Add a `providerExecuted: boolean` flag to `tool-call` and `tool-result`
events plus the persisted `ToolResultPart`. When set, the tool runtime
skips client dispatch (the provider already executed the tool) and folds
both events into the assistant message so the next round's history
carries the call + result for context.
Anthropic: decode `server_tool_use` blocks and the three server tool
result block types (`web_search_tool_result`, `code_execution_tool_result`,
`web_fetch_tool_result`) into `tool-call` / `tool-result` events with
`providerExecuted: true`. Round-trip the same parts back into the
provider when the assistant message is replayed in subsequent requests.
Result block error payloads (`*_tool_result_error`) surface as
`result.type === "error"`.
OpenAI Responses: decode hosted tool items emitted via
`response.output_item.done` (`web_search_call`, `file_search_call`,
`code_interpreter_call`, `computer_use_call`, `image_generation_call`,
`mcp_call`, `local_shell_call`) as `tool-call` + `tool-result` pairs
with `providerExecuted: true`. Each tool's input fields are pulled out
explicitly; the full item is passed through as the result payload so
consumers can read outputs / sources / status without re-decoding.
Tool runtime: extend the dispatch decision so provider-executed
tool-calls bypass the handler lookup, and tool-result events with
`providerExecuted: true` are appended to the assistant content for
round-trip rather than being treated as a separate tool message.
Tests: 7 new deterministic fixtures cover Anthropic decode (success +
error result + round-trip + unknown server tool name), OpenAI Responses
decode (web_search_call, code_interpreter_call), and tool-runtime
skip-dispatch.
AGENTS.md updates the runtime section to describe pass-through behavior
and notes the transport-agnostic design that keeps a future WebSocket
adapter (e.g. OpenAI Codex backend) as a sibling rather than a core
rewrite.
Kit Langton
e1c6bf92fb