Surgical Contributor (Minimal Diff PR Skill)

Surgical Contributor

Overview

Execute a disciplined contribution loop: reproduce, isolate, patch minimally, and protect against regressions.

Optimize for:

• Mergeability
• Trust
• Behavior stability

Core Principles

These principles govern all decisions:

• Think before coding: do not assume; surface uncertainty early
• Simplicity first: prefer the smallest solution that fully solves the problem
• Surgical changes: touch only what is required for the fix
• Goal-driven execution: define success via reproduction and verification

If uncertain:

• state assumptions explicitly
• prefer clarification over guessing
• choose the safer, narrower change

Contribution Doctrine

Apply this doctrine in every run:

• Regression-first
• Minimal-diff
• Maintainer-friendly

Refuse these by default unless explicitly requested:

• Broad refactors
• Speculative architecture shifts
• Opportunistic style rewrites
• Feature expansion beyond the bug or paper cut

What “Surgical” Means in Practice

• Only modify the minimal set of files and lines required
• Do not change unrelated code, comments, or formatting
• Match existing patterns and conventions
• Do not introduce abstractions unless strictly necessary
• If a smaller patch works, prefer it

Every changed line must trace directly to the identified problem.

Operating Modes

Choose exactly one mode at the start of work:

1. Bugfix mode
   Reproduce a correctness issue, isolate root cause, apply narrow patch, add regression protection.

2. Paper-cut mode
   Fix high-frequency UX friction in hot paths with minimal behavioral surface area.

3. Refactor-under-permission mode
   Only when explicitly requested; keep each change independently safe and reviewable.

4. Review-my-own-PR mode
   Perform a strict maintainer-style critique before final output (no code changes).

Non-code repository fallback

If no executable bug exists, treat the repository as a specification system.

Fix exactly one deterministic weakness:

• ambiguity
• missing constraint
• contradiction
• scope leak
• unenforceable rule

Use the smallest reviewable documentation patch.

Standard Workflow

1. Find one pain point

Select one issue that is:

• Reproducible
• Narrow in scope
• High-value

Prefer:

• State/caching bugs
• Edge-case crashes
• UI-backend drift
• Startup/config issues
• Hot-path UX friction

Stack-Specific Focus

When working in UI-heavy or stateful codebases, prioritize issues where small state mistakes create disproportionate user impact.

Focus areas:

• State synchronization bugs
• Cache invalidation errors
• Selection / batch operation drift
• Undo/redo inconsistencies
• UI-backend contract mismatches
• Interaction edge cases (keyboard, focus, timing)

These bugs often:

• have small fixes
• but high user impact
• and low review resistance when isolated correctly

When available, consult:

• references/risk-map.md

Use it during:

• target selection
• self-review

2. Write a tiny change plan before editing

Document:

• Observed behavior
• Expected behavior
• Suspected root cause
• Safest seam to modify
• Risk surface

State assumptions explicitly if any uncertainty exists.

3. Reproduce first

Create a minimal repro:

• Existing test
• New focused test
• Small harness
• Manual repro if needed

Do not fix before proving the failure.

4. Implement the narrowest safe fix

Rules:

• No unrelated cleanup
• Preserve all non-bug behavior
• Prefer local fixes over rewrites
• Avoid new abstractions unless required
• Keep code as simple as possible

If two solutions exist, choose the simpler one.

5. Add regression protection

Add exactly one durable protection:

• Automated test (preferred)
• Focused harness
• Manual verification protocol

Tie directly to the reproduced issue.

6. Run self-review before finalizing

Checklist:

• Is behavior outside the bug unchanged?
• Are state and cache flows still consistent?
• Are edge cases still safe?
• Are UI/interaction flows intact?
• Is platform behavior safe (if relevant)?
• Is naming consistent with the repo?
• Is this the smallest viable patch?

7. Produce maintainer-language PR summary

Use this exact structure:

## What broke


## Root cause


## Why this fix is minimal


## What I tested


## What I intentionally did not change