diff --git a/docs/subagents/INDEX.md b/docs/subagents/INDEX.md
index 8404fcb..3e3eaf2 100644
--- a/docs/subagents/INDEX.md
+++ b/docs/subagents/INDEX.md
@@ -6,7 +6,7 @@ Read first. Keep concise.
 | ------------ | -------------- | ---------------------------------------------------- | --------- | ------------------------------------- | ---------------------- |
 | `codex-generate-minecard-image-20260220T112900Z-vsxr` | `codex-generate-minecard-image` | `Generate media fallbacks (GIF) from assets/minecard.webm and wire README/docs fallback markup` | `done` | `docs/subagents/agents/codex-generate-minecard-image-20260220T112900Z-vsxr.md` | `2026-02-20T11:35:30Z` |
 | `codex-main` | `planner-exec` | `Fix frequency/N+1 regression in plugin --start flow` | `in_progress` | `docs/subagents/agents/codex-main.md` | `2026-02-19T19:36:46Z` |
-| `codex-task85-20260219T233711Z-46hc` | `codex-task85` | `Resume TASK-85 maintainability refactor from latest handoff point` | `in_progress` | `docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md` | `2026-02-20T10:15:51Z` |
+| `codex-task85-20260219T233711Z-46hc` | `codex-task85` | `Resume TASK-85 maintainability refactor from latest handoff point` | `in_progress` | `docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md` | `2026-02-20T10:17:29Z` |
 | `codex-config-validation-20260219T172015Z-iiyf` | `codex-config-validation` | `Find root cause of config validation error for ~/.config/SubMiner/config.jsonc` | `completed` | `docs/subagents/agents/codex-config-validation-20260219T172015Z-iiyf.md` | `2026-02-19T17:26:17Z` |
 | `codex-task85-20260219T233711Z-46hc` | `codex-task85` | `Resume TASK-85 maintainability refactor from latest handoff point` | `in_progress` | `docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md` | `2026-02-20T02:56:34Z` |
 | `codex-anilist-deeplink-20260219T233926Z` | `anilist-deeplink` | `Fix external subminer:// AniList callback handling from browser` | `done` | `docs/subagents/agents/codex-anilist-deeplink-20260219T233926Z.md` | `2026-02-19T23:59:21Z` |
diff --git a/docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md b/docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md
index 07f0a9e..582498f 100644
--- a/docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md
+++ b/docs/subagents/agents/codex-task85-20260219T233711Z-46hc.md
@@ -9,6 +9,10 @@
 
 ## Current Work (newest first)
 
+- [2026-02-20T10:17:29Z] progress: extracted Yomitan settings opener composition from `src/main.ts` into `src/main/runtime/yomitan-settings-runtime.ts`; `main.ts` now uses `createYomitanSettingsRuntime(...)` and consumes `openYomitanSettings` from that runtime.
+- [2026-02-20T10:17:29Z] progress: added `src/main/runtime/yomitan-settings-runtime.test.ts` for composed runtime behavior.
+- [2026-02-20T10:17:29Z] test: `bun run build` pass (expected macOS helper Swift cache fallback) + focused suites pass for `yomitan-settings-runtime*`, `yomitan-settings-opener*`, `yomitan-extension-runtime*`, `cli-command-context-factory*`, and `tray-runtime-handlers*` (7/7).
+- [2026-02-20T10:17:29Z] scope: staging `src/main.ts`, new yomitan settings runtime module/tests, and subagent bookkeeping only.
 - [2026-02-20T10:15:51Z] progress: extracted overlay window factory composition from `src/main.ts` into `src/main/runtime/overlay-window-runtime-handlers.ts`; `main.ts` now composes overlay/main/invisible window handlers via one runtime factory.
 - [2026-02-20T10:15:51Z] progress: added `src/main/runtime/overlay-window-runtime-handlers.test.ts` for composed window handler wiring.
 - [2026-02-20T10:15:51Z] test: `bun run build` pass (expected macOS helper Swift cache fallback) + focused suites pass for `overlay-window-runtime-handlers*`, `overlay-window-factory*`, `overlay-runtime-bootstrap*`, `tray-runtime-handlers*`, and `cli-command-context-factory*` (9/9).
diff --git a/src/main.ts b/src/main.ts
index 432dec2..41ba599 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -290,7 +290,6 @@ import {
 } from './main/runtime/overlay-window-layout-main-deps';
 import { buildTrayMenuTemplateRuntime, resolveTrayIconPathRuntime } from './main/runtime/tray-runtime';
 import { createInitializeOverlayRuntimeHandler } from './main/runtime/overlay-runtime-bootstrap';
-import { createOpenYomitanSettingsHandler } from './main/runtime/yomitan-settings-opener';
 import {
   createGetConfiguredShortcutsHandler,
   createRefreshGlobalAndOverlayShortcutsHandler,
@@ -384,10 +383,10 @@ import { createBuildMpvCommandFromIpcRuntimeMainDepsHandler } from './main/runti
 import { createOverlayWindowRuntimeHandlers } from './main/runtime/overlay-window-runtime-handlers';
 import {
   createBuildInitializeOverlayRuntimeBootstrapMainDepsHandler,
-  createBuildOpenYomitanSettingsMainDepsHandler,
 } from './main/runtime/app-runtime-main-deps';
 import { createTrayRuntimeHandlers } from './main/runtime/tray-runtime-handlers';
 import { createYomitanExtensionRuntime } from './main/runtime/yomitan-extension-runtime';
+import { createYomitanSettingsRuntime } from './main/runtime/yomitan-settings-runtime';
 import { createBuildInitializeOverlayRuntimeOptionsHandler } from './main/runtime/overlay-runtime-options';
 import { createBuildInitializeOverlayRuntimeMainDepsHandler } from './main/runtime/overlay-runtime-options-main-deps';
 import {
@@ -3126,24 +3125,22 @@ const initializeOverlayRuntimeHandler = createInitializeOverlayRuntimeHandler(
     startBackgroundWarmups: () => startBackgroundWarmups(),
   })(),
 );
-const openYomitanSettingsHandler = createOpenYomitanSettingsHandler(
-  createBuildOpenYomitanSettingsMainDepsHandler({
-    ensureYomitanExtensionLoaded: () => ensureYomitanExtensionLoaded(),
-    openYomitanSettingsWindow: ({ yomitanExt, getExistingWindow, setWindow }) => {
-      openYomitanSettingsWindow({
-        yomitanExt: yomitanExt as Extension,
-        getExistingWindow: () => getExistingWindow() as BrowserWindow | null,
-        setWindow: (window) => setWindow(window as BrowserWindow | null),
-      });
-    },
-    getExistingWindow: () => appState.yomitanSettingsWindow,
-    setWindow: (window) => {
-      appState.yomitanSettingsWindow = window as BrowserWindow | null;
-    },
-    logWarn: (message) => logger.warn(message),
-    logError: (message, error) => logger.error(message, error),
-  })(),
-);
+const { openYomitanSettings: openYomitanSettingsHandler } = createYomitanSettingsRuntime({
+  ensureYomitanExtensionLoaded: () => ensureYomitanExtensionLoaded(),
+  openYomitanSettingsWindow: ({ yomitanExt, getExistingWindow, setWindow }) => {
+    openYomitanSettingsWindow({
+      yomitanExt: yomitanExt as Extension,
+      getExistingWindow: () => getExistingWindow() as BrowserWindow | null,
+      setWindow: (window) => setWindow(window as BrowserWindow | null),
+    });
+  },
+  getExistingWindow: () => appState.yomitanSettingsWindow,
+  setWindow: (window) => {
+    appState.yomitanSettingsWindow = window as BrowserWindow | null;
+  },
+  logWarn: (message) => logger.warn(message),
+  logError: (message, error) => logger.error(message, error),
+});
 
 async function updateLastCardFromClipboard(): Promise<void> {
   await updateLastCardFromClipboardHandler();
diff --git a/src/main/runtime/yomitan-settings-runtime.test.ts b/src/main/runtime/yomitan-settings-runtime.test.ts
new file mode 100644
index 0000000..f5b843b
--- /dev/null
+++ b/src/main/runtime/yomitan-settings-runtime.test.ts
@@ -0,0 +1,31 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { createYomitanSettingsRuntime } from './yomitan-settings-runtime';
+
+test('yomitan settings runtime composes opener with built deps', async () => {
+  let existingWindow: { id: string } | null = null;
+  const calls: string[] = [];
+
+  const runtime = createYomitanSettingsRuntime({
+    ensureYomitanExtensionLoaded: async () => ({ id: 'ext' }),
+    openYomitanSettingsWindow: ({ getExistingWindow, setWindow }) => {
+      calls.push('open-window');
+      const current = getExistingWindow();
+      if (!current) {
+        setWindow({ id: 'settings' });
+      }
+    },
+    getExistingWindow: () => existingWindow as never,
+    setWindow: (window) => {
+      existingWindow = window as { id: string } | null;
+    },
+    logWarn: (message) => calls.push(`warn:${message}`),
+    logError: (message) => calls.push(`error:${message}`),
+  });
+
+  runtime.openYomitanSettings();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  assert.deepEqual(existingWindow, { id: 'settings' });
+  assert.deepEqual(calls, ['open-window']);
+});
diff --git a/src/main/runtime/yomitan-settings-runtime.ts b/src/main/runtime/yomitan-settings-runtime.ts
new file mode 100644
index 0000000..4671678
--- /dev/null
+++ b/src/main/runtime/yomitan-settings-runtime.ts
@@ -0,0 +1,13 @@
+import { createBuildOpenYomitanSettingsMainDepsHandler } from './app-runtime-main-deps';
+import { createOpenYomitanSettingsHandler } from './yomitan-settings-opener';
+
+type OpenYomitanSettingsMainDeps = Parameters<typeof createBuildOpenYomitanSettingsMainDepsHandler>[0];
+
+export function createYomitanSettingsRuntime(deps: OpenYomitanSettingsMainDeps) {
+  const openYomitanSettingsMainDeps = createBuildOpenYomitanSettingsMainDepsHandler(deps)();
+  const openYomitanSettings = createOpenYomitanSettingsHandler(openYomitanSettingsMainDeps);
+
+  return {
+    openYomitanSettings,
+  };
+}