feat(channels): add the flag-gated spaces layout (3/4)

apps/code/snapshots.yml

@@ -72,30 +72,6 @@ snapshots:
         hash: v1.k4693efd2.1d199b2c4bba8034cb18fb5b49866b64a6eb3311591add5f58ec288710dce2e9.FCc9egSaO1Onih417yciSYKNROe8zqDZyyS6xuXCZGw
     billing-usagemeter--zero-spend-limit--light:
         hash: v1.k4693efd2.b50c18736bbde45fc89f4c0ac7fd616286e5c1ecc2a56910fffca13eaa13d8a2.31z4F0JmvMeR4yqk5pjs_OQ3MypnM2miZI9al4wuc8c
-    channels-taskfeedrow--agent-origin--dark:
-        hash: v1.k4693efd2.82f8c70a399c9ea768201933e202fcc2fde74332c5153aeabf6835ace79beee6.-SVboDRIZ_-nh4PtMliCv7e7iCtdUm-1m2xQ9Xzcdfw
-    channels-taskfeedrow--agent-origin--light:
-        hash: v1.k4693efd2.4c1db3470d5ec9b4db9872d0e048314d0078979e8fbdb602b8c648ba70d7209f._KPUvj46p33u7A4Xndz-git-4rp7VKca1MpeTztlB6w
-    channels-taskfeedrow--human-email-only--dark:
-        hash: v1.k4693efd2.0f4dece4643b7375b77746347658f4fe65b37817cdfa9ad1ba697067e619f428.f0jKZ4OYqsmeJjXffjt-amK9cwE81JF0lgSMqtn37PA
-    channels-taskfeedrow--human-email-only--light:
-        hash: v1.k4693efd2.14db0510f7ea5c57985cf0cb60ab08f5e146c7243eeb1b0b963f74e85c7d60f4.ijHQLK0lZjjUlOQuzYzisImU9DWsNmZM7i5GYfWU4E0
-    channels-taskfeedrow--human-started--dark:
-        hash: v1.k4693efd2.e0abdae2e8ac2ef29793ea7afc2a2580c6610e07a3c640ad782af7fd3c12592a.YUgF_BTPzZoqnWXvyLBRs3w9C_P3Yfh4-cP4mUqs2NQ
-    channels-taskfeedrow--human-started--light:
-        hash: v1.k4693efd2.84c26deb1a587fe061238b3982b555167575893bacc9cd2667d4d3f74646261f.abqc0Voe6FIQFflzDJTv1KewcZ4XxcDz1a0mFlJu7oM
-    channels-taskfeedrow--long-prompt--dark:
-        hash: v1.k4693efd2.876d34660bc267af79d39a971a681ba279a870061dba10b905412112c2a5e4dd.rSw1X068udMs8Arglu_WgX5RL8WZlpAc8_kVONPQhF4
-    channels-taskfeedrow--long-prompt--light:
-        hash: v1.k4693efd2.d0d6e4b6bfa257c3f46d991777f72c345437b0be2ee16a182fa925d3ece7dc9e.6PGeOlMxVauJSQia0FAIirzaYio79-I7H4x-9LvEUbw
-    channels-taskfeedrow--no-prompt--dark:
-        hash: v1.k4693efd2.9fa967f1a9acdeba0c50a9e45ae649f118ee26938037dbefd1bb0577067b03d4.va1lGsscqLW86-5yCKc3H6pQ8Az7_HBItkgGTnTQiYU
-    channels-taskfeedrow--no-prompt--light:
-        hash: v1.k4693efd2.a02339aecdb6fc327fdf6586e28ceeebf8490442fe217eb8bb46f1ce66bff78a.2l7XdvdW3D0GlLmPwDdTFgjZWdav68bZX_LYResVKwo
-    channels-taskfeedrow--no-starter--dark:
-        hash: v1.k4693efd2.66fff212f14afa9dd3bc532698a042383014a0cabd4331d30eff878148e1773d.RiectZxFTqk1husLYI-UV5ko1uZ4lpbjWstE7Hy3MJE
-    channels-taskfeedrow--no-starter--light:
-        hash: v1.k4693efd2.9ee4ad64ed7d2c5c62d0cd682d903b09da643d462d49aae0858afa500e92256b.OhGj64l-o7iWtxzJo1qt0A_CU9ME0ZRr_5e455RGUJQ
     components-permissions-permissionselector--create-new-file--dark:
         hash: v1.k4693efd2.c54203a4e636b83b3d24d7ed9c4ace8659db87cd8f231d9dc2ecc03320e31646.epDm7LebiLzlp0uuZBrE-Obt_anAn0xsE8bHFnm5vos
     components-permissions-permissionselector--create-new-file--light:
@@ -708,6 +684,30 @@ snapshots:
         hash: v1.k4693efd2.cfff4c6bbb0acef1c9941b21d2f69c24b234c2c206282acf6fcada0cb2bd2386.xILjVPp8ecQmGbPjGDdhbRyi9KFPpA_1nfYF3bfjwuc
     skill-buttons-skillbuttonsmenu--default--light:
         hash: v1.k4693efd2.eb9bd49b9700641f6f3c90653447c9767c52e997afec9843e8649b90752faad3.VdxEtBwtkU3ioy2evcNbrEKxPjQ1GDUpZAQzFe-Uho4
+    spaces-taskfeedrow--agent-origin--dark:
+        hash: v1.k4693efd2.82f8c70a399c9ea768201933e202fcc2fde74332c5153aeabf6835ace79beee6.yEZq_qnKxItv5u0Ydcqa1B4VCwv8lwXUvcaFScE2XO0
+    spaces-taskfeedrow--agent-origin--light:
+        hash: v1.k4693efd2.4c1db3470d5ec9b4db9872d0e048314d0078979e8fbdb602b8c648ba70d7209f.wt_Ufkw30jHFnxEMFXE0wQG8ignuCURuUUYIvNMnJ6U
+    spaces-taskfeedrow--human-email-only--dark:
+        hash: v1.k4693efd2.611794921d5c6270a211f4a6bc3d91fd63a74a58f0c905a79271cbc7d9c73eb8.balV69yNKs9biJzweJYwpk5e1UjZ11fFersE9UMhvEU
+    spaces-taskfeedrow--human-email-only--light:
+        hash: v1.k4693efd2.961288ce410b6376bab92428ad148b881c768e9edea4821db4818d13682f50c4.79pzkpuXwARCmUS4HtZRvb2n7dM8HUZZs-ErIXX4wwg
+    spaces-taskfeedrow--human-started--dark:
+        hash: v1.k4693efd2.6e1cf0720234b1c64ba04f6f3af965d32438551771bc3680c4391bb8463b8eee.4O-iWXxbDv-L9MsuPt6KoDvK7C95R0Jj6LTYjDwwEhk
+    spaces-taskfeedrow--human-started--light:
+        hash: v1.k4693efd2.7156c1e5b2359b5f792529aa9041ad9277842d51c3423bda4f0c029c58dcef28.PF-JYrCTfHxEzFG9dnabJxDYS47wQXnxurx8Ev_LfkY
+    spaces-taskfeedrow--long-prompt--dark:
+        hash: v1.k4693efd2.00acb2487749ee5a1db2c95da8ae0e2fb2de0815d653973e60c7ceb3ff808135.pdV864kTAUM1IgcuME846VwInafp3f-WFFxxxE4H_oY
+    spaces-taskfeedrow--long-prompt--light:
+        hash: v1.k4693efd2.8a6b372abdf9c60a558c59a703f8e7c8f65fcb55fd99e6c97c6eca23e6a76781.HbZ7kfuE60F5SWucdbYLhy98POhk8MPPX2TLA_r2hz8
+    spaces-taskfeedrow--no-prompt--dark:
+        hash: v1.k4693efd2.ff77770c9b5c656b213c139270322defa38306d714abeee6b5fe4e17e2056f88.KnYgUDb_jYEfH5aSoJbt1cwyJXAfDo_eKmIfn0fxjjc
+    spaces-taskfeedrow--no-prompt--light:
+        hash: v1.k4693efd2.d3d755ee7ea6eccbed93ea18e6dcbccbd9f77f019f5c153cb0278131b08c324f.l_KwHWHFTzODefftPGtlWsXLFi6tbH78ZRQeeY7X4Z0
+    spaces-taskfeedrow--no-starter--dark:
+        hash: v1.k4693efd2.66fff212f14afa9dd3bc532698a042383014a0cabd4331d30eff878148e1773d.-FvbS5RpndI7QXNTpQhbQShDktPrOV_jdcWDY4MUYF4
+    spaces-taskfeedrow--no-starter--light:
+        hash: v1.k4693efd2.9ee4ad64ed7d2c5c62d0cd682d903b09da643d462d49aae0858afa500e92256b.lCc1Q5KBHSLnYp7N9k6HEBxDPjf0SblH9zDLHQ7dYo8
     task-detail-continueclisessions--importing--dark:
         hash: v1.k4693efd2.3196e21b9daa2f183c79eaf2c70a5775365dbee3f1d920c64927e20a0fadcbf9.FjHhjEX3urGbycQiDehA9JQ7H2zfyl1id9rDSVjrtoI
     task-detail-continueclisessions--importing--light:

packages/core/src/canvas/runStatus.ts

@@ -37,6 +37,17 @@ export function runStatusVariant(
   return status ? RUN_STATUS_VARIANTS[status] : "default";
 }
 
+/**
+ * Whether the run is still in flight, and so worth animating in a list. Canvases
+ * and tasks that never started carry no run to wait on, and `not_started` is a
+ * queued-but-unclaimed task rather than one doing work.
+ */
+export function isRunStatusActive(
+  status: TaskRunStatus | null | undefined,
+): boolean {
+  return status === "queued" || status === "in_progress";
+}
+
 export const RUN_STATUS_FILTER_OPTIONS: readonly {
   value: TaskRunStatus | null;
   label: string;

packages/core/src/command-center/grid.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it } from "vitest";
 import {
   BRAINROT_CELL,
   clampZoom,
+  countActiveTaskCells,
   getCellCount,
   getCellSessionId,
   getGridDimensions,
@@ -97,3 +98,34 @@ describe("getCellSessionId", () => {
     expect(getCellSessionId(2)).toBe("cc-cell-2");
   });
 });
+
+describe("countActiveTaskCells", () => {
+  const live = new Set(["task-1", "task-2"]);
+
+  it("counts only cells whose task still exists", () => {
+    expect(countActiveTaskCells(["task-1", "task-2"], live)).toBe(2);
+  });
+
+  // Cells are persisted and only pruned on archive, so a deleted task's id
+  // lingers forever — counting the array's non-empty entries would never drop.
+  it("ignores a task that has since been deleted", () => {
+    expect(countActiveTaskCells(["task-1", "deleted-task"], live)).toBe(1);
+  });
+
+  it.each([
+    { name: "empty cells", cells: [null, null] },
+    { name: "the brainrot sentinel", cells: [BRAINROT_CELL] },
+    { name: "terminal cells", cells: [makeTerminalCellValue("abc123")] },
+  ])("does not count $name", ({ cells }) => {
+    expect(countActiveTaskCells(cells, live)).toBe(0);
+  });
+
+  it("counts a mixed grid correctly", () => {
+    expect(
+      countActiveTaskCells(
+        [null, BRAINROT_CELL, "task-1", "deleted", makeTerminalCellValue("t")],
+        live,
+      ),
+    ).toBe(1);
+  });
+});

packages/core/src/command-center/grid.ts

@@ -49,6 +49,21 @@ export function getTerminalCellCwd(value: string | null): string | null {
   return colon === -1 ? null : decodeURIComponent(rest.slice(colon + 1));
 }
 
+/**
+ * How many cells hold a task that still exists.
+ *
+ * Cells are persisted and only pruned when a task is archived — deleting one
+ * leaves its id behind forever — so a count has to be taken against the live
+ * task list rather than trusting the array's length. Excludes the brainrot and
+ * terminal sentinels, which are ambient chrome rather than parked work.
+ */
+export function countActiveTaskCells(
+  cells: readonly (string | null)[],
+  liveTaskIds: ReadonlySet<string>,
+): number {
+  return cells.filter((cell) => cell != null && liveTaskIds.has(cell)).length;
+}
+
 export function getGridDimensions(preset: LayoutPreset): GridDimensions {
   const [cols, rows] = preset.split("x").map(Number);
   return { cols, rows };

packages/shared/src/analytics-events.ts

@@ -891,6 +891,8 @@ export type ChannelActionType =
   | "leave_feedback"
   | "nav_click"
   | "open_channel"
+  /** Slid the sidebar back from a channel to the channel list. */
+  | "browse_channels"
   | "collapse_channel"
   | "view_more_tasks"
   | "create"

packages/ui/src/features/browser-tabs/BrowserTabStrip.tsx

@@ -29,6 +29,7 @@ import {
   useChannelMutations,
   useChannels,
 } from "@posthog/ui/features/canvas/hooks/useChannels";
+import { useChannelsLayout } from "@posthog/ui/features/canvas/hooks/useChannelsLayout";
 import {
   useDashboard,
   useDashboards,
@@ -145,6 +146,7 @@ function isAppView(value: string): value is AppView {
 }
 
 export function BrowserTabStrip() {
+  const spacesLayout = useChannelsLayout();
   const logger = useService<RootLogger>(ROOT_LOGGER);
   const snapshot = useTabsSnapshot();
   const navigate = useNavigate();
@@ -509,7 +511,8 @@ export function BrowserTabStrip() {
           const meta = channelSectionFor(section);
           return {
             id: t.id,
-            label: meta?.label ?? channel ?? "Channel",
+            label:
+              meta?.label ?? channel ?? (spacesLayout ? "Space" : "Channel"),
             icon: <HashIcon size={14} />,
             channelName: channel,
             // No section meta → the channel's index page.
@@ -545,6 +548,7 @@ export function BrowserTabStrip() {
     params.taskId,
     routeChannelSection,
     routeAppView,
+    spacesLayout,
   ]);
 
   // Navigate to a tab, tagging the history entry with its id so the switch is

packages/ui/src/features/browser-tabs/TabShortcutFallback.test.tsx

@@ -0,0 +1,30 @@
+import { render } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+import { TabShortcutFallback } from "./TabShortcutFallback";
+
+function pressCloseTab(): KeyboardEvent {
+  const event = new KeyboardEvent("keydown", {
+    key: "w",
+    code: "KeyW",
+    metaKey: true,
+    bubbles: true,
+    cancelable: true,
+  });
+  document.dispatchEvent(event);
+  return event;
+}
+
+describe("TabShortcutFallback", () => {
+  // Without a preventDefault here the key reaches Electron's Window ▸ Close
+  // role and takes the window — and everything unsaved in it — with it.
+  it("swallows Cmd+W so the host menu never sees it", () => {
+    render(<TabShortcutFallback enabled />);
+    expect(pressCloseTab().defaultPrevented).toBe(true);
+  });
+
+  // Disabled is how the BrowserTabStrip keeps ownership where it is mounted.
+  it("leaves the key alone when disabled", () => {
+    render(<TabShortcutFallback enabled={false} />);
+    expect(pressCloseTab().defaultPrevented).toBe(false);
+  });
+});

packages/ui/src/features/browser-tabs/TabShortcutFallback.tsx

@@ -0,0 +1,26 @@
+import { SHORTCUTS } from "@posthog/ui/features/command/keyboard-shortcuts";
+import { useHotkeys } from "react-hotkeys-hook";
+
+/**
+ * Renders nothing — claims Cmd/Ctrl+W wherever BrowserTabStrip isn't mounted.
+ *
+ * The strip's own CLOSE_TAB handler preventDefaults unconditionally, because
+ * otherwise the key reaches Electron's Window ▸ Close role (`{ role:
+ * "windowMenu" }` in the host menu) and closes the window, losing everything in
+ * it. Any route that renders the app without the strip — the whole channels
+ * layout, and the settings shell either way — needs someone else to hold the key.
+ *
+ * The task view's editor panel keeps closing its own tab from
+ * usePanelKeyboardShortcuts; that handler runs too, and this one only swallows.
+ */
+export function TabShortcutFallback({ enabled }: { enabled: boolean }) {
+  useHotkeys(
+    SHORTCUTS.CLOSE_TAB,
+    (event) => {
+      event.preventDefault();
+    },
+    { enabled, enableOnFormTags: true, enableOnContentEditable: true },
+  );
+
+  return null;
+}

packages/ui/src/features/canvas/AGENTS.md

@@ -25,25 +25,44 @@ The root `AGENTS.md` architecture rules still apply.
 - **Suffix `…` on anything that opens another step.** A menu item or button whose
   click opens a follow-up surface — a dialog, a nested menu, a picker, a
   confirmation — gets a trailing ellipsis (`…`, the character, not three dots) to
-  signal it isn't the final action: `New…`, `Rename channel…`, `Delete channel…`,
+  signal it isn't the final action: `New…`, `Rename space…`, `Delete space…`,
   `Choose a template…`. A label that performs its action immediately or navigates
   straight to a destination gets **no** ellipsis (`Edit CONTEXT.md`, `Star
-  channel`). When in doubt: does clicking it ask for more input or confirmation
+  space`). When in doubt: does clicking it ask for more input or confirmation
   before anything happens? If yes, add the `…`.
 
 ## Spaces & chrome
 
-- Channels is a **top-level space** reached through the app rail (`AppNav`),
+- Spaces is a **top-level space** reached through the app rail (`AppNav`),
   gated behind `project-bluebird` and wired in `routes/__root.tsx`. The rail's
-  spaces are Code (`/code`), Inbox (`/inbox`), and Channels (`/website`).
-- The Channels space has **its own chrome**: rail + a persistent channel-list
+  spaces are Code (`/code`), Inbox (`/inbox`), and Spaces (`/website`).
+- The Spaces UI has **its own chrome**: rail + a persistent channel-list
   sidebar (`ChannelsList`, rendered in `__root`) + the `WebsiteLayout` outlet. It
   does NOT use the code `HeaderRow`/`MainSidebar`, so breadcrumbs render in
   `WebsiteLayout`'s own top bar (below).
+- Under the channels layout the sidebar is a **master/detail slider**
+  (`ChannelPanes` in `ChannelsSidebar.tsx`): the searchable channel list, and the
+  channel you're in (`ChannelSidebar`, headed by `ChannelBackRow`). Both panes
+  stay mounted — the offscreen one is `inert` — so the slide has something to
+  slide and returning to the list doesn't rebuild every row. A two-finger
+  horizontal swipe moves between them (`useChannelPaneSwipe`, wheel `deltaX`
+  accumulated per gesture and locked until the wheel goes quiet).
+- In the list, "Starred"/"Channels" are headings, not parents: under the layout
+  the rows sit at the heading's level (no indent) and the "#"/lock glyph belongs
+  to the rows. The alpha's indented tree is unchanged.
+- One `ChannelsFab` serves both panes: given a `channelId` it creates inside
+  that channel (task, canvas), and either way it can create a channel. Off the
+  layout it keeps its original two-item menu. Archived moves out of the sidebar
+  and into the account menu (`ProjectSwitcher`), beside Settings.
+- **Which pane shows is view state, not a route.** `channelPaneStore` holds it,
+  separately from the scoped channel (`currentChannelStore`): "back to channels"
+  browses the list while the route, the main pane and the scoped channel stay
+  put. Every way into a channel — a row click, a deep link, a mention, ⌘1-9 —
+  ends at `showChannelPane()`, directly or through the route effect.
 
 ## Breadcrumbs
 
-- **`WebsiteLayout` renders its own top bar.** The Channels space has no code
+- **`WebsiteLayout` renders its own top bar.** The Spaces UI has no code
   `HeaderRow`, so breadcrumbs (and the dashboard controls) are a local bar inside
   `WebsiteLayout`, not pushed through the header store.
 - **A page does not get its own crumb — its H1 is the title.** A view that

packages/ui/src/features/canvas/components/ActivityView.tsx

@@ -26,6 +26,7 @@ import { UserAvatar } from "@posthog/ui/features/auth/UserAvatar";
 import { useCurrentUser } from "@posthog/ui/features/auth/useCurrentUser";
 import { MentionText } from "@posthog/ui/features/canvas/components/MentionText";
 import { useChannels } from "@posthog/ui/features/canvas/hooks/useChannels";
+import { useChannelsLayout } from "@posthog/ui/features/canvas/hooks/useChannelsLayout";
 import { useMarkTaskActivityRead } from "@posthog/ui/features/canvas/hooks/useMarkTaskActivityRead";
 import { useTaskActivity } from "@posthog/ui/features/canvas/hooks/useTaskActivity";
 import { normalizeChannelName } from "@posthog/ui/features/canvas/hooks/useTaskChannels";
@@ -222,6 +223,7 @@ function ActivityRow({
 // in, or messaged in — newest activity first. Rows clear as they are opened, not
 // when the page is; merely landing here shouldn't dismiss what you haven't read.
 export function ActivityView() {
+  const spacesLayout = useChannelsLayout();
   const client = useOptionalAuthenticatedClient();
   const { data: currentUser } = useCurrentUser({ client });
   const {
@@ -285,7 +287,8 @@ export function ActivityView() {
               Activity
             </Text>
             <Text size="2" className="block text-muted-foreground">
-              Tasks you're involved in across channels.
+              Tasks you're involved in across{" "}
+              {spacesLayout ? "spaces" : "channels"}.
             </Text>
           </div>
           {unreadCount > 0 && (
@@ -314,8 +317,8 @@ export function ActivityView() {
                 </EmptyMedia>
                 <EmptyTitle>No activity yet</EmptyTitle>
                 <EmptyDescription>
-                  Tasks you create, get tagged in, or reply to across channels
-                  land here.
+                  Tasks you create, get tagged in, or reply to across{" "}
+                  {spacesLayout ? "spaces" : "channels"} land here.
                 </EmptyDescription>
               </EmptyHeader>
             </Empty>