opencode/packages/ai/src/protocols/open-responses.ts
2026-07-26 20:16:58 -04:00

1070 lines
40 KiB
TypeScript

import { Effect, Schema } from "effect"
import type { Content } from "@opencode-ai/schema/tool"
import { HttpTransport } from "../route/transport"
import { Protocol } from "../route/protocol"
import {
LLMError,
LLMEvent,
Usage,
type FinishReason,
type JsonSchema,
type LLMRequest,
type MediaPart,
type ProviderMetadata,
type ReasoningPart,
type TextPart,
type ToolCallPart,
type ToolDefinition,
type ToolResultPart,
} from "../schema"
import { JsonObject, optionalArray, optionalNull, ProviderShared } from "./shared"
import { classifyProviderFailure } from "../provider-error"
import { OpenResponsesOptions } from "./utils/open-responses-options"
import { Lifecycle } from "./utils/lifecycle"
import { ToolSchemaProjection } from "./utils/tool-schema"
import { ToolStream } from "./utils/tool-stream"
const ADAPTER = "open-responses"
const NAME = "Open Responses"
const MEDIA_MIMES = new Set<string>([...ProviderShared.IMAGE_MIMES, ...ProviderShared.PDF_MIMES])
export const PATH = "/responses"
// =============================================================================
// Request Body Schema
// =============================================================================
const OpenResponsesInputText = Schema.Struct({
type: Schema.tag("input_text"),
text: Schema.String,
})
const OpenResponsesInputImage = Schema.Struct({
type: Schema.tag("input_image"),
image_url: Schema.String,
})
const OpenResponsesInputFile = Schema.Struct({
type: Schema.tag("input_file"),
filename: Schema.String,
file_data: Schema.String,
mime_type: Schema.optional(Schema.String),
})
const MediaInput = Schema.Union([OpenResponsesInputImage, OpenResponsesInputFile])
export type MediaInput = Schema.Schema.Type<typeof MediaInput>
const OpenResponsesInputContent = Schema.Union([OpenResponsesInputText, MediaInput])
const OpenResponsesOutputText = Schema.Struct({
type: Schema.tag("output_text"),
text: Schema.String,
})
export const MessagePhase = Schema.Literals(["commentary", "final_answer"])
type MessagePhase = Schema.Schema.Type<typeof MessagePhase>
const OpenResponsesReasoningSummaryText = Schema.Struct({
type: Schema.tag("summary_text"),
text: Schema.String,
})
const OpenResponsesReasoningItem = Schema.Struct({
type: Schema.tag("reasoning"),
id: Schema.optionalKey(Schema.String),
summary: Schema.Array(OpenResponsesReasoningSummaryText),
encrypted_content: optionalNull(Schema.String),
})
const OpenResponsesItemReference = Schema.Struct({
type: Schema.tag("item_reference"),
id: Schema.String,
})
// `function_call_output.output` accepts either a plain string or an ordered
// array of content items so tools can return images and files in addition to text.
// https://www.openresponses.org/reference
const OpenResponsesFunctionCallOutputContent = Schema.Union([
OpenResponsesInputText,
OpenResponsesInputImage,
OpenResponsesInputFile,
])
const OpenResponsesFunctionCallOutput = Schema.Union([
Schema.String,
Schema.Array(OpenResponsesFunctionCallOutputContent),
])
export const InputItem = Schema.Union([
Schema.Struct({ role: Schema.tag("system"), content: Schema.String }),
Schema.Struct({ role: Schema.tag("user"), content: Schema.Array(OpenResponsesInputContent) }),
Schema.Struct({
role: Schema.tag("assistant"),
content: Schema.Array(OpenResponsesOutputText),
phase: Schema.optionalKey(MessagePhase),
}),
OpenResponsesReasoningItem,
OpenResponsesItemReference,
Schema.Struct({
type: Schema.tag("function_call"),
call_id: Schema.String,
name: Schema.String,
arguments: Schema.String,
}),
Schema.Struct({
type: Schema.tag("function_call_output"),
call_id: Schema.String,
output: OpenResponsesFunctionCallOutput,
}),
])
type OpenResponsesInputItem = Schema.Schema.Type<typeof InputItem>
type LoweredInputItem =
| OpenResponsesInputItem
| {
readonly role: "assistant"
readonly content: ReadonlyArray<{ readonly type: "output_text"; readonly text: string }>
readonly phase?: MessagePhase | null
}
// Mutable counterpart of the schema reasoning item so `lowerMessages` can fold
// multiple streamed summary parts into the same item before flushing.
type OpenResponsesReasoningInput = {
type: "reasoning"
id: string
summary: Array<{ type: "summary_text"; text: string }>
encrypted_content?: string | null
}
type OpenResponsesReasoningReplay = Omit<OpenResponsesReasoningInput, "id">
export const Tool = Schema.Struct({
type: Schema.tag("function"),
name: Schema.String,
description: Schema.String,
parameters: JsonObject,
strict: Schema.optional(Schema.Boolean),
})
export const ToolChoice = Schema.Union([
Schema.Literals(["auto", "none", "required"]),
Schema.Struct({ type: Schema.tag("function"), name: Schema.String }),
])
// Fields shared between the HTTP body and the WebSocket `response.create`
// message. The HTTP body adds `stream: true`; the WebSocket message adds
// `type: "response.create"`. Defining the shared shape once keeps the two
// transports in sync without a destructure-and-strip dance.
export const coreFields = {
model: Schema.String,
input: Schema.Array(InputItem),
instructions: Schema.optional(Schema.String),
tools: optionalArray(Tool),
tool_choice: Schema.optional(ToolChoice),
store: Schema.optional(Schema.Boolean),
service_tier: Schema.optional(OpenResponsesOptions.ServiceTierSchema),
prompt_cache_key: Schema.optional(Schema.String),
include: optionalArray(OpenResponsesOptions.ResponseIncludableSchema),
reasoning: Schema.optional(
Schema.Struct({
effort: Schema.optional(OpenResponsesOptions.ReasoningEffort),
summary: Schema.optional(Schema.Literals(["auto", "concise", "detailed"])),
}),
),
text: Schema.optional(
Schema.Struct({
verbosity: Schema.optional(OpenResponsesOptions.TextVerbositySchema),
}),
),
max_output_tokens: Schema.optional(Schema.Number),
temperature: Schema.optional(Schema.Number),
top_p: Schema.optional(Schema.Number),
}
const OpenResponsesBody = Schema.Struct({
...coreFields,
stream: Schema.Literal(true),
})
export type OpenResponsesBody = Schema.Schema.Type<typeof OpenResponsesBody>
const OpenResponsesUsage = Schema.Struct({
input_tokens: Schema.optional(Schema.Number),
input_tokens_details: optionalNull(
Schema.Struct({
cached_tokens: Schema.optional(Schema.Number),
cache_write_tokens: Schema.optional(Schema.Number),
}),
),
output_tokens: Schema.optional(Schema.Number),
output_tokens_details: optionalNull(Schema.Struct({ reasoning_tokens: Schema.optional(Schema.Number) })),
total_tokens: Schema.optional(Schema.Number),
})
type OpenResponsesUsage = Schema.Schema.Type<typeof OpenResponsesUsage>
export const StreamItem = Schema.StructWithRest(
Schema.Struct({
type: Schema.String,
id: Schema.optional(Schema.String),
call_id: Schema.optional(Schema.String),
name: Schema.optional(Schema.String),
arguments: Schema.optional(Schema.String),
encrypted_content: optionalNull(Schema.String),
}),
[Schema.Record(Schema.String, Schema.Unknown)],
)
export type StreamItem = Schema.Schema.Type<typeof StreamItem>
// The Responses schema puts streaming error details at the top level and
// response failures under `response.error`. WebSocket failures use an
// event-level `error` envelope, so accept all three shapes here.
// https://www.openresponses.org/specification
const OpenResponsesErrorPayload = Schema.Struct({
code: optionalNull(Schema.String),
message: optionalNull(Schema.String),
param: optionalNull(Schema.String),
})
export const Event = Schema.StructWithRest(
Schema.Struct({
type: Schema.String,
delta: Schema.optional(Schema.String),
text: Schema.optional(Schema.String),
item_id: Schema.optional(Schema.String),
summary_index: Schema.optional(Schema.Number),
item: Schema.optional(StreamItem),
response: Schema.optional(
Schema.StructWithRest(
Schema.Struct({
id: Schema.optional(Schema.String),
service_tier: optionalNull(Schema.String),
incomplete_details: optionalNull(Schema.Struct({ reason: Schema.optional(Schema.String) })),
usage: optionalNull(OpenResponsesUsage),
error: optionalNull(OpenResponsesErrorPayload),
}),
[Schema.Record(Schema.String, Schema.Unknown)],
),
),
code: optionalNull(Schema.String),
message: Schema.optional(Schema.String),
param: optionalNull(Schema.String),
error: optionalNull(OpenResponsesErrorPayload),
}),
[Schema.Record(Schema.String, Schema.Unknown)],
)
export type Event = Schema.Schema.Type<typeof Event>
export interface Extension {
readonly id: string
readonly name: string
readonly lowerMedia?: (input: {
readonly part: MediaPart
readonly media: ProviderShared.ValidatedMedia
readonly request: LLMRequest
}) => MediaInput | undefined
readonly messagePhase?: (value: unknown) => MessagePhase | null | undefined
}
const BASE: Extension = { id: ADAPTER, name: NAME }
export interface ParserState {
readonly id: string
readonly name: string
readonly providerMetadataKey: string
readonly tools: ToolStream.State<string>
readonly hasFunctionCall: boolean
readonly lifecycle: Lifecycle.State
readonly messageItems: ReadonlySet<string>
readonly messagePhase: (value: unknown) => MessagePhase | null | undefined
readonly messagePhases: Readonly<Record<string, MessagePhase | null>>
readonly reasoningItems: Readonly<Record<string, ReasoningStreamItem>>
readonly store: boolean | undefined
}
type ReasoningSummaryStatus = "active" | "can-conclude" | "concluded"
interface ReasoningStreamItem {
readonly encryptedContent: string | null | undefined
// Keyed by the wire protocol's numeric `summary_index`. JS object keys coerce to
// strings, but typing the map as `Record<number, ...>` documents intent
// and matches the wire field.
readonly summaryParts: Readonly<Record<number, ReasoningSummaryStatus>>
}
// =============================================================================
// Request Lowering
// =============================================================================
export const lowerTool = Effect.fn("OpenResponses.lowerTool")(function* (
protocolName: string,
tool: ToolDefinition,
inputSchema: JsonSchema,
) {
if (tool.native !== undefined)
return yield* ProviderShared.invalidRequest(`${protocolName} does not support provider-native tool ${tool.name}`)
return {
type: "function" as const,
name: tool.name,
description: tool.description,
parameters: ToolSchemaProjection.responses(inputSchema),
// TODO: Read this from Responses tool options so direct LLM callers can opt into strict schemas.
strict: false,
}
})
export const lowerToolChoice = (protocolName: string, toolChoice: NonNullable<LLMRequest["toolChoice"]>) =>
ProviderShared.matchToolChoice(protocolName, toolChoice, {
auto: () => "auto" as const,
none: () => "none" as const,
required: () => "required" as const,
tool: (toolName) => ({ type: "function" as const, name: toolName }),
})
const lowerToolCall = (part: ToolCallPart): OpenResponsesInputItem => ({
type: "function_call",
call_id: part.id,
name: part.name,
arguments: ProviderShared.encodeJson(part.input),
})
const lowerReasoning = (part: ReasoningPart, providerMetadataKey: string): OpenResponsesReasoningInput | undefined => {
const metadata = part.providerMetadata?.[providerMetadataKey]
if (!ProviderShared.isRecord(metadata) || typeof metadata.itemId !== "string" || metadata.itemId.length === 0)
return undefined
const encryptedContent =
typeof metadata.reasoningEncryptedContent === "string" || metadata.reasoningEncryptedContent === null
? metadata.reasoningEncryptedContent
: undefined
return {
type: "reasoning",
id: metadata.itemId,
summary: part.text.length > 0 ? [{ type: "summary_text", text: part.text }] : [],
encrypted_content: encryptedContent,
}
}
const hostedToolItemID = (part: ToolResultPart, providerMetadataKey: string) => {
const metadata = part.providerMetadata?.[providerMetadataKey]
return ProviderShared.isRecord(metadata) && typeof metadata.itemId === "string" && metadata.itemId.length > 0
? metadata.itemId
: undefined
}
const lowerMedia = Effect.fn("OpenResponses.lowerMedia")(function* (
part: MediaPart,
request: LLMRequest,
extension: Extension,
) {
const media = yield* ProviderShared.validateMedia(extension.name, part, MEDIA_MIMES)
const extended = extension.lowerMedia?.({ part, media, request })
if (extended) return extended
if (media.mime === "application/pdf") {
return {
type: "input_file" as const,
filename: part.filename ?? "document.pdf",
file_data: media.dataUrl,
}
}
return { type: "input_image" as const, image_url: media.dataUrl }
})
const lowerUserContent = Effect.fn("OpenResponses.lowerUserContent")(function* (
part: LLMRequest["messages"][number]["content"][number],
request: LLMRequest,
extension: Extension,
) {
if (part.type === "text") return { type: "input_text" as const, text: part.text }
if (part.type === "media") return yield* lowerMedia(part, request, extension)
return yield* ProviderShared.unsupportedContent(extension.name, "user", ["text", "media"])
})
// Tool results may carry structured text, images, and files. Keep media as provider-native
// content instead of JSON-stringifying base64 into a prompt string.
const lowerToolResultContentItem = Effect.fn("OpenResponses.lowerToolResultContentItem")(function* (
item: Content,
request: LLMRequest,
extension: Extension,
) {
if (item.type === "text") return { type: "input_text" as const, text: item.text }
return yield* lowerMedia(
{ type: "media", mediaType: item.mime, data: item.uri, filename: item.name },
request,
extension,
)
})
const lowerToolResultOutput = Effect.fn("OpenResponses.lowerToolResultOutput")(function* (
part: ToolResultPart,
request: LLMRequest,
extension: Extension,
) {
// Text/json/error results are encoded as a plain string for backward
// compatibility with existing cassettes and provider expectations.
if (part.result.type !== "content") return ProviderShared.toolResultText(part)
// Preserve the narrowed array element type when compiled through a consumer package.
const content: ReadonlyArray<Content> = part.result.value
return yield* Effect.forEach(content, (item) => lowerToolResultContentItem(item, request, extension))
})
const lowerMessages = Effect.fn("OpenResponses.lowerMessages")(function* (request: LLMRequest, extension: Extension) {
const system: LoweredInputItem[] =
request.system.length === 0 ? [] : [{ role: "system", content: ProviderShared.joinText(request.system) }]
const input: LoweredInputItem[] = [...system]
const store = OpenResponsesOptions.resolve(request).store
const providerMetadataKey = request.model.route.providerMetadataKey ?? "openresponses"
for (const message of request.messages) {
if (message.role === "system") {
const part = yield* ProviderShared.wrappedSystemUpdate(extension.name, message)
const previous = input.at(-1)
if (previous && "role" in previous && previous.role === "user")
input[input.length - 1] = {
role: "user",
content: [...previous.content, { type: "input_text", text: part.text }],
}
else input.push({ role: "user", content: [{ type: "input_text", text: part.text }] })
continue
}
if (message.role === "user") {
input.push({
role: "user",
content: yield* Effect.forEach(message.content, (part) => lowerUserContent(part, request, extension)),
})
continue
}
if (message.role === "assistant") {
const content: TextPart[] = []
const reasoningItems: Record<string, OpenResponsesReasoningReplay> = {}
const reasoningReferences = new Set<string>()
const hostedToolReferences = new Set<string>()
const flushText = () => {
if (content.length === 0) return
const groups = content.reduce<Array<{ phase: MessagePhase | null | undefined; parts: TextPart[] }>>(
(groups, part) => {
const metadata = part.providerMetadata?.[providerMetadataKey]
const phase =
ProviderShared.isRecord(metadata)
? messagePhase(metadata.phase, extension)
: undefined
const group = groups.at(-1)
if (group && group.phase === phase) group.parts.push(part)
else groups.push({ phase, parts: [part] })
return groups
},
[],
)
input.push(
...groups.map((group) => ({
role: "assistant" as const,
content: group.parts.map((part) => ({ type: "output_text" as const, text: part.text })),
...(group.phase === undefined ? {} : { phase: group.phase }),
})),
)
content.splice(0, content.length)
}
for (const part of message.content) {
if (part.type === "text") {
content.push(part)
continue
}
if (part.type === "reasoning") {
flushText()
const reasoning = lowerReasoning(part, providerMetadataKey)
if (!reasoning) continue
if (store !== false) {
if (!reasoningReferences.has(reasoning.id)) input.push({ type: "item_reference", id: reasoning.id })
reasoningReferences.add(reasoning.id)
continue
}
const existing = reasoningItems[reasoning.id]
if (existing) {
existing.summary.push(...reasoning.summary)
if (typeof reasoning.encrypted_content === "string")
existing.encrypted_content = reasoning.encrypted_content
continue
}
const replay = {
type: reasoning.type,
summary: reasoning.summary,
encrypted_content: reasoning.encrypted_content,
}
reasoningItems[reasoning.id] = replay
input.push(replay)
continue
}
if (part.type === "tool-call") {
flushText()
if (part.providerExecuted === true) continue
input.push(lowerToolCall(part))
continue
}
if (part.type === "tool-result" && part.providerExecuted === true) {
flushText()
const itemID = hostedToolItemID(part, providerMetadataKey)
if (store !== false && itemID && !hostedToolReferences.has(itemID))
input.push({ type: "item_reference", id: itemID })
if (store === false && part.result.type === "content") {
const content: ReadonlyArray<Content> = part.result.value
input.push({
role: "user",
content: yield* Effect.forEach(content, (item) => lowerToolResultContentItem(item, request, extension)),
})
}
if (itemID) hostedToolReferences.add(itemID)
continue
}
return yield* ProviderShared.unsupportedContent(extension.name, "assistant", [
"text",
"reasoning",
"tool-call",
"tool-result",
])
}
flushText()
continue
}
for (const part of message.content) {
if (!ProviderShared.supportsContent(part, ["tool-result"]))
return yield* ProviderShared.unsupportedContent(extension.name, "tool", ["tool-result"])
input.push({
type: "function_call_output",
call_id: part.id,
output: yield* lowerToolResultOutput(part, request, extension),
})
}
}
// With store:false, Responses APIs only accept previous reasoning items when the
// complete item has encrypted state. Summary blocks for one item may carry
// that state only on the last block, so filter after they have been joined.
return store === false
? input.filter(
(item) => !("type" in item) || item.type !== "reasoning" || typeof item.encrypted_content === "string",
)
: input
})
const lowerOptions = (request: LLMRequest) => {
const options = OpenResponsesOptions.resolve(request)
return {
...(options.instructions ? { instructions: options.instructions } : {}),
...(options.store !== undefined ? { store: options.store } : {}),
...(options.promptCacheKey ? { prompt_cache_key: options.promptCacheKey } : {}),
...(options.include ? { include: options.include } : {}),
...(options.reasoningEffort || options.reasoningSummary
? { reasoning: { effort: options.reasoningEffort, summary: options.reasoningSummary } }
: {}),
...(options.textVerbosity ? { text: { verbosity: options.textVerbosity } } : {}),
...(options.serviceTier ? { service_tier: options.serviceTier } : {}),
}
}
export const fromRequestWithExtension = Effect.fn("OpenResponses.fromRequestWithExtension")(function* (
request: LLMRequest,
extension: Extension,
) {
const generation = request.generation
const toolSchemaCompatibility = request.model.compatibility?.toolSchema
return {
model: request.model.id,
input: yield* lowerMessages(request, extension),
tools:
request.tools.length === 0
? undefined
: yield* Effect.forEach(request.tools, (tool) =>
lowerTool(
extension.name,
tool,
ToolSchemaProjection.modelCompatibility(tool.inputSchema, toolSchemaCompatibility),
),
),
tool_choice: request.toolChoice ? yield* lowerToolChoice(extension.name, request.toolChoice) : undefined,
stream: true as const,
max_output_tokens: generation?.maxTokens,
temperature: generation?.temperature,
top_p: generation?.topP,
...lowerOptions(request),
}
})
const decodeBody = ProviderShared.validateWith(Schema.decodeUnknownEffect(OpenResponsesBody))
export const fromRequest = Effect.fn("OpenResponses.fromRequest")(function* (request: LLMRequest) {
return yield* decodeBody(yield* fromRequestWithExtension(request, BASE))
})
// =============================================================================
// Stream Parsing
// =============================================================================
// Responses APIs report `input_tokens` (inclusive total) with a
// cached-read and cache-write subsets, and `output_tokens` (inclusive total)
// with a `reasoning_tokens` subset. Pass the totals through and derive the
// non-cached breakdown.
const mapUsage = (usage: OpenResponsesUsage | null | undefined, providerMetadataKey: string) => {
if (!usage) return undefined
const cached = usage.input_tokens_details?.cached_tokens
const cacheWrite = usage.input_tokens_details?.cache_write_tokens
const reasoning = usage.output_tokens_details?.reasoning_tokens
const nonCached = ProviderShared.subtractTokens(usage.input_tokens, ProviderShared.sumTokens(cached, cacheWrite))
return new Usage({
inputTokens: usage.input_tokens,
outputTokens: usage.output_tokens,
nonCachedInputTokens: nonCached,
cacheReadInputTokens: cached,
cacheWriteInputTokens: cacheWrite,
reasoningTokens: reasoning,
totalTokens: ProviderShared.totalTokens(usage.input_tokens, usage.output_tokens, usage.total_tokens),
providerMetadata: { [providerMetadataKey]: usage },
})
}
const mapFinishReason = (event: Event, hasFunctionCall: boolean): FinishReason => {
const reason = event.response?.incomplete_details?.reason
if (reason === undefined || reason === null) {
if (hasFunctionCall) return "tool-calls"
if (event.type === "response.incomplete") return "unknown"
return "stop"
}
if (reason === "max_output_tokens") return "length"
if (reason === "content_filter") return "content-filter"
return hasFunctionCall ? "tool-calls" : "unknown"
}
export const providerMetadata = (state: ParserState, metadata: Record<string, unknown>): ProviderMetadata => ({
[state.providerMetadataKey]: metadata,
})
const isReasoningItem = (item: StreamItem): item is StreamItem & { type: "reasoning"; id: string } =>
item.type === "reasoning" && typeof item.id === "string" && item.id.length > 0
export type StepResult = readonly [ParserState, ReadonlyArray<LLMEvent>]
const NO_EVENTS: StepResult["1"] = []
// `response.completed` / `response.incomplete` are clean finishes that emit a
// `finish` event; `response.failed` is a hard failure. All three end the stream,
// so keep this set aligned with `step` and the protocol's terminal predicate.
const TERMINAL_TYPES = new Set(["response.completed", "response.incomplete", "response.failed"])
export const terminal = (event: Event) => TERMINAL_TYPES.has(event.type)
const onOutputTextDelta = (state: ParserState, event: Event, id: string): StepResult => {
if (!event.delta) return [state, NO_EVENTS]
const events: LLMEvent[] = []
const phase = state.messagePhases[id]
const metadata = phase === undefined ? undefined : providerMetadata(state, { phase })
const lifecycle = Lifecycle.textStart(state.lifecycle, events, id, metadata)
return [
{ ...state, lifecycle: Lifecycle.textDelta(lifecycle, events, id, event.delta) },
events,
]
}
const onOutputTextDone = (state: ParserState, event: Event, id: string): StepResult => {
if (state.messageItems.has(id)) {
if (state.lifecycle.text.has(id) || event.text === undefined) return [state, NO_EVENTS]
return onOutputTextDelta(state, { ...event, delta: event.text }, id)
}
const events: LLMEvent[] = []
return [{ ...state, lifecycle: Lifecycle.textEnd(state.lifecycle, events, id) }, events]
}
export const onReasoningDelta = (state: ParserState, event: Event, itemID: string): StepResult => {
if (!event.delta) return [state, NO_EVENTS]
const events: LLMEvent[] = []
const id =
event.summary_index !== undefined || state.reasoningItems[itemID] ? `${itemID}:${event.summary_index ?? 0}` : itemID
return [
{
...state,
lifecycle: Lifecycle.reasoningDelta(state.lifecycle, events, id, event.delta),
},
events,
]
}
export const onReasoningDone = (state: ParserState, _event: Event): StepResult => [state, NO_EVENTS]
const reasoningMetadata = (state: ParserState, item: StreamItem & { id: string }) =>
providerMetadata(state, { itemId: item.id, reasoningEncryptedContent: item.encrypted_content ?? null })
// Responses APIs stream reasoning items in a stable order:
// `output_item.added` (reasoning) →
// `reasoning_summary_part.added` (index=0) →
// `reasoning_summary_text.delta` →
// `reasoning_summary_part.done` (index=0) →
// (repeat for index>0) →
// `output_item.done` (reasoning).
// The handlers below rely on this ordering: `onOutputItemAdded` seeds the
// per-item entry, `onReasoningSummaryPartAdded` for `summary_index === 0`
// short-circuits when the entry already exists, and higher-index handlers
// fold against the same entry. Behaviour for out-of-order events is
// best-effort, not guaranteed.
const onOutputItemAdded = (state: ParserState, event: Event): StepResult => {
const item = event.item
if (item?.type === "message" && item.id)
return [
{
...state,
messageItems: new Set([...state.messageItems, item.id]),
messagePhases: (() => {
const phase = state.messagePhase(item.phase)
return phase === undefined ? state.messagePhases : { ...state.messagePhases, [item.id]: phase }
})(),
},
NO_EVENTS,
]
if (item && isReasoningItem(item)) {
const events: LLMEvent[] = []
return [
{
...state,
lifecycle: Lifecycle.reasoningStart(state.lifecycle, events, `${item.id}:0`, reasoningMetadata(state, item)),
reasoningItems: {
...state.reasoningItems,
[item.id]: { encryptedContent: item.encrypted_content, summaryParts: { 0: "active" } },
},
},
events,
]
}
if (item?.type !== "function_call" || !item.id) return [state, NO_EVENTS]
const metadata = providerMetadata(state, { itemId: item.id })
const events: LLMEvent[] = []
const lifecycle = Lifecycle.stepStart(state.lifecycle, events)
return [
{
...state,
lifecycle,
tools: ToolStream.start(state.tools, item.id, {
id: item.call_id ?? item.id,
name: item.name ?? "",
input: item.arguments ?? "",
providerMetadata: metadata,
}),
},
[
...events,
LLMEvent.toolInputStart({ id: item.call_id ?? item.id, name: item.name ?? "", providerMetadata: metadata }),
],
]
}
const onReasoningSummaryPartAdded = (state: ParserState, event: Event): StepResult => {
if (!event.item_id || event.summary_index === undefined) return [state, NO_EVENTS]
const item = state.reasoningItems[event.item_id] ?? { encryptedContent: undefined, summaryParts: {} }
if (event.summary_index === 0) {
if (state.reasoningItems[event.item_id]) return [state, NO_EVENTS]
const events: LLMEvent[] = []
return [
{
...state,
lifecycle: Lifecycle.reasoningStart(
state.lifecycle,
events,
`${event.item_id}:0`,
providerMetadata(state, { itemId: event.item_id, reasoningEncryptedContent: null }),
),
reasoningItems: {
...state.reasoningItems,
[event.item_id]: { ...item, summaryParts: { 0: "active" } },
},
},
events,
]
}
const events: LLMEvent[] = []
const closed = Object.entries(item.summaryParts)
.filter((entry) => entry[1] === "can-conclude")
.reduce(
(lifecycle, entry) =>
Lifecycle.reasoningEnd(
lifecycle,
events,
`${event.item_id}:${entry[0]}`,
providerMetadata(state, { itemId: event.item_id }),
),
state.lifecycle,
)
return [
{
...state,
lifecycle: Lifecycle.reasoningStart(
closed,
events,
`${event.item_id}:${event.summary_index}`,
providerMetadata(state, { itemId: event.item_id, reasoningEncryptedContent: item.encryptedContent ?? null }),
),
reasoningItems: {
...state.reasoningItems,
[event.item_id]: {
...item,
summaryParts: {
...Object.fromEntries(
Object.entries(item.summaryParts).map((entry) =>
entry[1] === "can-conclude" ? [entry[0], "concluded" as const] : entry,
),
),
[event.summary_index]: "active",
},
},
},
},
events,
]
}
const onReasoningSummaryPartDone = (state: ParserState, event: Event): StepResult => {
if (!event.item_id || event.summary_index === undefined) return [state, NO_EVENTS]
const item = state.reasoningItems[event.item_id]
if (!item) return [state, NO_EVENTS]
const events: LLMEvent[] = []
return [
{
...state,
lifecycle:
state.store !== false
? Lifecycle.reasoningEnd(
state.lifecycle,
events,
`${event.item_id}:${event.summary_index}`,
providerMetadata(state, { itemId: event.item_id }),
)
: state.lifecycle,
reasoningItems: {
...state.reasoningItems,
[event.item_id]: {
...item,
summaryParts: {
...item.summaryParts,
[event.summary_index]: state.store !== false ? "concluded" : "can-conclude",
},
},
},
},
events,
]
}
const onFunctionCallArgumentsDelta = Effect.fn("OpenResponses.onFunctionCallArgumentsDelta")(function* (
state: ParserState,
event: Event,
) {
if (!event.item_id || !event.delta) return [state, NO_EVENTS] satisfies StepResult
const result = ToolStream.appendExisting(
state.id,
state.tools,
event.item_id,
event.delta,
`${state.name} tool argument delta is missing its tool call`,
)
if (ToolStream.isError(result)) return yield* result
const events: LLMEvent[] = []
const lifecycle = result.events.length ? Lifecycle.stepStart(state.lifecycle, events) : state.lifecycle
events.push(...result.events)
return [{ ...state, lifecycle, tools: result.tools }, events] satisfies StepResult
})
const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (state: ParserState, event: Event) {
const item = event.item
if (!item) return [state, NO_EVENTS] satisfies StepResult
if (item.type === "message" && item.id) {
const itemPhase = state.messagePhase(item.phase)
const phase = itemPhase === undefined ? state.messagePhases[item.id] : itemPhase
const events: LLMEvent[] = []
const messageItems = new Set(state.messageItems)
messageItems.delete(item.id)
const { [item.id]: _phase, ...messagePhases } = state.messagePhases
return [
{
...state,
lifecycle: Lifecycle.textEnd(
state.lifecycle,
events,
item.id,
phase === undefined ? undefined : providerMetadata(state, { phase }),
),
messageItems,
messagePhases,
},
events,
] satisfies StepResult
}
if (item.type === "function_call") {
if (!item.id || !item.call_id || !item.name) return [state, NO_EVENTS] satisfies StepResult
const tools = state.tools[item.id]
? state.tools
: ToolStream.start(state.tools, item.id, { id: item.call_id, name: item.name })
const result =
item.arguments === undefined
? yield* ToolStream.finish(state.id, tools, item.id)
: yield* ToolStream.finishWithInput(state.id, tools, item.id, item.arguments)
const events: LLMEvent[] = []
const resultEvents = result.events ?? []
const lifecycle = resultEvents.length ? Lifecycle.stepStart(state.lifecycle, events) : state.lifecycle
events.push(...resultEvents)
return [
{
...state,
lifecycle,
hasFunctionCall:
resultEvents.some((event) => LLMEvent.is.toolCall(event) || LLMEvent.is.toolInputError(event)) ||
state.hasFunctionCall,
tools: result.tools,
},
events,
] satisfies StepResult
}
if (isReasoningItem(item)) {
const events: LLMEvent[] = []
const metadata = reasoningMetadata(state, item)
const reasoningItem = state.reasoningItems[item.id]
if (reasoningItem) {
const lifecycle = Object.entries(reasoningItem.summaryParts)
.filter((entry) => entry[1] === "active" || entry[1] === "can-conclude")
.reduce(
(lifecycle, entry) => Lifecycle.reasoningEnd(lifecycle, events, `${item.id}:${entry[0]}`, metadata),
state.lifecycle,
)
const { [item.id]: _removed, ...reasoningItems } = state.reasoningItems
return [{ ...state, lifecycle, reasoningItems }, events] satisfies StepResult
}
if (!state.lifecycle.reasoning.has(item.id)) {
const lifecycle = Lifecycle.stepStart(state.lifecycle, events)
events.push(LLMEvent.reasoningStart({ id: item.id, providerMetadata: metadata }))
events.push(LLMEvent.reasoningEnd({ id: item.id, providerMetadata: metadata }))
return [{ ...state, lifecycle }, events] satisfies StepResult
}
return [
{ ...state, lifecycle: Lifecycle.reasoningEnd(state.lifecycle, events, item.id, metadata) },
events,
] satisfies StepResult
}
return [state, NO_EVENTS] satisfies StepResult
})
const onResponseFinish = (state: ParserState, event: Event): StepResult => {
const events: LLMEvent[] = []
const lifecycle = Lifecycle.finish(state.lifecycle, events, {
reason: {
normalized: mapFinishReason(event, state.hasFunctionCall),
raw: event.response?.incomplete_details?.reason,
},
usage: mapUsage(event.response?.usage, state.providerMetadataKey),
providerMetadata:
event.response?.id || event.response?.service_tier
? providerMetadata(state, {
responseId: event.response.id,
serviceTier: event.response.service_tier,
})
: undefined,
})
return [{ ...state, lifecycle }, events]
}
// Build a single human-readable message from whatever the provider supplied.
// When both code and message are present, prefix the code so consumers see
// the failure mode (e.g. `rate_limit_exceeded: Slow down`) instead of just
// the bare message — production rate limits and context-length failures used
// to be indistinguishable from generic stream drops.
const providerErrorMessage = (event: Event, fallback: string): string => {
const nested = event.error ?? event.response?.error ?? undefined
const message = event.message || nested?.message || undefined
const code = event.code || nested?.code || undefined
if (message && code) return `${code}: ${message}`
return message || code || fallback
}
const providerError = (state: ParserState, event: Event, fallback: string) => {
const code = event.code || event.error?.code || event.response?.error?.code || undefined
const message = providerErrorMessage(event, fallback)
return new LLMError({
module: state.id,
method: "stream",
reason: classifyProviderFailure({ message, code }),
})
}
export const step = (state: ParserState, event: Event) => {
if (event.type === "response.output_text.delta" || event.type === "response.output_text.done") {
if (!event.item_id) return ProviderShared.eventError(state.id, `${event.type} is missing item_id`)
return Effect.succeed(
event.type === "response.output_text.delta"
? onOutputTextDelta(state, event, event.item_id)
: onOutputTextDone(state, event, event.item_id),
)
}
if (event.type === "response.reasoning.delta" || event.type === "response.reasoning_summary_text.delta") {
if (!event.item_id) return ProviderShared.eventError(state.id, `${event.type} is missing item_id`)
return Effect.succeed(onReasoningDelta(state, event, event.item_id))
}
if (event.type === "response.reasoning.done" || event.type === "response.reasoning_summary_text.done") {
if (!event.item_id) return ProviderShared.eventError(state.id, `${event.type} is missing item_id`)
return Effect.succeed(onReasoningDone(state, event))
}
if (event.type === "response.reasoning_summary_part.added")
return event.item_id
? Effect.succeed(onReasoningSummaryPartAdded(state, event))
: ProviderShared.eventError(state.id, `${event.type} is missing item_id`)
if (event.type === "response.reasoning_summary_part.done")
return event.item_id
? Effect.succeed(onReasoningSummaryPartDone(state, event))
: ProviderShared.eventError(state.id, `${event.type} is missing item_id`)
if (event.type === "response.output_item.added") {
if (event.item?.type === "message" && !event.item.id)
return ProviderShared.eventError(state.id, `${event.type} message is missing id`)
return Effect.succeed(onOutputItemAdded(state, event))
}
if (event.type === "response.function_call_arguments.delta") return onFunctionCallArgumentsDelta(state, event)
if (event.type === "response.output_item.done") {
if (event.item?.type === "message" && !event.item.id)
return ProviderShared.eventError(state.id, `${event.type} message is missing id`)
return onOutputItemDone(state, event)
}
if (event.type === "response.completed" || event.type === "response.incomplete")
return Effect.succeed(onResponseFinish(state, event))
if (event.type === "response.failed") return providerError(state, event, `${state.name} response failed`)
if (event.type === "error") return providerError(state, event, `${state.name} stream error`)
return Effect.succeed<StepResult>([state, NO_EVENTS])
}
// =============================================================================
// Protocol
// =============================================================================
/**
* The provider-neutral Open Responses protocol. Provider-specific Responses
* implementations compose this baseline with their own tools and event variants.
*/
export const initial = (request: LLMRequest, extension: Extension = BASE): ParserState => ({
id: extension.id,
name: extension.name,
providerMetadataKey: request.model.route.providerMetadataKey ?? "openresponses",
hasFunctionCall: false,
tools: ToolStream.empty<string>(),
lifecycle: Lifecycle.initial(),
messageItems: new Set<string>(),
messagePhase: (value) => messagePhase(value, extension),
messagePhases: {},
reasoningItems: {},
store: OpenResponsesOptions.resolve(request).store,
})
const messagePhase = (value: unknown, extension: Extension): MessagePhase | null | undefined => {
if (value === "commentary" || value === "final_answer") return value
return extension.messagePhase?.(value)
}
export const protocol = Protocol.make({
id: ADAPTER,
body: {
schema: OpenResponsesBody,
from: fromRequest,
},
stream: {
event: Protocol.jsonEvent(Event),
initial,
step,
terminal,
},
})
export const httpTransport = HttpTransport.sseJson.with<OpenResponsesBody>()
export * as OpenResponses from "./open-responses"