docs(adr): ADR-085 — RaBitQ pipeline expansion (proposed) (#433)

Extends ADR-084's RaBitQ-as-similarity-sensor pattern from five sites
to twelve, adding seven additional pipeline locations the user
identified during ADR-084 implementation:

- Per-room adaptive classifier short-circuit (Mahalanobis prefilter)
- Recording-search REST endpoint (GET /api/v1/recordings/similar)
- WiFi BSSID fingerprinting (channel-hop scheduler input)
- mmWave (LD2410 / MR60BHA2) signature wake-gate
- Witness bundle drift detection (CI ratchet)
- Agent / swarm memory routing (ADR-066 swarm bridge)
- Log / event-pattern anomaly detection (cluster Pi)

Each site has a 2-3 sentence decision (what gets sketched, what
triggers the comparison, what the refinement does on miss) and a
witness-hash artifact (what the system stores in place of the raw
embedding/event/signal).

Implementation plan ordered cheapest-first / least-risky-first.
Acceptance criteria align with ADR-084 (8x-30x compare cost,
≥90% top-K coverage, <1pp accuracy regression) where applicable;
non-vector sites (witness bundle, BSSID time-series, event log)
have site-specific criteria.

Three open questions explicitly flagged:
1. Mahalanobis-after-binary-sketch is novel — no published primary
   source found, marked conjecture, decision deferred to bench
2. Canonical "non-vector → sketchable" encoding is unsolved
3. MERIDIAN (ADR-027) cross-environment domain interaction needs
   site-by-site analysis before bank rebuild semantics are committed

Status: Proposed. SOTA review by goal-planner agent.

docs/adr/ADR-085-rabitq-pipeline-expansion.md

@@ -0,0 +1,452 @@
+# ADR-085: RaBitQ Similarity Sensor — Pipeline Expansion (Seven Additional Sites)
+
+| Field          | Value                                                                                                                                          |
+|----------------|------------------------------------------------------------------------------------------------------------------------------------------------|
+| **Status**     | Proposed                                                                                                                                       |
+| **Date**       | 2026-04-25                                                                                                                                     |
+| **Authors**    | ruv                                                                                                                                            |
+| **Refines**    | ADR-084 (RaBitQ similarity sensor, five-site baseline)                                                                                         |
+| **Touches**    | ADR-027 (cross-environment generalization), ADR-028 (capability audit / witness bundle), ADR-066 (swarm-bridge to coordinator), ADR-073 (multifrequency mesh scan), ADR-076 (CSI spectrogram embeddings), ADR-081 (5-layer firmware kernel), ADR-082 (confirmed-track filter), ADR-083 (per-cluster Pi compute hop) |
+| **Companion**  | `v2/crates/wifi-densepose-ruvector/src/sketch.rs` (ADR-084 Pass 1 — `Sketch`, `SketchBank`, `SketchError`; on branch `feat/adr-084-pass-1-sketch-module`, commits `6fd5b7d` + `1df9d5f7d`) |
+
+## Context
+
+ADR-084 committed RuView to **RaBitQ-style binary sketches as a cheap
+similarity sensor** (Gao & Long, SIGMOD 2024 — arxiv 2405.12497) at
+five pipeline sites: AETHER re-ID pre-filter, cluster-Pi novelty,
+mincut subcarrier maintenance, mesh-exchange compression, and the
+privacy-preserving event log. Pass 1 of that work landed the
+`wifi-densepose-ruvector::sketch` module and benched at **43–51×
+compare speedup at d=512** and **7.5× top-K speedup at k=8 over 1024
+sketches** — comfortably above the ADR-084 acceptance threshold of
+8×. The sketch primitive is no longer an open question; the question
+is where else in the pipeline the same sensor pattern earns its keep.
+
+Seven additional sites have been identified, all outside the ADR-084
+five but matching the same shape — code that asks "is this familiar?"
+against a stored set, today by way of a full float compare or model
+invocation. The unifying rule articulated alongside ADR-084 — *sketch
+first, refine on miss, store the witness hash instead of the raw
+embedding* — applies to all seven.
+
+This ADR formalizes those seven sites in one document rather than
+seven small ADRs because (a) they share one primitive and one
+acceptance shape, so evaluating in isolation hides the pattern;
+(b) most involve modest code surgery (< 200 LOC at the call site)
+and an ADR-per-site would inflate the ledger without buying
+decision-resolution; (c) the few sites that *do* raise novel
+questions (Mahalanobis pre-filtering, REST similarity API shape,
+witness-hash format for non-vector data) are flagged under Open
+Questions and may spin out as follow-ups if their answers prove
+load-bearing. ADR-084 owns the primitive; ADR-085 owns the
+*deployment surface*.
+
+## Decision
+
+Apply the ADR-084 sketch sensor pattern at seven additional sites,
+listed in the order they will be implemented (cheapest-first /
+lowest-risk-first). Each entry states (a) **what is sketched**,
+(b) **what triggers the comparison**, (c) **what the refinement step
+on a miss is**, and (d) **what artifact stands in for the raw
+embedding** — i.e., the witness hash.
+
+### Site 1 — Per-room adaptive classifier short-circuit
+
+**Crate:** `wifi-densepose-sensing-server` —
+`src/adaptive_classifier.rs::classify` (per-class centroids and spread,
+Mahalanobis-like distance per frame).
+
+- **Sketched:** Each per-class centroid `µ_k` (already a fixed-dim
+  feature vector). Sketches live in a `SketchBank` keyed by class id,
+  rebuilt whenever a class is re-trained.
+- **Trigger:** Every classification call, before the float Mahalanobis
+  distance loop runs.
+- **Refinement on miss / first cut:** Hamming top-K (K = 3) selects
+  candidate classes; full Mahalanobis runs only on those K. If the
+  hamming top-1 disagrees with the eventual Mahalanobis winner, log
+  the disagreement and fall back to full evaluation against all
+  classes for that frame.
+- **Witness hash:** `sha256(centroid_bytes || spread_bytes ||
+  sketch_version)` per class, recorded once at classifier-train time
+  and stored alongside the sketch.
+
+The sketch only narrows; Mahalanobis still decides on the K
+candidates, preserving the original distance-to-class semantics.
+Substituting Mahalanobis for the standard RaBitQ exact-distance
+re-rank step (Gao & Long 2024) is, to our knowledge, novel — Open Q1.
+
+### Site 2 — Recording-search REST endpoint
+
+**Crate:** `wifi-densepose-sensing-server` —
+`src/recording.rs` plus a new HTTP handler in `src/main.rs`.
+
+- **Sketched:** Each recording's pooled CSI/embedding signature (mean
+  AETHER embedding over the recording, or mean spectrogram embedding
+  per ADR-076). One sketch per recording, stored next to the recording
+  metadata.
+- **Trigger:** `GET /api/v1/recordings/similar?to=<id>&k=N` request.
+- **Refinement on miss:** Hamming top-K returns a candidate list of
+  recording ids. Full embedding refinement is **opt-in** via a
+  `&refine=true` query param that loads the candidate recordings'
+  full embeddings (if stored) and re-ranks. Default behavior is
+  sketch-only — the endpoint trades exact ranking for the ability to
+  ship without storing full embeddings server-side.
+- **Witness hash:** `sha256(sketch_bytes || recording_id ||
+  sketch_version)` returned in the response payload as the result row
+  identifier. The raw embedding is **not retained** by default; the
+  hash is the artifact a client can use to assert which sketch
+  produced the match.
+
+Delivers "find recordings that look like this one" without
+long-term embedding storage. The shape is closer to SimHash dedup
+APIs than to Qdrant's `/collections/{name}/points/search` (the
+closest Rust-native vector-DB endpoint, which returns full vectors)
+— deliberate; see Open Q4.
+
+### Site 3 — WiFi BSSID fingerprinting (channel-hop scheduler input)
+
+**Crate:** `wifi-densepose-wifiscan` —
+new `bssid_sketch` module beside the existing scan/result types.
+
+- **Sketched:** A short per-BSSID time-series feature vector — recent
+  RSSI, SNR, channel, beacon interval, capability flags — pooled over
+  a rolling window (e.g., last 60 s). One sketch per (BSSID, window).
+- **Trigger:** Each scan tick, after the multi-BSSID scan completes.
+  The current window's sketch is compared against the prior window's
+  bank.
+- **Refinement on miss:** A sketch whose nearest neighbor's hamming
+  distance exceeds a threshold flags the BSSID as **novel** (newly
+  appeared, or known-AP-changed-beyond-recognition). The hop scheduler
+  (ADR-073) reads novelty as a hint to give the affected channel
+  more dwell time on the next rotation.
+- **Witness hash:** `sha256(bssid || pooled_features || sketch_version
+  || window_end_unix)` stored in the per-AP novelty log; raw
+  per-BSSID time series is dropped after the sketch is taken.
+
+Anomaly detection over a heterogeneous low-dim vector; acceptance
+is **false-positive rate on stable deployments**, not top-K
+coverage. IEEE 802.11bf-2025 (published March 2025) standardizes
+sensing measurement frames but not BSSID-novelty heuristics, so
+this site does not duplicate the standard's scope.
+
+### Site 4 — mmWave radar signature memory
+
+**Crate:** `wifi-densepose-vitals` —
+`src/preprocessor.rs` and `src/anomaly.rs` (LD2410 / MR60BHA2 input
+path).
+
+- **Sketched:** A per-frame radar signature vector — range bins,
+  Doppler bins, peak frequencies — sketched at the same cadence as
+  the radar input (~10 Hz).
+- **Trigger:** Every incoming radar frame, before the heavy vital
+  signs DSP runs. The current sketch is compared against a small
+  per-room "have we seen this kind of frame before" bank.
+- **Refinement on miss:** A sketch within hamming distance of a known
+  signature short-circuits to "no new event"; vital signs DSP stays
+  asleep. A sketch beyond threshold wakes the full breathing/heart
+  pipeline (`vitals::breathing`, `vitals::heartrate`) for one or more
+  frames, then re-sleeps once the bank update settles.
+- **Witness hash:** `sha256(signature_bytes || sensor_kind ||
+  sketch_version)` stored in the vitals event log; the raw radar
+  frame is not retained beyond the rolling preprocessor buffer.
+
+Energy is the headline: vital signs DSP (band-pass + phase-fusion +
+heart/breath FFT) is the most expensive cluster-Pi operation per
+minute of quiet-room time. Published FMCW pipelines treat the DSP
+stage as always-on after presence; **no primary source** found for
+"binary-sketch wake-gate over a per-room radar signature bank" —
+this is a direct extension of ADR-084's novelty sensor.
+
+### Site 5 — Witness bundle similarity (ADR-028 release-CI signal)
+
+**Crate:** Out-of-tree — addition to `scripts/generate-witness-bundle.sh`
+plus a new `scripts/witness_drift_check.py`.
+
+- **Sketched:** Each release's witness bundle "fingerprint" — a fixed
+  vector built from per-component SHA-256 prefixes plus numeric
+  attestation values (test count, proof hash byte-segments,
+  per-firmware sizes). One sketch per release.
+- **Trigger:** Run during the CI release job, after the witness
+  bundle is generated and before publication.
+- **Refinement on miss:** A sketch whose hamming distance to the prior
+  release exceeds threshold flags the release as **drifted** and
+  surfaces the changed components in the CI summary. The release is
+  not blocked; the signal is a ratchet that says "these components
+  changed by more than the recent baseline, take a second look."
+- **Witness hash:** `sha256(sketch_bytes || release_tag ||
+  sketch_version)` published alongside the witness bundle as
+  `WITNESS-LOG-<sha>.sketch`. The full bundle is the existing artifact;
+  the sketch hash is a 32-byte add-on.
+
+Conservative use of the sensor — drift detection over a *very*
+small candidate set (last 5–10 releases). Existing CI drift prior
+art is autoencoder/SHAP-based commit-anomaly detection plus
+PKI-signed artifact integrity; **no primary source** for
+"binary-sketch over release-bundle fingerprint" as a CI signal.
+Acceptance: "useful ratchet without false-firing on every
+dependency bump." If no, the sketch step drops from the release
+script — most readily revertible of the seven.
+
+### Site 6 — Agent / swarm memory routing
+
+**Crate:** `wifi-densepose-sensing-server` —
+`src/multistatic_bridge.rs` (ADR-066 swarm-bridge channel) and the
+peer Cognitum Seed registration metadata.
+
+- **Sketched:** Each Cognitum Seed's accumulated **historical bank**
+  signature — a pooled mean of the sketches it has stored over a
+  rolling horizon. One sketch per peer Seed; refreshed at peer
+  heartbeat cadence.
+- **Trigger:** A sensor node escalates an event to the swarm. Before
+  broadcasting to all peer Seeds, the cluster Pi computes the event's
+  sketch and routes it to the **closest peer** by hamming distance.
+- **Refinement on miss:** No nearby peer (all hammings above threshold)
+  → broadcast to all. Nearby peer hits → unicast to that Seed first;
+  only escalate to broadcast if the routed Seed cannot resolve.
+- **Witness hash:** `sha256(event_sketch || origin_seed_id ||
+  routed_seed_id || sketch_version || event_unix)` recorded in the
+  swarm-bridge audit log. The full event sketch is exchanged; the
+  hash is the routing-decision attestation.
+
+A 12-Seed swarm broadcasting every event is O(n) message storm per
+event; sketch-routing turns the common case into O(1) with O(n)
+fallback. Closest published comparator: **MasRouter** (ACL 2025),
+which routes LLM queries via a learned DeBERTa router; ADR-085's
+variant is structurally similar but uses unlearned hamming compare
+against each peer's pooled bank — cheaper, and resilient to peer
+churn.
+
+### Site 7 — Log / event-stream pattern detection
+
+**Crate:** `wifi-densepose-sensing-server` —
+new `src/event_anomaly.rs` module reading the cluster Pi's
+existing event stream.
+
+- **Sketched:** A pooled feature vector over the recent-events window
+  (last hour by default) — counts per event type, mean inter-event
+  interval, sources distribution. One sketch per cluster, refreshed
+  every 5 minutes.
+- **Trigger:** Every refresh tick. The current-hour sketch is compared
+  against the historical bank (last 24 hours of hourly sketches).
+- **Refinement on miss:** Hamming distance above threshold flags the
+  hour as **anomalous behavior**; the cluster Pi raises a single
+  cluster-level alert with a pointer to the witness hash, **not** to
+  the raw events. No raw events leave the Pi as part of the alert
+  payload.
+- **Witness hash:** `sha256(hourly_sketch || cluster_id || hour_unix
+  || sketch_version)` recorded as the alert body. Raw events stay on
+  the cluster Pi behind the existing privacy boundary.
+
+The most genuinely "anomaly detection" of the seven, and most
+exposed to the non-vector witness-hash open question (event
+features are mixed counts and rates needing normalization before
+sketching). Closest published comparator: **LogAI** (Salesforce,
+Drain parser → counter vectors → unsupervised detection); ADR-085's
+variant sketches the counter vector, trading recall for constant
+memory and sub-ms compare on the cluster Pi.
+
+### Witness-hash discipline
+
+In every site above, the witness hash replaces the raw embedding /
+feature vector at the storage boundary — the same privacy posture
+ADR-084 introduced for the cluster-Pi event log, generalized across
+seven new contexts. The format is uniform:
+`sha256(sketch_bytes || stable_metadata || sketch_version)`. Where
+the input is not natively a dense vector (Sites 5 and 7), the
+encoding into a sketchable shape is itself a design choice — see
+Open Questions.
+
+## Consequences
+
+### Positive
+
+- **The "is this familiar?" pattern becomes a first-class deployment
+  primitive across REST APIs, scanning subsystems, mmWave gating,
+  CI, swarm routing, and event analytics.** Each site is a modest
+  win individually; together they remove the last excuses to keep
+  full embeddings on every storage and exchange path.
+- **Energy and bandwidth wins compound at the cluster boundary.**
+  Site 4 cuts vital signs DSP duty cycle; Site 6 cuts cross-cluster
+  broadcast load. Both are at the cluster Pi, where wattage matters.
+- **Privacy story strengthens.** Every site stores a witness hash,
+  not raw data. Sites 2 and 7 are explicitly designed to ship
+  without retaining the embeddings or event payloads they index.
+- **Reuses ADR-084 Pass 1 with no new dependency.** The
+  `wifi-densepose-ruvector::sketch` module already exposes
+  `Sketch`, `SketchBank`, `SketchError` at 43–51× compare speedup.
+- **Each site is independently testable and revertible.** The seven
+  passes share no data paths; failure at any one rolls back without
+  touching the others.
+
+### Negative / risks
+
+- **Mahalanobis distributional assumption (Site 1).** Pure 1-bit
+  sign quantization performs best on zero-centered, isotropic
+  embeddings; Mahalanobis explicitly encodes covariance structure
+  hamming distance is insensitive to. The sketch is used **only**
+  as a candidate-narrower; the Mahalanobis re-score preserves
+  semantics. But if hamming top-K systematically excludes the true
+  winner, the short-circuit is worse than no short-circuit. The
+  Validation acceptance test guards this; randomized rotation
+  pre-pass (RaBitQ-paper-style) may be needed — see Open Q1.
+- **REST endpoint shape (Site 2) is an API surface commitment.**
+  A `GET /api/v1/recordings/similar` with a sketch-only default
+  is a contract; clients expect approximate-recall behavior.
+  Documenting "sketch-only by default, `&refine=true` for full
+  re-ranking" is part of the acceptance bar.
+- **False-positive risk on Site 3 (BSSID novelty)** in dynamic
+  environments. Coffee-shop / co-working deployments see BSSIDs
+  rotate constantly; the signal must flag *unexpected* change,
+  not background churn — acceptance is framed accordingly.
+- **Witness-hash format for non-vector inputs (Sites 5 and 7).**
+  Witness bundles and event streams are not natively dense-vector
+  data; the encoding into sketchable form (numeric SHA-prefix
+  segments; normalized event-type histograms) is itself a design
+  choice future model changes can break. `sketch_version` bumps
+  invalidate banks everywhere, but only Sites 5 and 7 must
+  re-encode raw inputs.
+- **Operational surface area.** Seven banks each with their own
+  persistence, version-skew, and refresh story. The cluster Pi
+  gains non-trivial state. ADR-083's secure-boot / OTA story
+  holds, but state-rebuild cost on `sketch_version` bump is now
+  seven banks, not one.
+
+### Neutral
+
+- The five ADR-084 sites and the seven sites here are independent.
+  Acceptance or rollback at any one site does not propagate.
+- ADR-082 (confirmed-track filter) remains upstream of every sketch
+  call. ADR-081 (5-layer firmware kernel) is unchanged — every new
+  bank lives at the cluster Pi or higher.
+- ADR-027 (cross-environment generalization, MERIDIAN) interacts
+  cleanly: Site 1's per-class sketches are *per environment* by
+  construction, which is the same shape MERIDIAN already assumes.
+
+## Implementation
+
+Seven passes, ordered cheapest-first / lowest-risk-first. Each is
+independently shippable; each has a single-line acceptance test that
+must pass before the next pass starts.
+
+| # | Pass | Target crate | Acceptance test (one line) |
+|---|------|--------------|----------------------------|
+| 1 | **Witness bundle drift sketch** (Site 5) | `scripts/witness_drift_check.py` | CI run on the last 5 releases produces ≥ 1 drift flag on a known dependency-bump release and 0 flags on a known no-op release. |
+| 2 | **BSSID fingerprint novelty** (Site 3) | `wifi-densepose-wifiscan::bssid_sketch` | 24-hour soak in a stable office: novelty rate ≤ 5 events / hour; controlled new-AP injection: novelty fires within 2 scan cycles. |
+| 3 | **mmWave signature gate** (Site 4) | `wifi-densepose-vitals::preprocessor` | Vitals DSP CPU time / hour ≥ 4× lower in steady-state empty-room compared to no-gate baseline; missed-detection regression ≤ 1 pp on the existing breathing/heart fixtures. |
+| 4 | **Adaptive classifier short-circuit** (Site 1) | `wifi-densepose-sensing-server::adaptive_classifier` | Per-frame `classify` time reduced ≥ 2× at K = 3 candidates; classification accuracy regression ≤ 1 pp on the held-out test set. |
+| 5 | **Event-stream anomaly sketch** (Site 7) | `wifi-densepose-sensing-server::event_anomaly` | 7-day rolling deployment: ≤ 1 false anomaly / day; injection of a synthetic anomalous hour fires within one refresh tick. |
+| 6 | **Swarm memory routing** (Site 6) | `wifi-densepose-sensing-server::multistatic_bridge` | 12-Seed simulated swarm: per-event broadcast-message count drops ≥ 5× vs. unrouted baseline; routed-Seed-resolution rate ≥ 80%. |
+| 7 | **Recording-search REST endpoint** (Site 2) | `wifi-densepose-sensing-server::recording` + HTTP route | `GET /api/v1/recordings/similar` returns a top-K with ≥ 90% candidate-set agreement vs. full-embedding re-rank on the recorded dataset; response time < 50 ms at K = 10 over 1000 recordings. |
+
+ADR-084's general acceptance numbers — **8–30× compare cost
+reduction, ≥ 90% top-K coverage, < 1 pp accuracy regression** —
+apply unchanged to Sites 1 (classifier) and 2 (recording search),
+where the candidate set is large and top-K coverage is the right
+framing. Sites 3, 4, 5, 6 are gating / anomaly / routing problems
+measured against site-specific criteria above (false-positive rate,
+DSP duty cycle, broadcast count, drift-flag precision). Each pass
+adds three tests under `v2/crates/<target>/tests/`: property test
+(sketch ↔ float top-K where applicable), criterion bench
+(compare-cost ratio), end-to-end regression against recorded data.
+Benches reuse the ADR-084 Pass 1 harness.
+
+## Validation
+
+This ADR is **Proposed**. Acceptance requires **at least four of
+seven passes** to meet their per-row acceptance test. The four
+must-haves are: **Site 1** (per-frame cost; Mahalanobis assumption
+load-bearing), **Site 4** (cluster-Pi energy), **Site 6**
+(cross-cluster bandwidth), **Site 7** (privacy-preserving anomaly).
+Sites 2, 3, 5 are nice-to-haves and may ship or revert
+independently.
+
+Validation runs against:
+
+- existing workspace tests (must stay green at
+  `cargo test --workspace --no-default-features` on `v2/`);
+- a 7-day cluster-Pi soak at the lab fixture (3 sensor nodes + 1 Pi
+  per ADR-083) with recordings, mmWave, and BSSID scans active —
+  per-site logs graded against the Implementation table;
+- Python proof harness unchanged (`archive/v1/data/proof/verify.py`
+  must still print `VERDICT: PASS`);
+- regenerated witness bundle (ADR-028) including the Site 5 sketch.
+
+When the four must-haves pass and the soak holds, ADR moves
+**Proposed → Accepted** and README hardware/feature tables gain a
+sketch-bank row.
+
+## Open questions
+
+1. **Does Mahalanobis pre-filtering survive sign-quantization bias
+   on Site 1?** Pure 1-bit sketches discard the covariance
+   structure Mahalanobis uses. The pass-1 framing — sketch narrows,
+   Mahalanobis decides — preserves correctness in expectation, but
+   adversarial centroid geometries can let the hamming top-K
+   systematically exclude the true winner. **No primary source
+   found** for "binary-sketch + Mahalanobis-refine" as a published
+   pipeline; marked as conjecture, gated by the Site-1 acceptance
+   test. If it fails, the next experiment is the randomized
+   rotation pre-pass from Gao & Long (SIGMOD 2024, arxiv
+   2405.12497), which ADR-084 also flagged for AETHER /
+   spectrogram embeddings. A standalone follow-up ADR is the
+   likely outcome if rotation is needed.
+2. **Witness-hash format for non-vector data (Sites 5, 7).** The
+   release bundle (Site 5) and event stream (Site 7) are not
+   natively dense-vector inputs. The proposed encodings — numeric
+   SHA-256-prefix segments plus attestation values for Site 5;
+   normalized event-type histograms for Site 7 — are plausible
+   but unvalidated against drift in the underlying distributions.
+   A small follow-up ADR formalizing the "non-vector → sketchable"
+   canonical path is plausible if the two sites diverge.
+3. **Cross-environment domain generalization interaction
+   (ADR-027).** Per-class sketches in Site 1 and per-room banks at
+   Sites 4 and 7 are implicitly per-environment artifacts; ADR-027
+   (MERIDIAN) handles cross-environment generalization at the model
+   layer. When MERIDIAN's domain detector flags an environment
+   shift, do banks rebuild, swap, or merge? Default here is
+   **rebuild on shift**; a merge story may be cheaper and is open
+   for the eventual MERIDIAN-aware deployment.
+4. **REST API shape for Site 2.** The choice between
+   Qdrant/Pinecone/Weaviate-style endpoints (Qdrant being the
+   closest Rust-native comparator with HTTP `/points/search`) and
+   a thin sketch-only response is intentionally opinionated
+   toward the thin shape. **No Rust-idiom primary source** was
+   located for "sketch-only similarity search over recordings"
+   specifically; closest analog is SimHash-over-documents
+   deduplication, which lacks time-series-recording prior art.
+   If a clean Rust crate emerges owning this idiom, Site 2 may
+   delegate rather than ship bespoke.
+5. **BSSID novelty and 802.11bf-2025 interaction.** IEEE 802.11bf
+   was published in March 2025 and standardizes WLAN sensing
+   measurement frames; Site 3's novelty sketch operates above the
+   measurement layer (on RSSI/SNR/channel time-series) and should
+   not duplicate what 802.11bf eventually exposes natively. **No
+   primary source found** for "RSSI-fingerprint anomaly + 802.11bf"
+   — marked as conjecture; revisit when client/AP support arrives.
+
+## Related
+
+- **ADR-027** (Proposed) — MERIDIAN cross-environment generalization.
+  Per-environment sketch banks (Sites 1, 4, 7) need an explicit
+  swap/rebuild story under MERIDIAN-detected domain shifts.
+- **ADR-028** (Accepted) — ESP32 capability audit / witness bundle.
+  Site 5 adds a sketch ratchet to the existing release artifact.
+- **ADR-066** (Proposed) — Swarm bridge to coordinator. Site 6 routes
+  over the bridge channel ADR-066 defines.
+- **ADR-073** (Proposed) — Multifrequency mesh scan. Site 3's
+  BSSID novelty feeds the hop scheduler ADR-073 owns.
+- **ADR-076** (Proposed) — CSI spectrogram embeddings. Site 2's
+  recording-search sketch can pool over spectrogram embeddings
+  when present, or fall back to AETHER means.
+- **ADR-081** (Accepted) — 5-layer adaptive CSI mesh firmware kernel.
+  No firmware change; every new sketch bank is at the cluster Pi
+  or higher.
+- **ADR-082** (Accepted) — Pose tracker confirmed-track filter.
+  Upstream of every sketch call; unchanged.
+- **ADR-083** (Proposed) — Per-cluster Pi compute hop. The Pi is
+  the host for all seven new banks; ADR-083's deployment story is
+  the prerequisite.
+- **ADR-084** (Proposed) — RaBitQ similarity sensor (five-site
+  baseline). This ADR refines and extends; it does not duplicate
+  ADR-084's compare-cost / top-K / accuracy acceptance numbers
+  where unchanged.