**ClickHouse schema extended with 12 search/detail columns, SearchEngine abstraction for swappable backends, and ingestion populating tree metadata + exchange data**
## Performance
- **Duration:** 13 min
- **Started:** 2026-03-11T15:03:14Z
- **Completed:** 2026-03-11T15:15:47Z
- **Tasks:** 2
- **Files modified:** 15
## Accomplishments
- Extended ClickHouse route_executions table with 12 new columns for exchange data, processor tree metadata, and diagram linking
- Used FlatProcessor record to carry depth and parentIndex alongside the ProcessorExecution during DFS flattening -- single pass, no separate traversal
- Exchange bodies and headers concatenated into single String columns (not Array(String)) for efficient LIKE '%term%' search
- Headers serialized to JSON strings using a static Jackson ObjectMapper (no Spring injection needed)
- diagram_content_hash left empty during ingestion (wired at query time or by Plan 03 -- DIAG-02 can be satisfied by joining route_diagrams)
- Created DiagramRenderer/DiagramLayout stubs in core module to fix pre-existing compilation error from Phase 1 Plan 02
## Deviations from Plan
### Auto-fixed Issues
**1. [Rule 3 - Blocking] Created DiagramRenderer and DiagramLayout stub interfaces**
- **Found during:** Task 2 (compilation step)
- **Issue:** Pre-existing `ElkDiagramRenderer` in app module referenced `DiagramRenderer` and `DiagramLayout` interfaces that did not exist in core module, causing compilation failure
**2. [Rule 1 - Bug] Fixed ClickHouse Array type handling in IngestionSchemaIT**
- **Found during:** Task 2 TDD RED phase
- **Issue:** ClickHouse JDBC returns `com.clickhouse.jdbc.types.Array` from `queryForList`, not `java.util.List` -- test casts failed with ClassCastException
- **Fix:** Created `queryArray()` helper method using `rs.getArray(1).getArray()` with proper type dispatch for Object[], short[], int[]
**Impact on plan:** Both auto-fixes necessary for compilation and test correctness. No scope creep.
## Issues Encountered
- Pre-existing ElkDiagramRendererTest breaks Spring context when run in full test suite (ELK static initialization + xtext classloading issue). Documented in deferred-items.md. All tests pass when run individually or grouped without ElkDiagramRendererTest.
## User Setup Required
None - no external service configuration required.
## Next Phase Readiness
- Schema foundation and domain types ready for Plan 02 (search endpoints with ClickHouseSearchEngine) and Plan 03 (detail/diagram endpoints)
- SearchEngine interface ready for ClickHouseSearchEngine implementation
- ExecutionRepository.findRawById ready for ClickHouse implementation
- AbstractClickHouseIT loads both schema files for all subsequent integration tests
## Self-Check: PASSED
All 8 key files verified present. All 3 task commits verified in git log.
