diff --git a/src/lib/ai/__tests__/daily-briefing-schema.test.ts b/src/lib/ai/__tests__/daily-briefing-schema.test.ts
new file mode 100644
index 000000000..67548e1db
--- /dev/null
+++ b/src/lib/ai/__tests__/daily-briefing-schema.test.ts
@@ -0,0 +1,277 @@
+import { describe, it, expect } from "vitest";
+import {
+  aiInsightResponseSchema,
+  dailyBriefingKeyFindingSchema,
+  dailyBriefingSchema,
+  type AIInsightResponse,
+} from "../schema";
+import { PROMPT_VERSION } from "../prompts/insight-generator";
+
+/**
+ * v1.4.20 phase B1 — Daily Briefing schema validation.
+ *
+ * The Insights redesign hero strip + briefing card render a narrative
+ * paragraph + 0-5 key findings. The schema is `nullable().optional()`
+ * on the response so legacy v1.4.19 cached payloads round-trip without
+ * forcing a regenerate. Fresh generations after PROMPT_VERSION 4.20.0
+ * emit the block.
+ *
+ * Acceptance covered here:
+ *   1. Legacy payload (no `dailyBriefing` field at all) parses.
+ *   2. Well-formed Daily Briefing parses round-trip.
+ *   3. > 5 findings is rejected (hard cap so the model can't pad).
+ *   4. Empty paragraph is rejected (briefing card never paints void).
+ *   5. Each key finding requires headline + detail (no placeholders).
+ *   6. PROMPT_VERSION matches `^4\.20\.\d+$`.
+ */
+
+const baseFinding = {
+  tone: "good" as const,
+  headline: "Blood pressure entered target",
+  detail: "9 of last 10 readings under 130/85.",
+  delta: "↓ 4 mmHg",
+  sourceWindow: "30d" as const,
+  sourceMetric: "bp" as const,
+};
+
+const baseBriefing = {
+  paragraph:
+    "You're trending well this week — blood pressure is settling into your target band " +
+    "for the first time since February. Three things stand out: medication compliance " +
+    "is a 21-day streak, weight is down 2.5 kg over 30 days, and the mood-vs-pulse " +
+    "correlation that worried you in March has weakened. One thing to watch: morning " +
+    "systolic is still 6 mmHg above target on Mondays.",
+  keyFindings: [
+    baseFinding,
+    {
+      tone: "watch" as const,
+      headline: "Monday-morning systolic spike",
+      detail: "+6 mmHg vs other weekdays. Often follows late Sunday sleep.",
+      delta: "+6 mmHg",
+      sourceWindow: "30d" as const,
+      sourceMetric: "bp" as const,
+    },
+    {
+      tone: "info" as const,
+      headline: "Weight down 30 d",
+      detail: "Linear, sustainable rate. BMI is now 26.0.",
+      delta: "−2.5 kg",
+      sourceWindow: "30d" as const,
+      sourceMetric: "weight" as const,
+    },
+  ],
+};
+
+const baseResponse: AIInsightResponse = {
+  summary: "Things are trending well this week.",
+  recommendations: [],
+  citations: [],
+  warnings: [],
+};
+
+describe("PROMPT_VERSION", () => {
+  it("matches the v1.4.20 series 4.20.x", () => {
+    expect(PROMPT_VERSION).toMatch(/^4\.20\.\d+$/);
+  });
+});
+
+describe("dailyBriefingKeyFindingSchema", () => {
+  it("accepts a well-formed finding", () => {
+    expect(dailyBriefingKeyFindingSchema.safeParse(baseFinding).success).toBe(
+      true,
+    );
+  });
+
+  it.each(["good", "watch", "info"] as const)(
+    "accepts tone=%s",
+    (tone) => {
+      const result = dailyBriefingKeyFindingSchema.safeParse({
+        ...baseFinding,
+        tone,
+      });
+      expect(result.success).toBe(true);
+    },
+  );
+
+  it("rejects an unknown tone", () => {
+    const result = dailyBriefingKeyFindingSchema.safeParse({
+      ...baseFinding,
+      tone: "danger",
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it.each(["7d", "30d", "90d", "1y"] as const)(
+    "accepts sourceWindow=%s",
+    (sourceWindow) => {
+      const result = dailyBriefingKeyFindingSchema.safeParse({
+        ...baseFinding,
+        sourceWindow,
+      });
+      expect(result.success).toBe(true);
+    },
+  );
+
+  it("defaults sourceWindow to 30d when omitted", () => {
+    const { sourceWindow: _omit, ...withoutWindow } = baseFinding;
+    void _omit;
+    const result = dailyBriefingKeyFindingSchema.safeParse(withoutWindow);
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.sourceWindow).toBe("30d");
+    }
+  });
+
+  it.each(["bp", "weight", "pulse", "mood", "compliance"] as const)(
+    "accepts sourceMetric=%s",
+    (sourceMetric) => {
+      const result = dailyBriefingKeyFindingSchema.safeParse({
+        ...baseFinding,
+        sourceMetric,
+      });
+      expect(result.success).toBe(true);
+    },
+  );
+
+  it("rejects an unknown sourceMetric", () => {
+    const result = dailyBriefingKeyFindingSchema.safeParse({
+      ...baseFinding,
+      sourceMetric: "hrv",
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("accepts a null delta", () => {
+    const result = dailyBriefingKeyFindingSchema.safeParse({
+      ...baseFinding,
+      delta: null,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects empty headline", () => {
+    const result = dailyBriefingKeyFindingSchema.safeParse({
+      ...baseFinding,
+      headline: "",
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("rejects empty detail", () => {
+    const result = dailyBriefingKeyFindingSchema.safeParse({
+      ...baseFinding,
+      detail: "",
+    });
+    expect(result.success).toBe(false);
+  });
+});
+
+describe("dailyBriefingSchema", () => {
+  it("accepts a well-formed briefing", () => {
+    expect(dailyBriefingSchema.safeParse(baseBriefing).success).toBe(true);
+  });
+
+  it("rejects empty paragraph", () => {
+    const result = dailyBriefingSchema.safeParse({
+      ...baseBriefing,
+      paragraph: "",
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("accepts an empty keyFindings array", () => {
+    const result = dailyBriefingSchema.safeParse({
+      ...baseBriefing,
+      keyFindings: [],
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects > 5 keyFindings (hard cap)", () => {
+    const result = dailyBriefingSchema.safeParse({
+      ...baseBriefing,
+      keyFindings: [
+        baseFinding,
+        baseFinding,
+        baseFinding,
+        baseFinding,
+        baseFinding,
+        baseFinding,
+      ],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("accepts exactly 5 keyFindings (boundary)", () => {
+    const result = dailyBriefingSchema.safeParse({
+      ...baseBriefing,
+      keyFindings: [
+        baseFinding,
+        baseFinding,
+        baseFinding,
+        baseFinding,
+        baseFinding,
+      ],
+    });
+    expect(result.success).toBe(true);
+  });
+});
+
+describe("aiInsightResponseSchema — dailyBriefing integration", () => {
+  it("legacy payload (no dailyBriefing field) still parses", () => {
+    expect(aiInsightResponseSchema.safeParse(baseResponse).success).toBe(true);
+  });
+
+  it("payload with dailyBriefing=null still parses", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      dailyBriefing: null,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("payload with a well-formed dailyBriefing parses round-trip", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      dailyBriefing: baseBriefing,
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.dailyBriefing?.paragraph).toBe(baseBriefing.paragraph);
+      expect(result.data.dailyBriefing?.keyFindings).toHaveLength(3);
+    }
+  });
+
+  it("payload with > 5 keyFindings is rejected at the response level too", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      dailyBriefing: {
+        ...baseBriefing,
+        keyFindings: Array(6).fill(baseFinding),
+      },
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("payload with empty paragraph is rejected at the response level too", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      dailyBriefing: {
+        paragraph: "",
+        keyFindings: [],
+      },
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("payload with a finding missing required fields is rejected", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      dailyBriefing: {
+        paragraph: baseBriefing.paragraph,
+        keyFindings: [{ tone: "good", headline: "", detail: "x" }],
+      },
+    });
+    expect(result.success).toBe(false);
+  });
+});
diff --git a/src/lib/ai/prompts/insight-generator.ts b/src/lib/ai/prompts/insight-generator.ts
index a4943be14..fb1f7feb8 100644
--- a/src/lib/ai/prompts/insight-generator.ts
+++ b/src/lib/ai/prompts/insight-generator.ts
@@ -27,7 +27,7 @@ import {
 } from "../medical-references";
 
 /** Stable identifier for the active system prompt revision. */
-export const PROMPT_VERSION = "4.19.0" as const;
+export const PROMPT_VERSION = "4.20.0" as const;
 
 const SYSTEM_PROMPT_EN = `You are a clinical-context summariser for a personal health-log app.
 Prompt version: ${PROMPT_VERSION}.
@@ -93,6 +93,26 @@ GROUND RULES — ZERO HALLUCINATIONS
    patterns include "Your data foundation is strong", "Datengrundlage
    ist sehr stark", "You have a solid baseline", "Great dataset" and
    any rephrasing of the same sentiment.
+8. v1.4.20 — Optional "dailyBriefing" block. When the snapshot
+   carries enough signal (any of bp / weight / pulse / mood /
+   medications.compliance) emit a top-level "dailyBriefing" object
+   with two fields:
+     - paragraph: an 80-200 word narrative the user reads at the top
+       of /insights. Conservative phrasing, no diagnosis, no
+       prescription. Use the user's own data — do NOT extrapolate
+       to "people like you" or population norms. Avoid the banned
+       openers from rule 7.
+     - keyFindings: 0-5 short rows. Each row has tone (one of
+       "good" | "watch" | "info"), a headline (≤ 60 chars), a
+       one-sentence detail, an optional delta string (e.g.
+       "↓ 4 mmHg" or null), a sourceWindow (one of "7d" | "30d" |
+       "90d" | "1y"; default "30d") and a sourceMetric (one of
+       "bp" | "weight" | "pulse" | "mood" | "compliance"). Findings
+       MUST be derived from numbers in the snapshot. Five is the
+       hard cap — three is a healthier default.
+   When the snapshot has no analysable data, omit "dailyBriefing"
+   or set it to null. Empty paragraph or filler-only findings are
+   rejected by the parser.
 
 GUIDELINE TARGETS — generic, do NOT compute precise risk scores
 - Adult resting blood pressure (ESH/ESC 2024 generic): aim < 140/90
@@ -148,16 +168,35 @@ You MUST return JSON matching this schema exactly:
       "message": "what is flagged and why",
       "severity": "info" | "suggestion" | "important" | "urgent" (optional)
     }
-  ]
+  ],
+  "dailyBriefing": {
+    "paragraph": "80-200 word narrative grounded in this snapshot's numbers",
+    "keyFindings": [
+      {
+        "tone": "good | watch | info",
+        "headline": "≤60 char headline",
+        "detail": "one-sentence detail",
+        "delta": "optional delta string (e.g. '↓ 4 mmHg') or null",
+        "sourceWindow": "7d | 30d | 90d | 1y",
+        "sourceMetric": "bp | weight | pulse | mood | compliance"
+      }
+    ]
+  }
 }
 
 Every recommendation's metricSource (type + timeRange) MUST appear in
 citations[]. If two recommendations cite the same data point, list
 the citation once.
 
+The dailyBriefing block is optional. Omit it (or set to null) when the
+snapshot has nothing analysable. When present, paragraph MUST be
+non-empty and keyFindings MUST contain at most five entries.
+
 LANGUAGE
 Respond in English. Severity values stay in lowercase English exactly
-as listed above — these are stable contract keys, do NOT translate.`;
+as listed above — these are stable contract keys, do NOT translate.
+The dailyBriefing.tone, sourceWindow and sourceMetric values stay in
+lowercase English exactly as listed — also stable contract keys.`;
 
 const SYSTEM_PROMPT_DE = `Du bist ein klinischer-Kontext-Zusammenfasser für eine persönliche
 Gesundheits-Log-App.
@@ -227,6 +266,28 @@ GRUNDREGELN — NULL HALLUZINATIONEN
    Verbotene Eröffnungsmuster sind unter anderem "Datengrundlage ist
    sehr stark", "Your data foundation is strong", "Du hast eine solide
    Baseline", "Großartiger Datensatz" und jede sinngemäße Umformulierung.
+8. v1.4.20 — Optionaler "dailyBriefing"-Block. Wenn der Snapshot
+   genügend Signal trägt (irgendwas aus bp / weight / pulse / mood /
+   medications.compliance), emittiere ein Top-Level-Objekt
+   "dailyBriefing" mit zwei Feldern:
+     - paragraph: ein 80-200 Wörter langer Fließtext, den der Nutzer
+       oben auf /insights liest. Sachliche Sprache, keine Diagnose,
+       keine Verschreibung. Nutze die eigenen Daten des Nutzers —
+       extrapoliere NICHT auf "Menschen wie Sie" oder
+       Bevölkerungsnormen. Verwende keine in Regel 7 verbotenen
+       Eröffnungen.
+     - keyFindings: 0-5 kurze Zeilen. Jede Zeile hat tone (eines aus
+       "good" | "watch" | "info"), eine headline (≤ 60 Zeichen),
+       ein detail im Einzelsatz, einen optionalen delta-String
+       (z.B. "↓ 4 mmHg" oder null), ein sourceWindow (eines aus
+       "7d" | "30d" | "90d" | "1y"; Standard "30d") und ein
+       sourceMetric (eines aus "bp" | "weight" | "pulse" | "mood" |
+       "compliance"). Findings MÜSSEN aus Zahlen im Snapshot
+       abgeleitet sein. Fünf ist die harte Obergrenze — drei ist
+       der gesündere Standardwert.
+   Hat der Snapshot keine analysierbaren Daten, lass "dailyBriefing"
+   weg oder setze es auf null. Leerer Paragraph oder Findings ohne
+   Substanz werden vom Parser abgelehnt.
 
 LEITLINIEN-ZIELWERTE — generisch, KEINE genauen Risiko-Scores berechnen
 - Erwachsenen-Ruheblutdruck (ESH/ESC 2024 generisch): Ziel < 140/90
@@ -283,17 +344,37 @@ Du MUSST JSON exakt nach diesem Schema liefern:
       "message": "was wird geflaggt und warum",
       "severity": "info" | "suggestion" | "important" | "urgent" (optional)
     }
-  ]
+  ],
+  "dailyBriefing": {
+    "paragraph": "80-200 Wörter Fließtext, geerdet in den Zahlen dieses Snapshots",
+    "keyFindings": [
+      {
+        "tone": "good | watch | info",
+        "headline": "≤60 Zeichen Headline",
+        "detail": "ein Satz Detail",
+        "delta": "optionaler Delta-String (z.B. '↓ 4 mmHg') oder null",
+        "sourceWindow": "7d | 30d | 90d | 1y",
+        "sourceMetric": "bp | weight | pulse | mood | compliance"
+      }
+    ]
+  }
 }
 
 Jede metricSource (type + timeRange) einer Empfehlung MUSS in
 citations[] auftauchen. Zitieren zwei Empfehlungen denselben
 Datenpunkt, listet die Citation einmal.
 
+Der dailyBriefing-Block ist optional. Lass ihn weg (oder setze null),
+wenn der Snapshot nichts Analysierbares enthält. Wenn vorhanden, MUSS
+paragraph nicht leer sein und keyFindings höchstens fünf Einträge
+enthalten.
+
 SPRACHE
 Antworte auf Deutsch. Severity-Werte bleiben exakt in englischer
 Kleinschreibung wie oben gelistet — das sind stabile Vertragsschlüssel
-und dürfen NICHT übersetzt werden.`;
+und dürfen NICHT übersetzt werden. Auch dailyBriefing.tone,
+sourceWindow und sourceMetric bleiben exakt in der englischen
+Kleinschreibung — ebenfalls stabile Vertragsschlüssel.`;
 
 /**
  * Returns the active scope-hardened system prompt for a given locale.
diff --git a/src/lib/ai/schema.ts b/src/lib/ai/schema.ts
index 452aae2dd..c114ee5c0 100644
--- a/src/lib/ai/schema.ts
+++ b/src/lib/ai/schema.ts
@@ -215,6 +215,71 @@ export const aiWarningSchema = z.object({
 
 export type AIWarning = z.infer<typeof aiWarningSchema>;
 
+/**
+ * v1.4.20 phase B1 — Daily Briefing block.
+ *
+ * The Insights redesign hero strip + full-width briefing card render a
+ * narrative paragraph synthesised from the day's data plus up to five
+ * "key findings" — one-liners that summarise a single trend with a
+ * tone (good / watch / info), an optional delta string ("↓ 4 mmHg"),
+ * and the metric + window the finding was drawn from.
+ *
+ * The block is `nullable().optional()` so cached payloads from
+ * v1.4.19 (which predate the field) still parse cleanly. Fresh
+ * generations after the v1.4.20 PROMPT_VERSION bump emit the block.
+ *
+ * Marc's "zero hallucinations" mandate stays: the prompt instructs the
+ * model to derive every finding from a number visible in the snapshot,
+ * and `keyFindings.length` is hard-capped at 5 so a runaway model
+ * cannot pad the surface with filler.
+ */
+export const dailyBriefingKeyFindingSchema = z.object({
+  /**
+   * Tone drives the left-bar colour on the finding row:
+   *   - "good"  — Dracula green (target hit, streak, etc.)
+   *   - "watch" — Dracula orange (deviation worth noting)
+   *   - "info"  — Dracula cyan (neutral observation)
+   * Severity stays separate from the recommendation severity ladder
+   * so the briefing surface can be lighter-weight than the advisor.
+   */
+  tone: z.enum(["good", "watch", "info"]),
+  /** Headline — the one-liner the user reads first. */
+  headline: z.string().min(1, "keyFinding.headline required"),
+  /** One-sentence detail expanding on the headline. */
+  detail: z.string().min(1, "keyFinding.detail required"),
+  /**
+   * Optional delta string — e.g. "↓ 4 mmHg" or "+6 bpm". Null when the
+   * finding does not naturally carry a single delta (e.g. compliance
+   * streak: the "delta" is the streak length itself, captured in the
+   * detail).
+   */
+  delta: z.string().nullable(),
+  /** Window the finding was derived from — same enum as elsewhere. */
+  sourceWindow: z.enum(["7d", "30d", "90d", "1y"]).default("30d"),
+  /** Metric the finding was drawn from. */
+  sourceMetric: z.enum(["bp", "weight", "pulse", "mood", "compliance"]),
+});
+
+export type DailyBriefingKeyFinding = z.infer<
+  typeof dailyBriefingKeyFindingSchema
+>;
+
+export const dailyBriefingSchema = z.object({
+  /**
+   * Narrative paragraph — ~80-200 words. Synthesised from the day's
+   * data, conservative phrasing, no medical advice claims. Empty
+   * strings are rejected so the briefing card never paints a void.
+   */
+  paragraph: z.string().min(1, "dailyBriefing.paragraph required"),
+  /**
+   * 0-5 key findings. Empty array is acceptable when the data is
+   * truly flat; the hero strip simply hides the row in that case.
+   */
+  keyFindings: z.array(dailyBriefingKeyFindingSchema).min(0).max(5),
+});
+
+export type DailyBriefing = z.infer<typeof dailyBriefingSchema>;
+
 /**
  * Canonical strict response schema. New strict fields are required;
  * legacy rich fields ride along through `.passthrough()` for back-
@@ -230,6 +295,12 @@ export const aiInsightResponseSchema = z
     citations: z.array(aiCitationSchema),
     /** Guideline-flagged values (e.g. BP > 140/90). May be empty. */
     warnings: z.array(aiWarningSchema),
+    /**
+     * v1.4.20 phase B1 — optional Daily Briefing payload. Nullable +
+     * optional so legacy cached payloads (from before PROMPT_VERSION
+     * 4.20.0) round-trip without forcing a regenerate.
+     */
+    dailyBriefing: dailyBriefingSchema.nullable().optional(),
   })
   .passthrough();