diff --git a/src/lib/ai/prompts/__tests__/shared-contracts-coverage.test.ts b/src/lib/ai/prompts/__tests__/shared-contracts-coverage.test.ts
index e2c790a07..d9fc0f09a 100644
--- a/src/lib/ai/prompts/__tests__/shared-contracts-coverage.test.ts
+++ b/src/lib/ai/prompts/__tests__/shared-contracts-coverage.test.ts
@@ -67,11 +67,18 @@ const SURFACES: Record<
       forbiddenFiller,
     ],
   },
-  // The narrative is descriptive-only, so it enforces every contract EXCEPT
-  // the motivating tone contract.
+  // v1.21.0 (coach C1 MEDIUM-1) — the retrospective narrative now composes the
+  // shared tone contract too, so it matches the warm house voice of the daily
+  // briefing beside it. Its own descriptive-never-causal guards stay intact.
   "period-narrative": {
     prompt: (l) => SYSTEM_PROMPTS_FOR_TEST[l],
-    contracts: [grounding, safetyGlp1, metricIdentifierBan, forbiddenFiller],
+    contracts: [
+      grounding,
+      toneContract,
+      safetyGlp1,
+      metricIdentifierBan,
+      forbiddenFiller,
+    ],
   },
 };
 
diff --git a/src/lib/insights/narrative/__tests__/period-narrative-generate.test.ts b/src/lib/insights/narrative/__tests__/period-narrative-generate.test.ts
index 1ca917298..fa99fc7b3 100644
--- a/src/lib/insights/narrative/__tests__/period-narrative-generate.test.ts
+++ b/src/lib/insights/narrative/__tests__/period-narrative-generate.test.ts
@@ -25,6 +25,7 @@ import type {
   PeriodNarrativeContext,
   PeriodNarrativeResult,
 } from "@/lib/insights/narrative/period-narrative";
+import { toneContract } from "@/lib/ai/prompts/shared-contracts";
 
 function readyContext(
   over: Partial<PeriodNarrativeContext> = {},
@@ -170,6 +171,9 @@ describe("generatePeriodNarrative — descriptive generation", () => {
     });
     expect(systemPrompt).toMatch(/never CAUSAL|DESCRIPTIVE/);
     expect(systemPrompt).toMatch(/no markdown/i);
+    // v1.21.0 (coach C1 MEDIUM-1) — the retrospective now carries the shared
+    // warm tone contract verbatim, matching the briefing's house voice.
+    expect(systemPrompt).toContain(toneContract.en);
   });
 });
 
diff --git a/src/lib/insights/narrative/period-narrative-generate.ts b/src/lib/insights/narrative/period-narrative-generate.ts
index b597a5511..114855493 100644
--- a/src/lib/insights/narrative/period-narrative-generate.ts
+++ b/src/lib/insights/narrative/period-narrative-generate.ts
@@ -104,11 +104,11 @@ Hard rules:
 - The supplied CONTEXT is the ONLY source of truth. Never state a number, trend, driver, or threshold that is not in it.
 - Be DESCRIPTIVE, never CAUSAL. Say "X moved with Y" or "X was associated with Y", never "X caused Y" or "because of X".
 - The listed drivers already survived statistical multiple-comparison control; restate them only as associations and keep their conservative meaning.
-- No diagnosis, no medical advice, no alarm. Calm, factual, second person ("your").
+- No diagnosis, no medical advice, no alarm. Calm, factual, second person ("your"). When the period earned it, name one genuine win plainly; keep it warm and second-person, never a reflexive compliment.
 - 2 to 4 short sentences. Plain text only — no markdown, no headings, no bullet points, no emojis.
 - If the context is thin, say plainly that there is little to report this period rather than inventing detail.
 
-${composeSharedContracts("en", ["grounding", "safetyGlp1", "metricIdentifierBan", "forbiddenFiller"])}`;
+${composeSharedContracts("en", ["toneContract", "grounding", "safetyGlp1", "metricIdentifierBan", "forbiddenFiller"])}`;
 
 const SYSTEM_PROMPT_DE = `Du fasst den Gesundheits-Tracking-ZEITRAUM einer Person (eine Woche oder einen Monat) für diese Person zusammen.
 Prompt-Version: ${NARRATIVE_PROMPT_VERSION}.
@@ -117,11 +117,11 @@ Feste Regeln:
 - Der bereitgestellte KONTEXT ist die EINZIGE Wahrheitsquelle. Nenne nie eine Zahl, einen Trend, einen Zusammenhang oder einen Schwellenwert, der nicht darin steht.
 - Sei BESCHREIBEND, nie URSÄCHLICH. Sage "X bewegte sich mit Y" oder "X war mit Y assoziiert", nie "X verursachte Y" oder "wegen X".
 - Die genannten Zusammenhänge haben bereits die statistische Mehrfachvergleichskorrektur überstanden; gib sie nur als Assoziationen wieder und bewahre ihre vorsichtige Bedeutung.
-- Keine Diagnose, kein medizinischer Rat, keine Panik. Ruhig, sachlich, in der zweiten Person ("dein").
+- Keine Diagnose, kein medizinischer Rat, keine Panik. Ruhig, sachlich, in der zweiten Person ("dein"). Wenn der Zeitraum es hergibt, benenne einen echten Erfolg klar; bleib warm und in der zweiten Person, nie ein reflexhaftes Kompliment.
 - 2 bis 4 kurze Sätze. Nur Klartext — kein Markdown, keine Überschriften, keine Aufzählungen, keine Emojis.
 - Wenn der Kontext dünn ist, sage klar, dass es in diesem Zeitraum wenig zu berichten gibt, statt Details zu erfinden.
 
-${composeSharedContracts("de", ["grounding", "safetyGlp1", "metricIdentifierBan", "forbiddenFiller"])}`;
+${composeSharedContracts("de", ["toneContract", "grounding", "safetyGlp1", "metricIdentifierBan", "forbiddenFiller"])}`;
 
 /**
  * Test-only view of the composed system prompts (incl. the appended shared