User report 2026-05-04: 8+ workspace tenant (Design Director + 6 sub-agents
+ 3 standalones) saw sustained 429s in canvas console hitting
/workspaces/<id>/activity?limit=5. Server-side rate limit is 600 req/min/IP.
Three compounding issues in CommunicationOverlay:
1. Polled regardless of visibility — collapsed panel still hammered the API
2. 10s cadence — 6 req every 10s = 36 req/min from this overlay alone
3. Fan-out cap of 6 workspaces — scaled linearly with workspace count
Fix:
- Gate setInterval on `visible` (effect re-runs when collapsed/expanded)
- Cadence 10s → 30s
- Fan-out cap 6 → 3
Combined: ~36 req/min worst case → 6 req/min worst case (6x reduction),
0 req/min when collapsed.
Tests:
- Fan-out cap: 6 online nodes mounted → exactly 3 fetches (was 6)
- Offline gate: offline workspace never polled
- Cadence: timer at 10s = no new fetch; timer at 30s = next batch fires
Each test would fail if the corresponding dial regressed.
Follow-up (out of scope): structurally right fix is to consume the
WORKSPACE_ACTIVITY WS broadcast instead of polling per-workspace. Server
already publishes the events; canvas just isn't subscribing yet.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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