fix(llm): replay OpenAI Responses hosted tool history as native input items #29159

Description

The native OpenAI Responses adapter rejects replayed assistant history that contains provider-executed hosted tool results.

This affects the native @opencode-ai/llm OpenAI Responses path, not the default TS AI SDK path. The failure happens before any network call:

ProviderShared.request: OpenAI Responses assistant messages only support text, reasoning, and tool-call content for now

Root cause: OpenAI Responses hosted tools such as web_search_call are parsed into common tool-call + tool-result events with providerExecuted: true. The tool runtime can later replay those as assistant message content, but openai-responses.ts only lowers assistant text, reasoning, and tool-call parts.

Based on Codex’s Responses handling, hosted tool history should be replayed as native top-level Responses input items, for example:

{
  "type": "web_search_call",
  "id": "ws_1",
  "status": "completed",
  "action": { "type": "search", "query": "effect 4" }
}

Suggested fix: detect matching providerExecuted tool-call + tool-result pairs in lowerMessages, and lower them to native hosted Responses input items (or item_reference when stored state is usable). Malformed or mismatched hosted results should fail with a clear invalid-request error.

Repro branch: https://github.com/gzb1128/opencode/tree/repro/openai-responses-hosted-tool-history

I’d be happy to take this issue and submit a PR if maintainers agree with the direction.

Plugins

N/A

OpenCode version

Current dev checkout: 03bb53c38 (@opencode-ai/llm package version 1.15.10)

Steps to reproduce

1. Check out the repro branch:

git fetch https://github.com/gzb1128/opencode.git repro/openai-responses-hosted-tool-history
git switch --detach FETCH_HEAD

2. Run from packages/llm:

bun test test/provider/openai-responses.test.ts -t "replays provider-executed hosted tool results in assistant history"

Actual result:

ProviderShared.request: OpenAI Responses assistant messages only support text, reasoning, and tool-call content for now

Expected result:

The request should prepare successfully and include the hosted tool as a top-level OpenAI Responses input item, not as assistant tool-result content or generic function_call history.

Screenshot and/or share link

N/A

Operating System

macOS

Terminal

N/A