Summary

• Adds a search bar to the History popover (embedded chat panel tab bar) and the Recent popover (left sidebar Chats section) , the two places past chat threads are listed.
• Adds a search-chat-history in-app agent tool so the chat agent can search the user's own past threads too.
• Search hits both chat_threads.name and chat_messages.content , per feedback from Zach in #cedar-concentrate, title-only search "wouldn't work" for a thread whose title never mentions what's actually inside it (his example: a CSV account upload buried in a message). Any result whose match wasn't in the title shows a snippet of the matching message.

Implementation

• services/chat/search-chat-threads.ts , shared search core, reused by the tRPC route, the agent tool, and (indirectly) both frontend surfaces.
• trpc/routes/chat.ts , new chat.searchThreads query, same SELF-only assertActor gating as getThreads.
• mastra/tools/chat/searchChatHistoryTool.ts , new in-app-only tool, registered on both the granular chat agents and the family-surface Master agent (master-surface.ts) so it works regardless of the cedar-master-agent-families flag state.
• db/migrations/chat_search_trgm.sql , pg_trgm GIN trigram indexes on chat_messages.content and chat_threads.name for ILIKE '%x%' substring search, mirroring the existing crm_email_threads_subject_trgm.sql precedent. Already applied to the dev database.
• Frontend: EmbeddedCedarChat.tsx (History popover) and LeftSidebarContent.tsx (Recent popover) both get a filter field styled per crystallized.md §3.4 (h-9, no rule underneath, placeholder doubling as the panel title), debounced, falling back to the existing thread list when the query is empty.

Test plan

• pnpm --filter @zero/server run types , clean
• pnpm --filter @zero/mail run types , clean
• search-chat-threads.integration.test.ts (real DB): content match with snippet, title match, cross-user isolation , all passing
• Migration applied to dev DB (idx_chat_messages_content_trgm 62MB, idx_chat_threads_name_trgm 1.7MB, both valid)
• Manual: open History/Recent popover, search a thread by content not in its title, confirm the snippet surfaces and clicking switches to it
• Manual: ask the in-app agent to search a past chat and confirm it uses the new tool

🤖 Generated with Claude Code

Confidence Score: 3/5

The PR is not safe to merge until chat-history search works on the Agent SDK harness and stale search results can no longer trigger actions for a previous query; explicit repository-rule violations must also be corrected.

Findings

1.  Harness Omits History Search ▶
2.  Stale Results Remain Actionable ▶
3.  Snippet Query Loads Every Match ▶
4. <img alt="P2" src="https://greptile-static-assets.s3.amazonaws.com/badges/p2.svg?v=9" align="t