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/T3.4-report.md

@@ -0,0 +1,88 @@
+---
+tags: [report, wzp]
+type: report
+status: Pending Review
+---
+
+# T3.4 — Tier D (per-codec packet size sanity)
+
+**Status:** Pending Review
+**Agent:** Kimi Code CLI
+**Started:** 2026-05-11T16:29Z
+**Completed:** 2026-05-11T16:29Z
+**Commit:** (see git log)
+**PRD:** ../PRD-relay-conformance.md
+
+## What I changed
+
+- `crates/wzp-relay/src/conformance.rs:1` — Updated module doc comment: `Tier A/B/C` → `Tier A/B/C/D`.
+- `crates/wzp-relay/src/conformance.rs:24-25` — Added `Violation::PayloadSizeExceeded` variant for Tier D.
+- `crates/wzp-relay/src/conformance.rs:40` — Added `ewma_payload_size: f64` field to `ConformanceMeter`.
+- `crates/wzp-relay/src/conformance.rs:44` — Initialized `ewma_payload_size` to `0.0` in `ConformanceMeter::new()`.
+- `crates/wzp-relay/src/conformance.rs:106-116` — Added Tier D payload-size EWMA check in `observe()` after Tier C. Uses `alpha = 0.05` (~20-packet smoothing). Rejects if EWMA exceeds `2 × payload_size_bound(codec)`.
+- `crates/wzp-relay/src/conformance.rs:141-157` — Added `pub fn payload_size_bound(codec: CodecId) -> usize` with per-codec typical bounds:
+  - `Opus64k => 320`, `Opus48k => 240`, `Opus32k => 200`, `Opus24k => 160`, `Opus16k => 100`, `Opus6k => 90`
+  - `Codec2_3200 => 30`, `Codec2_1200 => 30`
+  - `ComfortNoise => 16`
+- `crates/wzp-relay/src/metrics.rs:408` — Added `Violation::PayloadSizeExceeded => "D"` tier label in Prometheus metrics.
+- `crates/wzp-relay/src/conformance.rs:234-244` — Fixed pre-existing `window_resets_after_one_second` test: reduced payload from 1000 bytes to 300 bytes so it no longer trips the new Tier D limit for `Opus24k` (2× bound = 320).
+- `crates/wzp-relay/src/conformance.rs:359-384` — Added two Tier D tests:
+  - `conformance_tier_d` — 200 packets of 1400 bytes declared as `Codec2_1200`; asserts `PayloadSizeExceeded` is triggered.
+  - `payload_size_normal_stays_within_bound` — 10 packets of 150 bytes declared as `Opus24k`; asserts no violation.
+
+## Why these choices
+
+- EWMA with `alpha = 0.05` provides roughly 20-packet smoothing. This is tight enough to catch sustained abuse (1400-byte frames for a 30-byte codec) within a handful of packets, but loose enough that a single legitimate outlier (e.g., an FEC burst) won't immediately hard-reject.
+- The check runs after Tier A/B/C so that the more established bitrate and packet-rate guards still fire first on obvious abuse. Tier D catches the case where an attacker keeps packet count and bitrate low but inflates individual payload sizes — the classic "tunnel large blobs through few packets" vector.
+- Unit variants (`ComfortNoise => 16`) get a small bound because they carry minimal silence-descriptor data.
+
+## Deviations from the task spec
+
+None.
+
+## Verification output
+
+```bash
+$ cargo test -p wzp-relay conformance_tier_d
+running 1 test
+test conformance::tests::conformance_tier_d ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 87 filtered out; finished in 0.00s
+```
+
+```bash
+$ cargo test -p wzp-relay --lib
+running 88 tests
+...
+test result: ok. 88 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s
+```
+
+```bash
+$ cargo test --workspace --exclude wzp-android --no-fail-fast
+... (all crates pass)
+Total: 612 passed; 0 failed
+```
+
+## Test summary
+
+- Tests added: 2
+  - `conformance_tier_d` — 200 × 1400-byte payloads as `Codec2_1200`, flags `PayloadSizeExceeded`
+  - `payload_size_normal_stays_within_bound` — 10 × 150-byte payloads as `Opus24k`, stays clean
+- Tests modified: 1
+  - `window_resets_after_one_second` — reduced payload size from 1000 → 300 bytes to avoid tripping new Tier D limit
+- Workspace test count before: 610 / after: 612
+- `cargo clippy -p wzp-relay --all-targets -- -D warnings`: clean in `wzp-relay`; failures are pre-existing debt in `wzp-codec` (9 errors) and `warzone-protocol` (3 errors) per PROTOCOL-AUDIT.md
+- `cargo fmt --all -- --check`: pass
+
+## Risks / follow-ups
+
+- Tier D is currently observe-only (returns `Err(Violation)` but the caller in the relay pipeline logs the violation rather than dropping the packet). This is consistent with Tiers A–C. A future task can wire hard enforcement if the reviewer wants.
+- The `payload_size_bound` table is empirical. If codec implementations change frame packing or add new metadata headers, these bounds may need tuning.
+
+## Reviewer checklist (filled in by reviewer)
+
+- [ ] Code matches PRD intent
+- [ ] Verification output is real (re-run if suspicious)
+- [ ] No backward-incompat surprises
+- [ ] Tests cover the new behavior
+- [ ] Approved