diff --git a/src/lib/fhir/__tests__/build-bundle.test.ts b/src/lib/fhir/__tests__/build-bundle.test.ts
index a7d350c4e..b454d2002 100644
--- a/src/lib/fhir/__tests__/build-bundle.test.ts
+++ b/src/lib/fhir/__tests__/build-bundle.test.ts
@@ -493,11 +493,11 @@ describe("buildFhirDocumentBundle", () => {
     const coding = stmt?.medicationCodeableConcept.coding;
     expect(stmt?.medicationCodeableConcept.text).toBe("Mounjaro");
     expect(coding).toHaveLength(2);
-    // ATC is primary (first), with the name as display.
+    // ATC is primary (first). No display: the user's name is not the ATC
+    // name for the code, and the validator rejects it; the name is `.text`.
     expect(coding?.[0]).toEqual({
       system: "http://www.whocc.no/atc",
       code: "A10BX10",
-      display: "Mounjaro",
     });
     // RxNorm is secondary, no display.
     expect(coding?.[1]).toEqual({
@@ -578,7 +578,7 @@ describe("buildFhirDocumentBundle", () => {
     expect(a.dosage?.site?.coding?.[0]).toEqual({
       system: "http://snomed.info/sct",
       code: "818983003",
-      display: "Abdomen structure",
+      display: "Abdomen",
     });
   });
 
@@ -712,14 +712,14 @@ describe("buildFhirDocumentBundle", () => {
 
   it("maps every InjectionSite enum value to its body-region SNOMED concept, preserving laterality in `.text`", () => {
     const cases: Array<[string, string, string]> = [
-      ["ABDOMEN_LEFT", "818983003", "Abdomen structure"],
-      ["ABDOMEN_RIGHT", "818983003", "Abdomen structure"],
-      ["ABDOMEN_UPPER_LEFT", "818983003", "Abdomen structure"],
-      ["ABDOMEN_UPPER_RIGHT", "818983003", "Abdomen structure"],
+      ["ABDOMEN_LEFT", "818983003", "Abdomen"],
+      ["ABDOMEN_RIGHT", "818983003", "Abdomen"],
+      ["ABDOMEN_UPPER_LEFT", "818983003", "Abdomen"],
+      ["ABDOMEN_UPPER_RIGHT", "818983003", "Abdomen"],
       ["THIGH_LEFT", "68367000", "Thigh structure"],
       ["THIGH_RIGHT", "68367000", "Thigh structure"],
-      ["UPPER_ARM_LEFT", "40983000", "Structure of upper arm"],
-      ["UPPER_ARM_RIGHT", "40983000", "Structure of upper arm"],
+      ["UPPER_ARM_LEFT", "40983000", "Upper arm structure"],
+      ["UPPER_ARM_RIGHT", "40983000", "Upper arm structure"],
     ];
     for (const [site, code, display] of cases) {
       const bundle = buildFhirDocumentBundle(
@@ -846,13 +846,12 @@ describe("buildFhirDocumentBundle", () => {
     expect(stmtCoding?.[0]).toEqual({
       system: "http://www.whocc.no/atc",
       code: "A10BK03",
-      display: "Empagliflozin",
     });
     expect(stmtCoding?.[1]).toEqual({
       system: "http://fhir.de/CodeSystem/bfarm/atc",
       code: "A10BK03",
-      display: "Empagliflozin",
     });
+    expect(stmt?.medicationCodeableConcept.text).toBe("Empagliflozin");
 
     // The administration concept reflects the flag identically; RxNorm follows.
     const adminCoding =
@@ -909,8 +908,12 @@ describe("buildFhirDocumentBundle", () => {
     const moodObs = bundle.entry
       .map((e) => e.resource)
       .filter((r): r is FhirObservation => r.resourceType === "Observation")
-      .find((o) => o.code.coding?.some((c) => c.code === "76542-6"));
+      .find((o) => o.code.text === "Mood (average over period)");
     expect(moodObs?.valueQuantity?.value).toBe(3.6);
+    // 76542-6 does not exist in LOINC: text-only, and a survey finding, not
+    // a vital sign (so the vital-signs panel does not claim it).
+    expect(moodObs?.code.coding).toBeUndefined();
+    expect(moodObs?.category?.[0]?.coding?.[0]?.code).toBe("survey");
   });
 
   it("emits no Observation for a type with no readings (empty domain)", () => {
@@ -953,7 +956,7 @@ describe("buildFhirDocumentBundle", () => {
     expect(spo2?.valueQuantity?.code).toBe("%");
   });
 
-  it("maps VO2max to 96402-2 with the iOS display", () => {
+  it("maps VO2max to the HealthKit identifier, not the nonexistent LOINC 96402-2", () => {
     const bundle = buildFhirDocumentBundle(
       makeData({
         measurements: {
@@ -963,10 +966,15 @@ describe("buildFhirDocumentBundle", () => {
       { insuranceNumber: null },
       FIXED_NOW,
     );
-    const coding = observationsOf(bundle)
-      .flatMap((o) => o.code.coding ?? [])
-      .find((c) => c.code === "96402-2");
-    expect(coding?.display).toBe("Oxygen consumption maximum during exercise");
+    const codings = observationsOf(bundle).flatMap((o) => o.code.coding ?? []);
+    expect(codings.some((c) => c.code === "96402-2")).toBe(false);
+    const coding = codings.find(
+      (c) => c.code === "HKQuantityTypeIdentifierVO2Max",
+    );
+    expect(coding?.system).toBe(
+      "https://healthlog.dev/fhir/CodeSystem/healthkit",
+    );
+    expect(coding?.display).toBe("VO2 max (estimated)");
   });
 
   it("emits steps with UCUM {steps}", () => {
@@ -1008,7 +1016,7 @@ describe("buildFhirDocumentBundle", () => {
     expect(sleep?.valueQuantity?.value).toBe(7.5);
   });
 
-  it("maps body water + bone mass to the iOS-locked LOINC codes", () => {
+  it("maps body water + bone mass to the LOINC body-composition terms", () => {
     const bundle = buildFhirDocumentBundle(
       makeData({
         measurements: {
@@ -1022,10 +1030,14 @@ describe("buildFhirDocumentBundle", () => {
       FIXED_NOW,
     );
     const water = observationsOf(bundle).find((o) =>
-      o.code.coding?.some((c) => c.code === "73704-9"),
+      o.code.coding?.some(
+        (c) => c.code === "101683-1" && c.display === "Body water mass",
+      ),
     );
     const bone = observationsOf(bundle).find((o) =>
-      o.code.coding?.some((c) => c.code === "73708-0"),
+      o.code.coding?.some(
+        (c) => c.code === "101685-6" && c.display === "Body bone mass",
+      ),
     );
     expect(water?.valueQuantity?.code).toBe("kg");
     expect(bone?.valueQuantity?.code).toBe("kg");
@@ -1049,8 +1061,11 @@ describe("buildFhirDocumentBundle", () => {
     const energy = observationsOf(bundle).find((o) =>
       o.code.coding?.some((c) => c.code === "41981-2"),
     );
+    // Not 41957-2 (a 24-hour mean): a HealthKit walking-speed reading.
     const speed = observationsOf(bundle).find((o) =>
-      o.code.coding?.some((c) => c.code === "41957-2"),
+      o.code.coding?.some(
+        (c) => c.code === "HKQuantityTypeIdentifierWalkingSpeed",
+      ),
     );
     expect(energy?.valueQuantity?.code).toBe("kcal");
     // Walking speed FHIR value stays m/s (no km/h conversion).
diff --git a/src/lib/fhir/__tests__/cycle-observations.test.ts b/src/lib/fhir/__tests__/cycle-observations.test.ts
index bff847b86..330a83d63 100644
--- a/src/lib/fhir/__tests__/cycle-observations.test.ts
+++ b/src/lib/fhir/__tests__/cycle-observations.test.ts
@@ -4,11 +4,7 @@ import type { DoctorReportData } from "@/lib/doctor-report-data";
 import { computeGlucoseClinicalMetrics } from "@/lib/analytics/glucose-metrics";
 import { cycleObservationsFromReportData } from "@/lib/fhir/resources";
 import { buildFhirDocumentBundle } from "@/lib/fhir/build-bundle";
-import {
-  LMP_LOINC,
-  CYCLE_LENGTH_LOINC,
-  PERIOD_LENGTH_LOINC,
-} from "@/lib/fhir/loinc-map";
+import { LMP_LOINC } from "@/lib/fhir/loinc-map";
 
 function baseData(overrides?: Partial<DoctorReportData>): DoctorReportData {
   return {
@@ -68,9 +64,17 @@ describe("fhir/cycle observations", () => {
     const codes = obs.flatMap((o) =>
       (o.code.coding ?? []).map((c) => c.code).filter(Boolean),
     );
-    expect(codes).toContain(LMP_LOINC);
-    expect(codes).toContain(CYCLE_LENGTH_LOINC);
-    expect(codes).toContain(PERIOD_LENGTH_LOINC);
+    // LMP is the only coded one. The averages are text-only: 64700-8 and
+    // 64698-4, used before, are PhenX questionnaire items, not these values.
+    expect(codes).toEqual([LMP_LOINC]);
+    const cycleLength = obs.find(
+      (o) => o.code.text === "Average menstrual cycle length",
+    );
+    const periodLength = obs.find(
+      (o) => o.code.text === "Average period length",
+    );
+    expect(cycleLength?.code.coding).toBeUndefined();
+    expect(periodLength?.code.coding).toBeUndefined();
 
     const lmp = obs.find((o) =>
       (o.code.coding ?? []).some((c) => c.code === LMP_LOINC),
diff --git a/src/lib/fhir/__tests__/glucose-clinical-observations.test.ts b/src/lib/fhir/__tests__/glucose-clinical-observations.test.ts
index 15b065a4c..1274631e9 100644
--- a/src/lib/fhir/__tests__/glucose-clinical-observations.test.ts
+++ b/src/lib/fhir/__tests__/glucose-clinical-observations.test.ts
@@ -6,7 +6,6 @@ import {
   GLUCOSE_TIR_LOINC,
   GLUCOSE_GMI_LOINC,
   GLUCOSE_MEAN_LOINC,
-  GLUCOSE_EA1C_LOINC,
 } from "@/lib/fhir/loinc-map";
 
 import { buildFhirDocumentBundle } from "../build-bundle";
@@ -89,7 +88,28 @@ describe("clinical glucose-panel FHIR Observations", () => {
     expect(codes).toContain(GLUCOSE_TIR_LOINC);
     expect(codes).toContain(GLUCOSE_GMI_LOINC);
     expect(codes).toContain(GLUCOSE_MEAN_LOINC);
-    expect(codes).toContain(GLUCOSE_EA1C_LOINC);
+
+    // Each coded term carries the display LOINC publishes for it.
+    const displayOf = (code: string) =>
+      observationsOf(bundle)
+        .flatMap((o) => o.code.coding ?? [])
+        .find((c) => c.code === code)?.display;
+    expect(displayOf(GLUCOSE_TIR_LOINC)).toBe(
+      "Glucose measurements in range out of Total glucose measurements during reporting period",
+    );
+    expect(displayOf(GLUCOSE_GMI_LOINC)).toBe("Glucose management indicator");
+    expect(displayOf(GLUCOSE_MEAN_LOINC)).toBe(
+      "Average glucose [Mass/volume] in Interstitial fluid during Reporting Period",
+    );
+
+    // Estimated A1C is text-only: 41995-2, used before, is a measured
+    // "Hemoglobin A1c [Mass/volume] in Blood".
+    const ea1c = observationsOf(bundle).find(
+      (o) => o.code.text === "Estimated A1C",
+    );
+    expect(ea1c).toBeDefined();
+    expect(ea1c?.code.coding).toBeUndefined();
+    expect(codes).not.toContain("41995-2");
   });
 
   it("emits a percent-valued, UCUM-coded TIR Observation", () => {
@@ -122,6 +142,8 @@ describe("clinical glucose-panel FHIR Observations", () => {
     expect(codes).not.toContain(GLUCOSE_TIR_LOINC);
     expect(codes).not.toContain(GLUCOSE_GMI_LOINC);
     expect(codes).not.toContain(GLUCOSE_MEAN_LOINC);
-    expect(codes).not.toContain(GLUCOSE_EA1C_LOINC);
+    expect(
+      observationsOf(bundle).some((o) => o.code.text === "Estimated A1C"),
+    ).toBe(false);
   });
 });
diff --git a/src/lib/fhir/__tests__/lab-loinc-locales.test.ts b/src/lib/fhir/__tests__/lab-loinc-locales.test.ts
index 2e4363e45..bbe104493 100644
--- a/src/lib/fhir/__tests__/lab-loinc-locales.test.ts
+++ b/src/lib/fhir/__tests__/lab-loinc-locales.test.ts
@@ -35,7 +35,7 @@ describe("resolveLabCoding — the analyte name in every shipped locale", () =>
     ["Ferrytyna", "2276-4"],
     ["Hémoglobine", "718-7"],
     ["Emoglobina", "718-7"],
-    ["Cholestérol LDL", "18262-6"],
+    ["Cholestérol LDL", "2089-1"],
     ["Colesterol HDL", "2085-9"],
     ["Triglycérides", "2571-8"],
     ["Trójglicerydy", "2571-8"],
@@ -80,8 +80,8 @@ describe("resolveLabCoding — the analyte name in every shipped locale", () =>
 describe("resolveLabCoding — the existing English and German behaviour", () => {
   it.each([
     ["HbA1c", "4548-4"],
-    ["LDL-C", "18262-6"],
-    ["LDL Cholesterol", "18262-6"],
+    ["LDL-C", "2089-1"],
+    ["LDL Cholesterol", "2089-1"],
     ["Gesamtcholesterin", "2093-3"],
     ["Kreatinin", "2160-0"],
     ["GPT", "1742-6"],
diff --git a/src/lib/fhir/__tests__/lab-observations.test.ts b/src/lib/fhir/__tests__/lab-observations.test.ts
index 0feb2cc46..8ad312ffc 100644
--- a/src/lib/fhir/__tests__/lab-observations.test.ts
+++ b/src/lib/fhir/__tests__/lab-observations.test.ts
@@ -224,17 +224,17 @@ describe("lab-result LOINC + canonical UCUM coding (v1.18.8)", () => {
 
   it("stamps the canonical UCUM code when the unit matches", () => {
     const o = labOf("LDL", "mg/dL", 110);
-    expect(o?.code.coding?.[0].code).toBe("18262-6");
+    expect(o?.code.coding?.[0].code).toBe("2089-1");
     expect(o?.valueQuantity?.system).toBe("http://unitsofmeasure.org");
     expect(o?.valueQuantity?.code).toBe("mg/dL");
     expect(o?.valueQuantity?.unit).toBe("mg/dL");
   });
 
   it("resolves analyte aliases to the same canonical LOINC", () => {
-    // "LDL", "LDL-C", "LDL Cholesterol" all fold to 18262-6.
+    // "LDL", "LDL-C", "LDL Cholesterol" all fold to 2089-1.
     for (const name of ["LDL-C", "LDL Cholesterol", "ldl_c"]) {
       const o = labOf(name, "mg/dL", 110);
-      expect(o?.code.coding?.[0].code).toBe("18262-6");
+      expect(o?.code.coding?.[0].code).toBe("2089-1");
     }
     // German alias for total cholesterol.
     const chol = labOf("Gesamtcholesterin", "mg/dL", 180);
diff --git a/src/lib/fhir/__tests__/terminology-displays.test.ts b/src/lib/fhir/__tests__/terminology-displays.test.ts
new file mode 100644
index 000000000..f712fb2e0
--- /dev/null
+++ b/src/lib/fhir/__tests__/terminology-displays.test.ts
@@ -0,0 +1,175 @@
+/**
+ * Codes and displays the official HL7 FHIR validator (R4, tx.fhir.org)
+ * rejected before v1.39.3, pinned at the values it accepts. A display must be
+ * one LOINC or SNOMED CT publishes for the code; a code must be active and
+ * mean what the Observation says.
+ */
+import { describe, expect, it } from "vitest";
+
+import { computeGlucoseClinicalMetrics } from "@/lib/analytics/glucose-metrics";
+import type { DoctorReportData } from "@/lib/doctor-report-data";
+import { buildFhirDocumentBundle } from "@/lib/fhir/build-bundle";
+import { resolveLabCoding } from "@/lib/fhir/lab-loinc";
+import type { FhirCoding, FhirObservation } from "@/lib/fhir/types";
+
+const FIXED_NOW = new Date("2026-05-03T12:00:00.000Z");
+
+function codings(overrides: Partial<DoctorReportData>): FhirCoding[] {
+  const data = {
+    period: {
+      days: 90,
+      since: "2026-02-02T00:00:00.000Z",
+      start: "2026-02-02T00:00:00.000Z",
+      end: "2026-05-03T12:00:00.000Z",
+    },
+    patient: { username: "sample-user", dateOfBirth: null, gender: null },
+    practiceName: null,
+    measurements: {},
+    stats: {},
+    glucoseStats: {},
+    glucoseRanges: {},
+    glucoseClinical: computeGlucoseClinicalMetrics([], { now: FIXED_NOW }),
+    glucoseUnit: "mg/dL",
+    bmi: null,
+    compliance: {},
+    medications: [],
+    mood: null,
+    glp1: null,
+    ...overrides,
+  } as DoctorReportData;
+  const bundle = buildFhirDocumentBundle(
+    data,
+    { insuranceNumber: null },
+    FIXED_NOW,
+  );
+  return bundle.entry
+    .map((e) => e.resource)
+    .filter((r): r is FhirObservation => r.resourceType === "Observation")
+    .flatMap((o) => [
+      ...(o.code.coding ?? []),
+      ...(o.component ?? []).flatMap((c) => c.code.coding ?? []),
+    ]);
+}
+
+describe("LOINC displays accepted by the validator", () => {
+  it("names the blood-pressure panel and its components as LOINC does", () => {
+    const all = codings({
+      measurements: {
+        BLOOD_PRESSURE_SYS: [
+          { value: 120, measuredAt: "2026-04-30T08:00:00.000Z" },
+        ],
+        BLOOD_PRESSURE_DIA: [
+          { value: 78, measuredAt: "2026-04-30T08:00:00.000Z" },
+        ],
+      },
+    });
+    const display = (code: string) => all.find((c) => c.code === code)?.display;
+    expect(display("85354-9")).toBe(
+      "Blood pressure panel with all children optional",
+    );
+    expect(display("8480-6")).toBe("Systolic blood pressure");
+    expect(display("8462-4")).toBe("Diastolic blood pressure");
+  });
+
+  it("names medication adherence as LOINC does", () => {
+    const all = codings({
+      compliance: {
+        "Example Drug": { total: 10, taken: 9, skipped: 1, missed: 0 },
+      },
+    });
+    expect(all.find((c) => c.code === "71799-1")?.display).toBe(
+      "Adherence to prescribed medication instructions [Reported]",
+    );
+  });
+});
+
+describe("R4 vital-signs profile codes", () => {
+  it("adds the heart-rate and oxygen-saturation magic codes beside the specific ones", () => {
+    const all = codings({
+      measurements: {
+        RESTING_HEART_RATE: [
+          { value: 54, measuredAt: "2026-04-30T08:00:00.000Z" },
+        ],
+        OXYGEN_SATURATION: [
+          { value: 97, measuredAt: "2026-04-30T08:00:00.000Z" },
+        ],
+      },
+    });
+    const codes = all.map((c) => c.code);
+    expect(codes).toEqual(
+      expect.arrayContaining(["40443-4", "8867-4", "59408-5", "2708-6"]),
+    );
+  });
+});
+
+describe("medication codings", () => {
+  it("carries no display on an ATC coding; the user's name stays on text", () => {
+    const bundle = buildFhirDocumentBundle(
+      {
+        period: {
+          days: 90,
+          since: "2026-02-02T00:00:00.000Z",
+          start: "2026-02-02T00:00:00.000Z",
+          end: "2026-05-03T12:00:00.000Z",
+        },
+        patient: { username: "sample-user", dateOfBirth: null, gender: null },
+        practiceName: null,
+        measurements: {},
+        stats: {},
+        glucoseStats: {},
+        glucoseRanges: {},
+        glucoseClinical: computeGlucoseClinicalMetrics([], { now: FIXED_NOW }),
+        glucoseUnit: "mg/dL",
+        bmi: null,
+        compliance: {},
+        medications: [
+          { name: "Delix 5", dose: "5mg", schedules: [], atcCode: "C09AA05" },
+        ],
+        mood: null,
+        glp1: null,
+      } as unknown as DoctorReportData,
+      { insuranceNumber: null },
+      FIXED_NOW,
+      { germanAtc: true },
+    );
+    const stmt = bundle.entry
+      .map((e) => e.resource)
+      .find((r) => r.resourceType === "MedicationStatement");
+    if (stmt?.resourceType !== "MedicationStatement") throw new Error("none");
+    expect(stmt.medicationCodeableConcept.text).toBe("Delix 5");
+    expect(stmt.medicationCodeableConcept.coding).toEqual([
+      { system: "http://www.whocc.no/atc", code: "C09AA05" },
+      { system: "http://fhir.de/CodeSystem/bfarm/atc", code: "C09AA05" },
+    ]);
+  });
+});
+
+describe("lab LOINC terms", () => {
+  it.each([
+    // Method-less LDL; 18262-6 is the direct-assay term.
+    [
+      "LDL-C",
+      "mg/dL",
+      "2089-1",
+      "Cholesterol in LDL [Mass/volume] in Serum or Plasma",
+    ],
+    // Total 25-OH vitamin D; 1989-3 is D3 alone.
+    [
+      "Vitamin D",
+      "ng/mL",
+      "62292-8",
+      "25-Hydroxyvitamin D3+25-Hydroxyvitamin D2 [Mass/volume] in Serum or Plasma",
+    ],
+    // Formula-less eGFR; 33914-3 (MDRD) is DISCOURAGED.
+    [
+      "eGFR",
+      "mL/min/1.73m2",
+      "69405-9",
+      "Glomerular filtration rate [Volume Rate/Area] in Serum, Plasma or Blood by based on 1.73 sq M",
+    ],
+  ])("codes %s as %s", (analyte, unit, code, display) => {
+    const coding = resolveLabCoding(analyte, unit);
+    expect(coding?.loinc).toBe(code);
+    expect(coding?.display).toBe(display);
+  });
+});
diff --git a/src/lib/fhir/lab-loinc.ts b/src/lib/fhir/lab-loinc.ts
index 1d6562b56..8b2a51158 100644
--- a/src/lib/fhir/lab-loinc.ts
+++ b/src/lib/fhir/lab-loinc.ts
@@ -79,8 +79,10 @@ const LAB_LOINC_BY_KEY: Record<string, LabLoincMapping> = {
     display: "Hemoglobin A1c/Hemoglobin.total in Blood",
     ucum: "%",
   },
+  // Method-less LDL: a recorded value does not say whether it was measured
+  // directly (18262-6) or calculated (13457-7).
   ldlc: {
-    loinc: "18262-6",
+    loinc: "2089-1",
     display: "Cholesterol in LDL [Mass/volume] in Serum or Plasma",
     ucum: "mg/dL",
   },
@@ -109,10 +111,11 @@ const LAB_LOINC_BY_KEY: Record<string, LabLoincMapping> = {
     display: "Thyrotropin [Units/volume] in Serum or Plasma",
     ucum: "m[IU]/L",
   },
+  // Total 25-OH vitamin D (D2+D3), the value labs report; 1989-3 is D3 alone.
   vitamind: {
-    loinc: "1989-3",
+    loinc: "62292-8",
     display:
-      "25-hydroxyvitamin D2+25-hydroxyvitamin D3 [Mass/volume] in Serum or Plasma",
+      "25-Hydroxyvitamin D3+25-Hydroxyvitamin D2 [Mass/volume] in Serum or Plasma",
     ucum: "ng/mL",
   },
   creatinine: {
@@ -120,10 +123,12 @@ const LAB_LOINC_BY_KEY: Record<string, LabLoincMapping> = {
     display: "Creatinine [Mass/volume] in Serum or Plasma",
     ucum: "mg/dL",
   },
+  // Formula-less eGFR per 1.73 m2. A recorded value does not name its
+  // formula, and 33914-3 (MDRD) is DISCOURAGED in LOINC.
   egfr: {
-    loinc: "33914-3",
+    loinc: "69405-9",
     display:
-      "Glomerular filtration rate/1.73 sq M.predicted by Creatinine-based formula (MDRD)",
+      "Glomerular filtration rate [Volume Rate/Area] in Serum, Plasma or Blood by based on 1.73 sq M",
     ucum: "mL/min/{1.73_m2}",
   },
   alt: {
diff --git a/src/lib/fhir/loinc-map.ts b/src/lib/fhir/loinc-map.ts
index 4920d04fa..aab8101d3 100644
--- a/src/lib/fhir/loinc-map.ts
+++ b/src/lib/fhir/loinc-map.ts
@@ -95,18 +95,21 @@ export const GLUCOSE_TIR_LOINC = "97510-2";
 export const GLUCOSE_GMI_LOINC = "97506-0";
 /** Mean glucose over the reporting period. */
 export const GLUCOSE_MEAN_LOINC = "97507-8";
-/** Estimated A1C (ADAG, derived from mean glucose). */
-export const GLUCOSE_EA1C_LOINC = "41995-2";
+/*
+ * Estimated A1C (ADAG, derived from mean glucose) has no LOINC term of its
+ * own: 41995-2, used here before, is a measured "Hemoglobin A1c
+ * [Mass/volume] in Blood". The builder emits it text-only.
+ */
 
 /** Medication-adherence Observation LOINC. */
 export const MEDICATION_ADHERENCE_LOINC = "71799-1";
-/** Mood Observation LOINC (opt-in only). */
-export const MOOD_LOINC = "76542-6";
 
 /* ── Cycle / reproductive-health LOINCs (v1.15.0, opt-in only) ──────── */
 /** Last menstrual period (LMP) start date. */
 export const LMP_LOINC = "8665-2";
-/** Menstrual cycle length [time]. */
-export const CYCLE_LENGTH_LOINC = "64700-8";
-/** Length of menses (period / bleeding duration). */
-export const PERIOD_LENGTH_LOINC = "64698-4";
+/*
+ * Average cycle length and average period length have no LOINC term for a
+ * value computed over many cycles. 64700-8 and 64698-4, used before, are
+ * PhenX questionnaire items (a remembered typical cycle; a breastfeeding
+ * question), so both Observations are text-only.
+ */
diff --git a/src/lib/fhir/resources/common.ts b/src/lib/fhir/resources/common.ts
index 97fa59619..920ef0592 100644
--- a/src/lib/fhir/resources/common.ts
+++ b/src/lib/fhir/resources/common.ts
@@ -84,6 +84,24 @@ export function categoryConcept(category: string): FhirCodeableConcept {
   };
 }
 
+/**
+ * R4 vital-signs profiles require a "magic" LOINC code on `Observation.code`
+ * and allow a more specific code beside it
+ * (https://hl7.org/fhir/R4/observation-vitalsigns.html). A resting heart rate
+ * is a heart rate (8867-4) and a pulse-oximetry SpO2 is an oxygen saturation
+ * (2708-6); without the magic code the validator rejects both Observations.
+ */
+const VITAL_SIGNS_MAGIC_CODE: Record<
+  string,
+  { code: string; display: string }
+> = {
+  "40443-4": { code: "8867-4", display: "Heart rate" },
+  "59408-5": {
+    code: "2708-6",
+    display: "Oxygen saturation in Arterial blood",
+  },
+};
+
 export function codeableFromMapping(m: LoincMapping): FhirCodeableConcept {
   if (m.loinc) {
     // HealthKit placeholder codes have no published LOINC term; they must not
@@ -93,8 +111,15 @@ export function codeableFromMapping(m: LoincMapping): FhirCodeableConcept {
     const system = m.loinc.startsWith("HKQuantityTypeIdentifier")
       ? HEALTHKIT_CODESYSTEM
       : LOINC_SYSTEM;
+    const magic =
+      system === LOINC_SYSTEM ? VITAL_SIGNS_MAGIC_CODE[m.loinc] : undefined;
     return {
-      coding: [{ system, code: m.loinc, display: m.display }],
+      coding: [
+        { system, code: m.loinc, display: m.display },
+        ...(magic
+          ? [{ system: LOINC_SYSTEM, code: magic.code, display: magic.display }]
+          : []),
+      ],
       text: m.display,
     };
   }
diff --git a/src/lib/fhir/resources/cycle.ts b/src/lib/fhir/resources/cycle.ts
index a954db26d..71d48e289 100644
--- a/src/lib/fhir/resources/cycle.ts
+++ b/src/lib/fhir/resources/cycle.ts
@@ -1,18 +1,13 @@
 /**
  * v1.15.0 — the cycle / reproductive-health Observations from the opt-in cycle
- * summary: LMP (LOINC 8665-2, a date value), average cycle length (64700-8,
- * days), average period length (64698-4, days), and the current phase
+ * summary: LMP (LOINC 8665-2, a date value), average cycle length and average
+ * period length (text-only, days; see `loinc-map.ts`), and the current phase
  * (text-only survey finding). Absent when the aggregator carried no cycle
  * summary (toggle off or no observed cycle). Ids run `obs-cycle-N` so they
  * never collide with the main `obs-N` sequence.
  */
 import type { DoctorReportData } from "@/lib/doctor-report-data";
-import {
-  LOINC_SYSTEM,
-  LMP_LOINC,
-  CYCLE_LENGTH_LOINC,
-  PERIOD_LENGTH_LOINC,
-} from "@/lib/fhir/loinc-map";
+import { LOINC_SYSTEM, LMP_LOINC } from "@/lib/fhir/loinc-map";
 import { ucumQuantity } from "@/lib/fhir/ucum";
 import type { FhirObservation } from "@/lib/fhir/types";
 import {
@@ -76,16 +71,9 @@ export function cycleObservationsFromReportData(
       id: next(),
       status: "final",
       category: [categoryConcept("survey")],
-      code: {
-        coding: [
-          {
-            system: LOINC_SYSTEM,
-            code: CYCLE_LENGTH_LOINC,
-            display: "Menstrual cycle length",
-          },
-        ],
-        text: "Average menstrual cycle length",
-      },
+      // Text-only: no LOINC term for a cycle length averaged over the
+      // observed cycles (see `loinc-map.ts`).
+      code: { text: "Average menstrual cycle length" },
       subject: patientRef,
       effectivePeriod,
       valueQuantity: ucumQuantity(cycle.averageCycleLengthDays, "d"),
@@ -107,16 +95,8 @@ export function cycleObservationsFromReportData(
       id: next(),
       status: "final",
       category: [categoryConcept("survey")],
-      code: {
-        coding: [
-          {
-            system: LOINC_SYSTEM,
-            code: PERIOD_LENGTH_LOINC,
-            display: "Length of menses",
-          },
-        ],
-        text: "Average period length",
-      },
+      // Text-only, like the cycle length above.
+      code: { text: "Average period length" },
       subject: patientRef,
       effectivePeriod,
       valueQuantity: ucumQuantity(cycle.averagePeriodLengthDays, "d"),
diff --git a/src/lib/fhir/resources/glucose.ts b/src/lib/fhir/resources/glucose.ts
index 6bb30e618..0ec140729 100644
--- a/src/lib/fhir/resources/glucose.ts
+++ b/src/lib/fhir/resources/glucose.ts
@@ -15,7 +15,6 @@ import {
   GLUCOSE_TIR_LOINC,
   GLUCOSE_GMI_LOINC,
   GLUCOSE_MEAN_LOINC,
-  GLUCOSE_EA1C_LOINC,
 } from "@/lib/fhir/loinc-map";
 import { ucumQuantity } from "@/lib/fhir/ucum";
 import type { FhirObservation } from "@/lib/fhir/types";
@@ -92,7 +91,8 @@ export function glucoseClinicalObservations(
   const observations: FhirObservation[] = [];
 
   const push = (opts: {
-    loinc?: string;
+    /** LOINC code and its LOINC display; absent for a text-only concept. */
+    loinc?: { code: string; display: string };
     text: string;
     value: number;
     unit: string;
@@ -106,7 +106,11 @@ export function glucoseClinicalObservations(
       code: opts.loinc
         ? {
             coding: [
-              { system: LOINC_SYSTEM, code: opts.loinc, display: opts.text },
+              {
+                system: LOINC_SYSTEM,
+                code: opts.loinc.code,
+                display: opts.loinc.display,
+              },
             ],
             text: opts.text,
           }
@@ -128,7 +132,11 @@ export function glucoseClinicalObservations(
 
   if (clinical.distribution) {
     push({
-      loinc: GLUCOSE_TIR_LOINC,
+      loinc: {
+        code: GLUCOSE_TIR_LOINC,
+        display:
+          "Glucose measurements in range out of Total glucose measurements during reporting period",
+      },
       text: timeInRangeDisplay(glucoseUnit),
       value: Math.round(clinical.distribution.tir * 1000) / 10,
       unit: "%",
@@ -136,7 +144,11 @@ export function glucoseClinicalObservations(
   }
   if (clinical.meanMgdl !== null) {
     push({
-      loinc: GLUCOSE_MEAN_LOINC,
+      loinc: {
+        code: GLUCOSE_MEAN_LOINC,
+        display:
+          "Average glucose [Mass/volume] in Interstitial fluid during Reporting Period",
+      },
       text: "Mean glucose",
       value: convertGlucose(clinical.meanMgdl, glucoseUnit),
       unit: glucoseUnit,
@@ -144,7 +156,10 @@ export function glucoseClinicalObservations(
   }
   if (clinical.gmi !== null) {
     push({
-      loinc: GLUCOSE_GMI_LOINC,
+      loinc: {
+        code: GLUCOSE_GMI_LOINC,
+        display: "Glucose management indicator",
+      },
       text: "Glucose Management Indicator (GMI)",
       value: Math.round(clinical.gmi * 10) / 10,
       unit: "%",
@@ -152,7 +167,8 @@ export function glucoseClinicalObservations(
   }
   if (clinical.estimatedA1c !== null) {
     push({
-      loinc: GLUCOSE_EA1C_LOINC,
+      // Text-only: no LOINC term exists for an A1C estimated from mean
+      // glucose (see `loinc-map.ts`).
       text: "Estimated A1C",
       value: Math.round(clinical.estimatedA1c * 10) / 10,
       unit: "%",
diff --git a/src/lib/fhir/resources/medications.ts b/src/lib/fhir/resources/medications.ts
index 233caee61..ea14d2be7 100644
--- a/src/lib/fhir/resources/medications.ts
+++ b/src/lib/fhir/resources/medications.ts
@@ -35,10 +35,13 @@ function medicationConcept(
   germanAtc: boolean,
 ): FhirCodeableConcept {
   const coding: NonNullable<FhirCodeableConcept["coding"]> = [];
+  // No `display` on the ATC codings: a coding's display must be the code
+  // system's own name for the code ("ramipril"), and the user's name for the
+  // medication ("Delix 5") is not that. It rides `.text`.
   if (atcCode) {
-    coding.push({ system: ATC_SYSTEM, code: atcCode, display: name });
+    coding.push({ system: ATC_SYSTEM, code: atcCode });
     if (germanAtc) {
-      coding.push({ system: ATC_BFARM_SYSTEM, code: atcCode, display: name });
+      coding.push({ system: ATC_BFARM_SYSTEM, code: atcCode });
     }
   }
   if (rxNormCode) {
@@ -117,14 +120,14 @@ function routeConcept(
  * no information is lost.
  */
 const SITE_SNOMED: Record<string, { code: string; display: string }> = {
-  ABDOMEN_LEFT: { code: "818983003", display: "Abdomen structure" },
-  ABDOMEN_RIGHT: { code: "818983003", display: "Abdomen structure" },
-  ABDOMEN_UPPER_LEFT: { code: "818983003", display: "Abdomen structure" },
-  ABDOMEN_UPPER_RIGHT: { code: "818983003", display: "Abdomen structure" },
+  ABDOMEN_LEFT: { code: "818983003", display: "Abdomen" },
+  ABDOMEN_RIGHT: { code: "818983003", display: "Abdomen" },
+  ABDOMEN_UPPER_LEFT: { code: "818983003", display: "Abdomen" },
+  ABDOMEN_UPPER_RIGHT: { code: "818983003", display: "Abdomen" },
   THIGH_LEFT: { code: "68367000", display: "Thigh structure" },
   THIGH_RIGHT: { code: "68367000", display: "Thigh structure" },
-  UPPER_ARM_LEFT: { code: "40983000", display: "Structure of upper arm" },
-  UPPER_ARM_RIGHT: { code: "40983000", display: "Structure of upper arm" },
+  UPPER_ARM_LEFT: { code: "40983000", display: "Upper arm structure" },
+  UPPER_ARM_RIGHT: { code: "40983000", display: "Upper arm structure" },
 };
 
 function siteConcept(injectionSite: string): FhirCodeableConcept {
diff --git a/src/lib/fhir/resources/observation.ts b/src/lib/fhir/resources/observation.ts
index 45a8bc4a8..72fc8d3af 100644
--- a/src/lib/fhir/resources/observation.ts
+++ b/src/lib/fhir/resources/observation.ts
@@ -22,7 +22,6 @@ import {
   BP_DIA_LOINC,
   BP_UNIT,
   MEDICATION_ADHERENCE_LOINC,
-  MOOD_LOINC,
 } from "@/lib/fhir/loinc-map";
 import { ucumQuantity } from "@/lib/fhir/ucum";
 import type { FhirObservation } from "@/lib/fhir/types";
@@ -104,7 +103,7 @@ function bloodPressureObservation(
           {
             system: LOINC_SYSTEM,
             code: BP_PANEL_LOINC,
-            display: "Blood pressure panel",
+            display: "Blood pressure panel with all children optional",
           },
         ],
         text: "Blood pressure",
@@ -116,7 +115,11 @@ function bloodPressureObservation(
         {
           code: {
             coding: [
-              { system: LOINC_SYSTEM, code: BP_SYS_LOINC, display: "Systolic" },
+              {
+                system: LOINC_SYSTEM,
+                code: BP_SYS_LOINC,
+                display: "Systolic blood pressure",
+              },
             ],
           },
           valueQuantity: ucumQuantity(sys.value, BP_UNIT),
@@ -127,7 +130,7 @@ function bloodPressureObservation(
               {
                 system: LOINC_SYSTEM,
                 code: BP_DIA_LOINC,
-                display: "Diastolic",
+                display: "Diastolic blood pressure",
               },
             ],
           },
@@ -194,7 +197,8 @@ function adherenceObservations(
           {
             system: LOINC_SYSTEM,
             code: MEDICATION_ADHERENCE_LOINC,
-            display: "Medication adherence",
+            display:
+              "Adherence to prescribed medication instructions [Reported]",
           },
         ],
         text: `Medication adherence — ${name}`,
@@ -207,7 +211,13 @@ function adherenceObservations(
   return observations;
 }
 
-/** The opt-in mood average; absent when the toggle is off. */
+/**
+ * The opt-in mood average; absent when the toggle is off.
+ *
+ * Text-only, under `survey`: LOINC has no term for a self-rated mood score
+ * averaged over a period (76542-6, used before, does not exist in LOINC), and
+ * a mood score is not a vital sign, so it must not ride the vital-signs panel.
+ */
 function moodObservation(
   data: DoctorReportData,
   nextId: () => string,
@@ -218,11 +228,8 @@ function moodObservation(
       resourceType: "Observation",
       id: nextId(),
       status: "final",
-      category: [categoryConcept("vital-signs")],
-      code: {
-        coding: [{ system: LOINC_SYSTEM, code: MOOD_LOINC, display: "Mood" }],
-        text: "Mood (average over period)",
-      },
+      category: [categoryConcept("survey")],
+      code: { text: "Mood (average over period)" },
       subject: patientRef,
       effectivePeriod: reportingPeriod(data),
       valueQuantity: ucumQuantity(
diff --git a/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json b/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json
index 716887d9b..ef14ef361 100644
--- a/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json
+++ b/src/lib/signals/__tests__/fixtures/expected-measurement-loinc.json
@@ -48,8 +48,8 @@
     "category": "vital-signs"
   },
   "VO2_MAX": {
-    "loinc": "96402-2",
-    "display": "Oxygen consumption maximum during exercise",
+    "loinc": "HKQuantityTypeIdentifierVO2Max",
+    "display": "VO2 max (estimated)",
     "unit": "mL/min/kg",
     "category": "vital-signs"
   },
@@ -78,32 +78,32 @@
     "category": "activity"
   },
   "WALKING_SPEED": {
-    "loinc": "41957-2",
-    "display": "Gait speed [Velocity] Measured",
+    "loinc": "HKQuantityTypeIdentifierWalkingSpeed",
+    "display": "Walking speed",
     "unit": "m/s",
     "category": "vital-signs"
   },
   "WALKING_ASYMMETRY": {
-    "loinc": "91557-1",
+    "loinc": "HKQuantityTypeIdentifierWalkingAsymmetryPercentage",
     "display": "Walking asymmetry percentage",
     "unit": "%",
     "category": "vital-signs"
   },
   "WALKING_STEP_LENGTH": {
-    "loinc": "41955-6",
-    "display": "Step length Measured",
+    "loinc": "HKQuantityTypeIdentifierWalkingStepLength",
+    "display": "Walking step length",
     "unit": "m",
     "category": "vital-signs"
   },
   "TOTAL_BODY_WATER": {
-    "loinc": "73704-9",
-    "display": "Body water by Bioelectrical impedance analysis",
+    "loinc": "101683-1",
+    "display": "Body water mass",
     "unit": "kg",
     "category": "vital-signs"
   },
   "BONE_MASS": {
-    "loinc": "73708-0",
-    "display": "Bone mineral content by DXA",
+    "loinc": "101685-6",
+    "display": "Body bone mass",
     "unit": "kg",
     "category": "vital-signs"
   },
diff --git a/src/lib/signals/registry.ts b/src/lib/signals/registry.ts
index afb003c53..17ca5d025 100644
--- a/src/lib/signals/registry.ts
+++ b/src/lib/signals/registry.ts
@@ -574,8 +574,11 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "96402-2",
-      display: "Oxygen consumption maximum during exercise",
+      // 96402-2, used before, does not exist in LOINC. The watch estimate is
+      // not a measured exercise-test VO2 peak (94122-9), so the HealthKit
+      // identifier rides the custom system.
+      loinc: "HKQuantityTypeIdentifierVO2Max",
+      display: "VO2 max (estimated)",
       unit: "mL/min/kg",
       category: "vital-signs",
     },
@@ -656,8 +659,9 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "73704-9",
-      display: "Body water by Bioelectrical impedance analysis",
+      // 73704-9, used before, is a nasogastric fluid output.
+      loinc: "101683-1",
+      display: "Body water mass",
       unit: "kg",
       category: "vital-signs",
     },
@@ -677,8 +681,9 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "73708-0",
-      display: "Bone mineral content by DXA",
+      // 73708-0, used before, is "Body fat [Mass] Calculated".
+      loinc: "101685-6",
+      display: "Body bone mass",
       unit: "kg",
       category: "vital-signs",
     },
@@ -821,7 +826,8 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "91557-1",
+      // 91557-1, used before, does not exist in LOINC.
+      loinc: "HKQuantityTypeIdentifierWalkingAsymmetryPercentage",
       display: "Walking asymmetry percentage",
       unit: "%",
       category: "vital-signs",
@@ -864,8 +870,10 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "41955-6",
-      display: "Step length Measured",
+      // 41955-6, used before, is "Distance walked in 1 week"; LOINC has no
+      // step-length term, so the HealthKit identifier rides the custom system.
+      loinc: "HKQuantityTypeIdentifierWalkingStepLength",
+      display: "Walking step length",
       unit: "m",
       category: "vital-signs",
     },
@@ -886,8 +894,10 @@ export const SIGNALS: Record<string, SignalDefinition> = {
       mcp: true,
     },
     fhir: {
-      loinc: "41957-2",
-      display: "Gait speed [Velocity] Measured",
+      // 41957-2, used before, is a 24-hour mean walking speed; the value
+      // here is a HealthKit walking-speed reading.
+      loinc: "HKQuantityTypeIdentifierWalkingSpeed",
+      display: "Walking speed",
       unit: "m/s",
       category: "vital-signs",
     },