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.

components/sidebar.tsx

@@ -3,7 +3,7 @@
 import { createContext, useCallback, useContext, useEffect, useMemo, useRef, useState } from "react";
 import Link from "next/link";
 import { usePathname, useRouter } from "next/navigation";
-import { PanelLeftCloseIcon, PanelLeftOpenIcon, PlusIcon, SearchIcon } from "lucide-react";
+import { PanelLeftCloseIcon, PanelLeftOpenIcon, PlusIcon, SearchIcon, SettingsIcon } from "lucide-react";
 import { ActivitySection } from "@/components/activity-dock";
 import { LhMark } from "@/components/lh-mark";
 import { BrailleSpinner } from "@/components/braille-spinner";
@@ -482,6 +482,20 @@ function SessionsSidebar() {
 					    flex-1, so this pins to the bottom. Sidebar closed = the
 					    learner opted out (no ambient signal, user decision). */}
 					<ActivitySection />
+
+					{/* Settings entry (thin settings wave): the same row language
+					    as New session — quiet, bottom-pinned, one chord away is
+					    mod+, (the keyboard registry's open-settings action). */}
+					<div className="px-3 pb-3 pt-1">
+						<Link
+							href="/settings"
+							data-testid="settings-entry"
+							className="flex items-center gap-1.5 rounded-md px-2 py-1.5 text-xs uppercase tracking-wider text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+						>
+							<SettingsIcon className="size-3" />
+							Settings
+						</Link>
+					</div>
 				</div>
 			</aside>
 	);