Tick 19 — 2026-05-22 07:44 UTC

Thread: R12 PABS implementation Verdict: R12 NEGATIVE → POSITIVE. PABS detects unexpected occupants at 1,161× natural drift floor vs R12 naive SVD's 11× — a ~100× lift purely from using physics-grounded prediction.

What shipped

• examples/research-sota/r12_pabs_implementation.py — pure-numpy PABS over R6.1's multi-scatterer forward operator.
• examples/research-sota/r12_pabs_results.json — full 6-scenario benchmark.
• docs/research/sota-2026-05-22/R12-pabs-implementation.md — research note documenting the NEGATIVE → POSITIVE conversion.

Headline benchmark

Scenario	PABS / drift	SVD (R12 baseline) / drift
Empty room (subject missing)	7,362×	65×
Subject as expected (sanity check)	0×	0×
+1 new furniture	84×	11×
+1 unexpected human	1,161×	11×
Subject moved 10 cm	21,966×	90×
Natural drift floor (5% wall)	1×	1×

Why this is the meta-positive result

Two negative results in this loop (R12, R13). R12 has now been revisited and turned positive by using a tool (R6.1's multi-scatterer forward operator) that didn't exist when R12 was first run. This is the meta-lesson:

A research loop that catalogues NEGATIVE results creates a backlog of revisitable work that pays off when later tools become available. R12 → R12 PABS is a worked example.

R13 cannot be similarly revisited — its 5 dB shortfall is a hard physics floor, not a missing model.

The subject-moved-10cm caveat

Scenario F gives PABS=22,000×, which looks like a bug but is correct behaviour. PABS detects any structural mismatch between expected and observed. Real production PABS needs a pose-aware forward model that updates the expected scene from pose_tracker.rs in real-time. The actual structure-detection signal is PABS-after-pose-update.

This is ~50-100 LOC of Rust glue. Catalogued as R12.1 follow-up.

Composes with everything

• R6.1 unblocked this implementation
• R7 gets precise per-link consistency definition (residual norm small on all links → no structure; spike on one → either local structure OR compromised link; mincut disambiguates)
• R11 (maritime) enables container-tamper / hatch-seal applications
• R12 NEGATIVE → POSITIVE
• R14 (V0 security feature) intruder detection without biometric storage
• ADR-029 needs to reference PABS as the structure-detection primitive
• R10 (foliage) PABS-vs-forest works if canopy modelled or learned

Honest scope

• Pose-PABS closed loop not yet built (every subject move = false alarm)
• Synthetic data only; real-world drift floor needs measurement
• Population-prior body; per-subject body would tighten residual
• Single time-frame (real pipeline needs temporal averaging)

Coordination

ticks/tick-19.md. No PROGRESS.md edit. Branch research/sota-r12-pabs-implementation.

Remaining work

• R12.1: pose-PABS closed loop
• R12.2: localised residual decomposition (where is the structural change)
• R12.3: real-world validation on bench ESP32 captures
• R3 follow-up: physics-informed env_sig prediction
• R6.2.1: 3D ceiling/floor placement
• R6.2.3: chest-centric / pose-trajectory zones
• ADR-107: cross-installation federation w/ secure aggregation

~4.3h to cron stop. 19 ticks landed. 1 NEGATIVE result revisited and turned POSITIVE.