Stop saving prefix-only mode when inline suggestions turn on

src/ui/options/settings.ts

@@ -154,17 +154,29 @@ function wireImportExportHandlers(registry: SettingsRegistry): void {
   });
 }
 
+// The stored prefix-only value of each control while inline mode shows it as on.
+const prefixOnlyBeforeInline = new WeakMap<object, unknown>();
+
 function applyInlineSuggestionLocks(registry: SettingsRegistry, enabled: boolean): void {
+  const prefixOnly = registry[KEY_PREFIX_ONLY_MODE];
   if (enabled) {
     const locks: Array<[string, unknown]> = [
       [KEY_AUTOCOMPLETE_ON_TAB, true],
       [KEY_NUM_SUGGESTIONS, 10],
-      [KEY_PREFIX_ONLY_MODE, true],
     ];
     for (const [key, value] of locks) {
       // A select control gives its value as a string.
       if (String(registry[key].get()) !== String(value)) registry[key].set(value);
     }
+    // ConfigAssembler forces prefix-only mode while inline mode is on. Thus show it without a write,
+    // so that the user's value comes back when inline mode goes off.
+    if (prefixOnly.get() !== true) {
+      prefixOnlyBeforeInline.set(prefixOnly, prefixOnly.get());
+      prefixOnly.set(true, true);
+    }
+  } else if (prefixOnlyBeforeInline.has(prefixOnly)) {
+    prefixOnly.set(prefixOnlyBeforeInline.get(prefixOnly), true);
+    prefixOnlyBeforeInline.delete(prefixOnly);
   }
   registry[KEY_AUTOCOMPLETE_ON_TAB].setDisabled(enabled);
   registry[KEY_PREFIX_ONLY_MODE].setDisabled(enabled);

tests/e2e/e2e-helpers.ts

@@ -129,7 +129,7 @@ function cacheChromeExtensionHost(candidate: string | null | undefined): void {
 
 function isRetriableBackgroundContextError(error: unknown): boolean {
   const message = error instanceof Error ? error.message : String(error);
-  return /Execution context was destroyed|Execution context is not available in detached frame or worker|Cannot find context with specified id|Session closed|Target closed|Connection closed|background worker is unavailable|Waiting failed|NoSuchFrameError|Browsing Context with id .* not found/i.test(
+  return /Execution context was destroyed|Execution context is not available in detached frame or worker|Cannot find context with specified id|Session closed|Target closed|Connection closed|background worker is unavailable|Waiting failed|Timed out after waiting \d+ms|NoSuchFrameError|Browsing Context with id .* not found/i.test(
     message,
   );
 }

tests/options.page.test.ts

@@ -197,6 +197,26 @@ describe("options page settings handlers", () => {
       expect(writes).toEqual([...expected]);
     },
   );
+
+  test("inline mode shows prefix-only mode as on but keeps the stored value", () => {
+    stubConfigChangeSender();
+    const registry = fakeRegistry({
+      [KEY_INLINE_SUGGESTION]: false,
+      [KEY_AUTOCOMPLETE_ON_TAB]: true,
+      [KEY_NUM_SUGGESTIONS]: "10",
+      [KEY_PREFIX_ONLY_MODE]: false,
+    });
+    wireRuntimeSettingsHandlers(registry);
+    const prefixOnly = registry[KEY_PREFIX_ONLY_MODE];
+
+    registry[KEY_INLINE_SUGGESTION].set(true);
+    expect(prefixOnly.get()).toBe(true);
+
+    registry[KEY_INLINE_SUGGESTION].set(false);
+    expect(prefixOnly.get()).toBe(false);
+    // ConfigAssembler forces prefix-only mode while inline mode is on, so no write is needed.
+    expect(prefixOnly.calls.every((call) => call.silent)).toBe(true);
+  });
 });
 
 async function flushPage(rounds = 30): Promise<void> {