# Per-Node Rate Limit Policy (2026-10-04)

## Why

All 4 fleet nodes (muse, pip, 646, opm) egress from a single Cloudflare IP
(`104.28.195.181`). Cloudflare therefore sees the whole fleet as one client.
When fleet timers fire simultaneously, synchronized send bursts look like one
aggressive client and invite correlated rate-limiting — the likely shape of
the "all 4 browsers flapping" episodes.

Per-agent rate limiting with deterministic jitter de-correlates the fleet:
each node's send phase drifts apart instead of hitting in lockstep.

## Policy

| Agent | Base interval | Jitter factor | Effective interval | Burst | Max/min |
|---|---|---|---|---|---|
| muse | 3.0s | 1.2917 | 3.875s | 5 | 20 |
| pip  | 3.0s | 0.8183 | 2.455s | 5 | 20 |
| 646  | 3.0s | 1.1193 | 3.358s | 5 | 20 |
| opm  | 3.0s | 0.8287 | 2.486s | 5 | 20 |

Mean effective interval ≈ 3.04s — the jitter does **not** make limits
stricter on average; it only spreads phases.

- **Jitter:** ±30% deterministic per agent, seeded by
  `sha256("netvm-rate-jitter:v1:" + agent)`. Same agent → same factor every
  run (reproducible); different agents → different factors (de-correlated).
  Uses an isolated `random.Random`, never touches global random state.
- **Scope:** per-agent token buckets. State lives in one shared file
  (`/tmp/netvm-rate-limit.json`) but keys are namespaced by agent
  (`{agent}`, `{agent}_recent`) — buckets are fully independent.
- **Enforcement points:**
  - `job-dispatch.py` — `rate_limit_wait(agent)` / `rate_limit_wait(sender_agent)`
    (pre-existing; now jittered, no call-site change needed)
  - `dm.py::dm_send` — `rate_limit_wait(agent)` before send, keyed on the
    sender (added 2026-10-04). Near no-op at normal pacing since sends
    already sleep 2–3s; it only bites on burst loops.

## Inspect

```bash
python3 bin/rate_limiter.py --policy            # effective policy per agent
python3 bin/rate_limiter.py --policy opm --no-jitter
```

## Notes

- `/tmp` state does not survive reboots; buckets start empty (permissive).
- To disable jitter for a caller: `rate_limit_wait(agent, jitter=0)`.
- Distinct egress IPs per node (Cloudflare Zero Trust dedicated egress)
  remains the structural fix; this policy is the de-correlation layer that
  works regardless.