audit: 2026-05-30 full-codebase audit — report, issues, docs, runbooks

Full-codebase-audit 2026-05-30 outputs:
- Audit report: 09 - Audits/Full Codebase Audit - 2026-05-30.md
- 81 issue files ISSUE-055..135 (decisions + 1 skipped no-brainer).
- Scanner docs from scratch (was zero): architecture, data model, API ref, payment
  flow, operations runbook + repo README.
- Doc-sync updates across API reference, data models, flows, design system.
- Secret Rotation Runbook (08 - Operations) for the exposed credentials.
- Reusable workflow guide (07 - Development) + .claude/workflows/full-codebase-audit.js.

Issues remain status:open intentionally — the code fixes are uncommitted-then-committed
working-tree changes per repo and aren't "resolved" until merged/deployed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Issues/ISSUE-070-backend-notifyallsellersaboutnewrequest-unbounded-fan-out.md

@@ -0,0 +1,38 @@
+---
+issue: 070
+title: "Backend: notifyAllSellersAboutNewRequest unbounded fan-out — N DB writes + N socket emits per new request"
+severity: high
+domain: Marketplace
+labels: [performance, backend, scalability]
+status: open
+created: 2026-05-30
+source: Full Codebase Audit 2026-05-30
+---
+
+# Backend: notifyAllSellersAboutNewRequest unbounded fan-out — N DB writes + N socket emits per new request
+
+**Severity:** high
+**Domain:** Marketplace
+**Labels:** performance, backend, scalability
+
+## Description
+
+`PurchaseRequestService.ts:196` loops over every seller and issues one `Notification.insertOne` and one `socket.emit` per seller, wrapped in `setTimeout`. With hundreds of sellers this creates hundreds of sequential DB writes and socket emits, blocking the event loop and risking OOM.
+
+## Options
+
+1. Batch with `insertMany` for notifications and a single room/broadcast emit instead of per-seller `setTimeout`.
+2. Move to a queue/worker that processes seller notifications asynchronously with concurrency limits.
+3. Fan out via a topic/room subscription rather than per-seller writes.
+
+## Recommendation
+
+Use `insertMany` + a single broadcast/room emit, or offload to a queue with bounded concurrency. This is an architectural change.
+
+## Affected Files
+
+- `backend/src/services/marketplace/PurchaseRequestService.ts:196`
+
+## References
+
+- [Full Codebase Audit 2026-05-30](../09%20-%20Audits/Full%20Codebase%20Audit%20-%202026-05-30.md) — DEC-40