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#1595 · Bare repo + worktrees layout is not detected as a git repository

Bug Medium Effort: Small workspaces open on GitHub 2026-08-18 base 16ceb3a540f81c1189efaffb27a39b1d9443abf5 (main)

Verdict: REPRODUCED · root-cause confidence: high · linked open PRs: none

TL;DR

Plain-language framing. Some git users keep a project as a folder that contains a bare clone (a repository with no checked-out files, here .bare/), a one-line .git file that says gitdir: ./.bare, and one sibling folder per branch created with git worktree add. The folder root is a real git repository as far as git is concerned (git rev-parse --git-dir, git worktree list, git symbolic-ref HEAD all work), but it is not a work tree: there is no checkout in the root itself.

When such a root is registered as a bb project source, bb's host daemon decides the path is "not a git repository". Every git-gated feature that keys off the project source then turns off: the "New worktree" option in the environment picker is disabled, GET /api/v1/projects/:id/branches returns checkout.kind = "unknown" with reason "Path is not a git repository", and if you bypass the UI (CLI bb thread spawn --new-environment worktree) provisioning fails with not_git_repo: "Cannot create a worktree because the source is not a Git repository".

The cause is exactly what the reporter guessed: the single helper detectGitRepo() in packages/host-workspace/src/git.ts runs git rev-parse --is-inside-work-tree and treats false as "not git". A bare repository answers false with exit code 0. Every gate (ensureGitRepo, readGitRepositoryState, getCheckoutRef, host.list_branches, createWorktree) sits on that one helper. Note the reporter's proposed fallback --is-inside-git-dir does not work for this layout (it prints false in the root, because the root only points at the git dir); --is-bare-repository or --git-dir do. A prototype fix (distinguish "work tree" from "bare source" and let bare sources through the source-side gates) makes the branches endpoint, the picker, and end-to-end worktree provisioning work on this layout, with all host-workspace and host-daemon tests still passing.

The second half of the issue ("Existing worktree" only lists bb-managed environments, not git worktree list output) is accurate but is a feature request rather than a bug, and it is already tracked as #1624.

Claims vs findings

Environment

• bb 16ceb3a54 (main, 2026-08-18) checked out in worktree /home/sawyer/projects/bb/.claude/worktrees/wf_242c3e11-a10-18. origin/main is 5 commits ahead (a108fa7ef); none touch packages/host-workspace or host-branches.ts, so the bug is still present there.
• Linux 7.0.0-29-generic, node v24.18.0, git 2.53.0, codex-cli 0.147.0 (provider codex).
• Dev instance: app :14008, server :22008, host daemon :30008, data dir /home/sawyer/.bb-dev/projects-bb-.claude-worktrees-wf_242c3e11-a10-18-4ec3be00bc05, machine host_by68ynypfv ("bee").
• Projects: proj_mcn754hcb8 "cosmos" → /tmp/bb-1595/cosmos (bare layout); control proj_87t2bdjuvh "plain" → /tmp/bb-1595/plain (ordinary clone of the same origin).

Minimal reproduction

1. Build the layout (30 s, no bb needed)

Script 1595/repro/make-bare-layout.sh creates /tmp/bb-1595/{origin,cosmos} exactly like the issue (cosmos/.bare, cosmos/.git = gitdir: ./.bare, worktrees feature-a, feature-b) and prints the git probes. Output (make-bare-layout.out):

$ /tmp/bb-reports/issues/1595/repro/make-bare-layout.sh /tmp/bb-1595
--- git worktree list
/tmp/bb-1595-probe/cosmos/.bare     (bare)
/tmp/bb-1595-probe/cosmos/feature-a 1cec1d1 [feature-a]
/tmp/bb-1595-probe/cosmos/feature-b 1cec1d1 [feature-b]
--- rev-parse --is-inside-work-tree
false
exit=0
--- rev-parse --is-bare-repository
true
--- rev-parse --is-inside-git-dir
false
--- rev-parse --git-dir
/tmp/bb-1595-probe/cosmos/.bare
--- symbolic-ref --short HEAD
main
--- rev-parse --verify HEAD
1cec1d18f0d97f5d6b856bdd95e2aeeed8317901
--- status --porcelain (fails in a bare repo)
fatal: this operation must be run in a work tree
exit=128

Note --is-inside-work-tree = false with exit 0 (this is what bb checks), --is-inside-git-dir = false (the reporter's suggested fallback would not help), --is-bare-repository = true.

2. Unit-level repro (fails on main)

1595/repro/git-bare-layout-1595.test.ts, copy to packages/host-workspace/test/ and run pnpm exec vitest run test/git-bare-layout-1595.test.ts from packages/host-workspace. It builds the same layout in a temp dir and asserts what the daemon relies on. On 16ceb3a54 three of four assertions fail (vitest-base.txt): readGitRepositoryState returns not_git (expected has_commits), getCheckoutRef returns {kind:"unknown", reason:"Path is not a git repository"}, and createWorktree rejects with WorkspaceError not_git_repo. The first test (git itself sees a repo) passes, proving the layout is valid.

 RUN  v4.1.1 /home/sawyer/projects/bb/.claude/worktrees/wf_242c3e11-a10-18/packages/host-workspace
 ❯  @bb/host-workspace  test/git-bare-layout-1595.test.ts (4 tests | 3 failed) 166ms
     × readGitRepositoryState() reports has_commits for the bare root 43ms
     × getCheckoutRef() does not report 'not a git repository' 35ms
     × createWorktree() can add a worktree from the bare root 39ms
⎯⎯⎯⎯⎯⎯⎯ Failed Tests 3 ⎯⎯⎯⎯⎯⎯⎯
 FAIL   @bb/host-workspace  test/git-bare-layout-1595.test.ts > bare repo + worktrees layout (#1595) > readGitRepositoryState() reports has_commits for the bare root
AssertionError: expected 'not_git' to be 'has_commits' // Object.is equality
Expected: "has_commits"
Received: "not_git"
 ❯ test/git-bare-layout-1595.test.ts:64:48
     62|     const { root } = await initBareLayout();
     63|     // FAILS on 16ceb3a54: returns "not_git".
     64|     expect(await readGitRepositoryState(root)).toBe("has_commits");
       |                                                ^
     65|   });
     66|
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[1/3]⎯
 FAIL   @bb/host-workspace  test/git-bare-layout-1595.test.ts > bare repo + worktrees layout (#1595) > getCheckoutRef() does not report 'not a git repository'
AssertionError: expected 'unknown' not to be 'unknown' // Object.is equality
 ❯ test/git-bare-layout-1595.test.ts:73:31
     71|     // This is exactly what host.list_branches returns to the app, whi…
     72|     // disables "New worktree" in the environment picker.
     73|     expect(checkout.kind).not.toBe("unknown");
       |                               ^
     74|   });
     75|
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[2/3]⎯
 FAIL   @bb/host-workspace  test/git-bare-layout-1595.test.ts > bare repo + worktrees layout (#1595) > createWorktree() can add a worktree from the bare root
AssertionError: promise rejected "WorkspaceError: Cannot create a worktree … { code: '…' }" instead of resolving
 ❯ test/git-bare-layout-1595.test.ts:89:6
     87|         timeoutMs: 60_000,
     88|       }),
     89|     ).resolves.toEqual({ path: targetPath });
       |      ^
     90|   });
     91| });
Caused by: WorkspaceError: Cannot create a worktree because the source is not a Git repository: /tmp/bb-1595-PUf3Cw/cosmos. Initialize it and create at least one commit, then try again.
 ❯ createWorktree src/provisioning.ts:348:13
 ❯ test/git-bare-layout-1595.test.ts:81:5
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Serialized Error: { code: 'not_git_repo' }
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[3/3]⎯
 Test Files  1 failed (1)
      Tests  3 failed | 1 passed (4)
   Start at  07:39:00
   Duration  611ms (transform 226ms, setup 0ms, import 362ms, tests 166ms, environment 0ms)

// Repro for get-bb/bb#1595: a "bare repo + worktrees" project root
// (`<root>/.bare` bare clone, `<root>/.git` = "gitdir: ./.bare", worktrees
// as siblings) is not detected as a git repository by host-workspace, so the
// worktree flows are disabled / fail with not_git_repo.
import fs from "node:fs/promises";
import os from "node:os";
import path from "node:path";
import { afterEach, describe, expect, it } from "vitest";
import {
  getCheckoutRef,
  readGitRepositoryState,
  runGit,
} from "../src/git.js";
import { createWorktree } from "../src/provisioning.js";

const tempDirs: string[] = [];

afterEach(async () => {
  await Promise.all(
    tempDirs.splice(0).map((dir) => fs.rm(dir, { recursive: true, force: true })),
  );
});

async function initBareLayout(): Promise<{ root: string }> {
  const base = await fs.mkdtemp(path.join(os.tmpdir(), "bb-1595-"));
  tempDirs.push(base);
  const origin = path.join(base, "origin");
  await fs.mkdir(origin);
  await runGit(["init", "-b", "main"], { cwd: origin });
  await runGit(["config", "user.name", "BB Tests"], { cwd: origin });
  await runGit(["config", "user.email", "bb@example.com"], { cwd: origin });
  await fs.writeFile(path.join(origin, "README.md"), "hello\n", "utf8");
  await runGit(["add", "."], { cwd: origin });
  await runGit(["commit", "-m", "Initial commit"], { cwd: origin });
  await runGit(["branch", "feature-a"], { cwd: origin });

  // ~/www/cosmos layout from the issue.
  const root = path.join(base, "cosmos");
  await fs.mkdir(root);
  await runGit(["clone", "--bare", origin, ".bare"], { cwd: root });
  await fs.writeFile(path.join(root, ".git"), "gitdir: ./.bare\n", "utf8");
  await runGit(["worktree", "add", "feature-a", "feature-a"], { cwd: root });
  return { root };
}

describe("bare repo + worktrees layout (#1595)", () => {
  it("git itself recognises the root as a repository", async () => {
    const { root } = await initBareLayout();
    const gitDir = await runGit(["rev-parse", "--git-dir"], { cwd: root });
    expect(gitDir.stdout.trim()).toBe(path.join(root, ".bare"));
    const bare = await runGit(["rev-parse", "--is-bare-repository"], {
      cwd: root,
    });
    expect(bare.stdout.trim()).toBe("true");
    const list = await runGit(["worktree", "list", "--porcelain"], {
      cwd: root,
    });
    expect(list.stdout).toContain("branch refs/heads/feature-a");
  });

  it("readGitRepositoryState() reports has_commits for the bare root", async () => {
    const { root } = await initBareLayout();
    // FAILS on 16ceb3a54: returns "not_git".
    expect(await readGitRepositoryState(root)).toBe("has_commits");
  });

  it("getCheckoutRef() does not report 'not a git repository'", async () => {
    const { root } = await initBareLayout();
    const checkout = await getCheckoutRef(root);
    // FAILS on 16ceb3a54: { kind: "unknown", reason: "Path is not a git repository" }
    // This is exactly what host.list_branches returns to the app, which then
    // disables "New worktree" in the environment picker.
    expect(checkout.kind).not.toBe("unknown");
  });

  it("createWorktree() can add a worktree from the bare root", async () => {
    const { root } = await initBareLayout();
    const targetPath = path.join(path.dirname(root), "wt-new");
    // FAILS on 16ceb3a54: throws WorkspaceError not_git_repo
    // "Cannot create a worktree because the source is not a Git repository".
    await expect(
      createWorktree({
        sourcePath: root,
        targetPath,
        branchName: "bb/new",
        baseBranch: "main",
        timeoutMs: 60_000,
      }),
    ).resolves.toEqual({ path: targetPath });
  });
});

3. API repro against a running instance

1. Start your dev instance (scripts/bb-dev-app current) and get the host id (BB_SERVER_URL=http://localhost:<server> pnpm bb:dev machine list).
2. Register the bare root as a project:

   $ curl -s -X POST $BB_SERVER_URL/api/v1/projects -H 'content-type: application/json' \
       -d '{"name":"cosmos","source":{"type":"local_path","path":"/tmp/bb-1595/cosmos","hostId":"host_by68ynypfv"}}'
   {"id":"proj_mcn754hcb8","kind":"standard","name":"cosmos","gitRemoteUrl":"/tmp/bb-1595/origin","createdAt":1787038353264,"updatedAt":1787038353265,"sources":[{"id":"src_tjbeka2dxt","projectId":"proj_mcn754hcb8","type":"local_path","hostId":"host_by68ynypfv","path":"/tmp/bb-1595/cosmos","isDefault":true,"createdAt":1787038353264,"updatedAt":1787038353264}]}

   Note bb did read gitRemoteUrl from the bare repo (project.inspect runs git remote get-url origin without a work-tree gate, apps/host-daemon/src/command-handlers/project.ts#L49-L60), so bb is already inconsistent about whether this path is a repository.
3. Ask for branches (this is what the environment picker calls):

   $ curl -s "$BB_SERVER_URL/api/v1/projects/proj_mcn754hcb8/branches?hostId=host_by68ynypfv"
   {"branches":[],"branchesTruncated":false,"checkout":{"kind":"unknown","reason":"Path is not a git repository"},"defaultBranch":null,"defaultBranchRelation":null,"hasUncommittedChanges":false,"operation":{"kind":"none"},"originDefaultBranch":null,"remoteBranches":[],"remoteBranchesTruncated":false,"selectedBranch":null,"defaultWorktreeBaseBranch":null}

   Expected (control, plain clone of the same origin, proj_87t2bdjuvh):

   {"branches":["main"],"branchesTruncated":false,"checkout":{"kind":"branch","branchName":"main","headSha":"4ee97dc6c51317f663a7e4cbf2dba737d6b110e0"},"defaultBranch":"main","defaultBranchRelation":"equal","hasUncommittedChanges":false,"operation":{"kind":"none"},"originDefaultBranch":"origin/main","remoteBranches":["origin/main","origin/feature-a","origin/feature-b"],"remoteBranchesTruncated":false,"selectedBranch":null,"defaultWorktreeBaseBranch":"origin/main"}

   Actual: checkout.kind = "unknown", reason "Path is not a git repository", no branches. The app maps unknown to the disabled "New worktree" row (apps/app/src/views/root-compose-environment-selection.ts#L112-L125).
4. Bypass the UI and try to provision a worktree anyway:

   $ BB_SERVER_URL=http://localhost:22008 pnpm bb:dev thread spawn --project proj_mcn754hcb8 --machine host_by68ynypfv \
       --new-environment worktree --provider codex --title bare-wt --prompt "Reply only with ok." --json
     "id": "thr_jdknfv2g3g",
   $ pnpm bb:dev thread show thr_jdknfv2g3g
   Thread: thr_jdknfv2g3g
     Status: error
     Title: bare-wt
     Project: proj_mcn754hcb8
     Environment: Provisioning (env_kixveknw74)
       Pull request: unavailable
         HTTP 409: Environment unavailable
     Created: 8/18/2026, 7:33:34 AM
     Updated: 8/18/2026, 7:33:34 AM
   
   $ pnpm bb:dev thread log thr_jdknfv2g3g
   ── User ────────────────────────────────────────────────────
   Reply only with ok.
   
   ── Provisioning thread failed ──────────────────────────────
     Preparing worktree
     Workspace setup failed (30ms)
   
   ── Error ───────────────────────────────────────────────────
     Provisioning thread failed
     Cannot create a worktree because the source is not a Git repository: /tmp/bb-1595/cosmos. Initialize it and create at least one commit, then try again.
   

   The environment record ends as "isGitRepo":false,"status":"error" (spawn-worktree-bare-env.json).

4. Visual repro

Root cause

packages/host-workspace/src/git.ts#L590-L599:

export async function detectGitRepo(cwd, options = {}): Promise<boolean> {
  const result = await runGit(["rev-parse", "--is-inside-work-tree"], { cwd, allowFailure: true, ... });
  return result.exitCode === 0 && trimOutput(result.stdout) === "true";
}

git rev-parse --is-inside-work-tree answers the question "is cwd inside a checkout?", not "is cwd a git repository?". In a bare repository (including a directory whose .git file points at a bare gitdir) git exits 0 and prints false. Everything downstream conflates the two questions:

• packages/host-workspace/src/git.ts#L602-L614 ensureGitRepo throws not_git_repo; used by readDefaultBranch, readDefaultBranchRefs, hasRef, hasUncommittedChanges, getWorkspaceGitOperation, and every Workspace git method.
• packages/host-workspace/src/git.ts#L618-L629 readGitRepositoryState returns "not_git", which packages/host-workspace/src/provisioning.ts#L346-L357 createWorktree turns into the "Cannot create a worktree because the source is not a Git repository" error seen in the CLI repro.
• packages/host-workspace/src/git.ts#L670-L676 getCheckoutRef returns {kind:"unknown", reason:"Path is not a git repository"}.
• apps/host-daemon/src/command-handlers/host-branches.ts#L133-L158 listHostBranches short-circuits on detectGitRepo and returns the empty payload with that checkout; the server route apps/server/src/routes/projects.ts#L832-L858 forwards it; the app's apps/app/src/views/root-compose-environment-selection.ts#L112-L125 maps unknown → disabled reason; apps/app/src/components/pickers/EnvironmentPicker.tsx#L513-L521 renders "New worktree" disabled.
• packages/host-workspace/src/provision.ts#L692-L694 marks any unmanaged workspace at that path isGitRepo=false, which also hides the git UI for a "Work locally" thread at the root (arguably correct there, since there is no checkout to diff).

Why the symptom follows: the picker's only signal for "can I create a worktree from this source?" is checkout.kind from host.list_branches, and the daemon answers "unknown / not a git repository" for any bare source. Independently, even a direct provisioning request dies at readGitRepositoryState. Both roads pass through detectGitRepo.

Deeper issue. bb uses one boolean (isGitRepo) for two different capabilities: "this path can be a source for worktrees / branch listing" (needs a git dir, bare is fine) and "this path is a workspace with a checkout" (needs a work tree: git status, diffs, commits all fail in a bare repo with fatal: this operation must be run in a work tree). A fix that simply flips detectGitRepo to also accept bare would make hasUncommittedChanges/getWorkspaceGitOperation (both called by listHostBranches) throw git_command_failed, and would enable diff/commit UI on a bare-root local workspace. The two notions have to be separated.

Introduced by 9cd0484b3 (2026-04-06) and unchanged since; not a regression.

Proposed fix (first principles)

Confidence high; a prototype is in 1595/repro/prototype-fix.diff and was exercised end to end (below). Shape:

1. In packages/host-workspace/src/git.ts add detectGitRepoKind(cwd) → "work-tree" | "bare" | "none" using one call, git rev-parse --is-inside-work-tree --is-bare-repository (exit ≠ 0 → none). Keep detectGitRepo = work-tree only (workspace semantics: diffs, status, commits) and add detectGitSource = work-tree or bare (source semantics).
2. Use the source variant where the path is a source: readGitRepositoryState (→ createWorktree), getCheckoutRef, ensureGitRepo callers that only read refs (readDefaultBranch, readDefaultBranchRefs, hasRef, listBranches), and the gate in listHostBranches.
3. Make the two work-tree-only helpers that listHostBranches also calls tolerate bare: hasUncommittedChanges → false, getWorkspaceGitOperation → {kind:"none"}.
4. Leave provision.ts's isGitRepo (workspace) semantics alone so a "Work locally" thread at the bare root keeps the git UI off. No wire shape changes, so no HOST_DAEMON_PROTOCOL_VERSION bump is needed; the disabled-reason strings in the app also stay valid.
5. Add the repro test (adjusted to the final helper names) to packages/host-workspace/test/.

What could go wrong: ensureGitRepo is also used by Workspace methods; if it is widened to bare, a caller that reaches those methods with a bare path would now fail with git_command_failed from git status/diff instead of a clean not_git_repo. Server routes gate on environment.isGitRepo (still false for bare workspaces) so this is unreachable today, but a cleaner variant keeps ensureGitRepo as-is and adds ensureGitSource for the ref-reading helpers. Also, a bare clone made with git clone --bare has no refs/remotes/origin/* and no fetch refspec, so remoteBranches is empty and defaultWorktreeBaseBranch falls back to the local main (visible in the fixed output); that is correct behaviour, not a bug. Worktree layouts where the root is the bare dir (no .git file, e.g. ~/cosmos.git/) are covered by the same --is-bare-repository check.

Evidence the prototype works (host-workspace + host-daemon rebuilt, dev instance restarted): the branches endpoint on the same project now returns

{"branches":["main","feature-a","feature-b","feature-c"],"branchesTruncated":false,"checkout":{"kind":"branch","branchName":"main","headSha":"4ee97dc6c51317f663a7e4cbf2dba737d6b110e0"},"defaultBranch":"main","defaultBranchRelation":null,"hasUncommittedChanges":false,"operation":{"kind":"none"},"originDefaultBranch":null,"remoteBranches":[],"remoteBranchesTruncated":false,"selectedBranch":null,"defaultWorktreeBaseBranch":"main"}

and the same CLI spawn provisions and runs (log):

── User ────────────────────────────────────────────────────
Reply only with ok.

── Provisioned thread ──────────────────────────────────────
  Preparing worktree
  Creating worktree
  HEAD is now at 4ee97dc init
  Preparing worktree (new branch 'bb/bare-wt-fixed-thr_rnwsxwbgd7')
  Created worktree (16ms)
  Using workspace: /home/sawyer/.bb-dev/projects-bb-.claude-worktrees-wf_242c3e11-a10-18-4ec3be00bc05/worktrees/env_gnmcx2fw5r/cosmos
  Using branch: bb/bare-wt-fixed-thr_rnwsxwbgd7 (4ee97dc)

── Assistant ───────────────────────────────────────────────
ok

git -C /tmp/bb-1595/cosmos worktree list afterwards shows the new bb worktree registered next to feature-a/feature-b. Repro test: 4/4 pass with the prototype (vitest-prototype-fix.txt); turbo run test --filter=@bb/host-workspace --filter=@bb/host-daemon: 217 + 582 tests pass (prototype-tests.txt).

diff --git a/apps/host-daemon/src/command-handlers/host-branches.ts b/apps/host-daemon/src/command-handlers/host-branches.ts
index 0f45e65ac..c246cc922 100644
--- a/apps/host-daemon/src/command-handlers/host-branches.ts
+++ b/apps/host-daemon/src/command-handlers/host-branches.ts
@@ -1,7 +1,7 @@
 import path from "node:path";
 import type { GitBranchRefClassification } from "@bb/domain";
 import {
-  detectGitRepo,
+  detectGitSource,
   fetchRemoteBranches,
   getCheckoutRef,
   getGitCommonDir,
@@ -137,7 +137,7 @@ export async function listHostBranches(
     throw new CommandDispatchError("invalid_path", "Path must be absolute");
   }
 
-  if (!(await detectGitRepo(command.path))) {
+  if (!(await detectGitSource(command.path))) {
     return {
       branches: [],
       branchesTruncated: false,
diff --git a/packages/host-workspace/src/git.ts b/packages/host-workspace/src/git.ts
index c60fe6dd1..7f5d204dc 100644
--- a/packages/host-workspace/src/git.ts
+++ b/packages/host-workspace/src/git.ts
@@ -587,23 +587,58 @@ async function findWorkspaceGitOperationMarker(
   return undefined;
 }
 
+export type GitRepoKind = "work-tree" | "bare" | "none";
+
+/**
+ * Classifies `cwd`: inside a work tree, at/inside a bare repository (for
+ * example the "bare clone + sibling worktrees" layout where `<root>/.git`
+ * is a gitdir file pointing at `<root>/.bare`), or not a repository at all.
+ */
+export async function detectGitRepoKind(
+  cwd: string,
+  options: GitTimeoutOptions = {},
+): Promise<GitRepoKind> {
+  const result = await runGit(
+    ["rev-parse", "--is-inside-work-tree", "--is-bare-repository"],
+    { cwd, allowFailure: true, timeoutMs: options.timeoutMs },
+  );
+  if (result.exitCode !== 0) {
+    return "none";
+  }
+  const [insideWorkTree, bare] = trimOutput(result.stdout).split("\n");
+  if (insideWorkTree === "true") {
+    return "work-tree";
+  }
+  if (bare === "true") {
+    return "bare";
+  }
+  return "none";
+}
+
+/** True when `cwd` is inside a git work tree (a checkout). */
 export async function detectGitRepo(
   cwd: string,
   options: GitTimeoutOptions = {},
 ): Promise<boolean> {
-  const result = await runGit(["rev-parse", "--is-inside-work-tree"], {
-    cwd,
-    allowFailure: true,
-    timeoutMs: options.timeoutMs,
-  });
-  return result.exitCode === 0 && trimOutput(result.stdout) === "true";
+  return (await detectGitRepoKind(cwd, options)) === "work-tree";
+}
+
+/**
+ * True when `cwd` is a git repository that can serve as the source of a
+ * worktree: a checkout or a bare repository.
+ */
+export async function detectGitSource(
+  cwd: string,
+  options: GitTimeoutOptions = {},
+): Promise<boolean> {
+  return (await detectGitRepoKind(cwd, options)) !== "none";
 }
 
 export async function ensureGitRepo(
   cwd: string,
   options: GitTimeoutOptions = {},
 ): Promise<void> {
-  if (await detectGitRepo(cwd, options)) {
+  if (await detectGitSource(cwd, options)) {
     return;
   }
 
@@ -619,7 +654,7 @@ export async function readGitRepositoryState(
   cwd: string,
   options: GitTimeoutOptions = {},
 ): Promise<GitRepositoryState> {
-  if (!(await detectGitRepo(cwd, options))) {
+  if (!(await detectGitSource(cwd, options))) {
     return "not_git";
   }
   const result = await runGit(["rev-list", "--all", "--max-count=1"], {
@@ -671,7 +706,7 @@ export async function getCheckoutRef(
   cwd: string,
   options: GitTimeoutOptions = {},
 ): Promise<GitCheckoutRef> {
-  if (!(await detectGitRepo(cwd, options))) {
+  if (!(await detectGitSource(cwd, options))) {
     return { kind: "unknown", reason: "Path is not a git repository" };
   }
 
@@ -867,6 +902,9 @@ export async function getWorkspaceGitOperation(
   cwd: string,
 ): Promise<WorkspaceGitOperation> {
   await ensureGitRepo(cwd);
+  if ((await detectGitRepoKind(cwd)) === "bare") {
+    return { kind: "none" };
+  }
 
   const [gitDir, status] = await Promise.all([
     getAbsoluteGitDir(cwd),
@@ -1467,6 +1505,10 @@ export async function listRemoteBranches(cwd: string): Promise<string[]> {
 
 export async function hasUncommittedChanges(cwd: string): Promise<boolean> {
   await ensureGitRepo(cwd);
+  if ((await detectGitRepoKind(cwd)) === "bare") {
+    // A bare repository has no index or work tree to be dirty.
+    return false;
+  }
   const status = await runGit(
     ["--no-optional-locks", "status", "--porcelain=v1", "--untracked-files=all"],
     { cwd },
diff --git a/packages/host-workspace/src/index.ts b/packages/host-workspace/src/index.ts
index cb9c4a522..2c43d292d 100644
--- a/packages/host-workspace/src/index.ts
+++ b/packages/host-workspace/src/index.ts
@@ -30,6 +30,8 @@ export type {
 export {
   WorkspaceError,
   detectGitRepo,
+  detectGitRepoKind,
+  detectGitSource,
   fetchRemoteBranches,
   getCheckoutRef,
   getCurrentBranch,

PR review

No open PRs are linked to this issue.

Related issues

• #1624 Support discovered worktrees and continuing existing branches — covers the second half of this issue (list git worktree list output in "Existing worktree").
• PR #1396 (893a05ae6) changed the disabled-reason wording from "Project source is not a git repository" to "New worktrees require a Git repository with at least one commit"; the underlying checkout.kind === "unknown" path is unchanged.

Appendix

Commands run

git checkout 16ceb3a54 && pnpm install --frozen-lockfile --prefer-offline && pnpm exec turbo run build
/tmp/bb-reports/issues/1595/repro/make-bare-layout.sh /tmp/bb-1595
scripts/bb-dev-app current                     # app :14008 server :22008 daemon :30008
BB_SERVER_URL=http://localhost:22008 pnpm bb:dev machine list      # host_by68ynypfv
curl -s -X POST http://localhost:22008/api/v1/projects -H 'content-type: application/json' -d '{"name":"cosmos","source":{"type":"local_path","path":"/tmp/bb-1595/cosmos","hostId":"host_by68ynypfv"}}'
curl -s "http://localhost:22008/api/v1/projects/proj_mcn754hcb8/branches?hostId=host_by68ynypfv"
git clone -q /tmp/bb-1595/origin /tmp/bb-1595/plain   # control project proj_87t2bdjuvh, same branches call
BB_SERVER_URL=http://localhost:22008 node packages/scripts/dist/commands/run-cli.js thread spawn --project proj_mcn754hcb8 --machine host_by68ynypfv --new-environment worktree --provider codex --title bare-wt --prompt "Reply only with ok." --json
... thread show / thread log thr_jdknfv2g3g ; curl .../environments/env_kixveknw74
cd packages/host-workspace && pnpm exec vitest run test/git-bare-layout-1595.test.ts     # 3 failed / 1 passed on base
git checkout -b bb/1595-prototype ; apply prototype diff ; vitest again (4 passed)
pnpm exec turbo run test --filter=@bb/host-workspace --filter=@bb/host-daemon --force
pnpm exec turbo run build --filter=@bb/host-daemon ; pnpm dev:stop ; scripts/bb-dev-app current
curl .../projects/proj_mcn754hcb8/branches?hostId=host_by68ynypfv   # now lists branches
... thread spawn again → thr_rnwsxwbgd7 idle, "ok"
dev-browser --browser bb1595 --headless run 1595/browser-picker*.js   # screenshots
pnpm dev:stop

Files

• create-project.json, branches-bare.json, branches-plain.json, branches-bare-prototype-fix.json
• spawn-worktree-bare-show.txt, spawn-worktree-bare-log.txt, spawn-worktree-bare-env.json, …-prototype-fix-show.txt, …-prototype-fix-log.txt
• repro/: make-bare-layout.sh, git-bare-layout-1595.test.ts, vitest-base.txt, vitest-prototype-fix.txt, prototype-fix.diff
• Browser scripts: browser-picker2.js (bare project), browser-picker3.js (control)