Based on the repository's commit message style and the changes in the diff, here's an appropriate commit message:

```
feat: add websocket tests, PoA metrics, marketplace endpoints, and enhanced observability

- Add comprehensive websocket tests for blocks and transactions streams including multi-subscriber and high-volume scenarios
- Extend PoA consensus with per-proposer block metrics and rotation tracking
- Add latest block interval gauge and RPC error spike alerting
- Enhance mock coordinator

apps/coordinator-api/README.md

@@ -4,6 +4,27 @@
 
 FastAPI service that accepts client compute jobs, matches miners, and tracks job lifecycle for the AITBC network.
 
+## Marketplace Extensions
+
+Stage 2 introduces public marketplace endpoints exposed under `/v1/marketplace`:
+
+- `GET /v1/marketplace/offers` – list available provider offers (filterable by status).
+- `GET /v1/marketplace/stats` – aggregated supply/demand metrics surfaced in the marketplace web dashboard.
+- `POST /v1/marketplace/bids` – accept bid submissions for matching (mock-friendly; returns `202 Accepted`).
+
+These endpoints serve the `apps/marketplace-web/` dashboard via `VITE_MARKETPLACE_DATA_MODE=live`.
+
+## Explorer Endpoints
+
+The coordinator now exposes read-only explorer data under `/v1/explorer` for `apps/explorer-web/` live mode:
+
+- `GET /v1/explorer/blocks` – block summaries derived from recent job activity.
+- `GET /v1/explorer/transactions` – transaction-like records for coordinator jobs.
+- `GET /v1/explorer/addresses` – aggregated address activity and balances.
+- `GET /v1/explorer/receipts` – latest job receipts (filterable by `job_id`).
+
+Set `VITE_DATA_MODE=live` and `VITE_COORDINATOR_API` in the explorer web app to consume these APIs.
+
 ## Development Setup
 
 1. Create a virtual environment in `apps/coordinator-api/.venv`.