Peter Woolery
62931e26ff
When a blob briefly drops below CV_MIN_BLOB_PX, its track is killed and respawns, causing the same person to generate multiple counts per visit (~50/min observed in field). Add a per-direction cooldown (default 5 frames ≈ 0.8s @ 5 fps) that drops subsequent entries (or exits) within the window of the last counted one. Entry and exit cooldowns are tracked independently. Fixed at compile time for now; exposing as a server-push tunable is deferred until the server-push-config branch lands. See docs/server-prompt-crossing- cooldown.md for the server-side coordination notes. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
79 lines
3.5 KiB
Markdown
79 lines
3.5 KiB
Markdown
# Server-Side Prompt — Crossing Cooldown Awareness
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> Give this to your server-side agent after the firmware commit that introduces
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> `CV_CROSSING_COOLDOWN_FRAMES` in `firmware/lib/cv/cv.h` has been flashed to devices.
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## Context
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The DoorCounter firmware now enforces a **per-direction crossing cooldown** in
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its CV pipeline. After a counted entry, subsequent entries within 5 frames
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(~1 second at 5 fps) are silently dropped on-device. Exits follow the same
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rule independently. This is a device-side fix for the known track-churn bug
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(single person producing 5+ counts per visit when their blob briefly drops
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below the minimum-blob-pixel threshold).
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Constants live in `firmware/lib/cv/cv.h`:
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```c++
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static const uint32_t CV_CROSSING_COOLDOWN_FRAMES = 5; // per-direction
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```
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Cooldown is **fixed at compile time**. It is **not** currently a server-
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pushable tuning parameter.
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## What the server should do
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1. **Expect lower per-hour entry/exit counts** from devices running this
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firmware compared to their historical baseline. This reflects suppression
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of false positives, not a device regression. Do not alert on the drop.
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2. **If you have a per-device tuning-config push mechanism** (the one planned
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in `.agent/plan.md` — server-push CV config via heartbeat response), add
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`cooldown_frames` to the sendable tuning set with:
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- Default: `5`
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- Valid range: `0..60` (0 disables cooldown; 60 ≈ 12s at 5 fps)
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- Semantics: per-direction, applied to both entries and exits
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- Persist alongside other CV tuning keys in NVS under a new key `cv_cool`.
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- Bump the `cfg_version` scheme accordingly.
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**Do not ship this server-side change yet** — the firmware change in this
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commit keeps the cooldown as a compile-time constant. A future firmware
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commit on `feature/server-push-config` will expose it as a runtime
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tunable and bump `cfg_version`. Coordinate the rollout: firmware first,
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then server.
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3. **Dashboard**: if you render device CV parameters in a per-device settings
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view, add a read-only row "Crossing cooldown (frames): 5" sourced from
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the firmware's compiled default. Mark it editable only once the firmware
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exposes it as a tunable.
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4. **Telemetry (optional, low priority)**: consider adding a field
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`suppressed_crossings_delta` to the heartbeat or camera-events payload
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so operators can see how often cooldown is kicking in. This would require
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a firmware change; flag it as future work only if churn continues.
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## What NOT to do
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- Do not attempt to push `cooldown_frames` via the existing config channel
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today — the firmware will ignore unknown fields, which is fine, but
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shipping server changes that assume the firmware-side plumbing exists
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will break the integration contract.
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- Do not "correct" the lower counts via server-side multiplication. The
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cooldown is the correct behavior; old counts were inflated by the churn
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bug.
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## Verification checklist
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- [ ] Historical counts chart annotated with "firmware v{N} deployed"
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marker on the rollout date.
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- [ ] Per-device tuning view renders cooldown row (read-only for now).
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- [ ] No alert fires on the per-device count drop post-rollout.
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## Reference
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- Firmware change: `firmware/lib/cv/cv.h` (`CV_CROSSING_COOLDOWN_FRAMES`),
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`firmware/lib/cv/cv.cpp` (suppression logic in `cv_process`).
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- Design spec: `docs/superpowers/specs/2026-04-13-door-counter-design.md`
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§ 3.1 "Counting logic".
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- Unit test: `firmware/test/test_cv/test_cv.cpp::test_cooldown_suppresses_rapid_re_entry`.
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