fix(briefing): render briefing body into content so the model sees it

src/services/briefing-render.ts

@@ -0,0 +1,37 @@
+import type { BriefingOutput, BriefingSection } from "./home-types.ts";
+
+// Section categories in the order the model should read them — attention
+// first (matches the generator's "surface these first" guidance), then
+// recent activity, then what's coming up. Mirrors the schema enum in
+// `src/tools/platform/schemas/home.ts` (BriefingSection.category) — NOT the
+// stale names in the inline dashboard script.
+const CATEGORY_ORDER: { category: BriefingSection["category"]; label: string }[] = [
+  { category: "attention", label: "Needs attention" },
+  { category: "recent", label: "Recent" },
+  { category: "upcoming", label: "Coming up" },
+];
+
+/**
+ * Render a `BriefingOutput` as human-readable markdown for the `content`
+ * field of the `nb__briefing` tool result.
+ *
+ * The briefing body lives in `structuredContent` for the dashboard, but the
+ * model only ever sees `content` (the engine feeds `extractTextForModel(content)`
+ * back into the prompt — `structuredContent` never reaches it). A model-facing
+ * tool's `content` must therefore carry the human-readable summary, per the
+ * platform-tool contract (src/tools/platform/CLAUDE.md §2.1). Without this the
+ * model receives only the status note and reports an empty briefing.
+ */
+export function renderBriefingText(briefing: BriefingOutput): string {
+  const parts: string[] = [briefing.greeting];
+  if (briefing.lede) parts.push(briefing.lede);
+
+  for (const { category, label } of CATEGORY_ORDER) {
+    const items = briefing.sections.filter((s) => s.category === category);
+    if (items.length === 0) continue;
+    const lines = [`## ${label}`, ...items.map((s) => `- ${s.text}`)];
+    parts.push(lines.join("\n"));
+  }
+
+  return parts.join("\n\n");
+}

src/tools/core-source.ts

@@ -23,6 +23,7 @@ import { ActivityCollector } from "../services/activity-collector.ts";
 import { BriefingCache } from "../services/briefing-cache.ts";
 import { collectBriefingFacets } from "../services/briefing-collector.ts";
 import { BriefingGenerator } from "../services/briefing-generator.ts";
+import { renderBriefingText } from "../services/briefing-render.ts";
 import type { BriefingOutput } from "../services/home-types.ts";
 
 /**
@@ -757,8 +758,12 @@ export function createCoreToolDefs(runtime: Runtime): InProcessTool[] {
             }
             const briefingCache = cache;
 
+            // `content` carries the rendered briefing (the only field the model
+            // sees — the engine never feeds `structuredContent` to the prompt),
+            // prefixed with the status note. `structuredContent` keeps the typed
+            // payload for the dashboard, unchanged.
             const ok = (briefing: BriefingOutput, note: string): ToolResult => ({
-              content: textContent(note),
+              content: textContent(`${note}\n\n${renderBriefingText(briefing)}`),
               structuredContent: briefing as unknown as Record<string, unknown>,
               isError: false,
             });

test/unit/services/briefing-render.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, test } from "bun:test";
+import { renderBriefingText } from "../../../src/services/briefing-render.ts";
+import type { BriefingOutput, BriefingSection } from "../../../src/services/home-types.ts";
+
+function section(overrides: Partial<BriefingSection> & Pick<BriefingSection, "category">): BriefingSection {
+	return {
+		id: "s1",
+		text: "Something happened",
+		type: "neutral",
+		...overrides,
+	};
+}
+
+function makeBriefing(overrides?: Partial<BriefingOutput>): BriefingOutput {
+	return {
+		greeting: "Good morning, Mat",
+		date: "Tuesday, June 2, 2026",
+		lede: "Two things need your attention.",
+		sections: [],
+		state: "normal",
+		generated_at: "2026-06-02T16:00:00.000Z",
+		cached: false,
+		...overrides,
+	};
+}
+
+describe("renderBriefingText", () => {
+	// The core regression: the briefing body must land in the rendered text, not
+	// only in structuredContent. The model only ever sees this string.
+	test("renders the section body text the model needs", () => {
+		const out = renderBriefingText(
+			makeBriefing({
+				sections: [
+					section({ category: "attention", type: "warning", text: "Invoice #42 is overdue" }),
+					section({ category: "recent", type: "positive", text: "Deploy succeeded" }),
+				],
+			}),
+		);
+		expect(out).toContain("Invoice #42 is overdue");
+		expect(out).toContain("Deploy succeeded");
+	});
+
+	test("includes greeting and lede", () => {
+		const out = renderBriefingText(makeBriefing());
+		expect(out).toContain("Good morning, Mat");
+		expect(out).toContain("Two things need your attention.");
+	});
+
+	// Guards the schema category names (home.ts: attention/recent/upcoming).
+	// A renderer keyed on the inline script's stale names (needs_attention/
+	// coming_up) would silently drop every section — the failure mode this fix
+	// exists to prevent.
+	test("groups sections under labels using the schema category names", () => {
+		const out = renderBriefingText(
+			makeBriefing({
+				sections: [
+					section({ category: "upcoming", text: "Renewal due Friday" }),
+					section({ category: "attention", text: "API key expiring" }),
+					section({ category: "recent", text: "3 new conversations" }),
+				],
+			}),
+		);
+		expect(out).toContain("## Needs attention");
+		expect(out).toContain("## Recent");
+		expect(out).toContain("## Coming up");
+		// attention surfaces before recent, which surfaces before upcoming
+		expect(out.indexOf("## Needs attention")).toBeLessThan(out.indexOf("## Recent"));
+		expect(out.indexOf("## Recent")).toBeLessThan(out.indexOf("## Coming up"));
+	});
+
+	test("omits headings for empty categories", () => {
+		const out = renderBriefingText(
+			makeBriefing({ sections: [section({ category: "recent", text: "Only recent activity" })] }),
+		);
+		expect(out).toContain("## Recent");
+		expect(out).not.toContain("## Needs attention");
+		expect(out).not.toContain("## Coming up");
+	});
+
+	test("renders a quiet briefing as greeting + lede with no headings", () => {
+		const out = renderBriefingText(makeBriefing({ sections: [], lede: "All clear." }));
+		expect(out).toContain("Good morning, Mat");
+		expect(out).toContain("All clear.");
+		expect(out).not.toContain("##");
+	});
+});