Existing Backend Audit

Existing Backend Audit

Purpose

Build an accurate picture of an existing backend — framework, layering, API surface, auth model, data access, async work, integrations, tests, and risks — before any change is planned. Read-only: it changes nothing.

When to Use

• Before enhancing, refactoring, or migrating an existing backend.
• When onboarding this system onto a backend it hasn't seen.
• Not for greenfield projects (use backend-stack-selection).

Inputs

• Repository access (read-only) and any prior audit in ../../../projects/current/ or ../../../generated/.
• The request driving the audit (what change is coming).

Discovery Questions

• What framework/runtime and versions are in use? Any deprecated majors?
• How is the code layered (routes/controllers/services/data)? Is business logic in handlers?
• How are authentication and authorization enforced, and where?
• What data layer and database are used? Migrations tracked?
• What background jobs, queues, webhooks, and third-party integrations exist?
• What is tested, and does CI run it?

Responsibilities

• Inventory: framework, structure/layering, API surface (routes, versioning), validation approach, error handling, auth/authorization model, data layer + schema/migrations state, jobs/queues/schedulers, integrations/webhooks, config/secrets handling, logging/observability, tests + CI.
• Flag risks: missing authorization checks, unvalidated inputs, secrets in code, unbounded queries, missing rate limits on public endpoints, untested critical paths.
• Record findings where planning skills can consume them.

Required Workflow

1. Map entry points and layering from the code (not from stale docs).
2. Trace one representative request end-to-end (route → validation → authz → service → data).
3. Inventory the areas above; note versions and drift.
4. List risks with evidence (file:line), separated Confirmed vs Potential.
5. Record findings for the planning skill that triggered the audit.

Decision Rules

• Evidence over assumption: every claim cites a file or config.
• Depth follows the upcoming change — audit deeply where the change lands, broadly elsewhere.
• Security findings route to ../../security-review; don't duplicate its assessment here.

Rules

• Read-only. No fixes, no dependency changes, no "quick cleanups."
• Never print secrets found during the audit; flag location + rotation need only.
• Mark unverified behavior "unverified until run" rather than asserting it.

Anti-Patterns

• Fixing issues mid-audit.
• Trusting README/docs over the actual code.
• Auditing every module at equal depth regardless of the planned change.
• Vague findings ("auth looks weak") without file references.

Validation Checklist

• Framework, versions, layering mapped from code.
• One request traced end-to-end.
• API surface, auth model, data layer, async work, integrations inventoried.
• Tests + CI state recorded.
• Risks listed with evidence, Confirmed vs Potential.
• Nothing modified.

Definition of Done

A recorded backend inventory + risk list with evidence, scoped to the upcoming change, consumable by planning skills — and an untouched codebase.

Related Skills

../../existing-project-audit, backend-stack-selection, backend-api-architecture, ../../security-review, ../../dependency-audit, ../../environment-audit, ../../database/database-selection.

Related Knowledge

../../../knowledge/ (known architecture decisions, service history).

Related References

../../../references/backend/ (audit notes, when populated).

Context Loading Guidance

• Requires: repo read access, the driving request.
• Does not require: frontend/mobile code, full git history, all references.
• May load: ../../security-review (findings hand-off), ../../dependency-audit.
• Stop when: findings are recorded for the planning skill.

Token Efficiency Guidance

Sample representative files per layer instead of reading everything; trace one request deeply rather than all routes shallowly. Summarize findings — don't paste code bodies.