docs(devops): refresh backend audit baseline

docs/devops/CODING_AGENT_AUTOMATION_PLAYBOOK.md

@@ -137,6 +137,13 @@ cd /Users/sd9235/code/mygh/learning_ai_common_plat
 pnpm test    # runs all package + service tests
 ```
 
+**Current backend baseline (2026-03-21):**
+
+| Service              | Test Files | Tests | Status |
+| -------------------- | ---------- | ----- | ------ |
+| `platform-service`   | 117        | 1,344 | ✅     |
+| `extraction-service` | 12         | 136   | ✅     |
+
 ### 2d. Mobile Tests (Expo / native)
 
 ```bash
@@ -176,6 +183,26 @@ for repo in learning_ai_fastgap learning_ai_jarvis_jr learning_ai_trails learnin
 done
 ```
 
+Shared services can be audited the same way when the change touches common infrastructure:
+
+```bash
+for service in platform-service extraction-service; do
+  echo "=== $service ==="
+  BDIR="/Users/sd9235/code/mygh/learning_ai_common_plat/services/$service/src/modules"
+  for mod in $(ls -d $BDIR/*/ 2>/dev/null); do
+    modname=$(basename $mod)
+    if find $mod -name "*.test.ts" 2>/dev/null | grep -q .; then
+      echo "  ✅ $modname"
+    else
+      echo "  ❌ $modname (NO TEST)"
+    fi
+  done
+  echo
+done
+```
+
+**Current note (2026-03-21):** Product backends and shared common-platform backend modules all have colocated test coverage, including `platform-service/src/modules/ai-diagnostics`.
+
 **Agent action:**
 
 1. For each `❌` module, read its `types.ts`, `repository.ts`, and `routes.ts`.