docs(02): create gap closure plan for DIAG-02 and Surefire fix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/ROADMAP.md

@@ -45,12 +45,13 @@ Plans:
   2. User can full-text search across message bodies, headers, error messages, and stack traces and find matching transactions
   3. User can retrieve a transaction's detail view showing the nested processor execution tree
   4. Route diagrams are stored with content-addressable versioning (identical definitions stored once), each transaction links to its active diagram version, and diagrams can be rendered from stored definitions
-**Plans:** 1/3 plans executed
+**Plans:** 4 plans (3 executed, 1 gap closure)
 
 Plans:
 - [ ] 02-01-PLAN.md -- Schema extension, core domain types, ingestion updates for search/detail columns
 - [ ] 02-02-PLAN.md -- Diagram rendering with ELK layout and JFreeSVG (SVG + JSON via content negotiation)
 - [ ] 02-03-PLAN.md -- Search endpoints (GET + POST), transaction detail with tree reconstruction, integration tests
+- [ ] 02-04-PLAN.md -- Gap closure: populate diagram_content_hash during ingestion, fix Surefire classloader isolation
 
 ### Phase 3: Agent Registry + SSE Push
 **Goal**: Server tracks connected agents through their full lifecycle and can push configuration updates, deep-trace commands, and replay commands to specific agents in real time
@@ -89,6 +90,6 @@ Note: Phases 2 and 3 both depend only on Phase 1 and could execute in parallel.
 | Phase | Plans Complete | Status | Completed |
 |-------|----------------|--------|-----------|
 | 1. Ingestion Pipeline + API Foundation | 3/3 | Complete | 2026-03-11 |
-| 2. Transaction Search + Diagrams | 1/3 | In Progress|  |
+| 2. Transaction Search + Diagrams | 3/4 | Gap Closure |  |
 | 3. Agent Registry + SSE Push | 0/2 | Not started | - |
 | 4. Security | 0/1 | Not started | - |