---
phase: 36-unify-uimimetype-and-extendeduimimetype-with-from-bridge
verified: 2026-03-06T22:00:00Z
status: passed
score: 4/4 must-haves verified
re_verification: false
---

# Phase 36: Unify UIMimeType and ExtendedUIMimeType with From Bridge — Verification Report

**Phase Goal:** Add From/TryFrom conversion traits between UIMimeType and ExtendedUIMimeType so code can seamlessly convert across the feature-gate boundary
**Verified:** 2026-03-06T22:00:00Z
**Status:** passed
**Re-verification:** No — initial verification

## Goal Achievement

### Observable Truths

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 1 | UIMimeType values convert infallibly to ExtendedUIMimeType via `.into()` | VERIFIED | `impl From<crate::types::ui::UIMimeType> for ExtendedUIMimeType` at line 745 in `src/types/mcp_apps.rs`; test `test_from_ui_mime_type` passes |
| 2 | ExtendedUIMimeType shared variants convert back to UIMimeType via `try_from()` | VERIFIED | `impl TryFrom<ExtendedUIMimeType> for crate::types::ui::UIMimeType` at line 761; test `test_try_from_extended_shared` passes |
| 3 | ExtendedUIMimeType extended-only variants fail conversion to UIMimeType with descriptive error | VERIFIED | `other => Err(format!("Cannot convert {} to UIMimeType (extended-only variant)", other))` at line 769; test `test_try_from_extended_fails` passes for HtmlPlain, UriList, RemoteDom, RemoteDomReact |
| 4 | Round-trip UIMimeType -> ExtendedUIMimeType -> UIMimeType preserves the original value | VERIFIED | test `test_mime_type_round_trip` passes for all 3 shared variants |

**Score:** 4/4 truths verified

### Required Artifacts

| Artifact | Expected | Status | Details |
|----------|----------|--------|---------|
| `src/types/mcp_apps.rs` | `From<UIMimeType> for ExtendedUIMimeType` impl | VERIFIED | Explicit 3-arm match, no wildcards, lines 745-753 |
| `src/types/mcp_apps.rs` | `TryFrom<ExtendedUIMimeType> for UIMimeType` impl | VERIFIED | Explicit 7-arm match (3 Ok, 4 Err), lines 761-775 |

### Key Link Verification

| From | To | Via | Status | Details |
|------|----|-----|--------|---------|
| `src/types/mcp_apps.rs` | `src/types/ui.rs` | `From/TryFrom` trait impls using `crate::types::ui::UIMimeType` path | WIRED | Full path `crate::types::ui::UIMimeType` appears at lines 745, 746, 748, 749, 750, 761; avoids ambiguous use-imports |

### Requirements Coverage

| Requirement | Source Plan | Description | Status | Evidence |
|-------------|-------------|-------------|--------|----------|
| MIME-BRIDGE-01 | 36-01-PLAN.md | Bidirectional From/TryFrom bridge between UIMimeType and ExtendedUIMimeType | SATISFIED | Both impls present in `src/types/mcp_apps.rs`, 4 tests pass, zero clippy warnings |

**Note:** MIME-BRIDGE-01 is a phase-local requirement ID. It does not appear in `.planning/REQUIREMENTS.md` because that file covers v1.6 CLI DX requirements (phases 27 and below). Phases 35+ establish their own local requirement IDs in plan frontmatter. There are no orphaned requirements — the REQUIREMENTS.md has no entries for phase 36 or MIME-type concerns.

### Anti-Patterns Found

None. No TODO/FIXME/HACK/PLACEHOLDER comments in either modified file. No empty implementations. No stubs.

### Human Verification Required

None. All goal behaviors are verifiable programmatically:
- Conversion trait impls exist and are substantive (explicit match arms covering all variants)
- All 4 tests pass under `--features mcp-apps`
- Clippy passes clean with `-D warnings`
- Non-feature build also compiles cleanly (bridge is in `mcp_apps.rs`, which is always compiled, but From/TryFrom only reference `crate::types::ui::UIMimeType` which is always available)

### Additional Quality Notes

- Match arms are explicit (no wildcards) — compiler will flag missing arms when new variants are added to either enum.
- Error type is `String`, consistent with `FromStr::Err` on both enums.
- The `src/types/ui.rs` fix (removing redundant `.into_iter()` in `map.extend()`) was a legitimate clippy fix, not scope creep.
- Commits 8735351 (failing tests) and dfae0cf (impl + fix) both exist in git history, confirming TDD RED-GREEN discipline was followed.

### Gaps Summary

No gaps. All must-haves are satisfied. The phase goal is fully achieved.

---

_Verified: 2026-03-06T22:00:00Z_
_Verifier: Claude (gsd-verifier)_
