---
date: '2026-02-14T17:00:00Z'
author: claude-opus-4-6
session: harden-api-validation-178
type: handoff
importance: 0.8
tags: [handoff, security, validation, ws6, ws10]
supersedes: null
signature: pending
---

# Handoff: API Validation Hardening (#178)

## What Was Done This Session

- Designed and implemented full input validation hardening per issue #178
- Added prompt injection scanning via `@andersmyrmel/vard` library
  - `scanForInjection()` flags suspicious content without blocking writes
  - AI consumers (MCP tools) can filter or warn based on `injectionRisk` field
  - 31 unit tests with performance benchmarks (<50ms p95)
- Added DB migration for `injection_risk` boolean column on `diary_entries`
- Added `maxLength(88)` on all Ed25519 signature fields (64 bytes base64)
- Added `maxLength(500)` on challenge fields in recovery route
- Added pattern validation on `visibility` and `status` query params
- Added fingerprint pattern validation on `sharedWith` field
- Added voucher code hex pattern `^[a-f0-9]{64}$` on registration
- Made `FingerprintSchema` case-insensitive, normalize to uppercase on lookup/verify
- Added trust graph pagination (limit/offset) with `Cache-Control` header
- Validated problems route `:type` param against registered slug enum
- Enabled `removeAdditional: true` in Fastify Ajv config (rest-api + combined server)
- Updated all test fixtures for `injectionRisk` field across 4 test files

## What's Not Done Yet

- PR not yet created (branch pushed, ready for PR creation)
- Manual smoke testing against local Docker
- Migration has not been applied to any environment
- Mission integrity checks should be included in PR body

## Current State

- Branch: `claude/harden-api-validation-178`
- Tests: 314 passing across all packages, 0 failing
- Lint: 0 errors
- Typecheck: all packages pass (pre-existing tools TS6305 unrelated)
- 4 commits on branch (database, diary-service, models, rest-api)

## Decisions Made

- **Flag, don't block**: injection scanner sets `injectionRisk: true` but does not reject the entry — preserves agent autonomy while surfacing risk to consumers
- **vard over custom regex**: chose `@andersmyrmel/vard` for maintained prompt injection detection rather than hand-rolled patterns
- **removeAdditional: true**: Fastify's Ajv now strips undeclared properties from request bodies, defense-in-depth against unexpected fields
- **400 not 404 for unknown problem types**: changing `:type` param to `Type.Union` of registered slugs means Fastify schema validation rejects unknown values before the handler runs
- **Case-insensitive fingerprints**: accept `[A-Fa-f0-9]` in schema, normalize to uppercase in handlers — agents shouldn't fail over case mismatch

## Open Questions

- Should MCP tools surface `injectionRisk` to agents directly, or filter flagged entries silently?
- Should we add rate limiting specifically for entries flagged as injection risks?

## Where to Start Next

1. Create PR with mission integrity checks in body
2. Apply migration locally: `pnpm docker:reset && docker compose up -d`
3. Smoke test injection detection end-to-end
4. Consider MCP tool changes to surface `injectionRisk` to agent consumers
