Thread becomes unrecoverable after hitting 32MB request limit

[charlesvien]

Context

Reported by Cory Watilo in Slack. Cory has a habit of long-running tasks and hit a state where the thread became permanently unusable. Every newly-sent message in the thread returns the same error, even simple follow-ups with no attachments.

Local (not cloud).

Problem

Once a conversation accumulates enough context (likely from image attachments in long threads, e.g. repeated clipboard.png reads), the request payload exceeds the 32MB limit and fails with:

Internal error: Request too large (max 32MB). Try with a smaller file.

Two issues:

1. The thread is bricked: every subsequent message in the same conversation hits the same limit and fails, so the user has no way to recover the thread or continue the work.
2. The error message is misleading: it tells the user to "try with a smaller file" but the user may not have attached any file, the cumulative conversation history (including prior image attachments) is what blew past the limit.

Cory notes Claude Code has the same behavior.

Steps to reproduce

1. Start a local thread.
2. Run a long task that accumulates large context, especially multiple image reads (e.g. repeated clipboard.png attachments).
3. Continue sending messages until the request payload exceeds 32MB.
4. Observe the "Request too large (max 32MB)" error.
5. Send any follow-up message in the same thread, even a short text-only one. It fails with the same error.