docs: define milestone v1.2 requirements

.planning/REQUIREMENTS.md

@@ -100,6 +100,30 @@
 - [x] **TXTF-02**: When a text field is selected, PreparePanel shows quick-fill suggestion buttons (Client Name, Property Address, Client Email) that insert the corresponding value into the selected field
 - [x] **TXTF-03**: Text fill values entered per-field appear correctly embedded in the preview PDF and the final prepared PDF; the staleness token resets on any text field value change
 
+## v1.2 Requirements
+
+### Multi-Signer
+
+- [ ] **MSIGN-01**: Agent can add named signers to a document by email address from PreparePanel before sending
+- [ ] **MSIGN-02**: Agent can tag each signature, initials, and date field to a specific signer when placing in FieldPlacer
+- [ ] **MSIGN-03**: Fields in FieldPlacer are color-coded by assigned signer for visual distinction
+- [ ] **MSIGN-04**: Agent cannot send a document if any client-facing field (signature, initials, date, text) has no signer assigned — send is blocked with a clear error
+- [ ] **MSIGN-05**: Document recipients list is built automatically from unique signer emails on placed fields (no separate manual entry)
+- [ ] **MSIGN-06**: All signers receive their unique signing links simultaneously when agent sends
+- [ ] **MSIGN-07**: Each signer's signing page shows only their own assigned fields — other signers' fields are not visible
+- [ ] **MSIGN-08**: Server enforces field ownership — a signer can only submit fields assigned to them
+- [ ] **MSIGN-09**: Dashboard shows per-signer completion status (who has signed, who hasn't)
+- [ ] **MSIGN-10**: When all signers complete, agent receives a notification email
+- [ ] **MSIGN-11**: When all signers complete, all parties (each signer + agent) receive the final merged PDF via email link
+
+### Deployment
+
+- [ ] **DEPLOY-01**: Application runs in Docker with a production docker-compose.yml (node:20-slim, three-stage build, not Alpine)
+- [ ] **DEPLOY-02**: All secrets (SMTP, database URL, API keys) are injected at container runtime via env_file — not baked into image
+- [ ] **DEPLOY-03**: Email delivery works correctly from the Docker container (SMTP connects to external SMTP server from container)
+- [ ] **DEPLOY-04**: GET /api/health returns 200 OK when the database is reachable
+- [ ] **DEPLOY-05**: Uploaded PDF files persist across container restarts (named Docker volume for uploads directory)
+
 ## v2 Requirements
 
 ### MLS Integration
@@ -204,9 +228,10 @@ Which phases cover which requirements. Updated during roadmap creation.
 **Coverage:**
 - v1.0 requirements: 28 total — mapped to phases 1-7 — all Complete
 - v1.1 requirements: 17 total — mapped to phases 8-13 — 13 Complete, 4 Pending (INIT-01 through INIT-04)
-- Total mapped: 45
+- v1.2 requirements: 16 total — mapped to phases 14+ — all Pending
-- Unmapped: 0
+- Total mapped: 61
+- Unmapped: 16 (v1.2 — roadmap pending)
 
 ---
 *Requirements defined: 2026-03-19*
-*Last updated: 2026-03-21 after Phase 11.1 insertion — INIT-01 through INIT-04 added*
+*Last updated: 2026-04-03 — v1.2 requirements added (MSIGN-01–11, DEPLOY-01–05)*