docs: update SESSION_STATE for CORS security fix completion (Session 20)

dev_docs/SESSION_STATE.md

@@ -1,8 +1,8 @@
 # CURRENT AI WORKING SESSION — HANDOVER
 
 **Active AI:** Claude Haiku 4.5
-**Last Updated:** 2026-04-21 (Session 19 - Network/CORS Configuration Complete)
-**Current Version:** v1.13.0 (Photo UI + Network Config - Phase 2 Complete)
+**Last Updated:** 2026-04-21 (Session 20 - CORS Security Fix Complete)
+**Current Version:** v1.13.1 (Subnet-aware CORS middleware + Phase 2 complete)
 **Branch:** dev (All changes committed, ready for Phase 3)
 
 ---
@@ -37,18 +37,27 @@
 
 ### Known Issues for Next Session
 
-**Priority 1: VPN CORS (Blocking)**
-- Problem: Subnet notation (100.78.182.0/24) creates invalid origin URLs like `https://100.78.182.0/24:8918`
-- Current workaround: `allow_origins=["*"]` (insecure, temporary)
-- Solution needed: Implement proper subnet validation in CORS middleware using `is_origin_allowed()` function
-- Files involved: `backend/main.py`, `start_server.sh`
+**RESOLVED: VPN CORS (Was Blocking) ✅**
+- ✅ Implemented `SubnetAwareCORSMiddleware` in `backend/main.py`
+- ✅ Uses `is_origin_allowed()` to validate exact origins + subnet matching
+- ✅ Handles CORS preflight (OPTIONS) properly with origin validation
+- ✅ Tested subnet parsing (100.78.182.0/24 → matches 100.78.182.x)
+- ✅ Removed insecure `allow_origins=["*"]` wildcard
+- Commit: `6f1e7731` (current session - CORS security fix)
+- Note: Old commit `904e153d` (temp CORS) is in history but no longer used
 
-**Priority 2: Clean up Temporary CORS**
-- Remove `allow_origins=["*"]` once subnet validation is working
-- Commit: `904e153d` (marked as "temp")
+**No Blocking Issues Remaining** ✅
+- Backend: 127/128 tests passing (1 unrelated schema test failure)
+- Frontend: Ready for Phase 3
 
-### Latest Commits (This Session)
+### Latest Commits (Session 19-20)
 
+**Session 20 (Current - CORS Security Fix):**
+```
+6f1e7731 fix: implement subnet-aware CORS middleware to replace insecure wildcard origins
+```
+
+**Session 19 (Network/Login Form Fixes):**
 ```
 6bf95a0d fix: prevent username input from unmounting during typing in login form
 904e153d temp: allow all CORS origins for debugging LDAP login issue