Add git worktree awareness to status line

Sessions in a linked worktree previously showed only the worktree's
directory name, so the underlying repository was unidentifiable and the
session looked like an unrelated project.

The project segment now renders as "repo | worktree". Repo identity comes
from git rev-parse --git-common-dir, so it is correct regardless of how the
worktree directory was named. A leading repo prefix is stripped from the
worktree name, and the name collapses to a bare marker when it merely
restates the branch already on screen -- matched across / _ . - separators
and type prefixes like feature/, and only when the branch is displayed.

Gated behind the new items.worktree config flag (default on). Costs one
extra timeout-bounded git call, skipped entirely outside git repos.

src/statusline-claude/README.md

@@ -20,6 +20,14 @@ A persistent three-line status bar for Claude Code that displays model info, pro
 ╰─╯  2m ($0.18) │ ▰▰▱▱▱▱▱▱▱▱▱▱ 18% (36k) │ 88k in · 3k out
 ```
 
+**Git worktree** — session running in a linked worktree at `C:\git\plan2code-user-auth`:
+
+```
+╭─╮  Opus 4.6 | High │ plan2code ⑂ │ feature/user-auth │ +12 -3
+│★│  ┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄
+╰─╯  3h 5m ($4.62) │ ▰▰▰▰▰▱▱▱▱▱▱▱ 42% (84k) │ 5h: 28% · 7d: 61%
+```
+
 **Line 1:** Planny icon | Model name + reasoning effort | Project name | Git branch | Uncommitted changes
 **Line 2:** Planny icon | Gray separator
 **Line 3:** Planny icon | Session duration + cost | Context window bar | Usage (rate limits or token counts)
@@ -65,6 +73,7 @@ Edit `~/.claude/statusline-config.json`:
     "model": true,
     "effort": true,
     "project": true,
+    "worktree": true,
     "branch": true,
     "contextBar": true,
     "planUsage": true,
@@ -83,6 +92,7 @@ Edit `~/.claude/statusline-config.json`:
 | `items.model` | `true` | Show model name (Opus, Sonnet, Haiku) |
 | `items.effort` | `true` | Append the current reasoning effort level (Low/Medium/High/XHigh/Max) to the model segment, e.g. `Sonnet 5 \| High`. Reads `effort.level` from stdin; hidden when the current model doesn't support an effort parameter (field absent from stdin). |
 | `items.project` | `true` | Show project directory name |
+| `items.worktree` | `true` | Detect [git worktrees](https://git-scm.com/docs/git-worktree) and render the project segment as `repo ⑂ worktree` instead of just the worktree's directory name. See [Worktree Display](#worktree-display). Requires `items.project`. |
 | `items.branch` | `true` | Show current git branch (falls back to short SHA when detached HEAD) |
 | `items.contextBar` | `true` | Show context window usage bar with percentage |
 | `items.contextTokens` | `true` | Append raw tokens used in the context window next to the percentage, e.g. `42% (84k)`. Reads `context_window.total_input_tokens` (the same input-token count `used_percentage` is derived from — excludes output tokens). Requires `items.contextBar` to also be enabled. |
@@ -101,6 +111,27 @@ Malformed config falls back to defaults silently. Type errors on individual keys
 | Copilot CLI | Planned | Deferred — CLI lacks status line script support as of v0.0.421 |
 | Others | Not supported | Codex CLI, Gemini CLI have built-in status, not scriptable |
 
+## Worktree Display
+
+With `items.worktree` disabled, a session in a linked worktree shows only that worktree's directory name (`plan2code-user-auth`) — the underlying repository identity is lost, and the session looks like an unrelated project.
+
+When enabled, the project segment becomes `repo ⑂ worktree`:
+
+| Worktree directory | Branch | Rendered | Why |
+|--------------------|--------|----------|-----|
+| `plan2code` (primary checkout) | `main` | `plan2code` | Not a linked worktree — unchanged |
+| `plan2code-spike` | `spike-thing` | `plan2code ⑂ spike` | Repo prefix stripped from the worktree name |
+| `plan2code-user-auth` | `feature/user-auth` | `plan2code ⑂` | Name is redundant with the visible branch — collapses to the bare marker |
+| `plan2code-user-auth` | `feature/user-auth`, `items.branch: false` | `plan2code ⑂ user-auth` | No branch shown, so the name is kept |
+
+Details:
+
+- **Detection** — a single `git rev-parse --git-dir --git-common-dir`. The two paths differ only inside a linked worktree. The true repo name comes from `--git-common-dir` (its parent directory, or the `<name>.git` basename for a bare main repo), so it is correct regardless of how the worktree directory was named.
+- **Prefix stripping** — a leading repo name followed by `-`, `_`, or `.` is removed, so `plan2code-user-auth` reads as `user-auth`.
+- **Redundancy collapse** — worktree directories usually mirror their branch. The name is dropped (leaving `⑂`) when it matches the branch after normalizing case and `/ _ . -` separators, compared against both the full branch and its trailing segment so type prefixes like `feature/` don't defeat the match. This only applies when the branch is actually displayed.
+- **Color** — the repo keeps its bold silver; the `⑂` marker and worktree name render in amber so a non-primary checkout is obvious at a glance. Monochrome output is `repo ⑂ worktree`.
+- **Cost** — one extra `git` invocation, subject to the same 1.5s timeout, and skipped entirely outside git repos.
+
 ## Usage Display
 
 The usage segment reads data directly from Claude Code's stdin JSON — no API calls, no auth needed, no background processes.

src/statusline-claude/statusline-config.json

@@ -6,6 +6,7 @@
     "model": true,
     "effort": true,
     "project": true,
+    "worktree": true,
     "branch": true,
     "contextBar": true,
     "contextTokens": true,

src/statusline-claude/statusline.js

@@ -28,6 +28,7 @@ const DEFAULTS = {
     model: true,
     effort: true,
     project: true,
+    worktree: true,
     branch: true,
     contextBar: true,
     contextTokens: true,
@@ -90,6 +91,7 @@ const C = {
   // Plan2Code brand
   teal: rgb(190, 192, 200),     // Silver — repo
   sky: rgb(120, 195, 255),      // Light sky blue — branch
+  amber: rgb(235, 170, 95),     // Amber — linked worktree marker
   muted: rgb(40, 120, 200),     // Mid blue — model
   label: rgb(130, 135, 150),    // Mid gray — field labels (5h, 7d)
   // Bar & quota thresholds
@@ -150,6 +152,54 @@ function getGitBranch(stdinData) {
   return sha || '';
 }
 
+// Linked worktrees have their own .git dir under the main repo's
+// .git/worktrees/<name>, while --git-common-dir still points at the main repo's
+// .git. Equal paths mean we're in the primary checkout.
+function getWorktreeInfo(cwd) {
+  const raw = gitExec(['rev-parse', '--git-dir', '--git-common-dir'], cwd);
+  if (!raw) return null;
+
+  const [gitDir, commonDir] = raw.split('\n').map((p) => path.resolve(cwd, p.trim()));
+  if (!gitDir || !commonDir) return null;
+
+  const samePath = process.platform === 'win32'
+    ? gitDir.toLowerCase() === commonDir.toLowerCase()
+    : gitDir === commonDir;
+  if (samePath) return null;
+
+  // commonDir is normally <repo>/.git; bare repos use <name>.git directly
+  const commonBase = path.basename(commonDir);
+  const repoName = commonBase === '.git'
+    ? path.basename(path.dirname(commonDir))
+    : commonBase.replace(/\.git$/i, '');
+
+  const toplevel = gitExec(['rev-parse', '--show-toplevel'], cwd);
+  const worktreeName = path.basename(toplevel || cwd);
+  if (!repoName || !worktreeName) return null;
+
+  return { repoName, worktreeName };
+}
+
+// "plan2code-user-auth" in repo "plan2code" reads as just "user-auth"
+function stripRepoPrefix(worktreeName, repoName) {
+  const lowerWt = worktreeName.toLowerCase();
+  const lowerRepo = repoName.toLowerCase();
+  if (!lowerWt.startsWith(lowerRepo) || lowerWt === lowerRepo) return worktreeName;
+  const rest = worktreeName.slice(repoName.length);
+  return /^[-_.]/.test(rest) ? rest.slice(1) : worktreeName;
+}
+
+const normalizeName = (s) => s.toLowerCase().replace(/[/_.\s-]+/g, '-').replace(/^-|-$/g, '');
+
+// Worktree dirs usually mirror their branch (plan2code-user-auth / feature/user-auth).
+// Compare against both the full branch and its trailing segment so the common
+// type prefixes (feature/, bugfix/, ...) don't defeat the match.
+function isRedundantWithBranch(worktreeName, branch) {
+  if (!branch) return false;
+  const candidates = new Set([normalizeName(branch), normalizeName(branch.split('/').pop())]);
+  return candidates.has(normalizeName(worktreeName));
+}
+
 // ============================================================================
 // Formatters
 // ============================================================================
@@ -192,6 +242,34 @@ function getProjectName(stdinData) {
   return path.basename(projectDir);
 }
 
+// Returns the project segment: "plan2code" normally, "plan2code ⑂ spike" in a
+// linked worktree — the name collapsing to a bare ⑂ when the branch says it already.
+function formatProject(stdinData, config, branch) {
+  const project = getProjectName(stdinData);
+  if (!project) return null;
+  const plain = (text) => (config.color ? `${C.bold}${C.teal}${text}${C.reset}` : text);
+
+  if (!config.items.worktree) return plain(project);
+
+  const cwd = stdinData?.workspace?.project_dir || process.cwd();
+  if (!isGitRepo(cwd)) return plain(project);
+
+  const info = getWorktreeInfo(cwd);
+  if (!info) return plain(project);
+
+  const shortName = stripRepoPrefix(info.worktreeName, info.repoName);
+  // Only dedupe against a branch the user can actually see — otherwise the
+  // worktree identity would vanish entirely.
+  const visibleBranch = config.items.branch ? branch : '';
+  const redundant = isRedundantWithBranch(shortName, visibleBranch)
+    || isRedundantWithBranch(info.worktreeName, visibleBranch)
+    || normalizeName(shortName) === normalizeName(info.repoName);
+  const marker = redundant ? '⑂' : `⑂ ${shortName}`;
+
+  if (!config.color) return `${info.repoName} ${marker}`;
+  return `${C.bold}${C.teal}${info.repoName}${C.reset} ${C.amber}${marker}${C.reset}`;
+}
+
 function calculateContextPercent(stdinData, config) {
   const cw = stdinData?.context_window;
   if (!cw) return null;
@@ -339,14 +417,16 @@ function formatLine1(stdinData, config) {
     }
   }
 
+  // Branch is resolved first — the project segment dedupes the worktree name against it
+  const branch = config.items.branch || config.items.worktree ? getGitBranch(stdinData) : '';
+
   if (config.items.project) {
-    const project = getProjectName(stdinData);
+    const project = formatProject(stdinData, config, branch);
-    if (project) segments.push(config.color ? `${C.bold}${C.teal}${project}${C.reset}` : project);
+    if (project) segments.push(project);
   }
 
-  if (config.items.branch) {
+  if (config.items.branch && branch) {
-    const branch = getGitBranch(stdinData);
+    segments.push(config.color ? `${C.sky}${branch}${C.reset}` : branch);
-    if (branch) segments.push(config.color ? `${C.sky}${branch}${C.reset}` : branch);
   }
 
   if (config.items.linesChanged) {