claude-code/plugins/swarm-coordination/skills/swarm-patterns/references/checkpoint-flow.md

Checkpoint-Based Orchestration

A phased approach to swarm execution that prevents conflicts through planning, review, and controlled implementation.

Overview

Checkpoint-based orchestration separates swarm execution into distinct phases:

1. Planning - Agents analyze and plan (read-only)
2. Review - Orchestrator detects conflicts
3. Resolution - Conflicts resolved before implementation
4. Claiming - Files assigned to agents
5. Implementation - Agents execute plans
6. Verification - Results validated

Why Checkpoints?

Without Checkpoints

Launch agents → Agents work in parallel → CONFLICT! →
Agents overwrite each other → Endless fix loops → Chaos

With Checkpoints

Launch planning agents → Collect plans → Detect conflicts →
Resolve conflicts → Claim files → Sequential/parallel execution → Success

Phase Details

Phase 1: Planning (Parallel, Read-Only)

Purpose: Gather implementation plans without making changes

Key Rules:

• Agents may READ any file
• Agents must NOT WRITE any file
• Each agent produces a structured plan

Agent Instructions:

You are in PLANNING MODE. Analyze the codebase and create an implementation plan.

CRITICAL RESTRICTIONS:
- DO NOT use Edit, Write, or any file modification tools
- DO NOT execute commands that modify files
- ONLY use Read, Glob, Grep for analysis

Your output must be a structured plan listing:
- All files you need to modify (with full paths)
- All files you need to create
- All files you need to delete
- Dependencies on other components
- Step-by-step implementation approach

Plan Format:

## Agent Plan: [agent-id]

### Task Summary
[1-2 sentence description of what this agent will accomplish]

### Files to Modify
- `src/auth/handler.ts`: Add validateToken() function and update handleRequest()
- `src/types/auth.ts`: Add TokenPayload interface

### Files to Create
- `src/auth/tokens.ts`: Token generation and validation utilities

### Files to Delete
- `src/auth/legacy-auth.ts`: Replaced by new implementation

### Dependencies
- **Requires**: Database schema must include users table
- **Blocks**: API routes cannot be updated until auth is complete

### Implementation Steps
1. Create TokenPayload interface in types
2. Implement token utilities in new file
3. Update handler with validation logic
4. Remove legacy file after verification

### Estimated Scope
- Files touched: 4
- Lines added: ~150
- Lines removed: ~80
- Risk level: Medium (touching auth system)

Phase 2: Conflict Detection

Purpose: Identify overlapping file edits before they happen

Process:

1. Collect all agent plans
2. Build file → agent mapping
3. Identify conflicts:
   • Same file modified by multiple agents
   • Delete conflicts with modify
   • Creation conflicts
   • Dependency cycles

Conflict Types:

Type	Severity	Example
Same file modify	Critical	agent-1 and agent-2 both modify handler.ts
Create collision	Critical	Both agents create utils/helper.ts
Delete + Modify	Critical	agent-1 deletes file agent-2 modifies
Dependency cycle	Critical	agent-1 waits for agent-2, agent-2 waits for agent-1
Same directory	Warning	Both agents add files to src/utils/
Import chain	Info	agent-1's file imports from agent-2's file

Phase 3: Resolution

Purpose: Resolve all conflicts before implementation begins

Resolution Strategies:

Sequential Execution:

Conflict: agent-1 and agent-2 both modify src/api/index.ts

Resolution: Execute sequentially
- Execution order: agent-1 first, then agent-2
- agent-2 will see agent-1's changes before starting

Scope Reassignment:

Conflict: agent-1 (auth) and agent-2 (logging) both modify middleware.ts

Resolution: Reassign to single agent
- Expand agent-1's scope to include logging changes
- Remove middleware.ts from agent-2's plan

File Splitting:

Conflict: agent-1 and agent-2 both modify large config.ts

Resolution: Split the file
- Create config/auth.ts (agent-1)
- Create config/db.ts (agent-2)
- Update config/index.ts to re-export

User Decision:

Conflict: Complex dependency between agent-1 and agent-3

Resolution: Present to user
"Agents 1 and 3 have interleaved dependencies. Options:
1. Merge into single agent
2. Manual sequencing with intermediate reviews
3. Redesign the task split"

Phase 4: File Claiming

Purpose: Register file ownership before implementation

Process:

1. For each resolved plan, register claims
2. Update .claude/file-claims.md
3. Determine execution batches

Execution Order Determination:

Given resolved plans:
- agent-1: No dependencies
- agent-2: No dependencies
- agent-3: Depends on agent-1
- agent-4: Depends on agent-2 and agent-3

Execution order:
Batch 1 (parallel): agent-1, agent-2
Batch 2 (after batch 1): agent-3
Batch 3 (after agent-3): agent-4

Phase 5: Implementation with Monitoring

Purpose: Execute plans with status tracking

Process:

1. Launch batch 1 agents
2. Start polling loop (every 30-60 seconds)
3. As agents complete:
   • Release their file claims
   • Launch dependent agents
4. Handle issues as detected:
   • Stuck agents → investigate/reassign
   • Conflicts → pause and resolve
   • Failures → report and decide

Agent Instructions for Implementation:

You are now in IMPLEMENTATION MODE. Execute your approved plan.

Your approved plan is in: .claude/swarm-plans/[your-agent-id].md
Your claimed files are in: .claude/file-claims.md

RULES:
1. Only modify files that are claimed by YOUR agent ID
2. Follow your plan exactly - do not expand scope
3. If you need to modify an unclaimed file, STOP and report
4. Update progress by completing your assigned tasks

Phase 6: Verification

Purpose: Validate swarm completed successfully

Checks:

• All agents reported completion
• All planned files were modified
• No orphaned file claims
• Build succeeds (if applicable)
• Tests pass (if applicable)
• No unexpected files modified

Checkpoint Gates

Each phase has a gate that must pass before proceeding:

Gate	Condition	Failure Action
Planning → Review	All planning agents completed	Wait or timeout
Review → Resolution	Conflict report generated	Re-run detection
Resolution → Claiming	All conflicts resolved	Return to resolution
Claiming → Implementation	All files claimed, no overlaps	Fix claim issues
Implementation → Verification	All agents completed	Investigate failures
Verification → Complete	All checks pass	Fix issues or report

State Machine

┌─────────────┐
│ INITIALIZED │
└──────┬──────┘
       │ Start swarm
       ▼
┌─────────────┐
│  PLANNING   │◄────────────────┐
└──────┬──────┘                 │
       │ All plans received     │
       ▼                        │
┌─────────────┐                 │
│  REVIEWING  │                 │
└──────┬──────┘                 │
       │ Conflicts identified   │
       ▼                        │
┌─────────────┐                 │
│  RESOLVING  │─────────────────┘
└──────┬──────┘  Need re-plan
       │ All resolved
       ▼
┌─────────────┐
│  CLAIMING   │
└──────┬──────┘
       │ Files assigned
       ▼
┌─────────────┐
│IMPLEMENTING │◄───┐
└──────┬──────┘    │
       │           │ Next batch
       ▼           │
┌─────────────┐    │
│  VERIFYING  │────┘
└──────┬──────┘  More batches
       │ All verified
       ▼
┌─────────────┐
│  COMPLETED  │
└─────────────┘

Benefits

1. No Conflicts: Detected and resolved before implementation
2. Visibility: Know exactly what each agent will do
3. Control: Orchestrator maintains full oversight
4. Recovery: Can roll back or adjust between phases
5. Efficiency: Parallel execution where safe, sequential where needed