context-continuity-code

Original source / Raw SKILL.md

---
name: context-continuity-code
description: Claude Code-optimized context transfer for development workflows. Preserves code context, git state, running services, and development environment when moving work between sessions. Works seamlessly with peer review skills (Codex/Gemini). Use when transferring development work to a new Claude Code session.
---

# Context Continuity - Claude Code Edition

Transfer development context between Claude Code sessions with high fidelity, preserving code state, git context, and running services.

## Core Concept

When development work needs to transfer between Claude Code sessions, this skill creates structured artifacts that capture:

- **Code Context** - Files being worked on, functions/classes modified, pending changes
- **Git State** - Branch, commits, staged/unstaged changes, merge status
- **Environment State** - Running services, ports, environment variables, dependencies
- **Development Decisions** - Technical choices made, alternatives rejected, tradeoffs
- **Open Loops** - What's next, blockers, pending reviews

## When to Use This Skill

Use when you need to:
- Continue development work in a fresh Claude Code session
- Hand off work to another developer (with AI context preserved)
- Resume after context window fills (180K+ tokens)
- Switch between different Claude Code instances
- Document current state before major refactoring
- Prepare for peer review (Codex/Gemini integration)

**DO NOT use for:**
- General conversation summaries (use base context-continuity skill)
- Non-development contexts (writing, research, analysis)
- Simple task handoffs without code changes

## Workflow: Single Mode (Development-Optimized)

This skill uses a **single optimized mode** for development contexts (~400-600 words):

```markdown
═══════════════════════════════════════════════════════════════════
DEV CONTEXT TRANSFER
═══════════════════════════════════════════════════════════════════
Generated: [ISO timestamp] | Session: [ID if available]

**MISSION**: [What we're building/fixing + why it matters]

**STATUS**: [✓ complete | ⧗ in-progress | ⚠ blocked | ↻ iterating]

**PROGRESS**: [High-level summary of work completed this session]

───────────────────────────────────────────────────────────────────
§ CODE CONTEXT
───────────────────────────────────────────────────────────────────

**Active Files**:
- [file:line] - [What changed or what you're working on]
- [file:line] - [Status: implemented | in-progress | pending]

**Key Changes**:
- [Function/class]: [What changed + why]
- [Module/component]: [Refactoring/addition/fix]

**Code State**:
- Modified: [List files with uncommitted changes]
- Created: [New files added]
- Deleted: [Files removed]

───────────────────────────────────────────────────────────────────
§ GIT STATE
───────────────────────────────────────────────────────────────────

**Branch**: [current-branch-name]
**Base**: [main/master/develop]
**Commits**: [X commits ahead of base]

**Recent Commits**:
- [hash] [message]
- [hash] [message]

**Staged**: [Files in staging area | None]
**Unstaged**: [Modified files not staged | None]
**Untracked**: [New files not in git | None]

**Merge Status**: [Clean | Conflicts in X files | Pending PR #XXX]

───────────────────────────────────────────────────────────────────
§ ENVIRONMENT STATE
───────────────────────────────────────────────────────────────────

**Running Services**:
- [Service]: [localhost:PORT] - [Status: healthy | issue]
- [Database]: [postgres:5432] - [State: connected, X records]

**Dependencies**:
- Recently installed: [package@version, ...]
- Pending: [Packages needed but not installed]

**Environment Variables**:
- Critical vars set: [APP_ENV=dev, DATABASE_URL=localhost, ...]
- Missing/needed: [API_KEY (required for testing), ...]

**Terminal State**:
- Active shells: [X terminals open in /path/to/project]
- Background processes: [npm run dev, docker compose up, ...]

───────────────────────────────────────────────────────────────────
§ TECHNICAL DECISIONS
───────────────────────────────────────────────────────────────────

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| [Choice] | [Why] | [What we didn't do] | [Cost we're paying] |

**Architecture Notes**:
- [Pattern/approach chosen]: [Why it fits this context]
- [Constraint observed]: [Technical/business reason]

**Peer Review Integration**:
- Codex consulted: [Yes/No] - [If yes: key recommendations]
- Gemini consulted: [Yes/No] - [If yes: key recommendations]
- Agreements: [Where both AIs aligned]
- Disagreements: [Where perspectives differed + our choice]

───────────────────────────────────────────────────────────────────
§ OPEN LOOPS
───────────────────────────────────────────────────────────────────

**Next Actions**:
- [ ] [Immediate next step - be specific]
- [ ] [Following step]

**Blockers**:
- [What's blocking + why]: [Waiting for X | Need to solve Y]

**Pending**:
- Code review: [PR #XXX awaiting review]
- Testing: [Need to test X scenario]
- Documentation: [Need to update README/docs]

**Questions to Resolve**:
- [ ] [Technical question needing answer]
- [ ] [Design decision pending]

───────────────────────────────────────────────────────────────────
§ TESTING & VALIDATION
───────────────────────────────────────────────────────────────────

**Test Status**:
- Passing: [X/Y tests pass]
- Failing: [Test names that fail + why]
- Coverage: [X% coverage | Not measured]

**Manual Testing Done**:
- [Scenario tested]: [Result]
- [Edge case checked]: [Outcome]

**Still Need to Test**:
- [ ] [Test case pending]
- [ ] [Integration scenario]

───────────────────────────────────────────────────────────────────
§ CONTEXT NOTES
───────────────────────────────────────────────────────────────────

**Key Insights**:
- [Important discovery from this session]
- [Gotcha/caveat to remember]

**Developer Notes**:
- Communication style: [Preferences for next session]
- Assumed knowledge: [What doesn't need re-explaining]
- Sensitive areas: [Code that's fragile, requires care]

**Links/References**:
- Documentation: [URLs to relevant docs]
- Related PRs/Issues: [GitHub links]
- Design docs: [Figma, diagrams, etc.]

═══════════════════════════════════════════════════════════════════
§ TRANSFER READY
═══════════════════════════════════════════════════════════════════
Review for accuracy before sharing. Check git state and file paths.
```

**After generating, ask:**
"Before you transfer—are there any sections that need further detail or refinement?"

---

## Generating the Artifact

### Step 1: Gather Context

**File Context**:
```bash
# Get modified files
git status --short

# Get recent commits
git log --oneline -5

# Check current branch and tracking
git branch -vv

# Show uncommitted changes summary
git diff --stat
git diff --cached --stat
```

**Environment Context**:
```bash
# Check running processes
lsof -i -P -n | grep LISTEN

# Check environment
env | grep -E '(PATH|NODE_ENV|DATABASE|API|APP_)'

# Recent package changes (if applicable)
git log --oneline -10 package.json
```

**Code Context**:
- Note which files have been actively edited
- Identify key functions/classes modified
- Track new files created vs existing files changed

### Step 2: Generate Artifact

Fill out sections systematically:
1. **Mission/Status/Progress** - What and why
2. **Code Context** - What files/functions changed
3. **Git State** - Branch, commits, staging area
4. **Environment State** - Services, dependencies, env vars
5. **Technical Decisions** - Choices made (include peer review input)
6. **Open Loops** - Next actions, blockers
7. **Testing** - What's validated, what's pending
8. **Context Notes** - Insights, gotchas, references

### Step 3: Present & Refine

1. Present artifact in full
2. Add: "§ TRANSFER READY—Review for accuracy before sharing."
3. Ask: "Before you transfer, are there any sections that need further detail or refinement?"
4. Human reviews, requests expansions if needed

### Step 4: Transfer to New Session

**Receiving agent prompt** (optional prepend):
```
[DEV CONTEXT TRANSFER]

The following is a development context transfer from a previous Claude Code session.

After reading, provide a handshake confirmation:

"I've reviewed the dev context. Quick confirmation:
- Mission: [Echo back what we're building]
- Code State: [Active files and key changes]
- Git: [Branch + commit status]
- Next: [Immediate next action]
- Environment: [Critical services/dependencies]

Ready to [next action]. What's your priority?"
```

---

## Integration with Peer Review Skills

When using Codex or Gemini for peer review **during** the development session:

### Before Peer Review

1. Generate a lightweight context artifact (just Code + Git + Technical Decisions sections)
2. Use as input to peer review request
3. Get Codex/Gemini perspective

### After Peer Review

1. Update § Technical Decisions with peer review findings:
   - What Codex/Gemini recommended
   - Where they agreed
   - Where they disagreed
   - Which advice you followed (and why)

2. Include in transfer artifact so receiving agent knows:
   - What external validation was done
   - What technical debates were resolved
   - What alternatives were already considered

### Example Integration

```markdown
§ TECHNICAL DECISIONS

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| Use Redis for session storage | Sub-ms latency required, peer reviews validated | PostgreSQL (too slow), In-memory (no persistence) | Added infrastructure complexity |

**Peer Review Integration**:
- **Codex consulted**: Yes - Recommended Redis over Postgres for session store, flagged potential memory limits
- **Gemini consulted**: Yes - Agreed with Redis choice, suggested Redis Cluster for scaling
- **Agreements**: Both AIs validated Redis for performance needs
- **Disagreements**: Codex suggested 1GB limit, Gemini suggested 2GB - we chose 1.5GB as middle ground
- **Implementation notes**: Added eviction policy (allkeys-lru) based on Codex warning about memory pressure
```

---

## Best Practices

**Do:**
- Run `git status` and `git diff --stat` before generating
- Include specific file paths with line numbers (file.py:123)
- Note running services and their ports
- Capture peer review insights in § Technical Decisions
- Include error messages or test failures verbatim
- Mark files as "in-progress" vs "completed"

**Don't:**
- Include secrets, API keys, credentials (redact them)
- Paste entire file contents (link to files with line ranges)
- Assume receiving agent has access to same environment
- Skip git state (critical for resuming work)
- Forget to note running services (easy to miss)

---

## Examples

See `references/examples.md` for:
- Full-stack feature development handoff
- Bug fix mid-investigation transfer
- Refactoring session continuation
- Code review preparation
- Post-peer-review implementation
- Emergency context capture

---

## Validation

Use the Python validator to check artifact quality:

```bash
python context-continuity-code/scripts/validate_dev_transfer.py artifact.md
```

Checks for:
- Required sections present
- Git state completeness
- File paths formatted correctly
- No secrets leaked
- Peer review integration (if applicable)

---

## Design Principles

**Development-First**: Optimized for code handoffs, not general conversation
**Git-Aware**: Git state is mandatory, not optional
**Tool State Required**: Environment and services are core context
**Peer Review Integration**: First-class support for Codex/Gemini consultation
**Single Mode**: One format optimized for dev workflows (no Minimal/Full choice)
**Antifragile**: Critical info first (Mission → Code → Git → Environment)

---

## Differences from Base Context Continuity

| Feature | Base Skill | Claude Code Edition |
|---------|-----------|---------------------|
| Target | General conversations | Development work only |
| Modes | Minimal + Full | Single optimized mode |
| Tool State | Optional [T] tags | Mandatory §§ sections |
| Git Context | Not included | Required |
| Code Context | Not included | Core feature |
| Peer Review | Not mentioned | Integrated workflow |
| Length | 200-1000 words | 400-600 words |
| Environment | Any Claude instance | Claude Code only |

---

Use this skill when resuming development work. Use base `context-continuity` for general conversations.


---

## Referenced Files

> The following files are referenced in this skill and included for context.

### references/examples.md

```markdown
# Development Context Transfer Examples

Real-world scenarios showing how to transfer development context between Claude Code sessions.

---

## Example 1: API Endpoint Implementation (Mid-Development)

**Scenario:** Building a new REST API endpoint, halfway done, need to continue in fresh session.

```markdown
═══════════════════════════════════════════════════════════════════
DEV CONTEXT TRANSFER
═══════════════════════════════════════════════════════════════════
Generated: 2025-11-16T15:30:00Z | Session: api-dev-001

**MISSION**: Implement POST /api/users endpoint with validation and database persistence

**STATUS**: ⧗ in-progress

**PROGRESS**: Request validation implemented and tested. Database integration pending.

───────────────────────────────────────────────────────────────────
§ CODE CONTEXT
───────────────────────────────────────────────────────────────────

**Active Files**:
- src/routes/users.js:45-120 - POST endpoint implemented, validation done
- src/validators/userValidator.js:10-35 - Schema validation complete
- tests/routes/users.test.js:50-85 - 3 validation tests passing

**Key Changes**:
- createUser handler: Request parsing, validation working
- userValidator: Joi schema for email, password, name
- Tests: Validation edge cases covered

**Code State**:
- Modified: src/routes/users.js, src/validators/userValidator.js
- Created: tests/routes/users.test.js
- Deleted: None

───────────────────────────────────────────────────────────────────
§ GIT STATE
───────────────────────────────────────────────────────────────────

**Branch**: feature/user-creation-endpoint
**Base**: main
**Commits**: 2 commits ahead of main

**Recent Commits**:
- f7a3b2e Add user validation schema with Joi
- c4d9e1f Implement POST /api/users route handler

**Staged**: src/validators/userValidator.js, tests/routes/users.test.js
**Unstaged**: src/routes/users.js (still adding DB integration)
**Untracked**: None

**Merge Status**: Clean (no conflicts)

───────────────────────────────────────────────────────────────────
§ ENVIRONMENT STATE
───────────────────────────────────────────────────────────────────

**Running Services**:
- Express API: localhost:3000 - healthy, auto-reloading with nodemon
- PostgreSQL: localhost:5432 - connected as dev_user, database: app_dev
- Redis: localhost:6379 - connected, empty (not used yet)

**Dependencies**:
- Recently installed: [email protected], [email protected]
- Pending: None

**Environment Variables**:
- Critical vars set: NODE_ENV=development, DATABASE_URL=postgresql://localhost:5432/app_dev
- Missing/needed: None

**Terminal State**:
- Active shells: 2 terminals (1 running nodemon, 1 for git/testing)
- Background processes: nodemon server.js, postgres

───────────────────────────────────────────────────────────────────
§ TECHNICAL DECISIONS
───────────────────────────────────────────────────────────────────

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| Use Joi for validation | Team standard, good error messages | Yup (less familiar), manual validation (error-prone) | Added 50KB dependency |
| Hash passwords with bcrypt | Industry standard, well-tested | Argon2 (newer, less adoption), plain hashing (insecure) | Slower (intentional for security) |

**Architecture Notes**:
- Following existing REST API patterns in codebase
- Validation middleware approach consistent with other endpoints

**Peer Review Integration**:
- Codex consulted: No (straightforward implementation)
- Gemini consulted: No

───────────────────────────────────────────────────────────────────
§ OPEN LOOPS
───────────────────────────────────────────────────────────────────

**Next Actions**:
- [ ] Add database insert logic in src/routes/users.js:95-110
- [ ] Hash password with bcrypt before storing
- [ ] Add error handling for duplicate emails (unique constraint)
- [ ] Write tests for successful user creation
- [ ] Add integration test with actual database

**Blockers**: None

**Pending**:
- Code review: Will create PR after DB integration complete
- Testing: Need to test happy path + duplicate email case
- Documentation: Update API docs with new endpoint

**Questions to Resolve**:
- [ ] Should we return user with hashed password or exclude it? (Ask team)

───────────────────────────────────────────────────────────────────
§ TESTING & VALIDATION
───────────────────────────────────────────────────────────────────

**Test Status**:
- Passing: 3/3 validation tests pass
- Failing: None (DB tests not written yet)
- Coverage: 85% for validation, 0% for DB integration

**Manual Testing Done**:
- curl POST with valid data: validation passes
- curl POST with invalid email: correct 400 error
- curl POST with missing fields: correct 400 error

**Still Need to Test**:
- [ ] Successful user creation (with DB)
- [ ] Duplicate email handling
- [ ] Password hashing verification
- [ ] Response format matches API spec

───────────────────────────────────────────────────────────────────
§ CONTEXT NOTES
───────────────────────────────────────────────────────────────────

**Key Insights**:
- Joi error messages are very user-friendly, good UX
- Need to remember to exclude password from response

**Developer Notes**:
- Communication style: Code-first, prefer working examples
- Assumed knowledge: Express, PostgreSQL, REST API design
- Sensitive areas: Password hashing logic (must get right)

**Links/References**:
- API Spec: https://docs.example.com/api/users
- Database Schema: db/migrations/001_create_users.sql

═══════════════════════════════════════════════════════════════════
§ TRANSFER READY
═══════════════════════════════════════════════════════════════════
Review for accuracy before sharing. Check git state and file paths.
```

**Receiving Agent Handshake:**
```
I've reviewed the dev context. Quick confirmation:
- Mission: Implementing POST /api/users endpoint with validation and DB persistence
- Code State: Validation complete (users.js:45-120, userValidator.js), DB integration pending
- Git: feature/user-creation-endpoint, 2 commits ahead of main, no conflicts
- Next: Add DB insert logic, hash password with bcrypt, handle duplicate emails
- Environment: Express on :3000, PostgreSQL on :5432 connected, nodemon running

Ready to add database integration. What's your priority?
```

---

## Example 2: Bug Fix with Peer Review Integration

**Scenario:** Memory leak investigation, consulted Codex and Gemini, ready to implement fix.

```markdown
═══════════════════════════════════════════════════════════════════
DEV CONTEXT TRANSFER
═══════════════════════════════════════════════════════════════════
Generated: 2025-11-16T16:45:00Z | Session: bugfix-memleak-003

**MISSION**: Fix memory leak in image processing worker (heap grows 2GB/hour under load)

**STATUS**: ⧗ in-progress - Root cause identified via peer review, fix ready to implement

**PROGRESS**: Leak source pinpointed to buffer handling in processImage(). Codex and Gemini both confirmed diagnosis. Fix approach validated.

───────────────────────────────────────────────────────────────────
§ CODE CONTEXT
───────────────────────────────────────────────────────────────────

**Active Files**:
- workers/imageWorker.js:82-110 - Memory leak is here (buffer.slice() copying)
- tests/leak-detection.test.js:15-45 - Reproduces leak reliably

**Key Changes**:
- processImage function: Identified buffer.slice() creating copies not GC'd
- Leak detection test: Demonstrates 2GB growth after 1000 iterations

**Code State**:
- Modified: workers/imageWorker.js (added debug logging, not committed)
- Created: tests/leak-detection.test.js
- Deleted: None

───────────────────────────────────────────────────────────────────
§ GIT STATE
───────────────────────────────────────────────────────────────────

**Branch**: bugfix/image-worker-memory-leak
**Base**: main
**Commits**: 1 commit ahead

**Recent Commits**:
- a9b8c7d Add leak detection test (currently failing as expected)

**Staged**: tests/leak-detection.test.js
**Unstaged**: workers/imageWorker.js (has debug logging to remove)
**Untracked**: None

**Merge Status**: Clean

───────────────────────────────────────────────────────────────────
§ ENVIRONMENT STATE
───────────────────────────────────────────────────────────────────

**Running Services**:
- Worker process: Running with --expose-gc flag for testing
- Redis queue: localhost:6379 - 0 jobs in queue (testing mode)

**Dependencies**:
- Recently installed: [email protected] (for heap profiling)
- Pending: None

**Environment Variables**:
- Critical vars set: NODE_ENV=test, NODE_OPTIONS=--expose-gc
- Missing/needed: None

**Terminal State**:
- Active shells: 3 (worker, heap profiler, git)
- Background processes: Redis, heap snapshot running

───────────────────────────────────────────────────────────────────
§ TECHNICAL DECISIONS
───────────────────────────────────────────────────────────────────

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| Use buffer.subarray() instead of slice() | Peer review validated, subarray shares memory | Keep slice (leaks memory), Copy + explicit free (complex) | Must ensure buffer lifecycle management |
| Add explicit null assignment after use | Peer review recommendation for GC hints | Rely on auto GC (unreliable with closures) | Slightly more verbose code |

**Architecture Notes**:
- Buffer lifecycle was unclear due to closure capturing buffer reference
- Peer review illuminated the hidden copy behavior of slice()

**Peer Review Integration**:
- **Codex consulted**: Yes - Identified buffer.slice() as culprit at line 87
  - Recommendation: Use subarray() and explicit null after processing
  - Warning: Subarray shares memory, ensure original buffer not mutated

- **Gemini consulted**: Yes - Confirmed Codex diagnosis independently
  - Recommendation: subarray() + WeakMap for tracking buffer lifecycle
  - Alternative suggestion: Use buffer pools for reuse

- **Agreements**: Both identified slice() copy behavior as root cause
- **Disagreements**:
  - Codex: Simple subarray() + null (minimal change)
  - Gemini: Add WeakMap tracking (more infrastructure)
  - **Our choice**: Codex approach (simpler, sufficient for this case)

- **Implementation plan** (validated by both AIs):
  1. Replace slice() with subarray() at line 87
  2. Add null assignment at line 109 after processing
  3. Add comment explaining memory sharing with subarray()
  4. Verify with leak detection test (heap should stay flat)

───────────────────────────────────────────────────────────────────
§ OPEN LOOPS
───────────────────────────────────────────────────────────────────

**Next Actions**:
- [ ] Replace buffer.slice() with buffer.subarray() at line 87
- [ ] Add `processedBuffer = null` at line 109
- [ ] Remove debug logging added during investigation
- [ ] Run leak detection test (should pass now)
- [ ] Run full test suite
- [ ] Heap profile for 10K iterations to confirm fix

**Blockers**: None

**Pending**:
- Code review: Will tag @sarah for security review (buffer handling)
- Testing: Need to run under production load simulation
- Documentation: Add comment explaining subarray() memory behavior

**Questions to Resolve**: None (peer review answered all questions)

───────────────────────────────────────────────────────────────────
§ TESTING & VALIDATION
───────────────────────────────────────────────────────────────────

**Test Status**:
- Passing: 24/25 tests pass
- Failing: leak-detection.test.js (expected - demonstrates bug)
- Coverage: 89%

**Manual Testing Done**:
- Heap profiling: Confirmed 2GB leak over 1 hour
- Chrome DevTools: Buffer count grows linearly with requests
- Flame graph: Time spent in slice() increasing over time

**Still Need to Test**:
- [ ] Leak fixed (heap stays flat after 10K iterations)
- [ ] No functional regression (images processed correctly)
- [ ] Performance impact (subarray should be faster than slice)
- [ ] Production load simulation (1000 req/sec for 10 minutes)

───────────────────────────────────────────────────────────────────
§ CONTEXT NOTES
───────────────────────────────────────────────────────────────────

**Key Insights**:
- slice() creates a copy, subarray() shares memory - critical difference
- Closures can prevent GC even when buffer appears out of scope
- Peer review caught this faster than we would have manually

**Developer Notes**:
- Communication style: Technical detail appreciated
- Assumed knowledge: Node.js buffers, memory management, profiling
- Sensitive areas: Buffer handling is critical path, changes must be verified

**Links/References**:
- Node Buffer docs: https://nodejs.org/api/buffer.html#bufsubarray
- Codex review: /tmp/codex-memleak-review.txt
- Gemini review: /tmp/gemini-memleak-review.txt
- Heap snapshots: ./heap-snapshots/*.heapsnapshot

═══════════════════════════════════════════════════════════════════
§ TRANSFER READY
═══════════════════════════════════════════════════════════════════
Peer review consensus: subarray() + null assignment. Ready to implement.
```

---

## Example 3: Refactoring Session (Code Review Prep)

**Scenario:** Refactoring authentication module before submitting for code review.

```markdown
═══════════════════════════════════════════════════════════════════
DEV CONTEXT TRANSFER
═══════════════════════════════════════════════════════════════════
Generated: 2025-11-16T14:20:00Z | Session: refactor-auth-002

**MISSION**: Refactor authentication module to extract middleware and improve testability

**STATUS**: ✓ complete - Refactoring done, tests passing, ready for code review

**PROGRESS**: Extracted 3 middleware functions, added dependency injection, increased test coverage from 60% to 92%. All tests passing.

───────────────────────────────────────────────────────────────────
§ CODE CONTEXT
───────────────────────────────────────────────────────────────────

**Active Files**:
- src/auth/authService.js:1-220 - Refactored with DI, 4 methods extracted
- src/middleware/authMiddleware.js:1-85 - NEW: Extracted middleware (verifyToken, requireAuth, requireRole)
- tests/auth/authService.test.js:1-180 - Coverage 60% → 92%
- tests/middleware/authMiddleware.test.js:1-95 - NEW: Middleware tests

**Key Changes**:
- authService: Added constructor injection for dependencies (redis, jwt, db)
- Extracted 3 middleware to separate file for reusability
- Tests: Added dependency mocking, edge case coverage

**Code State**:
- Modified: src/auth/authService.js, tests/auth/authService.test.js
- Created: src/middleware/authMiddleware.js, tests/middleware/authMiddleware.test.js
- Deleted: None

───────────────────────────────────────────────────────────────────
§ GIT STATE
───────────────────────────────────────────────────────────────────

**Branch**: refactor/auth-service-di
**Base**: main
**Commits**: 4 commits ahead

**Recent Commits**:
- e3f2a1b Extract auth middleware to separate module
- b7c4d9e Add dependency injection to AuthService
- a8b5c3d Increase test coverage with edge cases
- d2e9f1a Add middleware unit tests

**Staged**: All changes staged (ready for PR)
**Unstaged**: None
**Untracked**: None

**Merge Status**: Clean (rebased on latest main)

───────────────────────────────────────────────────────────────────
§ ENVIRONMENT STATE
───────────────────────────────────────────────────────────────────

**Running Services**:
- Express API: localhost:3000 - healthy
- PostgreSQL: localhost:5432 - connected
- Redis: localhost:6379 - connected, 0 sessions (test mode)

**Dependencies**:
- Recently installed: None (using existing dependencies)
- Pending: None

**Environment Variables**:
- Critical vars set: NODE_ENV=test, JWT_SECRET=test-secret
- Missing/needed: None

**Terminal State**:
- Active shells: 2 (test watcher, git)
- Background processes: jest --watch

───────────────────────────────────────────────────────────────────
§ TECHNICAL DECISIONS
───────────────────────────────────────────────────────────────────

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| Constructor injection for DI | Testability, explicit dependencies | Service locator (hidden deps), global singletons (untestable) | Slightly more boilerplate |
| Extract middleware to separate file | Reusability, SRP | Keep in authService (mixed concerns), Inline in routes (duplication) | More files to maintain |
| Keep backward compatibility | Don't break existing code | Break everything, force migration (risky) | Some deprecated code paths |

**Architecture Notes**:
- Following dependency injection pattern used in other services
- Middleware extraction makes them usable in any Express app
- Maintained backward compat by keeping old factory function as wrapper

**Peer Review Integration**:
- Codex consulted: No (straightforward refactoring)
- Gemini consulted: No

───────────────────────────────────────────────────────────────────
§ OPEN LOOPS
───────────────────────────────────────────────────────────────────

**Next Actions**:
- [ ] Create PR with description of changes
- [ ] Request review from @alex (auth expert)
- [ ] Update documentation with DI examples

**Blockers**: None

**Pending**:
- Code review: PR to be created
- Documentation: Need to update README with DI usage
- Migration guide: Optional, for teams using old pattern

**Questions to Resolve**: None

───────────────────────────────────────────────────────────────────
§ TESTING & VALIDATION
───────────────────────────────────────────────────────────────────

**Test Status**:
- Passing: 45/45 tests pass (100% pass rate)
- Failing: None
- Coverage: 92% (up from 60% before refactoring)

**Manual Testing Done**:
- Login flow: Works with new DI pattern
- Token refresh: Verified with Postman
- Role-based access: Tested admin/user/guest roles

**Still Need to Test**: None (all scenarios covered)

───────────────────────────────────────────────────────────────────
§ CONTEXT NOTES
───────────────────────────────────────────────────────────────────

**Key Insights**:
- DI made testing much easier (can mock Redis, DB without test containers)
- Middleware extraction revealed some duplication we can eliminate later

**Developer Notes**:
- Communication style: Prefer refactoring incrementally
- Assumed knowledge: DI patterns, Express middleware, testing with mocks
- Sensitive areas: Auth logic is security-critical, changes must be careful

**Links/References**:
- Original issue: https://github.com/company/repo/issues/245
- DI pattern doc: docs/architecture/dependency-injection.md

═══════════════════════════════════════════════════════════════════
§ TRANSFER READY
═══════════════════════════════════════════════════════════════════
All tests passing. Ready to create PR for code review.
```

---

## Example 4: Quick Emergency Fix

**Scenario:** Production bug fix in progress, need to switch machines.

```markdown
═══════════════════════════════════════════════════════════════════
DEV CONTEXT TRANSFER
═══════════════════════════════════════════════════════════════════
Generated: 2025-11-16T18:30:00Z | Session: hotfix-prod-bug

**MISSION**: Fix critical production bug - API returning 500 for /api/products when category is null

**STATUS**: ⚠ blocked - Fix identified but needs database migration, awaiting DBA approval

**PROGRESS**: Root cause found (missing null check in category join). Fix ready but requires DB migration to add default category.

───────────────────────────────────────────────────────────────────
§ CODE CONTEXT
───────────────────────────────────────────────────────────────────

**Active Files**:
- src/queries/products.js:45-50 - Added null check for category_id
- db/migrations/003_add_default_category.sql:1-10 - NEW: Migration script

**Key Changes**:
- getProductsWithCategory query: Added LEFT JOIN with null handling
- Migration: Adds "Uncategorized" default category

**Code State**:
- Modified: src/queries/products.js
- Created: db/migrations/003_add_default_category.sql
- Deleted: None

───────────────────────────────────────────────────────────────────
§ GIT STATE
───────────────────────────────────────────────────────────────────

**Branch**: hotfix/products-category-null
**Base**: production
**Commits**: 1 commit ahead

**Recent Commits**:
- f9e8d7c Add null check for category in products query

**Staged**: src/queries/products.js, db/migrations/003_add_default_category.sql
**Unstaged**: None
**Untracked**: None

**Merge Status**: Clean (based on production branch)

───────────────────────────────────────────────────────────────────
§ ENVIRONMENT STATE
───────────────────────────────────────────────────────────────────

**Running Services**:
- Local API: localhost:3000 - testing fix locally
- Local PostgreSQL: localhost:5432 - test data loaded

**Dependencies**:
- Recently installed: None
- Pending: None

**Environment Variables**:
- Critical vars set: NODE_ENV=development, DATABASE_URL=localhost
- Missing/needed: Production DB credentials (don't have access)

**Terminal State**:
- Active shells: 2 (API server, psql for testing)
- Background processes: nodemon

───────────────────────────────────────────────────────────────────
§ TECHNICAL DECISIONS
───────────────────────────────────────────────────────────────────

**Decisions Made**:
| Decision | Rationale | Alternatives Rejected | Tradeoff |
|----------|-----------|----------------------|----------|
| LEFT JOIN with null handling | Preserve products with no category | Filter them out (loses data), Throw error (bad UX) | Migration required |
| Add default "Uncategorized" category | Better UX than empty category | Show null (confusing), Skip category field (breaks API contract) | Data migration needed |

**Architecture Notes**:
- Bug exists because products table allows null category_id but query assumes non-null
- Migration adds default category and updates null values

**Peer Review Integration**:
- Codex consulted: No (straightforward SQL fix)
- Gemini consulted: No

───────────────────────────────────────────────────────────────────
§ OPEN LOOPS
───────────────────────────────────────────────────────────────────

**Next Actions**:
- [ ] Get DBA approval for migration (Slack sent to @maria)
- [ ] Run migration on production (after approval)
- [ ] Deploy code fix
- [ ] Verify fix in production
- [ ] Monitor for similar issues

**Blockers**:
- **DBA approval**: Waiting for @maria to approve migration (Slack sent 30 min ago)
- **Production access**: Need VPN + production DB credentials to apply migration

**Pending**:
- Testing: Local testing done, production test pending
- Monitoring: Need to verify fix resolves production errors

**Questions to Resolve**:
- [ ] Should we backfill all null categories or just future ones? (Asked DBA)

───────────────────────────────────────────────────────────────────
§ TESTING & VALIDATION
───────────────────────────────────────────────────────────────────

**Test Status**:
- Passing: All existing tests pass
- Failing: None
- Coverage: Not changed (hotfix, no new test coverage)

**Manual Testing Done**:
- Local API: Products with null category now return with category="Uncategorized"
- Local DB: Migration runs cleanly on test database
- Postman: GET /api/products returns 200 (was 500 before fix)

**Still Need to Test**:
- [ ] Production deployment (after migration)
- [ ] Production API returns 200 for affected products

───────────────────────────────────────────────────────────────────
§ CONTEXT NOTES
───────────────────────────────────────────────────────────────────

**Key Insights**:
- Bug was introduced in PR #789 when we allowed null categories
- Need to add constraint or validation to prevent null categories in future

**Developer Notes**:
- Communication style: Urgent, production issue
- Assumed knowledge: SQL, database migrations, production deploy process
- Sensitive areas: Production database - must get DBA approval before changes

**Links/References**:
- Production error logs: https://logs.example.com/api-500-errors
- Original PR that introduced bug: https://github.com/company/repo/pull/789
- Slack thread with DBA: https://company.slack.com/archives/C123/p1234567890

═══════════════════════════════════════════════════════════════════
§ TRANSFER READY
═══════════════════════════════════════════════════════════════════
Blocked on DBA approval. Migration script ready. Code fix tested locally.
```

---

## Key Patterns Across Examples

### Complete vs In-Progress vs Blocked

**Status symbols guide receiving agent's approach:**
- `✓ complete` - Review, create PR, document
- `⧗ in-progress` - Continue implementation
- `⚠ blocked` - Work around blocker or wait
- `↻ iterating` - Refining approach

### Git State Detail

Always include:
- Current branch name
- Number of commits ahead
- Staged vs unstaged vs untracked distinction
- Merge status (clean, conflicts, pending PR)

### Peer Review Integration

When consulting Codex or Gemini:
```markdown
**Peer Review Integration**:
- Codex: [What asked | Key findings | Recommendations]
- Gemini: [What asked | Key findings | Recommendations]
- Agreements: [Where both aligned]
- Disagreements: [Where perspectives differed]
- **Our choice**: [What we decided + why]
```

### Environment State

Critical for resuming work:
- Running services with ports
- Database connections and state
- Environment variables (redact secrets!)
- Background processes

### Code Context Specificity

Use file:line references:
- `auth.js:145-180` - specific range being worked on
- `userValidator.js:35` - exact line with issue
- Status markers: `implemented | in-progress | pending`

---

Use these examples as templates for your own development context transfers!

```