Thin working settings UI (owner-approved plan): /settings + live appearance + keyboard rebinding

The validation surface for the settings foundation — deliberately thin,
real read/write against the delta record, polish is a later wave.

Mount (owner decisions): dedicated page, single scroll; entry = sidebar
bottom row + ⌘/Ctrl+, (open-settings in the registry); chat defaults NOT
shown (they live on /chat/new); mode dark-only (light palette = design
wave); final tool list = research/demo/visual/pdf (master-adjudicated).

Sections (PUT /api/settings/[section], replace-whole per section):
- General: auto-update toggle.
- Agent: six background-role model+thinking selects (Default = config
  pin; a stored id stays VISIBLE even when the catalog hasn't loaded or
  dropped it — a select showing Default over a live override would lie),
  the four tool toggles, prompt override switches (file-gated) with
  source/override text editors over the segment routes.
- Appearance: applied LIVE as runtime CSS variables by an
  AppearanceProvider at the root layout — proseFontSize → the one
  reading-size var, fontFamily → --font-prose, background → --background
  + the derived raised/accent/edge palette (dark curve, today's exact
  spacing: +8/+22/+47 per channel, clamped), sessionNameSerif →
  --font-title (titles flip with ZERO chat.tsx edits), headingWeight →
  new --lh-heading-weight token, bold/italic colors → the lh-ink vars.
  Mode renders honestly DISABLED.
- Graph: the ladder grays a rung when any ANCESTOR is effectively off
  (stored values persist, resolve inert — switch shows stored, graying
  shows effective).
- Keyboard: view/rebind/reset over the registry; overrides persist in
  lh:keymap and apply INSTANTLY (dispatcher reads per keydown); bare
  modifier presses are ignored while armed; displayOnly actions list but
  never rebind.

First-boot fix: {settings: null} is no-record, not fetch-failure.

CROSS-LANE (flagged for master): src/core/keyboard.ts gained the
open-settings action/binding and exports saveOverrides/loadOverrides
(one-liners; no existing pins); app/layout.tsx mounts the provider.

Live-verified: structure, record writes (general/tools/graph/appearance),
prose-size applying live (16→20px), rebind + chord navigation from
another page, ladder graying, no console errors. Gates: typecheck,
lint, 689/689 (28 new), build.

app/globals.css

@@ -48,6 +48,8 @@
 	   the reskin's hand-tuned 16.5 to the ladder's 16.) */
 	--lh-prose-size: 16px;
 	--lh-prose-leading: 1.5;
+	/* Markdown heading weight (appearance settings; 900 = the Black cut). */
+	--lh-heading-weight: 900;
 }
 
 /* The app is always dark (<html class="dark">); mirror the same values so
@@ -80,6 +82,8 @@
 	   the reskin's hand-tuned 16.5 to the ladder's 16.) */
 	--lh-prose-size: 16px;
 	--lh-prose-leading: 1.5;
+	/* Markdown heading weight (appearance settings; 900 = the Black cut). */
+	--lh-heading-weight: 900;
 }
 
 /* CMU Serif bold (titles) — bundled local file, no CDN dependency. */
@@ -185,7 +189,7 @@ body {
    :where keeps specificity zero. Chrome titles (CMU Serif) don't live
    under .lh-prose and stay untouched. */
 .lh-prose :where(h1, h2, h3, h4, h5, h6) {
-	font-weight: 900;
+	font-weight: var(--lh-heading-weight, 900);
 }
 
 /* lh-input (owner, typography round 2): lh-prose's 1.5 READING leading

app/layout.tsx

@@ -4,6 +4,7 @@ import "katex/dist/katex.min.css";
 import "./globals.css";
 import { AppShell, SidebarProvider } from "@/components/sidebar";
 import { ActivityProvider } from "@/components/activity-dock";
+import { AppearanceProvider } from "@/components/settings/appearance";
 
 // Chrome = JetBrains Mono, teaching prose = Source Sans 3, titles = CMU
 // Serif (the bundled lh-cmu @font-face in globals.css — no CDN).
@@ -19,11 +20,13 @@ export default function RootLayout({ children }: { children: React.ReactNode })
 	return (
 		<html lang="en" className={`dark ${ui.variable} ${prose.variable}`}>
 			<body className="min-h-dvh antialiased">
-			<SidebarProvider>
-				<ActivityProvider>
-					<AppShell>{children}</AppShell>
-				</ActivityProvider>
-			</SidebarProvider>
+			<AppearanceProvider>
+				<SidebarProvider>
+					<ActivityProvider>
+						<AppShell>{children}</AppShell>
+					</ActivityProvider>
+				</SidebarProvider>
+			</AppearanceProvider>
 		</body>
 		</html>
 	);

app/settings/page.tsx

@@ -0,0 +1,8 @@
+/** The settings route (thin settings wave): server shell over the client
+ *  page — same shape as the chat routes (AppShell wraps via the root
+ *  layout, so the sidebar + its Settings entry come along). */
+import { SettingsPage } from "@/components/settings/settings-page.tsx";
+
+export default function Page() {
+	return <SettingsPage />;
+}