[Spec Kit] Implementation progress

.specify/extensions/git/scripts/bash/git-common.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# Git-specific common functions for the git extension.
+# Extracted from scripts/bash/common.sh — contains only git-specific
+# branch validation and detection logic.
+
+# Check if we have git available at the repo root
+has_git() {
+    local repo_root="${1:-$(pwd)}"
+    { [ -d "$repo_root/.git" ] || [ -f "$repo_root/.git" ]; } && \
+        command -v git >/dev/null 2>&1 && \
+        git -C "$repo_root" rev-parse --is-inside-work-tree >/dev/null 2>&1
+}
+
+# Strip a single optional path segment (e.g. gitflow "feat/004-name" -> "004-name").
+# Only when the full name is exactly two slash-free segments; otherwise returns the raw name.
+spec_kit_effective_branch_name() {
+    local raw="$1"
+    if [[ "$raw" =~ ^([^/]+)/([^/]+)$ ]]; then
+        printf '%s\n' "${BASH_REMATCH[2]}"
+    else
+        printf '%s\n' "$raw"
+    fi
+}
+
+# Validate that a branch name matches the expected feature branch pattern.
+# Accepts sequential (###-* with >=3 digits) or timestamp (YYYYMMDD-HHMMSS-*) formats.
+# Logic aligned with scripts/bash/common.sh check_feature_branch after effective-name normalization.
+check_feature_branch() {
+    local raw="$1"
+    local has_git_repo="$2"
+
+    # For non-git repos, we can't enforce branch naming but still provide output
+    if [[ "$has_git_repo" != "true" ]]; then
+        echo "[specify] Warning: Git repository not detected; skipped branch validation" >&2
+        return 0
+    fi
+
+    local branch
+    branch=$(spec_kit_effective_branch_name "$raw")
+
+    # Accept sequential prefix (3+ digits) but exclude malformed timestamps
+    # Malformed: 7-or-8 digit date + 6-digit time with no trailing slug (e.g. "2026031-143022" or "20260319-143022")
+    local is_sequential=false
+    if [[ "$branch" =~ ^[0-9]{3,}- ]] && [[ ! "$branch" =~ ^[0-9]{7}-[0-9]{6}- ]] && [[ ! "$branch" =~ ^[0-9]{7,8}-[0-9]{6}$ ]]; then
+        is_sequential=true
+    fi
+    if [[ "$is_sequential" != "true" ]] && [[ ! "$branch" =~ ^[0-9]{8}-[0-9]{6}- ]]; then
+        echo "ERROR: Not on a feature branch. Current branch: $raw" >&2
+        echo "Feature branches should be named like: 001-feature-name, 1234-feature-name, or 20260319-143022-feature-name" >&2
+        return 1
+    fi
+
+    return 0
+}