Archived chats accept mutations (messages, edits, queued-message
promotions, tool-result submissions) via the API, causing them to
re-enter the processing pipeline. This violates the hard-stop
design intent from PR #23758.
Add archived checks at three layers:
- HTTP handlers (postChatMessages, patchChatMessage,
promoteChatQueuedMessage, postChatToolResults): return 400
after auth so callers get a clear error.
- Daemon functions (SendMessage, EditMessage, PromoteQueued,
SubmitToolResults): return ErrChatArchived after row lock,
guarding against future callers that bypass the handler.
- AcquireChats SQL: filter out archived chats so they are never
acquired for processing.
Fixes CODAGT-245
Mathias Fredriksson
f8fe5d680b