diff --git a/src/lib/ai/__tests__/weekly-report-schema.test.ts b/src/lib/ai/__tests__/weekly-report-schema.test.ts
new file mode 100644
index 000000000..f048d768e
--- /dev/null
+++ b/src/lib/ai/__tests__/weekly-report-schema.test.ts
@@ -0,0 +1,319 @@
+import { describe, it, expect } from "vitest";
+import {
+  aiInsightResponseSchema,
+  weeklyReportSchema,
+  storyboardAnnotationSchema,
+  storyboardAnnotationsSchema,
+  type AIInsightResponse,
+} from "../schema";
+import {
+  PROMPT_VERSION,
+  getStrictInsightsSystemPrompt,
+} from "../prompts/insight-generator";
+
+/**
+ * v1.4.20 phase B4 — Weekly Report + Storyboard Annotations schema +
+ * prompt validation.
+ *
+ * Acceptance covered here:
+ *   1. PROMPT_VERSION matches `^4\.20\.\d+$` and is `4.20.2` (B4 bump).
+ *   2. weeklyReportSchema enforces section caps (summary 10-800,
+ *      bullet ≤280, ≤5 bullets, dataQualityNotes optional ≤280).
+ *   3. storyboardAnnotationSchema enforces date / label / category /
+ *      detail; the array is capped at 20.
+ *   4. aiInsightResponseSchema treats both blocks as optional + nullable
+ *      so legacy 4.20.1 caches round-trip.
+ *   5. EN + DE prompts both contain GROUND RULE 10 (weeklyReport) +
+ *      GROUND RULE 11 (storyboardAnnotations) with conservative
+ *      phrasing + section-name match.
+ */
+
+const baseResponse: AIInsightResponse = {
+  summary: "Things are trending well this week.",
+  recommendations: [],
+  citations: [],
+  warnings: [],
+};
+
+describe("PROMPT_VERSION (B4 bump)", () => {
+  it("is on the 4.20.x train", () => {
+    expect(PROMPT_VERSION).toMatch(/^4\.20\.\d+$/);
+  });
+
+  it("is bumped past 4.20.1 to signal weeklyReport + storyboardAnnotations", () => {
+    expect(PROMPT_VERSION).toBe("4.20.2");
+  });
+});
+
+describe("weeklyReportSchema", () => {
+  const validReport = {
+    weekISO: "2026-W19",
+    summary:
+      "Strong week — BP held under 130/85 on 9 of 10 readings and weight is down 0.6 kg.",
+    goingWell: [
+      "BP under 130/85 on 9 of 10 readings.",
+      "Weight down 0.6 kg this week.",
+      "Compliance 94 % over the past 7 days.",
+    ],
+    worthWatching: ["Monday-morning systolic +6 mmHg over 6 weeks."],
+    tips: ["Consider a brief walk after dinner on Mondays."],
+  };
+
+  it("accepts a fully-populated report", () => {
+    expect(weeklyReportSchema.safeParse(validReport).success).toBe(true);
+  });
+
+  it("accepts a report with optional dataQualityNotes", () => {
+    const result = weeklyReportSchema.safeParse({
+      ...validReport,
+      dataQualityNotes: "Only 5 BP readings this week — n is borderline.",
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects a malformed weekISO", () => {
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, weekISO: "2026-W9" })
+        .success,
+    ).toBe(false);
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, weekISO: "2026/W19" })
+        .success,
+    ).toBe(false);
+  });
+
+  it("rejects a summary < 10 chars", () => {
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, summary: "short" })
+        .success,
+    ).toBe(false);
+  });
+
+  it("rejects a summary > 800 chars", () => {
+    const tooLong = "x".repeat(801);
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, summary: tooLong })
+        .success,
+    ).toBe(false);
+  });
+
+  it("rejects a goingWell entry > 280 chars", () => {
+    const tooLong = "x".repeat(281);
+    expect(
+      weeklyReportSchema.safeParse({
+        ...validReport,
+        goingWell: [tooLong],
+      }).success,
+    ).toBe(false);
+  });
+
+  it("rejects more than 5 entries in any bullet list", () => {
+    const six = ["a", "b", "c", "d", "e", "f"];
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, goingWell: six })
+        .success,
+    ).toBe(false);
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, worthWatching: six })
+        .success,
+    ).toBe(false);
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, tips: six }).success,
+    ).toBe(false);
+  });
+
+  it("accepts empty bullet arrays (a quiet week is allowed)", () => {
+    const result = weeklyReportSchema.safeParse({
+      ...validReport,
+      goingWell: [],
+      worthWatching: [],
+      tips: [],
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects empty strings in bullet arrays", () => {
+    expect(
+      weeklyReportSchema.safeParse({ ...validReport, goingWell: [""] })
+        .success,
+    ).toBe(false);
+  });
+});
+
+describe("storyboardAnnotationSchema", () => {
+  const valid = {
+    date: "2026-04-14",
+    label: "Started Ramipril 5 mg",
+    category: "medication" as const,
+    detail:
+      "Logged a new medication entry on April 14. Average systolic for the prior 7 days was 146 mmHg.",
+  };
+
+  it("accepts a fully-formed entry", () => {
+    expect(storyboardAnnotationSchema.safeParse(valid).success).toBe(true);
+  });
+
+  it("rejects a malformed date", () => {
+    expect(
+      storyboardAnnotationSchema.safeParse({ ...valid, date: "April 14" })
+        .success,
+    ).toBe(false);
+    expect(
+      storyboardAnnotationSchema.safeParse({ ...valid, date: "2026-4-14" })
+        .success,
+    ).toBe(false);
+  });
+
+  it("rejects an unknown category", () => {
+    expect(
+      storyboardAnnotationSchema.safeParse({
+        ...valid,
+        category: "celebration" as never,
+      }).success,
+    ).toBe(false);
+  });
+
+  it("rejects a label > 80 chars", () => {
+    const tooLong = "x".repeat(81);
+    expect(
+      storyboardAnnotationSchema.safeParse({ ...valid, label: tooLong })
+        .success,
+    ).toBe(false);
+  });
+
+  it("rejects a detail > 400 chars", () => {
+    const tooLong = "x".repeat(401);
+    expect(
+      storyboardAnnotationSchema.safeParse({ ...valid, detail: tooLong })
+        .success,
+    ).toBe(false);
+  });
+
+  it("accepts each of the four canonical categories", () => {
+    for (const category of [
+      "medication",
+      "event",
+      "milestone",
+      "warning",
+    ] as const) {
+      expect(
+        storyboardAnnotationSchema.safeParse({ ...valid, category }).success,
+      ).toBe(true);
+    }
+  });
+
+  it("array form caps at 20 entries", () => {
+    const entry = valid;
+    const ok = Array.from({ length: 20 }, () => entry);
+    const tooMany = Array.from({ length: 21 }, () => entry);
+    expect(storyboardAnnotationsSchema.safeParse(ok).success).toBe(true);
+    expect(storyboardAnnotationsSchema.safeParse(tooMany).success).toBe(false);
+  });
+});
+
+describe("aiInsightResponseSchema — weeklyReport + storyboardAnnotations", () => {
+  it("legacy payload (no weeklyReport / storyboardAnnotations) still parses", () => {
+    expect(aiInsightResponseSchema.safeParse(baseResponse).success).toBe(true);
+  });
+
+  it("payload with weeklyReport=null parses", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      weeklyReport: null,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("payload with a populated weeklyReport parses round-trip", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      weeklyReport: {
+        weekISO: "2026-W19",
+        summary: "Things look good — BP held in target on 9 of 10 readings.",
+        goingWell: ["Compliance 94 %."],
+        worthWatching: [],
+        tips: ["Keep the evening dose at the same time each day."],
+      },
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.weeklyReport?.weekISO).toBe("2026-W19");
+    }
+  });
+
+  it("payload with storyboardAnnotations parses round-trip", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      storyboardAnnotations: [
+        {
+          date: "2026-04-14",
+          label: "Started Ramipril 5 mg",
+          category: "medication",
+          detail: "Logged on April 14. 7-day avg systolic prior was 146 mmHg.",
+        },
+      ],
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.storyboardAnnotations?.length).toBe(1);
+    }
+  });
+
+  it("payload with both blocks parses round-trip", () => {
+    const result = aiInsightResponseSchema.safeParse({
+      ...baseResponse,
+      weeklyReport: {
+        weekISO: "2026-W19",
+        summary: "Things look good across the board this week.",
+        goingWell: [],
+        worthWatching: [],
+        tips: [],
+      },
+      storyboardAnnotations: [],
+    });
+    expect(result.success).toBe(true);
+  });
+});
+
+describe("system prompt — GROUND RULE 10 (weeklyReport) + 11 (storyboardAnnotations)", () => {
+  it("English prompt declares the weeklyReport rule with section-name match", () => {
+    const prompt = getStrictInsightsSystemPrompt("en");
+    expect(prompt).toContain("weeklyReport");
+    expect(prompt).toMatch(/weekISO/);
+    expect(prompt).toContain("goingWell");
+    expect(prompt).toContain("worthWatching");
+    expect(prompt).toContain("tips");
+    expect(prompt).toContain("dataQualityNotes");
+    // Conservative phrasing reminder.
+    expect(prompt.toLowerCase()).toMatch(/no causal claims/);
+  });
+
+  it("English prompt declares the storyboardAnnotations rule", () => {
+    const prompt = getStrictInsightsSystemPrompt("en");
+    expect(prompt).toContain("storyboardAnnotations");
+    expect(prompt).toMatch(/medication|event|milestone|warning/);
+    expect(prompt).toMatch(/YYYY-MM-DD/);
+    // Neutral / factual phrasing reminder.
+    expect(prompt.toLowerCase()).toMatch(/neutral|factual/);
+  });
+
+  it("German prompt declares both blocks", () => {
+    const prompt = getStrictInsightsSystemPrompt("de");
+    expect(prompt).toContain("weeklyReport");
+    expect(prompt).toContain("storyboardAnnotations");
+    expect(prompt).toMatch(/Kausalbehauptungen/);
+    expect(prompt).toContain("medication");
+    expect(prompt).toContain("milestone");
+  });
+
+  it("both prompts spell the JSON shape with the correct keys", () => {
+    for (const locale of ["en", "de"] as const) {
+      const prompt = getStrictInsightsSystemPrompt(locale);
+      expect(prompt).toMatch(/"weekISO":/);
+      expect(prompt).toMatch(/"goingWell":/);
+      expect(prompt).toMatch(/"worthWatching":/);
+      expect(prompt).toMatch(/"tips":/);
+      expect(prompt).toMatch(/"category":/);
+    }
+  });
+});
diff --git a/src/lib/ai/prompts/insight-generator.ts b/src/lib/ai/prompts/insight-generator.ts
index 79a7381a9..d2d660375 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 = "4.20.1" as const;
+export const PROMPT_VERSION = "4.20.2" as const;
 
 const SYSTEM_PROMPT_EN = `You are a clinical-context summariser for a personal health-log app.
 Prompt version: ${PROMPT_VERSION}.
@@ -128,6 +128,52 @@ GROUND RULES — ZERO HALLUCINATIONS
    the entire block (or set null) when no metric qualifies. Trend
    annotations are SHORT — they sit below charts and compete for
    attention with the chart itself; one tight sentence is the goal.
+10. v1.4.20 phase B4 — Optional "weeklyReport" block. When the snapshot
+    covers a full ISO week (sufficient signal across BP / weight /
+    mood / compliance), emit a top-level "weeklyReport" object with:
+      - weekISO: ISO week identifier in "YYYY-Www" format (e.g.
+        "2026-W19"). MUST match the week the snapshot covers.
+      - summary: 1-2 sentence TL;DR (10-800 chars). Conservative
+        phrasing, no causal claims, no diagnosis.
+      - goingWell: 0-5 short bullets (≤ 280 chars each) — what's
+        going well this week. Each bullet derives from a number in
+        the snapshot.
+      - worthWatching: 0-5 short bullets (≤ 280 chars each) — what
+        deserves attention. Observational ("Monday-morning systolic
+        +6 mmHg"), not causal ("Monday-morning systolic is caused by
+        short Sunday sleep").
+      - tips: 0-5 short bullets (≤ 280 chars each) — small actionable
+        nudges. Generic ("consider a brief walk after dinner");
+        clinical guidance belongs with the user's doctor.
+      - dataQualityNotes (optional, ≤ 280 chars): only when the
+        snapshot has gaps that materially limit the analysis (n<7
+        readings in the analysed window, recencyDays>14, coverage
+        gaps that bias comparison). Omit when data is fine.
+    Section names match the report layout exactly. Use conservative
+    phrasing throughout — NEVER make causal claims ("X is causing Y")
+    and NEVER prescribe ("you should start taking X"). When the
+    snapshot does not cover a full week or has nothing analysable,
+    omit "weeklyReport" or set it to null.
+11. v1.4.20 phase B4 — Optional "storyboardAnnotations" array (max 20).
+    When the 90-day BP timeline includes notable factual events the
+    user logged, emit annotations that pin to specific dates. Each
+    annotation MUST:
+      - cite a real event from the snapshot (a logged measurement
+        outlier, a medication start/dose change, a streak milestone,
+        a target hit). Do NOT invent events.
+      - use neutral, factual prose — "started Ramipril 5 mg" not
+        "improvement is due to Ramipril". The user reads the timeline
+        and forms their own causal hypothesis; you do not.
+      - assign a category that reflects the event:
+          * "medication" — started, stopped, or dose-changed a med
+          * "event"      — a notable measurement / outlier / streak
+          * "milestone"  — target hit, threshold crossed
+          * "warning"    — a deviation worth flagging conservatively
+      - carry a one-paragraph "detail" (≤ 400 chars) the chapter card
+        renders below the timeline.
+    Date format: "YYYY-MM-DD". Label cap: 80 chars. Detail cap:
+    400 chars. Hard array cap: 20. Omit the field entirely when the
+    timeline has no notable events.
 
 GUIDELINE TARGETS — generic, do NOT compute precise risk scores
 - Adult resting blood pressure (ESH/ESC 2024 generic): aim < 140/90
@@ -201,7 +247,23 @@ You MUST return JSON matching this schema exactly:
     "bp": "one sentence, ≤200 chars, observational",
     "weight": "one sentence, ≤200 chars, observational",
     "mood": "one sentence, ≤200 chars, observational"
-  }
+  },
+  "weeklyReport": {
+    "weekISO": "YYYY-Www (e.g. 2026-W19)",
+    "summary": "1-2 sentence TL;DR (10-800 chars), conservative phrasing",
+    "goingWell": ["≤280 char bullet", "..."],
+    "worthWatching": ["≤280 char bullet", "..."],
+    "tips": ["≤280 char bullet", "..."],
+    "dataQualityNotes": "≤280 chars, ONLY when data quality limits analysis"
+  },
+  "storyboardAnnotations": [
+    {
+      "date": "YYYY-MM-DD",
+      "label": "≤80 char neutral label (e.g. 'Started Ramipril 5 mg')",
+      "category": "medication | event | milestone | warning",
+      "detail": "≤400 char neutral detail paragraph"
+    }
+  ]
 }
 
 Every recommendation's metricSource (type + timeRange) MUST appear in
@@ -216,6 +278,14 @@ The trendAnnotations block is optional. Each metric (bp, weight, mood)
 is independently optional — emit only the metrics with usable signal.
 Each annotation is ONE sentence, observational, ≤ 200 chars.
 
+The weeklyReport block is optional. Omit it (or set to null) when the
+snapshot does not cover a full ISO week. Section names MUST match
+the layout exactly. Phrasing stays conservative — no causal claims.
+
+The storyboardAnnotations array is optional. Omit when the 90-day
+timeline has no notable factual events. Each entry pins to a real,
+user-logged event with a neutral label + detail. Hard cap 20 entries.
+
 LANGUAGE
 Respond in English. Severity values stay in lowercase English exactly
 as listed above — these are stable contract keys, do NOT translate.
@@ -330,6 +400,55 @@ GRUNDREGELN — NULL HALLUZINATIONEN
    Metrik qualifiziert. Trend-Annotationen sind KURZ — sie stehen unter
    Charts und konkurrieren mit dem Chart selbst um Aufmerksamkeit; ein
    prägnanter Satz ist das Ziel.
+10. v1.4.20 phase B4 — Optionaler "weeklyReport"-Block. Wenn der
+    Snapshot eine vollständige ISO-Woche abdeckt (genügend Signal
+    über BP / Gewicht / Stimmung / Compliance), emittiere ein Top-
+    Level-Objekt "weeklyReport" mit:
+      - weekISO: ISO-Wochen-ID im Format "YYYY-Www" (z.B. "2026-W19").
+        MUSS der Woche entsprechen, die der Snapshot abdeckt.
+      - summary: 1-2 Sätze TL;DR (10-800 Zeichen). Sachliche Sprache,
+        keine Kausalbehauptungen, keine Diagnose.
+      - goingWell: 0-5 kurze Stichpunkte (≤ 280 Zeichen) — was
+        diese Woche gut läuft. Jeder Stichpunkt stützt sich auf
+        eine Zahl im Snapshot.
+      - worthWatching: 0-5 kurze Stichpunkte (≤ 280 Zeichen) — was
+        Beachtung verdient. Beobachtend ("Montag-morgen-Systole
+        +6 mmHg"), nicht kausal ("Montag-morgen-Systole verursacht
+        durch kurzen Sonntagsschlaf").
+      - tips: 0-5 kurze Stichpunkte (≤ 280 Zeichen) — kleine
+        umsetzbare Anregungen. Generisch ("kleiner Spaziergang nach
+        dem Essen erwägen"); klinische Beratung gehört zum Arzt.
+      - dataQualityNotes (optional, ≤ 280 Zeichen): nur wenn der
+        Snapshot Lücken hat, die die Analyse substanziell
+        einschränken (n<7, recencyDays>14, Coverage-Lücken). Bei
+        ausreichender Datenlage weglassen.
+    Sektionsnamen entsprechen exakt dem Report-Layout. Sprache
+    durchgehend sachlich — KEINE Kausalbehauptungen ("X verursacht
+    Y") und KEINE Verschreibungen ("du solltest X einnehmen"). Wenn
+    der Snapshot keine vollständige Woche abdeckt oder nichts
+    Analysierbares enthält, lass "weeklyReport" weg oder setze null.
+11. v1.4.20 phase B4 — Optionales "storyboardAnnotations"-Array
+    (max 20). Wenn die 90-Tage-BP-Timeline bemerkenswerte vom Nutzer
+    geloggte Ereignisse enthält, emittiere Annotationen, die auf
+    konkrete Daten zeigen. Jede Annotation MUSS:
+      - sich auf ein reales Ereignis im Snapshot beziehen (ein
+        geloggter Messwert-Outlier, ein Medikamentenstart/-wechsel,
+        ein Streak-Meilenstein, ein erreichter Zielwert). Erfinde
+        KEINE Ereignisse.
+      - sachlich-neutral formulieren — "Ramipril 5 mg gestartet"
+        statt "Verbesserung ist auf Ramipril zurückzuführen". Der
+        Nutzer liest die Timeline und bildet seine eigene kausale
+        Hypothese; du nicht.
+      - eine category zuweisen, die das Ereignis spiegelt:
+          * "medication" — Medikament gestartet/gestoppt/Dosis geändert
+          * "event"      — bemerkenswerte Messung/Outlier/Streak
+          * "milestone"  — Zielwert erreicht, Schwelle überschritten
+          * "warning"    — Abweichung, die sachlich zu flaggen ist
+      - ein einzelnes "detail"-Paragraph (≤ 400 Zeichen) tragen, das
+        die Chapter-Karte unter der Timeline rendert.
+    Datumsformat: "YYYY-MM-DD". Label-Cap: 80 Zeichen. Detail-Cap:
+    400 Zeichen. Array-Höchstgrenze: 20. Lass das Feld komplett
+    weg, wenn die Timeline keine bemerkenswerten Ereignisse hat.
 
 LEITLINIEN-ZIELWERTE — generisch, KEINE genauen Risiko-Scores berechnen
 - Erwachsenen-Ruheblutdruck (ESH/ESC 2024 generisch): Ziel < 140/90
@@ -404,7 +523,23 @@ Du MUSST JSON exakt nach diesem Schema liefern:
     "bp": "ein Satz, ≤ 200 Zeichen, beobachtend",
     "weight": "ein Satz, ≤ 200 Zeichen, beobachtend",
     "mood": "ein Satz, ≤ 200 Zeichen, beobachtend"
-  }
+  },
+  "weeklyReport": {
+    "weekISO": "YYYY-Www (z.B. 2026-W19)",
+    "summary": "1-2 Sätze TL;DR (10-800 Zeichen), sachliche Sprache",
+    "goingWell": ["≤280 Zeichen Stichpunkt", "..."],
+    "worthWatching": ["≤280 Zeichen Stichpunkt", "..."],
+    "tips": ["≤280 Zeichen Stichpunkt", "..."],
+    "dataQualityNotes": "≤280 Zeichen, NUR wenn Datenqualität die Analyse einschränkt"
+  },
+  "storyboardAnnotations": [
+    {
+      "date": "YYYY-MM-DD",
+      "label": "≤80 Zeichen sachliches Label (z.B. 'Ramipril 5 mg gestartet')",
+      "category": "medication | event | milestone | warning",
+      "detail": "≤400 Zeichen sachlicher Detail-Paragraph"
+    }
+  ]
 }
 
 Jede metricSource (type + timeRange) einer Empfehlung MUSS in
@@ -420,6 +555,16 @@ Der trendAnnotations-Block ist optional. Jede Metrik (bp, weight, mood)
 ist unabhängig optional — emittiere nur Metriken mit nutzbarem Signal.
 Jede Annotation ist EIN Satz, beobachtend, ≤ 200 Zeichen.
 
+Der weeklyReport-Block ist optional. Lass ihn weg (oder setze null),
+wenn der Snapshot keine vollständige ISO-Woche abdeckt. Sektionsnamen
+MÜSSEN exakt dem Layout entsprechen. Sprache bleibt sachlich — keine
+Kausalbehauptungen.
+
+Das storyboardAnnotations-Array ist optional. Lass es weg, wenn die
+90-Tage-Timeline keine bemerkenswerten Ereignisse enthält. Jeder
+Eintrag verweist auf ein reales, vom Nutzer geloggtes Ereignis mit
+neutralem Label + Detail. Höchstgrenze: 20 Einträge.
+
 SPRACHE
 Antworte auf Deutsch. Severity-Werte bleiben exakt in englischer
 Kleinschreibung wie oben gelistet — das sind stabile Vertragsschlüssel
diff --git a/src/lib/ai/schema.ts b/src/lib/ai/schema.ts
index 1fe96c796..6d1b342af 100644
--- a/src/lib/ai/schema.ts
+++ b/src/lib/ai/schema.ts
@@ -315,6 +315,127 @@ export const trendAnnotationsSchema = z.object({
 
 export type TrendAnnotations = z.infer<typeof trendAnnotationsSchema>;
 
+/**
+ * v1.4.20 phase B4 — Weekly Report block.
+ *
+ * The newsletter-style printable report at `/insights/report/[week]`
+ * renders six sections off this payload: Summary, What's going well,
+ * What's worth watching, Tips, Data-quality notes (optional), plus the
+ * `weekISO` label that pins the report to a specific ISO week.
+ *
+ * Hard caps are deliberate so a runaway model cannot pad the surface:
+ *   - summary: 10..800 chars (TL;DR paragraph)
+ *   - goingWell / worthWatching / tips: each item ≤ 280 chars, ≤ 5 items
+ *   - dataQualityNotes: ≤ 280 chars, optional
+ *
+ * The block is `nullable().optional()` so cached payloads from before
+ * PROMPT_VERSION 4.20.2 round-trip without forcing a regenerate. Fresh
+ * generations after the bump emit the block when the snapshot covers
+ * a full ISO week.
+ */
+export const weeklyReportSchema = z.object({
+  /**
+   * ISO week identifier, e.g. "2026-W19". Format: `YYYY-Www` where ww is
+   * the two-digit ISO week number. The route's `[week]` param pins to
+   * the same key so the report URL matches the AI payload.
+   */
+  weekISO: z
+    .string()
+    .regex(/^\d{4}-W\d{2}$/, "weeklyReport.weekISO must match YYYY-Www"),
+  /** TL;DR paragraph — 1-2 sentences synthesising the week's signal. */
+  summary: z
+    .string()
+    .min(10, "weeklyReport.summary must be at least 10 chars")
+    .max(800, "weeklyReport.summary must be <= 800 chars"),
+  /** "Wins" — what's going well. Up to 5 short bullets. */
+  goingWell: z
+    .array(
+      z
+        .string()
+        .min(1, "weeklyReport.goingWell entry required")
+        .max(280, "weeklyReport.goingWell entry must be <= 280 chars"),
+    )
+    .max(5, "weeklyReport.goingWell can hold at most 5 entries"),
+  /** "Watchlist" — what's worth watching. Up to 5 short bullets. */
+  worthWatching: z
+    .array(
+      z
+        .string()
+        .min(1, "weeklyReport.worthWatching entry required")
+        .max(280, "weeklyReport.worthWatching entry must be <= 280 chars"),
+    )
+    .max(5, "weeklyReport.worthWatching can hold at most 5 entries"),
+  /** Tips — small actionable nudges. Up to 5 short bullets. */
+  tips: z
+    .array(
+      z
+        .string()
+        .min(1, "weeklyReport.tips entry required")
+        .max(280, "weeklyReport.tips entry must be <= 280 chars"),
+    )
+    .max(5, "weeklyReport.tips can hold at most 5 entries"),
+  /**
+   * Data-quality notes — surfaced only when the snapshot has gaps that
+   * materially limit the analysis (n<7, recencyDays>14, etc.). Optional
+   * because most weeks don't need a caveat.
+   */
+  dataQualityNotes: z
+    .string()
+    .max(280, "weeklyReport.dataQualityNotes must be <= 280 chars")
+    .optional(),
+});
+
+export type WeeklyReport = z.infer<typeof weeklyReportSchema>;
+
+/**
+ * v1.4.20 phase B4 — Storyboard annotations.
+ *
+ * The 90-day BP timeline on `/insights` overlays factual events the user
+ * logged ("started medication X", "first sustained dip below 140") onto
+ * the chart as vertical reference lines + chapter cards beneath. Each
+ * annotation MUST cite a real event from the snapshot — the prose is
+ * neutral, never causal ("started medication X" not "improvement is due
+ * to X").
+ *
+ * Hard cap of 20 entries so a runaway model cannot blanket the chart
+ * with reference lines. The block itself is `.optional()` (no nullable
+ * wrap because zod treats an absent field as undefined for arrays
+ * uniformly).
+ */
+export const storyboardAnnotationSchema = z.object({
+  /** ISO date the annotation pins to (YYYY-MM-DD). */
+  date: z
+    .string()
+    .regex(
+      /^\d{4}-\d{2}-\d{2}$/,
+      "storyboardAnnotation.date must be YYYY-MM-DD",
+    ),
+  /** Short label rendered next to the reference line (≤ 80 chars). */
+  label: z
+    .string()
+    .min(1, "storyboardAnnotation.label required")
+    .max(80, "storyboardAnnotation.label must be <= 80 chars"),
+  /**
+   * Category drives the annotation colour:
+   *   - "medication" — Dracula pink (started/changed dose)
+   *   - "event"      — Dracula cyan (a notable user-logged event)
+   *   - "milestone"  — Dracula green (target hit, streak milestone)
+   *   - "warning"    — Dracula orange (a deviation worth flagging)
+   */
+  category: z.enum(["medication", "event", "milestone", "warning"]),
+  /** One-paragraph detail that the chapter card surfaces below the chart. */
+  detail: z
+    .string()
+    .min(1, "storyboardAnnotation.detail required")
+    .max(400, "storyboardAnnotation.detail must be <= 400 chars"),
+});
+
+export type StoryboardAnnotation = z.infer<typeof storyboardAnnotationSchema>;
+
+export const storyboardAnnotationsSchema = z
+  .array(storyboardAnnotationSchema)
+  .max(20, "storyboardAnnotations can hold at most 20 entries");
+
 /**
  * Canonical strict response schema. New strict fields are required;
  * legacy rich fields ride along through `.passthrough()` for back-
@@ -342,6 +463,18 @@ export const aiInsightResponseSchema = z
      * legacy 4.20.0 caches round-trip.
      */
     trendAnnotations: trendAnnotationsSchema.nullable().optional(),
+    /**
+     * v1.4.20 phase B4 — optional Weekly Report block. Nullable +
+     * optional so legacy cached payloads from before PROMPT_VERSION
+     * 4.20.2 round-trip without forcing a regenerate.
+     */
+    weeklyReport: weeklyReportSchema.nullable().optional(),
+    /**
+     * v1.4.20 phase B4 — optional storyboard annotations. Each entry
+     * pins a vertical reference line + chapter card to a date on the
+     * 90-day BP timeline. Optional so legacy caches round-trip.
+     */
+    storyboardAnnotations: storyboardAnnotationsSchema.optional(),
   })
   .passthrough();