refactor(layout): promote AI capture above timeline on desktop

Give the composer full-width desktop space before the event timeline so capture stays prominent and the toolbar can keep its intended two-column composition. Add source-level regression tests to lock the new page hierarchy in place.

src/app/page.tsx

@@ -436,10 +436,8 @@ export default function HomePage() {
 	);
 	const appSectionSurfaceClasses = getAppSectionSurfaceClasses(isMobile);
 	const appNavSurfaceClasses = getAppNavSurfaceClasses(isMobile);
-	const mainContentClasses = cn(
-		"grid items-start gap-4",
-		isMobile ? "grid-cols-1" : "grid-cols-[minmax(0,0.75fr)_minmax(0,1.25fr)]",
-	);
+	const mainContentClasses = "space-y-4";
+	const timelineContentClasses = "space-y-4";
 	const headerActionsClasses = isMobile
 		? "flex w-full items-center justify-between gap-2"
 		: "flex flex-wrap items-center justify-end gap-2";
@@ -552,7 +550,6 @@ export default function HomePage() {
 						/>
 					) : (
 						<section className={mainContentClasses}>
-							<div className="space-y-4">
 							<section className={appSectionSurfaceClasses}>
 								<div className="mb-4 space-y-1">
 									<p className="text-xs font-medium uppercase tracking-[0.18em] text-muted-foreground">
@@ -562,8 +559,8 @@ export default function HomePage() {
 										Capture from text or files.
 									</h2>
 									<p className="text-sm leading-6 text-muted-foreground">
-											Start with a prompt, screenshots, or both. Review happens
-											in the timeline rather than a separate flow.
+										Start with a prompt, screenshots, or both. Review happens in
+										the timeline rather than a separate flow.
 									</p>
 								</div>
 
@@ -587,9 +584,8 @@ export default function HomePage() {
 									events={events}
 								/>
 							</section>
-							</div>
 
-							<div className="space-y-4">
+							<section className={timelineContentClasses}>
 								<section className={appSectionSurfaceClasses}>
 									<div className="mb-4 flex items-center justify-between gap-3">
 										<div className="space-y-1">
@@ -634,7 +630,7 @@ export default function HomePage() {
 										onDelete={handleDelete}
 									/>
 								</section>
-							</div>
+							</section>
 						</section>
 					)}
 				</main>

tests/ai-toolbar.test.ts

@@ -166,6 +166,14 @@ describe("AI capture redesign", () => {
 		expect(source).not.toContain("lg:grid-cols-");
 	});
 
+	test("desktop composer uses a two-column row when the page gives it full-width space", () => {
+		const source = readToolbarSource();
+
+		expect(source).toContain("isMobile");
+		expect(source).toContain('? "grid gap-3"');
+		expect(source).toContain(': "grid gap-3 grid-cols-[minmax(0,1fr)_minmax(0,1fr)]"');
+	});
+
 	test("attachments panel is a first-class surfaced region, not an inline footer affordance", () => {
 		const source = readToolbarSource();
 

tests/home-page-layout.test.ts

@@ -6,13 +6,22 @@ describe("home page hierarchy", () => {
 		const source = readFileSync("src/app/page.tsx", "utf8");
 
 		expect(source).toContain("useIsMobile");
-		expect(source).toContain("grid-cols-[minmax(0,0.75fr)_minmax(0,1.25fr)]");
+		expect(source).toContain('const mainContentClasses = "space-y-4"');
+		expect(source).toContain('const timelineContentClasses = "space-y-4"');
 		expect(source).toContain('"items-center justify-between"');
 		expect(source).toContain("desktopUtilityActionsClasses");
 		expect(source).toContain("AI capture");
 		expect(source).toContain("Event timeline");
 	});
 
+	test("desktop layout promotes AI capture to a full-width top row before the timeline grid", () => {
+		const source = readFileSync("src/app/page.tsx", "utf8");
+
+		expect(source).toContain("<section className={appSectionSurfaceClasses}>");
+		expect(source).toContain("<section className={timelineContentClasses}>");
+		expect(source).not.toContain("grid-cols-[minmax(0,0.75fr)_minmax(0,1.25fr)]");
+	});
+
 	test("manual create is routed through a More menu instead of a primary mobile action", () => {
 		const source = readFileSync("src/app/page.tsx", "utf8");