fix(extensions): stop the git extension's fetch from waiting on a credential prompt

extensions/git/scripts/bash/create-new-feature-branch.sh

@@ -191,7 +191,7 @@ check_existing_branches() {
             highest_branch=$highest_remote
         fi
     else
-        git fetch --all --prune >/dev/null 2>&1 || true
+        GIT_TERMINAL_PROMPT=0 git fetch --all --prune >/dev/null 2>&1 || true
         local highest_branch=$(get_highest_from_branches "$scope_prefix")
     fi
 

extensions/git/scripts/powershell/create-new-feature-branch.ps1

@@ -162,9 +162,14 @@ function Get-NextBranchNumber {
         $highestRemote = Get-HighestNumberFromRemoteRefs -ScopePrefix $ScopePrefix
         $highestBranch = [Math]::Max($highestBranch, $highestRemote)
     } else {
+        $previousTerminalPrompt = $env:GIT_TERMINAL_PROMPT
         try {
+            $env:GIT_TERMINAL_PROMPT = '0'
             git fetch --all --prune 2>$null | Out-Null
-        } catch { }
+        } catch {
+        } finally {
+            $env:GIT_TERMINAL_PROMPT = $previousTerminalPrompt
+        }
         $highestBranch = Get-HighestNumberFromBranches -ScopePrefix $ScopePrefix
     }
 

extensions/git/scripts/python/create_new_feature_branch.py

@@ -271,6 +271,7 @@ def check_existing_branches(
             cwd=repo_root,
             capture_output=True,
             text=True,
+            env={**os.environ, "GIT_TERMINAL_PROMPT": "0"},
         )
         highest_branch = get_highest_from_branches(repo_root, scope_prefix)
 

tests/extensions/git/test_git_extension.py

@@ -100,6 +100,40 @@ def _add_sibling_worktree(project: Path, path: Path, branch: str) -> None:
     )
 
 
+def _add_prompt_probe_remote(project: Path) -> Path:
+    """Add an ssh remote whose transport logs GIT_TERMINAL_PROMPT and fails.
+
+    Git runs core.sshCommand with the environment of the fetch or ls-remote
+    that contacts the remote, so the log shows whether git was allowed to
+    prompt for credentials. No network is used. Returns the log path.
+    """
+    git_dir = project / ".git"
+    probe = git_dir / "prompt-probe.sh"
+    probe.write_text(
+        "#!/bin/sh\n"
+        'echo "${GIT_TERMINAL_PROMPT-unset}" >> "$(dirname "$0")/prompt-probe.log"\n'
+        "exit 1\n",
+        encoding="utf-8",
+        newline="\n",
+    )
+    subprocess.run(
+        ["git", "remote", "add", "origin", "ssh://git@example.invalid/repo.git"],
+        cwd=project,
+        check=True,
+    )
+    subprocess.run(
+        ["git", "config", "core.sshCommand", f'sh "{probe.as_posix()}"'],
+        cwd=project,
+        check=True,
+    )
+    return git_dir / "prompt-probe.log"
+
+
+def _probe_log(log: Path) -> list[str]:
+    """GIT_TERMINAL_PROMPT values seen by the probe remote, one per contact."""
+    return log.read_text(encoding="utf-8").split() if log.exists() else []
+
+
 # Git identity env vars for CI runners without global git config
 _GIT_ENV = {
     "GIT_AUTHOR_NAME": "Test User",
@@ -583,6 +617,31 @@ def test_dry_run_preserves_literal_plus_branch_prefix(self, tmp_path: Path):
         assert data["BRANCH_NAME"] == "001-next"
         assert data["FEATURE_NUM"] == "001"
 
+    @pytest.mark.parametrize("extra_args", [(), ("--dry-run",)], ids=["fetch", "dry-run"])
+    def test_remote_lookup_disables_terminal_prompt(
+        self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch, extra_args: tuple[str, ...]
+    ):
+        """Branch numbering must not wait on a git credential prompt (#5199).
+
+        The redirects hide git's output but not a prompt written to the
+        terminal, so the fetch and the dry-run ls-remote both need
+        GIT_TERMINAL_PROMPT=0. A failing remote must not stop the script.
+        """
+        monkeypatch.delenv("GIT_TERMINAL_PROMPT", raising=False)
+        project = _setup_project(tmp_path)
+        log = _add_prompt_probe_remote(project)
+
+        result = _run_bash(
+            "create-new-feature-branch.sh", project,
+            "--json", *extra_args, "--short-name", "probe", "Probe feature",
+        )
+
+        assert result.returncode == 0, result.stderr
+        assert json.loads(result.stdout)["BRANCH_NAME"] == "001-probe"
+        calls = _probe_log(log)
+        assert calls, "the probe remote was never contacted"
+        assert set(calls) == {"0"}
+
     def test_no_git_graceful_degradation(self, tmp_path: Path):
         """create-new-feature-branch.sh works without git (outputs branch name, skips branch creation)."""
         project = _setup_project(tmp_path, git=False)
@@ -934,6 +993,57 @@ def test_git_branch_name_override_without_feature_marker_preserves_full_name(sel
         assert data["BRANCH_NAME"] == "jdoe/app-a/custom-branch"
         assert data["FEATURE_NUM"] == "jdoe/app-a/custom-branch"
 
+    @pytest.mark.parametrize("extra_args", [(), ("-DryRun",)], ids=["fetch", "dry-run"])
+    def test_remote_lookup_disables_terminal_prompt(
+        self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch, extra_args: tuple[str, ...]
+    ):
+        """Branch numbering must not wait on a git credential prompt (#5199)."""
+        monkeypatch.delenv("GIT_TERMINAL_PROMPT", raising=False)
+        project = _setup_project(tmp_path)
+        log = _add_prompt_probe_remote(project)
+
+        result = _run_pwsh(
+            "create-new-feature-branch.ps1", project,
+            "-Json", *extra_args, "-ShortName", "probe", "Probe feature",
+        )
+
+        assert result.returncode == 0, result.stderr
+        json_line = [ln for ln in result.stdout.splitlines() if ln.strip().startswith("{")]
+        assert json_line, f"No JSON in output: {result.stdout}"
+        assert json.loads(json_line[-1])["BRANCH_NAME"] == "001-probe"
+        calls = _probe_log(log)
+        assert calls, "the probe remote was never contacted"
+        assert set(calls) == {"0"}
+
+    @pytest.mark.parametrize("caller_value", ["1", None], ids=["set", "unset"])
+    def test_fetch_restores_caller_terminal_prompt(
+        self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch, caller_value: str | None
+    ):
+        """The fetch guard must not leak into, or clear, the caller's GIT_TERMINAL_PROMPT."""
+        if caller_value is None:
+            monkeypatch.delenv("GIT_TERMINAL_PROMPT", raising=False)
+        else:
+            monkeypatch.setenv("GIT_TERMINAL_PROMPT", caller_value)
+        project = _setup_project(tmp_path)
+        log = _add_prompt_probe_remote(project)
+        script = project / ".specify" / "extensions" / "git" / "scripts" / "powershell" / "create-new-feature-branch.ps1"
+        command = (
+            f"& '{script}' -Json -ShortName probe 'Probe feature' | Out-Null; "
+            "'after=' + [Environment]::GetEnvironmentVariable('GIT_TERMINAL_PROMPT')"
+        )
+        env = {**os.environ, **_GIT_ENV}
+        result = subprocess.run(
+            ["pwsh", "-NoProfile", "-Command", command],
+            cwd=project,
+            capture_output=True,
+            text=True,
+            env=env,
+        )
+
+        assert result.returncode == 0, result.stderr
+        assert set(_probe_log(log)) == {"0"}
+        assert result.stdout.splitlines()[-1] == f"after={caller_value or ''}"
+
     def test_no_git_graceful_degradation(self, tmp_path: Path):
         """create-new-feature-branch.ps1 works without git."""
         project = _setup_project(tmp_path, git=False)

tests/extensions/git/test_git_extension_python_parity.py

@@ -21,7 +21,9 @@
 from tests.extensions.git.test_git_extension import (
     _GIT_ENV,
     HAS_PWSH,
+    _add_prompt_probe_remote,
     _init_git,
+    _probe_log,
     _run_bash,
     _run_pwsh,
     _setup_project,
@@ -292,6 +294,27 @@ def test_numbering_from_specs_and_branches(self, tmp_path: Path):
         _assert_parity(b, p)
         assert json.loads(p.stdout)["FEATURE_NUM"] == "013"
 
+    def test_fetch_disables_terminal_prompt(
+        self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+    ):
+        """Both twins fetch with GIT_TERMINAL_PROMPT=0 and survive a failing remote (#5199)."""
+        monkeypatch.delenv("GIT_TERMINAL_PROMPT", raising=False)
+        bash_proj, py_proj = _twin_projects(tmp_path)
+        bash_log = _add_prompt_probe_remote(bash_proj)
+        py_log = _add_prompt_probe_remote(py_proj)
+        b = _run_bash(
+            "create-new-feature-branch.sh", bash_proj, "--json", "--short-name", "probe", "Probe feature"
+        )
+        p = _run_py(
+            "create-new-feature-branch", py_proj, "--json", "--short-name", "probe", "Probe feature"
+        )
+        _assert_parity(b, p)
+        assert json.loads(p.stdout)["BRANCH_NAME"] == "001-probe"
+        for log in (bash_log, py_log):
+            calls = _probe_log(log)
+            assert calls, "the probe remote was never contacted"
+            assert set(calls) == {"0"}
+
     def test_explicit_number(self, tmp_path: Path):
         bash_proj, py_proj = _twin_projects(tmp_path)
         b = _run_bash("create-new-feature-branch.sh", bash_proj, "--json", "--number", "42", "some feature")