diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index c9b3511d3..1b7a1c041 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -74922,6 +74922,11 @@ components:
           type: array
           items:
             $ref: "#/components/schemas/MentalHealthAssessment"
+        trends:
+          description: v1.44 — one per PHQ-9 / GAD-7 / WHO-5 with at least one administration. Absent on older servers.
+          type: array
+          items:
+            $ref: "#/components/schemas/MentalHealthAssessmentTrend"
       required:
         - assessments
       additionalProperties: false
@@ -74971,6 +74976,99 @@ components:
         diagnosis). `item9Flagged` is true when the PHQ-9 self-harm item was answered > 0 — the client MUST show crisis
         resources when it is. Raw per-item answers are intentionally absent from list rows; the by-id detail read
         returns them decrypted.
+    MentalHealthAssessmentTrend:
+      type: object
+      properties:
+        instrument:
+          type: string
+          enum:
+            - PHQ9
+            - GAD7
+            - WHO5
+        n:
+          type: integer
+          minimum: -9007199254740991
+          maximum: 9007199254740991
+        threshold:
+          type: number
+          description: "Meaningful-change threshold in reported points: PHQ-9 5, GAD-7 4, WHO-5 10 (0–100 scale)."
+        higherIsBetter:
+          type: boolean
+        first:
+          type: object
+          properties:
+            score:
+              type: number
+            takenAt:
+              type: string
+          required:
+            - score
+            - takenAt
+          additionalProperties: false
+        previous:
+          anyOf:
+            - type: object
+              properties:
+                score:
+                  type: number
+                takenAt:
+                  type: string
+              required:
+                - score
+                - takenAt
+              additionalProperties: false
+            - type: "null"
+        latest:
+          type: object
+          properties:
+            score:
+              type: number
+            takenAt:
+              type: string
+          required:
+            - score
+            - takenAt
+          additionalProperties: false
+        changeFromPrevious:
+          type:
+            - number
+            - "null"
+        changeFromFirst:
+          type:
+            - number
+            - "null"
+        sincePrevious:
+          anyOf:
+            - type: string
+              enum:
+                - improved
+                - worsened
+                - within_threshold
+            - type: "null"
+        sinceFirst:
+          anyOf:
+            - type: string
+              enum:
+                - improved
+                - worsened
+                - within_threshold
+            - type: "null"
+      required:
+        - instrument
+        - n
+        - threshold
+        - higherIsBetter
+        - first
+        - previous
+        - latest
+        - changeFromPrevious
+        - changeFromFirst
+        - sincePrevious
+        - sinceFirst
+      additionalProperties: false
+      description: v1.44 — the latest total against the previous and the first administration, classified against the
+        instrument's meaningful-change threshold in its own direction. A change below the threshold is
+        `within_threshold`. Server-computed over the whole history, not the page.
     CreateMentalHealthAssessmentEnvelope:
       type: object
       properties:
diff --git a/messages/de.json b/messages/de.json
index fc61d1d46..7fa10ef44 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Details anzeigen",
     "historyLoadError": "Dein Testverlauf konnte nicht geladen werden",
     "historyLoadErrorHint": "Das heißt nicht, dass keine Ergebnisse vorliegen. Die Liste konnte nicht abgerufen werden. Versuche es erneut.",
-    "privacyNote": "Deine Antworten sind verschlüsselt gespeichert und erreichen den KI-Coach nicht."
+    "privacyNote": "Deine Antworten sind verschlüsselt gespeichert und erreichen den KI-Coach nicht.",
+    "trend": {
+      "sincePrevious": "Seit deinem vorigen Check-in am {date}: {change} Punkte.",
+      "sinceFirst": "Seit deinem ersten Check-in am {date}: {change} Punkte.",
+      "verdict": {
+        "improved": "Das erreicht die Veränderung von {threshold} Punkten, die Studien als bedeutsam ansehen, in die bessere Richtung.",
+        "worsened": "Das erreicht die Veränderung von {threshold} Punkten, die Studien als bedeutsam ansehen, in die weniger gute Richtung.",
+        "within_threshold": "Das ist weniger als die Veränderung von {threshold} Punkten, die Studien als bedeutsam ansehen."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/en.json b/messages/en.json
index be2db6114..3e8a2fd08 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Show details",
     "historyLoadError": "Your assessment history could not be loaded",
     "historyLoadErrorHint": "This does not mean you have no results; the list could not be fetched. Try again.",
-    "privacyNote": "Your answers are stored encrypted and never reach the AI Coach."
+    "privacyNote": "Your answers are stored encrypted and never reach the AI Coach.",
+    "trend": {
+      "sincePrevious": "Since your previous check-in on {date}: {change} points.",
+      "sinceFirst": "Since your first check-in on {date}: {change} points.",
+      "verdict": {
+        "improved": "That reaches the {threshold}-point change studies treat as meaningful, in the better direction.",
+        "worsened": "That reaches the {threshold}-point change studies treat as meaningful, in the less good direction.",
+        "within_threshold": "That is smaller than the {threshold}-point change studies treat as meaningful."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/es.json b/messages/es.json
index 287b36a61..74d46bd52 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Ver detalles",
     "historyLoadError": "No se pudo cargar tu historial de evaluaciones",
     "historyLoadErrorHint": "Esto no significa que no tengas resultados: no se pudo obtener la lista. Vuelve a intentarlo.",
-    "privacyNote": "Tus respuestas se guardan cifradas y nunca llegan al Coach de IA."
+    "privacyNote": "Tus respuestas se guardan cifradas y nunca llegan al Coach de IA.",
+    "trend": {
+      "sincePrevious": "Desde tu revisión anterior del {date}: {change} puntos.",
+      "sinceFirst": "Desde tu primera revisión del {date}: {change} puntos.",
+      "verdict": {
+        "improved": "Alcanza el cambio de {threshold} puntos que los estudios consideran relevante, en la dirección favorable.",
+        "worsened": "Alcanza el cambio de {threshold} puntos que los estudios consideran relevante, en la dirección menos favorable.",
+        "within_threshold": "Es menor que el cambio de {threshold} puntos que los estudios consideran relevante."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/fr.json b/messages/fr.json
index d1c564694..b5fe83be3 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Voir les détails",
     "historyLoadError": "Ton historique d'évaluations n'a pas pu être chargé",
     "historyLoadErrorHint": "Cela ne veut pas dire que tu n'as aucun résultat : la liste n'a pas pu être récupérée. Réessaie.",
-    "privacyNote": "Vos réponses sont stockées chiffrées et n'atteignent jamais le Coach IA."
+    "privacyNote": "Vos réponses sont stockées chiffrées et n'atteignent jamais le Coach IA.",
+    "trend": {
+      "sincePrevious": "Depuis ton bilan précédent du {date} : {change} points.",
+      "sinceFirst": "Depuis ton premier bilan du {date} : {change} points.",
+      "verdict": {
+        "improved": "Cela atteint la variation de {threshold} points que les études jugent significative, dans le bon sens.",
+        "worsened": "Cela atteint la variation de {threshold} points que les études jugent significative, dans le sens moins favorable.",
+        "within_threshold": "C'est moins que la variation de {threshold} points que les études jugent significative."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/it.json b/messages/it.json
index dd0c39841..d4b271a51 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Mostra dettagli",
     "historyLoadError": "Non è stato possibile caricare la cronologia dei test",
     "historyLoadErrorHint": "Questo non significa che non ci siano risultati: non è stato possibile recuperare l'elenco. Riprova.",
-    "privacyNote": "Le tue risposte sono salvate cifrate e non raggiungono mai il Coach IA."
+    "privacyNote": "Le tue risposte sono salvate cifrate e non raggiungono mai il Coach IA.",
+    "trend": {
+      "sincePrevious": "Dal tuo check-in precedente del {date}: {change} punti.",
+      "sinceFirst": "Dal tuo primo check-in del {date}: {change} punti.",
+      "verdict": {
+        "improved": "Raggiunge la variazione di {threshold} punti che gli studi considerano rilevante, nella direzione migliore.",
+        "worsened": "Raggiunge la variazione di {threshold} punti che gli studi considerano rilevante, nella direzione meno buona.",
+        "within_threshold": "È meno della variazione di {threshold} punti che gli studi considerano rilevante."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/ko.json b/messages/ko.json
index f8ac7397c..80faf9d15 100644
--- a/messages/ko.json
+++ b/messages/ko.json
@@ -11075,7 +11075,16 @@
     "openDetail": "자세히 보기",
     "historyLoadError": "검사 기록을 불러오지 못했어요",
     "historyLoadErrorHint": "결과가 없다는 뜻은 아니에요. 목록을 가져오지 못했을 뿐이에요. 다시 시도해 주세요.",
-    "privacyNote": "답변은 암호화되어 저장되고, AI 코치에게는 전달되지 않아요."
+    "privacyNote": "답변은 암호화되어 저장되고, AI 코치에게는 전달되지 않아요.",
+    "trend": {
+      "sincePrevious": "{date} 이전 체크인 이후: {change}점.",
+      "sinceFirst": "{date} 첫 체크인 이후: {change}점.",
+      "verdict": {
+        "improved": "연구에서 의미 있다고 보는 {threshold}점 변화에 도달했고, 좋아지는 방향입니다.",
+        "worsened": "연구에서 의미 있다고 보는 {threshold}점 변화에 도달했고, 덜 좋은 방향입니다.",
+        "within_threshold": "연구에서 의미 있다고 보는 {threshold}점 변화보다 작습니다."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/nl.json b/messages/nl.json
index bc81ba2ae..e4bf20265 100644
--- a/messages/nl.json
+++ b/messages/nl.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Details tonen",
     "historyLoadError": "Je testgeschiedenis kon niet worden geladen",
     "historyLoadErrorHint": "Dit betekent niet dat je geen resultaten hebt; de lijst kon niet worden opgehaald. Probeer het opnieuw.",
-    "privacyNote": "Je antwoorden worden versleuteld opgeslagen en komen nooit bij de AI-coach terecht."
+    "privacyNote": "Je antwoorden worden versleuteld opgeslagen en komen nooit bij de AI-coach terecht.",
+    "trend": {
+      "sincePrevious": "Sinds je vorige check-in op {date}: {change} punten.",
+      "sinceFirst": "Sinds je eerste check-in op {date}: {change} punten.",
+      "verdict": {
+        "improved": "Dat bereikt de verandering van {threshold} punten die studies als betekenisvol zien, in de betere richting.",
+        "worsened": "Dat bereikt de verandering van {threshold} punten die studies als betekenisvol zien, in de minder goede richting.",
+        "within_threshold": "Dat is minder dan de verandering van {threshold} punten die studies als betekenisvol zien."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/messages/pl.json b/messages/pl.json
index 3939cf2eb..8913a25f1 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -11075,7 +11075,16 @@
     "openDetail": "Pokaż szczegóły",
     "historyLoadError": "Nie udało się wczytać historii testów",
     "historyLoadErrorHint": "To nie znaczy, że nie masz wyników; nie udało się pobrać listy. Spróbuj ponownie.",
-    "privacyNote": "Twoje odpowiedzi są przechowywane w postaci zaszyfrowanej i nigdy nie trafiają do Coacha AI."
+    "privacyNote": "Twoje odpowiedzi są przechowywane w postaci zaszyfrowanej i nigdy nie trafiają do Coacha AI.",
+    "trend": {
+      "sincePrevious": "Od poprzedniego sprawdzenia {date}: {change} pkt.",
+      "sinceFirst": "Od pierwszego sprawdzenia {date}: {change} pkt.",
+      "verdict": {
+        "improved": "To osiąga zmianę o {threshold} pkt, którą badania uznają za istotną, w lepszym kierunku.",
+        "worsened": "To osiąga zmianę o {threshold} pkt, którą badania uznają za istotną, w mniej korzystnym kierunku.",
+        "within_threshold": "To mniej niż zmiana o {threshold} pkt, którą badania uznają za istotną."
+      }
+    }
   },
   "records": {
     "aiInclusion": {
diff --git a/src/__tests__/analysis-depth-no-ai-guard.test.ts b/src/__tests__/analysis-depth-no-ai-guard.test.ts
index f5aa84195..b3b9e4067 100644
--- a/src/__tests__/analysis-depth-no-ai-guard.test.ts
+++ b/src/__tests__/analysis-depth-no-ai-guard.test.ts
@@ -30,6 +30,7 @@ const ANALYSIS_MODULES = [
   "lib/insights/discovery-matrix.ts",
   "lib/insights/derived/changepoint.ts",
   "lib/labs/lab-trend.ts",
+  "lib/mental-health/assessment-trend.ts",
 ] as const;
 
 /** Reachable under `lib/ai/` without being a model: the at-rest cipher. */
diff --git a/src/app/api/mental-health/assessments/__tests__/route.test.ts b/src/app/api/mental-health/assessments/__tests__/route.test.ts
index 715d25a99..3dfa8ded0 100644
--- a/src/app/api/mental-health/assessments/__tests__/route.test.ts
+++ b/src/app/api/mental-health/assessments/__tests__/route.test.ts
@@ -479,4 +479,50 @@ describe("GET /api/mental-health/assessments", () => {
       .calls[0][0] as { orderBy: unknown };
     expect(findArgs.orderBy).toEqual([{ takenAt: "desc" }, { id: "desc" }]);
   });
+
+  it("carries each screener's change against its meaningful-change threshold (v1.44)", async () => {
+    const at = (d: string) => new Date(`${d}T09:00:00.000Z`);
+    const history = [
+      {
+        id: "p2",
+        instrument: "PHQ9",
+        totalScore: 8,
+        takenAt: at("2026-06-01"),
+      },
+      {
+        id: "p1",
+        instrument: "PHQ9",
+        totalScore: 15,
+        takenAt: at("2026-02-01"),
+      },
+    ];
+    vi.mocked(prisma.mentalHealthAssessment.findMany)
+      .mockResolvedValueOnce([] as never)
+      .mockResolvedValueOnce(history as never);
+    const res = await (GET as unknown as (r: NextRequest) => Promise<Response>)(
+      new NextRequest(
+        new URL("http://localhost/api/mental-health/assessments?limit=1"),
+      ),
+    );
+    const body = await res.json();
+    expect(body.data.trends).toEqual([
+      expect.objectContaining({
+        instrument: "PHQ9",
+        n: 2,
+        threshold: 5,
+        changeFromPrevious: -7,
+        sincePrevious: "improved",
+      }),
+    ]);
+    // The trend read selects totals and dates only, never the answers.
+    const trendArgs = vi.mocked(prisma.mentalHealthAssessment.findMany).mock
+      .calls[1][0] as { select: Record<string, boolean>; where: unknown };
+    expect(Object.keys(trendArgs.select).sort()).toEqual([
+      "id",
+      "instrument",
+      "takenAt",
+      "totalScore",
+    ]);
+    expect(trendArgs.where).toMatchObject({ deletedAt: null });
+  });
 });
diff --git a/src/app/api/mental-health/assessments/route.ts b/src/app/api/mental-health/assessments/route.ts
index 610bceab3..740ae8d0d 100644
--- a/src/app/api/mental-health/assessments/route.ts
+++ b/src/app/api/mental-health/assessments/route.ts
@@ -58,6 +58,16 @@ import type {
   MeasurementSource,
 } from "@/generated/prisma/client";
 import { apiListSuccess } from "@/lib/api/list-cap";
+import {
+  computeAssessmentTrends,
+  TREND_INSTRUMENTS,
+} from "@/lib/mental-health/assessment-trend";
+
+/**
+ * Upper bound on administrations the trends read; years of weekly check-ins
+ * across three instruments stay far below it. The cap falls on the oldest.
+ */
+const TREND_READ_CAP = 1500;
 import { listPage } from "@/lib/http/list-query";
 
 function shapeRow(row: {
@@ -149,11 +159,25 @@ export const GET = apiHandler(async (request: NextRequest) => {
       },
     }),
   );
+  // v1.44 — the change of each screener against its meaningful-change
+  // threshold, over the whole history rather than the page: totals and dates
+  // only, never an item answer.
+  const trendRows = await prisma.mentalHealthAssessment.findMany({
+    where: {
+      userId: user.id,
+      deletedAt: null,
+      instrument: { in: TREND_INSTRUMENTS },
+    },
+    orderBy: [{ takenAt: "desc" }, { id: "desc" }],
+    take: TREND_READ_CAP,
+    select: { id: true, instrument: true, totalScore: true, takenAt: true },
+  });
+  const trends = computeAssessmentTrends(trendRows);
   annotate({
     action: { name: "mental-health.list" },
-    meta: { count: rows.length },
+    meta: { count: rows.length, trends: trends.length },
   });
-  return apiListSuccess({ assessments: rows.map(shapeRow) }, cap);
+  return apiListSuccess({ assessments: rows.map(shapeRow), trends }, cap);
 });
 
 // `withIdempotency` lets a double-tap / retry re-send the same
diff --git a/src/components/mental-health/__tests__/assessment-trend-note.test.tsx b/src/components/mental-health/__tests__/assessment-trend-note.test.tsx
new file mode 100644
index 000000000..3c81d65ee
--- /dev/null
+++ b/src/components/mental-health/__tests__/assessment-trend-note.test.tsx
@@ -0,0 +1,65 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+
+import { I18nProvider } from "@/lib/i18n/context";
+import { primeLocales } from "@/__tests__/helpers/prime-locales";
+
+import { AssessmentTrendNote } from "../assessment-trend-note";
+import type { AssessmentTrendDto } from "../types";
+
+primeLocales("de");
+
+const TREND: AssessmentTrendDto = {
+  instrument: "PHQ9",
+  n: 3,
+  threshold: 5,
+  higherIsBetter: false,
+  first: { score: 16, takenAt: "2026-01-10T09:00:00.000Z" },
+  previous: { score: 12, takenAt: "2026-03-15T09:00:00.000Z" },
+  latest: { score: 9, takenAt: "2026-06-01T09:00:00.000Z" },
+  changeFromPrevious: -3,
+  changeFromFirst: -7,
+  sincePrevious: "within_threshold",
+  sinceFirst: "improved",
+};
+
+const render = (trend: AssessmentTrendDto, locale: "en" | "de" = "en") =>
+  renderToStaticMarkup(
+    <I18nProvider initialLocale={locale}>
+      <AssessmentTrendNote trend={trend} />
+    </I18nProvider>,
+  );
+
+describe("<AssessmentTrendNote>", () => {
+  it("states each change and whether it reaches the threshold", () => {
+    const html = render(TREND);
+    expect(html).toContain("-3 points");
+    expect(html).toContain("smaller than the 5-point change");
+    expect(html).toContain("-7 points");
+    expect(html).toContain('data-verdict="improved"');
+  });
+
+  it("shows a rise with its sign, in German with du", () => {
+    const html = render(
+      { ...TREND, n: 2, changeFromPrevious: 6, sincePrevious: "worsened" },
+      "de",
+    );
+    expect(html).toContain("Seit deinem vorigen Check-in");
+    expect(html).toContain("+6 Punkte");
+    expect(html).not.toContain("ersten");
+  });
+
+  it("is silent with a single check-in", () => {
+    expect(
+      render({
+        ...TREND,
+        n: 1,
+        previous: null,
+        changeFromPrevious: null,
+        changeFromFirst: null,
+        sincePrevious: null,
+        sinceFirst: null,
+      }),
+    ).toBe("");
+  });
+});
diff --git a/src/components/mental-health/assessment-trend-note.tsx b/src/components/mental-health/assessment-trend-note.tsx
new file mode 100644
index 000000000..f604ba1f1
--- /dev/null
+++ b/src/components/mental-health/assessment-trend-note.tsx
@@ -0,0 +1,58 @@
+"use client";
+
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
+
+import type { AssessmentTrendDto } from "./types";
+
+/**
+ * v1.44 — how the latest score compares with the previous check-in (and,
+ * from the third, with the first), against the change size studies treat as
+ * meaningful for this instrument. Every number and verdict is the server's;
+ * the wording stays neutral: a change, its size, and whether it reaches the
+ * threshold. No band words, no advice.
+ */
+export function AssessmentTrendNote({ trend }: { trend: AssessmentTrendDto }) {
+  const { t } = useTranslations();
+  const { date: formatDate, number } = useFormatters();
+  if (trend.previous === null || trend.changeFromPrevious === null) return null;
+
+  const signed = (delta: number) =>
+    delta > 0 ? `+${number(delta, 0)}` : number(delta, 0);
+  const line = (
+    key: "sincePrevious" | "sinceFirst",
+    at: string,
+    delta: number,
+    verdict: NonNullable<AssessmentTrendDto["sincePrevious"]>,
+  ) =>
+    `${t(`mentalHealth.trend.${key}`, {
+      date: formatDate(at),
+      change: signed(delta),
+    })} ${t(`mentalHealth.trend.verdict.${verdict}`, {
+      threshold: trend.threshold,
+    })}`;
+
+  return (
+    <div className="space-y-1 text-sm" data-slot="assessment-trend">
+      {trend.sincePrevious ? (
+        <p data-verdict={trend.sincePrevious}>
+          {line(
+            "sincePrevious",
+            trend.previous.takenAt,
+            trend.changeFromPrevious,
+            trend.sincePrevious,
+          )}
+        </p>
+      ) : null}
+      {trend.n >= 3 && trend.sinceFirst && trend.changeFromFirst !== null ? (
+        <p data-verdict={trend.sinceFirst}>
+          {line(
+            "sinceFirst",
+            trend.first.takenAt,
+            trend.changeFromFirst,
+            trend.sinceFirst,
+          )}
+        </p>
+      ) : null}
+    </div>
+  );
+}
diff --git a/src/components/mental-health/instrument-detail.tsx b/src/components/mental-health/instrument-detail.tsx
index fb1b2d36b..4e798ee49 100644
--- a/src/components/mental-health/instrument-detail.tsx
+++ b/src/components/mental-health/instrument-detail.tsx
@@ -21,16 +21,20 @@ import { relativeCalendarDate } from "@/lib/i18n/relative-time";
 import { INSTRUMENTS } from "@/lib/mental-health/instruments";
 
 import { AssessmentHistory } from "./assessment-history";
-import type { AssessmentRow, InstrumentId } from "./types";
+import type { AssessmentRow, AssessmentTrendDto, InstrumentId } from "./types";
+import { AssessmentTrendNote } from "./assessment-trend-note";
 
 export function InstrumentDetail({
   instrument,
   rows,
+  trend,
   onStart,
 }: {
   instrument: InstrumentId;
   /** ALL assessments; the pinned history filters to this instrument. */
   rows: AssessmentRow[];
+  /** v1.44 — the server's change against the meaningful-change threshold. */
+  trend?: AssessmentTrendDto;
   /** Start a check-in for this instrument (closes the host sheet). */
   onStart: () => void;
 }) {
@@ -75,6 +79,8 @@ export function InstrumentDetail({
         </div>
       )}
 
+      {trend ? <AssessmentTrendNote trend={trend} /> : null}
+
       {/* The Start action stays reachable here too — the detail is a calm
           reading surface, not a dead end. */}
       {canManageMind && (
diff --git a/src/components/mental-health/mental-wellbeing.tsx b/src/components/mental-health/mental-wellbeing.tsx
index 3919ed1e6..a6341fb47 100644
--- a/src/components/mental-health/mental-wellbeing.tsx
+++ b/src/components/mental-health/mental-wellbeing.tsx
@@ -45,6 +45,7 @@ import { InstrumentCard } from "./instrument-card";
 import { InstrumentDetail } from "./instrument-detail";
 import type {
   AssessmentRow,
+  AssessmentTrendDto,
   CreateResponse,
   InstrumentId,
   Phase,
@@ -81,9 +82,10 @@ export function MentalWellbeing() {
   } = useQuery({
     queryKey: queryKeys.mentalHealthAssessments(),
     queryFn: () =>
-      apiGetList<{ assessments: AssessmentRow[] }>(
-        "/api/mental-health/assessments",
-      ),
+      apiGetList<{
+        assessments: AssessmentRow[];
+        trends?: AssessmentTrendDto[];
+      }>("/api/mental-health/assessments"),
   });
   const history = historyPage?.data;
 
@@ -229,6 +231,9 @@ export function MentalWellbeing() {
               <InstrumentDetail
                 instrument={detailInstrument}
                 rows={history?.assessments ?? []}
+                trend={history?.trends?.find(
+                  (trend) => trend.instrument === detailInstrument,
+                )}
                 onStart={() => begin(detailInstrument)}
               />
             )}
diff --git a/src/components/mental-health/types.ts b/src/components/mental-health/types.ts
index 26d47f766..b5b679876 100644
--- a/src/components/mental-health/types.ts
+++ b/src/components/mental-health/types.ts
@@ -48,3 +48,18 @@ export interface CreateResponse {
   actionThreshold: number;
   crisis: CrisisSet | null;
 }
+
+/** v1.44 — `GET /api/mental-health/assessments` `trends[]` (`computeAssessmentTrends`). */
+export interface AssessmentTrendDto {
+  instrument: "PHQ9" | "GAD7" | "WHO5";
+  n: number;
+  threshold: number;
+  higherIsBetter: boolean;
+  first: { score: number; takenAt: string };
+  previous: { score: number; takenAt: string } | null;
+  latest: { score: number; takenAt: string };
+  changeFromPrevious: number | null;
+  changeFromFirst: number | null;
+  sincePrevious: "improved" | "worsened" | "within_threshold" | null;
+  sinceFirst: "improved" | "worsened" | "within_threshold" | null;
+}
diff --git a/src/lib/mental-health/__tests__/assessment-trend.test.ts b/src/lib/mental-health/__tests__/assessment-trend.test.ts
new file mode 100644
index 000000000..5af9791c0
--- /dev/null
+++ b/src/lib/mental-health/__tests__/assessment-trend.test.ts
@@ -0,0 +1,80 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  computeAssessmentTrends,
+  MEANINGFUL_CHANGE,
+  verdictForChange,
+} from "../assessment-trend";
+
+const row = (
+  id: string,
+  instrument: string,
+  totalScore: number,
+  day: string,
+) => ({
+  id,
+  instrument,
+  totalScore,
+  takenAt: new Date(`${day}T09:00:00.000Z`),
+});
+
+describe("meaningful-change thresholds", () => {
+  it("are the published minimal important differences", () => {
+    expect(MEANINGFUL_CHANGE).toEqual({ PHQ9: 5, GAD7: 4, WHO5: 10 });
+  });
+
+  it("classify in the instrument's direction, inclusive at the threshold", () => {
+    expect(verdictForChange(-5, 5, false)).toBe("improved");
+    expect(verdictForChange(-4, 5, false)).toBe("within_threshold");
+    expect(verdictForChange(5, 5, false)).toBe("worsened");
+    expect(verdictForChange(12, 10, true)).toBe("improved");
+    expect(verdictForChange(-10, 10, true)).toBe("worsened");
+  });
+});
+
+describe("computeAssessmentTrends", () => {
+  it("compares the latest score with the previous and the first", () => {
+    const trends = computeAssessmentTrends([
+      row("c", "PHQ9", 9, "2026-06-01"),
+      row("a", "PHQ9", 16, "2026-01-10"),
+      row("b", "PHQ9", 12, "2026-03-15"),
+      row("g", "GAD7", 10, "2026-03-15"),
+      row("h", "GAD7", 13, "2026-06-01"),
+      row("w", "WHO5", 44, "2026-06-01"),
+      row("s", "SCI", 20, "2026-06-01"),
+    ]);
+    expect(trends.map((t) => t.instrument)).toEqual(["PHQ9", "GAD7", "WHO5"]);
+    const [phq, gad, who] = trends;
+    expect(phq).toMatchObject({
+      n: 3,
+      threshold: 5,
+      changeFromPrevious: -3,
+      changeFromFirst: -7,
+      sincePrevious: "within_threshold",
+      sinceFirst: "improved",
+      first: { score: 16 },
+      latest: { score: 9 },
+    });
+    expect(gad).toMatchObject({
+      n: 2,
+      changeFromPrevious: 3,
+      sincePrevious: "within_threshold",
+    });
+    expect(who).toMatchObject({
+      n: 1,
+      previous: null,
+      changeFromPrevious: null,
+      sincePrevious: null,
+      sinceFirst: null,
+    });
+  });
+
+  it("orders same-day administrations by id", () => {
+    const [phq] = computeAssessmentTrends([
+      row("b", "PHQ9", 20, "2026-06-01"),
+      row("a", "PHQ9", 10, "2026-06-01"),
+    ]);
+    expect(phq.latest.score).toBe(20);
+    expect(phq.sincePrevious).toBe("worsened");
+  });
+});
diff --git a/src/lib/mental-health/assessment-trend.ts b/src/lib/mental-health/assessment-trend.ts
new file mode 100644
index 000000000..1922be139
--- /dev/null
+++ b/src/lib/mental-health/assessment-trend.ts
@@ -0,0 +1,134 @@
+/**
+ * v1.44 — screener change measured against the size studies treat as
+ * meaningful, instead of the last score on its own.
+ *
+ * A difference between two administrations is only worth naming when it is
+ * at least the instrument's minimal clinically important difference, which
+ * the primary literature puts at:
+ *
+ *   - PHQ-9: 5 points (Löwe, Unützer, Callahan, Perkins & Kroenke 2004,
+ *     Med Care 42(12):1194–1201).
+ *   - GAD-7: 4 points (Toussaint, Hüsing, Gumz et al. 2020, J Affect Disord
+ *     265:395–401).
+ *   - WHO-5: 10 points on the 0–100 percentage scale (Topp, Østergaard,
+ *     Søndergaard & Bech 2015, Psychother Psychosom 84(3):167–176).
+ *
+ * A change below the threshold reads as "within the threshold", not as
+ * better or worse; a change at or beyond it reads in the instrument's own
+ * direction (lower is better on PHQ-9 / GAD-7, higher on WHO-5). This is a
+ * description of the person's own scores, never a diagnosis and never a
+ * treatment response; the SCI has no published threshold of this kind and
+ * gets no trend. Pure; the read lives in the assessments route.
+ */
+import {
+  INSTRUMENTS,
+  type InstrumentId,
+} from "@/lib/mental-health/instruments";
+
+export const MEANINGFUL_CHANGE: Readonly<
+  Partial<Record<InstrumentId, number>>
+> = {
+  PHQ9: 5,
+  GAD7: 4,
+  WHO5: 10,
+};
+
+export const TREND_INSTRUMENTS = Object.keys(
+  MEANINGFUL_CHANGE,
+) as InstrumentId[];
+
+export type ChangeVerdict = "improved" | "worsened" | "within_threshold";
+
+export interface ScorePoint {
+  score: number;
+  takenAt: string;
+}
+
+export interface AssessmentTrend {
+  instrument: InstrumentId;
+  /** Administrations of this instrument on record. */
+  n: number;
+  /** The meaningful-change threshold, in the instrument's reported points. */
+  threshold: number;
+  higherIsBetter: boolean;
+  first: ScorePoint;
+  previous: ScorePoint | null;
+  latest: ScorePoint;
+  /** latest − previous; null with one administration. */
+  changeFromPrevious: number | null;
+  /** latest − first; null with one administration. */
+  changeFromFirst: number | null;
+  sincePrevious: ChangeVerdict | null;
+  sinceFirst: ChangeVerdict | null;
+}
+
+/** Classify a signed change against the threshold in the instrument's direction. */
+export function verdictForChange(
+  delta: number,
+  threshold: number,
+  higherIsBetter: boolean,
+): ChangeVerdict {
+  if (Math.abs(delta) < threshold) return "within_threshold";
+  return delta > 0 === higherIsBetter ? "improved" : "worsened";
+}
+
+/**
+ * One trend per instrument that has a threshold and at least one
+ * administration, in the instrument order. Rows may arrive in any order;
+ * they are ordered by `takenAt`, then `id`.
+ */
+export function computeAssessmentTrends(
+  rows: ReadonlyArray<{
+    id: string;
+    instrument: string;
+    totalScore: number;
+    takenAt: Date;
+  }>,
+): AssessmentTrend[] {
+  const out: AssessmentTrend[] = [];
+  for (const instrument of TREND_INSTRUMENTS) {
+    const threshold = MEANINGFUL_CHANGE[instrument] as number;
+    const series = rows
+      .filter(
+        (r) => r.instrument === instrument && Number.isFinite(r.totalScore),
+      )
+      .sort(
+        (a, b) =>
+          a.takenAt.getTime() - b.takenAt.getTime() || (a.id < b.id ? -1 : 1),
+      );
+    if (series.length === 0) continue;
+    const { higherIsBetter } = INSTRUMENTS[instrument];
+    const point = (r: (typeof series)[number]): ScorePoint => ({
+      score: r.totalScore,
+      takenAt: r.takenAt.toISOString(),
+    });
+    const latest = series[series.length - 1];
+    const previous = series.length > 1 ? series[series.length - 2] : null;
+    const first = series[0];
+    const changeFromPrevious = previous
+      ? latest.totalScore - previous.totalScore
+      : null;
+    const changeFromFirst =
+      series.length > 1 ? latest.totalScore - first.totalScore : null;
+    out.push({
+      instrument,
+      n: series.length,
+      threshold,
+      higherIsBetter,
+      first: point(first),
+      previous: previous ? point(previous) : null,
+      latest: point(latest),
+      changeFromPrevious,
+      changeFromFirst,
+      sincePrevious:
+        changeFromPrevious === null
+          ? null
+          : verdictForChange(changeFromPrevious, threshold, higherIsBetter),
+      sinceFirst:
+        changeFromFirst === null
+          ? null
+          : verdictForChange(changeFromFirst, threshold, higherIsBetter),
+    });
+  }
+  return out;
+}
diff --git a/src/lib/openapi/routes/mental-health.ts b/src/lib/openapi/routes/mental-health.ts
index b7b81e7d8..8a15fd8e7 100644
--- a/src/lib/openapi/routes/mental-health.ts
+++ b/src/lib/openapi/routes/mental-health.ts
@@ -100,8 +100,48 @@ const createResponse = z
   })
   .meta({ id: "CreateMentalHealthAssessmentResponse" });
 
+const scorePoint = z.object({
+  score: z.number(),
+  takenAt: z.string(),
+});
+const changeVerdict = z
+  .enum(["improved", "worsened", "within_threshold"])
+  .nullable();
+
+const assessmentTrend = z
+  .object({
+    instrument: z.enum(["PHQ9", "GAD7", "WHO5"]),
+    n: z.number().int(),
+    threshold: z
+      .number()
+      .describe(
+        "Meaningful-change threshold in reported points: PHQ-9 5, GAD-7 4, WHO-5 10 (0–100 scale).",
+      ),
+    higherIsBetter: z.boolean(),
+    first: scorePoint,
+    previous: scorePoint.nullable(),
+    latest: scorePoint,
+    changeFromPrevious: z.number().nullable(),
+    changeFromFirst: z.number().nullable(),
+    sincePrevious: changeVerdict,
+    sinceFirst: changeVerdict,
+  })
+  .meta({
+    id: "MentalHealthAssessmentTrend",
+    description:
+      "v1.44 — the latest total against the previous and the first administration, classified against the instrument's meaningful-change threshold in its own direction. A change below the threshold is `within_threshold`. Server-computed over the whole history, not the page.",
+  });
+
 const listResponse = z
-  .object({ assessments: z.array(assessmentRow) })
+  .object({
+    assessments: z.array(assessmentRow),
+    trends: z
+      .array(assessmentTrend)
+      .optional()
+      .describe(
+        "v1.44 — one per PHQ-9 / GAD-7 / WHO-5 with at least one administration. Absent on older servers.",
+      ),
+  })
   .meta({ id: "ListMentalHealthAssessmentsResponse" });
 
 const detailResponse = z