Fix wave: dropdown keyboard/focus, appearance resets, inline key editors, content-sized slider

- MenuShell: after placement, focus lands in the search when the menu has
  one, else the body (tabIndex -1) — the lists' mount-time focus ran during
  the hidden measuring pass and silently failed, so no dropdown ever opened
  focused. The body owns the arrow machine for searchless menus:
  ArrowDown/Up cycle options with wrap (first/last entry from the body,
  native-select convention), Home/End, Enter activates, preventDefault so
  arrows never scroll the page.
- Appearance: the CSS-var applier only ever setProperty'd — a later write
  omitting a var left the stale inline value forever (empty background
  never reset, serif toggle-back looked dead). appliedNamesRef tracks what
  was set; staleVarNames (pure, exported) returns what to removeProperty.
- CommitInput: controlled — after a commit the field snaps to the stored
  record, so the clamp on a -5 prose size is visible (12), Esc reverts.
- Keys: Add-provider dropdown closes on pick; the paste row is inline
  (label | input | Save | Cancel); existing-row editors go inline with an
  explicit Cancel beside Save/Delete — folding is visible, not Esc-only.
- Graph context: readout is content-sized (tabular-nums) — no fixed-width
  dead gap when "off"; the dictation strip fills whatever space remains.

Gates: tsc clean, 866/866 tests (new staleVarNames suite), lint 0, build ok.
Live-verified via Playwright: dropdown focus+arrow cycles+wrap+Enter pick,
background set→empty reset, serif round-trip, visible clamp to 12, provider
pick closes menu, inline editor + Cancel + Esc fold, slider width 270→277px.

tests/settings-pure.test.ts

@@ -7,7 +7,7 @@
 
 import assert from "node:assert/strict";
 import { describe, it } from "node:test";
-import { appearanceVars, derivedPalette, resolveAppearance } from "../components/settings/appearance.tsx";
+import { appearanceVars, derivedPalette, resolveAppearance, staleVarNames } from "../components/settings/appearance.tsx";
 import {
 	composePromptSwitch,
 	composeSearchEngine,
@@ -105,6 +105,42 @@ describe("appearanceVars — the mapping the provider applies", () => {
 	});
 });
 
+describe("staleVarNames — the removal half of application (owner repro: resets never reverted)", () => {
+	it("a full delta applied, then factory: every delta-only name goes stale", () => {
+		const fullDelta = appearanceVars(
+			resolveAppearance({
+				background: "#101820",
+				fontFamily: "Georgia",
+				sessionNameSerif: false,
+				mdRendering: { headingWeight: 700, boldColor: "#ff0000", italicColor: "#00ff00" },
+			}),
+		);
+		const applied = Object.keys(fullDelta);
+		const factory = appearanceVars(resolveAppearance(undefined));
+		const stale = staleVarNames(applied, factory);
+		assert.ok(stale.includes("--background"));
+		assert.ok(stale.includes("--font-prose"));
+		assert.ok(stale.includes("--font-title"), "serif toggle back ON must clear the title override");
+		assert.ok(stale.includes("--lh-ink-strong"));
+		assert.ok(stale.includes("--lh-ink-italic"));
+		assert.ok(!stale.includes("--lh-prose-size"), "always-applied tokens never go stale");
+		assert.ok(!stale.includes("--lh-heading-weight"), "always-applied tokens never go stale");
+	});
+
+	it("an empty background commit (null = factory) frees the palette vars", () => {
+		const withBg = appearanceVars(resolveAppearance({ background: "#101010" }));
+		const emptied = appearanceVars(resolveAppearance({ background: null }));
+		const stale = staleVarNames(Object.keys(withBg), emptied);
+		assert.ok(stale.includes("--background"));
+		assert.ok(stale.includes("--card"), "the derived palette follows the background out");
+		assert.equal(emptied["--background"], undefined);
+	});
+
+	it("no previous applications → nothing stale", () => {
+		assert.deepEqual(staleVarNames([], appearanceVars(resolveAppearance(undefined))), []);
+	});
+});
+
 describe("agent section compose helpers — the replace-whole PUT body", () => {
 	it("composeTool carries the rest of the section verbatim", () => {
 		const before = { tools: { demo: false }, prompts: { "system-prompt.md": true } };