Tick 23 — 2026-05-22 08:33 UTC

Thread: R6.2.3 (chest-centric placement) Verdict: Chest-centric targeting gains +26.9 pp coverage vs body-centric for vital-signs cogs. R6.2's CLI needs a --target-mode=chest flag.

What shipped

• examples/research-sota/r6_2_3_chest_centric.py — pure-numpy chest-vs-body placement benchmark.
• examples/research-sota/r6_2_3_chest_centric_results.json — full benchmark.
• docs/research/sota-2026-05-22/R6_2_3-chest-centric-placement.md — research note.

Headline

5×5 m bedroom, same antenna candidate grid, two zone definitions:

Configuration	Coverage	Best placement
Body-centric (R6.2 default)	49.3%	(4.25, 0) ↔ (0, 3.25), 5.35 m
Chest-centric (R6.2.3 new)	82.4%	(2.0, 0) ↔ (4.5, 5), 5.59 m

Cross-eval:

• Body-optimal applied to chest zones: 55.5%
• Chest-targeting gain on chest zones: +26.9 pp
• Chest-optimal applied to body zones: 40.3% (-9.0 pp)

The two strategies are not equivalent. Different cogs want different placements.

Per-cog deployment recommendation surfaced

--target-mode	Zones	Best cog use
body (default)	Full body footprint	cog-person-count, cog-pose-estimation, cog-presence
chest (new)	40×40 cm chest patches	cog-vital-signs, cog-breathing, cog-heart-rate
extremity (future)	Hand/foot zones	Gesture detection (not in scope)

Same engine, different zones. ~20 LOC change to R6.2 CLI.

Why placements differ

• Body-centric threads across the room to compromise across 3 m² bed + chair + desk by gross-area centroids.
• Chest-centric threads more efficiently through the 3 small chest patches because targets fit inside the Fresnel envelope.

When target ≈ envelope width, the envelope can cover it entirely. When target >> envelope, placement is forced to compromise.

R14 vertical-specific recommendation

• V1 stress-responsive lighting: needs breathing rate → chest mode
• V2 adaptive HVAC: presence + breathing → mixed (placement for chest, additional anchors for presence)
• V3 attention-respecting conversational: shallow-breathing recovery → chest mode

R6.2.3 surfaces a per-cog config that empathic-appliance products need at install time.

Composes with prior threads

• R6.1 motivated this tick: chest = 27.6% of signal, limbs are confound
• R6.2 / R6.2.1 / R6.2.2 — orthogonal: chest-centric works in 2D, 3D, N-anchor
• R14 V1/V3 — should use chest mode
• R12 PABS — chest-centric placement improves body-position-detection scenarios

Honest scope

• Chest positions approximated (humans don't sit/lie at fixed coords)
• 2D still; 3D chest-centric = R6.2.3.1 follow-up (~+3-5 pp expected)
• Single subject; multi-subject = union of chest envelopes
• Per-cog zone schema is deployment-time, not research-time

Coordination

ticks/tick-23.md. No PROGRESS.md edit. Branch research/sota-r6.2.3-chest-centric.

Remaining work

• R6.2.3.1: 3D chest-centric (R6.2.1 + R6.2.3 compose)
• R6.2.4: pose-trajectory-aware chest zones (needs AETHER + ADR-105 federation)
• R12.1: pose-PABS closed loop
• R3.2: embedding-level physics-informed env (from R3.1's corrected sketch)
• ADR-108: Kyber substitution

~3.4h to cron stop. 23 ticks landed. Loop now has 13 research threads + 3 ADRs + 8 deferred follow-ups closed.