Jujutsu VCS Integration: PoC Plan

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Jujutsu VCS Integration Proof of Concept Plan

๐Ÿš€ Executive Summary

Goal: Guys, let's figure out if Jujutsu VCS integration can actually make things better for our Agentic QE Fleet before we jump in headfirst.

Approach: We're going to use evidence, manage risks, and take things one step at a time. Timeline: 2 weeks for the PoC, then a decision point. If it's a go, we're looking at a 12-week full implementation. Budget: 80 hours (one engineer for two weeks).

๐Ÿ“Š Baseline Metrics (Current System)

System State (as of 2025-11-15)

  • Total Test Files: 1,256
  • QE Agents: 102 agent definitions
  • Monthly Commits: 142 commits (last 30 days)
  • Version Control: Git (the usual)
  • No VCS abstraction layer
  • No concurrent agent workspace isolation

Current Pain Points (TO BE VALIDATED)

  • โ“ Agent workspace conflicts (how often?)
  • โ“ Git staging overhead (how long does it take?)
  • โ“ Concurrent execution bottlenecks (do they even happen?)
  • โ“ Conflict resolution time (what's the baseline? We need to know!)

IMPORTANT: We absolutely need to measure these things before we can say anything is better.

๐ŸŽฏ Phase 1: Proof of Concept (2 Weeks)

Week 1: Installation & Validation

Day 1-2: Environment Setup

Goal: Get Jujutsu working in our world.

Tasks:

[ ] Install Jujutsu via package manager
[ ] Test basic jj commands in DevPod
[ ] Install agentic-jujutsu crate
[ ] Verify WASM bindings compile
[ ] Test basic WASM operations

Success Criteria:

  • โœ… Jujutsu CLI works in DevPod
  • โœ… WASM bindings compile without errors
  • โœ… Can create/commit/query changes via WASM

Failure Exit: If the WASM bindings don't work, we stop, document the problems, and report what we found.

Day 3-5: Performance Baseline

Goal: Compare how fast Git is versus Jujutsu.

Benchmark Tests:

// Test 1: Create workspace
measure(() => git.clone(repo))
measure(() => jj.init(repo))

// Test 2: Commit changes
measure(() => {
  git.add('.');
  git.commit('message');
})
measure(() => {
  jj.commit('message'); // Auto-staging
})

// Test 3: Concurrent operations
measure(() => {
  // 3 agents editing simultaneously
  git.branch('agent-1'); git.checkout('agent-1');
  git.branch('agent-2'); git.checkout('agent-2');
  git.branch('agent-3'); git.checkout('agent-3');
})
measure(() => {
  // 3 Jujutsu workspaces
  jj.workspace.create('agent-1');
  jj.workspace.create('agent-2');
  jj.workspace.create('agent-3');
})

// Test 4: Conflict scenarios
// Create intentional conflicts, measure resolution time

Deliverable: A performance report with REAL numbers.

Example Output:

## Performance Benchmark Results

| Operation         | Git (ms) | Jujutsu (ms) | Improvement | 
| ----------------- | -------- | ------------ | ----------- | 
| Create workspace  | 450ms    | 120ms        | 3.75x faster | 
| Commit changes    | 85ms     | 15ms         | 5.67x faster | 
| 3 concurrent workspaces | 1,200ms  | 180ms        | 6.67x faster | 
| Resolve conflict (auto) | N/A      | 450ms        | New capability | 

**Overall**: 4-7x performance improvement in tested scenarios
**Caveat**: Tested on DevPod with sample repo (50MB)

Week 2: Integration Prototype

Day 6-8: Minimal VCS Adapter

Goal: Build the simplest abstraction layer possible.

Code:

// /src/vcs/base-adapter.ts
interface VCSAdapter {
  commit(message: string): Promise<void>;
  createWorkspace(name: string): Promise<Workspace>;
  getCurrentChanges(): Promise<Change[]>;
}

// /src/vcs/jujutsu-adapter.ts
class JujutsuAdapter implements VCSAdapter {
  // Minimal implementation using agentic-jujutsu
}

// /src/vcs/git-adapter.ts
class GitAdapter implements VCSAdapter {
  // Wrapper around existing Git calls
}

Success Criteria:

  • โœ… Both adapters implement the same interface.
  • โœ… Tests pass for both implementations.
  • โœ… Can swap adapters via config.

Day 9-10: Single Agent Integration

Goal: Test with ONE agent (qe-test-generator).

Integration:

// Modify qe-test-generator to use VCS adapter
const adapter = VCSAdapterFactory.create(); // Auto-detect
await adapter.createWorkspace('test-gen-workspace');
await generateTests();
await adapter.commit('Generated tests for UserService');

Test Scenarios:

  1. Generate tests with Git adapter โ†’ measure time.
  2. Generate tests with Jujutsu adapter โ†’ measure time.
  3. Run 3 concurrent test generations โ†’ measure conflicts.

Success Criteria:

  • โœ… Agent works with both adapters.
  • โœ… Jujutsu shows measurable performance improvement.
  • โœ… No breaking changes to the existing workflow.

๐Ÿ“ˆ Success Metrics (Evidence-Based)

Minimum Viable Success (PoC)

We need these to move to Phase 2:

Metric Target Measurement
WASM Bindings Work 100% Can execute jj commands via WASM
Performance Improvement โ‰ฅ2x Benchmarked commit/workspace operations
No Breaking Changes 0 Existing tests still pass
Single Agent Integration Works qe-test-generator uses adapter

Decision Rule:

  • โœ… ALL metrics met โ†’ Proceed to Phase 2 (full implementation).
  • โš ๏ธ Performance <2x โ†’ Re-evaluate: Is it worth it?
  • โŒ WASM doesn't work โ†’ Stop, document, and close the issue.

Stretch Goals (Nice to Have)

  • Concurrent workspace isolation working.
  • Auto-commit reducing overhead by >50%.
  • Conflict detection API functional.

โš ๏ธ Risk Assessment (Data-Driven)

Risk Matrix

Risk Probability Impact Mitigation
WASM bindings fail in DevPod Medium High Test in Week 1 Day 1, exit early if fails
Performance <2x improvement Medium Medium Measure in Week 1, decide if worth continuing
Jujutsu API changes (pre-1.0) High Medium Pin version, document API used
Integration complexity Low Low Start with 1 agent, keep it simple
Team learning curve Low Low Optional feature, comprehensive docs

Mitigation Strategies

Technical Risks:

  • Pin agentic-jujutsu version in package.json.
  • Feature flag to disable if issues arise.
  • Git fallback always available.
  • Minimal changes to existing code.

Adoption Risks:

  • Make it opt-in via .aqe-ci.yml.
  • Document both Git and Jujutsu workflows.
  • Internal dogfooding before external release.

๐Ÿ“‹ Deliverables (Evidence Required)

Week 1 Deliverables

[ ] Installation report (works/doesn't work)
[ ] Performance benchmarks (with real numbers)
[ ] WASM compatibility report
[ ] Go/No-Go decision document

Week 2 Deliverables

[ ] VCS adapter code (base + 2 implementations)
[ ] Single agent integration (qe-test-generator)
[ ] Test results (adapter tests + integration tests)
[ ] Final recommendation report

Final PoC Report Template

## Jujutsu VCS PoC - Final Report

### Executive Summary

*   PoC Goal: Validate Jujutsu performance and feasibility
*   Outcome: [Success / Partial Success / Failure]
*   Recommendation: [Proceed / Revisit / Abandon]

### Measured Results

| Claim                  | Actual Result | Evidence                     | 
| ---------------------- | ------------- | ---------------------------- | 
| "23x faster"          | X.Xx faster   | Benchmark: tests/vcs-benchmark.ts | 
| "95% conflict reduction" | Not tested    | N/A                          | 
| "WASM works in DevPod" | [Yes/No]      | Installation log             | 

### Blockers Encountered

1.  [Issue description + resolution/workaround]

### Lessons Learned

1.  [What worked well]
2.  [What didn't work]
3.  [Unexpected findings]

### Recommendation

[Detailed reasoning for proceed/stop decision]

### Next Steps (if proceeding)

[Specific actions for Phase 2]

๐Ÿš€ Phase 2: Full Implementation (IF PoC Succeeds)

Timeline: 12 weeks (not 4 weeks - a realistic estimate). Scope: Extend to all 18 QE agents.

Week 3-6: Adapter Layer (4 weeks)

  • Complete VCS abstraction layer.
  • Implement all operations (commit, merge, rebase, log).
  • Add operation logging to AgentDB.
  • 90%+ test coverage.
  • Documentation.

Week 7-10: Agent Integration (4 weeks)

  • Extend to all 18 QE agents (1-2 agents/week).
  • Add workspace isolation per agent.
  • Implement concurrent execution tests.
  • Performance validation across all agents.

Week 11-12: Configuration & Rollout (2 weeks)

  • Add .aqe-ci.yml VCS configuration.
  • Feature flags for gradual rollout.
  • Documentation (setup, migration, troubleshooting).
  • Internal dogfooding.
  • Beta release announcement.

Week 13-14: Monitoring & Iteration (2 weeks)

  • Monitor production usage.
  • Collect feedback.
  • Fix bugs.
  • Performance tuning.
  • Case study documentation.

Total: 14 weeks (PoC + Implementation)

๐Ÿ’ฐ Cost-Benefit Analysis

Investment

  • PoC: 80 hours (2 weeks ร— 1 engineer)
  • Full Implementation (if approved): 480 hours (12 weeks ร— 1 engineer)
  • Total: 560 hours

Expected Benefits (IF claims are validated)

Measured after PoC:

  • Performance improvement: X.Xx faster (TBD).
  • Workspace isolation: Yes/No (TBD).
  • Auto-commit savings: Y% overhead reduction (TBD).

Theoretical benefits (cannot validate until full implementation):

  • Conflict reduction: Unknown (requires AI conflict resolution).
  • Cost savings: Unknown (requires learning system).
  • Audit trail: Yes (Jujutsu operation log exists).

Break-Even Analysis

If PoC shows 2x improvement:

  • Time saved per pipeline: ~5 seconds (estimated).
  • Pipelines per day: ~20 (estimated).
  • Time saved per day: 100 seconds = 1.67 minutes.
  • Time saved per week: 8.35 minutes.
  • Break-even: ~670 weeks (12+ years).

If PoC shows 5x improvement:

  • Time saved per pipeline: ~15 seconds.
  • Break-even: ~250 weeks (5 years).

If PoC shows 10x improvement:

  • Time saved per pipeline: ~35 seconds.
  • Break-even: ~110 weeks (2 years).

Conclusion: This is a long-term investment, not a quick win.

๐ŸŽฏ Decision Framework

After Week 1 (Go/No-Go Decision Point)

Proceed to Week 2 if:

  • โœ… WASM bindings work in DevPod.
  • โœ… Performance improvement โ‰ฅ2x.
  • โœ… No major blockers discovered.

Stop if:

  • โŒ WASM bindings don't work.
  • โŒ Performance <1.5x (marginal gain, high effort).
  • โŒ Major blocker (API instability, compatibility).

After Week 2 (Full Implementation Decision)

Proceed to Phase 2 if:

  • โœ… PoC fully successful (all success criteria met).
  • โœ… Performance improvement โ‰ฅ4x (justifies 12-week investment).
  • โœ… Single agent integration works flawlessly.
  • โœ… Team capacity available (1 engineer for 12 weeks).

Defer if:

  • โš ๏ธ Performance 2-4x (good but not great).
  • โš ๏ธ Higher priority features exist.
  • โš ๏ธ Team capacity constrained.

Abandon if:

  • โŒ PoC failed to meet minimum criteria.
  • โŒ Performance <2x.
  • โŒ Integration too complex.

๐Ÿ“š Research & References

Jujutsu VCS

agentic-jujutsu

Comparison with Original Proposal (Issue #47)

Aspect Original Claim This Plan
Timeline 4 weeks 2 weeks PoC + 12 weeks implementation
Performance "23x faster" Measure in PoC, don't promise
Scope 18 agents + AI + learning 1 agent in PoC, expand if successful
Success criteria Vague ("learning improves") Measurable (โ‰ฅ2x perf, WASM works)
Risk assessment Underestimated Realistic with exit points

๐Ÿšฆ Next Steps

Immediate (This Week)

  1. Review this plan with stakeholders.
  2. Approve 2-week PoC budget (80 hours).
  3. Assign engineer to PoC work.
  4. Set up tracking (PoC kanban board).

Week 1 PoC Kickoff

  1. Install Jujutsu in DevPod.
  2. Test WASM bindings.
  3. Run performance benchmarks.
  4. Document findings.

Decision Points

  • End of Week 1: Go/No-Go for Week 2
  • End of Week 2: Proceed/Defer/Abandon Phase 2

๐Ÿ“ž Contact & Questions

PoC Lead: TBD Stakeholders: Product, Engineering, QE Escalation: If blockers arise, escalate immediately (don't wait 2 weeks).

Created: 2025-11-15 Status: Awaiting Approval Next Review: End of Week 1 (PoC)