fix(homecore-api security): auth-gate GET /api/ (was unauthenticated) + recover WS subscription on broadcast lag (#1076)

* fix(homecore-api security): auth-gate GET /api/ (HC-API-AUTH-01, ADR-161)

`rest::api_root` took no headers and unconditionally returned
`200 {"message":"API running."}`, while every sibling REST route gates
on `BearerAuth::from_headers`. HA's `APIStatusView` inherits
`requires_auth = True`, so `/api/` must return 401 for a missing/wrong
bearer — HA clients use it as a token-validation probe, so a 200 told a
bad-token client its token was valid and let an unauthenticated party
confirm a live endpoint. LOW severity (static body, no data leak),
reported at true severity.

Fix: `api_root(headers, State)` validates the bearer like `get_config`.

Pinned by fails-on-old tests (200 -> assert 401):
- api_root_rejects_missing_bearer
- api_root_rejects_wrong_bearer
guarded by api_root_accepts_correct_bearer (still 200 with valid token).

Co-Authored-By: claude-flow <ruv@ruv.net>

* fix(homecore-api security): recover WS subscription on broadcast lag (HC-WS-LAG-01, ADR-161)

`subscribe_events`'s per-subscription task matched `Err(_) => break` on
both broadcast `recv()` arms. `RecvError::Lagged(n)` (a slow consumer
falling >EVENT_CHANNEL_CAPACITY=4,096 events behind) is recoverable —
the bus doc says "Lagged receivers must re-sync" and HA keeps the
subscription alive across a lag. The old code treated the first lag as
fatal, so after an event burst the client's stream went permanently
silent with no error frame — a self-inflicted event-delivery DoS under
load. LOW severity.

Fix: `Lagged(_) => continue` (skip dropped window, re-sync),
`Closed => break`, on both the system and domain arms.

Pinned by subscription_survives_broadcast_lag: subscribes, floods 6,000
filtered events past the 4,096 capacity to force a Lagged, then asserts
a subsequent subscribed event is still delivered (old code: 5s timeout).

Co-Authored-By: claude-flow <ruv@ruv.net>

* docs(homecore-api security): record HC-API-AUTH-01 + HC-WS-LAG-01 review (ADR-161)

CHANGELOG [Unreleased] Security entry + ADR-161 addendum documenting the
beyond-SOTA network-API review: two LOW bugs fixed (unauthenticated
GET /api/; WS subscription killed on broadcast lag) and the
auth/traversal/injection/info-leak/CORS dimensions confirmed clean with
evidence (no traversal surface — in-memory DashMap + EntityId allowlist;
HashSet token compare, not a byte-== timing oracle).

Co-Authored-By: claude-flow <ruv@ruv.net>

CHANGELOG.md

@@ -19,6 +19,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **ADR-260: RuField MFS — the open specification for camera-free multimodal field sensing.** A common event / tensor / calibration / privacy / provenance model that sits *above* WiFi CSI/CIR/BFLD, UWB, BLE Channel Sounding, mmWave radar, ultrasound, subsonic, infrared, and future quantum sensors (each modality emits a normalized `FieldEvent` → `FieldTensor` → `FusionGraph` → `PrivacyClass` → `ProvenanceReceipt`). Published as a **standalone repo** [`ruvnet/rufield`](https://github.com/ruvnet/rufield) and vendored here as the `vendor/rufield` submodule (the `vendor/rvcsi` pattern — not a `v2/` workspace member). The v0.1 reference stack is a self-contained 6-crate Rust workspace (`rufield-core`, `-provenance` [sha256 + ed25519], `-privacy` [P0–P5 guard], `-adapters` [deterministic `SyntheticSim` across wifi_csi/mmwave_radar/infrared_thermal], `-fusion` [graph + TOML weighted-Bayes rules → 7 room-state inferences], `-bench` [deterministic runner + the §31 acceptance test]). **60 tests / 0 failed, clippy-clean.** §27 acceptance criteria 1–8 and 10 PASS; the live dashboard (9) is deferred. **All benchmark metrics are SYNTHETIC** (scored against the simulator's own ground truth — presence/breathing/bed_exit/room_transition F1 = 1.000, nocturnal_scratch 0.923 reported honestly, p95 latency ~0.01 ms, provenance coverage 100%, 0 privacy violations) — they prove the pipeline recovers known truth, **not** field accuracy; real hardware adapters (ESP32 CSI, mmWave, thermal IR) are a documented roadmap item, none validated in v0.1. The Python deterministic proof is unchanged (rufield is off the signal-processing proof path).
 
 ### Security
+- **`homecore-api` (HA-wire-compat REST + WebSocket) beyond-SOTA security review — `GET /api/` auth-gate gap FIXED + WS event-stream lag-DoS robustness FIXED; auth/traversal/injection/info-leak dimensions confirmed clean (ADR-161 / ADR-130).** Network-facing review of the HA-wire-compat API layer (remote attack surface), not covered by the ADR-154–159 sweep — same scrutiny the sibling `wifi-densepose-engine` and `-bfld` reviews got. **Two real bugs fixed, each pinned by a fails-on-old test.**
+  - **HC-API-AUTH-01 (auth-gate gap, LOW) — `GET /api/` was unauthenticated; FIXED.** Every sibling REST route (`/api/config`, `/api/states`, `/api/services`, …) calls `BearerAuth::from_headers` first, but `rest::api_root` took no headers and unconditionally returned `200 {"message":"API running."}`. HA's `APIStatusView` inherits `requires_auth = True`, so an unauthenticated/wrong-token request to `/api/` must be **401** — HA clients use this status route as a token-validation probe, and a 200 both told a bad-token client its token was good and let an unauthenticated party confirm a live endpoint. Severity is LOW (the body is a static string — no entity/state data leaks), reported at true severity, not inflated. **Fix:** `api_root` now validates the bearer like its siblings. Pinned by `api_root_rejects_missing_bearer` + `api_root_rejects_wrong_bearer` (both 200→assert-401 on old code) and guarded by `api_root_accepts_correct_bearer`.
+  - **HC-WS-LAG-01 (DoS-adjacent silent failure, LOW) — `subscribe_events` killed the event stream on a broadcast lag; FIXED.** The per-subscription task matched `Err(_) => break` on both `broadcast::Receiver::recv()` arms, but `Lagged(n)` (a slow consumer falling >4,096 events — `EVENT_CHANNEL_CAPACITY` — behind) is **recoverable**: the bus doc itself says "Lagged receivers must re-sync", and HA's WS contract keeps the subscription alive across a lag. The old code treated the first lag as fatal, so after an event burst the client's stream went **permanently silent** with no error frame — a self-inflicted event-delivery DoS under load. **Fix:** `Lagged(_) => continue` (skip the dropped window, re-sync), `Closed => break`, on both the system and domain arms. Pinned by `subscription_survives_broadcast_lag` (subscribes, floods 6,000 filtered events past the 4,096 capacity to force a `Lagged`, then asserts a subsequent subscribed event is still delivered — 5s-timeout panic on old code).
+  - **Dimensions confirmed clean (with evidence, no invented issues):** (1) **AuthN/AuthZ** — all 7 other REST handlers (`get_config`/`get_states`/`get_state`/`set_state`/`delete_state`/`get_services`/`call_service`) gate on `BearerAuth::from_headers` → `LongLivedTokenStore::is_valid` before any work; the WS handshake validates the `auth` token against the **same** store before entering the command loop and the privileged commands are unreachable pre-`auth_ok` (HC-WS-01, already fixed). Token compare is a `HashSet::contains` (content-independent timing, not the byte-`==` oracle ADR-157 §B4 fixed in hardware) — no timing-oracle finding. No route skips the gate, no result-ignored check, no default/empty token accepted (`is_valid` rejects empty internally; `from_env` is non-dev). (2) **Path traversal** — **no route maps user input to a filesystem path** (state lives in an in-memory `DashMap`); `:entity_id` is funneled through `EntityId::parse`, a strict `[a-z0-9_]+\.[a-z0-9_]+` ASCII allowlist that rejects `..`, `/`, `\`, and absolute paths. No traversal surface exists. (3) **Injection** — no SQL, no shell/subprocess, no `format!`-into-response; `call_service`/`set_state` bodies are typed `serde_json::Value` passed to the in-process service registry (matches HA). (4) **Info-leak** — `ApiError` maps to fixed status + a `{message}` derived only from typed variants; `call_service`'s `ServiceError::HandlerFailed(String)` is integration-controlled (mirrors HA surfacing the handler error), not framework internals/paths/stack-traces (no ADR-080-class leak). (5) **CORS** is an explicit allowlist (`allow_credentials(false)`, HC-05 already fixed), not `permissive()`. (6) **De-magic** — no bare security-relevant literals in this crate worth extracting (`EVENT_CHANNEL_CAPACITY` already named in `homecore`; CORS dev-default ports are documented). `homecore-api --no-default-features`: **25→29 tests**, 0 failed (+2 api-root auth, +1 api-root accept-guard, +1 WS lag-survival); workspace green; Python deterministic proof unchanged (homecore-api is off the signal proof path). Review notes appended to ADR-161.
 - **`wifi-densepose-engine` governed-trust review — witness domain-separation gap FIXED + privacy monotonicity confirmed clean (ADR-137 / ADR-141 / ADR-032).** Beyond-SOTA correctness+security review of the security-critical composition root (the cycle enforcing RuView's privacy guarantees), not covered by the ADR-154–159 sweep. **One real witness-integrity bug fixed.** `witness_of` concatenated `model_version`, `calibration_version`, and `privacy_decision` boundary-to-boundary and left the variable-length evidence list without a count, so a string straddling a field boundary collided with a *different* trust decision — e.g. a per-room adapter id (ADR-150 §3.4, operator-influenceable) absorbing the leading bytes of the calibration epoch (`model="…cal:00a"`,`cal="b"`) yields the same witness as `model="…"`,`cal="cal:00ab"`. Two distinct privacy-relevant input tuples → one witness defeats the ADR-137 §2.7 "any privacy-relevant delta → different witness" tamper/drift audit. **Fix:** domain-tag the BLAKE3 hash (`ruview.engine.witness.v1`), write an explicit evidence count, and **length-prefix every field** (8-byte LE length ‖ bytes) — unambiguous framing regardless of contents. Witness-layout change by design (prior witness bytes invalidated); downstream consumers (`engine_bridge`, rufield) assert only witness *relationships* (`assert_ne`/`assert_eq` across runs), never absolute bytes, so nothing breaks. Pinned by two fails-on-old tests: `witness_distinguishes_model_calibration_boundary`, `witness_distinguishes_evidence_model_boundary`. **Dimensions confirmed clean (with evidence, no invented issues):** (1) **privacy monotonicity** — `effective_class` is recomputed each cycle from the active mode's floor with at most a single-step `demote_one` (clamped at `Restricted`), no cross-cycle state, proven over **all 5 modes** by `forced_contradiction_never_relaxes_class` (forced contradiction only ever raises the class byte; clean cycle == base); (2) **fail-closed** — empty cycle errors with no degenerate output (`empty_cycle_fails_closed`), single-node boundary characterized (`single_node_cycle_is_well_formed`), NaN coupling → `max(0.0)`→absent edge→at-risk (more restrictive); (3) **witness determinism** — no HashMap iteration / float formatting feeds the hash; (4) **mesh_guard** (ADR-032) — partition-risk → demotion path verified, thresholds already named documented fields. De-magicked the engine-construction literals (coherence accept gate, ADR-143 SLAM discovery + static-anchor thresholds) into named documented consts, value-identical, pinned by `engine_constants_match_prior_values`. `wifi-densepose-engine --no-default-features`: **27→33 tests**, 0 failed (+2 witness, +1 monotonicity property, +2 fail-closed boundary, +1 de-magic pin). Python deterministic proof unchanged (`f8e76f21…46f7a`, bit-exact — the engine is off the signal proof path). Review notes appended to ADR-137 (witness) and ADR-141 (monotonicity).
 - **ADR-141 BFLD privacy-bypass closed — `process_to_frame` now routes the payload through `PrivacyGate` (`wifi-densepose-bfld`).** `BfldPipeline::process_to_frame` stamped the emitted `BfldFrame` header with the active `PrivacyClass` but serialized the caller-supplied `BfldPayload` **unchanged** via `BfldFrame::from_payload`. A frame labeled `Anonymous`(2) or `Restricted`(3) therefore carried the full identity-leaky `compressed_angle_matrix` (the beamforming-angle identity surface) + amplitude/phase proxies + `csi_delta` — exactly the sections `PrivacyGate::demote` is documented and tested (`privacy_gate_demote.rs`) to strip at those classes. Because a `NetworkSink` accepts class ≥ `Derived`(1), such a frame would publish the identity surface across the node boundary despite its restrictive class byte; the class byte lied about payload content. **Fix:** after building the frame at the active class, apply `PrivacyGate::demote` to the same class — a no-op class transition that strips the sections that class forbids (research classes `Raw`/`Derived` keep the full payload). Pinned by three fails-on-old tests in `pipeline_to_frame.rs` (`…_at_anonymous_strips_identity_leaky_sections`, `…_in_privacy_mode_strips_amplitude_and_phase` — both FAILED pre-fix; `…_at_derived_preserves_full_payload` guards against over-stripping). Grade: privacy-bypass FIXED + regression-pinned.
 - **ADR-157 Milestone-1 B4 - constant-time HMAC sync-beacon tag compare (`wifi-densepose-hardware`).** `AuthenticatedBeacon::verify` compared the 8-byte HMAC-SHA256 tag with `self.hmac_tag == expected`, which short-circuits on the first differing byte and leaks, through verification latency, how many leading bytes an attacker's forged tag matched - a byte-by-byte tag-recovery oracle (~256*N trials instead of 256^N). Replaced with a hand-rolled branch-free `constant_time_tag_eq` (XOR-accumulate every byte difference into a single `u8`, no early exit, `#[inline(never)]` + `core::hint::black_box` to stop the optimizer reintroducing a short-circuit or a non-constant-time `memcmp`). **No new dependency** - ADR-157 had deferred this only to avoid adding the `subtle` crate; a fixed 8-byte compare needs none. Grade MEASURED (constant-time *construction*; micro-timing on a noisy host is a smoke check only, gated `#[ignore]`). Pinned by `tag_compare_is_constant_time_shape` (equal/first-differ/last-differ/all-differ/length-mismatch + an end-to-end `verify()` last-byte tamper), proven to fail on a last-byte-skipping constant-time bug. ADR-157 §8 B4 -> RESOLVED.