feat(lanes): full-width Changes, Stage all, one-read expand-all

- The Changes panel's width control gains a full-width step (narrow →
  50/50 → 70/30 → full → closed); the console beside it is hidden with
  CSS, never unmounted.
- "Expand all folders" is one GET /api/lanes/:id/git/tree-all (one
  `git ls-files`, every level shaped like /git/tree) instead of one
  request and one git process per folder.
- Overview: a Stage all button and the staged-only commit box sit above
  the file list and stay pinned while it scrolls; the Files finder is
  pinned too.

client/src/components/lanes/LaneChangesPanel.tsx

@@ -60,8 +60,6 @@ const OVERVIEW_REFRESH_MS = 15_000;
 const CONTEXT_STEPS: readonly [number, ...number[]] = [3, 12, 40, 5000];
 
 const LAST_CONTEXT = CONTEXT_STEPS[CONTEXT_STEPS.length - 1]!;
-/** Tree reads "expand all" keeps in flight at once. */
-const TREE_CONCURRENCY = 4;
 
 type Mode = "overview" | "review" | "file" | "history" | "browse";
 
@@ -425,47 +423,18 @@ export function LaneChangesPanel({
   };
 
   const [treeBusy, setTreeBusy] = useState(false);
-  // Which lane `treeChildren` was filled for; the reset effect moves it.
-  const treeLane = useRef(laneId);
 
-  // Fetches whatever level isn't cached yet, depth-first, so "expand all"
-  // works even on a tree nothing has been opened in.
+  // "Expand all" is ONE read of the whole tree: a request per folder meant a
+  // `git ls-files` per folder, seconds of waiting on a large repo.
   const expandAllDirs = async () => {
-    // A walk is many reads long; a lane switch mid-walk must not land lane A's
-    // tree in lane B, nor start from a cache the switch has not cleared yet.
     const lane = laneId;
     setTreeBusy(true);
-    const cache = treeLane.current === lane ? { ...treeChildren } : {};
-    const toExpand = new Set(expandedDirs);
-    // Level by level, at most TREE_CONCURRENCY reads in flight: one request
-    // per folder all at once is thousands on a monorepo.
-    const visit = async (path: string, next: string[]) => {
-      let entries = cache[path];
-      if (!entries) {
-        entries = (await api.lanes.gitTree(lane, path)).entries;
-        cache[path] = entries;
-      }
-      for (const e of entries) {
-        if (!e.dir) continue;
-        toExpand.add(e.path);
-        next.push(e.path);
-      }
-    };
     try {
-      for (let level = [""]; level.length && laneNow.current === lane; ) {
-        const next: string[] = [];
-        // Workers share one iterator, so each path is taken exactly once.
-        const it = level.values();
-        await Promise.all(
-          Array.from({ length: TREE_CONCURRENCY }, async () => {
-            for (const path of it) await visit(path, next);
-          })
-        );
-        level = next;
-      }
+      const { levels } = await api.lanes.gitTreeAll(lane);
+      // A lane switch mid-read must not land lane A's tree in lane B.
       if (laneNow.current !== lane) return;
-      setTreeChildren(cache);
-      setExpandedDirs(toExpand);
+      setTreeChildren(levels);
+      setExpandedDirs(new Set(Object.keys(levels).filter(Boolean)));
     } catch (err) {
       if (laneNow.current === lane) setError(err instanceof Error ? err.message : String(err));
     } finally {
@@ -516,7 +485,6 @@ export function LaneChangesPanel({
     setSha(null);
     setRange("work");
     setTreeChildren({});
-    treeLane.current = laneId;
     setExpandedDirs(new Set());
     setTreeBusy(false);
     setBusy(false);
@@ -561,12 +529,17 @@ export function LaneChangesPanel({
   // An action that resolves after a lane switch belongs to the lane left: its
   // `load` is the pre-switch one and would take a fresh ticket and paint the
   // old lane's files here, so everything after the await is dropped.
-  const act = async (action: "stage" | "unstage" | "discard", path: string, confirm?: boolean) => {
+  const act = async (
+    action: "stage" | "unstage" | "discard",
+    path: string | string[],
+    confirm?: boolean
+  ) => {
     const lane = laneId;
     setBusy(true);
     setError(null);
     try {
-      await api.lanes.gitAction(lane, action, { paths: [path], ...(confirm ? { confirm } : {}) });
+      const paths = Array.isArray(path) ? path : [path];
+      await api.lanes.gitAction(lane, action, { paths, ...(confirm ? { confirm } : {}) });
       if (laneNow.current !== lane) return;
       setConfirmDiscard(null);
       refreshGit();
@@ -617,6 +590,8 @@ export function LaneChangesPanel({
   const files = data?.available ? data.files : [];
   const allCollapsed = files.length > 0 && files.every((f) => collapsed.has(f.path));
   const stagedCount = range === "work" ? files.filter((f) => f.staged).length : 0;
+  // What "Stage all" sends: every listed file with a change the index lacks.
+  const toStage = range === "work" ? files.filter((f) => f.untracked || f.unstaged) : [];
   const current = mode === "file" ? files.find((f) => f.path === openFile) : undefined;
 
   // The armed path left the list (committed, reverted, lane switched): disarm,
@@ -836,7 +811,9 @@ export function LaneChangesPanel({
           </ul>
         ) : mode === "browse" ? (
           <div data-testid="lane-changes-browse">
-            <div className="mb-2 flex items-center gap-1.5">
+            {/* Pinned: the finder is what you reach for after scrolling a
+                long tree, not only from its top. */}
+            <div className="sticky top-0 z-10 flex items-center gap-1.5 bg-surface-3 pb-2">
               <input
                 value={query}
                 onChange={(e) => setQuery(e.target.value)}
@@ -908,6 +885,54 @@ export function LaneChangesPanel({
           <p className="text-[11px] text-fg-muted">{t(`changes.empty.${range}`)}</p>
         ) : mode === "overview" ? (
           <>
+            {/* Commit and Stage all sit ABOVE the list and stay pinned while it
+                scrolls: on a 60-file change-set the box at the bottom was a
+                scroll away from every file you had just staged. */}
+            {(stagedCount > 0 || toStage.length > 0) && (
+              <div
+                data-testid="lane-changes-actions"
+                className="sticky top-0 z-10 mb-1.5 space-y-1.5 border-b border-border-light bg-surface-3 pb-2"
+              >
+                {stagedCount > 0 && (
+                  <div data-testid="lane-changes-commit" className="flex items-center gap-1.5">
+                    <input
+                      value={message}
+                      onChange={(e) => setMessage(e.target.value)}
+                      onKeyDown={(e) => {
+                        if (e.key === "Enter" && message.trim() && !busy) void commitStaged();
+                      }}
+                      placeholder={t("changes.commitPlaceholder")}
+                      aria-label={t("changes.commitPlaceholder")}
+                      className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 text-[11px] text-fg-primary placeholder:text-fg-muted focus:border-accent focus:outline-none"
+                    />
+                    <button
+                      type="button"
+                      disabled={busy || !message.trim()}
+                      onClick={() => void commitStaged()}
+                      className="shrink-0 rounded border border-border-light px-1.5 py-0.5 text-[11px] text-fg-secondary hover:bg-surface-2 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40"
+                    >
+                      {t("changes.commitStaged", { count: stagedCount })}
+                    </button>
+                  </div>
+                )}
+                {toStage.length > 0 && (
+                  <button
+                    type="button"
+                    disabled={busy}
+                    onClick={() =>
+                      void act(
+                        "stage",
+                        toStage.map((f) => f.path)
+                      )
+                    }
+                    className="flex items-center gap-1 rounded border border-border-light px-1.5 py-0.5 text-[11px] text-fg-secondary hover:bg-surface-2 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40"
+                  >
+                    <Plus className="h-3 w-3" />
+                    {t("changes.stageAll", { count: toStage.length })}
+                  </button>
+                )}
+              </div>
+            )}
             <ul data-testid="lane-changes-overview" className="space-y-0.5">
               {files.map((f) => (
                 <ChangeRow
@@ -922,31 +947,6 @@ export function LaneChangesPanel({
                 />
               ))}
             </ul>
-            {stagedCount > 0 && (
-              <div
-                data-testid="lane-changes-commit"
-                className="mt-2 flex items-center gap-1.5 border-t border-border-light pt-2"
-              >
-                <input
-                  value={message}
-                  onChange={(e) => setMessage(e.target.value)}
-                  onKeyDown={(e) => {
-                    if (e.key === "Enter" && message.trim() && !busy) void commitStaged();
-                  }}
-                  placeholder={t("changes.commitPlaceholder")}
-                  aria-label={t("changes.commitPlaceholder")}
-                  className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 text-[11px] text-fg-primary placeholder:text-fg-muted focus:border-accent focus:outline-none"
-                />
-                <button
-                  type="button"
-                  disabled={busy || !message.trim()}
-                  onClick={() => void commitStaged()}
-                  className="shrink-0 rounded border border-border-light px-1.5 py-0.5 text-[11px] text-fg-secondary hover:bg-surface-2 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40"
-                >
-                  {t("changes.commitStaged", { count: stagedCount })}
-                </button>
-              </div>
-            )}
           </>
         ) : mode === "file" ? (
           current || (whole && text) ? (

client/src/components/lanes/__tests__/LaneChangesPanel.test.tsx

@@ -28,6 +28,7 @@ vi.mock("../../../lib/api", () => ({
       gitFile: vi.fn(),
       gitLs: vi.fn(),
       gitTree: vi.fn(),
+      gitTreeAll: vi.fn(),
     },
   },
 }));
@@ -283,6 +284,22 @@ describe("LaneChangesPanel", () => {
     await waitFor(() => expect(api.lanes.gitLog).toHaveBeenCalledTimes(1));
   });
 
+  it("stages every file the index lacks in one call, from above the list", async () => {
+    const user = userEvent.setup();
+    render(<LaneChangesPanel laneId={7} />);
+    const list = await screen.findByTestId("lane-changes-overview");
+    const actions = screen.getByTestId("lane-changes-actions");
+    // Commit box and Stage all come BEFORE the file list.
+    expect(actions.compareDocumentPosition(list) & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
+    expect(screen.getByTestId("lane-changes-commit")).toBeInTheDocument();
+
+    await user.click(screen.getByRole("button", { name: "Stage all (2)" }));
+    // The already-staged docs/API.md is not sent again.
+    expect(api.lanes.gitAction).toHaveBeenCalledWith(7, "stage", {
+      paths: ["server/lib/git-ops.js", "notes.txt"],
+    });
+  });
+
   it("needs two clicks to discard, and only the second one reaches the server", async () => {
     const user = userEvent.setup();
     render(<LaneChangesPanel laneId={7} />);
@@ -417,8 +434,16 @@ describe("LaneChangesPanel", () => {
     expect(screen.getByText("src")).toBeInTheDocument();
   });
 
-  it("expands every folder at once, fetching whatever level wasn't cached yet", async () => {
+  it("expands every folder at once from one whole-tree read", async () => {
     const user = userEvent.setup();
+    vi.mocked(api.lanes.gitTreeAll).mockResolvedValue({
+      available: true,
+      truncated: false,
+      levels: {
+        "": [{ name: "src", path: "src", dir: true }],
+        src: [{ name: "main.ts", path: "src/main.ts", dir: false }],
+      },
+    });
     vi.mocked(api.lanes.gitTree).mockImplementation(async (_id, path) => {
       if (path === "src")
         return {
@@ -788,37 +813,29 @@ describe("LaneChangesPanel", () => {
     expect(screen.getByText("server/lib/git-ops.js")).toBe(before);
   });
 
-  it("expands all folders with at most four tree reads in flight", async () => {
+  it("expands all folders with ONE request, not one per folder", async () => {
     const user = userEvent.setup();
-    let inFlight = 0;
-    let peak = 0;
     vi.mocked(api.lanes.gitTree).mockClear();
-    vi.mocked(api.lanes.gitTree).mockImplementation(async (_id, path = "") => {
-      inFlight += 1;
-      peak = Math.max(peak, inFlight);
-      await new Promise((r) => setTimeout(r, 5));
-      inFlight -= 1;
-      const depth = path ? path.split("/").length : 0;
-      const entries =
-        depth >= 2
-          ? [{ name: "leaf.ts", path: `${path}/leaf.ts`, dir: false }]
-          : Array.from({ length: 5 }, (_, i) => ({
-              name: `d${i}`,
-              path: path ? `${path}/d${i}` : `d${i}`,
-              dir: true,
-            }));
-      return { available: true, path, entries, truncated: false };
-    });
+    vi.mocked(api.lanes.gitTreeAll)
+      .mockClear()
+      .mockResolvedValue({
+        available: true,
+        truncated: false,
+        levels: {
+          "": [{ name: "src", path: "src", dir: true }],
+          src: [{ name: "main.ts", path: "src/main.ts", dir: false }],
+        },
+      });
     render(<LaneChangesPanel laneId={7} />);
     await screen.findByTestId("lane-changes-overview");
     await user.click(screen.getByRole("button", { name: "Files" }));
-    await screen.findByText("d0");
+    await screen.findByText("src");
     await user.click(screen.getByRole("button", { name: "Expand all folders" }));
 
-    await waitFor(() => expect(screen.getAllByText("leaf.ts")).toHaveLength(25));
-    // Root + 5 + 25 folders, each fetched exactly once.
-    expect(api.lanes.gitTree).toHaveBeenCalledTimes(31);
-    expect(peak).toBeLessThanOrEqual(4);
+    expect(await screen.findByText("main.ts")).toBeInTheDocument();
+    expect(api.lanes.gitTreeAll).toHaveBeenCalledTimes(1);
+    // Only the root read the Files tab made on entry — no per-folder walk.
+    expect(api.lanes.gitTree).toHaveBeenCalledTimes(1);
   });
 
   it("does not repaint the previous lane after its git action resolves post-switch", async () => {
@@ -861,21 +878,25 @@ describe("LaneChangesPanel", () => {
     expect(screen.queryByText("server/lib/git-ops.js")).toBeNull();
   });
 
-  it("does not paint the previous lane's tree when an expand-all walk outlives a lane switch", async () => {
+  it("does not paint the previous lane's tree when an expand-all read outlives a lane switch", async () => {
     const user = userEvent.setup();
     let resolveSrc: () => void = () => {};
-    vi.mocked(api.lanes.gitTree).mockImplementation((id, path) => {
-      if (id === 7 && path === "src")
-        return new Promise(
+    vi.mocked(api.lanes.gitTreeAll).mockImplementation(
+      () =>
+        new Promise(
           (r) =>
             (resolveSrc = () =>
               r({
                 available: true,
-                path: "src",
-                entries: [{ name: "main.ts", path: "src/main.ts", dir: false }],
                 truncated: false,
+                levels: {
+                  "": [{ name: "src", path: "src", dir: true }],
+                  src: [{ name: "main.ts", path: "src/main.ts", dir: false }],
+                },
               }))
-        );
+        )
+    );
+    vi.mocked(api.lanes.gitTree).mockImplementation((id) => {
       return Promise.resolve({
         available: true,
         path: "",

client/src/i18n/locales/en/lanes.json

@@ -110,6 +110,8 @@
   "changes.size.compact": "Narrow",
   "changes.size.half": "50 / 50",
   "changes.size.wide": "70 / 30",
+  "changes.size.full": "Full width",
+  "changes.stageAll": "Stage all ({{count}})",
   "changes.stage": "Stage this file",
   "changes.title": "Changes",
   "changes.truncated": "Some changes were left out to keep this panel responsive.",

client/src/i18n/locales/vi/lanes.json

@@ -110,6 +110,8 @@
   "changes.size.compact": "Hẹp",
   "changes.size.half": "50 / 50",
   "changes.size.wide": "70 / 30",
+  "changes.size.full": "Toàn màn hình",
+  "changes.stageAll": "Stage tất cả ({{count}})",
   "changes.stage": "Đưa file này vào index",
   "changes.title": "Thay đổi",
   "changes.truncated": "Một phần thay đổi đã bị lược bớt để bảng này còn mượt.",

client/src/lib/api.ts

@@ -2462,6 +2462,16 @@ export const api = {
      * @param id The lane id.
      * @param path Repo-relative directory; "" for the repo root.
      */
+    /**
+     * GET /api/lanes/:id/git/tree-all — every level of the tracked tree in one
+     * read, keyed by directory ("" is the root), each shaped like `gitTree`'s.
+     */
+    gitTreeAll: (id: number) =>
+      request<{
+        available: boolean;
+        levels: Record<string, LaneTreeEntry[]>;
+        truncated: boolean;
+      }>(`/lanes/${id}/git/tree-all`),
     gitTree: (id: number, path = "") =>
       request<{
         available: boolean;

client/src/pages/Workspace.tsx

@@ -53,6 +53,7 @@ import {
   PanelLeftClose,
   ChevronsLeftRight,
   PanelRightClose,
+  Maximize2,
 } from "lucide-react";
 import { api } from "../lib/api";
 import type { CwdSuggestion, RunListResponse } from "../lib/api";
@@ -88,21 +89,25 @@ const CHANGES_SIZE_KEY = "agenthub.workspace.changesSize";
 /** The three widths the Changes panel cycles through, then closed. Reading a
  *  diff and watching a console want opposite amounts of room, and which one is
  *  "work" changes several times an hour — hence ONE control that steps
- *  narrow → 50/50 → 70/30 → closed, rather than a width button beside a
+ *  narrow → 50/50 → 70/30 → full → closed, rather than a width button beside a
  *  collapse button that both live in the panel's tightest corner. */
-const CHANGES_SIZES = ["compact", "half", "wide"] as const;
+const CHANGES_SIZES = ["compact", "half", "wide", "full"] as const;
 type ChangesSize = (typeof CHANGES_SIZES)[number];
 const CHANGES_WIDTH: Record<ChangesSize, string> = {
   compact: "w-[28rem] xl:w-[34rem]",
   half: "w-1/2",
   wide: "w-[70%]",
+  // The console beside it is HIDDEN, not unmounted: a live run's terminal
+  // and a half-typed prompt must survive a round trip through full width.
+  full: "w-full",
 };
 /** The icon the one resize control shows AT each size: what the next click
  *  gives you — an even split, a wider panel, then closed. */
 const CHANGES_NEXT_ICON: Record<ChangesSize, typeof Columns2> = {
   compact: Columns2,
   half: ChevronsLeftRight,
-  wide: PanelRightClose,
+  wide: Maximize2,
+  full: PanelRightClose,
 };
 
 // ── Page ──────────────────────────────────────────────────────────────
@@ -733,7 +738,9 @@ export function Workspace() {
         <div className="flex min-h-0 flex-1 gap-4">
           <section
             data-testid="lane-detail"
-            className={`flex min-h-0 min-w-0 flex-1 flex-col ${currentLane ? "card p-4" : ""}`}
+            className={`flex min-h-0 min-w-0 flex-1 flex-col ${currentLane ? "card p-4" : ""}${
+              currentLane && changesOpen && changesSize === "full" ? " hidden" : ""
+            }`}
           >
             {/* One header row, not two. The pipeline picker, the stage badges,
               the feature picker and the router select used to sit on a second

client/src/pages/__tests__/Workspace.changesPanel.test.tsx

@@ -142,7 +142,7 @@ describe("Workspace — the Changes panel's width", () => {
     }
   }
 
-  it("steps narrow → 50/50 → 70/30 → closed on one control", async () => {
+  it("steps narrow → 50/50 → 70/30 → full → closed on one control", async () => {
     await openPanel();
     const card = () => screen.getByTestId("lane-changes-card");
     expect(card().className).toContain("w-[28rem]");
@@ -153,6 +153,11 @@ describe("Workspace — the Changes panel's width", () => {
     fireEvent.click(screen.getByTestId("lane-changes-resize"));
     expect(card().className).toContain("w-[70%]");
 
+    // Full width HIDES the console beside it — hidden, still mounted.
+    fireEvent.click(screen.getByTestId("lane-changes-resize"));
+    expect(card().className).toContain("w-full");
+    expect(screen.getByTestId("lane-detail").className).toContain("hidden");
+
     // Past the widest step the panel closes — and reopens narrow, not back at
     // 70/30, which is why closing resets the width.
     fireEvent.click(screen.getByTestId("lane-changes-resize"));

docs/API.md

@@ -498,6 +498,7 @@ GET /api/lanes/:id/git/log?limit=30[&file=<path>]
 GET /api/lanes/:id/git/file?path=<path>[&rev=work|HEAD|<sha>]
 GET /api/lanes/:id/git/ls?q=<substring>
 GET /api/lanes/:id/git/tree?path=<dir>
+GET /api/lanes/:id/git/tree-all
 ```
 
 The reads behind the Changes panel's **History**, whole-file view, quick-open
@@ -532,6 +533,7 @@ and file explorer. All four are read-only and unguarded, and all four answer
 - **`/git/tree`** → `{available, path, entries:[{name, path, dir}], truncated}`
   — one directory level, tracked entries only, directories folded and listed
   first. `400 EBADPATH` for a path that escapes the lane.
+- **`/git/tree-all`** → `{available, levels: {"<dir>": [{name, path, dir}]}, truncated}` — every level of the tracked tree from ONE `git ls-files`, each level shaped and capped like `/git/tree`'s; the Files tab's **Expand all folders** is this one request instead of one per folder.
 
 #### Read a lane's own branches
 

docs/LANES.md

@@ -575,7 +575,7 @@ says more than any sentence the dashboard could write.
 
 To the right of the lane detail sits a collapsible **Changes** card (its state
 persists per viewer in `localStorage`). Its header holds **one** control, which
-steps narrow → 50/50 → 70/30 → closed (`agenthub.workspace.changesSize`
+steps narrow → 50/50 → 70/30 → full width (the console beside it is hidden, never unmounted) → closed (`agenthub.workspace.changesSize`
 alongside `agenthub.workspace.changesOpen`); the collapsed rail reopens it
 narrow. Reading a diff and watching a console want opposite amounts of room and
 which one is "work" changes several times an hour, so the width is a step, not
@@ -638,7 +638,9 @@ in every panel narrow enough to sit beside a console.
 
 **Per-file writes are the panel's, per-repo writes are the git bar's.** Staging
 one file means nothing unless a commit can take the index as it stands, so the
-overview grows a commit box the moment anything is staged — it sends
+overview grows a commit box the moment anything is staged — above the list and
+pinned while it scrolls, beside a **Stage all** that stages every listed file
+the index lacks in one call — it sends
 `only: "staged"`, never `add -A`, and it is absent with a clean index because
 there is nothing it could mean. It is the dashboard's ONLY commit: the git bar
 above it has none, so no click can sweep the rest of the tree in with `add -A`. **Discard** is the one

server/__tests__/git-diff-ops.test.js

@@ -19,6 +19,7 @@ const {
   listCommits,
   listPaths,
   listTree,
+  listTreeAll,
   parseUnifiedDiff,
   readFileAt,
 } = require("../lib/git-diff");
@@ -456,6 +457,22 @@ describe("listCommits / readFileAt / listPaths / listTree", () => {
     );
     await assert.rejects(() => listTree(LANE, { subdir: "../.." }), { code: "EBADPATH" });
   });
+
+  it("reads every level of the tree in one pass, grouped like listTree", async () => {
+    write(LANE, "src/api/x.ts", "x\n");
+    write(LANE, "src/main.ts", "m\n");
+    gc(LANE, "add", "-A");
+    gc(LANE, "commit", "-qm", "src");
+
+    const all = await listTreeAll(LANE);
+    assert.equal(all.truncated, false);
+    // Each level equals what the one-level read returns for it.
+    for (const level of ["", "src", "src/api"]) {
+      const one = await listTree(LANE, { subdir: level });
+      assert.deepEqual(all.levels[level], one.entries, level);
+    }
+    assert.deepEqual(Object.keys(all.levels).sort(), ["", "src", "src/api"]);
+  });
 });
 
 describe("runGitAction — per-file staging, discard and branches", () => {

server/lib/git-diff.js

@@ -785,12 +785,50 @@ async function listTree(dir, { subdir = "" } = {}) {
   };
 }
 
+/**
+ * Every level of the tracked tree from ONE `git ls-files`, keyed by directory
+ * path ("" is the root), each level shaped and capped exactly like
+ * `listTree`'s. "Expand all folders" used to be one request — one ls-files —
+ * per folder, which on a large repo is thousands of git processes.
+ */
+async function listTreeAll(dir) {
+  const { all, cut } = await lsFiles(dir, []);
+  const byDir = new Map();
+  const level = (d) => {
+    let l = byDir.get(d);
+    if (!l) byDir.set(d, (l = { dirs: new Set(), files: [] }));
+    return l;
+  };
+  level("");
+  for (const p of all) {
+    const parts = p.split("/");
+    for (let i = 0; i < parts.length - 1; i++) {
+      level(parts.slice(0, i).join("/")).dirs.add(parts[i]);
+    }
+    const parent = parts.slice(0, -1).join("/");
+    level(parent).files.push({ name: parts[parts.length - 1], path: p, dir: false });
+  }
+  const levels = {};
+  let truncated = cut;
+  for (const [d, { dirs, files }] of byDir) {
+    const prefix = d ? `${d}/` : "";
+    const entries = [
+      ...[...dirs].sort().map((name) => ({ name, path: `${prefix}${name}`, dir: true })),
+      ...files.sort((a, b) => a.name.localeCompare(b.name)),
+    ];
+    if (entries.length > MAX_PATHS) truncated = true;
+    levels[d] = entries.slice(0, MAX_PATHS);
+  }
+  return { levels, truncated };
+}
+
 module.exports = {
   collectChanges,
   laneStatus,
   listCommits,
   listPaths,
   listTree,
+  listTreeAll,
   parseNumstat,
   parsePorcelainZ,
   parseUnifiedDiff,

server/routes/lanes.js

@@ -41,7 +41,14 @@ const {
   resolveBase,
   slugify,
 } = require("../lib/worktree");
-const { collectChanges, listCommits, listPaths, listTree, readFileAt } = require("../lib/git-diff");
+const {
+  collectChanges,
+  listCommits,
+  listPaths,
+  listTree,
+  listTreeAll,
+  readFileAt,
+} = require("../lib/git-diff");
 const { runGitAction } = require("../lib/git-ops");
 const { withLaneLock } = require("../lib/lane-lock");
 const { checkSync, mergeSync, continueSync } = require("../lib/lane-sync");
@@ -859,6 +866,17 @@ router.get("/:id/git/ls", async (req, res) => {
   }
 });
 
+/** Every level of the tracked tree in one read, for "expand all folders". */
+router.get("/:id/git/tree-all", async (req, res) => {
+  const lane = laneOr404(req, res);
+  if (!lane) return;
+  try {
+    res.json({ available: true, ...(await listTreeAll(lane.cwd)) });
+  } catch {
+    res.json({ available: false, levels: {}, truncated: false });
+  }
+});
+
 /** One directory level of tracked files, for the file explorer. */
 router.get("/:id/git/tree", async (req, res) => {
   const lane = laneOr404(req, res);