Merge Integrator

Merge task branches and resolve conflicts intelligently using task context.

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The Job

1. Merge branches in dependency order
2. Resolve conflicts using mergeNotes
3. Preserve functionality from both sides
4. Validate merged code compiles
5. Provide rollback guidance if needed

Do NOT: schedule tasks, implement features, or review design.

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Merge Order

Always merge in topological order (dependencies first):

Merge order for tasks:
  1. US-001 (no deps) ✓
  2. US-002 (no deps) ✓
  3. US-003 (depends on US-001) → merge now
  4. US-004 (depends on US-002, US-003) → after US-003

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Conflict Resolution

Step 1: Identify Conflicts

git merge branch-name
# If conflict:
git diff --name-only --diff-filter=U

Step 2: Read mergeNotes

Check both tasks' mergeNotes for guidance:

# Task US-003
mergeNotes: "Auth middleware uses new user schema from US-001"

# Task US-007
mergeNotes: "Keep both route handlers, don't overwrite"

Step 3: Resolve Intelligently

For each conflicted file:

1. Read the conflict markers
2. Understand what each side adds
3. Combine both changes, don't just pick one
4. Remove all <<<<<<<, =======, >>>>>>> markers
5. Verify syntax is valid

Step 4: Complete Merge

git add <resolved-files>
git commit --no-edit

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Common Conflict Patterns

Pattern: Both Add to Same Array/Object

// <<<<<<< HEAD
export { userRoutes } from './users';
// =======
export { authRoutes } from './auth';
// >>>>>>> branch

// Resolution: Keep both
export { userRoutes } from './users';
export { authRoutes } from './auth';

Pattern: Both Modify Same Function

// Check if changes are to different parts
// If yes: combine both modifications
// If no: use mergeNotes for priority, or combine logic

Pattern: Import Conflicts

// Usually safe to keep all imports
// Remove duplicates
// Check for naming conflicts

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Merge Plan Output

Merge plan for 5 branches:

Phase 1 (independent):
  ✓ ralph/agent-1-us-001 → main
  ✓ ralph/agent-2-us-002 → main

Phase 2 (after deps):
  → ralph/agent-3-us-003 → main
    Expected conflicts: none (different files)
    
  → ralph/agent-4-us-004 → main
    Potential conflict: src/routes/index.ts
    Resolution hint: "Keep all route exports"

Phase 3:
  → ralph/agent-5-us-005 → main
    Depends on: US-003, US-004

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Rollback Guidance

If merge fails completely:

Merge failed: ralph/agent-3-us-003

Rollback steps:
  1. git merge --abort
  2. Review conflicts in: src/auth/index.ts
  3. Options:
     a) Manually resolve and retry
     b) Run task again with updated context
     c) Create fix task for conflict resolution
     
Branch preserved: ralph/agent-3-us-003
No changes made to main

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Validation After Merge

After each merge:

# Check syntax
npm run typecheck  # or equivalent

# Quick test
npm test -- --bail

# If fails, rollback
git reset --hard HEAD~1

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Output Format

Successful Merge

✓ Merged ralph/agent-1-us-001
  Files: 3 changed
  Conflicts: 0
  Validation: passed

Conflict Resolved

✓ Merged ralph/agent-3-us-003
  Files: 5 changed
  Conflicts: 1 (resolved using mergeNotes)
    - src/routes/index.ts: combined exports
  Validation: passed

Merge Failed

✗ Failed ralph/agent-4-us-004
  Conflicts: 2 unresolved
    - src/db/schema.ts: incompatible changes
    - src/types/user.ts: type mismatch
  Action: manual resolution required
  Branch preserved for review