perf: reduce re-renders, fix mobile keyboard handling, add chunk load recovery, and improve PATH management (#1028)

* fix: exclude file content from reverted prompt text

Revert and fork now restore only the user's original prompt, not server-injected file content
Uses existing isSyntheticPart helper for type-safe filtering

* fix: keep scrollbar visible when hovering over thumb

* fix: prevent ESC abort from triggering when terminal is focused

* fix: pass directory to permission/question reply calls so approvals actually resolve

* fix: default model selection not responding after Base UI migration

* fix: prevent modal content from shifting and clipping footer buttons

* fix: improve session switching performance and add sub-agent export with prompt collapse

Defer viewport anchor saving to eliminate ~800ms UI freeze when switching sessions
Add export dialog to include sub-agent tasks recursively in markdown export
Add collapse chevron button for expanded user prompts in sticky header

* fix: resolve sidebar scroll and TDZ crash in session sidebar

* perf: reduce CPU overhead and re-renders across chat, layout, and settings

* fix: position collapse button at top of message and prevent ESC abort in terminal

* fix: position collapse button at top and add padding only when expanded

* refactor: extract shared PATH utilities and mobile keyboard hook

* refactor: import shared path-utils in electron, use module-level style constants

- Electron now imports pathLooksUserConfigured/mergePathValues from
  shared path-utils.js instead of inline duplication
- ToolPart collapsedCustomStyle moved from useMemo([]) to module const

* fix: resolve remaining merge conflicts and type errors

- Remove duplicate variable declarations in SessionNodeItem
- Remove orphaned export callback body from conflict resolution
- Fix HelpDialog description -> descriptionKey (i18n rename)

* fix: resolve type-check and lint errors in session-actions.test.ts

- Added missing bun:test type declarations (beforeEach, mock, mock.module)
- Removed unused State import
- Replaced 'as any' casts with proper OpencodeClient and ChildStoreManager types
- Added eslint-disable for unused _ parameter in mock function

* fix PR 1028 export and PATH edge cases

* fix startup retry exhaustion state

* remove opencode package lock change

* fix sub-session rename cancellation

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/web/server/lib/opencode/lifecycle.test.js

@@ -116,4 +116,51 @@ describe('OpenCode lifecycle', () => {
 
     await server.close();
   });
+
+  it('falls back to buildAugmentedPath when buildManagedOpenCodePath is not provided', async () => {
+    delete process.env.OPENCODE_BINARY;
+    const child = createMockChild();
+    spawnMock.mockImplementationOnce(() => {
+      queueMicrotask(() => {
+        child.stdout.emit('data', 'opencode server listening on http://127.0.0.1:45678\n');
+      });
+      return child;
+    });
+
+    const runtime = createRuntime({
+      buildManagedOpenCodePath: undefined,
+      buildAugmentedPath: vi.fn(() => '/home/user/.cargo/bin:/usr/local/bin'),
+    });
+    const server = await runtime.startOpenCode();
+    const [, , options] = spawnMock.mock.calls[0];
+
+    expect(options.env.PATH).toBe('/home/user/.cargo/bin:/usr/local/bin');
+
+    await server.close();
+  });
+
+  it('falls back to process.env.PATH when neither build function is provided', async () => {
+    delete process.env.OPENCODE_BINARY;
+    const originalPath = process.env.PATH;
+    process.env.PATH = '/usr/bin:/bin';
+    const child = createMockChild();
+    spawnMock.mockImplementationOnce(() => {
+      queueMicrotask(() => {
+        child.stdout.emit('data', 'opencode server listening on http://127.0.0.1:45678\n');
+      });
+      return child;
+    });
+
+    const runtime = createRuntime({
+      buildManagedOpenCodePath: undefined,
+      buildAugmentedPath: undefined,
+    });
+    const server = await runtime.startOpenCode();
+    const [, , options] = spawnMock.mock.calls[0];
+
+    expect(options.env.PATH).toBe('/usr/bin:/bin');
+    process.env.PATH = originalPath;
+
+    await server.close();
+  });
 });