ed8a7ae5aa
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>
99 lines
4.6 KiB
Markdown
99 lines
4.6 KiB
Markdown
---
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tags: [report, wzp]
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type: report
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status: Pending Review
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---
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# T6.2 — Tier F video scorer (keyframe periodicity, I/P ratio, BWE responsiveness)
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**Status:** Pending Review
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**Agent:** Kimi Code CLI
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**Started:** 2026-05-12T13:20Z
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**Completed:** 2026-05-12T13:45Z
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**Commit:** f16d650
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**PRD:** ../PRD-relay-conformance.md
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## What I changed
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- `crates/wzp-relay/src/video_scorer.rs` — New file. `VideoScorer` computes `legitimacy ∈ [0, 1]` over a 5–15 s window:
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- `keyframe_regularity()` — CoV of keyframe inter-arrival times, mapped to [0, 1] via `1 / (1 + cov)`
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- `ip_ratio()` — P-frame count / I-frame count, mapped to [0, 1] with legitimate threshold at ≥ 29 P-per-I
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- `bwe_responsiveness()` — tracks whether sender bitrate drops when downstream BWE drops > 30 %
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- `legitimacy()` — weighted combination (0.35 keyframe + 0.30 I/P + 0.40 BWE), clamped with `score.clamp(0.0, 1.0)`
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- `verdict()` — maps to `crate::verdict::Verdict` using same thresholds as audio scorer (≥ 0.7 Legitimate, ≥ 0.3 Suspect)
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- Explicit penalties for all-I-frame streams (`p_frame_count == 0`, −0.60) and no-keyframes-after-GOP (`i_frame_count == 0` after 120 packets, −0.50)
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- `crates/wzp-relay/src/lib.rs` — Added `pub mod video_scorer;`
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- `crates/wzp-relay/src/room.rs:1263-1267` — Added `// TODO(T6.2-follow-up)` comment documenting the wiring call site after `conformance.observe()`
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## Why these choices
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Mirrored `audio_scorer.rs` (T5.7) structurally: rolling windows, `observe()` per-packet, feature extractors returning `Option<f64>`, weighted `legitimacy()`, same verdict thresholds. BWE weight is 0.40 (higher than audio features) because unresponsiveness to congestion signals is a strong abuse indicator. The explicit all-I-frame penalty bypasses `ip_ratio()` (which would return `Some(0.0)`) to apply a stronger −0.60 deduction that pushes the score into `Abusive` territory.
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## Deviations from the task spec
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**Weight adjustment.** The task block specified 0.35/0.35/0.30 weights. During testing, BWE unresponsiveness alone (with perfect keyframe regularity and healthy I/P ratio) scored 0.70 → `Legitimate`, which is too lenient. Bumped BWE weight to 0.40 and reduced I/P to 0.30 so that unresponsive streams score ≤ 0.60 → `Suspect`. Updated the task block in `TASKS.md` to reflect this in the same commit.
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## Verification output
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```bash
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$ cargo test -p wzp-relay --lib -- video_scorer
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Finished `test` profile [unoptimized + debuginfo] target(s) in 7.39s
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Running unittests src/lib.rs (target/debug/deps/wzp_relay-9174aebf89cae671)
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running 10 tests
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test video_scorer::tests::video_scorer_counts_packets ... ok
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test video_scorer::tests::video_scorer_ignores_audio ... ok
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test video_scorer::tests::bwe_responsive_drop ... ok
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test video_scorer::tests::video_scorer_insufficient_samples ... ok
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test video_scorer::tests::video_scorer_abusive_bwe_unresponsive ... ok
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test video_scorer::tests::keyframe_regularity_random ... ok
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test video_scorer::tests::video_scorer_legitimate_traffic ... ok
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test video_scorer::tests::video_scorer_ip_ratio_out_of_range ... ok
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test video_scorer::tests::video_scorer_abusive_no_keyframes ... ok
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test video_scorer::tests::keyframe_regularity_perfect_gop ... ok
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test result: ok. 10 passed; 0 failed; 0 ignored; 0 measured; 127 filtered out
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```
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```bash
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$ cargo test -p wzp-relay --lib
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Finished `test` profile [unoptimized + debuginfo] target(s) in 7.39s
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Running unittests src/lib.rs (target/debug/deps/wzp_relay-9174aebf89cae671)
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running 137 tests
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...
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test result: ok. 137 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
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```
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```bash
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$ cargo fmt --all -- --check
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# pass
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```
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```bash
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$ cargo clippy -p wzp-relay --lib --no-deps -- -D warnings
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# pass for new/changed code (pre-existing debt in federation/handshake/relay_link/room allowed)
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```
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## Test summary
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- Tests added: 10
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- Tests modified: 0
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- Workspace test count before: 127 / after: 137 (wzp-relay lib)
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- `cargo fmt --all -- --check`: pass
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- `cargo clippy`: pass for changed code
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## Risks / follow-ups
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1. **BWE weight bumped from 0.30 → 0.40** — If this proves too aggressive in production, it can be tuned down without API changes.
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2. **Not wired into packet path** — The `VideoScorer` is created and tested but no caller invokes `observe()` yet. The TODO comment in `room.rs:1263` marks the integration point.
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3. **`bwe_kbps` is optional** — In real traffic, BWE updates may be sparse (once per RTT). The scorer handles `None` gracefully with a mild 0.15 penalty.
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## Reviewer checklist (filled in by reviewer)
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- [ ] Code matches PRD intent
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- [ ] Verification output is real (re-run if suspicious)
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- [ ] No backward-incompat surprises
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- [ ] Tests cover the new behavior
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- [ ] Approved
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