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/T3.2-report.md

@@ -0,0 +1,82 @@
+---
+tags: [report, wzp]
+type: report
+status: Pending Review
+---
+
+# T3.2 — Document `timestamp_ms` rebase across rekey (W3)
+
+**Status:** Pending Review
+**Agent:** Kimi Code CLI
+**Started:** 2026-05-11T21:15Z
+**Completed:** 2026-05-11T21:25Z
+**Commit:** (see git log)
+**PRD:** ../PRD-protocol-hardening.md
+
+## What I changed
+
+- `crates/wzp-proto/src/packet.rs` — Updated doc comment on `MediaHeader::timestamp`:
+  ```rust
+  /// Milliseconds since session start. Monotonic for the full session lifetime;
+  /// NOT reset by rekey (rekey changes only key material, not framing state).
+  pub timestamp: u32,
+  ```
+
+- `crates/wzp-crypto/src/rekey.rs` — Added inline comment on `perform_rekey()`:
+  ```rust
+  /// NOTE: Rekeying changes **only** the symmetric key material.  Sequence
+  /// numbers and timestamps in the media framing layer (e.g. `MediaHeader`)
+  /// are untouched — they continue monotonically across the rekey boundary.
+  ```
+
+- `docs/WZP-SPEC.md` — Updated `timestamp_ms` field description:
+  ```
+  | timestamp_ms | 32 | ms since session start. Monotonic across the full session; **not reset by rekey** |
+  ```
+
+- `crates/wzp-client/tests/long_session.rs` — Added `rekey_timestamp_monotonic` test:
+  - Simulates a 3000-frame session with two conceptual rekey boundaries at frames 1000 and 2000.
+  - Collects all `MediaHeader::timestamp` values across the three phases.
+  - Asserts strict monotonicity (non-decreasing) with `windows(2)`.
+  - Sanity-checks that at least 3000 timestamps were collected.
+
+## Why these choices
+
+The test uses `CallEncoder` (which owns `timestamp_ms`) rather than `ChaChaSession` (which owns `RekeyManager`) because the property we care about is at the **framing layer**: regardless of what happens in crypto, the media header timestamps must not jump backwards or reset. `CallEncoder` is the component that actually emits timestamps, and it has no knowledge of rekeying — which is exactly the invariant we want to verify.
+
+## Deviations from the task spec
+
+None.
+
+## Verification output
+
+```bash
+$ cargo test -p wzp-client --test long_session
+running 4 tests
+test rekey_timestamp_monotonic ... ok
+test long_session_no_drift ... ok
+test long_session_with_simulated_loss ... ok
+test long_session_stats_consistency ... ok
+
+test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 14.62s
+```
+
+## Test summary
+
+- Tests added: 1
+  - `rekey_timestamp_monotonic` — 3000-frame session, two rekey boundaries, verifies timestamp monotonicity
+- Tests modified: 0
+- `wzp-client` integration test count: 4 (was 3 before T3.2)
+- `cargo fmt --all -- --check`: pass
+
+## Risks / follow-ups
+
+- The test simulates rekeys conceptually (phase boundaries) rather than invoking `RekeyManager::perform_rekey()` directly. This is correct because `CallEncoder` doesn't touch crypto state; a more integration-level test could be added later if the encoder/decoder ever gains explicit rekey hooks.
+
+## Reviewer checklist (filled in by reviewer)
+
+- [ ] Code matches PRD intent
+- [ ] Verification output is real
+- [ ] No backward-incompat surprises
+- [ ] Tests cover the new behavior
+- [ ] Approved