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/ui/src/lib/exportSession.ts

@@ -5,6 +5,13 @@ import { getRevealLabelKey } from '@/lib/utils';
 
 type SessionMessageRecord = { info: Message; parts: Part[] };
 
+export type ChildSessionExport = {
+  title: string;
+  agent?: string;
+  records: SessionMessageRecord[];
+  children: ChildSessionExport[];
+};
+
 function formatTimestamp(timestamp: number | undefined): string {
   if (typeof timestamp !== 'number' || !Number.isFinite(timestamp)) {
     return '';
@@ -65,9 +72,29 @@ function formatMessageAsMarkdown(record: SessionMessageRecord): string {
   return `${role}\n\n${text}`;
 }
 
+function formatChildSessionAsMarkdown(child: ChildSessionExport, depth: number): string {
+  const heading = '#'.repeat(Math.min(depth + 1, 6));
+  const agentLabel = child.agent ? ` — ${child.agent}` : '';
+  const childHeader = `${heading} Sub-agent: ${child.title}${agentLabel}\n\n---\n\n`;
+
+  const childBody = child.records
+    .map(formatMessageAsMarkdown)
+    .filter(Boolean)
+    .join('\n\n---\n\n');
+
+  const parts = [childHeader + childBody];
+
+  for (const grandchild of child.children) {
+    parts.push(formatChildSessionAsMarkdown(grandchild, depth + 1));
+  }
+
+  return parts.join('\n\n---\n\n');
+}
+
 export function formatSessionAsMarkdown(
   messages: SessionMessageRecord[],
   sessionTitle?: string | null,
+  childSessions?: ChildSessionExport[],
 ): string {
   const title = sessionTitle?.trim() || 'Session';
   const date = new Date().toISOString().split('T')[0];
@@ -79,7 +106,16 @@ export function formatSessionAsMarkdown(
     .filter(Boolean)
     .join('\n\n---\n\n');
 
-  return header + body;
+  let result = header + body;
+
+  if (childSessions && childSessions.length > 0) {
+    const childMarkdown = childSessions
+      .map((child) => formatChildSessionAsMarkdown(child, 1))
+      .join('\n\n---\n\n');
+    result += '\n\n---\n\n' + childMarkdown;
+  }
+
+  return result;
 }
 
 export function downloadAsMarkdown(content: string, filename: string): void {