+    // could reach the read first, take the gate and hang the loop below before `release()`.
+    await reachedRead;
     for (let i = 1; i <= MAX_LOADED_STORES + 1; i++) await sync.sync({ ...local, id: `s1-${i}` });
     release();
     expect(await slow).toEqual({ state: 'ok' });

test/file-browser-search.test.ts

@@ -387,7 +387,7 @@ describe('File Viewer server search', () => {
 
     await vi.advanceTimersByTimeAsync(1);
     expect(pending).toHaveLength(1);
-    expect(pending[0].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=false&q=src%20%26%20docs');
+    expect(pending[0].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=false&q=src%20%26%20docs&root=live');
   });
 
   it('is a safe no-op without a panel or session and can lazily adopt a later active owner', async () => {
@@ -399,7 +399,7 @@ describe('File Viewer server search', () => {
     app.activeSessionId = 'session/B';
     app.filterFileBrowser('after-session');
     await vi.advanceTimersByTimeAsync(250);
-    expect(pending[0].url).toBe('/api/sessions/session%2FB/files?depth=5&showHidden=false&q=after-session');
+    expect(pending[0].url).toBe('/api/sessions/session%2FB/files?depth=5&showHidden=false&q=after-session&root=live');
 
     pending[0].reply.resolve(response(successfulData()));
     await vi.advanceTimersByTimeAsync(0);
@@ -450,7 +450,7 @@ describe('File Viewer server search', () => {
     expect(pending).toHaveLength(0);
     await vi.advanceTimersByTimeAsync(1);
     expect(pending.map(({ url }) => url)).toEqual([
-      '/api/sessions/session%2FA/files?depth=5&showHidden=false&q=second%20query',
+      '/api/sessions/session%2FA/files?depth=5&showHidden=false&q=second%20query&root=live',
     ]);
   });
 
@@ -659,7 +659,7 @@ describe('File Viewer server search', () => {
     await vi.advanceTimersByTimeAsync(250);
 
     expect(pending).toHaveLength(1);
-    expect(pending[0].url.endsWith(`&q=${'x'.repeat(256)}`)).toBe(true);
+    expect(pending[0].url.endsWith(`&q=${'x'.repeat(256)}&root=live`)).toBe(true);
   });
 
   it('rejects 257 trimmed characters without a request', async () => {
@@ -786,7 +786,7 @@ describe('File Viewer server search', () => {
       expect(elements.fileBrowserTree.innerHTML).toContain('Loading files');
       expect(elements.fileBrowserTree.innerHTML).not.toContain('old-result.ts');
       expect(elements.fileBrowserTree.innerHTML).not.toContain('old-preference.ts');
-      expect(pending[1].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=true');
+      expect(pending[1].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=true&root=live');
 
       pending[1].reply.resolve(response(successfulTree('new-preference.ts')));
       await toggle;
@@ -794,7 +794,7 @@ describe('File Viewer server search', () => {
       expect(app._fileBrowserState.view).toBe('search-pending');
       expect(elements.fileBrowserTree.innerHTML).toContain('Searching');
       await vi.advanceTimersByTimeAsync(250);
-      expect(pending[2].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=true&q=widget');
+      expect(pending[2].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=true&q=widget&root=live');
       pending[2].reply.resolve(
         response(
           successfulData({
@@ -877,8 +877,8 @@ describe('File Viewer server search', () => {
       const firstToggle = app.toggleFileBrowserHidden();
       const secondToggle = app.toggleFileBrowserHidden();
       expect(pending.slice(1).map(({ url }) => url)).toEqual([
-        '/api/sessions/session%2FA/files?depth=5&showHidden=true',
-        '/api/sessions/session%2FA/files?depth=5&showHidden=false',
+        '/api/sessions/session%2FA/files?depth=5&showHidden=true&root=live',
+        '/api/sessions/session%2FA/files?depth=5&showHidden=false&root=live',
       ]);
 
       pending[1].reply.resolve(response(successfulTree('stale-hidden.ts')));
@@ -891,7 +891,7 @@ describe('File Viewer server search', () => {
       await vi.advanceTimersByTimeAsync(250);
 
       expect(pending).toHaveLength(4);
-      expect(pending[3].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=false&q=widget');
+      expect(pending[3].url).toBe('/api/sessions/session%2FA/files?depth=5&showHidden=false&q=widget&root=live');
       expect(app.fileBrowserShowHidden).toBe(false);
     });
 
@@ -1674,7 +1674,7 @@ describe('File Viewer server search', () => {
       expect(immediateState.activeSessionId).toBe('session/B');
       expect(immediateState.ownerSessionId).toBe('session/B');
       expect(immediateState.resizeCalls).toBe(1);
-      expect(immediateState.fileUrls).toEqual(['/api/sessions/session%2FB/files?depth=5&showHidden=false']);
+      expect(immediateState.fileUrls).toEqual(['/api/sessions/session%2FB/files?depth=5&showHidden=false&root=live']);
 
       expect(filePending).toHaveLength(1);
       expect(app._fileBrowserState.ownerSessionId).toBe('session/B');
@@ -1755,7 +1755,7 @@ describe('File Viewer server search', () => {
       expect(elements.fileBrowserExpandBtn.innerHTML).toBe('\u229E');
       expect(elements.fileBrowserTree.querySelectorAll('.file-tree-item')).toHaveLength(0);
       expect(elements.fileBrowserTree.innerHTML).toContain('Loading files');
-      expect(pending.map(({ url }) => url)).toEqual(['/api/sessions/session%2FB/files?depth=5&showHidden=false']);
+      expect(pending.map(({ url }) => url)).toEqual(['/api/sessions/session%2FB/files?depth=5&showHidden=false&root=live']);
 
       await vi.advanceTimersByTimeAsync(250);
       expect(pending).toHaveLength(1);
@@ -1797,8 +1797,8 @@ describe('File Viewer server search', () => {
       await vi.advanceTimersByTimeAsync(250);
 
       expect(pending.map(({ url }) => url)).toEqual([
-        '/api/sessions/session%2FB/files?depth=5&showHidden=false',
-        '/api/sessions/session%2FB/files?depth=5&showHidden=false&q=during%20load',
+        '/api/sessions/session%2FB/files?depth=5&showHidden=false&root=live',
+        '/api/sessions/session%2FB/files?depth=5&showHidden=false&q=during%20load&root=live',
       ]);
       expect(pending.every(({ url }) => !url.includes('session%2FA'))).toBe(true);
     });
@@ -1815,9 +1815,9 @@ describe('File Viewer server search', () => {
 
       expect(secondA).not.toBe(firstA);
       expect(pending.map(({ url }) => url)).toEqual([
-        '/api/sessions/session%2FA/files?depth=5&showHidden=false',
-        '/api/sessions/session%2FB/files?depth=5&showHidden=false',
-        '/api/sessions/session%2FA/files?depth=5&showHidden=false',
+        '/api/sessions/session%2FA/files?depth=5&showHidden=false&root=live',
+        '/api/sessions/session%2FB/files?depth=5&showHidden=false&root=live',
+        '/api/sessions/session%2FA/files?depth=5&showHidden=false&root=live',
       ]);
 
       pending[0].reply.resolve(response(successfulTree('stale-A.ts')));

test/file-browser-worktree.test.ts

@@ -0,0 +1,227 @@
+/**
+ * @fileoverview Files panel following the agent into a git worktree (#765).
+ *
+ * The server does the walking, so what can go wrong here is the client: asking for the wrong root,
+ * showing a strip that does not describe the tree on screen, or reloading forever. The last one is
+ * why the follow compares with what the listing reported rather than with the previous update.
+ *
+ * Loaded via `vm` with a stubbed context, like file-browser-hidden.test.ts.
+ */
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import vm from 'node:vm';
+import { describe, expect, it, vi } from 'vitest';
+
+const PUBLIC = resolve(import.meta.dirname, '../src/web/public');
+const panelsJs = readFileSync(resolve(PUBLIC, 'panels-ui.js'), 'utf8');
+const appJs = readFileSync(resolve(PUBLIC, 'app.js'), 'utf8');
+const indexHtml = readFileSync(resolve(PUBLIC, 'index.html'), 'utf8');
+const stylesCss = readFileSync(resolve(PUBLIC, 'styles.css'), 'utf8');
+
+const WORKTREE = { name: 'probe', path: '/repo/.claude/worktrees/probe' };
+
+function element() {
+  const classes = new Set<string>();
+  return {
+    innerHTML: '',
+    textContent: '',
+    title: '',
+    hidden: true,
+    value: '',
+    classList: {
+      toggle: (name: string, on: boolean) => (on ? classes.add(name) : classes.delete(name)),
+      contains: (name: string) => classes.has(name),
+    },
+    setAttribute: () => {},
+    querySelectorAll: () => [],
+  };
+}
+
+function loadPanel() {
+  const CodemanApp = function CodemanApp(this: unknown) {} as unknown as new () => Record<string, any>;
+  const context = vm.createContext({
+    CodemanApp,
+    console,
+    localStorage: { getItem: () => null, setItem: () => {}, removeItem: () => {} },
+    escapeHtml: (s: string) => String(s),
+    document: { getElementById: () => null, addEventListener: vi.fn() },
+    window: { addEventListener: vi.fn() },
+    setTimeout,
+    clearTimeout,
+    fetch: undefined as unknown,
+    CodemanBase: { url: (p: string) => p },
+  });
+  vm.runInContext(panelsJs, context, { filename: 'panels-ui.js' });
+
+  const ids = [
+    'fileBrowserPanel',
+    'fileBrowserTree',
+    'fileBrowserStatus',
+    'fileBrowserHiddenBtn',
+    'fileBrowserSearch',
+    'fileBrowserRoot',
+    'fileBrowserRootLabel',
+    'fileBrowserRootName',
+    'fileBrowserRootSwitch',
+  ];
+  const elements = Object.fromEntries(ids.map((id) => [id, element()]));
+  elements.fileBrowserPanel.classList.toggle('visible', true);
+
+  const app = new CodemanApp();
+  app.$ = (id: string) => elements[id] ?? null;
+  app.activeSessionId = 'sess-1';
+  app.fileBrowserData = null;
+  app.fileBrowserExpandedDirs = new Set<string>();
+  app.fileBrowserFilter = '';
+  app.fileBrowserShowHidden = false;
+  app.getFileIcon = () => '';
+  app.formatFileSize = () => '';
+
+  // A stand-in for the route: the session's worktree, listed when the request asks for it.
+  const server = { worktree: null as typeof WORKTREE | null, requests: [] as string[] };
+  context.fetch = async (url: string) => {
+    server.requests.push(url);
+    const live = url.includes('root=live') && server.worktree;
+    const data = {
+      root: live ? server.worktree!.path : '/repo',
+      ...(server.worktree && { worktree: server.worktree }),
+      tree: [],
+      totalFiles: 0,
+      totalDirectories: 0,
+      truncated: false,
+      ...(url.includes('q=') && { mode: 'search', matches: [], matchCount: 0 }),
+    };
+    return { ok: true, json: async () => ({ success: true, data }) };
+  };
+  return { app, elements, server };
+}
+
+const strip = (elements: Record<string, ReturnType<typeof element>>) => ({
+  hidden: elements.fileBrowserRoot.hidden,
+  label: elements.fileBrowserRootLabel.textContent,
+  name: elements.fileBrowserRootName.textContent,
+  button: elements.fileBrowserRootSwitch.textContent,
+  title: elements.fileBrowserRoot.title,
+});
+
+describe('Files panel in a git worktree', () => {
+  it('asks for the live root by default', async () => {
+    const { app, server } = loadPanel();
+    await app.loadFileBrowser('sess-1');
+    expect(server.requests[0]).toContain('root=live');
+  });
+
+  it('shows no strip for a session in no worktree', async () => {
+    const { app, elements } = loadPanel();
+    await app.loadFileBrowser('sess-1');
+    expect(elements.fileBrowserRoot.hidden).toBe(true);
+  });
+
+  it('says which worktree is listed, and offers the session folder', async () => {
+    const { app, elements, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+    expect(strip(elements)).toEqual({
+      hidden: false,
+      label: 'Worktree',
+      name: 'probe',
+      button: 'Session folder',
+      title: WORKTREE.path,
+    });
+  });
+
+  it('switches to the session folder and back', async () => {
+    const { app, elements, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+
+    await app.toggleFileBrowserRoot();
+    expect(server.requests[1]).not.toContain('root=live');
+    expect(strip(elements)).toEqual({
+      hidden: false,
+      label: 'Session folder',
+      name: '',
+      button: 'Back to worktree',
+      title: '/repo',
+    });
+
+    await app.toggleFileBrowserRoot();
+    expect(server.requests[2]).toContain('root=live');
+    expect(elements.fileBrowserRootName.textContent).toBe('probe');
+  });
+
+  it('keeps the query in the box across the switch, and searches the new root', async () => {
+    const { app, elements, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+    app._fileBrowserState.filter = 'main';
+    elements.fileBrowserSearch.value = 'main';
+
+    await app.toggleFileBrowserRoot();
+    await vi.waitFor(() => expect(server.requests.some((url) => url.includes('q=main'))).toBe(true));
+
+    const search = server.requests.find((url) => url.includes('q=main'))!;
+    expect(search).not.toContain('root=live');
+  });
+
+  it('follows the agent into a worktree while the panel is open', async () => {
+    const { app, elements, server } = loadPanel();
+    await app.loadFileBrowser('sess-1');
+    expect(server.requests).toHaveLength(1);
+
+    server.worktree = WORKTREE;
+    app._followFileBrowserWorktree({ id: 'sess-1', liveWorktree: WORKTREE });
+    await vi.waitFor(() => expect(server.requests).toHaveLength(2));
+    await vi.waitFor(() => expect(elements.fileBrowserRoot.hidden).toBe(false));
+    expect(elements.fileBrowserRootName.textContent).toBe('probe');
+  });
+
+  it('follows the agent back out, and a pin on the old worktree does not outlive it', async () => {
+    const { app, elements, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+    await app.toggleFileBrowserRoot();
+
+    server.worktree = null;
+    app._followFileBrowserWorktree({ id: 'sess-1' });
+    await vi.waitFor(() => expect(elements.fileBrowserRoot.hidden).toBe(true));
+    expect(app._fileBrowserState.sessionRootPinned).toBe(false);
+  });
+
+  it('settles: updates that agree with the listing reload nothing', async () => {
+    const { app, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+    app._followFileBrowserWorktree({ id: 'sess-1', liveWorktree: WORKTREE });
+    app._followFileBrowserWorktree({ id: 'sess-1', liveWorktree: WORKTREE });
+    expect(server.requests).toHaveLength(1);
+  });
+
+  it('leaves another session and a closed panel alone', async () => {
+    const { app, elements, server } = loadPanel();
+    await app.loadFileBrowser('sess-1');
+    app._followFileBrowserWorktree({ id: 'other', liveWorktree: WORKTREE });
+    elements.fileBrowserPanel.classList.toggle('visible', false);
+    app._followFileBrowserWorktree({ id: 'sess-1', liveWorktree: WORKTREE });
+    expect(server.requests).toHaveLength(1);
+  });
+
+  it('drops the pin and the strip on a session switch', async () => {
+    const { app, elements, server } = loadPanel();
+    server.worktree = WORKTREE;
+    await app.loadFileBrowser('sess-1');
+    await app.toggleFileBrowserRoot();
+
+    app._activateFileBrowserSession('sess-2');
+    expect(app._fileBrowserState.sessionRootPinned).toBe(false);
+    expect(elements.fileBrowserRoot.hidden).toBe(true);
+  });
+
+  it('is wired up in the page', () => {
+    expect(appJs).toContain('this._followFileBrowserWorktree?.(session)');
+    expect(indexHtml).toContain('id="fileBrowserRoot" hidden');
+    expect(indexHtml).toContain('onclick="app.toggleFileBrowserRoot()"');
+    // The strip sets `display`, so `hidden` needs its own rule or it never hides.
+    expect(stylesCss).toMatch(/\.file-browser-root\[hidden\]\s*\{\s*display: none;/);
+  });
+});

test/live-worktree.test.ts

@@ -0,0 +1,125 @@
+/**
+ * @fileoverview `findLiveWorktree()` (#765): which linked worktree a session's pane is in.
+ *
+ * The answer moves the Files panel's listing, so what matters is what it must NOT answer: the
+ * session folder itself, a folder outside it, a plain subfolder (a `cd` in a shell must not re-root
+ * the panel), a repository or submodule nested in the folder, and a `.git` that is not a regular
+ * file. Runs against a real filesystem, and one case against a worktree real git made.
+ */
+import { execFileSync } from 'node:child_process';
+import { mkdirSync, mkdtempSync, rmSync, symlinkSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { findLiveWorktree, isLinkedWorktreeGitFile } from '../src/live-worktree.js';
+
+describe('isLinkedWorktreeGitFile', () => {
+  it('accepts what git writes for a linked worktree, absolute or relative', () => {
+    expect(isLinkedWorktreeGitFile('gitdir: /home/me/repo/.git/worktrees/probe\n')).toBe(true);
+    expect(isLinkedWorktreeGitFile('gitdir: ../../../.git/worktrees/probe\n')).toBe(true);
+  });
+
+  it('refuses a submodule, a bare path and text that is not a gitdir line', () => {
+    expect(isLinkedWorktreeGitFile('gitdir: ../.git/modules/lib\n')).toBe(false);
+    expect(isLinkedWorktreeGitFile('gitdir: worktrees\n')).toBe(false);
+    expect(isLinkedWorktreeGitFile('/home/me/repo/.git/worktrees/probe\n')).toBe(false);
+    expect(isLinkedWorktreeGitFile('')).toBe(false);
+  });
+});
+
+describe('findLiveWorktree', () => {
+  let base: string;
+  let repo: string;
+  let worktree: string;
+
+  beforeEach(() => {
+    base = mkdtempSync(join(tmpdir(), 'live-worktree-'));
+    repo = join(base, 'repo');
+    worktree = join(repo, '.claude', 'worktrees', 'probe');
+    mkdirSync(join(repo, '.git'), { recursive: true });
+    mkdirSync(join(worktree, 'src', 'deep'), { recursive: true });
+    writeFileSync(join(worktree, '.git'), `gitdir: ${repo}/.git/worktrees/probe\n`);
+  });
+
+  afterEach(() => {
+    rmSync(base, { recursive: true, force: true });
+  });
+
+  it('finds the worktree from its own root and from below it', async () => {
+    const expected = { name: 'probe', path: worktree };
+    expect(await findLiveWorktree(repo, worktree)).toEqual(expected);
+    expect(await findLiveWorktree(repo, join(worktree, 'src', 'deep'))).toEqual(expected);
+  });
+
+  it('answers the same for a workingDir spelled with a trailing slash', async () => {
+    expect(await findLiveWorktree(`${repo}/`, worktree)).toEqual({ name: 'probe', path: worktree });
+  });
+
+  it('does not treat the session folder as a worktree of itself', async () => {
+    writeFileSync(join(worktree, 'marker'), '');
+    expect(await findLiveWorktree(worktree, worktree)).toBeUndefined();
+    expect(await findLiveWorktree(worktree, join(worktree, 'src'))).toBeUndefined();
+  });
+
+  it('stays on the session folder for a plain subfolder, so a shell cd moves nothing', async () => {
+    mkdirSync(join(repo, 'src'));
+    expect(await findLiveWorktree(repo, repo)).toBeUndefined();
+    expect(await findLiveWorktree(repo, join(repo, 'src'))).toBeUndefined();
+  });
+
+  it('never answers outside the session folder', async () => {
+    const outside = join(base, 'repo-feature');
+    mkdirSync(outside);
+    writeFileSync(join(outside, '.git'), `gitdir: ${repo}/.git/worktrees/feature\n`);
+    // A sibling sharing the folder's name as a prefix is the case a bare startsWith gets wrong.
+    expect(await findLiveWorktree(repo, outside)).toBeUndefined();
+    expect(await findLiveWorktree(repo, '/')).toBeUndefined();
+  });
+
+  it('stops at a submodule and at a repository of its own', async () => {
+    const submodule = join(repo, 'lib');
+    mkdirSync(submodule);
+    writeFileSync(join(submodule, '.git'), 'gitdir: ../.git/modules/lib\n');
+    expect(await findLiveWorktree(repo, submodule)).toBeUndefined();
+
+    const nested = join(worktree, 'vendored');
+    mkdirSync(join(nested, '.git'), { recursive: true });
+    expect(await findLiveWorktree(repo, nested)).toBeUndefined();
+  });
+
+  it('refuses a .git that is not a regular file', async () => {
+    const linked = join(repo, 'linked');
+    mkdirSync(linked);
+    symlinkSync(join(worktree, '.git'), join(linked, '.git'));
+    expect(await findLiveWorktree(repo, linked)).toBeUndefined();
+
+    // A FIFO would block open() for good: the test would time out rather than fail.
+    const piped = join(repo, 'piped');
+    mkdirSync(piped);
+    execFileSync('mkfifo', [join(piped, '.git')]);
+    expect(await findLiveWorktree(repo, piped)).toBeUndefined();
+  });
+
+  it('answers nothing without an absolute reading', async () => {
+    expect(await findLiveWorktree(repo, undefined)).toBeUndefined();
+    expect(await findLiveWorktree(repo, '')).toBeUndefined();
+    expect(await findLiveWorktree(repo, '.claude/worktrees/probe')).toBeUndefined();
+  });
+
+  it('recognises a worktree real git made', async () => {
+    const real = join(base, 'real');
+    const git = (...args: string[]) =>
+      execFileSync('git', ['-c', 'user.name=t', '-c', 'user.email=t@example.com', ...args], {
+        cwd: real,
+        stdio: 'ignore',
+      });
+    mkdirSync(real);
+    git('init', '-q');
+    git('commit', '-q', '--allow-empty', '-m', 'init');
+    git('worktree', 'add', '-q', '.claude/worktrees/made', '-b', 'worktree-made');
+    expect(await findLiveWorktree(real, join(real, '.claude', 'worktrees', 'made'))).toEqual({
+      name: 'made',
+      path: join(real, '.claude', 'worktrees', 'made'),
+    });
+  });
+});

test/pane-cwd-tracking.test.ts

@@ -29,11 +29,11 @@
  *
  * Port: ephemeral
  */
-import { mkdirSync, mkdtempSync, readFileSync, realpathSync, rmSync, symlinkSync } from 'node:fs';
+import { mkdirSync, mkdtempSync, readFileSync, realpathSync, rmSync, symlinkSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join, resolve } from 'node:path';
 import vm from 'node:vm';
-import { afterEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { Session, rebasePath } from '../src/session.js';
 import { WebServer } from '../src/web/server.js';
 import type { SessionDocker, SessionRemote } from '../src/types.js';
@@ -278,6 +278,77 @@ describe('a pane read reaching the session record', () => {
     expect(session.toState().workingDir).toBe('/work/proj');
   });
 
+  describe('liveWorktree (#765)', () => {
+    let base: string;
+    let repo: string;
+    let worktree: string;
+
+    beforeEach(() => {
+      base = mkdtempSync(join(tmpdir(), 'pane-live-worktree-'));
+      repo = join(base, 'repo');
+      worktree = join(repo, '.claude', 'worktrees', 'probe');
+      mkdirSync(worktree, { recursive: true });
+      writeFileSync(join(worktree, '.git'), `gitdir: ${repo}/.git/worktrees/probe\n`);
+    });
+
+    afterEach(() => {
+      rmSync(base, { recursive: true, force: true });
+    });
+
+    const inRepo = () => {
+      const { mux, sessions, web } = build();
+      const session = localMuxSession({ workingDir: repo });
+      sessions.set(session.id, session);
+      const broadcast = vi.fn();
+      (web as unknown as { broadcastSessionStateDebounced: (id: string) => void }).broadcastSessionStateDebounced =
+        broadcast;
+      mux.getPaneExit = () => undefined;
+      return { mux, session, web, broadcast };
+    };
+
+    it('publishes the worktree the pane moved into, and clears it when the pane leaves', async () => {
+      const { mux, session, web, broadcast } = inRepo();
+      let dir = worktree;
+      mux.getPaneCurrentPath = () => dir;
+      mux.emit('paneExitsUpdated');
+      await vi.waitFor(() => expect(session.liveWorktree).toEqual({ name: 'probe', path: worktree }));
+      // What the browser receives, and what the file routes read: never the confinement root.
+      const state = (
+        web as unknown as { getSessionStateWithRespawn: (s: Session) => { liveWorktree?: unknown } }
+      ).getSessionStateWithRespawn(session);
+      expect(state.liveWorktree).toEqual({ name: 'probe', path: worktree });
+      expect(session.toState().workingDir).toBe(repo);
+
+      const broadcasts = broadcast.mock.calls.length;
+      dir = repo;
+      mux.emit('paneExitsUpdated');
+      await vi.waitFor(() => expect(session.liveWorktree).toBeUndefined());
+      expect(broadcast.mock.calls.length).toBeGreaterThan(broadcasts);
+    });
+
+    it('does nothing for a pane that has not moved', async () => {
+      const { mux, session } = inRepo();
+      mux.getPaneCurrentPath = () => repo;
+      const lookup = vi.spyOn(session, 'setLiveWorktree');
+      mux.emit('paneExitsUpdated');
+      await vi.waitFor(() => expect(lookup).toHaveBeenCalledTimes(1));
+      mux.emit('paneExitsUpdated');
+      await new Promise((resolve) => setTimeout(resolve, 20));
+      expect(lookup).toHaveBeenCalledTimes(1);
+    });
+
+    it('drops an answer for a directory the pane has already left', async () => {
+      const { web, session } = inRepo();
+      session.setPaneCwd(worktree);
+      const refresh = (
+        web as unknown as { refreshLiveWorktree: (s: Session) => Promise<void> }
+      ).refreshLiveWorktree.call(web, session);
+      session.setPaneCwd(repo);
+      await refresh;
+      expect(session.liveWorktree).toBeUndefined();
+    });
+  });
+
   it('broadcasts a directory change once, and nothing on an unchanged tick', () => {
     const { mux, sessions } = build();
     const session = localMuxSession();

test/routes/file-routes-live-worktree.test.ts

@@ -0,0 +1,105 @@
+/**
+ * @fileoverview `GET /api/sessions/:id/files?root=live` (#765).
+ *
+ * The listing starts at the worktree the pane is in, and every `path` stays relative to
+ * `workingDir`: that is what keeps the preview, raw and edit routes working unchanged, inside the
+ * same confinement. Real filesystem on purpose, since the walk is the thing under test.
+ */
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { createRouteTestHarness, type RouteTestHarness } from './_route-test-utils.js';
+import { registerFileRoutes } from '../../src/web/routes/file-routes.js';
+
+const PREFIX = '.claude/worktrees/probe';
+
+describe('Files panel listing of a live worktree', () => {
+  let harness: RouteTestHarness;
+  let repo: string;
+  let worktree: string;
+
+  const list = async (query = '') => {
+    const res = await harness.app.inject({
+      method: 'GET',
+      url: `/api/sessions/${harness.ctx._sessionId}/files?depth=5${query}`,
+    });
+    expect(res.statusCode).toBe(200);
+    return res.json().data;
+  };
+  const names = (nodes: Array<{ name: string }>) => nodes.map((node) => node.name);
+
+  beforeEach(async () => {
+    harness = await createRouteTestHarness(registerFileRoutes);
+    repo = mkdtempSync(join(homedir(), 'live-worktree-route-'));
+    worktree = join(repo, PREFIX);
+    mkdirSync(join(repo, 'src'), { recursive: true });
+    mkdirSync(join(worktree, 'src'), { recursive: true });
+    writeFileSync(join(repo, 'src', 'main-only.ts'), 'main');
+    writeFileSync(join(worktree, 'src', 'worktree-only.ts'), 'worktree');
+    Object.assign(harness.ctx._session, {
+      workingDir: repo,
+      liveWorktree: { name: 'probe', path: worktree },
+    });
+  });
+
+  afterEach(async () => {
+    await harness.app.close();
+    rmSync(repo, { recursive: true, force: true });
+  });
+
+  it('lists the worktree with paths relative to the session folder', async () => {
+    const data = await list('&root=live');
+    expect(data.root).toBe(worktree);
+    expect(data.worktree).toEqual({ name: 'probe', path: worktree });
+    expect(names(data.tree)).toEqual(['src']);
+    expect(data.tree[0].path).toBe(`${PREFIX}/src`);
+    expect(data.tree[0].children[0].path).toBe(`${PREFIX}/src/worktree-only.ts`);
+  });
+
+  it('does not need hidden files on, though the worktree lives under a dot folder', async () => {
+    const data = await list('&root=live&showHidden=false');
+    expect(data.totalFiles).toBe(1);
+  });
+
+  it('keeps the session folder without the parameter, and still reports the worktree', async () => {
+    const data = await list();
+    expect(data.root).toBe(repo);
+    expect(data.worktree).toEqual({ name: 'probe', path: worktree });
+    expect(names(data.tree)).toEqual(['src']);
+    expect(data.tree[0].children[0].path).toBe('src/main-only.ts');
+  });
+
+  it('answers exactly as before for a session in no worktree', async () => {
+    Object.assign(harness.ctx._session, { liveWorktree: undefined });
+    const data = await list('&root=live');
+    expect(data).toEqual(await list());
+    expect(data.root).toBe(repo);
+    expect('worktree' in data).toBe(false);
+  });
+
+  it('falls back to the session folder when the worktree has gone, keeping the report', async () => {
+    rmSync(worktree, { recursive: true });
+    const data = await list('&root=live');
+    expect(data.root).toBe(repo);
+    // Kept so the panel's comparison with the session's state settles instead of reloading forever.
+    expect(data.worktree).toEqual({ name: 'probe', path: worktree });
+  });
+
+  it('searches the worktree: the query reads paths in the listing, the result in the session folder', async () => {
+    const data = await list(`&root=live&q=${encodeURIComponent('src/*.ts')}`);
+    expect(data.root).toBe(worktree);
+    expect(data.matches.map((match: { path: string }) => match.path)).toEqual([`${PREFIX}/src/worktree-only.ts`]);
+    expect(data.worktree).toEqual({ name: 'probe', path: worktree });
+  });
+
+  it('serves a listed path through the unchanged preview route', async () => {
+    const path = `${PREFIX}/src/worktree-only.ts`;
+    const res = await harness.app.inject({
+      method: 'GET',
+      url: `/api/sessions/${harness.ctx._sessionId}/file-content?path=${encodeURIComponent(path)}`,
+    });
+    expect(res.json().success).toBe(true);
+    expect(res.json().data.content).toBe('worktree');
+  });
+});