diff --git a/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/proposal.md b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/proposal.md
new file mode 100644
index 0000000..089bd53
--- /dev/null
+++ b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/proposal.md
@@ -0,0 +1,52 @@
+# dmux-style cockpit — Phase 7: kitty window tree in the sidebar
+
+## Why
+
+The user wants the cockpit sidebar to mirror dmux's session tree:
+`<user> > <session-name> > <pane-1> · <pane-2> · ...`. Today the
+sidebar shows the agent lanes plus the dmux-style shortcut block, but
+nothing tracks the actual Kitty windows the user has open inside the
+spawned cockpit OS-window. So when they split with Ctrl+Shift+Enter
+or Ctrl+Shift+\ in Kitty, the new pane is invisible to the cockpit.
+
+Phase 7 adds a live Kitty-window tree to the sidebar — populated from
+`kitty @ ls` — so every pane (control, agent lanes, shells) is listed
+under the user/session header with a focus marker.
+
+## What changes
+
+- New `src/cockpit/kitty-tree.js`:
+  - `readKittyTree({ env, socket, runner, osWindowId })` runs
+    `kitty @ ls --to=<sock>`, parses the JSON, and returns
+    `{ user, sessionLabel, osWindowId, windows, error }`.
+  - `flattenOsWindow` extracts windows from nested `tabs[].windows[]`.
+  - `classifyWindow` heuristically tags each window as `control`,
+    `agent`, or `shell` (used by the sidebar to print short tags).
+  - `pickOsWindow` defaults to the focused entry but accepts an
+    `osWindowId` override.
+- `src/cockpit/sidebar.js` gains `renderKittyTreeRows(state, width,
+  options)` and calls it inside `renderSidebar` between the agent
+  lanes and the shortcut block. The tree renders as:
+  ```
+  deadpool
+    gitguardex
+    >  gx cockpit                                 [gx]
+       codex codex                                [cx]
+       shell-1                                    [ba]
+  ```
+- The cockpit sidebar gracefully omits the tree section when no
+  `state.kittyTree` is set, and prints `(kitty: <error>)` when the
+  reader returned a non-empty `error` field.
+
+## Impact
+
+- Reader is fully runner-injectable for unit tests (no real Kitty
+  required in CI).
+- Sidebar tests assert the new rows render only when the tree is
+  populated; legacy tests with no tree state continue to render the
+  pre-phase-7 sidebar layout.
+- Future PRs can populate `state.kittyTree` in the cockpit-control
+  refresh loop (call `readKittyTree` on every tick); this PR ships
+  the data + render plumbing only.
+- No safety-model change.
+- ASCII-only renderer.
diff --git a/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/specs/cockpit-kitty-tree/spec.md b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/specs/cockpit-kitty-tree/spec.md
new file mode 100644
index 0000000..c6f0965
--- /dev/null
+++ b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/specs/cockpit-kitty-tree/spec.md
@@ -0,0 +1,44 @@
+## ADDED Requirements
+
+### Requirement: Cockpit ships a kitty-tree reader module
+The cockpit SHALL expose a `kitty-tree` module that runs `kitty @ ls`
+against the configured remote-control socket and returns a normalized
+tree containing the current user, session label, focused OS-window id,
+and a flat list of windows with classified kinds (`control`,
+`agent`, `shell`).
+
+#### Scenario: readKittyTree parses the kitty @ ls JSON output
+- **WHEN** `readKittyTree({ env: { KITTY_LISTEN_ON, USER }, runner })`
+  is called with a runner that returns `status: 0` and the kitty
+  `@ ls` JSON payload for one OS-window with three windows
+  (`gx cockpit`, a codex agent, a bash shell)
+- **THEN** the result has `error === ''`
+- **AND** `result.user` equals the `USER` env var
+- **AND** `result.windows` has length 3 with kinds
+  `['control', 'agent', 'shell']`.
+
+#### Scenario: Missing socket falls back to an empty tree
+- **WHEN** `readKittyTree({ env: {} })` is called with no
+  `KITTY_LISTEN_ON` set
+- **THEN** the result has `windows: []` and `error` matches `/no
+  KITTY_LISTEN_ON/`.
+
+### Requirement: Sidebar renders the kitty tree above the shortcut block
+The cockpit sidebar SHALL render the kitty window tree (when present
+on `state.kittyTree`) between the agent lanes block and the dmux-style
+shortcut block. The tree SHALL list the user, the session label, and
+each window with a `>` cursor on the focused row plus a short kind
+tag (`[gx]`, `[cx]`, `[ba]`, `[sh]`).
+
+#### Scenario: Sidebar surfaces the tree when populated
+- **WHEN** `renderSidebar` is called with `state.kittyTree` populated
+  (user `deadpool`, session `gitguardex`, three windows with the
+  first focused)
+- **THEN** the rendered output contains a line `^deadpool$`
+- **AND** the focused row matches `>\s+gx cockpit`
+- **AND** every other window appears in the output with a kind tag.
+
+#### Scenario: Sidebar omits the tree when no state
+- **WHEN** `renderSidebar` is called with no `kittyTree` field on the
+  state
+- **THEN** the rendered output does NOT contain a `^deadpool$` line.
diff --git a/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/tasks.md b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/tasks.md
new file mode 100644
index 0000000..13ab11e
--- /dev/null
+++ b/openspec/changes/agent-claude-gitguardex-dmux-cockpit-phase7-kitty-tre-2026-05-05-10-00/tasks.md
@@ -0,0 +1,27 @@
+# Tasks
+
+## 1. Spec
+- [x] 1.1 Capture proposal in `proposal.md`
+- [x] 1.2 Capture spec delta in `specs/cockpit-kitty-tree/spec.md`
+
+## 2. Tests
+- [x] 2.1 Add `test/cockpit-kitty-tree.test.js` covering
+       `buildLsArgs`, `classifyWindow`, `flattenOsWindow`,
+       `pickOsWindow`, `readKittyTree` (with and without
+       `KITTY_LISTEN_ON`), and the rendered sidebar tree (with and
+       without state).
+
+## 3. Implementation
+- [x] 3.1 Add `src/cockpit/kitty-tree.js` with `readKittyTree`,
+       `flattenOsWindow`, `classifyWindow`, `pickOsWindow`,
+       `buildLsArgs`, `userLabel`, `buildSessionLabel`, and
+       `emptyTree`.
+- [x] 3.2 Add `renderKittyTreeRows` to `src/cockpit/sidebar.js` and
+       insert it into `renderSidebar` between the agent lanes block
+       and the shortcut block.
+
+## 4. Cleanup
+- [ ] 4.1 Commit changes on the agent branch.
+- [ ] 4.2 Push branch and open a PR.
+- [ ] 4.3 Run `gx branch finish ... --via-pr --wait-for-merge --cleanup`.
+- [ ] 4.4 Record PR URL and `MERGED` evidence.
diff --git a/src/cockpit/kitty-tree.js b/src/cockpit/kitty-tree.js
new file mode 100644
index 0000000..7d9dd45
--- /dev/null
+++ b/src/cockpit/kitty-tree.js
@@ -0,0 +1,144 @@
+'use strict';
+
+const cp = require('node:child_process');
+const os = require('node:os');
+const path = require('node:path');
+
+const DEFAULT_BIN = 'kitty';
+const DEFAULT_TIMEOUT_MS = 1500;
+
+function text(value, fallback = '') {
+  if (typeof value === 'string') return value.trim() || fallback;
+  if (value === null || value === undefined) return fallback;
+  return String(value).trim() || fallback;
+}
+
+function defaultRunner(cmd, args, options = {}) {
+  return cp.spawnSync(cmd, args, {
+    cwd: options.cwd,
+    env: options.env ? { ...process.env, ...options.env } : process.env,
+    encoding: 'utf8',
+    stdio: 'pipe',
+    timeout: options.timeout || DEFAULT_TIMEOUT_MS,
+  });
+}
+
+function buildLsArgs(socket) {
+  const sock = text(socket);
+  const args = ['@'];
+  if (sock) args.push(`--to=${sock}`);
+  args.push('ls');
+  return args;
+}
+
+function classifyWindow(window = {}) {
+  const title = String(window.title || '').toLowerCase();
+  const cmdline = Array.isArray(window.cmdline) ? window.cmdline.join(' ').toLowerCase() : '';
+  if (/^gx cockpit/.test(title) || /gx cockpit/.test(cmdline)) return 'control';
+  if (title.startsWith('agent ') || /agent\//.test(cmdline)) return 'agent';
+  if (title === 'terminal' || cmdline.endsWith('bash') || cmdline.endsWith('zsh') || cmdline.endsWith('sh')) return 'shell';
+  if (/codex|claude|gemini|cursor|opencode/.test(title) || /codex|claude|gemini|cursor|opencode/.test(cmdline)) return 'agent';
+  return 'shell';
+}
+
+function flattenOsWindow(osWindow = {}) {
+  const tabs = Array.isArray(osWindow.tabs) ? osWindow.tabs : [];
+  const windows = [];
+  for (const tab of tabs) {
+    const tabWindows = Array.isArray(tab.windows) ? tab.windows : [];
+    for (const window of tabWindows) {
+      windows.push({
+        id: Number.isFinite(window.id) ? window.id : null,
+        title: text(window.title),
+        cwd: text(window.cwd),
+        cmdline: Array.isArray(window.cmdline) ? window.cmdline : [],
+        pid: Number.isFinite(window.pid) ? window.pid : null,
+        isFocused: Boolean(window.is_focused || window.focused),
+        isActive: Boolean(window.is_active || window.active),
+        kind: classifyWindow(window),
+        tabId: Number.isFinite(tab.id) ? tab.id : null,
+        tabTitle: text(tab.title),
+      });
+    }
+  }
+  return windows;
+}
+
+function pickOsWindow(payload, options = {}) {
+  if (!Array.isArray(payload) || payload.length === 0) return null;
+  const targetId = Number.parseInt(options.osWindowId, 10);
+  if (Number.isFinite(targetId)) {
+    return payload.find((entry) => entry && entry.id === targetId) || payload[0];
+  }
+  return payload.find((entry) => entry && (entry.is_focused || entry.focused)) || payload[0];
+}
+
+function buildSessionLabel(options = {}) {
+  if (text(options.sessionLabel)) return text(options.sessionLabel);
+  const env = options.env || process.env;
+  const fromEnv = text(env.GUARDEX_SESSION_LABEL);
+  if (fromEnv) return fromEnv;
+  const repoRoot = text(options.repoRoot);
+  if (repoRoot) return path.basename(repoRoot);
+  return 'session';
+}
+
+function userLabel(options = {}) {
+  const env = options.env || process.env;
+  return text(env.USER) || text(env.LOGNAME) || (typeof os.userInfo === 'function' ? text(os.userInfo().username) : '') || 'user';
+}
+
+function emptyTree(options = {}) {
+  return {
+    user: userLabel(options),
+    sessionLabel: buildSessionLabel(options),
+    osWindowId: null,
+    windows: [],
+    error: '',
+  };
+}
+
+function readKittyTree(options = {}) {
+  const env = options.env || process.env;
+  const socket = text(options.socket || env.KITTY_LISTEN_ON);
+  if (!socket) {
+    return { ...emptyTree(options), error: 'no KITTY_LISTEN_ON socket' };
+  }
+  const bin = text(options.bin || env.GUARDEX_KITTY_BIN, DEFAULT_BIN);
+  const runner = typeof options.runner === 'function' ? options.runner : defaultRunner;
+  const result = runner(bin, buildLsArgs(socket), { env, timeout: options.timeoutMs });
+  if (!result || result.error || result.status !== 0) {
+    const msg = result && (result.stderr || result.error || '').toString().trim();
+    return { ...emptyTree(options), error: msg || 'kitty @ ls failed' };
+  }
+  let payload;
+  try {
+    payload = JSON.parse(String(result.stdout || ''));
+  } catch (error) {
+    return { ...emptyTree(options), error: `parse error: ${error.message}` };
+  }
+  const osWindow = pickOsWindow(payload, options);
+  if (!osWindow) {
+    return { ...emptyTree(options), error: 'no os-window in kitty tree' };
+  }
+  return {
+    user: userLabel(options),
+    sessionLabel: buildSessionLabel(options),
+    osWindowId: Number.isFinite(osWindow.id) ? osWindow.id : null,
+    windows: flattenOsWindow(osWindow),
+    error: '',
+  };
+}
+
+module.exports = {
+  DEFAULT_BIN,
+  DEFAULT_TIMEOUT_MS,
+  buildLsArgs,
+  classifyWindow,
+  emptyTree,
+  flattenOsWindow,
+  pickOsWindow,
+  readKittyTree,
+  userLabel,
+  buildSessionLabel,
+};
diff --git a/src/cockpit/sidebar.js b/src/cockpit/sidebar.js
index ebba35b..0c4ab3a 100644
--- a/src/cockpit/sidebar.js
+++ b/src/cockpit/sidebar.js
@@ -199,6 +199,54 @@ function fitRow(left, right, width) {
   return `${truncate(left, leftWidth).padEnd(leftWidth, ' ')}${right}`;
 }
 
+function kittyTreeOf(state = {}) {
+  const tree = state && typeof state === 'object' ? state.kittyTree : null;
+  return tree && typeof tree === 'object' ? tree : null;
+}
+
+function classifyTag(window = {}) {
+  if (window.kind === 'control') return 'gx';
+  if (window.kind === 'agent') return 'cx';
+  if (window.kind === 'shell') return 'ba';
+  return 'sh';
+}
+
+function windowLabel(window = {}, fallback) {
+  const explicit = text(window.title);
+  if (explicit) return explicit;
+  if (window.kind === 'control') return 'gx cockpit';
+  if (Array.isArray(window.cmdline) && window.cmdline.length > 0) {
+    return path.basename(text(window.cmdline[0])) || fallback;
+  }
+  return fallback;
+}
+
+function renderKittyTreeRows(state, width, options = {}) {
+  const tree = kittyTreeOf(state);
+  if (!tree) return [];
+  const theme = getCockpitTheme(options.theme || (state.settings && state.settings.theme), options);
+  const windows = Array.isArray(tree.windows) ? tree.windows : [];
+  const lines = [];
+  lines.push(colorize(boundLine(text(tree.user, 'user'), width), 'title', theme));
+  lines.push(colorize(boundLine(`  ${text(tree.sessionLabel, 'session')}`, width), 'secondary', theme));
+  if (windows.length === 0) {
+    lines.push(colorize(boundLine('    no kitty panes detected', width), 'secondary', theme));
+  } else {
+    windows.forEach((window, index) => {
+      const cursor = window.isFocused ? '>' : ' ';
+      const label = windowLabel(window, `pane-${index + 1}`);
+      const tag = classifyTag(window);
+      const row = `  ${cursor} ${label}`.padEnd(Math.max(width - 6, 6), ' ') + ` [${tag}]`;
+      const token = window.isFocused ? 'selected' : 'secondary';
+      lines.push(colorize(boundLine(row, width), token, theme));
+    });
+  }
+  if (tree.error) {
+    lines.push(colorize(boundLine(`  (kitty: ${tree.error})`, width), 'secondary', theme));
+  }
+  return lines;
+}
+
 function renderShortcutRows(width, options) {
   const theme = getCockpitTheme(options.theme, options);
   const rows = [
@@ -243,6 +291,12 @@ function renderSidebar(state = {}, options = {}) {
     });
   }
 
+  const treeRows = renderKittyTreeRows(state, width, options);
+  if (treeRows.length > 0) {
+    lines.push('');
+    lines.push(...treeRows);
+  }
+
   lines.push(...renderShortcutRows(width, options));
 
   return `${lines.join('\n')}\n`;
diff --git a/test/cockpit-kitty-tree.test.js b/test/cockpit-kitty-tree.test.js
new file mode 100644
index 0000000..ea6b245
--- /dev/null
+++ b/test/cockpit-kitty-tree.test.js
@@ -0,0 +1,125 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const test = require('node:test');
+
+const {
+  buildLsArgs,
+  classifyWindow,
+  emptyTree,
+  flattenOsWindow,
+  pickOsWindow,
+  readKittyTree,
+} = require('../src/cockpit/kitty-tree');
+const { renderSidebar } = require('../src/cockpit/sidebar');
+
+function stripAnsi(value) {
+  return String(value).replace(/\x1b\[[0-9;]*m/g, '');
+}
+
+test('buildLsArgs targets a custom socket when provided', () => {
+  assert.deepEqual(buildLsArgs('unix:/tmp/x.sock'), ['@', '--to=unix:/tmp/x.sock', 'ls']);
+  assert.deepEqual(buildLsArgs(''), ['@', 'ls']);
+});
+
+test('classifyWindow recognizes control, agents, and shells', () => {
+  assert.equal(classifyWindow({ title: 'gx cockpit' }), 'control');
+  assert.equal(classifyWindow({ title: 'agent codex/foo' }), 'agent');
+  assert.equal(classifyWindow({ title: 'codex login' }), 'agent');
+  assert.equal(classifyWindow({ title: 'terminal' }), 'shell');
+  assert.equal(classifyWindow({ cmdline: ['/bin/bash'] }), 'shell');
+  assert.equal(classifyWindow({ title: 'random' }), 'shell');
+});
+
+test('flattenOsWindow extracts windows from nested tabs', () => {
+  const osWindow = {
+    id: 1,
+    tabs: [
+      {
+        id: 10,
+        title: 'main',
+        windows: [
+          { id: 100, title: 'gx cockpit', cwd: '/repo', is_focused: true, cmdline: ['gx', 'cockpit', 'control'] },
+          { id: 101, title: 'shell-1', cwd: '/repo', cmdline: ['/bin/bash'] },
+        ],
+      },
+    ],
+  };
+  const windows = flattenOsWindow(osWindow);
+  assert.equal(windows.length, 2);
+  assert.equal(windows[0].kind, 'control');
+  assert.equal(windows[0].isFocused, true);
+  assert.equal(windows[1].kind, 'shell');
+});
+
+test('pickOsWindow defaults to the focused entry', () => {
+  const payload = [
+    { id: 1, is_focused: false, tabs: [] },
+    { id: 2, is_focused: true, tabs: [] },
+  ];
+  assert.equal(pickOsWindow(payload).id, 2);
+  assert.equal(pickOsWindow(payload, { osWindowId: 1 }).id, 1);
+  assert.equal(pickOsWindow([]), null);
+});
+
+test('readKittyTree returns empty tree when KITTY_LISTEN_ON is unset', () => {
+  const result = readKittyTree({ env: {} });
+  assert.deepEqual(result.windows, []);
+  assert.match(result.error, /no KITTY_LISTEN_ON/);
+});
+
+test('readKittyTree parses kitty @ ls JSON output', () => {
+  const stdout = JSON.stringify([{
+    id: 7,
+    is_focused: true,
+    tabs: [{
+      id: 1,
+      windows: [
+        { id: 11, title: 'gx cockpit', cwd: '/repo', is_focused: true, cmdline: ['gx', 'cockpit'] },
+        { id: 12, title: 'codex codex', cwd: '/repo', cmdline: ['codex'] },
+        { id: 13, title: 'shell-1', cwd: '/repo', cmdline: ['/bin/bash'] },
+      ],
+    }],
+  }]);
+  const result = readKittyTree({
+    env: { KITTY_LISTEN_ON: 'unix:/tmp/test.sock', USER: 'deadpool' },
+    runner: () => ({ status: 0, stdout }),
+  });
+  assert.equal(result.error, '');
+  assert.equal(result.user, 'deadpool');
+  assert.equal(result.osWindowId, 7);
+  assert.equal(result.windows.length, 3);
+  assert.equal(result.windows[0].kind, 'control');
+  assert.equal(result.windows[1].kind, 'agent');
+  assert.equal(result.windows[2].kind, 'shell');
+});
+
+test('renderSidebar surfaces the kitty tree above the shortcut block when populated', () => {
+  const state = {
+    repoPath: '/work/gitguardex',
+    sessions: [],
+    kittyTree: {
+      user: 'deadpool',
+      sessionLabel: 'gitguardex',
+      osWindowId: 7,
+      windows: [
+        { id: 11, title: 'gx cockpit', kind: 'control', isFocused: true },
+        { id: 12, title: 'codex codex', kind: 'agent', isFocused: false },
+        { id: 13, title: 'shell-1', kind: 'shell', isFocused: false },
+      ],
+      error: '',
+    },
+  };
+  const output = stripAnsi(renderSidebar(state, { width: 38, noColor: true }));
+  assert.match(output, /^deadpool$/m);
+  assert.match(output, /^  gitguardex/m);
+  assert.match(output, />\s+gx cockpit/);
+  assert.match(output, /codex codex/);
+  assert.match(output, /shell-1/);
+  assert.match(output, /\[n\]ew agent/);
+});
+
+test('renderSidebar omits the kitty tree section when none is present', () => {
+  const output = stripAnsi(renderSidebar({ repoPath: '/work/gitguardex', sessions: [] }, { width: 32, noColor: true }));
+  assert.doesNotMatch(output, /^deadpool$/m);
+});