research(R4) + adr-105: federated CSI training with MERIDIAN+Krum+mincut (#716)

Federated learning is the unique design that satisfies the three
constraints from this loop's earlier work:
- R14 (data stays on-device)
- R3  (no cross-installation linkage)
- R7  (multi-node adversarial defence)

ADR-105 proposes MERIDIAN-FedAvg with Byzantine-robust (Krum)
aggregation and R7-style Stoer-Wagner mincut on inter-node update
similarity. Per-round bandwidth at typical 4-seed installation:
~12 MB; weekly cadence x monthly = 50-180 MB/month (0.06% of home
broadband cap).

Composes with every prior thread:
- R3 MERIDIAN centroid subtraction is mandatory pre-aggregation
- R7 mincut extended from multi-link CSI to multi-node updates
- R12/R13 negative results informed the byzantine + SNR-threshold choices
- R14 privacy framework baseline is now operational
- ADR-024/027/029/100/103/104 all bridged in the ADR

Implementation plan: ~500 LOC for ruview-fed crate. Krum aggregator
(80 LOC), LoRA+int8 delta codec (120 LOC, reuse ruvllm-microlora),
MERIDIAN centroid hook (50 LOC, extend AgentDB), inter-seed mincut
(100 LOC, reuse ruvector-mincut), CLI surface (80 LOC).

Explicitly deferred:
- Cross-installation federation (legal + DP work needed, future ADR)
- Member inference defence (ADR-106 with formal DP-SGD)
- Per-cog training-loop details (each cog implements local_train)
- Compute scheduling (cognitum fleet manager territory)

Tick chose the 'one ADR' unit from the cron prompt rather than another
numpy demo -- federation is fundamentally a protocol-design problem,
not a numerical-experiment problem.

Coordination: ticks/tick-13.md, no PROGRESS.md edit.

docs/research/sota-2026-05-22/ticks/tick-13.md

@@ -0,0 +1,51 @@
+# Tick 13 — 2026-05-22 06:13 UTC
+
+**Thread:** R4 (federated learning)
+**Verdict:** ADR-105 drafted. Federated CSI training is the unique design that satisfies R14 (data-stays-on-device) + R3 (no cross-installation linkage) + R7 (multi-node adversarial defence) simultaneously.
+
+## What shipped
+
+- `docs/adr/ADR-105-federated-csi-training.md` — full ADR draft covering protocol, threat model, bandwidth analysis, alternatives, implementation plan.
+
+This tick chose the "one ADR" unit option from the cron prompt rather than another numpy demo — federation is fundamentally a protocol-design problem, not a numerical-experiment problem. Architectural decisions are the right unit when the question is "what's the right shape of the thing" not "what number does it give".
+
+## Headline protocol
+
+**MERIDIAN-FedAvg with Byzantine-robust (Krum) aggregation + R7 mincut update-level consistency.**
+
+Per-round bandwidth (4-seed installation):
+- Coordinator → nodes (multicast): 8 MB checkpoint
+- Each node → coordinator: 1 MB delta (LoRA-rank-8 + int8 quantisation)
+- Total per round: ~12 MB
+- Weekly × monthly = ~50-180 MB/month/installation (0.06% of typical broadband cap)
+
+## Why ADR-105 not another numpy demo
+
+R3 (last tick) said: "re-ID is the primitive that makes empathic appliances ship". R4 says: "federation is the protocol that makes re-ID training privacy-compliant." Together they trace the full pipeline from physics (R6) → embeddings (R3) → personalised features (R14) → trained how (R4) → defended how (R7).
+
+The protocol is the deliverable. ADR-105 specifies it; ruview-fed crate implementation (~500 LOC) is the next-quarter work.
+
+## Composes with every prior thread
+
+- **R3** — MERIDIAN env centroid subtraction is **mandatory** pre-aggregation step.
+- **R7** — Stoer-Wagner mincut extended from multi-link CSI to multi-node update consistency.
+- **R12 / R13** — two negative results informed the byzantine-robust + SNR-threshold-on-updates choices.
+- **R14** — privacy framework's "data stays on-device" baseline is now operational.
+- **ADR-024 (AETHER), ADR-027 (MERIDIAN), ADR-029 (multistatic), ADR-100 (cog packaging), ADR-103 (cog-person-count), ADR-104 (MCP+CLI)** — all referenced in the ADR's "bridge to existing ADRs" section.
+
+## Honest scope landed
+
+- Cross-installation federation explicitly **deferred** to a future ADR (legal + DP work needed)
+- Member inference defence → ADR-106 with formal DP-SGD
+- The 500 LOC + 2-week-effort estimates assume AgentDB / microlora / mincut crates are stable
+- Krum byzantine bound: f < (K-2)/2 — practical f ≤ 4 for typical RuView installs
+
+## Coordination
+
+`ticks/tick-13.md`. No PROGRESS.md edit. Branch `research/sota-r4-federated-adr105`.
+
+## Remaining threads
+
+R15 (RF biometric across rooms) — now largely subsumed by R3 + ADR-105 cross-installation deferral. Could write a short "scoping note" for R15 in next tick to close the loop, or pick up the deferred items: physics-informed env_sig prediction (next R3 follow-up), or ADR-106 (DP-SGD on local training).
+
+~5.7h to cron stop. 13 threads landed (2 negative results, 1 ADR, 10 research notes with demos).