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/Reference/Featherchat.md

@@ -0,0 +1,67 @@
+---
+tags: [reference, wzp]
+type: reference
+---
+
+# FeatherChat: Voice/Video Calling Integration with Warzone Messenger
+
+## Overview
+
+Voice/video calling system designed to integrate with the existing E2E encrypted Warzone messenger. Reuses the same identity, addressing, and key exchange infrastructure.
+
+## Identity Model (reuse, not duplicate)
+
+- **Identity**: 32-byte seed derives both keypairs via HKDF:
+  - Ed25519 (signing)
+  - X25519 (encryption)
+- **Fingerprint**: `SHA-256(Ed25519 public key)[:16]`, displayed as `xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx`
+- **Backup**: BIP39 mnemonic (24 words) for seed recovery
+- **Storage**: Seed encrypted at rest with Argon2id + ChaCha20-Poly1305
+- **Future**: Ethereum address as fingerprint (secp256k1 derived from same BIP39 seed)
+
+## Addressing (reuse)
+
+| Method | Format | Resolution |
+|--------|--------|------------|
+| Local alias | `@manwe` | Server resolves to fingerprint |
+| Federated | `@manwe.b1.example.com` | DNS TXT record → fingerprint + server endpoint |
+| ENS | `@manwe.eth` | Ethereum address → fingerprint (Phase 2-3) |
+| Raw fingerprint | `xxxx:xxxx:...` | Direct lookup (always works as fallback) |
+
+## Key Exchange (can extend)
+
+- **X3DH** for session establishment:
+  - Ed25519 identity key
+  - X25519 ephemeral key
+  - Signed pre-keys
+- **Double Ratchet** for forward secrecy on data channels
+- **Pre-key bundles** stored on server, fetched by callers
+
+## Server Infrastructure
+
+- **Stack**: Rust (axum), sled DB, WebSocket for real-time
+- **Trust model**: Server is untrusted relay — never sees plaintext
+- **Groups**: Named, auto-created, per-member encryption
+- **Federation**: Via DNS TXT records (Phase 3)
+
+## Calling System Requirements
+
+1. **Signaling**: Reuse existing WebSocket connection and identity
+2. **Key derivation**: SRTP/DTLS keys derived from existing X3DH shared secret (or new ephemeral exchange per call)
+3. **Call initiation**: `WireMessage::CallOffer`, `CallAnswer`, `CallIceCandidate` variants
+4. **NAT traversal**: STUN/TURN server integration
+5. **Group calls**: SFU (Selective Forwarding Unit) vs mesh topology for up to 50 users
+6. **Codecs**: Opus for audio, VP8/VP9/AV1 for video
+7. **E2E media encryption**: Insertable streams API (WebRTC) or custom SRTP
+8. **Unified addressing**: A user calls `@manwe` the same way they message `@manwe`
+
+## Degradation Strategy
+
+Calls should degrade gracefully under unreliable/warzone network conditions:
+
+```
+Video (full) → Video (low res) → Audio (high quality) → Audio (low bitrate)
+```
+
+- Support opportunistic cooperation
+- Fall back to TURN/TCP through the existing WebSocket when UDP is blocked