Expand docs: trigger modes, check-trigger action, and setup guide

CLAUDE.md

@@ -8,12 +8,12 @@ git-glimpse is a GitHub Action + CLI that automatically generates visual demo cl
 
 ```
 packages/
-  core/      — Core library: diff analysis, script generation, recording, publishing
-  action/    — GitHub Action wrapper
-  cli/       — CLI for local use (`npx git-glimpse`)
-frameworks/  — Framework-specific route detectors (Remix, Next.js, SvelteKit)
-examples/    — Example project configurations
-tests/       — Integration tests
+  core/         — Core library: diff analysis, trigger logic, script generation, recording, publishing
+  action/       — GitHub Action wrapper (main action + check-trigger companion)
+  cli/          — CLI for local use (`npx git-glimpse`)
+check-trigger/  — Lightweight companion action for early trigger evaluation
+examples/       — Example project configurations
+tests/          — Integration and unit tests
 ```
 
 ## Development Setup

CONTRIBUTING.md

@@ -0,0 +1,65 @@
+# Contributing to GitGlimpse
+
+## Setup
+
+```bash
+pnpm install
+pnpm build
+pnpm test
+```
+
+Node.js ≥ 20 and pnpm are required. For integration tests you also need FFmpeg and Playwright Chromium:
+
+```bash
+sudo apt-get install -y ffmpeg                      # Linux
+brew install ffmpeg                                # macOS
+pnpm --filter @git-glimpse/core exec playwright install chromium --with-deps
+```
+
+## Repo structure
+
+```
+packages/
+  core/         — Core library: diff analysis, trigger logic, script generation, recording, publishing
+  action/       — GitHub Action wrapper (main action + check-trigger companion)
+  cli/          — CLI for local use (`npx git-glimpse`)
+check-trigger/  — Lightweight companion action for early trigger evaluation
+examples/       — Example project configurations
+tests/          — Integration and unit tests
+```
+
+## Running tests
+
+```bash
+pnpm test                   # unit tests (fast, no external deps)
+pnpm run test:integration   # Playwright + FFmpeg (no API key needed)
+pnpm run test:llm           # full pipeline with real LLM (requires ANTHROPIC_API_KEY)
+```
+
+## Making changes
+
+- **Core logic** lives in `packages/core/src/`
+- **Action entrypoint** is `packages/action/src/index.ts`
+- **Check-trigger entrypoint** is `packages/action/src/check.ts`
+- After changing action source, rebuild the dist: `pnpm build` in `packages/action`
+
+## Branching
+
+- Features: `feat/<name>`
+- Bug fixes: `fix/<name>`
+- Releases: `release/v<version>`
+
+## Submitting a PR
+
+1. Fork the repo and create a branch from `main`
+2. Make your changes with tests where applicable
+3. Run `pnpm test` and confirm everything passes
+4. Open a PR with a clear description of what changed and why
+
+## Reporting issues
+
+Please include:
+- What you expected to happen
+- What actually happened
+- Your `git-glimpse.config.ts` (redact any secrets)
+- The GitHub Actions log output if relevant