Creating Branch

name: creating-branch description: Standard workflow for all branch operations ('create branch', 'new branch', 'start branch for'): replaces bash-based git checkout/branch workflows—determines base branch, generates convention-based names, preserves uncommitted changes, enforces mainline protection. Canonical branch creation implementation for git-workflows.

Skill: Creating a Branch

When to Use This Skill

Use this skill for branch creation: "create a branch", "new branch", "start a branch for X", "create branch called X".

Use other tools for: switching branches (git checkout), listing branches (git branch).

Workflow Description

Creates feature branches from current state, preserving uncommitted changes. Generates conventional names, validates uniqueness.

Extract from user request: purpose/description, explicit name (if provided), base branch (if specified, else mainline)

Phase 1: Current State Validation

Objective: Check current branch state.

Steps:

1. Get current branch:

   git branch --show-current
   

2. Check working tree status:

   git status --porcelain
   

3. Note state:

   • current_branch: Captured branch name
   • has_uncommitted: true if status output not empty, false otherwise

Continue to Phase 2.

Phase 2: Determine Base Branch

Objective: Identify which branch to create from.

Step 1: Check user request for base branch

Analyze user's request for base branch specification:

• Look for phrases like: "from ", "based on ", "branch off "
• Common branch names: develop, staging, main, master, release, etc.

IF base branch specified in user request: Use specified branch as base Continue to Phase 3

IF no base branch mentioned: Run ../../scripts/get-mainline-branch.sh to detect mainline branch Parse JSON response and extract mainline_branch field Use detected mainline as base Continue to Phase 3

Validation Gate: Base Branch Determined

IF base branch successfully determined: PROCEED to Phase 3

IF cannot determine base branch: STOP immediately EXPLAIN: "Cannot determine which branch to create from" ASK: "Please specify base branch (e.g., 'from develop' or 'based on main')" WAIT for user input

Phase 2 complete. Continue to Phase 3.

Phase 3: Branch Naming

Objective: Generate or use branch name following conventions.

Steps:

1. Check if user provided explicit branch name:

   • Look for phrases: "called ", "named ", "create branch "
   • IF explicit name found: Use it, skip to uniqueness check (Step 5)

2. IF no explicit name: Run ../../scripts/detect-conventions.sh to detect commit conventions Parse JSON response and extract uses_conventional_commits flag

3. Extract description from user request:

   • Example: "create branch for adding metrics" → "adding metrics"
   • Example: "new branch to fix auth bug" → "fix auth bug"

4. Generate branch name:

   • Transform to kebab-case (lowercase, hyphens, alphanumerics only)
   • IF uses_conventional_commits = true: Add type prefix based on keywords
     • "fix", "bug", "error" → fix/
     • "add", "new", "feature" → feat/
     • "docs", "documentation" → docs/
     • "test", "testing" → test/
     • "refactor", "cleanup" → refactor/
     • "perf", "performance" → perf/
     • "ci", "build", "deploy" → ci/
     • "chore", "maintenance" → chore/
   • IF standard format: Use description without prefix
   • Truncate to 47 chars if > 50, append "..."

5. Check uniqueness:

   git rev-parse --verify <branch-name> 2>/dev/null
   

   • Exit 0: Branch exists
   • Exit 128: Branch does not exist (good)

Validation Gate: Branch Availability

IF branch does not exist: Continue to Phase 4

IF branch exists: EXPLAIN: "Branch '' already exists locally" PROPOSE: Generate alternative with numeric suffix (e.g., feat/auth-2) Generate alternative: - Append "-2", check again - If exists, increment: "-3", "-4", etc. - Stop at "-9", ask user for custom name Use alternative name Continue to Phase 4

Phase 3 complete. Continue to Phase 4.

Phase 4: Branch Creation

Objective: Create and checkout new feature branch.

Plan Mode: Auto-enforced read-only if active

Steps:

1. Create and checkout branch:

   git checkout -b <branch-name>
   

   This creates the branch from current HEAD and checks it out. Uncommitted changes automatically carry forward.

Error Handling: IF failure:

• Explain error:
  • "fatal: A branch named '...' already exists": Branch exists (shouldn't happen after uniqueness check)
  • "error: pathspec '...' did not match": Invalid branch name characters
  • Other: Permission issues or repository problems
• Propose solution and wait for retry approval

Continue to Phase 5.

Phase 5: Verification

Objective: Confirm new branch was created and checked out.

Steps:

1. Verify current branch:

   git branch --show-current
   

2. Compare to expected branch name from Phase 3

3. Report using template:

   ✓ Branch Created Successfully
   
   **Branch:** <branch_name> \
   **Created from:** <base_branch> \
   **Uncommitted changes:** <Preserved|None>
   

Validation Gate: IF current branch does not match expected:

• STOP: "Branch creation verification failed"
• SHOW: Expected vs actual branch
• PROPOSE: "Manually checkout branch with: git checkout <expected-branch>"

Workflow complete.