diff --git a/src/lib/signals/__tests__/fixtures/expected-bucketed-types.json b/src/lib/signals/__tests__/fixtures/expected-bucketed-types.json
new file mode 100644
index 000000000..cd5e00bb4
--- /dev/null
+++ b/src/lib/signals/__tests__/fixtures/expected-bucketed-types.json
@@ -0,0 +1,9 @@
+[
+  "WEIGHT",
+  "BLOOD_PRESSURE_SYS",
+  "BLOOD_PRESSURE_DIA",
+  "PULSE",
+  "BODY_FAT",
+  "SLEEP_DURATION",
+  "ACTIVITY_STEPS"
+]
diff --git a/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json b/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json
new file mode 100644
index 000000000..ef811a6a1
--- /dev/null
+++ b/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json
@@ -0,0 +1,218 @@
+{
+  "WEIGHT": {
+    "loinc": "29463-7",
+    "display": "Body weight",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "BODY_MASS_INDEX": {
+    "loinc": "39156-5",
+    "display": "Body mass index (BMI) [Ratio]",
+    "unit": "kg/m2",
+    "category": "vital-signs"
+  },
+  "PULSE": {
+    "loinc": "8867-4",
+    "display": "Heart rate",
+    "unit": "/min",
+    "category": "vital-signs"
+  },
+  "RESTING_HEART_RATE": {
+    "loinc": "40443-4",
+    "display": "Heart rate --resting",
+    "unit": "/min",
+    "category": "vital-signs"
+  },
+  "RESPIRATORY_RATE": {
+    "loinc": "9279-1",
+    "display": "Respiratory rate",
+    "unit": "/min",
+    "category": "vital-signs"
+  },
+  "BODY_TEMPERATURE": {
+    "loinc": "8310-5",
+    "display": "Body temperature",
+    "unit": "Cel",
+    "category": "vital-signs"
+  },
+  "OXYGEN_SATURATION": {
+    "loinc": "59408-5",
+    "display": "Oxygen saturation in Arterial blood by Pulse oximetry",
+    "unit": "%",
+    "category": "vital-signs"
+  },
+  "BODY_FAT": {
+    "loinc": "41982-0",
+    "display": "Percentage of body fat Measured",
+    "unit": "%",
+    "category": "vital-signs"
+  },
+  "VO2_MAX": {
+    "loinc": "96402-2",
+    "display": "Oxygen consumption maximum during exercise",
+    "unit": "mL/min/kg",
+    "category": "vital-signs"
+  },
+  "HEART_RATE_VARIABILITY": {
+    "loinc": "80404-7",
+    "display": "R-R interval.standard deviation (Heart rate variability)",
+    "unit": "ms",
+    "category": "vital-signs"
+  },
+  "ACTIVITY_STEPS": {
+    "loinc": "41950-7",
+    "display": "Number of steps in 24 hour Measured",
+    "unit": "{steps}",
+    "category": "activity"
+  },
+  "SLEEP_DURATION": {
+    "loinc": "93832-4",
+    "display": "Sleep duration",
+    "unit": "h",
+    "category": "activity"
+  },
+  "ACTIVE_ENERGY_BURNED": {
+    "loinc": "41981-2",
+    "display": "Calories burned",
+    "unit": "kcal",
+    "category": "activity"
+  },
+  "WALKING_SPEED": {
+    "loinc": "41957-2",
+    "display": "Gait speed [Velocity] Measured",
+    "unit": "m/s",
+    "category": "vital-signs"
+  },
+  "WALKING_ASYMMETRY": {
+    "loinc": "91557-1",
+    "display": "Walking asymmetry percentage",
+    "unit": "%",
+    "category": "vital-signs"
+  },
+  "WALKING_STEP_LENGTH": {
+    "loinc": "41955-6",
+    "display": "Step length Measured",
+    "unit": "m",
+    "category": "vital-signs"
+  },
+  "TOTAL_BODY_WATER": {
+    "loinc": "73704-9",
+    "display": "Body water by Bioelectrical impedance analysis",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "BONE_MASS": {
+    "loinc": "73708-0",
+    "display": "Bone mineral content by DXA",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "WALKING_DOUBLE_SUPPORT": {
+    "loinc": "HKQuantityTypeIdentifierWalkingDoubleSupportPercentage",
+    "display": "Walking double support percentage",
+    "unit": "%",
+    "category": "vital-signs"
+  },
+  "AUDIO_EXPOSURE_ENV": {
+    "loinc": "HKQuantityTypeIdentifierEnvironmentalAudioExposure",
+    "display": "Environmental audio exposure",
+    "unit": "dB[A]",
+    "category": "vital-signs"
+  },
+  "AUDIO_EXPOSURE_HEADPHONE": {
+    "loinc": "HKQuantityTypeIdentifierHeadphoneAudioExposure",
+    "display": "Headphone audio exposure",
+    "unit": "dB[A]",
+    "category": "vital-signs"
+  },
+  "FLIGHTS_CLIMBED": {
+    "loinc": "HKQuantityTypeIdentifierFlightsClimbed",
+    "display": "Flights climbed",
+    "unit": "{flights}",
+    "category": "activity"
+  },
+  "WALKING_RUNNING_DISTANCE": {
+    "loinc": "HKQuantityTypeIdentifierDistanceWalkingRunning",
+    "display": "Distance walking/running",
+    "unit": "m",
+    "category": "activity"
+  },
+  "TIME_IN_DAYLIGHT": {
+    "loinc": "HKQuantityTypeIdentifierTimeInDaylight",
+    "display": "Time in daylight",
+    "unit": "min",
+    "category": "activity"
+  },
+  "MUSCLE_MASS": {
+    "loinc": null,
+    "display": "Muscle mass",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "FAT_MASS": {
+    "loinc": null,
+    "display": "Fat mass",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "FAT_FREE_MASS": {
+    "loinc": null,
+    "display": "Fat-free mass",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "LEAN_BODY_MASS": {
+    "loinc": null,
+    "display": "Lean body mass",
+    "unit": "kg",
+    "category": "vital-signs"
+  },
+  "VISCERAL_FAT": {
+    "loinc": null,
+    "display": "Visceral fat",
+    "unit": "1",
+    "category": "vital-signs"
+  },
+  "CARDIO_RECOVERY": {
+    "loinc": "HKQuantityTypeIdentifierHeartRateRecoveryOneMinute",
+    "display": "Cardio recovery (1-minute heart-rate recovery)",
+    "unit": "/min",
+    "category": "vital-signs"
+  },
+  "WRIST_TEMPERATURE": {
+    "loinc": "HKQuantityTypeIdentifierAppleSleepingWristTemperature",
+    "display": "Sleeping wrist temperature",
+    "unit": "Cel",
+    "category": "vital-signs"
+  },
+  "FALL_COUNT": {
+    "loinc": "HKQuantityTypeIdentifierNumberOfTimesFallen",
+    "display": "Number of times fallen",
+    "unit": "{falls}",
+    "category": "activity"
+  },
+  "SIX_MINUTE_WALK_DISTANCE": {
+    "loinc": "HKQuantityTypeIdentifierSixMinuteWalkTestDistance",
+    "display": "Six-minute walk test distance",
+    "unit": "m",
+    "category": "activity"
+  },
+  "STAIR_ASCENT_SPEED": {
+    "loinc": "HKQuantityTypeIdentifierStairAscentSpeed",
+    "display": "Stair ascent speed",
+    "unit": "m/s",
+    "category": "vital-signs"
+  },
+  "STAIR_DESCENT_SPEED": {
+    "loinc": "HKQuantityTypeIdentifierStairDescentSpeed",
+    "display": "Stair descent speed",
+    "unit": "m/s",
+    "category": "vital-signs"
+  },
+  "BREATHING_DISTURBANCES": {
+    "loinc": "HKQuantityTypeIdentifierAppleSleepingBreathingDisturbances",
+    "display": "Sleeping breathing disturbances",
+    "unit": "{count}",
+    "category": "vital-signs"
+  }
+}
diff --git a/src/lib/signals/__tests__/registry-invariants.test.ts b/src/lib/signals/__tests__/registry-invariants.test.ts
new file mode 100644
index 000000000..d1538ba12
--- /dev/null
+++ b/src/lib/signals/__tests__/registry-invariants.test.ts
@@ -0,0 +1,99 @@
+/**
+ * Registry invariants — the drift guard that pins the SIGNAL REGISTRY to the
+ * values the per-surface tables carry today. Any edit that changes a derived
+ * table (FHIR coding, correlation eligibility, metric-status metadata) without
+ * intentionally updating the golden master fails here, so a registry flip stays
+ * a byte-for-byte no-op and accidental cross-surface drift cannot land.
+ *
+ * Golden masters under `./fixtures/*` were extracted verbatim from the
+ * hand-maintained tables at the v1.25 branch base; update them deliberately
+ * (and in lock-step with the registry) when a value genuinely changes.
+ */
+import { describe, expect, it } from "vitest";
+
+import {
+  METRIC_STATUS_IDS,
+  getMetricStatusMeta,
+} from "@/lib/insights/metric-status-registry";
+import { MEASUREMENT_LOINC } from "@/lib/fhir/loinc-map";
+import {
+  SIGNALS,
+  allSignals,
+  getSignal,
+  signalForMeasurementType,
+} from "@/lib/signals/registry";
+import { deriveMetricStatusRegistry } from "@/lib/signals/adapters/metric-status";
+import { deriveMeasurementLoinc } from "@/lib/signals/adapters/fhir";
+import { deriveBucketedTypes } from "@/lib/signals/adapters/correlation";
+
+import expectedMeasurementLoinc from "./fixtures/expected-measurement-loinc.json";
+import expectedBucketedTypes from "./fixtures/expected-bucketed-types.json";
+
+describe("signal registry — structural sanity", () => {
+  it("every entry's key matches its record key", () => {
+    for (const [key, signal] of Object.entries(SIGNALS)) {
+      expect(signal.key).toBe(key);
+    }
+  });
+
+  it("every signal carries a well-formed source for its kind", () => {
+    for (const signal of allSignals()) {
+      if (signal.kind === "biomarker") {
+        expect(signal.source.biomarkerKey.length).toBeGreaterThan(0);
+      } else {
+        expect(signal.source.measurementType.length).toBeGreaterThan(0);
+      }
+    }
+  });
+
+  it("mcp exposure follows Coach-snapshot inclusion", () => {
+    // The MCP get_metric_series enum is the Coach scope vocabulary, so a signal
+    // is MCP-readable iff it carries a Coach scope (and vice-versa).
+    for (const signal of allSignals()) {
+      const hasScope = signal.surfaces.coachSnapshot !== false;
+      expect(signal.surfaces.mcp).toBe(hasScope);
+    }
+  });
+
+  it("signalForMeasurementType round-trips every measurement/score signal", () => {
+    for (const signal of allSignals()) {
+      if (signal.kind === "biomarker") continue;
+      expect(signalForMeasurementType(signal.source.measurementType)).toBe(
+        signal,
+      );
+    }
+  });
+});
+
+describe("signal registry — metric-status projection equals the live table", () => {
+  it("registers every generic metric-status id", () => {
+    for (const id of METRIC_STATUS_IDS) {
+      expect(getSignal(id)).not.toBeNull();
+    }
+  });
+
+  it("derives each MetricStatusMeta byte-for-byte from the registry", () => {
+    const derived = deriveMetricStatusRegistry();
+    for (const id of METRIC_STATUS_IDS) {
+      expect(derived[id]).toEqual(getMetricStatusMeta(id));
+    }
+  });
+});
+
+describe("signal registry — FHIR table is byte-identical", () => {
+  it("derives MEASUREMENT_LOINC equal to the golden master", () => {
+    expect(deriveMeasurementLoinc()).toEqual(expectedMeasurementLoinc);
+  });
+
+  it("the live (flipped) MEASUREMENT_LOINC export equals the golden master", () => {
+    expect(MEASUREMENT_LOINC).toEqual(expectedMeasurementLoinc);
+  });
+});
+
+describe("signal registry — correlation table is byte-identical", () => {
+  it("derives BUCKETED_TYPES equal to the golden master (set semantics)", () => {
+    expect([...deriveBucketedTypes()].sort()).toEqual(
+      [...(expectedBucketedTypes as string[])].sort(),
+    );
+  });
+});
diff --git a/src/lib/signals/adapters/correlation.ts b/src/lib/signals/adapters/correlation.ts
new file mode 100644
index 000000000..777399d0a
--- /dev/null
+++ b/src/lib/signals/adapters/correlation.ts
@@ -0,0 +1,21 @@
+/**
+ * Adapter: derive the correlation engine's bucketed-type list from the
+ * registry. Replaces the hand-maintained `BUCKETED_TYPES` literal in
+ * `features.ts` — every signal flagged `surfaces.correlationEligible` projects
+ * to its DB `MeasurementType`. The list is consumed as a membership/iteration
+ * set (each type is read independently), so order is not semantically
+ * significant; the registry-invariant test compares it as a set.
+ */
+import type { MeasurementType } from "@/generated/prisma/client";
+import { allSignals } from "@/lib/signals/registry";
+
+/** The registry-derived correlation-eligible `MeasurementType` list. */
+export function deriveBucketedTypes(): MeasurementType[] {
+  const types: MeasurementType[] = [];
+  for (const signal of allSignals()) {
+    if (signal.kind === "biomarker") continue;
+    if (!signal.surfaces.correlationEligible) continue;
+    types.push(signal.source.measurementType);
+  }
+  return types;
+}
diff --git a/src/lib/signals/adapters/fhir.ts b/src/lib/signals/adapters/fhir.ts
new file mode 100644
index 000000000..1daafb530
--- /dev/null
+++ b/src/lib/signals/adapters/fhir.ts
@@ -0,0 +1,29 @@
+/**
+ * Adapter: derive the single-value `MeasurementType → FHIR coding` table from
+ * the registry. Replaces the hand-maintained `MEASUREMENT_LOINC` literal in
+ * `loinc-map.ts` — every signal that carries a `fhir` facet projects to one
+ * entry keyed by its DB `MeasurementType`. Signals without a `fhir` facet are
+ * absent (their value is surfaced as a local text concept elsewhere, or handled
+ * by a dedicated builder, e.g. BP panel / glucose context).
+ */
+import type { LoincMapping } from "@/lib/fhir/loinc-map";
+import { allSignals } from "@/lib/signals/registry";
+
+/** The registry-derived `MEASUREMENT_LOINC`, keyed by `MeasurementType` string. */
+export function deriveMeasurementLoinc(): Record<string, LoincMapping> {
+  const entries: Array<[string, LoincMapping]> = [];
+  for (const signal of allSignals()) {
+    if (signal.kind === "biomarker") continue;
+    if (!signal.fhir) continue;
+    entries.push([
+      signal.source.measurementType,
+      {
+        loinc: signal.fhir.loinc,
+        display: signal.fhir.display,
+        unit: signal.fhir.unit,
+        category: signal.fhir.category,
+      },
+    ]);
+  }
+  return Object.fromEntries(entries);
+}
diff --git a/src/lib/signals/adapters/metric-status.ts b/src/lib/signals/adapters/metric-status.ts
new file mode 100644
index 000000000..2470a6733
--- /dev/null
+++ b/src/lib/signals/adapters/metric-status.ts
@@ -0,0 +1,44 @@
+/**
+ * Adapter: project the registry back to the `MetricStatusMeta` shape the
+ * generic assessment path consumes today. The hand-written `REGISTRY` in
+ * `metric-status-registry.ts` stays the live source for the assessment card
+ * (untouched in this change); this projection exists so the registry-invariant
+ * test can assert the two agree field-for-field and flag any future drift.
+ */
+import {
+  METRIC_STATUS_IDS,
+  type MetricStatusMeta,
+  type MetricStatusMetricId,
+} from "@/lib/insights/metric-status-registry";
+import { getSignal } from "@/lib/signals/registry";
+
+/** Build the `MetricStatusMeta` for one registered metric-status id. */
+function metaFor(id: MetricStatusMetricId): MetricStatusMeta {
+  const signal = getSignal(id);
+  if (!signal || signal.kind === "biomarker") {
+    throw new Error(`signal registry: no measurement signal for "${id}"`);
+  }
+  // Build field-by-field, omitting the optional keys when absent so the
+  // projection matches the hand-written object shape exactly (deepEqual).
+  const meta: MetricStatusMeta = {
+    id,
+    measurementType: signal.source.measurementType,
+    displayName: signal.displayName,
+    unit: signal.unit,
+    direction: signal.direction,
+    archetype: signal.archetype,
+  };
+  if (signal.normalRange !== undefined) meta.normalRange = signal.normalRange;
+  if (signal.feverBandC !== undefined) meta.feverBandC = signal.feverBandC;
+  return meta;
+}
+
+/** The full registry-derived metric-status table, keyed by metric-status id. */
+export function deriveMetricStatusRegistry(): Record<
+  MetricStatusMetricId,
+  MetricStatusMeta
+> {
+  return Object.fromEntries(
+    METRIC_STATUS_IDS.map((id) => [id, metaFor(id)]),
+  ) as Record<MetricStatusMetricId, MetricStatusMeta>;
+}
diff --git a/src/lib/signals/registry.ts b/src/lib/signals/registry.ts
new file mode 100644
index 000000000..4f26dda81
--- /dev/null
+++ b/src/lib/signals/registry.ts
@@ -0,0 +1,1234 @@
+/**
+ * v1.25 — the SIGNAL REGISTRY backbone.
+ *
+ * One declarative table that describes a health signal ACROSS every surface
+ * it touches (DB measurement type, detail page, correlation engine, Coach
+ * snapshot, MCP read tool, FHIR coding). Today a single signal is described
+ * 8–16 times in independent tables keyed by slightly different vocabularies,
+ * and nothing fails the build when they disagree. This registry promotes the
+ * proto-registry in `metric-status-registry.ts` to the canonical definition
+ * and lets the per-surface tables DERIVE from it (see `./adapters/*`) instead
+ * of being hand-maintained beside it.
+ *
+ * Coexistence, not replacement: the DB enum stays the source of truth for
+ * persistence. The registry sits ABOVE it. Surfaces are flipped one at a time
+ * to read from the registry; the registry-invariant test pins every derived
+ * table byte-for-byte to the values the hand-written tables carry today, so a
+ * flip is a no-op diff and future drift fails CI.
+ *
+ * Adding a NEW signal (the clinical-signals wave): append ONE
+ * `SignalDefinition` object below, add its i18n keys, and — for a
+ * `measurement`/`score` — one Prisma enum member + migration. The derived
+ * tables (FHIR, correlation, …) light up with no further per-surface edits.
+ */
+import type { MeasurementType } from "@/generated/prisma/client";
+import type {
+  MetricArchetype,
+  MetricDirection,
+  MetricNormalRange,
+} from "@/lib/insights/metric-status-registry";
+import type { FhirObservationCategory } from "@/lib/fhir/loinc-map";
+import { FEVER_BAND_C } from "@/lib/clinical-floors";
+
+/** Discriminator: a device/manual reading, a lab biomarker, or a computed score. */
+export type SignalKind = "measurement" | "biomarker" | "score";
+
+/** Reuse the assessment registry's direction vocabulary verbatim. */
+export type SignalDirection = MetricDirection;
+
+/** Coarse population placement band; the user's own baseline still leads. */
+export type SignalBand = MetricNormalRange;
+
+/**
+ * FHIR R4 coding facet. Field names align with `loinc-map.ts`'s `LoincMapping`
+ * (`unit` is the UCUM string, also used as the `code`) so the FHIR adapter is a
+ * straight projection with no renaming.
+ */
+export interface SignalFhirCoding {
+  /** LOINC code, or null when no stable LOINC applies (local text fallback). */
+  loinc: string | null;
+  display: string;
+  /** UCUM unit string (also used as the FHIR `code`). */
+  unit: string;
+  category: FhirObservationCategory;
+}
+
+/** Chart-overlay facet. Typed loosely (string overlayKey) to keep the backbone free of the dashboard-layout runtime dep. */
+export interface SignalChart {
+  overlayKey: string;
+  color?: string;
+  yAxisUnit?: string;
+  /** Display rescale (e.g. m/s → km/h); applied at the chart edge only. */
+  valueScale?: number;
+}
+
+/**
+ * Per-surface eligibility — declarative flags, not branches scattered across
+ * files. `coachSnapshot.scope` is the Coach scope-source token (typed as a
+ * string here so the backbone does not depend on the coach module; the coach
+ * flip will tighten it to `CoachScopeSource`).
+ */
+export interface SignalSurfaces {
+  /** Mount the generic HealthKit/biomarker detail template. */
+  detailPage: boolean;
+  /** Feed the FDR correlation channels (⇒ `BUCKETED_TYPES`). */
+  correlationEligible: boolean;
+  /** Coach snapshot inclusion + its scope token, or `false` to opt out. */
+  coachSnapshot: false | { scope: string };
+  /** Exposed to the MCP `get_metric_series` / search inventory. */
+  mcp: boolean;
+}
+
+interface SignalCommon {
+  /** Stable signal key — the ONE vocabulary every surface speaks. */
+  key: string;
+  /** i18n key prefix resolving `.title`/`.description`/`.chartTitle`/`.emptyState.*`. Optional until the clinical-signals wave fills it per signal. */
+  i18nPrefix?: string;
+  /** Stable English display name (the model localises its own prose). */
+  displayName: string;
+  /** Canonical storage unit (matches the DB column semantics). */
+  unit: string;
+  direction: SignalDirection;
+  archetype: MetricArchetype;
+  normalRange?: SignalBand;
+  /** Single-reading fever band line (°C) for temperature signals. */
+  feverBandC?: number;
+  /** Richer clinical bands defer to a `reference-ranges.ts` entry by key. */
+  referenceMetric?: string;
+  /** Cross-source dedup ladder key; omit ⇒ not cross-source-deduped. */
+  sourcePriorityKey?: string;
+  chart?: SignalChart;
+  surfaces: SignalSurfaces;
+  fhir?: SignalFhirCoding;
+}
+
+/** How a `measurement`/`score` signal is sourced from the DB enum. */
+export interface MeasurementSignalSource {
+  measurementType: MeasurementType;
+  /** Fallback measurement type (e.g. an SDNN→RMSSD HRV proxy). */
+  fallbackMeasurementType?: MeasurementType;
+}
+
+/** How a `biomarker` signal is sourced from the labs catalog. */
+export interface BiomarkerSignalSource {
+  biomarkerKey: string;
+}
+
+/**
+ * The canonical cross-surface signal definition, discriminated on `kind`.
+ * `measurement` and `score` both resolve to a `MeasurementType`; `biomarker`
+ * resolves to a labs-catalog key.
+ */
+export type SignalDefinition =
+  | (SignalCommon & { kind: "measurement"; source: MeasurementSignalSource })
+  | (SignalCommon & { kind: "score"; source: MeasurementSignalSource })
+  | (SignalCommon & { kind: "biomarker"; source: BiomarkerSignalSource });
+
+/** Convenience: build a Coach-snapshot facet from a scope token. */
+function coachScope(scope: string): { scope: string } {
+  return { scope };
+}
+
+/**
+ * The registry. Keyed by stable signal key. Generic HealthKit signals key by
+ * their `metric-status-registry` id (STEPS, RESTING_HEART_RATE, …); the six
+ * specialised signals (WEIGHT/BMI/PULSE/BODY_FAT/BP_SYS/BP_DIA) key by their
+ * `MeasurementType` and carry `detailPage:false` so the generic template never
+ * double-renders them — they still appear in the cross-surface indices (FHIR,
+ * correlation, Coach, MCP).
+ *
+ * Every value here is the value the hand-written per-surface table carries
+ * today; the registry-invariant test pins them byte-for-byte.
+ */
+export const SIGNALS: Record<string, SignalDefinition> = {
+  // ── physiological-vital ──────────────────────────────────────────────
+  RESTING_HEART_RATE: {
+    key: "RESTING_HEART_RATE",
+    kind: "measurement",
+    source: { measurementType: "RESTING_HEART_RATE" },
+    sourcePriorityKey: "restingHeartRate",
+    i18nPrefix: "insights.restingHr",
+    displayName: "Resting heart rate",
+    unit: "bpm",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    normalRange: { low: 50, high: 100 },
+    referenceMetric: "RESTING_HEART_RATE",
+    chart: { overlayKey: "restingHr", color: "#ff5555", yAxisUnit: "bpm" },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("resting_hr"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "40443-4",
+      display: "Heart rate --resting",
+      unit: "/min",
+      category: "vital-signs",
+    },
+  },
+  HEART_RATE_VARIABILITY: {
+    key: "HEART_RATE_VARIABILITY",
+    kind: "measurement",
+    source: { measurementType: "HEART_RATE_VARIABILITY" },
+    sourcePriorityKey: "hrv",
+    displayName: "Heart-rate variability (SDNN)",
+    unit: "ms",
+    direction: "higher-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("hrv"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "80404-7",
+      display: "R-R interval.standard deviation (Heart rate variability)",
+      unit: "ms",
+      category: "vital-signs",
+    },
+  },
+  OXYGEN_SATURATION: {
+    key: "OXYGEN_SATURATION",
+    kind: "measurement",
+    source: { measurementType: "OXYGEN_SATURATION" },
+    sourcePriorityKey: "spo2",
+    displayName: "Blood oxygen (SpO₂)",
+    unit: "%",
+    direction: "higher-better",
+    archetype: "physiological-vital",
+    normalRange: { low: 95, high: 100 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("spo2"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "59408-5",
+      display: "Oxygen saturation in Arterial blood by Pulse oximetry",
+      unit: "%",
+      category: "vital-signs",
+    },
+  },
+  RESPIRATORY_RATE: {
+    key: "RESPIRATORY_RATE",
+    kind: "measurement",
+    source: { measurementType: "RESPIRATORY_RATE" },
+    sourcePriorityKey: "respiratoryRate",
+    displayName: "Respiratory rate",
+    unit: "breaths/min",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    normalRange: { low: 12, high: 20 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("respiratory_rate"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "9279-1",
+      display: "Respiratory rate",
+      unit: "/min",
+      category: "vital-signs",
+    },
+  },
+  BODY_TEMPERATURE: {
+    key: "BODY_TEMPERATURE",
+    kind: "measurement",
+    source: { measurementType: "BODY_TEMPERATURE" },
+    sourcePriorityKey: "bodyTemperature",
+    displayName: "Body temperature",
+    unit: "°C",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    normalRange: { low: 36.1, high: 37.2 },
+    feverBandC: FEVER_BAND_C,
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("body_temp"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "8310-5",
+      display: "Body temperature",
+      unit: "Cel",
+      category: "vital-signs",
+    },
+  },
+  SKIN_TEMPERATURE: {
+    key: "SKIN_TEMPERATURE",
+    kind: "measurement",
+    source: { measurementType: "SKIN_TEMPERATURE" },
+    sourcePriorityKey: "skinTemperature",
+    displayName: "Wrist skin temperature",
+    unit: "°C",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("skin_temp"),
+      mcp: true,
+    },
+  },
+  BLOOD_GLUCOSE: {
+    key: "BLOOD_GLUCOSE",
+    kind: "measurement",
+    source: { measurementType: "BLOOD_GLUCOSE" },
+    displayName: "Blood glucose",
+    unit: "mg/dL",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    normalRange: { low: 70, high: 140 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("glucose"),
+      mcp: true,
+    },
+  },
+  WALKING_HEART_RATE_AVERAGE: {
+    key: "WALKING_HEART_RATE_AVERAGE",
+    kind: "measurement",
+    source: { measurementType: "WALKING_HEART_RATE_AVERAGE" },
+    displayName: "Walking heart rate",
+    unit: "bpm",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_hr"),
+      mcp: true,
+    },
+  },
+  PULSE_WAVE_VELOCITY: {
+    key: "PULSE_WAVE_VELOCITY",
+    kind: "measurement",
+    source: { measurementType: "PULSE_WAVE_VELOCITY" },
+    displayName: "Pulse-wave velocity",
+    unit: "m/s",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    normalRange: { low: 0, high: 10 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("pulse_wave_velocity"),
+      mcp: true,
+    },
+  },
+  VASCULAR_AGE: {
+    key: "VASCULAR_AGE",
+    kind: "measurement",
+    source: { measurementType: "VASCULAR_AGE" },
+    displayName: "Vascular age",
+    unit: "years",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("vascular_age"),
+      mcp: true,
+    },
+  },
+  CARDIO_RECOVERY: {
+    key: "CARDIO_RECOVERY",
+    kind: "measurement",
+    source: { measurementType: "CARDIO_RECOVERY" },
+    displayName: "Cardio recovery",
+    unit: "bpm",
+    direction: "higher-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierHeartRateRecoveryOneMinute",
+      display: "Cardio recovery (1-minute heart-rate recovery)",
+      unit: "/min",
+      category: "vital-signs",
+    },
+  },
+  WRIST_TEMPERATURE: {
+    key: "WRIST_TEMPERATURE",
+    kind: "measurement",
+    source: { measurementType: "WRIST_TEMPERATURE" },
+    displayName: "Wrist temperature",
+    unit: "°C",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierAppleSleepingWristTemperature",
+      display: "Sleeping wrist temperature",
+      unit: "Cel",
+      category: "vital-signs",
+    },
+  },
+  ANS_CHARGE: {
+    key: "ANS_CHARGE",
+    kind: "measurement",
+    source: { measurementType: "ANS_CHARGE" },
+    displayName: "ANS charge",
+    unit: "score",
+    direction: "higher-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  AVERAGE_HEART_RATE: {
+    key: "AVERAGE_HEART_RATE",
+    kind: "measurement",
+    source: { measurementType: "AVERAGE_HEART_RATE" },
+    displayName: "Average heart rate",
+    unit: "bpm",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  MAX_HEART_RATE: {
+    key: "MAX_HEART_RATE",
+    kind: "measurement",
+    source: { measurementType: "MAX_HEART_RATE" },
+    displayName: "Max heart rate",
+    unit: "bpm",
+    direction: "target-band",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  // ── activity-fitness ─────────────────────────────────────────────────
+  STEPS: {
+    key: "STEPS",
+    kind: "measurement",
+    source: { measurementType: "ACTIVITY_STEPS" },
+    sourcePriorityKey: "steps",
+    displayName: "Steps",
+    unit: "steps/day",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    normalRange: { low: 8000, high: 15000 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: true,
+      coachSnapshot: coachScope("steps"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "41950-7",
+      display: "Number of steps in 24 hour Measured",
+      unit: "{steps}",
+      category: "activity",
+    },
+  },
+  ACTIVE_ENERGY: {
+    key: "ACTIVE_ENERGY",
+    kind: "measurement",
+    source: { measurementType: "ACTIVE_ENERGY_BURNED" },
+    sourcePriorityKey: "activeEnergy",
+    displayName: "Active energy",
+    unit: "kcal/day",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("active_energy"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "41981-2",
+      display: "Calories burned",
+      unit: "kcal",
+      category: "activity",
+    },
+  },
+  FLIGHTS_CLIMBED: {
+    key: "FLIGHTS_CLIMBED",
+    kind: "measurement",
+    source: { measurementType: "FLIGHTS_CLIMBED" },
+    sourcePriorityKey: "flightsClimbed",
+    displayName: "Flights climbed",
+    unit: "flights/day",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("flights"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierFlightsClimbed",
+      display: "Flights climbed",
+      unit: "{flights}",
+      category: "activity",
+    },
+  },
+  WALKING_RUNNING_DISTANCE: {
+    key: "WALKING_RUNNING_DISTANCE",
+    kind: "measurement",
+    source: { measurementType: "WALKING_RUNNING_DISTANCE" },
+    sourcePriorityKey: "walkingRunningDistance",
+    displayName: "Walking + running distance",
+    unit: "m/day",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("distance"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierDistanceWalkingRunning",
+      display: "Distance walking/running",
+      unit: "m",
+      category: "activity",
+    },
+  },
+  TIME_IN_DAYLIGHT: {
+    key: "TIME_IN_DAYLIGHT",
+    kind: "measurement",
+    source: { measurementType: "TIME_IN_DAYLIGHT" },
+    displayName: "Time in daylight",
+    unit: "min/day",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    normalRange: { low: 30, high: 120 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("daylight"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierTimeInDaylight",
+      display: "Time in daylight",
+      unit: "min",
+      category: "activity",
+    },
+  },
+  VO2_MAX: {
+    key: "VO2_MAX",
+    kind: "measurement",
+    source: { measurementType: "VO2_MAX" },
+    sourcePriorityKey: "vo2Max",
+    displayName: "VO₂ max (cardio fitness)",
+    unit: "mL/(kg·min)",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("vo2_max"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "96402-2",
+      display: "Oxygen consumption maximum during exercise",
+      unit: "mL/min/kg",
+      category: "vital-signs",
+    },
+  },
+  DAY_STRAIN: {
+    key: "DAY_STRAIN",
+    kind: "measurement",
+    source: { measurementType: "DAY_STRAIN" },
+    displayName: "Day strain",
+    unit: "score",
+    direction: "target-band",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  WORKOUT_STRAIN: {
+    key: "WORKOUT_STRAIN",
+    kind: "measurement",
+    source: { measurementType: "WORKOUT_STRAIN" },
+    displayName: "Workout strain",
+    unit: "score",
+    direction: "target-band",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  CARDIO_LOAD: {
+    key: "CARDIO_LOAD",
+    kind: "measurement",
+    source: { measurementType: "CARDIO_LOAD" },
+    displayName: "Cardio load",
+    unit: "score",
+    direction: "target-band",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  ENERGY_EXPENDITURE_KJ: {
+    key: "ENERGY_EXPENDITURE_KJ",
+    kind: "measurement",
+    source: { measurementType: "ENERGY_EXPENDITURE_KJ" },
+    displayName: "Energy expenditure",
+    unit: "kJ",
+    direction: "higher-better",
+    archetype: "activity-fitness",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  // ── body-composition ─────────────────────────────────────────────────
+  TOTAL_BODY_WATER: {
+    key: "TOTAL_BODY_WATER",
+    kind: "measurement",
+    source: { measurementType: "TOTAL_BODY_WATER" },
+    displayName: "Total body water",
+    unit: "kg",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("total_body_water"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "73704-9",
+      display: "Body water by Bioelectrical impedance analysis",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  BONE_MASS: {
+    key: "BONE_MASS",
+    kind: "measurement",
+    source: { measurementType: "BONE_MASS" },
+    displayName: "Bone mass",
+    unit: "kg",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("bone_mass"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "73708-0",
+      display: "Bone mineral content by DXA",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  FAT_FREE_MASS: {
+    key: "FAT_FREE_MASS",
+    kind: "measurement",
+    source: { measurementType: "FAT_FREE_MASS" },
+    displayName: "Fat-free mass",
+    unit: "kg",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("fat_free_mass"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: null,
+      display: "Fat-free mass",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  FAT_MASS: {
+    key: "FAT_MASS",
+    kind: "measurement",
+    source: { measurementType: "FAT_MASS" },
+    displayName: "Fat mass",
+    unit: "kg",
+    direction: "lower-better",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("fat_mass"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: null,
+      display: "Fat mass",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  MUSCLE_MASS: {
+    key: "MUSCLE_MASS",
+    kind: "measurement",
+    source: { measurementType: "MUSCLE_MASS" },
+    displayName: "Muscle mass",
+    unit: "kg",
+    direction: "higher-better",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("muscle_mass"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: null,
+      display: "Muscle mass",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  LEAN_BODY_MASS: {
+    key: "LEAN_BODY_MASS",
+    kind: "measurement",
+    source: { measurementType: "LEAN_BODY_MASS" },
+    displayName: "Lean body mass",
+    unit: "kg",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("lean_body_mass"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: null,
+      display: "Lean body mass",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  VISCERAL_FAT: {
+    key: "VISCERAL_FAT",
+    kind: "measurement",
+    source: { measurementType: "VISCERAL_FAT" },
+    displayName: "Visceral fat rating",
+    unit: "rating",
+    direction: "lower-better",
+    archetype: "body-composition",
+    normalRange: { low: 1, high: 12 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("visceral_fat"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: null,
+      display: "Visceral fat",
+      unit: "1",
+      category: "vital-signs",
+    },
+  },
+  // ── mobility-gait ────────────────────────────────────────────────────
+  WALKING_STEADINESS: {
+    key: "WALKING_STEADINESS",
+    kind: "measurement",
+    source: { measurementType: "WALKING_STEADINESS" },
+    displayName: "Walking steadiness",
+    unit: "%",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    normalRange: { low: 50, high: 100 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_steadiness"),
+      mcp: true,
+    },
+  },
+  WALKING_ASYMMETRY: {
+    key: "WALKING_ASYMMETRY",
+    kind: "measurement",
+    source: { measurementType: "WALKING_ASYMMETRY" },
+    displayName: "Walking asymmetry",
+    unit: "%",
+    direction: "lower-better",
+    archetype: "mobility-gait",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_asymmetry"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "91557-1",
+      display: "Walking asymmetry percentage",
+      unit: "%",
+      category: "vital-signs",
+    },
+  },
+  WALKING_DOUBLE_SUPPORT: {
+    key: "WALKING_DOUBLE_SUPPORT",
+    kind: "measurement",
+    source: { measurementType: "WALKING_DOUBLE_SUPPORT" },
+    displayName: "Double-support time",
+    unit: "%",
+    direction: "lower-better",
+    archetype: "mobility-gait",
+    normalRange: { low: 20, high: 40 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_double_support"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierWalkingDoubleSupportPercentage",
+      display: "Walking double support percentage",
+      unit: "%",
+      category: "vital-signs",
+    },
+  },
+  WALKING_STEP_LENGTH: {
+    key: "WALKING_STEP_LENGTH",
+    kind: "measurement",
+    source: { measurementType: "WALKING_STEP_LENGTH" },
+    displayName: "Step length",
+    unit: "m",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_step_length"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "41955-6",
+      display: "Step length Measured",
+      unit: "m",
+      category: "vital-signs",
+    },
+  },
+  WALKING_SPEED: {
+    key: "WALKING_SPEED",
+    kind: "measurement",
+    source: { measurementType: "WALKING_SPEED" },
+    displayName: "Walking speed",
+    unit: "m/s",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    normalRange: { low: 1.2, high: 1.4 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("walking_speed"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "41957-2",
+      display: "Gait speed [Velocity] Measured",
+      unit: "m/s",
+      category: "vital-signs",
+    },
+  },
+  FALL_COUNT: {
+    key: "FALL_COUNT",
+    kind: "measurement",
+    source: { measurementType: "FALL_COUNT" },
+    displayName: "Falls",
+    unit: "falls/day",
+    direction: "lower-better",
+    archetype: "mobility-gait",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierNumberOfTimesFallen",
+      display: "Number of times fallen",
+      unit: "{falls}",
+      category: "activity",
+    },
+  },
+  SIX_MINUTE_WALK_DISTANCE: {
+    key: "SIX_MINUTE_WALK_DISTANCE",
+    kind: "measurement",
+    source: { measurementType: "SIX_MINUTE_WALK_DISTANCE" },
+    displayName: "Six-minute walk distance",
+    unit: "m",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    normalRange: { low: 400, high: 700 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierSixMinuteWalkTestDistance",
+      display: "Six-minute walk test distance",
+      unit: "m",
+      category: "activity",
+    },
+  },
+  STAIR_ASCENT_SPEED: {
+    key: "STAIR_ASCENT_SPEED",
+    kind: "measurement",
+    source: { measurementType: "STAIR_ASCENT_SPEED" },
+    displayName: "Stair ascent speed",
+    unit: "m/s",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierStairAscentSpeed",
+      display: "Stair ascent speed",
+      unit: "m/s",
+      category: "vital-signs",
+    },
+  },
+  STAIR_DESCENT_SPEED: {
+    key: "STAIR_DESCENT_SPEED",
+    kind: "measurement",
+    source: { measurementType: "STAIR_DESCENT_SPEED" },
+    displayName: "Stair descent speed",
+    unit: "m/s",
+    direction: "higher-better",
+    archetype: "mobility-gait",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierStairDescentSpeed",
+      display: "Stair descent speed",
+      unit: "m/s",
+      category: "vital-signs",
+    },
+  },
+  // ── environmental-exposure ───────────────────────────────────────────
+  AUDIO_EXPOSURE_ENV: {
+    key: "AUDIO_EXPOSURE_ENV",
+    kind: "measurement",
+    source: { measurementType: "AUDIO_EXPOSURE_ENV" },
+    displayName: "Environmental sound exposure",
+    unit: "dBA",
+    direction: "lower-better",
+    archetype: "environmental-exposure",
+    normalRange: { low: 0, high: 80 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("audio_env"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierEnvironmentalAudioExposure",
+      display: "Environmental audio exposure",
+      unit: "dB[A]",
+      category: "vital-signs",
+    },
+  },
+  AUDIO_EXPOSURE_HEADPHONE: {
+    key: "AUDIO_EXPOSURE_HEADPHONE",
+    kind: "measurement",
+    source: { measurementType: "AUDIO_EXPOSURE_HEADPHONE" },
+    displayName: "Headphone audio exposure",
+    unit: "dBA",
+    direction: "lower-better",
+    archetype: "environmental-exposure",
+    normalRange: { low: 0, high: 80 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("audio_headphone"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierHeadphoneAudioExposure",
+      display: "Headphone audio exposure",
+      unit: "dB[A]",
+      category: "vital-signs",
+    },
+  },
+  AUDIO_EXPOSURE_EVENT: {
+    key: "AUDIO_EXPOSURE_EVENT",
+    kind: "measurement",
+    source: { measurementType: "AUDIO_EXPOSURE_EVENT" },
+    displayName: "Loud-exposure events",
+    unit: "events",
+    direction: "lower-better",
+    archetype: "environmental-exposure",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: coachScope("audio_event"),
+      mcp: true,
+    },
+  },
+  // ── sleep (dedicated template) ───────────────────────────────────────
+  SLEEP_DURATION: {
+    key: "SLEEP_DURATION",
+    kind: "measurement",
+    source: { measurementType: "SLEEP_DURATION" },
+    sourcePriorityKey: "sleep",
+    displayName: "Sleep duration",
+    unit: "min",
+    direction: "target-band",
+    archetype: "sleep",
+    normalRange: { low: 420, high: 540 },
+    surfaces: {
+      detailPage: true,
+      correlationEligible: true,
+      coachSnapshot: coachScope("sleep"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "93832-4",
+      display: "Sleep duration",
+      unit: "h",
+      category: "activity",
+    },
+  },
+  BREATHING_DISTURBANCES: {
+    key: "BREATHING_DISTURBANCES",
+    kind: "measurement",
+    source: { measurementType: "BREATHING_DISTURBANCES" },
+    displayName: "Sleep breathing disturbances",
+    unit: "count",
+    direction: "lower-better",
+    archetype: "sleep",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+    fhir: {
+      loinc: "HKQuantityTypeIdentifierAppleSleepingBreathingDisturbances",
+      display: "Sleeping breathing disturbances",
+      unit: "{count}",
+      category: "vital-signs",
+    },
+  },
+  SLEEP_SCORE: {
+    key: "SLEEP_SCORE",
+    kind: "measurement",
+    source: { measurementType: "SLEEP_SCORE" },
+    displayName: "Sleep score",
+    unit: "score",
+    direction: "higher-better",
+    archetype: "sleep",
+    surfaces: {
+      detailPage: true,
+      correlationEligible: false,
+      coachSnapshot: false,
+      mcp: false,
+    },
+  },
+  // ── specialised metrics (bespoke status files; detailPage:false) ──────
+  // These keep their dedicated scopes + status generators; they register
+  // only so the cross-surface indices (FHIR, correlation, Coach, MCP) see
+  // them without routing them through the generic detail template.
+  WEIGHT: {
+    key: "WEIGHT",
+    kind: "measurement",
+    source: { measurementType: "WEIGHT" },
+    sourcePriorityKey: "weight",
+    displayName: "Weight",
+    unit: "kg",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: true,
+      coachSnapshot: coachScope("weight"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "29463-7",
+      display: "Body weight",
+      unit: "kg",
+      category: "vital-signs",
+    },
+  },
+  BODY_MASS_INDEX: {
+    key: "BODY_MASS_INDEX",
+    kind: "measurement",
+    source: { measurementType: "BODY_MASS_INDEX" },
+    displayName: "Body mass index",
+    unit: "kg/m²",
+    direction: "target-band",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: false,
+      coachSnapshot: coachScope("bmi"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "39156-5",
+      display: "Body mass index (BMI) [Ratio]",
+      unit: "kg/m2",
+      category: "vital-signs",
+    },
+  },
+  PULSE: {
+    key: "PULSE",
+    kind: "measurement",
+    source: { measurementType: "PULSE" },
+    sourcePriorityKey: "pulse",
+    displayName: "Pulse",
+    unit: "bpm",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: true,
+      coachSnapshot: coachScope("pulse"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "8867-4",
+      display: "Heart rate",
+      unit: "/min",
+      category: "vital-signs",
+    },
+  },
+  BODY_FAT: {
+    key: "BODY_FAT",
+    kind: "measurement",
+    source: { measurementType: "BODY_FAT" },
+    sourcePriorityKey: "bodyFat",
+    displayName: "Body fat",
+    unit: "%",
+    direction: "lower-better",
+    archetype: "body-composition",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: true,
+      coachSnapshot: coachScope("body_fat"),
+      mcp: true,
+    },
+    fhir: {
+      loinc: "41982-0",
+      display: "Percentage of body fat Measured",
+      unit: "%",
+      category: "vital-signs",
+    },
+  },
+  BLOOD_PRESSURE_SYS: {
+    key: "BLOOD_PRESSURE_SYS",
+    kind: "measurement",
+    source: { measurementType: "BLOOD_PRESSURE_SYS" },
+    sourcePriorityKey: "bloodPressure",
+    displayName: "Blood pressure (systolic)",
+    unit: "mmHg",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: true,
+      coachSnapshot: coachScope("bp"),
+      mcp: true,
+    },
+  },
+  BLOOD_PRESSURE_DIA: {
+    key: "BLOOD_PRESSURE_DIA",
+    kind: "measurement",
+    source: { measurementType: "BLOOD_PRESSURE_DIA" },
+    sourcePriorityKey: "bloodPressure",
+    displayName: "Blood pressure (diastolic)",
+    unit: "mmHg",
+    direction: "lower-better",
+    archetype: "physiological-vital",
+    surfaces: {
+      detailPage: false,
+      correlationEligible: true,
+      coachSnapshot: coachScope("bp"),
+      mcp: true,
+    },
+  },
+};
+
+/** Type guard: narrow an arbitrary string to a registered signal key. */
+export function isSignalKey(key: string): boolean {
+  return Object.prototype.hasOwnProperty.call(SIGNALS, key);
+}
+
+/** Resolve a signal by its key, or null when unregistered. */
+export function getSignal(key: string): SignalDefinition | null {
+  return isSignalKey(key) ? SIGNALS[key] : null;
+}
+
+/** Every registered signal, in declaration order. */
+export function allSignals(): SignalDefinition[] {
+  return Object.values(SIGNALS);
+}
+
+/** Reverse index: DB `MeasurementType` → the signal it backs (built once). */
+const MEASUREMENT_TYPE_TO_SIGNAL = new Map<MeasurementType, SignalDefinition>(
+  allSignals()
+    .filter(
+      (s): s is Extract<SignalDefinition, { kind: "measurement" | "score" }> =>
+        s.kind === "measurement" || s.kind === "score",
+    )
+    .map((s) => [s.source.measurementType, s]),
+);
+
+/** Resolve the signal a `MeasurementType` backs, or null when unregistered. */
+export function signalForMeasurementType(
+  type: MeasurementType,
+): SignalDefinition | null {
+  return MEASUREMENT_TYPE_TO_SIGNAL.get(type) ?? null;
+}