Context Engineering: Implement Phase (Enhanced)

When invoked, execute the approved implementation plan chunk by chunk:

Key Innovation: Inter-Phase Awareness

This implement phase KNOWS:

• RPI-Plan structured chunks for atomic implementation
• Each CHUNK-Pn contains a complete, ordered todolist
• Chunk dependencies dictate execution order
• Marking chunks complete updates both plan AND research documents
• Context reset is needed after every 3 chunks or 35% utilization

Prerequisites

• Approved plan at .claude/plans/active/[feature]_plan.md
• Plan contains chunk manifest with chunk-todolists
• If not found, run /context-eng:plan $ARGUMENTS first

Golden Rules

ONE CHUNK → COMPLETE TODOLIST → MARK DONE → NEXT CHUNK
ONE TODO → ONE CHANGE → ONE TEST → ONE COMMIT

Chunk-Based Implementation Loop

FOR each CHUNK-Pn in dependency_order:
  IF dependencies_complete:
    1. Load CHUNK-Pn todolist
    
    FOR each TODO in todolist:
      a. Make atomic change
      b. Run todo-specific test
      c. If PASS: commit, mark TODO ✅
      d. If FAIL: STOP, investigate, fix
    END TODO LOOP
    
    2. Update chunk documentation
    3. Mark CHUNK-Pn as IMPLEMENTED
    4. Update research CHUNK-Rn to IMPLEMENTED
    
    IF chunks_processed % 3 == 0 OR context > 35%:
      Context reset (save progress, reload plan)
    END IF
    
    5. Proceed to next ready chunk
  END IF
END CHUNK LOOP

Process

1. Load Plan Document
   • Read .claude/plans/active/[feature]_plan.md
   • Extract chunk manifest and dependency graph
   • Verify plan status is APPROVED
2. Determine Execution Order Based on chunk dependency graph:
   • Independent chunks first (parallel capable)
   • Dependent chunks in order
   • Final chunks (e.g., test additions)

3. For Each Chunk (in dependency order):

   a. Check dependencies complete

   b. Execute each todo atomically:

   • Make single change
   • Run specified test
   • If pass: commit with message
   • If fail: STOP, investigate, fix

   c. After all todos complete:

   • Mark CHUNK-Pn as IMPLEMENTED
   • Update CHUNK-Rn in research to IMPLEMENTED
   • Commit chunk documentation updates

   d. Context management:

   • After every 3 chunks: reload plan
   • If >35% utilization: save, compact, continue
4. Run Full Test Suite After all chunks complete
5. Documentation Updates (MANDATORY)
   • Check CODE_TO_WORKFLOW_MAP.md for affected workflows
   • Update workflow files with new line numbers
   • Update function signatures if changed
6. Context Reset (Every 3 Chunks)
   • Update chunk progress in plan
   • Re-read plan document
   • Verify scope alignment
   • Compact if >35% utilization
7. Finalize
   • Move plan to .claude/plans/completed/
   • Move research to .claude/research/completed/
   • Run /context-eng:validate to verify

Chunk Status Updates

Update Plan Document

| Chunk | Status | Todos Done | Commit | Research Updated |
|-------|--------|------------|--------|------------------|
| P1 | ✅ IMPLEMENTED | 4/4 | abc123 | ✅ R1 |
| P2 | ▶️ IMPLEMENTING | 2/5 | - | - |

Update Research Document

Mark each CHUNK-Rn status:

• FOUND → COMPLETE → PLANNED → IMPLEMENTED

Error Handling

Commit Format

Per-todo:

feat(chunk-Pn): Todo N - description
Implements: [feature] chunk N

Per-chunk completion:

feat(chunk-Pn): Complete chunk - [domain]
Completes: CHUNK-Pn, Updates: CHUNK-Rn

Context Budget

• Plan: 15k tokens
• Active code (per chunk): ~10k tokens
• Test results (per chunk): ~5k tokens
• Max active (3 chunks): ~45k tokens (22.5%)