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/components/chat/ChatInput.tsx

@@ -814,11 +814,17 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
 
     const sendableAttachedFiles = attachedFiles;
 
+    const knownAgentNames = React.useMemo(
+        () => new Set(agents.map((agent) => agent.name.toLowerCase())),
+        [agents]
+    );
+    const knownAgentNamesRef = React.useRef(knownAgentNames);
+    knownAgentNamesRef.current = knownAgentNames;
+
     const hasInlineMentionForHighlight = React.useMemo(() => {
         if (!message || !message.includes('@') || inputMode === 'shell') {
             return false;
         }
-        const knownAgentNames = new Set(agents.map((agent) => agent.name.toLowerCase()));
         const mentionRegex = /@([^\s]+)/g;
         let match: RegExpExecArray | null;
         while ((match = mentionRegex.exec(message)) !== null) {
@@ -839,7 +845,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
             }
         }
         return false;
-    }, [agents, inputMode, message]);
+    }, [inputMode, message, knownAgentNames]);
 
     const highlightedComposerContent = React.useMemo(() => {
         if (!hasInlineMentionForHighlight) {
@@ -847,7 +853,6 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
         }
 
         const parts: Array<{ text: string; mentionKind: 'none' | 'file' | 'agent' }> = [];
-        const knownAgentNames = new Set(agents.map((agent) => agent.name.toLowerCase()));
         const mentionRegex = /@([^\s]+)/g;
         let lastIndex = 0;
         let match: RegExpExecArray | null;
@@ -880,7 +885,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
         }
 
         return parts;
-    }, [agents, hasInlineMentionForHighlight, message]);
+    }, [hasInlineMentionForHighlight, message, knownAgentNames]);
 
     const sanitizeAttachmentsForSend = React.useCallback(
         (files: AttachedFile[] | undefined): AttachedFile[] => (files ?? [])
@@ -900,7 +905,6 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
 
         const clientDirectory = opencodeClient.getDirectory() || '';
         const root = (chatSearchDirectory || clientDirectory).replace(/\\/g, '/').replace(/\/+$/, '');
-        const knownAgentNames = new Set(agents.map((agent) => agent.name.toLowerCase()));
         const seenPaths = new Set<string>();
         const attachments: AttachedFile[] = [];
 
@@ -923,7 +927,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
                 continue;
             }
 
-            if (knownAgentNames.has(mentionPath.toLowerCase())) {
+            if (knownAgentNamesRef.current.has(mentionPath.toLowerCase())) {
                 continue;
             }
 
@@ -970,7 +974,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
             sanitizedText: rawText,
             attachments,
         };
-    }, [agents, chatSearchDirectory]);
+    }, [chatSearchDirectory]);
     const [autocompleteOverlayPosition, setAutocompleteOverlayPosition] = React.useState<AutocompleteOverlayPosition | null>(null);
     const abortTimeoutRef = React.useRef<ReturnType<typeof setTimeout> | null>(null);
     const prevWasAbortedRef = React.useRef(false);
@@ -1670,7 +1674,6 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
             const selectionStart = textarea?.selectionStart ?? message.length;
             const selectionEnd = textarea?.selectionEnd ?? message.length;
             const hasCollapsedSelection = selectionStart === selectionEnd;
-            const knownAgentNames = new Set(agents.map((agent) => agent.name.toLowerCase()));
 
             if (hasCollapsedSelection) {
                 const probeIndex = e.key === 'Backspace' ? selectionStart - 1 : selectionStart;
@@ -1688,7 +1691,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
                     const token = message.slice(tokenStart, tokenEnd);
                     const mentionContent = token.slice(1);
                     const looksLikeFileMention = FILE_MENTION_TOKEN.test(token)
-                        && !knownAgentNames.has(mentionContent.toLowerCase())
+                        && !knownAgentNamesRef.current.has(mentionContent.toLowerCase())
                         && isConfirmedFilePath(mentionContent);
 
                     if (looksLikeFileMention) {