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>

02 - Data Models/ConfigSettingHistory.md

@@ -0,0 +1,49 @@
+---
+title: ConfigSettingHistory
+tags: [data-model, mongoose, admin, audit]
+aliases: [Setting History, Threshold History, IConfigSettingHistory]
+created: 2026-05-30
+---
+
+# ConfigSettingHistory
+
+> **Added:** 2026-05-30 — introduced in commit `27fb15a` as part of Task #9 (per-chain confirmation thresholds + audit log).
+
+Audit trail document that records every change to a runtime configuration setting. Currently used exclusively to log confirmation-threshold updates (`key` pattern: `confirmation_threshold:<chainId>`), but the schema is generic and can store other numeric runtime config changes.
+
+> [!note] Source
+> `backend/src/models/ConfigSettingHistory.ts` — schema and model export.
+> Written by `backend/src/services/payment/safety/confirmationThresholdService.ts` (`setConfirmationThreshold`).
+> Read by `GET /api/admin/settings/confirmation-thresholds/history` in `confirmationThresholdRoutes.ts`.
+
+## Schema
+
+| Field | Type | Required | Default | Description |
+| --- | --- | --- | --- | --- |
+| `key` | String | yes | — | Setting identifier. Format: `confirmation_threshold:<chainId>` for threshold changes. Indexed. |
+| `oldValue` | Number | no | `null` | Value before the change. `null` when the setting had no prior database entry. |
+| `newValue` | Number | yes | — | Value after the change. |
+| `changedBy` | ObjectId (ref: `User`) | no | — | Admin user who made the change. Populated by `GET …/history` via `.populate('changedBy', 'email name')`. |
+| `changedAt` | Date | no | `Date.now()` | Timestamp of the change. Indexed; used for sort-descending pagination. |
+
+> [!note] No `timestamps: false`
+> The schema deliberately disables Mongoose's automatic `createdAt`/`updatedAt` fields (`timestamps: false`) because `changedAt` is the canonical timestamp.
+
+## Example document
+
+```json
+{
+  "_id": "6657c3...",
+  "key": "confirmation_threshold:56",
+  "oldValue": 12,
+  "newValue": 6,
+  "changedBy": { "_id": "...", "email": "admin@amn.gg" },
+  "changedAt": "2026-05-30T10:22:00.000Z"
+}
+```
+
+## Related
+
+- [[Payment API]] — `GET /api/admin/settings/confirmation-thresholds/history`
+- [[Admin API]] — confirmation thresholds section
+- `backend/src/services/payment/safety/confirmationThresholdService.ts`