session: interrupted assistant tool-call turn loses reasoning_content on next request #55104

Summary

Interrupting a running prompt with double Escape leaves the session in a state where the next request fails with:

Upstream request failed: [missing_required_parameter] Missing required parameter:
'messages[152].reasoning_content'. This model needs the reasoning of every
earlier assistant message: send back the 'reasoning_content' returned with that
message.

The interrupted assistant turn contained reasoning + an aborted tool call. On the
following turn OpenCode serializes that earlier assistant message without
reasoning_content, so a reasoning model rejects the whole request and the
session becomes unusable.

Environment

• opencode version: 2.0.28
• OS: Linux 6.12.107+deb13-amd64 (Debian, x86_64)
• Terminal: xterm-256color, COLORTERM=truecolor
• Shell: /bin/bash
• Install/channel: latest release (binary ~/.opencode/bin/opencode)
• Active plugins: none found in config (opencode.jsonc is empty; no plugins configured)
• Model: opencode/cat-jam-free (a reasoning model requiring reasoning_content)

Reproduction

1. Use opencode/cat-jam-free in a session with several assistant turns that include reasoning + tool calls.
2. Start another prompt that executes tools (or streams reasoning).
3. Press Escape twice while that turn is running to interrupt it. The aborted
   assistant message is retained (reasoning + a tool call whose status becomes
   error/aborted).
4. Send a new user message.
5. The request fails with missing_required_parameter: messages[...].reasoning_content.

Expected Behavior

OpenCode should preserve and resend the reasoning for the interrupted assistant
turn (as the model requires for every earlier assistant message), allowing the
session to continue after an interrupt.

Actual Behavior

The request omits reasoning_content for that earlier assistant message and the
provider returns HTTP 400. The session is then stuck: every subsequent turn hits
the same error unless the user switches models/sessions.

Additional Context

• The offending message in the recorded session is an assistant message with
  finish: "error", rawFinish: "tool_calls",
  error.type: "aborted" ("Step interrupted"), containing a reasoning part
  (state.reasoningField = "reasoning_content") plus a single shell tool call
  with status: "error" / error.type: "aborted".
• The error index (messages[152]) maps exactly to that assistant message when
  the assistant+tool history is flattened for the upstream request.
• Logs: ~/.local/share/opencode/log/opencode.log, session
  ses_ecb567d2effeW3uRFAfOgSxand.
• Workaround tried: none beyond abandoning the session; new sessions work.