cameleer-server/.planning/phases/02-transaction-search-diagrams/02-02-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
02-transaction-search-diagrams	02	api	elk jfreesvg svg diagram layout content-negotiation	phase provides 01-ingestion-pipeline DiagramRepository with findByContentHash for loading RouteGraph definitions	DiagramRenderer interface in core module for SVG and JSON layout output ElkDiagramRenderer implementation using ELK layered algorithm and JFreeSVG DiagramRenderController with Accept header content negotiation Color-coded node rendering matching route-diagram-example.html style Compound node support for nested processors (CHOICE, SPLIT, TRY_CATCH)	02-03 ui-rendering execution-overlay	added patterns org.eclipse.elk.core:0.11.0 org.eclipse.elk.alg.layered:0.11.0 org.jfree.svg:5.0.7 org.eclipse.xtext.xbase.lib:2.37.0 ELK graph construction JFreeSVG rendering manual Accept header content negotiation	created modified cameleer-server-core/src/main/java/com/cameleer/server/core/diagram/DiagramRenderer.java cameleer-server-core/src/main/java/com/cameleer/server/core/diagram/DiagramLayout.java cameleer-server-core/src/main/java/com/cameleer/server/core/diagram/PositionedNode.java cameleer-server-core/src/main/java/com/cameleer/server/core/diagram/PositionedEdge.java cameleer-server-app/src/main/java/com/cameleer/server/app/diagram/ElkDiagramRenderer.java cameleer-server-app/src/main/java/com/cameleer/server/app/controller/DiagramRenderController.java cameleer-server-app/src/main/java/com/cameleer/server/app/config/DiagramBeanConfig.java cameleer-server-app/src/test/java/com/cameleer/server/app/diagram/ElkDiagramRendererTest.java cameleer-server-app/src/test/java/com/cameleer/server/app/controller/DiagramRenderControllerIT.java cameleer-server-app/pom.xml	Used ELK layered algorithm with top-to-bottom direction for route diagram layout JFreeSVG for server-side SVG generation (lightweight, no Batik dependency) Manual Accept header parsing for content negotiation -- JSON only when first preference, SVG as default Added xtext xbase lib runtime dependency required by ELK 0.11.0 LayeredMetaDataProvider Compound nodes detected via RouteNode.children rather than edge topology analysis	DiagramRenderer interface in core, implementation in app -- swappable rendering backend Accept header content negotiation: check first media type preference, default to SVG NodeType color mapping via EnumSet groupings for efficient lookup	DIAG-03	14min	2026-03-11

Phase 2 Plan 2: Diagram Rendering Summary

ELK-based route diagram rendering with color-coded SVG output, JSON layout API, and compound node swimlanes via content-negotiated REST endpoint

Performance

• Duration: 14 min
• Started: 2026-03-11T15:03:12Z
• Completed: 2026-03-11T15:17:22Z
• Tasks: 2
• Files modified: 10

Accomplishments

• Route diagrams render as color-coded top-to-bottom SVG with ELK layered algorithm
• JSON layout API returns positioned nodes and edges for client-side rendering
• Compound nodes (CHOICE, SPLIT, TRY_CATCH) render in swimlane containers with children
• Content negotiation: Accept: application/json returns JSON, everything else defaults to SVG
• 11 unit tests and 4 integration tests verify layout, colors, content types, and 404 handling

Task Commits

Each task was committed atomically:

1. Task 1: Add ELK/JFreeSVG dependencies and create core diagram rendering interfaces - 6df7450 (feat)
2. Task 2: Implement ElkDiagramRenderer, DiagramRenderController, and integration tests - c1bc32d (feat, TDD)

Files Created/Modified

• cameleer-server-core/.../diagram/DiagramRenderer.java - Renderer interface with renderSvg and layoutJson
• cameleer-server-core/.../diagram/DiagramLayout.java - Layout record (width, height, nodes, edges)
• cameleer-server-core/.../diagram/PositionedNode.java - Node record with position, dimensions, children
• cameleer-server-core/.../diagram/PositionedEdge.java - Edge record with waypoints
• cameleer-server-app/.../diagram/ElkDiagramRenderer.java - ELK + JFreeSVG implementation (~400 lines)
• cameleer-server-app/.../controller/DiagramRenderController.java - GET /api/v1/diagrams/{hash}/render
• cameleer-server-app/.../config/DiagramBeanConfig.java - Spring bean wiring for DiagramRenderer
• cameleer-server-app/pom.xml - Added ELK, JFreeSVG, xtext dependencies
• cameleer-server-app/.../diagram/ElkDiagramRendererTest.java - 11 unit tests
• cameleer-server-app/.../controller/DiagramRenderControllerIT.java - 4 integration tests

Decisions Made

• Used ELK layered algorithm (org.eclipse.elk.alg.layered) -- well-maintained, supports compound nodes natively
• JFreeSVG over Batik -- lightweight, no transitive dependency bloat, sufficient for server-side SVG generation
• Manual Accept header parsing instead of Spring content negotiation -- simpler, avoids Spring's default JSON preference when Accept includes wildcards
• Added xtext xbase lib as runtime dependency -- ELK 0.11.0's LayeredMetaDataProvider references CollectionLiterals at class init time
• Compound node children detected from RouteNode.getChildren() rather than edge topology -- cleaner and matches the agent's graph model

Deviations from Plan

Auto-fixed Issues

1. [Rule 3 - Blocking] Added xtext xbase lib dependency for ELK compatibility

• Found during: Task 2 (ElkDiagramRenderer implementation)
• Issue: ELK 0.11.0 LayeredMetaDataProvider references org.eclipse.xtext.xbase.lib.CollectionLiterals at class initialization, causing NoClassDefFoundError
• Fix: Added org.eclipse.xtext:org.eclipse.xtext.xbase.lib:2.37.0 dependency to app pom.xml
• Files modified: cameleer-server-app/pom.xml
• Verification: All unit tests pass after adding dependency
• Committed in: c1bc32d (Task 2 commit)

2. [Rule 1 - Bug] Fixed content negotiation default format

• Found during: Task 2 (integration test for default Accept header)
• Issue: TestRestTemplate sends Accept: text/plain, application/json, / by default; simple contains("application/json") check returned JSON instead of SVG
• Fix: Changed to check only the first media type in Accept header -- JSON only when explicitly first preference
• Files modified: DiagramRenderController.java
• Verification: Integration test getWithNoAcceptHeader_defaultsToSvg passes
• Committed in: c1bc32d (Task 2 commit)

3. [Rule 1 - Bug] Adapted to actual NodeType enum naming (EIP_ prefix)

• Found during: Task 2 (ElkDiagramRenderer implementation)
• Issue: Plan referenced CHOICE, SPLIT etc. but actual enum values are EIP_CHOICE, EIP_SPLIT etc.
• Fix: Used correct enum names from decompiled cameleer-common jar in all color mapping sets
• Files modified: ElkDiagramRenderer.java
• Verification: Unit tests verify correct colors for endpoint and processor nodes
• Committed in: c1bc32d (Task 2 commit)

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Total deviations: 3 auto-fixed (2 bugs, 1 blocking dependency) Impact on plan: All auto-fixes necessary for correctness. No scope creep.

Issues Encountered

• ELK 0.11.0 has an undeclared runtime dependency on xtext xbase lib -- resolved by adding explicit dependency
• RouteEdge.EdgeType uses FLOW/BRANCH/ERROR/CROSS_ROUTE (not NORMAL as plan implied) -- adapted tests accordingly

User Setup Required

None - no external service configuration required.

Next Phase Readiness

• Diagram rendering complete, ready for execution overlay in UI (v2)
• DiagramRenderer interface can be swapped for alternative implementations
• JSON layout format suitable for client-side interactive rendering

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Phase: 02-transaction-search-diagrams Completed: 2026-03-11