fix(scripts): keep PowerShell branch-name acronym match case-sensitive (parity with bash) (#3129)

* fix(scripts): keep PowerShell branch-name acronym match case-sensitive

Get-BranchName keeps a sub-3-character word only when it appears as an
UPPERCASE acronym in the description. The bash twin checks this
case-sensitively (grep "\b${word^^}\b" / grep -qw -- "${word^^}"), but the
PowerShell twin used -match, which is case-INSENSITIVE, so it kept EVERY
short word regardless of case -- contradicting its own comment and diverging
from bash. The same description then produced different spec-directory and
branch names on Windows/PowerShell vs macOS/Linux (e.g. "Add go support" ->
001-go-support instead of 001-support), desyncing specs/, feature.json, and
git branches across a mixed-OS team.

Use the case-sensitive -cmatch so a short word is kept only for a genuine
uppercase acronym, matching bash. Applied to both the core
scripts/powershell/create-new-feature.ps1 and the git extension's
create-new-feature-branch.ps1.

Add bash + PowerShell regression tests (core and git-extension) asserting a
lowercase short word is dropped while an uppercase acronym is kept.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test: fix article grammar in branch-name docstrings

Address review: 'an UPPERCASE acronym' -> 'an acronym in UPPERCASE' across the four branch-name case-sensitivity test docstrings (the indefinite article reads cleanly before 'acronym'). Docstring-only; no behavior change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -252,7 +252,10 @@ function Get-BranchName {
         if ($stopWords -contains $word) { continue }
         if ($word.Length -ge 3) {
             $meaningfulWords += $word
-        } elseif ($Description -match "\b$($word.ToUpper())\b") {
+        } elseif ($Description -cmatch "\b$($word.ToUpper())\b") {
+            # Case-sensitive (-cmatch) to mirror the bash twin's `grep -qw -- "${word^^}"`:
+            # keep a short word only when its UPPERCASE form appears in the original
+            # (an acronym). -match is case-insensitive and would keep every short word.
             $meaningfulWords += $word
         }
     }

tests/extensions/git/test_git_extension.py

@@ -298,6 +298,24 @@ class TestCreateFeatureBash:
         assert data["BRANCH_NAME"] == "001-user-auth"
         assert data["FEATURE_NUM"] == "001"
 
+    def test_branch_name_short_word_case_sensitivity(self, tmp_path: Path):
+        """A short word is dropped from the derived branch name unless it appears
+        as an acronym in UPPERCASE in the description (case-sensitive, must match the
+        PowerShell twin)."""
+        project = _setup_project(tmp_path)
+        # lowercase "go" (<3 chars, not an uppercase acronym) is dropped
+        r1 = _run_bash(
+            "create-new-feature-branch.sh", project, "--json", "--dry-run", "Add go support",
+        )
+        assert r1.returncode == 0, r1.stderr
+        assert json.loads(r1.stdout)["BRANCH_NAME"] == "001-support"
+        # uppercase "GO" is kept as an acronym
+        r2 = _run_bash(
+            "create-new-feature-branch.sh", project, "--json", "--dry-run", "Use GO now",
+        )
+        assert r2.returncode == 0, r2.stderr
+        assert json.loads(r2.stdout)["BRANCH_NAME"] == "001-use-go-now"
+
     def test_creates_branch_timestamp(self, tmp_path: Path):
         """Extension create-new-feature-branch.sh creates timestamp branch."""
         project = _setup_project(tmp_path)
@@ -426,6 +444,21 @@ class TestCreateFeaturePowerShell:
         data = json.loads(result.stdout)
         assert data["BRANCH_NAME"] == "001-user-auth"
 
+    def test_branch_name_short_word_case_sensitivity(self, tmp_path: Path):
+        """PowerShell must match the bash twin: a short word is dropped unless it
+        appears as an acronym in UPPERCASE (case-sensitive -cmatch, not -match)."""
+        project = _setup_project(tmp_path)
+        r1 = _run_pwsh(
+            "create-new-feature-branch.ps1", project, "-Json", "-DryRun", "Add go support",
+        )
+        assert r1.returncode == 0, r1.stderr
+        assert json.loads(r1.stdout)["BRANCH_NAME"] == "001-support"
+        r2 = _run_pwsh(
+            "create-new-feature-branch.ps1", project, "-Json", "-DryRun", "Use GO now",
+        )
+        assert r2.returncode == 0, r2.stderr
+        assert json.loads(r2.stdout)["BRANCH_NAME"] == "001-use-go-now"
+
     def test_dry_run_counts_branches_checked_out_in_worktrees(self, tmp_path: Path):
         """Branches checked out in sibling worktrees still reserve their prefix."""
         project = _setup_project(tmp_path / "project")

tests/test_timestamp_branches.py

@@ -240,6 +240,17 @@ class TestSequentialBranch:
         assert branch is not None
         assert re.match(r"^\d{3,}-new-feat$", branch), f"unexpected branch: {branch}"
 
+    def test_branch_name_short_word_case_sensitivity(self, git_repo: Path):
+        """A short word is dropped from the derived branch name unless it appears
+        as an acronym in UPPERCASE in the description. The PowerShell twin must use
+        case-sensitive -cmatch to produce the same result."""
+        r1 = run_script(git_repo, "--json", "--dry-run", "Add go support")
+        assert r1.returncode == 0, r1.stderr
+        assert json.loads(r1.stdout)["BRANCH_NAME"] == "001-support"
+        r2 = run_script(git_repo, "--json", "--dry-run", "Use GO now")
+        assert r2.returncode == 0, r2.stderr
+        assert json.loads(r2.stdout)["BRANCH_NAME"] == "001-use-go-now"
+
     def test_sequential_ignores_timestamp_dirs(self, git_repo: Path):
         """Sequential numbering skips timestamp dirs when computing next number."""
         (git_repo / "specs" / "002-first-feat").mkdir(parents=True)
@@ -272,6 +283,25 @@ class TestSequentialBranchPowerShell:
         assert "[long]::TryParse($matches[1], [ref]$num)" in content
         assert "$num = [int]$matches[1]" not in content
 
+    @pytest.mark.skipif(not _has_pwsh(), reason="pwsh not installed")
+    def test_branch_name_short_word_case_sensitivity(self, ps_git_repo: Path):
+        """Core create-new-feature.ps1 must drop a short word unless it appears as
+        an acronym in UPPERCASE (case-sensitive -cmatch), matching the bash twin."""
+        script = ps_git_repo / "scripts" / "powershell" / "create-new-feature.ps1"
+
+        def _run(desc: str) -> subprocess.CompletedProcess:
+            return subprocess.run(
+                ["pwsh", "-NoProfile", "-File", str(script), "-Json", "-DryRun", desc],
+                cwd=ps_git_repo, capture_output=True, text=True,
+            )
+
+        r1 = _run("Add go support")
+        assert r1.returncode == 0, r1.stderr
+        assert json.loads(r1.stdout)["BRANCH_NAME"] == "001-support"
+        r2 = _run("Use GO now")
+        assert r2.returncode == 0, r2.stderr
+        assert json.loads(r2.stdout)["BRANCH_NAME"] == "001-use-go-now"
+
 
 # ── check_feature_branch Tests ───────────────────────────────────────────────