pipeline-guard

# Pipeline Guard Automatically validates DOT graphs and assigns optimal models before `run_pipeline` executes. This is a lifecycle hook — it runs transparently before every pipeline execution. ## What it does 1. **Validates DOT structure** — checks for cycles, disconnected nodes, malformed syntax 2. **Assigns models from QoS catalog** — reads `model_catalog.json` scores and assigns: - Search workers (dynamic_parallel) → FAST models (round-robin across pool) - Analyze/synthesize nodes → STRONG models (best QoS score) - Planner model → STRONG 3. **Concurrent distribution** — PID-based random start index so parallel pipelines use different models ## No user action needed The LLM writes DOT graphs without `model=` attributes. This hook injects them automatically based on live QoS scores.