Refactor AppHost into its own module

benchmarks/highlight-prefetch.ts

@@ -5,7 +5,7 @@ import React from "react";
 import { testRender } from "@opentui/react/test-utils";
 import { parseDiffFromFile } from "@pierre/diffs";
 import { act } from "react";
-import { AppHost } from "../src/ui/App";
+import { AppHost } from "../src/ui/AppHost";
 import type { AppBootstrap, DiffFile } from "../src/core/types";
 
 function createDiffFile(index: number, marker: string): DiffFile {

benchmarks/large-stream.ts

@@ -4,7 +4,7 @@ import { performance } from "perf_hooks";
 import React from "react";
 import { testRender } from "@opentui/react/test-utils";
 import { act } from "react";
-import { AppHost } from "../src/ui/App";
+import { AppHost } from "../src/ui/AppHost";
 import {
   createLargeSplitStreamBootstrap,
   DEFAULT_FILE_COUNT,

src/main.tsx

@@ -7,7 +7,7 @@ import { pagePlainText } from "./core/pager";
 import { shutdownSession } from "./core/shutdown";
 import { prepareStartupPlan } from "./core/startup";
 import { resolveStartupUpdateNotice } from "./core/updateNotice";
-import { AppHost } from "./ui/App";
+import { AppHost } from "./ui/AppHost";
 import { HunkHostClient } from "./mcp/client";
 import { serveHunkMcpServer } from "./mcp/server";
 import { createInitialSessionSnapshot, createSessionRegistration } from "./mcp/sessionRegistration";

src/ui/App.tsx

@@ -16,17 +16,9 @@ import {
   useState,
   useRef,
 } from "react";
-import { resolveConfiguredCliInput } from "../core/config";
-import { loadAppBootstrap } from "../core/loaders";
-import { resolveRuntimeCliInput } from "../core/terminal";
 import type { AppBootstrap, CliInput, LayoutMode } from "../core/types";
 import { canReloadInput, computeWatchSignature } from "../core/watch";
-import type { UpdateNotice } from "../core/updateNotice";
 import { HunkHostClient } from "../mcp/client";
-import {
-  createInitialSessionSnapshot,
-  updateSessionRegistration,
-} from "../mcp/sessionRegistration";
 import type { ReloadedSessionResult } from "../mcp/types";
 import { MenuBar } from "./components/chrome/MenuBar";
 import { StatusBar } from "./components/chrome/StatusBar";
@@ -35,7 +27,6 @@ import { FilesPane } from "./components/panes/FilesPane";
 import { PaneDivider } from "./components/panes/PaneDivider";
 import { useHunkSessionBridge } from "./hooks/useHunkSessionBridge";
 import { useMenuController } from "./hooks/useMenuController";
-import { useStartupUpdateNotice } from "./hooks/useStartupUpdateNotice";
 import { buildAppMenus } from "./lib/appMenus";
 import { buildSidebarEntries, filterReviewFiles, mergeFileAnnotationsByFileId } from "./lib/files";
 import { buildAnnotatedHunkCursors, buildHunkCursors, findNextHunkCursor } from "./lib/hunks";
@@ -85,7 +76,7 @@ function withCurrentViewOptions(
 }
 
 /** Orchestrate global app state, layout, navigation, and pane coordination. */
-function App({
+export function App({
   bootstrap,
   hostClient,
   noticeText,
@@ -1044,73 +1035,3 @@ function App({
     </box>
   );
 }
-
-/** Keep one live Hunk app mounted while allowing daemon-driven session reloads. */
-export function AppHost({
-  bootstrap,
-  hostClient,
-  onQuit = () => process.exit(0),
-  startupNoticeResolver,
-}: {
-  bootstrap: AppBootstrap;
-  hostClient?: HunkHostClient;
-  onQuit?: () => void;
-  startupNoticeResolver?: () => Promise<UpdateNotice | null>;
-}) {
-  const [activeBootstrap, setActiveBootstrap] = useState(bootstrap);
-  const [appVersion, setAppVersion] = useState(0);
-  const startupNoticeText = useStartupUpdateNotice({
-    enabled: !bootstrap.input.options.pager,
-    resolver: startupNoticeResolver,
-  });
-
-  const reloadSession = useCallback(
-    async (nextInput: CliInput, options?: { resetApp?: boolean; sourcePath?: string }) => {
-      const runtimeInput = resolveRuntimeCliInput(nextInput);
-      const configuredInput = resolveConfiguredCliInput(runtimeInput, {
-        cwd: options?.sourcePath,
-      }).input;
-      const nextBootstrap = await loadAppBootstrap(configuredInput, {
-        cwd: options?.sourcePath,
-      });
-      const nextSnapshot = createInitialSessionSnapshot(nextBootstrap);
-
-      let sessionId = "local-session";
-      if (hostClient) {
-        const nextRegistration = updateSessionRegistration(
-          hostClient.getRegistration(),
-          nextBootstrap,
-        );
-        sessionId = nextRegistration.sessionId;
-        hostClient.replaceSession(nextRegistration, nextSnapshot);
-      }
-
-      setActiveBootstrap(nextBootstrap);
-      if (options?.resetApp !== false) {
-        setAppVersion((current) => current + 1);
-      }
-
-      return {
-        sessionId,
-        inputKind: nextBootstrap.input.kind,
-        title: nextBootstrap.changeset.title,
-        sourceLabel: nextBootstrap.changeset.sourceLabel,
-        fileCount: nextBootstrap.changeset.files.length,
-        selectedFilePath: nextSnapshot.selectedFilePath,
-        selectedHunkIndex: nextSnapshot.selectedHunkIndex,
-      };
-    },
-    [hostClient],
-  );
-
-  return (
-    <App
-      key={appVersion}
-      bootstrap={activeBootstrap}
-      hostClient={hostClient}
-      noticeText={startupNoticeText}
-      onQuit={onQuit}
-      onReloadSession={reloadSession}
-    />
-  );
-}

src/ui/AppHost.tsx

@@ -0,0 +1,92 @@
+import { useCallback, useState } from "react";
+import { resolveConfiguredCliInput } from "../core/config";
+import { loadAppBootstrap } from "../core/loaders";
+import { resolveRuntimeCliInput } from "../core/terminal";
+import type { AppBootstrap, CliInput } from "../core/types";
+import type { UpdateNotice } from "../core/updateNotice";
+import { HunkHostClient } from "../mcp/client";
+import {
+  createInitialSessionSnapshot,
+  updateSessionRegistration,
+} from "../mcp/sessionRegistration";
+import { App } from "./App";
+import { useStartupUpdateNotice } from "./hooks/useStartupUpdateNotice";
+
+/** Keep one live Hunk app mounted while allowing daemon-driven session reloads. */
+export function AppHost({
+  bootstrap,
+  hostClient,
+  onQuit = () => process.exit(0),
+  startupNoticeResolver,
+}: {
+  bootstrap: AppBootstrap;
+  hostClient?: HunkHostClient;
+  onQuit?: () => void;
+  startupNoticeResolver?: () => Promise<UpdateNotice | null>;
+}) {
+  const [activeBootstrap, setActiveBootstrap] = useState(bootstrap);
+  const [appVersion, setAppVersion] = useState(0);
+  const startupNoticeText = useStartupUpdateNotice({
+    enabled: !bootstrap.input.options.pager,
+    resolver: startupNoticeResolver,
+  });
+
+  const reloadSession = useCallback(
+    async (nextInput: CliInput, options?: { resetApp?: boolean; sourcePath?: string }) => {
+      // Re-run the same startup normalization pipeline used on first launch so reloads honor
+      // runtime defaults and config layering instead of assuming `nextInput` is already final.
+      // `sourcePath` matters for daemon-driven reloads that ask Hunk to reopen content from a
+      // different working directory than the process originally started in.
+      const runtimeInput = resolveRuntimeCliInput(nextInput);
+      const configuredInput = resolveConfiguredCliInput(runtimeInput, {
+        cwd: options?.sourcePath,
+      }).input;
+      const nextBootstrap = await loadAppBootstrap(configuredInput, {
+        cwd: options?.sourcePath,
+      });
+      const nextSnapshot = createInitialSessionSnapshot(nextBootstrap);
+
+      let sessionId = "local-session";
+      if (hostClient) {
+        // Keep the daemon-facing session registration in sync with whatever the UI is about to
+        // show. Replacing both registration and snapshot here means external session commands see
+        // the new source, title, and selection baseline immediately after reload.
+        const nextRegistration = updateSessionRegistration(
+          hostClient.getRegistration(),
+          nextBootstrap,
+        );
+        sessionId = nextRegistration.sessionId;
+        hostClient.replaceSession(nextRegistration, nextSnapshot);
+      }
+
+      setActiveBootstrap(nextBootstrap);
+      if (options?.resetApp !== false) {
+        // Bumping the key forces a full App remount. Callers that pass `resetApp: false` get a
+        // soft reload that preserves in-memory UI state like selection, filter text, and pane size.
+        setAppVersion((current) => current + 1);
+      }
+
+      return {
+        sessionId,
+        inputKind: nextBootstrap.input.kind,
+        title: nextBootstrap.changeset.title,
+        sourceLabel: nextBootstrap.changeset.sourceLabel,
+        fileCount: nextBootstrap.changeset.files.length,
+        selectedFilePath: nextSnapshot.selectedFilePath,
+        selectedHunkIndex: nextSnapshot.selectedHunkIndex,
+      };
+    },
+    [hostClient],
+  );
+
+  return (
+    <App
+      key={appVersion}
+      bootstrap={activeBootstrap}
+      hostClient={hostClient}
+      noticeText={startupNoticeText}
+      onQuit={onQuit}
+      onReloadSession={reloadSession}
+    />
+  );
+}

test/app-interactions.test.tsx

@@ -10,7 +10,7 @@ import type { HunkSessionRegistration, SessionServerMessage } from "../src/mcp/t
 import type { AppBootstrap, DiffFile, LayoutMode } from "../src/core/types";
 
 const { loadAppBootstrap } = await import("../src/core/loaders");
-const { AppHost } = await import("../src/ui/App");
+const { AppHost } = await import("../src/ui/AppHost");
 
 function createDiffFile(
   id: string,

test/app-responsive.test.tsx

@@ -4,7 +4,7 @@ import { parseDiffFromFile } from "@pierre/diffs";
 import { act } from "react";
 import type { AppBootstrap, DiffFile, LayoutMode } from "../src/core/types";
 
-const { AppHost } = await import("../src/ui/App");
+const { AppHost } = await import("../src/ui/AppHost");
 
 function createDiffFile(
   id: string,

test/ui-components.test.tsx

@@ -5,7 +5,7 @@ import { act, createRef, type ReactNode } from "react";
 import type { AppBootstrap, DiffFile } from "../src/core/types";
 import { resolveTheme } from "../src/ui/themes";
 
-const { AppHost } = await import("../src/ui/App");
+const { AppHost } = await import("../src/ui/AppHost");
 const { buildSidebarEntries } = await import("../src/ui/lib/files");
 const { HelpDialog } = await import("../src/ui/components/chrome/HelpDialog");
 const { FilesPane } = await import("../src/ui/components/panes/FilesPane");

test/ui-scroll-regression.test.tsx

@@ -6,7 +6,7 @@ import type { AppBootstrap } from "../src/core/types";
 
 mock.restore();
 
-const { AppHost } = await import("../src/ui/App");
+const { AppHost } = await import("../src/ui/AppHost");
 
 function createScrollBootstrap(): AppBootstrap {
   const before = Array.from(

test/vertical-scrollbar.test.tsx

@@ -4,7 +4,7 @@ import { parseDiffFromFile } from "@pierre/diffs";
 import { act } from "react";
 import type { AppBootstrap, DiffFile } from "../src/core/types";
 
-const { AppHost } = await import("../src/ui/App");
+const { AppHost } = await import("../src/ui/AppHost");
 
 function createDiffFile(id: string, path: string, before: string, after: string): DiffFile {
   const metadata = parseDiffFromFile(