Chat Mentions

• When changing app mention syntax or parsing, keep all chat mention paths aligned: shared parsing in src/shared/parse_mention_apps.ts, referenced-app extraction in src/ipc/utils/mention_apps.ts, and Lexical external value sync in src/components/chat/LexicalChatInput.tsx. Saved values like @app:foo.app.com must render back as one mention node, not a shortened mention plus plain text; terminal sentence dots such as @app:foo.app.com. should remain plain text outside the mention node.
• App display names preserve Unicode. Mention-boundary checks must treat Unicode letters, numbers, and combining marks as continuation characters; an app named 应用 must not match the prefix of @app:应用程序 or visible @应用程序.
• App display names may contain reserved-looking punctuation such as @app:. Once a known-name span matches, skip nested prefixes inside it. Lexical may render an unmatched legacy no-space token after an app rename, but backend extraction must continue requiring a current known app name.
• App references are sticky per chat in agent-backed modes only. chats.referenced_app_ids stores them (ids, not paths — apps get renamed and moved), resolveStickyReferencedApps unions the stored set with this prompt's mentions each turn, and ReferencedAppsBar renders them with a detach affordance. Do not make build mode sticky: it injects each referenced app's full codebase into the system prompt, so a carried-over reference silently costs tokens on every later turn. Persist on the chat row rather than re-deriving from message history — compaction rewrites history and would drop the mentions. Detaching (removeChatReferencedApp) and clearing messages both revoke access, so both go through mutateChatAfterDrainingStreams: an in-flight turn already resolved the reference set into its tool context, and would otherwise keep reading the app and persist its pre-removal union back over the write.
• LexicalChatInput must never clear itself on submit — clearing is caller-owned. On a successful submit the caller sets the input value to "" (home's handleSubmit, ChatInput's clearComposerAfterSubmit), which triggers the editor's external-clear effect. A rejected or queued submit (no provider configured → pending first prompt; failed queue mid-stream) must leave the value intact: if the home input is emptied while pendingFirstPromptAtom stays true, the armed auto-resume effect in home.tsx submits the user's next keystroke instead of the original prompt.
• In LexicalChatInput DOM tests, mention decorators render as [data-beautiful-mention="@Name"]; data-lexical-beautiful-mention-* belongs to the node's DOM import/export representation and is not present on the live decorated element.