chore(skill): add replan skill for iterative design and critique process

Author: mceachen

.claude/skills/replan/SKILL.md

@@ -0,0 +1,97 @@
+---
+name: replan
+description: Iterative deep planning with critiques and alternatives. Use when facing complex design decisions requiring thorough analysis.
+allowed-tools: Read, Glob, Grep, WebSearch, WebFetch
+---
+
+# Replan
+
+You are going to **replan** - an iterative process of designing, critiquing, and refining a plan.
+
+## Required Reading First
+
+Before any work, you MUST read:
+
+- [CLAUDE.md](CLAUDE.md)
+- [docs/SIMPLE-DESIGN.md](docs/SIMPLE-DESIGN.md)
+- [docs/TDD.md](docs/TDD.md)
+
+## Process
+
+### 1. Understand & Clarify
+
+- Read relevant code, documentation, and constraints
+- State any assumptions you're making
+- Ask clarifying questions before proceeding
+
+### 2. Initial Plan
+
+Design your first approach, considering requirements and existing solutions.
+
+### 3. Critique
+
+Generate thorough critiques of your plan:
+
+**General design:**
+
+- Does it balance simplicity with good engineering?
+- Is it maintainable, testable, DRY, scalable?
+- Scrutinize for "hand-wavy" aspects - don't assume how things work, study the code
+- For novel libraries/APIs, validate with web searches
+- Note uncertainties as risks
+
+**Project-specific:**
+
+- Does this preserve backwards compatibility for 500+ downstream consumers?
+- Does this affect ExifTool process pool performance or startup latency?
+- Does this handle timezone edge cases correctly (DST transitions, GPS inference, UTC deltas)?
+- Does this introduce new dependencies? Are they justified for a library this widely used?
+- Will this work cross-platform (Linux, macOS, Windows)?
+- Does this respect the auto-generated nature of Tags.ts (changes belong in mktags, not manual edits)?
+- Does the approach fail fast on errors rather than silently falling back to defaults?
+- Does this interact correctly with batch-cluster's process management?
+
+### 4. Alternatives
+
+Brainstorm alternatives based on critiques. Goals:
+
+- Simplify the plan
+- Reduce complexity and risk
+- Improve code quality and maintainability
+
+### 5. Develop Best Alternative
+
+Select the most promising alternative and develop it fully.
+
+### 6. Iterate
+
+Repeat steps 3-5 at least **three times**, asking for user feedback at each iteration.
+
+### 7. Final Plan
+
+Assemble the best features from all iterations into a robust final plan.
+
+## Output Format
+
+For each iteration, present options with pros/cons:
+
+### Option A: [Name]
+
+[Description]
+
+**Pros:** ...
+**Cons:** ...
+**Risks:** ...
+
+### Recommendation
+
+[Which option and why, per SIMPLE-DESIGN.md principles]
+
+## Guidelines
+
+- Follow Kent Beck's Four Rules of Simple Design as defined in docs/SIMPLE-DESIGN.md (in priority order: passes tests, reveals intention, no duplication, fewest elements, no bogus guardrails)
+- Consider coupling, cohesion, testability
+- Be honest about tradeoffs
+- Ask questions - don't guess
+- No mocks - plan for integration tests with real ExifTool and actual image files
+- Use `??` not `||`, `!= null` not `!`, standard `node:` imports