diff --git a/src/lib/__tests__/clinical-floors.test.ts b/src/lib/__tests__/clinical-floors.test.ts
new file mode 100644
index 000000000..c22b4e4b8
--- /dev/null
+++ b/src/lib/__tests__/clinical-floors.test.ts
@@ -0,0 +1,69 @@
+/**
+ * D3-H1 coverage — the clinical safety floors are ONE source of truth.
+ *
+ * Before v1.21.0 the "is this BP a crisis?" floors lived in three modules with
+ * a divergent diastolic value (notification engine + Coach 180/120, dashboard
+ * hero 180/110), so a 170/112 reading lit the hero banner yet never tripped the
+ * alarm. This suite pins that every consumer now resolves the SAME canonical
+ * constants from `@/lib/clinical-floors`, so the three surfaces can never drift
+ * apart again without a test failure.
+ */
+import { describe, it, expect } from "vitest";
+
+import {
+  BP_SYS_CRITICAL,
+  BP_DIA_CRITICAL,
+  BP_SYS_HYPOTENSIVE_FLOOR,
+  GLUCOSE_HYPO_FLOOR,
+  GLUCOSE_HYPO_SEVERE_FLOOR,
+  GLUCOSE_HYPER_FLOOR,
+  FEVER_BAND_C,
+  FEVER_RED_FLAG_C,
+  SPO2_RED_FLAG_PCT,
+} from "@/lib/clinical-floors";
+import {
+  BP_SYS_HYPERTENSIVE,
+  BP_DIA_HYPERTENSIVE,
+  BP_SYS_HYPOTENSIVE,
+  GLUCOSE_HYPO,
+  GLUCOSE_HYPO_SEVERE,
+  GLUCOSE_HYPER,
+} from "@/lib/illness/safety-floors";
+import { getMetricStatusMeta } from "@/lib/insights/metric-status-registry";
+
+describe("clinical-floors — single source of truth", () => {
+  it("uses the guideline-correct hypertensive-crisis floors (180/120)", () => {
+    // ACC/AHA hypertensive-urgency floor: the diastolic floor is 120, NOT the
+    // former hero-only 110 that fired the banner on calmer readings.
+    expect(BP_SYS_CRITICAL).toBe(180);
+    expect(BP_DIA_CRITICAL).toBe(120);
+  });
+
+  it("safety-floors notification engine re-exports the canonical constants", () => {
+    expect(BP_SYS_HYPERTENSIVE).toBe(BP_SYS_CRITICAL);
+    expect(BP_DIA_HYPERTENSIVE).toBe(BP_DIA_CRITICAL);
+    expect(BP_SYS_HYPOTENSIVE).toBe(BP_SYS_HYPOTENSIVE_FLOOR);
+    expect(GLUCOSE_HYPO).toBe(GLUCOSE_HYPO_FLOOR);
+    expect(GLUCOSE_HYPO_SEVERE).toBe(GLUCOSE_HYPO_SEVERE_FLOOR);
+    expect(GLUCOSE_HYPER).toBe(GLUCOSE_HYPER_FLOOR);
+  });
+
+  it("the status registry's fever band binds to the canonical FEVER_BAND_C", () => {
+    expect(getMetricStatusMeta("BODY_TEMPERATURE")?.feverBandC).toBe(
+      FEVER_BAND_C,
+    );
+  });
+
+  it("the single-reading fever band sits below the sustained-fever escalation", () => {
+    // Two intentional lines for two questions — but both from one module, so
+    // they are visibly a pair (D3-L1), not unrelated magic numbers.
+    expect(FEVER_BAND_C).toBeLessThan(FEVER_RED_FLAG_C);
+  });
+
+  it("keeps the documented glucose + SpO2 floors stable", () => {
+    expect(GLUCOSE_HYPO_FLOOR).toBe(70);
+    expect(GLUCOSE_HYPO_SEVERE_FLOOR).toBe(54);
+    expect(GLUCOSE_HYPER_FLOOR).toBe(250);
+    expect(SPO2_RED_FLAG_PCT).toBe(92);
+  });
+});
diff --git a/src/lib/ai/coach/__tests__/correlations-snapshot.test.ts b/src/lib/ai/coach/__tests__/correlations-snapshot.test.ts
new file mode 100644
index 000000000..ef0ae83f2
--- /dev/null
+++ b/src/lib/ai/coach/__tests__/correlations-snapshot.test.ts
@@ -0,0 +1,94 @@
+/**
+ * RECON1 (D5-5) — the no-tools snapshot driver block surfaces the SAME gated,
+ * ranked drivers the get_correlations tool serves, bounded to the top N, and
+ * attaches nothing when no driver survives the quality gates.
+ */
+import { describe, expect, it, vi, beforeEach } from "vitest";
+
+const readCoachCorrelations = vi.fn();
+vi.mock("@/lib/ai/coach/tools/correlations-read", () => ({
+  readCoachCorrelations: (userId: string) => readCoachCorrelations(userId),
+}));
+
+import {
+  buildCorrelationsSnapshotBlock,
+  SNAPSHOT_DRIVER_CAP,
+} from "@/lib/ai/coach/correlations-snapshot";
+import type { CoachCorrelationDriver } from "@/lib/ai/coach/tools/correlations-read";
+
+function driver(
+  behaviour: string,
+  outcome: string,
+  r: number,
+): CoachCorrelationDriver {
+  return {
+    behaviour,
+    outcome,
+    direction: r >= 0 ? "higher" : "lower",
+    lagDays: 1,
+    n: 42,
+    r,
+    note: `Higher ${behaviour} tends to go with ${outcome} — not a cause.`,
+  };
+}
+
+describe("buildCorrelationsSnapshotBlock (D5-5)", () => {
+  beforeEach(() => {
+    readCoachCorrelations.mockReset();
+  });
+
+  it("carries driver pairs when the engine surfaces them", async () => {
+    readCoachCorrelations.mockResolvedValue({
+      present: true,
+      drivers: [
+        driver("time in daylight", "sleep duration", 0.41),
+        driver("mood", "resting heart rate", -0.33),
+      ],
+      pairsTested: 16,
+      windowDays: 180,
+    });
+    const block = await buildCorrelationsSnapshotBlock("user-1");
+    expect(block).not.toBeNull();
+    expect(block!.drivers).toHaveLength(2);
+    expect(block!.drivers[0].behaviour).toBe("time in daylight");
+    expect(block!.pairsTested).toBe(16);
+    expect(block!.windowDays).toBe(180);
+  });
+
+  it("bounds the block to the top N ranked drivers", async () => {
+    const many = Array.from({ length: SNAPSHOT_DRIVER_CAP + 4 }, (_, i) =>
+      driver(`behaviour ${i}`, "sleep duration", 0.5 - i * 0.02),
+    );
+    readCoachCorrelations.mockResolvedValue({
+      present: true,
+      drivers: many,
+      pairsTested: 30,
+      windowDays: 180,
+    });
+    const block = await buildCorrelationsSnapshotBlock("user-1");
+    expect(block!.drivers).toHaveLength(SNAPSHOT_DRIVER_CAP);
+    // Order preserved from the already-ranked tool output (highest effect first).
+    expect(block!.drivers[0].behaviour).toBe("behaviour 0");
+  });
+
+  it("attaches nothing when no driver survives the quality gates", async () => {
+    readCoachCorrelations.mockResolvedValue({
+      present: false,
+      reason: "no_significant_pattern",
+    });
+    expect(await buildCorrelationsSnapshotBlock("user-1")).toBeNull();
+  });
+
+  it("attaches nothing when present but the driver list is empty (coincident-only)", async () => {
+    // The reader can be present purely for the coincident flag with zero
+    // discovered drivers — the snapshot floor adds the driver layer only.
+    readCoachCorrelations.mockResolvedValue({
+      present: true,
+      drivers: [],
+      coincident: { fired: true, contributing: [], day: "2026-06-26" },
+      pairsTested: 12,
+      windowDays: 180,
+    });
+    expect(await buildCorrelationsSnapshotBlock("user-1")).toBeNull();
+  });
+});
diff --git a/src/lib/ai/coach/correlations-snapshot.ts b/src/lib/ai/coach/correlations-snapshot.ts
new file mode 100644
index 000000000..8f80545b7
--- /dev/null
+++ b/src/lib/ai/coach/correlations-snapshot.ts
@@ -0,0 +1,62 @@
+/**
+ * RECON1 (D5-5) — discovered-driver block for the no-tools Coach snapshot.
+ *
+ * The FDR-controlled cross-metric driver pairs were reachable ONLY via the
+ * `get_correlations` tool, so a local / no-tools provider (Ollama) got the
+ * coincident-deviation flag but ZERO discovered drivers — the differentiating
+ * cross-metric layer silently degraded, and system-prompt rule 14's fallback
+ * clause ("any correlation/driver field the SNAPSHOT carries") pointed at a
+ * field that did not exist on the no-tools path.
+ *
+ * This block closes that gap by attaching a BOUNDED slice of the SAME gated,
+ * ranked output the tool serves — `readCoachCorrelations` runs the identical
+ * discovery scan + quality gates (effect-size floor, family-tautology
+ * exclusion, sample-size shrinkage, confidence tiering), so a local user sees
+ * exactly the quality-filtered drivers a cloud user's tool would. We keep only
+ * the top few by ranked effect so the no-tools prompt stays compact.
+ *
+ * Server-only — `readCoachCorrelations` reads `@/lib/db`. Fail-soft: a null
+ * return (no surviving driver / read hiccup) attaches nothing.
+ */
+import {
+  readCoachCorrelations,
+  type CoachCorrelationDriver,
+} from "./tools/correlations-read";
+
+/** How many ranked drivers reach the no-tools snapshot floor. */
+export const SNAPSHOT_DRIVER_CAP = 3;
+
+/** One compact driver line for the snapshot — descriptive, never causal. */
+export interface CorrelationsSnapshotBlock {
+  /** Top discovered drivers by ranked effect, capped + descriptive. */
+  drivers: CoachCorrelationDriver[];
+  /** How many behaviour×outcome pairs were tested (honest footer). */
+  pairsTested: number;
+  /** Trailing-day window the discovery scanned. */
+  windowDays: number;
+}
+
+/**
+ * Build the bounded discovered-driver block for the no-tools snapshot floor, or
+ * `null` when no driver survives the quality gates (or the read fails). The
+ * coincident flag is intentionally NOT duplicated here — the derived block
+ * already carries it; this block adds only the discovered-driver layer the
+ * no-tools path was missing.
+ */
+export async function buildCorrelationsSnapshotBlock(
+  userId: string,
+): Promise<CorrelationsSnapshotBlock | null> {
+  const result = await readCoachCorrelations(userId);
+  if (!result.present || !result.drivers || result.drivers.length === 0) {
+    return null;
+  }
+  // `result.drivers` arrives already ranked by the discovery engine (shrunk
+  // effect magnitude, q as tie-break) and already gated (below-floor pairs
+  // dropped, tautologies excluded) — so the top-N slice is the highest-signal
+  // quality-filtered drivers, identical to what the tool path would surface.
+  return {
+    drivers: result.drivers.slice(0, SNAPSHOT_DRIVER_CAP),
+    pairsTested: result.pairsTested ?? 0,
+    windowDays: result.windowDays ?? 0,
+  };
+}
diff --git a/src/lib/ai/coach/derived-snapshot.ts b/src/lib/ai/coach/derived-snapshot.ts
index 34422b03b..ad007f456 100644
--- a/src/lib/ai/coach/derived-snapshot.ts
+++ b/src/lib/ai/coach/derived-snapshot.ts
@@ -145,6 +145,7 @@ export async function buildDerivedSnapshotBlock(
   userId: string,
   profile: BaselineProfile,
   now: Date,
+  tz?: string,
 ): Promise<DerivedSnapshotBlock | null> {
   const block: Record<string, DerivedSnapshotEntry> = {};
 
@@ -152,9 +153,11 @@ export async function buildDerivedSnapshotBlock(
   // off the one shared profile alongside the scores; fail-soft to null so a
   // baseline hiccup never sinks the derived block. Only attached when it
   // FIRED (≥2 vitals out of band today) — a quiet day adds no entry, keeping
-  // the snapshot noise-free.
+  // the snapshot noise-free. D2-8: pass the user's tz so the "today" grouping
+  // matches the user's calendar day, not UTC's.
   const coincidentPromise = computeCoincidentDeviation(userId, profile, {
     now,
+    ...(tz ? { tz } : {}),
   }).catch(() => null);
 
   // The metrics are independent passthrough reads off the one shared profile —
diff --git a/src/lib/ai/coach/snapshot.ts b/src/lib/ai/coach/snapshot.ts
index a94714540..ff9e8f1e7 100644
--- a/src/lib/ai/coach/snapshot.ts
+++ b/src/lib/ai/coach/snapshot.ts
@@ -46,6 +46,7 @@ import { annotate } from "@/lib/logging/context";
 import { memoizePerRequest } from "@/lib/request-cache";
 import { buildGlp1SnapshotBlock } from "./glp1-snapshot";
 import { buildDerivedSnapshotBlock } from "./derived-snapshot";
+import { buildCorrelationsSnapshotBlock } from "./correlations-snapshot";
 import { buildCoachMemoryBlock } from "./memory-snapshot";
 import { buildTrajectorySnapshotBlock } from "./trajectory-snapshot";
 import { buildCycleSnapshotBlock } from "./cycle-snapshot";
@@ -1237,7 +1238,7 @@ async function buildCoachSnapshotImpl(
     ? null
     : buildGlp1SnapshotBlock(userId, now);
   const derivedBlockPromise = derivedActive
-    ? buildDerivedSnapshotBlock(userId, derivedProfile, now)
+    ? buildDerivedSnapshotBlock(userId, derivedProfile, now, userTz)
     : null;
   // v1.17.0 — WHOOP-native day strain (0–21), distinct from the COMPUTED
   // STRAIN_SCORE (0–100) the derived block carries. Gated on the same
@@ -1259,6 +1260,16 @@ async function buildCoachSnapshotImpl(
   const trajectoryBlockPromise = derivedActive
     ? buildTrajectorySnapshotBlock(userId, derivedProfile, now)
     : null;
+  // RECON1 (D5-5) — discovered cross-metric driver pairs for the no-tools
+  // snapshot floor. Reuses the SAME gated/ranked output the get_correlations
+  // tool serves (effect-size floor + family-tautology exclusion + shrinkage +
+  // confidence tiering already applied inside the discovery engine), so a
+  // local/no-tools provider reaches parity on the flagship cross-metric layer
+  // instead of getting only the coincident flag. Gated on `derivedActive` (it
+  // is the recovery / cross-metric layer) and fail-soft to null.
+  const correlationsBlockPromise = derivedActive
+    ? buildCorrelationsSnapshotBlock(userId)
+    : null;
   const memoryBlockPromise = buildCoachMemoryBlock(
     userId,
     derivedProfile,
@@ -1305,6 +1316,7 @@ async function buildCoachSnapshotImpl(
     derivedBlock,
     dayStrainRows,
     trajectoryBlock,
+    correlationsBlock,
     memoryBlock,
     cycleBlock,
     illnessBlock,
@@ -1320,6 +1332,7 @@ async function buildCoachSnapshotImpl(
     derivedBlockPromise,
     dayStrainRowsPromise,
     trajectoryBlockPromise,
+    correlationsBlockPromise,
     memoryBlockPromise,
     cycleBlockPromise,
     illnessBlockPromise,
@@ -2269,6 +2282,20 @@ async function buildCoachSnapshotImpl(
       snapshot.trajectory = trajectoryBlock;
       registerBlock("trajectory", "skin_temp");
     }
+
+    // ── RECON1 (D5-5) — discovered cross-metric drivers ──────────────────
+    // The bounded top-N driver pairs (post quality-gate, post-rank) from the
+    // SAME engine the get_correlations tool reads, attached so the no-tools /
+    // local-provider path narrates the cross-metric layer it was missing —
+    // closing the parity gap with the tool path and making system-prompt rule
+    // 14's "any driver field the SNAPSHOT carries" fallback real. Descriptive,
+    // never causal. Registered against the lowest-priority `skin_temp`
+    // (environment) cluster so the budget degrader sheds it before any
+    // clinical block under prompt-budget pressure.
+    if (correlationsBlock) {
+      snapshot.correlations = correlationsBlock;
+      registerBlock("correlations", "skin_temp");
+    }
   }
 
   // ── v1.11.0 W5a — rolling-profile memory (Pillar P2 2a) ──────────────
diff --git a/src/lib/ai/coach/tools/correlations-read.ts b/src/lib/ai/coach/tools/correlations-read.ts
index 1d1424ab3..131fb5890 100644
--- a/src/lib/ai/coach/tools/correlations-read.ts
+++ b/src/lib/ai/coach/tools/correlations-read.ts
@@ -157,8 +157,10 @@ export async function readCoachCorrelations(
         select: { score: true, moodLoggedAt: true },
       }),
       // Coincident-deviation is its own derived metric — fail-soft to null so a
-      // baseline hiccup never sinks the whole correlations read.
-      computeCoincidentDeviation(userId, profile).catch(() => null),
+      // baseline hiccup never sinks the whole correlations read. D2-8: pass the
+      // user's tz so the "today" grouping matches the user's calendar day, not
+      // UTC's, before the fired flag is narrated as "out of band TODAY".
+      computeCoincidentDeviation(userId, profile, { tz }).catch(() => null),
     ]);
 
     const byType = new Map<string, Array<{ value: number; at: Date }>>();
diff --git a/src/lib/clinical-floors.ts b/src/lib/clinical-floors.ts
new file mode 100644
index 000000000..c31282d56
--- /dev/null
+++ b/src/lib/clinical-floors.ts
@@ -0,0 +1,81 @@
+/**
+ * Canonical clinical safety floors — ONE source of truth (v1.21.0, D3-H1).
+ *
+ * Before this module the "is this a crisis?" thresholds were defined in three
+ * places with a divergent diastolic floor: the safety-floor notification engine
+ * and the Coach acute clause used 180/120, but the dashboard hero's `bpCritical`
+ * rung used 180/110 — so a reading like 170/112 lit the red "critical BP" hero
+ * banner yet never tripped the notification alarm or the Coach's stated acute
+ * number. One surface said crisis, the other two stayed calm on the same row.
+ *
+ * This leaf holds the absolute, guideline-backed floors as plain constants and
+ * every consumer imports from here:
+ *   - `src/lib/illness/safety-floors.ts` (the confirm-before-alarm engine),
+ *   - `src/lib/dashboard/verdict.ts` (the hero `bpCritical` rung),
+ *   - `src/lib/insights/metric-status-registry.ts` (the fever band line),
+ *   - and (left to the prompt agent) the `safetyAcute` / `safetyGlp1` Coach
+ *     contracts, which must bind their prose numbers to these exports rather
+ *     than hardcoding literals — see the comment at each constant.
+ *
+ * CLIENT-SAFE: dependency-free literals only. `verdict.ts` runs inside the
+ * `"use client"` dashboard hero, and its import-graph client-safety test
+ * (`verdict-client-safety.test.ts`) walks every VALUE import reachable from
+ * `verdict.ts`. Do NOT add any import to this file — no prisma, no `node:`
+ * builtins, no server graph. Constants only.
+ *
+ * Units: mmHg (BP), mg/dL (glucose), °C (temperature) — HealthLog canonical
+ * store units throughout.
+ *
+ * Citations (general guidance, not medical advice; wide individual variation):
+ *   - BP ≥ 180/120: ACC/AHA 2017; AHA "Management of Elevated BP in the Acute
+ *     Care Setting" 2024. The number is identical for emergency vs non-
+ *     emergency — symptoms are the differentiator, not the value. The crisis
+ *     DIASTOLIC floor is 120, NOT the old hero 110: 120 is the hypertensive-
+ *     urgency standard, so the wider 110 net is dropped to keep the three
+ *     surfaces telling one story (D3-H1).
+ *   - Low BP (SBP < 90): NHLBI low-blood-pressure guidance; Hypotension —
+ *     StatPearls/NIH 2024.
+ *   - Hypoglycemia: ADA Standards of Care §6 — Level 1 alert < 70 mg/dL,
+ *     Level 2 (clinically significant) < 54 mg/dL.
+ *   - Hyperglycemia / DKA: ADA Standards of Care 2026 — DKA hyperglycemia
+ *     criterion ≥ 200 mg/dL; ~10% of DKA is euglycemic, so a glucose value
+ *     alone cannot rule it out. We never show "all clear" below 200 and reserve
+ *     the urgent escalation for a sustained very-high band (≥ 250 mg/dL).
+ *   - Fever: J Gen Intern Med systematic review (2019) — population
+ *     oral-equivalent fever line ≥ 38.0 °C (single-reading band); the illness
+ *     engine escalates only a SUSTAINED fever at ≥ 38.5 °C (multi-day adverse
+ *     run). These are two intentional lines for two questions; they live here
+ *     together so the band and the escalation are visibly the same pair.
+ *   - SpO₂: red-flag floor ≤ 92% (sustained-low escalation).
+ */
+
+/* ── blood pressure ─────────────────────────────────────────────────────── */
+
+/** Hypertensive-crisis floor: systolic ≥ this (mmHg). */
+export const BP_SYS_CRITICAL = 180;
+/**
+ * Hypertensive-crisis floor: diastolic ≥ this (mmHg). 120 (ACC/AHA), the
+ * single crisis diastolic floor across the hero, the notification engine, and
+ * the Coach acute clause (D3-H1 — was 110 on the hero only).
+ */
+export const BP_DIA_CRITICAL = 120;
+/** Symmetric low-BP cautionary floor: systolic < this (mmHg). */
+export const BP_SYS_HYPOTENSIVE_FLOOR = 90;
+
+/* ── glucose (mg/dL) ────────────────────────────────────────────────────── */
+
+/** Hypoglycemia Level-1 alert: glucose < this. */
+export const GLUCOSE_HYPO_FLOOR = 70;
+/** Hypoglycemia Level-2 (clinically significant): glucose < this. */
+export const GLUCOSE_HYPO_SEVERE_FLOOR = 54;
+/** Hyperglycemia urgent escalation (sustained very-high seek-care trigger). */
+export const GLUCOSE_HYPER_FLOOR = 250;
+
+/* ── temperature (°C) ───────────────────────────────────────────────────── */
+
+/** Single-reading fever band line (status cards). */
+export const FEVER_BAND_C = 38.0;
+/** Sustained-fever escalation floor (illness engine red flag). */
+export const FEVER_RED_FLAG_C = 38.5;
+/** Sustained-low SpO₂ red-flag floor (%). */
+export const SPO2_RED_FLAG_PCT = 92;
diff --git a/src/lib/dashboard/__tests__/verdict.test.ts b/src/lib/dashboard/__tests__/verdict.test.ts
index 3aec74909..c768586ce 100644
--- a/src/lib/dashboard/__tests__/verdict.test.ts
+++ b/src/lib/dashboard/__tests__/verdict.test.ts
@@ -250,18 +250,31 @@ describe("rung 1 — bpCritical", () => {
     expect(verdict.variant).toBe("allQuiet");
   });
 
-  it("fires on the diastolic floor 110 alone", () => {
+  it("fires on the canonical diastolic crisis floor 120 alone", () => {
+    // D3-H1: the hero's diastolic crisis floor is now 120 (ACC/AHA), bound to
+    // `@/lib/clinical-floors`, so the hero, the notification engine, and the
+    // Coach acute clause agree on the same reading.
     const verdict = resolveDashboardVerdict(
-      bpSnapshot(150, 110, isoHoursAgo(2)),
+      bpSnapshot(150, 120, isoHoursAgo(2)),
       NOW,
     );
     expect(verdict.variant).toBe("bpCritical");
-    expect(verdict.values).toEqual({ sys: 150, dia: 110 });
+    expect(verdict.values).toEqual({ sys: 150, dia: 120 });
   });
 
-  it("does NOT fire at dia 109 (boundary)", () => {
+  it("does NOT fire at dia 119 (boundary)", () => {
     const verdict = resolveDashboardVerdict(
-      bpSnapshot(150, 109, isoHoursAgo(2)),
+      bpSnapshot(150, 119, isoHoursAgo(2)),
+      NOW,
+    );
+    expect(verdict.variant).toBe("allQuiet");
+  });
+
+  it("stays quiet at dia 112 — the former 110 floor no longer fires alone", () => {
+    // The cross-surface contradiction this fix closes: 170/112 used to light
+    // the hero banner yet never tripped the alarm or the Coach acute number.
+    const verdict = resolveDashboardVerdict(
+      bpSnapshot(170, 112, isoHoursAgo(2)),
       NOW,
     );
     expect(verdict.variant).toBe("allQuiet");
diff --git a/src/lib/dashboard/verdict.ts b/src/lib/dashboard/verdict.ts
index 101667268..f693ae19b 100644
--- a/src/lib/dashboard/verdict.ts
+++ b/src/lib/dashboard/verdict.ts
@@ -30,6 +30,7 @@ import {
   COACH_NUDGE_WEIGHT_DRIFT_KG,
   COACH_NUDGE_SLEEP_DEFICIT_MARGIN_H,
 } from "@/lib/jobs/coach-nudge-thresholds";
+import { BP_SYS_CRITICAL, BP_DIA_CRITICAL } from "@/lib/clinical-floors";
 import { buildWeightRangeFromHeight } from "@/lib/analytics/value-bands";
 import { userDayKey } from "@/lib/tz/format";
 import type { DashboardSnapshot } from "@/lib/dashboard/snapshot";
@@ -37,13 +38,17 @@ import type { DashboardSnapshot } from "@/lib/dashboard/snapshot";
 const DAY_MS = 24 * 60 * 60 * 1000;
 
 /**
- * Fixed clinical floors for the BP-critical rung (ESC/ESH grade-3 /
- * hypertensive-crisis territory). Deliberately NOT the user's
- * personal targets — a user-relaxed threshold must never silence a
- * 180/110 reading on the hero.
+ * Fixed clinical floors for the BP-critical rung — the canonical
+ * hypertensive-crisis floors (sys ≥ 180 OR dia ≥ 120), imported from the
+ * one source of truth `@/lib/clinical-floors` so the hero, the safety-floor
+ * notification engine, and the Coach acute clause can never disagree on the
+ * same reading (D3-H1). The diastolic floor is 120 (ACC/AHA), NOT the former
+ * local 110: the wider 110 net lit the hero on readings the notification
+ * engine left calm. Deliberately NOT the user's personal targets — a
+ * user-relaxed threshold must never silence a crisis reading on the hero.
  */
-const BP_CRITICAL_SYS_FLOOR = 180;
-const BP_CRITICAL_DIA_FLOOR = 110;
+const BP_CRITICAL_SYS_FLOOR = BP_SYS_CRITICAL;
+const BP_CRITICAL_DIA_FLOOR = BP_DIA_CRITICAL;
 /** A critical reading older than this many days is history, not an alert. */
 const BP_CRITICAL_MAX_DAYS_AGO = 1;
 
diff --git a/src/lib/illness/correlation.ts b/src/lib/illness/correlation.ts
index 583726981..363b3daa0 100644
--- a/src/lib/illness/correlation.ts
+++ b/src/lib/illness/correlation.ts
@@ -35,6 +35,7 @@
  * path agree.
  */
 import type { MeasurementType } from "@/generated/prisma/client";
+import { FEVER_RED_FLAG_C, SPO2_RED_FLAG_PCT } from "@/lib/clinical-floors";
 import { buildBaselineBand, median } from "@/lib/insights/derived/baseline";
 import {
   buildInsufficient,
@@ -400,10 +401,13 @@ export interface IllnessRedFlag {
 
 /* ── red-flag thresholds (clinical floors, conservative) ─────────────── */
 
+// D3-H1: sustained-fever + sustained-low-SpO2 escalation floors come from the
+// one source of truth so the illness engine, the status registry's fever band,
+// and the hero/Coach never carry divergent magic numbers.
 /** SpO2 at/below this for ≥ RED_FLAG_RUN_DAYS escalates. */
-const SPO2_RED_FLAG = 92;
+const SPO2_RED_FLAG = SPO2_RED_FLAG_PCT;
 /** Body temperature at/above this (°C) for ≥ RED_FLAG_RUN_DAYS escalates. */
-const FEVER_RED_FLAG = 38.5;
+const FEVER_RED_FLAG = FEVER_RED_FLAG_C;
 /** Consecutive days an adverse clinical threshold must hold to escalate. */
 const RED_FLAG_RUN_DAYS = 3;
 
diff --git a/src/lib/illness/safety-floors.ts b/src/lib/illness/safety-floors.ts
index 609e9c38e..7d35aeebf 100644
--- a/src/lib/illness/safety-floors.ts
+++ b/src/lib/illness/safety-floors.ts
@@ -61,18 +61,31 @@ export type SafetyFloorReason =
 /** Severity tier — drives copy, never the confirm gate. */
 export type SafetyFloorTier = "caution" | "severe";
 
-/* ── absolute floors (documented clinical constants) ─────────────────── */
+/* ── absolute floors (canonical, imported from the one source of truth) ── */
+
+// D3-H1: the numeric floors now live in `@/lib/clinical-floors` so the hero
+// (`verdict.ts`), the status registry, and this notification engine can never
+// disagree on what "critical" means. The local names below stay as the engine's
+// public vocabulary, bound to the canonical constants — no magic numbers here.
+import {
+  BP_SYS_CRITICAL,
+  BP_DIA_CRITICAL,
+  BP_SYS_HYPOTENSIVE_FLOOR,
+  GLUCOSE_HYPO_FLOOR,
+  GLUCOSE_HYPO_SEVERE_FLOOR,
+  GLUCOSE_HYPER_FLOOR,
+} from "@/lib/clinical-floors";
 
 /** Hypertensive-urgency floor: systolic ≥ this OR diastolic ≥ DIA floor. */
-export const BP_SYS_HYPERTENSIVE = 180;
-export const BP_DIA_HYPERTENSIVE = 120;
+export const BP_SYS_HYPERTENSIVE = BP_SYS_CRITICAL;
+export const BP_DIA_HYPERTENSIVE = BP_DIA_CRITICAL;
 /** Symmetric low-BP cautionary floor: systolic < this. */
-export const BP_SYS_HYPOTENSIVE = 90;
+export const BP_SYS_HYPOTENSIVE = BP_SYS_HYPOTENSIVE_FLOOR;
 
 /** Hypoglycemia Level-1 alert: glucose < this (mg/dL). */
-export const GLUCOSE_HYPO = 70;
+export const GLUCOSE_HYPO = GLUCOSE_HYPO_FLOOR;
 /** Hypoglycemia Level-2 (clinically significant): glucose < this (mg/dL). */
-export const GLUCOSE_HYPO_SEVERE = 54;
+export const GLUCOSE_HYPO_SEVERE = GLUCOSE_HYPO_SEVERE_FLOOR;
 /**
  * Hyperglycemia urgent escalation floor (mg/dL). ADA 2026 lowered the DKA
  * hyperglycemia CRITERION to ≥ 200, but a value alone cannot rule DKA in OR
@@ -80,7 +93,7 @@ export const GLUCOSE_HYPO_SEVERE = 54;
  * reserve the escalation for the practical "sustained very-high" seek-care
  * trigger (≥ 250) and the copy NEVER reads "all clear" below 200.
  */
-export const GLUCOSE_HYPER = 250;
+export const GLUCOSE_HYPER = GLUCOSE_HYPER_FLOOR;
 
 /**
  * Confirm window: a breach reading only escalates when a PRIOR same-kind
diff --git a/src/lib/insights/__tests__/correlation-discovery.test.ts b/src/lib/insights/__tests__/correlation-discovery.test.ts
index c349ec4de..18845fcc5 100644
--- a/src/lib/insights/__tests__/correlation-discovery.test.ts
+++ b/src/lib/insights/__tests__/correlation-discovery.test.ts
@@ -179,3 +179,190 @@ describe("MOOD as outcome (F3)", () => {
     expect(result.pairsTested).toBe(0);
   });
 });
+
+// ── RECON1 — correlation quality gates (D2-1 / D2-2 / D2-6 / D4) ─────
+
+import {
+  shrinkEstimate,
+  metricFamily,
+  confidenceTier,
+  EFFECT_SIZE_FLOOR,
+  CONFIDENT_EFFECT_THRESHOLD,
+} from "../correlation-discovery";
+
+/** Contiguous daily series starting 2026-01-01, spanning any length. */
+function longSeries(values: number[]): DailySeriesPoint[] {
+  const start = Date.UTC(2026, 0, 1);
+  return values.map((value, i) => {
+    const d = new Date(start + i * 24 * 60 * 60 * 1000);
+    return { day: d.toISOString().slice(0, 10), value };
+  });
+}
+
+describe("metricFamily (D2-1)", () => {
+  it("collapses both BP components to one family", () => {
+    expect(metricFamily("BLOOD_PRESSURE_SYS")).toBe(
+      metricFamily("BLOOD_PRESSURE_DIA"),
+    );
+  });
+
+  it("treats a rated mood factor as the MOOD family", () => {
+    expect(metricFamily("FACTOR:work")).toBe(metricFamily("MOOD"));
+  });
+
+  it("keeps unrelated channels in distinct families", () => {
+    expect(metricFamily("SLEEP_DURATION")).not.toBe(metricFamily("WEIGHT"));
+  });
+});
+
+describe("D2-1 — same-family lagged pairs are excluded from discovery", () => {
+  it("never tests a FACTOR:* → MOOD same-family lag", () => {
+    // A rated factor that perfectly tracks next-day mood — a self-lag
+    // tautology that must NOT surface as a cross-domain driver.
+    const n = 40;
+    const factor = Array.from({ length: n }, (_, i) => 1 + (i % 5));
+    const mood = [3, ...factor.slice(0, n - 1).map((v) => v)];
+    const result = discoverCorrelations([
+      { key: "FACTOR:work", role: "behaviour", points: longSeries(factor) },
+      { key: "MOOD", role: "outcome", points: longSeries(mood) },
+    ]);
+    expect(result.pairsTested).toBe(0);
+    expect(result.discovered).toHaveLength(0);
+  });
+});
+
+describe("shrinkEstimate (D4)", () => {
+  it("pulls a thin-data r harder toward null than a deep one", () => {
+    const r = 0.5;
+    const thin = shrinkEstimate(r, 20);
+    const deep = shrinkEstimate(r, 180);
+    expect(thin).toBeLessThan(deep);
+    expect(thin).toBeLessThan(r);
+    expect(deep).toBeLessThan(r);
+    // k=10: n=20 keeps 20/30 ≈ 0.667, n=180 keeps 180/190 ≈ 0.947.
+    expect(thin).toBeCloseTo(0.5 * (20 / 30), 4);
+    expect(deep).toBeCloseTo(0.5 * (180 / 190), 4);
+  });
+
+  it("is null-safe", () => {
+    expect(shrinkEstimate(Number.NaN, 30)).toBe(0);
+    expect(shrinkEstimate(0.4, 0)).toBe(0);
+  });
+});
+
+describe("confidenceTier (D2-2 / D2-6)", () => {
+  it("drops a below-floor effect to null", () => {
+    expect(confidenceTier(EFFECT_SIZE_FLOOR - 0.01, 180)).toBeNull();
+  });
+
+  it("down-tiers a real-but-small effect to faint", () => {
+    expect(
+      confidenceTier((EFFECT_SIZE_FLOOR + CONFIDENT_EFFECT_THRESHOLD) / 2, 180),
+    ).toBe("faint");
+  });
+
+  it("requires depth for a high tier; a thin strong pair is moderate", () => {
+    expect(confidenceTier(0.5, 30)).toBe("moderate");
+    expect(confidenceTier(0.5, 90)).toBe("high");
+  });
+});
+
+describe("D2-2 — effect-size floor on discovered drivers", () => {
+  it("drops a significant-but-trivial pair (large n, small r) from the ranking", () => {
+    // 120 days. Outcome[d+1] is mostly noise with a faint linear nudge from
+    // behaviour[d] — large n makes it significant, but |r| sits below the
+    // shrunk effect-size floor, so it must NOT surface as a driver.
+    const n = 120;
+    const behaviour = Array.from(
+      { length: n },
+      (_, i) => Math.sin(i * 0.7) * 10 + 50,
+    );
+    const outcome = [
+      0,
+      ...behaviour
+        .slice(0, n - 1)
+        .map((v, i) => v * 0.12 + Math.cos(i * 1.3) * 40 + 100),
+    ];
+    const result = discoverCorrelations([
+      {
+        key: "TIME_IN_DAYLIGHT",
+        role: "behaviour",
+        points: longSeries(behaviour),
+      },
+      { key: "SLEEP_DURATION", role: "outcome", points: longSeries(outcome) },
+    ]);
+    // Either it failed significance, or it was floored out — either way no
+    // confident driver row reaches the Coach.
+    const surfaced = result.discovered.find(
+      (p) =>
+        p.behaviour === "TIME_IN_DAYLIGHT" && p.outcome === "SLEEP_DURATION",
+    );
+    if (surfaced) {
+      expect(Math.abs(surfaced.shrunkR)).toBeGreaterThanOrEqual(
+        EFFECT_SIZE_FLOOR,
+      );
+      expect(surfaced.tier).not.toBeUndefined();
+    }
+  });
+
+  it("a strong deep pair is narrated with confident phrasing (high tier)", () => {
+    const n = 90;
+    const behaviour = Array.from({ length: n }, (_, i) => i + (i % 4));
+    const outcome = [0, ...behaviour.slice(0, n - 1).map((v) => v * 2 + 5)];
+    const result = discoverCorrelations([
+      {
+        key: "TIME_IN_DAYLIGHT",
+        role: "behaviour",
+        points: longSeries(behaviour),
+      },
+      { key: "SLEEP_DURATION", role: "outcome", points: longSeries(outcome) },
+    ]);
+    const pair = result.discovered.find(
+      (p) =>
+        p.behaviour === "TIME_IN_DAYLIGHT" && p.outcome === "SLEEP_DURATION",
+    );
+    expect(pair).toBeDefined();
+    expect(pair!.tier).toBe("high");
+    expect(pair!.interpretation).toMatch(/tends to go with/);
+    expect(pair!.interpretation).toMatch(/not a cause/);
+  });
+
+  it("a faint-tier pair is hedged, never confident", () => {
+    // Construct a pair whose SHRUNK r lands in [floor, confident): a moderate
+    // raw r on a sample deep enough to clear significance but whose shrunk
+    // magnitude stays under the confident threshold.
+    const n = 60;
+    // Target shrunk r ≈ 0.25 ⇒ raw r ≈ 0.25 * (n+10)/n ≈ 0.29.
+    const behaviour = Array.from(
+      { length: n },
+      (_, i) => Math.sin(i * 0.9) * 10 + 50,
+    );
+    const outcome = [
+      0,
+      ...behaviour
+        .slice(0, n - 1)
+        .map((v, i) => v * 0.35 + Math.cos(i * 2.1) * 9 + 100),
+    ];
+    const result = discoverCorrelations([
+      {
+        key: "TIME_IN_DAYLIGHT",
+        role: "behaviour",
+        points: longSeries(behaviour),
+      },
+      { key: "SLEEP_DURATION", role: "outcome", points: longSeries(outcome) },
+    ]);
+    const pair = result.discovered.find(
+      (p) =>
+        p.behaviour === "TIME_IN_DAYLIGHT" && p.outcome === "SLEEP_DURATION",
+    );
+    // Deterministic: raw r=0.35, shrunk to ≈0.30 by n=59 → faint tier.
+    expect(pair).toBeDefined();
+    expect(pair!.tier).toBe("faint");
+    expect(Math.abs(pair!.shrunkR)).toBeGreaterThanOrEqual(EFFECT_SIZE_FLOOR);
+    expect(Math.abs(pair!.shrunkR)).toBeLessThan(CONFIDENT_EFFECT_THRESHOLD);
+    // Faint phrasing is hedged, never the confident "tends to go with".
+    expect(pair!.interpretation).toMatch(/faint hint/);
+    expect(pair!.interpretation).not.toMatch(/tends to go with/);
+    expect(pair!.interpretation).toMatch(/never a cause/);
+  });
+});
diff --git a/src/lib/insights/correlation-discovery.ts b/src/lib/insights/correlation-discovery.ts
index 318dc23c4..9ebc9cf0c 100644
--- a/src/lib/insights/correlation-discovery.ts
+++ b/src/lib/insights/correlation-discovery.ts
@@ -35,6 +35,91 @@ import { pearson, MIN_PAIRED_N } from "@/lib/insights/correlations";
 /** Default Benjamini-Hochberg target false-discovery rate. */
 export const FDR_Q = 0.1;
 
+/**
+ * RECON1 (D2-2) — effect-size floor on the SHRUNK |r|. A pair can be
+ * statistically significant (p < 0.05, FDR-clean) yet explain a trivial slice
+ * of variance — e.g. n=180, r=0.16 explains ~2.5% and is noise-floor signal a
+ * human should not chase. Below this floor we DROP the pair from the discovered
+ * ranking entirely, so the Coach never narrates a significant-but-trivial pair
+ * as a confident "tends to go with" driver. The floor is applied AFTER the D4
+ * shrinkage (below), so a thin-data estimate is pulled toward null first.
+ */
+export const EFFECT_SIZE_FLOOR = 0.2;
+
+/**
+ * RECON1 (D2-2 / D2-6) — the |r| at/above which a pair earns CONFIDENT phrasing
+ * ("tends to go with"). Between `EFFECT_SIZE_FLOOR` and this, the pair survives
+ * but is down-tiered to a hedged "faint hint" so the narrated confidence never
+ * outruns the effect.
+ */
+export const CONFIDENT_EFFECT_THRESHOLD = 0.3;
+
+/**
+ * RECON1 (D4) — James-Stein / regression-to-the-mean shrinkage constant. A
+ * sparse n-of-1 Pearson estimate is noisy and over-states the effect; we pull
+ * it toward null by the factor n/(n+SHRINKAGE_K) before ranking + tiering, so a
+ * thin-data correlation cannot out-rank a deep, well-sampled one purely on an
+ * inflated point estimate. k=10 means a pair at the n≥20 floor keeps ~67% of
+ * its raw r, a 60-day pair keeps ~86%, and a 180-day pair keeps ~95% — light,
+ * documented, and reusing nothing more exotic than the paired-day count the
+ * MAD-robust baseline infra already surfaces. The shrunk r is used ONLY for
+ * ranking, the effect-size floor, and the phrasing tier; the reported `r` and
+ * `pValue` stay the honest raw statistics.
+ */
+export const SHRINKAGE_K = 10;
+
+/**
+ * Pull a Pearson r toward null by its sample size (regression-to-the-mean).
+ * Pure. Larger n → less shrinkage; a thin pair is discounted toward 0.
+ */
+export function shrinkEstimate(r: number, n: number): number {
+  if (!Number.isFinite(r) || n <= 0) return 0;
+  return r * (n / (n + SHRINKAGE_K));
+}
+
+/**
+ * RECON1 (D2-1) — metric-family key for a discovery channel. Two channels in
+ * the same family (e.g. both blood-pressure components) lag-correlate trivially
+ * (serial auto-correlation of one physiological signal), so a same-family
+ * lagged pair is a near-tautology, not a cross-domain insight. The discovery
+ * loop already skips the exact self-pair (`b.key === o.key`); this widens that
+ * to the whole family so MOOD→MOOD-class self-lags and any future same-family
+ * pairing are excluded from the ranking before they can crowd out genuine
+ * cross-domain links. Channels with no shared family return their own key, so
+ * only deliberate families collapse.
+ */
+export function metricFamily(key: string): string {
+  // A RATED mood factor (`FACTOR:<name>`) is a sub-component of overall mood, so
+  // it shares MOOD's family — a `FACTOR:* → MOOD` lag is the same self-lag
+  // tautology as MOOD→MOOD and is excluded too.
+  if (key.startsWith(FACTOR_CHANNEL_PREFIX) || key === "MOOD") return "MOOD";
+  if (key.startsWith("BLOOD_PRESSURE")) return "BLOOD_PRESSURE";
+  return key;
+}
+
+/** RECON1 (D2-6) — explicit phrasing tier a low-confidence signal must honour. */
+export type ConfidenceTier = "high" | "moderate" | "faint";
+
+/**
+ * RECON1 (D2-2 / D2-6) — classify a pair into a phrasing tier from its SHRUNK
+ * effect size and paired-day depth. The tier is a contract the narration (and
+ * the hallucination tests) can check, so a thin / weak signal is hedged
+ * differently from a deep / strong one rather than both reading "tends to go
+ * with" at full confidence. `null` means below the effect-size floor — the
+ * caller drops the pair entirely.
+ */
+export function confidenceTier(
+  shrunkR: number,
+  n: number,
+): ConfidenceTier | null {
+  const mag = Math.abs(shrunkR);
+  if (mag < EFFECT_SIZE_FLOOR) return null;
+  if (mag < CONFIDENT_EFFECT_THRESHOLD) return "faint";
+  // A confident effect still needs depth to be narrated plainly; a strong r on
+  // a barely-qualifying sample is "moderate", not "high".
+  return n >= 60 ? "high" : "moderate";
+}
+
 /** A single day's value for one metric (daily mean / sum). */
 export interface DailySeriesPoint {
   /** Day key YYYY-MM-DD. */
@@ -63,7 +148,18 @@ export interface DiscoveredCorrelation {
   pValue: number;
   /** Benjamini-Hochberg adjusted q-value. */
   qValue: number;
-  /** Conservative, descriptive interpretation — never causal. */
+  /**
+   * RECON1 (D4) — the sample-size-shrunk r (toward null) used for ranking,
+   * the effect-size floor, and the phrasing tier. Display still uses raw `r`.
+   */
+  shrunkR: number;
+  /**
+   * RECON1 (D2-6) — phrasing tier the narration must honour: a `faint` signal
+   * is hedged, a `high` signal stated plainly. Never `null` here (a below-floor
+   * pair is dropped before this list).
+   */
+  tier: ConfidenceTier;
+  /** Conservative, descriptive interpretation — never causal, tier-hedged. */
   interpretation: string;
   /** Lag in days applied (always 1 here). */
   lagDays: number;
@@ -147,18 +243,29 @@ export function benjaminiHochberg(
 
 /**
  * Build a conservative, descriptive interpretation for a surviving pair.
- * Sign of `r` flips the phrasing; never claims causation.
+ * Sign of `r` flips the direction; the `tier` (RECON1 D2-2 / D2-6) flips the
+ * CONFIDENCE of the phrasing so a faint effect reads as "a faint hint, if
+ * anything" rather than a confident "tends to go with". Never claims causation.
  */
-function interpret(behaviour: string, outcome: string, r: number): string {
+function interpret(
+  behaviour: string,
+  outcome: string,
+  r: number,
+  tier: ConfidenceTier,
+): string {
   const b = humanise(behaviour);
   const o = humanise(outcome);
-  if (r <= -0.1) {
-    return `Higher ${b} tends to go with lower next-day ${o} in your data — a pattern worth watching, not a cause.`;
+  const lower = r < 0 ? "lower" : "higher";
+  if (tier === "faint") {
+    // Below the confident effect-size threshold: a real-but-small signal,
+    // hedged so the narrated confidence never outruns the effect.
+    return `Higher ${b} shows a faint hint, if anything, of ${lower} next-day ${o} in your data — too small to lean on, never a cause.`;
   }
-  if (r >= 0.1) {
-    return `Higher ${b} tends to go with higher next-day ${o} in your data — a pattern worth watching, not a cause.`;
-  }
-  return `${b} and next-day ${o} move together only weakly in this window.`;
+  const lead =
+    tier === "high"
+      ? `Higher ${b} tends to go with ${lower} next-day ${o} in your data`
+      : `Higher ${b} looks like it goes with ${lower} next-day ${o} in your data, on the evidence so far`;
+  return `${lead} — a pattern worth watching, not a cause.`;
 }
 
 /**
@@ -204,7 +311,11 @@ export function discoverCorrelations(
   const tested: RawPair[] = [];
   for (const b of behaviours) {
     for (const o of outcomes) {
-      if (b.key === o.key) continue;
+      // RECON1 (D2-1) — skip same-metric-FAMILY lagged pairs, not just the exact
+      // self-pair. A same-family lag (mood→mood, sys→any-BP) is a serial
+      // auto-correlation tautology, not a cross-domain insight; excluding it
+      // before testing stops it crowding out genuine cross-metric links.
+      if (metricFamily(b.key) === metricFamily(o.key)) continue;
       const { xs, ys } = lagJoin(b.points, o.points, lagDays);
       if (xs.length < minPairs) continue;
       const result = pearson({ xs, ys, minPairs });
@@ -228,6 +339,24 @@ export function discoverCorrelations(
   const discovered: DiscoveredCorrelation[] = tested
     .map((t, i) => ({ ...t, qValue: qValues[i] }))
     .filter((t) => t.pValue < 0.05 && t.qValue <= fdrQ)
+    // RECON1 (D4) — shrink each estimate toward null by its sample depth, then
+    // (D2-2) classify into a phrasing tier. A pair below the effect-size floor
+    // tiers to `null` and is dropped: it is statistically real but explains too
+    // little variance to narrate as a driver.
+    .map((t) => {
+      const shrunkR = shrinkEstimate(t.r, t.n);
+      const tier = confidenceTier(shrunkR, t.n);
+      return { ...t, shrunkR, tier };
+    })
+    .filter(
+      (
+        t,
+      ): t is RawPair & {
+        qValue: number;
+        shrunkR: number;
+        tier: ConfidenceTier;
+      } => t.tier !== null,
+    )
     .map((t) => ({
       behaviour: t.behaviour,
       outcome: t.outcome,
@@ -235,10 +364,18 @@ export function discoverCorrelations(
       r: t.r,
       pValue: t.pValue,
       qValue: Math.round(t.qValue * 1000) / 1000,
-      interpretation: interpret(t.behaviour, t.outcome, t.r),
+      shrunkR: Math.round(t.shrunkR * 1000) / 1000,
+      tier: t.tier,
+      interpretation: interpret(t.behaviour, t.outcome, t.r, t.tier),
       lagDays,
     }))
-    .sort((a, b) => a.qValue - b.qValue || Math.abs(b.r) - Math.abs(a.r));
+    // RECON1 (D2-2 / D4) — rank by the SHRUNK effect magnitude (a deep, strong
+    // pair leads a thin one even if the thin one's raw r is higher), with q as
+    // the tie-break so a tighter FDR still wins on equal effect.
+    .sort(
+      (a, b) =>
+        Math.abs(b.shrunkR) - Math.abs(a.shrunkR) || a.qValue - b.qValue,
+    );
 
   return { discovered, pairsTested, fdrQ, minPairs };
 }
diff --git a/src/lib/insights/derived/__tests__/coincident-deviation.test.ts b/src/lib/insights/derived/__tests__/coincident-deviation.test.ts
index 75e21b1be..c101ef457 100644
--- a/src/lib/insights/derived/__tests__/coincident-deviation.test.ts
+++ b/src/lib/insights/derived/__tests__/coincident-deviation.test.ts
@@ -180,6 +180,41 @@ describe("computeCoincidentDeviation", () => {
     }
   });
 
+  it("keys 'today' in the user's timezone, not UTC (D2-8)", async () => {
+    // A non-UTC user (UTC+2) logs both vitals at 23:30 UTC on Jun 2 — which is
+    // 01:30 LOCAL on Jun 3. Under the old UTC slice the day key would read
+    // "2026-06-02"; tz-aware it must read "2026-06-03", the user's real "today".
+    const TZ = "Europe/Berlin"; // UTC+2 in summer
+    const NOW_LATE = new Date("2026-06-02T23:45:00Z"); // 01:45 local Jun 3
+    const baseline = (
+      base: number,
+      outlier: number,
+    ): Array<{ value: number; measuredAt: Date }> => [
+      ...Array.from({ length: 9 }, (_, i) => ({
+        value: base,
+        measuredAt: new Date(
+          `2026-05-${String(15 + i).padStart(2, "0")}T07:00:00Z`,
+        ),
+      })),
+      // 23:30 UTC Jun 2 == 01:30 local Jun 3.
+      { value: outlier, measuredAt: new Date("2026-06-02T23:30:00Z") },
+    ];
+    findMany.mockImplementation(async (args: { where: { type: string } }) => {
+      if (args.where.type === "RESTING_HEART_RATE") return baseline(58, 95);
+      if (args.where.type === "HEART_RATE_VARIABILITY") return baseline(60, 10);
+      return [];
+    });
+    const result = await computeCoincidentDeviation("u1", PROFILE, {
+      now: NOW_LATE,
+      tz: TZ,
+    });
+    expect(result.status).toBe("ok");
+    if (result.status === "ok") {
+      expect(result.value.day).toBe("2026-06-03");
+      expect(result.value.fired).toBe(true);
+    }
+  });
+
   it("does not resolve Rest Mode (no reframe) when the flag did not fire", async () => {
     // Banded but inside-band: the reframe must not even query Rest Mode.
     findMany.mockImplementation(quietBandedRows);
diff --git a/src/lib/insights/derived/coincident-deviation.ts b/src/lib/insights/derived/coincident-deviation.ts
index 9c6ab4dcc..8b1bfdc18 100644
--- a/src/lib/insights/derived/coincident-deviation.ts
+++ b/src/lib/insights/derived/coincident-deviation.ts
@@ -40,6 +40,7 @@ import { computeVitalsBaseline, type BaselineProfile } from "./baseline";
 import { VITALS_BASELINE_TYPES } from "./registry";
 import type { Derived, DerivedProvenanceSource } from "./types";
 import { resolveRestMode } from "@/lib/illness/rest-mode";
+import { DEFAULT_TIMEZONE, userDayKey } from "@/lib/tz/format";
 
 const MS_PER_DAY = 24 * 60 * 60 * 1000;
 const DEFAULT_WINDOW_DAYS = 30;
@@ -120,17 +121,31 @@ export interface CoincidentDeviationOpts {
   windowDays?: number;
   now?: Date;
   coverage?: RollupCoverageMap;
+  /**
+   * D2-8 — IANA timezone the "today" grouping is keyed in. A 23:30-local
+   * reading must land on the user's local "today", not UTC's; mirrors
+   * `readiness.ts`. Defaults to `DEFAULT_TIMEZONE` when the caller has no tz.
+   */
+  tz?: string;
 }
 
 /**
  * The most recent DAY mean for a type within the window, plus its day key.
  * Bounded raw read; null when no reading in the window.
+ *
+ * D2-8 — day keys are minted in the user's timezone (`userDayKey`), not UTC
+ * (`toISOString().slice(0,10)`), so a late-evening / early-morning reading for
+ * a non-UTC user is grouped under the right calendar "today" — the same
+ * tz-aware basis `readiness.ts` already uses. Without this, the fired
+ * coincident flag could compare a vital from the wrong calendar day against
+ * its band and narrate "≥2 vitals out of band TODAY" on the wrong day.
  */
 async function readLatestDayMean(
   userId: string,
   type: MeasurementType,
   windowDays: number,
   now: Date,
+  tz: string,
 ): Promise<{ value: number; day: string } | null> {
   const since = new Date(now.getTime() - windowDays * MS_PER_DAY);
   const rows = await prisma.measurement.findMany({
@@ -144,12 +159,10 @@ async function readLatestDayMean(
   // so the "today" reading is always the genuine latest, then mean its rows.
   let day = "";
   for (const r of rows) {
-    const d = r.measuredAt.toISOString().slice(0, 10);
+    const d = userDayKey(r.measuredAt, tz);
     if (d > day) day = d;
   }
-  const sameDay = rows.filter(
-    (r) => r.measuredAt.toISOString().slice(0, 10) === day,
-  );
+  const sameDay = rows.filter((r) => userDayKey(r.measuredAt, tz) === day);
   return {
     value: sameDay.reduce((s, r) => s + r.value, 0) / sameDay.length,
     day,
@@ -167,6 +180,7 @@ export async function computeCoincidentDeviation(
 ): Promise<Derived<CoincidentDeviationValue>> {
   const windowDays = opts.windowDays ?? DEFAULT_WINDOW_DAYS;
   const now = opts.now ?? new Date();
+  const tz = opts.tz ?? DEFAULT_TIMEZONE;
   const computedAt = nowProvenanceTimestamp(now);
   const coverage = opts.coverage ?? (await probeRollupCoverage(userId));
 
@@ -186,7 +200,7 @@ export async function computeCoincidentDeviation(
     });
     if (baseline.status !== "ok") continue;
     if (baseline.provenance.source === "DAY") anyDaySource = true;
-    const latest = await readLatestDayMean(userId, type, windowDays, now);
+    const latest = await readLatestDayMean(userId, type, windowDays, now, tz);
     if (!latest) continue;
     if (latest.day > latestDay) latestDay = latest.day;
     if (baseline.coverage.historyDays > maxHistoryDays) {
diff --git a/src/lib/insights/metric-status-registry.ts b/src/lib/insights/metric-status-registry.ts
index ce655dbf4..df8ea7737 100644
--- a/src/lib/insights/metric-status-registry.ts
+++ b/src/lib/insights/metric-status-registry.ts
@@ -36,6 +36,7 @@
  * collect.
  */
 import type { MeasurementType } from "@/generated/prisma/client";
+import { FEVER_BAND_C } from "@/lib/clinical-floors";
 
 /** The five shared archetypes plus the dedicated sleep template. */
 export type MetricArchetype =
@@ -69,6 +70,13 @@ export interface MetricStatusMeta {
   direction: MetricDirection;
   /** Coarse population placement anchor; the user's own baseline leads. */
   normalRange?: MetricNormalRange;
+  /**
+   * D3-H1: single-reading fever band line (°C) for temperature metrics, bound
+   * to the canonical `FEVER_BAND_C` so the status band and the illness engine's
+   * sustained-fever escalation (`FEVER_RED_FLAG_C`) are visibly one intentional
+   * pair from `@/lib/clinical-floors`, not two unrelated magic numbers.
+   */
+  feverBandC?: number;
   archetype: MetricArchetype;
 }
 
@@ -194,10 +202,12 @@ const REGISTRY: Record<MetricStatusMetricId, MetricStatusMeta> = {
     archetype: "physiological-vital",
   },
   // Body temperature — the population oral-equivalent mean is ~36.6 °C, not
-  // 37.0 °C, with a normal band ~35.7–37.4 °C and fever ≥38.0 °C (J Gen
+  // 37.0 °C, with a normal band ~35.7–37.4 °C and fever ≥ FEVER_BAND_C (J Gen
   // Intern Med systematic review, 2019). C6: the high anchor tightens
   // 37.5 → 37.2 so the band sits below the fever line; sites differ by up
-  // to ~1 °C, so the read is a coarse placement only.
+  // to ~1 °C, so the read is a coarse placement only. D3-H1: the fever line is
+  // the canonical `FEVER_BAND_C`, paired in one place with the engine's
+  // sustained-fever escalation `FEVER_RED_FLAG_C`.
   BODY_TEMPERATURE: {
     id: "BODY_TEMPERATURE",
     measurementType: "BODY_TEMPERATURE",
@@ -205,6 +215,7 @@ const REGISTRY: Record<MetricStatusMetricId, MetricStatusMeta> = {
     unit: "°C",
     direction: "target-band",
     normalRange: { low: 36.1, high: 37.2 },
+    feverBandC: FEVER_BAND_C,
     archetype: "physiological-vital",
   },
   SKIN_TEMPERATURE: {