---
phase: 08-quality-polish-and-test-coverage
plan: 01
subsystem: workflow
tags: [diagnostics, schema-validation, pause-reason, tracing, quality]

# Dependency graph
requires:
  - phase: 05-pause-reason-and-task-execution
    provides: PauseReason enum and classify_resolution_failure function
provides:
  - params_satisfy_tool_schema returning Vec<String> of actual missing field names
  - Full PauseReason coverage on all execution loop break paths
  - tracing::warn! observability on error paths
affects: [08-quality-polish-and-test-coverage]

# Tech tracking
tech-stack:
  added: []
  patterns: [collect-all-missing-fields, no-silent-breaks, tracing-on-error-paths]

key-files:
  created: []
  modified:
    - src/server/workflow/prompt_handler.rs
    - src/server/workflow/task_prompt_handler.rs
    - examples/11_progress_countdown.rs
    - examples/12_prompt_workflow_progress.rs

key-decisions:
  - "Route resolve_tool_parameters failure through classify_resolution_failure for accurate dependency diagnostics"
  - "Direct PauseReason::UnresolvableParams for params_satisfy_tool_schema Err (schema lookup error, not resolution)"

patterns-established:
  - "Every break in the execution loop must set a PauseReason -- no silent breaks allowed"
  - "Schema validation returns all missing fields, not just the first"

requirements-completed: []

# Metrics
duration: 8min
completed: 2026-02-23
---

# Phase 8 Plan 1: SchemaMismatch Diagnostic Accuracy and Silent Break Elimination Summary

**params_satisfy_tool_schema now returns Vec<String> of actual missing field names, and all execution loop break paths set PauseReason with tracing::warn! observability**

## Performance

- **Duration:** 8 min
- **Started:** 2026-02-23T19:55:12Z
- **Completed:** 2026-02-23T20:03:14Z
- **Tasks:** 2
- **Files modified:** 4

## Accomplishments
- Changed params_satisfy_tool_schema return type from Result<bool> to Result<Vec<String>> collecting ALL missing required field names
- PauseReason::SchemaMismatch.missing_fields now contains real field names from schema check (replaces hardcoded ["unknown"])
- Both silent break paths (resolve_tool_parameters failure and params_satisfy_tool_schema Err) now set PauseReason before breaking
- Added tracing::warn! on both error paths for observability

## Task Commits

Each task was committed atomically:

1. **Task 1: Change params_satisfy_tool_schema return type and adapt both callers** - `fb3847c` (fix)
2. **Task 2: Fix silent breaks with PauseReason and tracing** - `2bd60fa` (fix)

## Files Created/Modified
- `src/server/workflow/prompt_handler.rs` - Changed params_satisfy_tool_schema to return Vec<String>, adapted inner handler caller
- `src/server/workflow/task_prompt_handler.rs` - Adapted task handler caller with missing.clone(), fixed both silent breaks with PauseReason and tracing
- `examples/11_progress_countdown.rs` - Fixed pre-existing missing _task_id field in RequestMeta
- `examples/12_prompt_workflow_progress.rs` - Fixed pre-existing missing _task_id field in RequestMeta

## Decisions Made
- Route resolve_tool_parameters failure through classify_resolution_failure (same information available as announcement failure path, provides accurate dependency vs generic diagnostics)
- Direct PauseReason::UnresolvableParams for params_satisfy_tool_schema Err path (schema lookup error, not a resolution failure)
- Used `Ok(ref missing) if !missing.is_empty()` match guard pattern for idiomatic Rust handling of the new Vec<String> return

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Fixed pre-existing RequestMeta _task_id field in examples**
- **Found during:** Task 1 (verification step)
- **Issue:** examples/11_progress_countdown.rs and examples/12_prompt_workflow_progress.rs were missing the `_task_id` field added to RequestMeta in a previous phase, causing compilation failure when running `cargo test --package pmcp -- workflow`
- **Fix:** Added `_task_id: None` to all RequestMeta struct literals in both example files
- **Files modified:** examples/11_progress_countdown.rs, examples/12_prompt_workflow_progress.rs
- **Verification:** `cargo test --package pmcp -- workflow` passes (171 tests)
- **Committed in:** fb3847c (part of Task 1 commit)

---

**Total deviations:** 1 auto-fixed (1 blocking)
**Impact on plan:** Pre-existing compilation issue in examples blocked test verification. Fix is minimal and correct.

## Issues Encountered
None beyond the pre-existing example compilation issue documented above.

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

## Next Phase Readiness
- SchemaMismatch diagnostics now accurate with real field names in _meta JSON
- All execution loop break paths have PauseReason coverage
- Ready for plan 02 (remaining quality polish items)

## Self-Check: PASSED

All files exist on disk and all commit hashes found in git log.

---
*Phase: 08-quality-polish-and-test-coverage*
*Completed: 2026-02-23*
