docs: protocol audit 2026-05-25, update architecture + Obsidian vault

Audit:
- docs/AUDIT-2026-05-25.md: full protocol audit covering 8 findings
  (4 critical, 2 high, 5 medium, 4 low) with code references and fix
  effort estimates
- vault/Audit/Tasks.md: Obsidian Tasks plugin file tracking all audit
  items with priorities, due dates, and per-step checklists

Architecture docs updated for Wire format v2 and Wave 5/6 features:
- ARCHITECTURE.md: adds wzp-video to dependency graph and project
  structure; wire format updated to v2 (16B header, 5B MiniHeader);
  relay concurrency section corrected (DashMap+RwLock is current, not
  a future optimization); test count 571→702; Android note
- PROGRESS.md: Wave 5 and Wave 6 sections appended; test count 372→702;
  current status and open blockers as of 2026-05-25
- ROAD-TO-VIDEO.md: implementation status table inserted (✅/🟡/🔴/🔲
  per phase); 6-step critical path to first video call
- WZP-SPEC.md: MediaHeader updated to v2 (16B byte-aligned); MiniHeader
  updated to 5B with seq_delta; codec IDs 9-12 added (H.264/H.265/AV1);
  version negotiation section added

Obsidian vault (vault/):
- 114 files across Architecture/, PRDs/, Reports/, Android/,
  Reference/, Audit/ with YAML frontmatter
- 00 - Home.md index note with wiki links
- .obsidian/app.json config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vault/Reports/T1.2-report.md

@@ -0,0 +1,102 @@
+---
+tags: [report, wzp]
+type: report
+status: Approved
+---
+
+# T1.2 — Add `MediaType` enum
+
+**Status:** Approved
+**Agent:** Kimi Code CLI
+**Started:** 2026-05-11T06:55Z
+**Completed:** 2026-05-11T07:08Z
+**Commit:** see git log
+**PRD:** ../PRD-wire-format-v2.md
+
+## What I changed
+
+- `crates/wzp-proto/src/media_type.rs:1-55` — created new module with `MediaType` enum (`Audio=0`, `Video=1`, `Data=2`, `Control=3`), `to_wire()`, `from_wire()`, and two unit tests
+- `crates/wzp-proto/src/lib.rs:18` — added `pub mod media_type;`
+- `crates/wzp-proto/src/lib.rs:28` — added `pub use media_type::MediaType;`
+- `crates/wzp-proto/src/packet.rs:4` — added `use crate::MediaType;`
+- `crates/wzp-proto/src/packet.rs:168` — changed `MediaHeaderV2.media_type` from `u8` to `MediaType`, resolving the `TODO(T1.2)`
+- `crates/wzp-proto/src/packet.rs:184` — `write_to` now calls `self.media_type.to_wire()`
+- `crates/wzp-proto/src/packet.rs:202` — `read_from` now uses `MediaType::from_wire(buf.get_u8())?`
+- `crates/wzp-proto/src/packet.rs:1292` — updated `media_header_v2_roundtrip` test to use `MediaType::Audio`
+
+## Why these choices
+
+Followed steps T1.2.1 through T1.2.2 without deviation. Since `MediaType` now exists, I also resolved the `TODO(T1.2)` placeholder left in `MediaHeaderV2` during T1.1 so the v2 header is internally consistent before moving on.
+
+## Deviations from the task spec
+
+None.
+
+## Verification output
+
+```bash
+$ cargo test -p wzp-proto media_type
+running 2 tests
+test media_type::tests::media_type_roundtrip ... ok
+test media_type::tests::media_type_unknown_rejected ... ok
+
+test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 106 filtered out; finished in 0.00s
+```
+
+```bash
+$ cargo test -p wzp-proto media_header_v2_roundtrip
+running 1 test
+test packet::tests::media_header_v2_roundtrip ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 107 filtered out; finished in 0.00s
+```
+
+```bash
+$ cargo build -p wzp-proto -p wzp-codec -p wzp-fec -p wzp-crypto -p wzp-transport -p wzp-relay -p wzp-client -p wzp-web -p wzp-native
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 15.31s
+```
+
+```bash
+$ cargo test -p wzp-proto -p wzp-codec -p wzp-fec -p wzp-crypto -p wzp-transport -p wzp-relay -p wzp-client -p wzp-web -p wzp-native --no-fail-fast
+...
+test result: ok. 567 passed; 0 failed; ...
+```
+
+```bash
+$ cargo clippy -p wzp-proto --all-targets -- -D warnings
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.57s
+```
+
+```bash
+$ cargo fmt --all -- --check
+# (clean)
+```
+
+## Test summary
+
+- Tests added: 2 (`media_type_roundtrip`, `media_type_unknown_rejected`)
+- Tests modified: 1 (`media_header_v2_roundtrip` — now uses `MediaType::Audio`)
+- Workspace test count before: 565 pass / 0 fail (non-Android subset)
+- Workspace test count after: 567 pass / 0 fail (non-Android subset)
+- `cargo clippy -p wzp-proto --all-targets -- -D warnings`: pass
+- `cargo fmt --all -- --check`: pass
+
+## Risks / follow-ups
+
+None.
+
+## Reviewer checklist (filled in by reviewer)
+
+- [x] Code matches PRD intent
+- [x] Verification output is real (re-run if suspicious) — re-ran `cargo test -p wzp-proto` (112 passed across 2 suites), clippy + fmt clean.
+- [x] No backward-incompat surprises
+- [x] Tests cover the new behavior
+- [x] Approved
+
+### Reviewer notes (2026-05-11)
+
+Approved. Bonus that the agent resolved the `TODO(T1.2)` placeholder inside `MediaHeaderV2.media_type` in the same commit — keeps the v2 header internally consistent and unblocks downstream tasks cleanly. That extension was disclosed under "Why these choices" — exactly the right move.
+
+One small follow-up:
+
+1. **T1.2.1 — Add rustdoc on `MediaType` variants and methods.** Same rustdoc-coverage concern as T1.1.1 — coding standard #9. Non-blocking.