---
phase: 08-schema-foundation-and-signing-page-safety
plan: "02"
subsystem: api

tags: [nextjs, typescript, drizzle, signing, security]

# Dependency graph
requires:
  - phase: 08-schema-foundation-and-signing-page-safety
    plan: "01"
    provides: "SignatureFieldType discriminant, getFieldType(), isClientVisibleField() exported from schema.ts"
provides:
  - "Server-side agent-signature field filter in GET /api/sign/[token] response"
  - "Type-guarded handleFieldClick in SigningPageClient — non-client-signature fields skip modal open"
  - "handleSubmit completeness check counts only client-signature fields"
  - "SigningProgressBar total reflects client-signature field count only"
affects:
  - "Phase 10 (initials field type) — handleFieldClick type-switch pattern ready for extension"
  - "Phase 11 (agent signing) — server filter ensures agent-signature fields never reach client JSON"

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Defense-in-depth: server-side filter is primary protection; client-side type guard is secondary"
    - "Type-switch pattern in handleFieldClick — getFieldType() !== 'client-signature' returns early; extensible for Phase 10 initials"
    - "isClientVisibleField() as reusable predicate for .filter() on signatureFields arrays"

key-files:
  created: []
  modified:
    - "teressa-copeland-homes/src/app/api/sign/[token]/route.ts"
    - "teressa-copeland-homes/src/app/sign/[token]/_components/SigningPageClient.tsx"

key-decisions:
  - "Server-side filter is the primary security boundary — client guards are defense-in-depth only; direct API callers (curl, DevTools) cannot see agent-signature coordinates"
  - "POST handler in route.ts is intentionally untouched — signature embedding pipeline reads signatureFields from DB directly, not from client payload"
  - "handleFieldClick dependency array includes signatureFields — required because callback now calls signatureFields.find()"
  - "Phase 8 ships atomically: 08-01 schema + 08-02 boundary enforcement together; no intermediate state where type discriminant exists but filter is absent"

patterns-established:
  - "Type-switch guard pattern: const field = signatureFields.find(f => f.id === fieldId); if (getFieldType(field) !== 'client-signature') return; — establishes extensible branch for Phase 10"
  - "Filter before JSON serialization: (doc.signatureFields ?? []).filter(isClientVisibleField) — server owns the boundary"

requirements-completed: [FIELD-01]

# Metrics
duration: ~10min (continuation from checkpoint)
completed: 2026-03-21
---

# Phase 8 Plan 02: Signing Page Safety Summary

**Server-side agent-signature filter in GET /api/sign/[token] and type-branching guards in SigningPageClient.tsx — Phase 8 safety gate ships atomically with 08-01 schema foundation**

## Performance

- **Duration:** ~10 min (continuation agent from human-verify checkpoint)
- **Started:** 2026-03-21 (resumed from checkpoint)
- **Completed:** 2026-03-21T17:54:22Z
- **Tasks:** 3 (Tasks 1 and 2 completed in prior session; Task 3 checkpoint approved and recorded)
- **Files modified:** 2

## Accomplishments

- Added `isClientVisibleField` import and `.filter(isClientVisibleField)` to the GET /api/sign/[token] response, ensuring agent-signature field coordinates are never serialized to the client JSON response
- Added `getFieldType` import and type-branching guard to `handleFieldClick` in SigningPageClient — clicking a non-client-signature field overlay now returns early instead of opening the signature modal
- Fixed `handleSubmit` completeness check and `SigningProgressBar` total to count only client-signature fields, so agent-signature fields (never rendered) do not block submission or inflate the progress indicator
- Human verification checkpoint approved: TypeScript compiles clean, all guards confirmed, backward compatibility with v1.0 signing sessions verified

## Task Commits

Each task was committed atomically:

1. **Task 1: Add isClientVisibleField filter to GET /api/sign/[token] route** - `ea3365f` (feat)
2. **Task 2: Add type-branching guards to SigningPageClient.tsx** - `06e477b` (feat)
3. **Task 3: Human verification of Phase 8 safety gate** - `0db26db` (docs — checkpoint approval)

**Plan metadata:** (committed with this SUMMARY)

## Files Created/Modified

- `teressa-copeland-homes/src/app/api/sign/[token]/route.ts` - Added `isClientVisibleField` import; GET response now filters signatureFields to exclude agent-signature fields before JSON serialization
- `teressa-copeland-homes/src/app/sign/[token]/_components/SigningPageClient.tsx` - Added `getFieldType` import; handleFieldClick type guard; handleSubmit client-signature-only count; SigningProgressBar client-signature-only total

## Decisions Made

- Server-side filter in route.ts is the primary security boundary. Client-side guard in SigningPageClient is defense-in-depth. A caller hitting GET /api/sign/[token] directly (curl, browser DevTools) sees only client-visible fields regardless of the client component.
- POST handler in route.ts intentionally untouched. The signature embedding pipeline reads `signatureFields` from the DB directly — not from any client payload — so no filter is needed or appropriate there.
- `signatureFields` added to `handleFieldClick` dependency array because the callback now calls `signatureFields.find()`. This is correct React hook semantics.
- Phase 8 ships as a single atomic unit: 08-01 exports the type helpers; 08-02 uses them at both enforcement boundaries. There is no valid intermediate state.

## Deviations from Plan

None — plan executed exactly as written. Both auto-task changes matched the specified diffs precisely. Human verification checkpoint approved without issues.

## Issues Encountered

None.

## User Setup Required

None — no external service configuration required.

## Next Phase Readiness

- Phase 8 is fully complete: schema foundation (08-01) and signing page safety (08-02) are both active
- Phase 9 (agent signature capture) can now proceed — the `agent-signature` field type is defined in schema.ts and the server filter will automatically exclude agent-signature fields from all client signing sessions
- Phase 10 (initials field type) is unblocked — the `handleFieldClick` type-switch pattern is established and ready for an `else if (getFieldType(field) === 'initials')` branch

---
*Phase: 08-schema-foundation-and-signing-page-safety*
*Completed: 2026-03-21*
