[FEATURE]: Configuration option to disable message summary generation

[milesfrain]

Feature hasn't been suggested before.

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Describe the enhancement you want to request

Is it possible to opt-out of the additional summarization calls that occur per message? I was hoping to see a configuration option skip these requests.

In this example, I send 2 requests to devstral, and opencode inserts an additional 3 requests for summary generation to haiku. (this is a screenshot of Helicone, which I'm using to monitor requests from opencode)

A summary is requested for every user message. And an additional summary request generates the session title, which is essentially a duplicate of the first message summary request.

I see the session summary in the TUI, but don't see any message summaries. So the message summaries don't seem to be adding any value for TUI users.

The message summaries are used in the web/desktop app, but I'm not using this app, and even if I did, I would prefer to downgrade the message summaries to just the first few words of each message in order to avoid the additional summarization requests.

summarizeMessage is the function that makes these requests. It populates userMsg.summary.title. https://github.com/sst/opencode/blob/f53ebafbab35348b131edee238ec16a848094fa2/packages/opencode/src/session/summary.ts#L64-L111