feat: add pre-pr-checks skill for Claude Code

.claude/skills/pre-pr-checks.md

@@ -0,0 +1,82 @@
+---
+name: pre-pr-checks
+description: "Pre-PR checks for ai-sdk-go. Runs license headers, lint, and unit tests matching the CI pipeline (task ci)."
+---
+
+# Pre-PR Checks — ai-sdk-go
+
+Run these before pushing changes or creating a PR.
+
+## Quick Check (all CI steps)
+
+```bash
+task ci
+```
+
+This runs: `license:check` → `lint` → `test:unit` (matches CI exactly).
+
+## Individual Steps
+
+### 1. License Headers
+
+```bash
+# Check
+task license:check
+
+# Auto-fix (add missing headers)
+task license
+```
+
+### 2. Lint
+
+```bash
+# Full lint with auto-fix
+task lint
+
+# Only new issues (faster, what the Stop hook runs)
+task lint:new
+```
+
+Common lint rules that catch people:
+- **wsl_v5** — requires blank lines before `if`, `return`, and between declarations and logic
+- **funcorder** — constructors must appear before methods on the same struct
+- **gocritic** — catches duplicate branch bodies, unnecessary conversions, etc.
+
+### 3. Tests
+
+```bash
+# Unit tests only (fast, no API keys needed) — this is what CI runs
+task test:unit
+
+# Single package
+go test ./providers/openai/ -short -count=1 -v
+
+# Single test
+go test ./providers/openai/ -run TestResolveModelFamily -v -count=1
+
+# All tests including integration (requires API keys)
+task test
+```
+
+### 4. Security (optional, not in CI gate)
+
+```bash
+task security
+```
+
+## CI → Local Mapping
+
+| CI Step | Local Command |
+|---------|--------------|
+| License check | `task license:check` |
+| Lint (all issues, with fix) | `task lint` |
+| Unit tests | `task test:unit` |
+| All of the above | `task ci` |
+
+## Common Failures
+
+1. **Missing license header** — Fix: `task license`
+2. **wsl_v5 whitespace** — Add blank lines before `if`/`return` after multi-line blocks
+3. **funcorder** — Move constructor `NewFoo()` above `Foo.Method()`
+4. **Test flakes on integration** — Integration tests hit live APIs; re-run or use `task test:unit`
+5. **Import grouping** — gofumpt enforced: stdlib, then external, then internal