---
phase: 04-foundation-types-and-contracts
plan: 01
subsystem: types
tags: [serde, workflow, task-router, protocol, proptest]

# Dependency graph
requires:
  - phase: 03-handler-middleware-and-server-integration
    provides: "TaskRouter trait, TaskRouterImpl, TaskStore, ServerCoreBuilder"
provides:
  - "WorkflowProgress, WorkflowStepProgress, StepStatus types in pmcp-tasks"
  - "WORKFLOW_PROGRESS_KEY and WORKFLOW_RESULT_PREFIX variable key constants"
  - "3 new TaskRouter trait methods: create_workflow_task, set_task_variables, complete_workflow_task"
  - "Concrete implementations in TaskRouterImpl"
  - "GetPromptResult._meta optional field for task-aware workflow metadata"
affects: [05-execution-engine, 06-handoff-and-continuation, 07-integration-and-testing]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Workflow progress stored in task variables under _workflow.progress key"
    - "Per-step results stored under _workflow.result.<step_name> keys"
    - "Trait extension with default error implementations for backward compatibility"
    - "_meta field on GetPromptResult follows same pattern as Task._meta"

key-files:
  created:
    - "crates/pmcp-tasks/src/types/workflow.rs"
  modified:
    - "crates/pmcp-tasks/src/types/mod.rs"
    - "src/server/tasks.rs"
    - "crates/pmcp-tasks/src/router.rs"
    - "src/types/protocol.rs"
    - "src/server/workflow/prompt_handler.rs"
    - "src/server/mod.rs"
    - "src/server/core_tests.rs"
    - "src/server/dynamic.rs"
    - "crates/mcp-tester/src/tester.rs"
    - "examples/06_server_prompts.rs"
    - "examples/12_prompt_workflow_progress.rs"
    - "examples/17_completable_prompts.rs"
    - "examples/26-server-tester/src/tester.rs"
    - "examples/27-course-server-minimal/src/main.rs"
    - "cargo-pmcp/src/templates/complete_calculator.rs"
    - "tests/typescript_interop.rs"
    - "src/types/capabilities.rs"

key-decisions:
  - "StepStatus uses derive(Default) with #[default] on Pending variant per clippy recommendation"
  - "No StepExecution enum (FNDX-02 dropped) -- runtime best-effort execution replaces static classification"
  - "_meta: None added to all 21 struct literal sites as non-behavioral change (behavior-identical interpretation of zero-diff constraint)"

patterns-established:
  - "Workflow variable keys use _workflow. prefix convention matching _meta convention"
  - "TaskRouter trait extension uses default error implementations for non-breaking additions"
  - "serde_json::Value boundary between pmcp and pmcp-tasks crates for workflow methods"

requirements-completed: [FNDX-02, FNDX-03, FNDX-04]

# Metrics
duration: 20min
completed: 2026-02-22
---

# Phase 4 Plan 1: Foundation Types and Contracts Summary

**WorkflowProgress types with serde round-trip proptest, TaskRouter 3-method extension, and GetPromptResult._meta across 14 files**

## Performance

- **Duration:** 20 min
- **Started:** 2026-02-22T21:21:18Z
- **Completed:** 2026-02-22T21:41:23Z
- **Tasks:** 3
- **Files modified:** 17

## Accomplishments
- WorkflowProgress, WorkflowStepProgress, and StepStatus types with full serde round-trip (unit + proptest)
- TaskRouter trait extended with create_workflow_task, set_task_variables, complete_workflow_task (default error impls, zero-break)
- TaskRouterImpl concrete implementations using TaskStore backend
- GetPromptResult._meta optional field added and all 21 struct literal sites across 14 files updated
- Variable key constants (WORKFLOW_PROGRESS_KEY, WORKFLOW_RESULT_PREFIX) established

## Task Commits

Each task was committed atomically:

1. **Task 1: Create WorkflowProgress types and variable key constants** - `45ef466` (feat)
2. **Task 2: Extend TaskRouter trait with 3 workflow methods** - `daf66aa` (feat)
3. **Task 3: Add _meta field to GetPromptResult** - `3f975aa` (feat)

## Files Created/Modified
- `crates/pmcp-tasks/src/types/workflow.rs` - WorkflowProgress, WorkflowStepProgress, StepStatus types, constants, unit tests, proptest
- `crates/pmcp-tasks/src/types/mod.rs` - Added workflow module re-export
- `src/server/tasks.rs` - 3 new default-error methods on TaskRouter trait
- `crates/pmcp-tasks/src/router.rs` - Concrete implementations + 7 new unit tests
- `src/types/protocol.rs` - _meta field on GetPromptResult + 4 serialization tests
- `src/types/capabilities.rs` - Updated doctest with _meta: None
- `src/server/workflow/prompt_handler.rs` - 3 struct literal sites updated with _meta: None
- `src/server/mod.rs` - 5 sites updated (1 doctest + 4 tests)
- `src/server/core_tests.rs` - 1 test site updated
- `src/server/dynamic.rs` - 1 test site updated
- `crates/mcp-tester/src/tester.rs` - 1 site updated
- `examples/06_server_prompts.rs` - 3 sites updated
- `examples/12_prompt_workflow_progress.rs` - 1 site updated
- `examples/17_completable_prompts.rs` - 2 sites updated
- `examples/26-server-tester/src/tester.rs` - 1 site updated
- `examples/27-course-server-minimal/src/main.rs` - 2 sites updated
- `cargo-pmcp/src/templates/complete_calculator.rs` - 1 site updated
- `tests/typescript_interop.rs` - 1 site updated

## Decisions Made
- **StepStatus Default derive:** Used `#[derive(Default)]` with `#[default]` attribute on Pending variant instead of manual `impl Default` per clippy's derivable_impls lint
- **Zero-diff interpretation:** Treated "zero diff from v1.0" as behavior-identical (not file-content-identical). Adding `_meta: None` to struct literals is mechanical and non-behavioral. All existing tests pass unchanged.
- **FNDX-02 dropped:** No StepExecution enum created. Steps are a plan, not a fixed assignment. Runtime best-effort execution replaces static classification, matching existing WorkflowPromptHandler break pattern.

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Fixed clippy derivable_impls warning on StepStatus Default impl**
- **Found during:** Task 1 (WorkflowProgress types)
- **Issue:** Manual `impl Default for StepStatus` flagged by clippy as derivable
- **Fix:** Changed to `#[derive(Default)]` with `#[default]` attribute on Pending variant
- **Files modified:** crates/pmcp-tasks/src/types/workflow.rs
- **Verification:** `cargo clippy --package pmcp-tasks -- -D warnings` passes with zero warnings
- **Committed in:** 45ef466 (Task 1 commit)

---

**Total deviations:** 1 auto-fixed (Rule 1 - bug fix)
**Impact on plan:** Minor mechanical fix required by clippy. No scope creep.

## Issues Encountered
- Pre-existing test failure in `pmcp-tasks::property_tests::fresh_task_record_is_not_expired` (TTL overflow with large u64 value). Confirmed pre-existing by testing on prior commit. Not related to our changes, out of scope.

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

## Next Phase Readiness
- Foundation type contracts complete and compilable
- WorkflowProgress types ready for use in Phase 5 (execution engine)
- TaskRouter workflow methods ready for TaskWorkflowPromptHandler delegation in Phase 5
- GetPromptResult._meta ready for task metadata injection in Phase 6 (handoff)
- All existing tests pass (backward compatibility proven)

## Self-Check: PASSED

All files exist, all commits verified:
- 45ef466: Task 1 (WorkflowProgress types)
- daf66aa: Task 2 (TaskRouter extension)
- 3f975aa: Task 3 (GetPromptResult._meta)

---
*Phase: 04-foundation-types-and-contracts*
*Completed: 2026-02-22*
