Tick 25 — 2026-05-22 09:01 UTC

Thread: R6.2.4 (3D chest-centric N-anchor multistatic — composes R6.2.2.1 + R6.2.3) Verdict: R6.2.2.1's prediction of "80%+ at N=5 in 3D chest-centric" partially validated: N=5 = 76.8%, N=6 = 81.6%. Knee shifts one anchor higher than predicted. Plus a counter-finding: no ceiling anchors selected for chest-centric zones.

What shipped

• examples/research-sota/r6_2_4_3d_chest_multistatic.py
• examples/research-sota/r6_2_4_3d_chest_results.json
• docs/research/sota-2026-05-22/R6_2_4-3d-chest-multistatic.md

4-way comparison at N=5

Configuration	Coverage
R6.2.2 (2D body)	96.8%
R6.2.3 (2D chest)	82.4%
R6.2.2.1 (3D body)	49.4%
R6.2.4 (3D chest)	76.8%

3D chest recovers 27 pp of the 47 pp gap that R6.2.2.1 surfaced. Most of the architectural fix works.

Counter-finding: ceiling anchors not selected

At no N does greedy pick a ceiling (z=2.4 m) anchor for chest-centric zones. Heights are 100% low (0.8 m) + mid (1.5 m).

Why: chest zones at z=0.3-1.5 don't benefit from ceiling anchors whose envelope sits at z≈2.4. R6.2.1's "include ceiling" rec was correct for full-body coverage, not chest-centric.

Sharpened recommendation: anchor heights should match target-zone heights.

Target	Best anchor heights
Bed-only (z=0.3-0.6)	Low only
Chair / sitting (z=0.5-1.0)	Low + mid
Standing chest (z=1.2-1.5)	Mid only
Mixed chest (z=0.3-1.5)	Low + mid (NO ceiling)
Full body (z=0.3-1.7)	Low + mid + high (per R6.2.1)

Final ADR-029 anchor-count table (4-axis)

Configuration	N	Coverage
2D body-centric	5	97%
2D chest-centric	5	82%
3D body-centric	7-8	65%+
3D chest-centric	6	82%

For vital-signs cogs in real 3D deployments: N=6 + chest-centric zones + low/mid anchor heights.

R6 family substantively complete

8 ticks in the R6 family:

• R6 (forward model)
• R6.1 (multi-scatterer)
• R6.2 (2D placement)
• R6.2.1 (3D placement)
• R6.2.2 (2D N-anchor)
• R6.2.2.1 (3D N-anchor)
• R6.2.3 (chest-centric)
• R6.2.4 (3D + chest) ← this tick

Covered: physics, body model, 2D/3D placement, N-anchor, chest-vs-body zones. Remaining items (pose-trajectory-aware, multi-subject union) need empirical AETHER + R3 data, out of scope for synthetic-data ticks.

Second self-corrective tick

R6.2.2.1 predicted 80%; actual is 76.8%. Self-correction is documented (prediction was 3.2 pp optimistic, knee shifts to N=6). This is the integrity pattern the loop has been producing — explicit predictions, explicit corrections.

Composes with prior threads

• R6.2.1 / R6.2.2 / R6.2.2.1: same physics, different zones
• R6.2.3 motivated this tick
• R7 / ADR-029 / ADR-105: N=6 still satisfies byzantine + Krum requirements
• R14 V1/V2/V3: chest-mode + N=6 is the empathic-appliance deployment recipe

Honest scope

• Greedy + 4 restarts; N=5 likely 2-4 pp shy of true global
• 0.1 m 3D grid; single geometry
• Three chest zones (real deployments would have one to many per occupant)
• R6.2.1's ceiling rec was for full-body, not invalidated — just refined

Coordination

ticks/tick-25.md. No PROGRESS.md edit. Branch research/sota-r6.2.4-3d-chest-multistatic.

Remaining work

• R6.2.5: multi-subject occupancy union (needs AETHER + R3 data)
• R12.1: pose-PABS closed loop
• R3.2: embedding-level physics-informed env
• ADR-108: Kyber substitution

~3.0h to cron stop. 25 ticks landed. Loop covered 13 research threads + 3 ADRs + 10 deferred follow-ups + 8-tick R6 family + 3 negative-result categories + 2 self-corrections.