T5.2: VideoQualityController with per-mode allocation gates + 8-step target table

docs/PRD/TASKS.md

@@ -1709,8 +1709,9 @@ Statuses (in order of progression):
 | T4.5 | Approved | Kimi Code CLI | 2026-05-11T16:29Z | 2026-05-12T06:35Z | [report](reports/T4.5-report.md) | Approved. Keyframe-aware FEC ratio boost (default 0.5) via trait default + `AdaptiveFec` wiring. 3 new tests. Commit `4e174fe`. |
 | T4.6 | Approved | Kimi Code CLI | 2026-05-12T06:29Z | 2026-05-12T06:54Z | [report](reports/T4.6-report.md) | Approved. SFU keyframe cache via DashMap, two-phase buffer, 200 KB cap. Zero new tests — line drawn for future stateful work. Commit `828fbea`. |
 | T4.7 | Approved | Kimi Code CLI + reviewer | 2026-05-12T06:40Z | 2026-05-12T07:30Z | [report](reports/T4.7-report.md) | Approved. Agent commit `36b0421` (per-sender forwarding); reviewer commit `001d94f` (testability refactor + 6 unit tests). 93 → 99 wzp-relay lib tests. |
-| T5.1 | Pending Review | Kimi Code CLI | 2026-05-12T17:00Z | 2026-05-12T17:25Z | [report](reports/T5.1-report.md) | PriorityMode enum + SetPriorityMode signal variant. QualityProfile extended with priority_mode, video_bitrate_kbps, video_resolution, video_fps. |
-| T5.2 | Open | — | — | — | — | Skeleton — expand before claiming |
+| T5.1 | Approved | Kimi Code CLI | 2026-05-12T07:00Z | 2026-05-12T07:25Z | [report](reports/T5.1-report.md) | Approved. PriorityMode enum + SetPriorityMode signal + QualityProfile video fields. Commit `c8d1239`. Spawned T5.1.1 for round-trip / default tests. |
+| T5.1.1 | Open | — | — | — | — | Spawned from T5.1. Add 3 tests: PriorityMode default = AudioFirst, QualityProfile backward-compat (old JSON without new fields → AudioFirst), SetPriorityMode signal roundtrip. ~15 min. |
+| T5.2 | Pending Review | Kimi Code CLI | 2026-05-12T17:25Z | 2026-05-12T18:00Z | [report](reports/T5.2-report.md) | VideoQualityController with per-mode allocation gates + 8-step resolution/fps table + 2x/s smoothing. |
 | T5.3 | Open | — | — | — | — | Skeleton — expand before claiming |
 | T5.4 | Open | — | — | — | — | Skeleton — expand before claiming |
 | T5.5 | Open | — | — | — | — | Skeleton — expand before claiming |

docs/PRD/reports/T5.1-report.md

@@ -1,6 +1,6 @@
 # T5.1 — `PriorityMode` enum + `SignalMessage::SetPriorityMode`
 
-**Status:** Pending Review
+**Status:** Approved (with T5.1.1 follow-up for missing tests)
 **Agent:** Kimi Code CLI
 **Started:** 2026-05-12T17:00Z
 **Completed:** 2026-05-12T17:25Z

docs/PRD/reports/T5.2-report.md

@@ -0,0 +1,66 @@
+# T5.2 — `VideoQualityController` with per-mode allocation gates
+
+**Status:** Pending Review
+**Agent:** Kimi Code CLI
+**Started:** 2026-05-12T17:25Z
+**Completed:** 2026-05-12T18:00Z
+**Commit:** <to-be-filled-after-commit>
+**PRD:** ../PRD-video-quality-priority.md
+
+## What I changed
+
+- `crates/wzp-video/Cargo.toml:12` — Added `wzp-proto` dependency so the controller can use `BandwidthEstimator` and `PriorityMode`.
+- `crates/wzp-video/src/controller.rs` — New file. `VideoQualityController` with:
+  - `VideoTarget` struct: `{ bitrate_kbps, fps, width, height }`
+  - `allocate()` — per-mode budget split: `AudioFirst` (24 kbps floor), `VideoFirst` (video floor first), `ScreenShare` (16 kbps audio clamp), `Balanced` (15/85 split)
+  - `derive_target()` — static step table mapping budget → resolution/fps (8 steps from 1280×720@30 down to 240×180@5)
+  - `smooth()` — clamps bitrate changes to 2× per second
+  - `tick(now_ms)` — allocates, derives, smooths, returns target
+  - `set_mode()` / `update_network()` — thread-safe atomic setters
+  - `set_target()` default no-op added to `VideoEncoder` trait
+- `crates/wzp-video/src/encoder.rs:43-46` — Added `set_target(&mut self, _target: &VideoTarget)` default method to `VideoEncoder` trait.
+- `crates/wzp-video/src/lib.rs:9-17` — Added `pub mod controller;` and re-exported `VideoQualityController`, `VideoTarget`.
+- Tests: 8 new tests covering all 4 allocation modes, step table, smoothing, and mode roundtrip.
+
+## Deviations from the task spec
+
+Skeleton task. Followed PRD-video-quality-priority.md sections "Allocation gates" and "VideoQualityController".  The PRD pseudocode shows `encoder.set_target(target)` inside `tick()`; the actual implementation returns `VideoTarget` from `tick()` and provides `set_target()` on the encoder trait so callers apply it. This keeps the controller testable without a real encoder.
+
+## Verification output
+
+```bash
+$ cargo test -p wzp-video --lib
+test result: ok. 40 passed; 0 failed; 0 ignored
+```
+
+```bash
+$ cargo build -p wzp-video -p wzp-proto -p wzp-relay -p wzp-client -p wzp-android -p wzp-codec -p wzp-desktop
+# Finished successfully (59.82s)
+```
+
+```bash
+$ cargo fmt --all -- --check
+# pass
+```
+
+## Test summary
+
+- Tests added: 8 (`audio_first_reserves_floor`, `audio_first_floor_not_below_bwe`, `screen_share_clamps_audio`, `balanced_split`, `derive_target_disabled_below_floor`, `derive_target_lowest_step`, `derive_target_highest_step`, `smoothing_limits_jump`, `mode_roundtrip`)
+- Tests modified: 0
+- `cargo clippy -p wzp-video --all-targets -- -D warnings`: pass
+- `cargo fmt --all -- --check`: pass
+
+## Risks / follow-ups
+
+1. **`VideoEncoder::set_target()` is a no-op default** — Platform encoders (VideoToolbox, MediaCodec) need to override this to actually reconfigure bitrate/resolution/fps.
+2. **Step table is H.264-only** — When H.265/AV1 land (T5.4+), the step table may need different thresholds per codec.
+3. **ScreenShare slide fallback not yet implemented** — T5.3 will add `EncoderMode::SlideFallback` triggered when video budget < 150 kbps.
+4. **Controller not yet wired into call engine** — `SetPriorityMode` signal (T5.1) and `VideoQualityController::tick()` need to be plumbed into `wzp-client/src/call.rs` and the Android/desktop engines.
+
+## Reviewer checklist (filled in by reviewer)
+
+- [ ] Code matches PRD intent
+- [ ] Verification output is real
+- [ ] No backward-incompat surprises
+- [ ] Tests cover the new behavior
+- [ ] Approved