# Methodology — how this was verified

Repeatable procedure (executed Oct 11–12, 2026). Tools: `curl`, `node` (packages `ws`, `mqtt`), `jq`.

## Steps

1. **Map the target:** fetch the site's HTML + JS bundles with curl; read the CSP header (`connect-src` names allowed WebSocket endpoints); grep bundles for protocol strings → found oyenza's own WS (`/api/live`) and its message types (`hello/feed/snap/delta`).
2. **Find static-data citations:** `static.json` referenced the official GTFS zip URL → static layer source identified.
3. **Find the upstream:** search GitHub for projects in the same ecosystem (`tj-live`, `open-tj`) → they document the REST + MQTT + GTFS stack.
4. **Simultaneous cross-capture:**
   - `oyenza-ws.mjs` — WS client on `wss://transit.oyenza.com/api/live`
   - `mqtt-cap.mjs` / `mqtt-long.mjs` — MQTT client on `wss://mqtt.tj.co.id:8084/mqtt`, subscribing `/mobile_armada/#`
   - Analysis with `compare.mjs` / `compare2.mjs` (ID sets, field agreement, position deltas), `seg1.mjs` (topic segments), `mqtt-rate.mjs` (rate profile).
5. **Decode the topic grid:** four `POST /v1/bus` probes at ±0.1° offsets → index-shift mapping (≈0.01°/unit).
6. **Cadence check:** re-connect to oyenza's WS and record delta intervals (`oy2.mjs`) → exactly ~3.00 s.

## Key results

- 1,794 common buses; 100% trip/route ID match; median position delta 8.9 m; p90 42 m; 97.8% fleet overlap (75 s window).
- Broker: ~2,000+ retained messages instantly on subscribe; per-bus refresh ~8–75 s in samples.
- oyenza deltas: 3000–3013 ms gaps, ~1,000 position records each.

## Artifacts

- All scripts + raw captures archived at `workspace/transjakarta-live-captures/` (4.6 MB): oyenza page + bundles, oyenza WS captures, MQTT captures, comparison outputs, rate profiles, tije REST responses (guest token redacted).
- Scratch copies live under `~/.hermes/profiles/research/cache/scratch/oyenza/` (auto-pruned after ~24 h idle — use the archive instead).
- Reusable snapshot tool: [[transjakarta-live-data/scripts/tj-snapshot.mjs|scripts/tj-snapshot.mjs]]