---
phase: 39-add-deep-merge-for-ui-meta-key-to-prevent-collision
plan: 02
subsystem: api
tags: [deep-merge, typed-tools, meta-collision, builder-pattern]

requires:
  - phase: 39-add-deep-merge-for-ui-meta-key-to-prevent-collision
    plan: 01
    provides: deep_merge function and with_meta_entry builder
provides:
  - All four tool types use deep_merge for _meta construction
  - TypedToolWithOutput gains with_ui() builder method
affects: []

tech-stack:
  added: []
  patterns: [deep_merge in metadata/info for collision-free _meta]

key-files:
  created: []
  modified:
    - src/server/typed_tool.rs
    - src/server/wasm_typed_tool.rs

key-decisions:
  - "TypedToolWithOutput::with_ui() mirrors TypedTool::with_ui() exactly for API consistency"
  - "All four tool types now use identical deep_merge pattern in metadata()/info()"

requirements-completed: [MERGE-02]

duration: 3min
completed: 2026-03-07
---

# Phase 39 Plan 02: Migrate All Tool Types to deep_merge Summary

**All four tool types (TypedTool, TypedSyncTool, TypedToolWithOutput, WasmTypedTool) now use deep_merge for _meta construction, eliminating collision risk; TypedToolWithOutput gains with_ui() builder**

## Performance

- **Duration:** 3 min
- **Started:** 2026-03-07T00:07:05Z
- **Completed:** 2026-03-07T00:09:39Z
- **Tasks:** 3
- **Files modified:** 2

## Accomplishments
- Updated TypedTool::metadata() and TypedSyncTool::metadata() to use deep_merge pattern
- Added `ui_resource_uri` field and `with_ui()` builder to TypedToolWithOutput
- Fixed TypedToolWithOutput::metadata() from hardcoded `_meta: None` to deep_merge-based merge
- Updated WasmTypedTool::info() to use deep_merge pattern
- Added 3 new tests for TypedToolWithOutput UI metadata behavior
- All 720 library tests pass, zero clippy warnings

## Task Commits

Each task was committed atomically:

1. **Task 1: Update TypedTool and TypedSyncTool metadata() to use deep_merge** - `aa5eb98` (feat)
2. **Task 2: Add with_ui() to TypedToolWithOutput and fix metadata() merge** - `ec8c59c` (feat)
3. **Task 3: Update WasmTypedTool info() to use deep_merge** - `493f99f` (feat)

## Files Created/Modified
- `src/server/typed_tool.rs` - Updated metadata() for TypedTool, TypedSyncTool, TypedToolWithOutput; added with_ui() and ui_resource_uri to TypedToolWithOutput; 3 new tests
- `src/server/wasm_typed_tool.rs` - Updated info() for WasmTypedTool to use deep_merge pattern

## Decisions Made
- TypedToolWithOutput::with_ui() mirrors TypedTool::with_ui() exactly for API consistency
- All four tool types now use identical deep_merge pattern in metadata()/info()

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None.

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Phase 39 is complete: deep_merge infrastructure (Plan 01) and migration (Plan 02) both shipped
- All tool types now support composable _meta without collision risk

## Self-Check: PASSED

- All source files exist
- All 3 commits verified (aa5eb98, ec8c59c, 493f99f)
- 720 tests pass, zero clippy warnings
- CallToolResult/GetPromptResult untouched (scope guard verified)

---
*Phase: 39-add-deep-merge-for-ui-meta-key-to-prevent-collision*
*Completed: 2026-03-07*
