fix: derive paths-only branch from feature directory

scripts/bash/common.sh

@@ -151,6 +151,9 @@ get_feature_paths() {
 
     # Use printf '%q' to safely quote values, preventing shell injection
     # via crafted branch names or paths containing special characters
+    if [[ -z "$current_branch" ]]; then
+        current_branch="$(basename "$feature_dir")"
+    fi
     printf 'REPO_ROOT=%q\n' "$repo_root"
     printf 'CURRENT_BRANCH=%q\n' "$current_branch"
     printf 'FEATURE_DIR=%q\n' "$feature_dir"

scripts/powershell/common.ps1

@@ -139,6 +139,14 @@ function Get-FeaturePathsEnv {
         [Console]::Error.WriteLine("ERROR: Feature directory not found. Set SPECIFY_FEATURE_DIRECTORY or run the specify command to create .specify/feature.json.")
         exit 1
     }
+
+    if (-not $currentBranch) {
+        $normalizedFeatureDir = $featureDir.TrimEnd(
+            [System.IO.Path]::DirectorySeparatorChar,
+            [System.IO.Path]::AltDirectorySeparatorChar
+        )
+        $currentBranch = Split-Path -Path $normalizedFeatureDir -Leaf
+    }
 
     [PSCustomObject]@{
         REPO_ROOT     = $repoRoot

tests/test_check_prerequisites_paths_only.py

@@ -141,6 +141,26 @@ def test_paths_only_text_mode_on_non_spec_branch(prereq_repo: Path) -> None:
     assert "FEATURE_DIR:" in result.stdout
 
 
+@requires_bash
+def test_paths_only_falls_back_to_feature_dir_basename(prereq_repo: Path) -> None:
+    """--paths-only should emit a non-empty branch name from feature.json."""
+    feat = prereq_repo / "specs" / "001-my-feature"
+    feat.mkdir(parents=True, exist_ok=True)
+    _write_feature_json(prereq_repo)
+    script = prereq_repo / ".specify" / "scripts" / "bash" / "check-prerequisites.sh"
+    result = subprocess.run(
+        ["bash", str(script), "--json", "--paths-only"],
+        cwd=prereq_repo,
+        capture_output=True,
+        text=True,
+        check=False,
+        env=_clean_env(),
+    )
+    assert result.returncode == 0, result.stderr
+    data = json.loads(result.stdout)
+    assert data["BRANCH"] == "001-my-feature"
+
+
 @requires_bash
 def test_normal_mode_still_validates_branch(prereq_repo: Path) -> None:
     """Without --paths-only, feature directory validation must still fail on main."""
@@ -211,6 +231,27 @@ def test_ps_paths_only_succeeds_on_spec_branch(prereq_repo: Path) -> None:
     assert "FEATURE_DIR" in data
 
 
+@pytest.mark.skipif(not (HAS_PWSH or _WINDOWS_POWERSHELL), reason="no PowerShell available")
+def test_ps_paths_only_falls_back_to_feature_dir_basename(prereq_repo: Path) -> None:
+    """-PathsOnly should emit a non-empty branch name from feature.json."""
+    feat = prereq_repo / "specs" / "001-my-feature"
+    feat.mkdir(parents=True, exist_ok=True)
+    _write_feature_json(prereq_repo)
+    script = prereq_repo / ".specify" / "scripts" / "powershell" / "check-prerequisites.ps1"
+    exe = "pwsh" if HAS_PWSH else _WINDOWS_POWERSHELL
+    result = subprocess.run(
+        [exe, "-NoProfile", "-File", str(script), "-Json", "-PathsOnly"],
+        cwd=prereq_repo,
+        capture_output=True,
+        text=True,
+        check=False,
+        env=_clean_env(),
+    )
+    assert result.returncode == 0, result.stderr
+    data = json.loads(result.stdout)
+    assert data["BRANCH"] == "001-my-feature"
+
+
 @pytest.mark.skipif(not (HAS_PWSH or _WINDOWS_POWERSHELL), reason="no PowerShell available")
 def test_ps_normal_mode_still_validates_branch(prereq_repo: Path) -> None:
     """Without -PathsOnly, feature directory validation must still fail on main."""