docs(04-02): complete query interface plan

Tasks completed: 3/3
- Add graph query helpers
- Create graph-backed summary generator
- Integrate graph summary into regeneration flow

SUMMARY: .planning/phases/04-semantic-intelligence/04-02-SUMMARY.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/phases/04-semantic-intelligence/04-02-SUMMARY.md

@@ -0,0 +1,99 @@
+---
+phase: 04-semantic-intelligence
+plan: 02
+subsystem: intel
+tags: [sqlite, sql-js, graph-query, recursive-cte, summary-generation]
+
+requires:
+  - phase: 04-01
+    provides: SQLite graph layer with nodes/edges schema
+provides:
+  - Graph query helpers (getHotspots, getNodesByType, getDependents)
+  - Graph-backed summary generation (generateGraphSummary)
+  - Transitive dependent queries via recursive CTE
+affects: [04-03, context-injection, session-start]
+
+tech-stack:
+  added: []
+  patterns:
+    - Recursive CTE for transitive graph traversal
+    - Graph-backed summary with hotspot analysis
+
+key-files:
+  created: []
+  modified:
+    - hooks/gsd-intel-index.js
+
+key-decisions:
+  - "LEFT JOIN allows edges to exist before target nodes indexed"
+  - "UNION (not UNION ALL) prevents infinite loops in cyclic graphs"
+  - "maxDepth limit on recursive CTE prevents runaway queries"
+
+patterns-established:
+  - "Graph queries return structured arrays with id/path/type"
+  - "Summary prefers graph when available, falls back to entity-file-based"
+
+duration: 2min
+completed: 2026-01-20
+---
+
+# Phase 4 Plan 2: Query Interface Summary
+
+**Graph-backed summary generation with dependency hotspots, type grouping, and recursive CTE for transitive dependents**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-01-20T15:56:42Z
+- **Completed:** 2026-01-20T15:59:07Z
+- **Tasks:** 3
+- **Files modified:** 1
+
+## Accomplishments
+
+- Added graph query helpers (getHotspots, getNodesByType, getDependents)
+- Created generateGraphSummary() that queries SQLite for rich semantic summaries
+- Integrated graph summary into regeneration flow with entity-file fallback
+- Verified SessionStart hook correctly injects graph-backed summary into context
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add graph query helpers** - `5824196` (feat)
+2. **Task 2: Create graph-backed summary generator** - `3d8cf70` (feat)
+3. **Task 3: Integrate graph summary into regeneration flow** - `101bc58` (feat)
+
+## Files Created/Modified
+
+- `hooks/gsd-intel-index.js` - Added graph query helpers and summary generator
+
+## Decisions Made
+
+- **LEFT JOIN on nodes**: Allows edges to exist even if target node not yet indexed (forward references)
+- **UNION vs UNION ALL**: Using UNION in recursive CTE prevents infinite loops in cyclic dependency graphs
+- **maxDepth default of 5**: Prevents runaway queries on deeply nested dependencies
+- **All entity IDs lowercased**: Ensures consistent matching across queries
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+
+- Graph query interface complete
+- Summary generation produces < 500 token output (47 words in test)
+- SessionStart hook verified working with new graph-backed format
+- Ready for 04-03: Entity generation instructions integration
+
+---
+*Phase: 04-semantic-intelligence*
+*Completed: 2026-01-20*