feat(codemode): add OpenAPI tool adapter (#35192)

packages/codemode/src/openapi/TODO.md

@@ -0,0 +1,19 @@
+# OpenAPI Follow-ups
+
+The initial adapter intentionally skips operations it cannot execute correctly. Future work may add:
+
+- Cookie parameters, authentication, and cookie-header merging.
+- Matrix, label, space-delimited, pipe-delimited, `allowReserved`, and parameter `content` serialization.
+- External references and complete nested `$defs` support.
+- Relative or templated server URLs and server variables.
+- Base URLs containing query strings or fragments.
+- Runtime response-schema validation and full content negotiation.
+- Binary response values and explicit byte-oriented return types.
+- Request/response projection for `readOnly` and `writeOnly` properties.
+- SSE, WebSocket, and other streaming transports.
+- Recovery of responses rejected by a status-filtering `HttpClient`.
+- Configurable request and response size limits.
+- Adapter-enforced redirect policy independent of the supplied `HttpClient`.
+- Strict UTF-8 and empty-body validation for JSON responses.
+- Compile-time rejection of parameter schemas with nested values unsupported by their serialization style; runtime rejects them before auth resolution.
+- Complete malformed-security-scheme validation and broader auth-combination coverage.

packages/codemode/src/openapi/index.ts

@@ -0,0 +1,130 @@
+import { HttpClient } from "effect/unstable/http"
+import { Tool, type Definition } from "../tool.js"
+import { invoke } from "./runtime.js"
+import {
+  componentDefinitions,
+  inputSchema,
+  isRecord,
+  methods,
+  nonEmptyString,
+  operationInput,
+  operationOutput,
+  operationPath,
+  operationSecurityRequirements,
+  securityRequirements,
+  securitySchemes,
+  specServerUrl,
+  validateBaseUrl,
+} from "./spec.js"
+import type { Operation, Options, Result, Skipped, Tools } from "./types.js"
+
+export type {
+  AuthResolver,
+  Credential,
+  Document,
+  Operation,
+  Options,
+  Result,
+  SecurityScheme,
+  Skipped,
+  Tools,
+} from "./types.js"
+
+/**
+ * Builds a CodeMode tool subtree from an OpenAPI 3.x document, one tool per
+ * operation. Auth is resolved host-side via `auth.resolve` and never
+ * model-visible. Tools require `HttpClient.HttpClient`; unrepresentable
+ * operations land in `skipped`.
+ */
+export const fromSpec = (options: Options): Result => {
+  const document = options.spec
+  const schemes = securitySchemes(document)
+  const defaultSecurity = securityRequirements(document.security)
+  const definitions = componentDefinitions(document)
+  const paths = isRecord(document.paths) ? document.paths : {}
+  const used = new Set<string>()
+  const namespaces = new Set<string>()
+  const skipped: Array<Skipped> = []
+  const tools = Object.create(null) as Tools
+
+  for (const [path, pathValue] of Object.entries(paths)) {
+    if (!isRecord(pathValue)) continue
+    for (const [method, operationValue] of Object.entries(pathValue)) {
+      if (!methods.has(method) || !isRecord(operationValue)) continue
+      const segments = operationPath(method, path, operationValue, used, namespaces)
+      const operation: Operation = {
+        operationId: nonEmptyString(operationValue.operationId),
+        method: method.toUpperCase(),
+        path,
+        summary: nonEmptyString(operationValue.summary),
+        description: nonEmptyString(operationValue.description),
+      }
+      const output = operationOutput(document, operationValue, definitions)
+      if (!output.ok) {
+        skipped.push({ method: operation.method, path, reason: output.reason })
+        continue
+      }
+
+      const resolvedBaseUrl = (() => {
+        if (options.baseUrl !== undefined) return validateBaseUrl(options.baseUrl)
+        if (operationValue.servers !== undefined) return specServerUrl(operationValue)
+        if (pathValue.servers !== undefined) return specServerUrl(pathValue)
+        return specServerUrl(document)
+      })()
+      if (!resolvedBaseUrl.ok) {
+        skipped.push({ method: operation.method, path, reason: resolvedBaseUrl.reason })
+        continue
+      }
+      const parsedInput = operationInput(document, pathValue, operationValue)
+      if (!parsedInput.ok) {
+        skipped.push({ method: operation.method, path, reason: parsedInput.reason })
+        continue
+      }
+      const input = parsedInput.value
+
+      const security = operationSecurityRequirements(operationValue.security, defaultSecurity, schemes)
+      if (!security.ok) {
+        skipped.push({ method: operation.method, path, reason: security.reason })
+        continue
+      }
+      const plan = {
+        operation,
+        url: `${resolvedBaseUrl.value.replace(/\/+$/, "")}${path}`,
+        fields: input.fields,
+        body: input.body,
+        security: security.value,
+        schemes,
+        auth: options.auth,
+        headers: options.headers ?? {},
+      }
+      used.add(segments.join("."))
+      for (const index of segments.slice(0, -1).keys()) namespaces.add(segments.slice(0, index + 1).join("."))
+      setTool(
+        tools,
+        segments,
+        Tool.make({
+          description: operation.description ?? operation.summary ?? `${operation.method} ${path}`,
+          input: inputSchema(input.fields, definitions),
+          output: output.value,
+          run: (input) => invoke(plan, input),
+        }),
+      )
+    }
+  }
+
+  return { tools, skipped }
+}
+
+const setTool = (tools: Tools, path: ReadonlyArray<string>, definition: Definition<HttpClient.HttpClient>): void => {
+  const [head, ...rest] = path
+  if (head === undefined) return
+  if (rest.length === 0) {
+    tools[head] = definition
+    return
+  }
+  const child = tools[head]
+  if (child === undefined || !isRecord(child) || child._tag === "CodeModeTool") {
+    tools[head] = Object.create(null) as Tools
+  }
+  setTool(tools[head] as Tools, rest, definition)
+}

packages/codemode/src/openapi/runtime.ts

@@ -0,0 +1,324 @@
+import { Effect, Option, Schema, Stream } from "effect"
+import { HttpClient, HttpClientRequest, HttpClientResponse, type HttpMethod } from "effect/unstable/http"
+import { ToolError, toolError } from "../tool-error.js"
+import { isRecord, own } from "./spec.js"
+import type { AppliedAuth, Credential, Plan, SecurityScheme } from "./types.js"
+
+const decodeJson = Schema.decodeUnknownOption(Schema.UnknownFromJsonString)
+const maxErrorBodyChars = 1_024
+const maxResponseBodyBytes = 50 * 1024 * 1024
+
+export const invoke = (plan: Plan, input: unknown): Effect.Effect<unknown, unknown, HttpClient.HttpClient> =>
+  Effect.gen(function* () {
+    const value = isRecord(input) ? input : {}
+
+    let request = yield* buildRequest(plan, value)
+
+    const auth = yield* resolveAuth(plan)
+    for (const [name, item] of Object.entries(auth.query)) {
+      request = HttpClientRequest.setUrlParam(request, name, item)
+    }
+    request = HttpClientRequest.setHeaders(request, auth.headers)
+
+    const client = yield* HttpClient.HttpClient
+    const response = yield* client
+      .execute(request)
+      .pipe(
+        Effect.catch((cause) =>
+          Effect.fail(toolError(`${plan.operation.method} ${plan.operation.path} failed: transport error`, cause)),
+        ),
+      )
+    const text = yield* readResponseBody(response, plan)
+    const mediaType = response.headers["content-type"]?.split(";")[0]?.trim().toLowerCase()
+    const json = mediaType === "application/json" || mediaType?.endsWith("+json") === true
+    const decoded = text === "" ? Option.some(null) : json ? decodeJson(text) : Option.none()
+    const parsed = json ? Option.getOrElse(decoded, () => text) : text === "" ? null : text
+    if (response.status < 200 || response.status >= 300) {
+      const rendered = typeof parsed === "string" ? parsed : (JSON.stringify(parsed) ?? "")
+      const summary =
+        rendered === "" || rendered === "null"
+          ? "no response body"
+          : rendered.length > maxErrorBodyChars
+            ? `${rendered.slice(0, maxErrorBodyChars)}...`
+            : rendered
+      return yield* Effect.fail(
+        toolError(`${plan.operation.method} ${plan.operation.path} failed with HTTP ${response.status}: ${summary}`),
+      )
+    }
+    if (json && Option.isNone(decoded)) {
+      return yield* Effect.fail(
+        toolError(`${plan.operation.method} ${plan.operation.path} returned malformed JSON.`),
+      )
+    }
+    return parsed
+  })
+
+const buildRequest = (
+  plan: Plan,
+  input: Readonly<Record<string, unknown>>,
+): Effect.Effect<HttpClientRequest.HttpClientRequest, ToolError> =>
+  Effect.gen(function* () {
+    // Validate every model-controlled value before auth resolution, which may refresh tokens.
+    const url = buildUrl(plan, input)
+    if (url instanceof ToolError) return yield* Effect.fail(url)
+    const missing = plan.fields.find(
+      (field) => field.required && field.location !== "path" && own(input, field.inputName) === undefined,
+    )
+    if (missing !== undefined) {
+      const label = missing.location === "body" ? "body field" : `${missing.location} parameter`
+      return yield* Effect.fail(toolError(`Missing required ${label} '${missing.inputName}'.`))
+    }
+
+    let request = HttpClientRequest.make(plan.operation.method as HttpMethod.HttpMethod)(url)
+    for (const field of plan.fields) {
+      if (field.location !== "query") continue
+      const item = own(input, field.inputName)
+      if (item === undefined) continue
+      const serialized = serializeQuery(request, field, item)
+      if (serialized instanceof ToolError) return yield* Effect.fail(serialized)
+      request = serialized
+    }
+
+    // Host headers first, then declared header parameters.
+    request = HttpClientRequest.setHeaders(request, plan.headers)
+    for (const field of plan.fields) {
+      if (field.location !== "header") continue
+      const item = own(input, field.inputName)
+      if (item === undefined) continue
+      const serialized = serializeSimple(field, item, String)
+      if (serialized instanceof ToolError) return yield* Effect.fail(serialized)
+      request = HttpClientRequest.setHeader(request, field.name, serialized)
+    }
+
+    const setBody = (value: unknown, mediaType: string) =>
+      HttpClientRequest.bodyJson(request, value).pipe(
+        Effect.map((next) => HttpClientRequest.setHeader(next, "content-type", mediaType)),
+        Effect.mapError((cause) =>
+          toolError(`Invalid JSON body for ${plan.operation.method} ${plan.operation.path}.`, cause),
+        ),
+      )
+    if (plan.body?.mode === "value") {
+      const field = plan.fields.find((field) => field.location === "body")
+      const body = field === undefined ? undefined : own(input, field.inputName)
+      if (body !== undefined) request = yield* setBody(body, plan.body.mediaType)
+    }
+    if (plan.body?.mode === "object") {
+      const entries = plan.fields.flatMap((field) => {
+        if (field.location !== "body") return []
+        const item = own(input, field.inputName)
+        return item === undefined ? [] : [[field.name, item] as const]
+      })
+      if (plan.body.required || entries.length > 0) {
+        request = yield* setBody(Object.fromEntries(entries), plan.body.mediaType)
+      }
+    }
+    return request
+  })
+
+const resolveAuth = (plan: Plan): Effect.Effect<AppliedAuth, unknown> =>
+  Effect.gen(function* () {
+    const none: AppliedAuth = { headers: {}, query: {} }
+    if (plan.security.length === 0) return none
+
+    const unavailable: Array<string> = []
+    alternatives: for (const requirement of plan.security) {
+      const names = Object.keys(requirement)
+      if (names.length === 0) return none
+      const credentials: Array<readonly [string, SecurityScheme, Credential]> = []
+      for (const name of names) {
+        const scheme = own(plan.schemes, name)
+        if (scheme === undefined || plan.auth === undefined) {
+          unavailable.push(name)
+          continue alternatives
+        }
+        const credential = yield* plan.auth.resolve({
+          name,
+          definition: scheme,
+          scopes: requirement[name] ?? [],
+          operation: plan.operation,
+        })
+        if (credential === undefined) {
+          unavailable.push(name)
+          continue alternatives
+        }
+        credentials.push([name, scheme, credential])
+      }
+      const applied = applyCredentials(credentials)
+      return applied instanceof ToolError ? yield* Effect.fail(applied) : applied
+    }
+
+    return yield* Effect.fail(
+      toolError(
+        `${plan.operation.method} ${plan.operation.path} requires authentication; no credential available for: ${[...new Set(unavailable)].join(", ")}.`,
+      ),
+    )
+  })
+
+const applyCredentials = (
+  credentials: ReadonlyArray<readonly [string, SecurityScheme, Credential]>,
+): AppliedAuth | ToolError => {
+  const headers = new Map<string, string>()
+  const query = new Map<string, string>()
+  const add = (carrier: "header" | "query", name: string, value: string): ToolError | undefined => {
+    const target = carrier === "header" ? headers : query
+    if (target.has(name)) return toolError(`Authentication resolves multiple credentials for ${carrier} '${name}'.`)
+    target.set(name, value)
+  }
+  for (const [name, definition, credential] of credentials) {
+    if (credential.type === "bearer") {
+      const duplicate = add("header", "authorization", `Bearer ${credential.token}`)
+      if (duplicate !== undefined) return duplicate
+      continue
+    }
+    if (credential.type === "basic") {
+      // Buffer instead of btoa: btoa throws on non-Latin-1 credentials.
+      const duplicate = add(
+        "header",
+        "authorization",
+        `Basic ${Buffer.from(`${credential.username}:${credential.password}`, "utf8").toString("base64")}`,
+      )
+      if (duplicate !== undefined) return duplicate
+      continue
+    }
+    if (credential.type === "header") {
+      const duplicate = add("header", credential.name.toLowerCase(), credential.value)
+      if (duplicate !== undefined) return duplicate
+      continue
+    }
+    // apiKey: the carrier comes from the scheme declaration.
+    if (definition.type !== "apiKey") {
+      return toolError(
+        `Security scheme '${name}' is not an apiKey scheme; resolve a bearer, basic, or header credential for it.`,
+      )
+    }
+    if (definition.in === "cookie") return toolError(`Cookie authentication '${name}' is not supported.`)
+    const parameter = definition.in === "header" ? definition.name.toLowerCase() : definition.name
+    const duplicate = add(definition.in, parameter, credential.value)
+    if (duplicate !== undefined) return duplicate
+  }
+  return { headers: Object.fromEntries(headers), query: Object.fromEntries(query) }
+}
+
+const buildUrl = (plan: Plan, input: Readonly<Record<string, unknown>>): string | ToolError => {
+  let url = plan.url
+  for (const field of plan.fields) {
+    if (field.location !== "path") continue
+    const item = own(input, field.inputName)
+    if (item === undefined) {
+      return toolError(`Missing required path parameter '${field.inputName}'.`)
+    }
+    const fieldValue = serializeSimple(field, item, (value) =>
+      encodeURIComponent(value).replace(/[!'()*]/g, (character) =>
+        `%${character.charCodeAt(0).toString(16).toUpperCase()}`,
+      ),
+    )
+    if (fieldValue instanceof ToolError) return fieldValue
+    // '.'/'..' survive encoding and URL normalization collapses them, letting a
+    // model-supplied value retarget the request to a different endpoint.
+    if (fieldValue === "" || fieldValue === "." || fieldValue === "..") {
+      return toolError(`Invalid path parameter '${field.inputName}'.`)
+    }
+    url = url.replaceAll(`{${field.name}}`, fieldValue)
+  }
+  const unresolved = url.match(/\{[^{}]+\}/)
+  if (unresolved !== null) return toolError(`Unresolved path parameter ${unresolved[0]}.`)
+  return url
+}
+
+const serializeSimple = (
+  field: Plan["fields"][number],
+  value: unknown,
+  encode: (value: string) => string,
+): string | ToolError => {
+  const scalar = (item: unknown): string | ToolError =>
+    item !== null && typeof item !== "string" && typeof item !== "number" && typeof item !== "boolean"
+      ? toolError(`Parameter '${field.inputName}' contains an unsupported nested value.`)
+      : encode(String(item))
+  if (Array.isArray(value)) {
+    const items = value.map(scalar)
+    const invalid = items.find((item): item is ToolError => item instanceof ToolError)
+    return invalid ?? items.join(",")
+  }
+  if (!isRecord(value)) return scalar(value)
+  const entries = Object.entries(value).flatMap<string | ToolError>(([name, item]) => {
+    const rendered = scalar(item)
+    if (rendered instanceof ToolError) return [rendered]
+    return field.explode ? [`${encode(name)}=${rendered}`] : [encode(name), rendered]
+  })
+  const invalid = entries.find((item): item is ToolError => item instanceof ToolError)
+  return invalid ?? entries.join(",")
+}
+
+const serializeQuery = (
+  request: HttpClientRequest.HttpClientRequest,
+  field: Plan["fields"][number],
+  value: unknown,
+): HttpClientRequest.HttpClientRequest | ToolError => {
+  if (field.style === "deepObject") {
+    if (!isRecord(value)) return toolError(`Deep-object parameter '${field.inputName}' must be an object.`)
+    return Object.entries(value).reduce<HttpClientRequest.HttpClientRequest | ToolError>((current, [name, item]) => {
+      if (current instanceof ToolError) return current
+      if (item === undefined || (item !== null && typeof item === "object")) {
+        return toolError(`Deep-object parameter '${field.inputName}' contains an unsupported nested value.`)
+      }
+      return HttpClientRequest.appendUrlParam(current, `${field.name}[${name}]`, String(item))
+    }, request)
+  }
+  if (Array.isArray(value)) {
+    const rendered = serializeSimple(field, value, String)
+    if (rendered instanceof ToolError) return rendered
+    if (!field.explode) return HttpClientRequest.appendUrlParam(request, field.name, rendered)
+    if (value.some((item) => item === undefined || (item !== null && typeof item === "object"))) {
+      return toolError(`Query parameter '${field.inputName}' contains an unsupported nested value.`)
+    }
+    return value.reduce(
+      (current, item) => HttpClientRequest.appendUrlParam(current, field.name, String(item)),
+      request,
+    )
+  }
+  if (isRecord(value) && field.explode) {
+    return Object.entries(value).reduce<HttpClientRequest.HttpClientRequest | ToolError>((current, [name, item]) => {
+      if (current instanceof ToolError) return current
+      if (item === undefined || (item !== null && typeof item === "object")) {
+        return toolError(`Query parameter '${field.inputName}' contains an unsupported nested value.`)
+      }
+      return HttpClientRequest.appendUrlParam(current, name, String(item))
+    }, request)
+  }
+  const rendered = serializeSimple(field, value, String)
+  return rendered instanceof ToolError ? rendered : HttpClientRequest.appendUrlParam(request, field.name, rendered)
+}
+
+const readResponseBody = (response: HttpClientResponse.HttpClientResponse, plan: Plan): Effect.Effect<string, ToolError> =>
+  Effect.gen(function* () {
+    const contentLength = response.headers["content-length"]
+    const parsedSize = contentLength === undefined ? undefined : Number.parseInt(contentLength, 10)
+    const declaredSize = parsedSize !== undefined && Number.isSafeInteger(parsedSize) && parsedSize >= 0 ? parsedSize : undefined
+    if (declaredSize !== undefined && declaredSize > maxResponseBodyBytes) {
+      return yield* Effect.fail(toolError(`${plan.operation.method} ${plan.operation.path} response exceeds 50 MiB.`))
+    }
+    let body = Buffer.allocUnsafe(Math.min(maxResponseBodyBytes, declaredSize ?? 64 * 1024))
+    let size = 0
+    yield* Stream.runForEach(response.stream, (chunk) => {
+      if (size + chunk.byteLength > maxResponseBodyBytes) {
+        return Effect.fail(toolError(`${plan.operation.method} ${plan.operation.path} response exceeds 50 MiB.`))
+      }
+      if (size + chunk.byteLength > body.byteLength) {
+        const grown = Buffer.allocUnsafe(Math.min(maxResponseBodyBytes, Math.max(size + chunk.byteLength, body.byteLength * 2)))
+        body.copy(grown, 0, 0, size)
+        body = grown
+      }
+      body.set(chunk, size)
+      size += chunk.byteLength
+      return Effect.void
+    }).pipe(
+      Effect.catch((cause) => {
+        if (cause instanceof ToolError) return Effect.fail(cause)
+        if (cause.reason._tag === "EmptyBodyError") return Effect.void
+        return Effect.fail(
+          toolError(`${plan.operation.method} ${plan.operation.path} failed while reading the response body.`, cause),
+        )
+      }),
+    )
+    return new TextDecoder().decode(body.subarray(0, size))
+  })

packages/codemode/src/openapi/spec.ts

@@ -0,0 +1,507 @@
+import { fromSchemaOpenApi3_0, fromSchemaOpenApi3_1 } from "effect/JsonSchema"
+import type { JsonSchema } from "../tool.js"
+import { isBlockedMember } from "../tool-runtime.js"
+import type {
+  Body,
+  Document,
+  InputField,
+  OperationInput,
+  Parsed,
+  SecurityRequirement,
+  SecurityScheme,
+} from "./types.js"
+
+export const methods = new Set(["get", "put", "post", "delete", "options", "head", "patch", "trace"])
+const parameterLocations = ["path", "query", "header"] as const
+const ignoredHeaderParameters = new Set(["accept", "content-type", "authorization"])
+
+export const isRecord = (value: unknown): value is Record<string, unknown> =>
+  typeof value === "object" && value !== null && !Array.isArray(value)
+
+const asArray = (value: unknown): ReadonlyArray<unknown> => (Array.isArray(value) ? value : [])
+
+export const nonEmptyString = (value: unknown): string | undefined =>
+  typeof value === "string" && value !== "" ? value : undefined
+
+// Guards record lookups keyed by spec- or model-controlled names against
+// prototype-inherited values (e.g. a parameter named `toString`).
+export const own = <T>(record: Readonly<Record<string, T>>, key: string): T | undefined =>
+  Object.hasOwn(record, key) ? record[key] : undefined
+
+export const resolve = (document: Document, value: unknown): unknown => {
+  const next = (current: unknown, seen: ReadonlySet<string>): unknown => {
+    if (!isRecord(current)) return current
+    const ref = nonEmptyString(current.$ref)
+    if (ref === undefined || !ref.startsWith("#/") || seen.has(ref)) return current
+    const target = ref
+      .slice(2)
+      .split("/")
+      .map((segment) => segment.replaceAll("~1", "/").replaceAll("~0", "~"))
+      .reduce<unknown>((item, segment) => (isRecord(item) ? own(item, segment) : undefined), document)
+    return target === undefined ? current : next(target, new Set([...seen, ref]))
+  }
+  return next(value, new Set())
+}
+
+const projectSchema = (document: Document, value: unknown): JsonSchema => {
+  if (!isRecord(value)) return {}
+  const normalized = nonEmptyString(document.openapi)?.startsWith("3.0")
+    ? fromSchemaOpenApi3_0(value)
+    : fromSchemaOpenApi3_1(value)
+  return Object.keys(normalized.definitions).length === 0
+    ? normalized.schema
+    : { ...normalized.schema, $defs: normalized.definitions }
+}
+
+export const componentDefinitions = (document: Document): Readonly<Record<string, JsonSchema>> => {
+  const components = isRecord(document.components) ? document.components : {}
+  const schemas = isRecord(components.schemas) ? components.schemas : {}
+  return Object.fromEntries(Object.entries(schemas).map(([name, value]) => [name, projectSchema(document, value)]))
+}
+
+const withDefinitions = (schema: JsonSchema, definitions: Readonly<Record<string, JsonSchema>>): JsonSchema => {
+  if (Object.keys(definitions).length === 0) return schema
+  const local = isRecord(schema.$defs) ? schema.$defs : {}
+  return { ...schema, $defs: { ...definitions, ...local } }
+}
+
+const isJsonMediaType = (mediaType: string): boolean => {
+  const normalized = mediaType.split(";")[0]?.trim().toLowerCase() ?? ""
+  return normalized === "application/json" || normalized.endsWith("+json")
+}
+
+const isBinaryMediaType = (document: Document, mediaType: string, value: unknown): boolean => {
+  const normalized = mediaType.split(";")[0]?.trim().toLowerCase() ?? ""
+  if (!isJsonMediaType(normalized) && !normalized.startsWith("text/")) return true
+  if (!isRecord(value)) return false
+  const schema = resolve(document, value.schema)
+  return isRecord(schema) && schema.format === "binary"
+}
+
+const jsonContent = (content: Record<string, unknown>): { readonly mediaType: string; readonly schema: unknown } | undefined => {
+  const entry = Object.entries(content).find(([mediaType]) => isJsonMediaType(mediaType))
+  return entry !== undefined && isRecord(entry[1]) ? { mediaType: entry[0], schema: entry[1].schema } : undefined
+}
+
+const isFlattenableObjectBody = (
+  schema: unknown,
+  requestRequired: boolean,
+): schema is Record<string, unknown> & { readonly properties: Record<string, unknown> } =>
+  isRecord(schema) &&
+  requestRequired &&
+  schema.type === "object" &&
+  isRecord(schema.properties) &&
+  schema.additionalProperties === false &&
+  schema.nullable !== true &&
+  schema.allOf === undefined &&
+  schema.anyOf === undefined &&
+  schema.oneOf === undefined
+
+type PlannedField = Omit<InputField, "inputName">
+
+const operationParameters = (
+  document: Document,
+  pathItem: Record<string, unknown>,
+  operation: Record<string, unknown>,
+): Parsed<ReadonlyArray<PlannedField>> => {
+  // Operation-level parameters override path-level ones sharing (location, name).
+  const declared = new Map<
+    string,
+    { readonly name: string; readonly location: string; readonly parameter: Record<string, unknown> }
+  >()
+  for (const raw of [...asArray(pathItem.parameters), ...asArray(operation.parameters)]) {
+    const resolved = resolve(document, raw)
+    if (!isRecord(resolved)) return { ok: false, reason: "parameter declaration is invalid or unresolved" }
+    const name = nonEmptyString(resolved.name)
+    const location = nonEmptyString(resolved.in)
+    if (name === undefined || location === undefined)
+      return { ok: false, reason: "parameter declaration is missing name or location" }
+    declared.set(`${location}:${name}`, { name, location, parameter: resolved })
+  }
+  const unordered: Array<PlannedField> = []
+  for (const item of declared.values()) {
+    const name = item.name
+    const location = item.location
+    const resolved = item.parameter
+    if (location === "cookie") return { ok: false, reason: `cookie parameter '${name}' is not supported` }
+    if (location !== "path" && location !== "query" && location !== "header") {
+      return { ok: false, reason: `parameter '${name}' uses unsupported location '${location}'` }
+    }
+    if (location === "header" && ignoredHeaderParameters.has(name.toLowerCase())) continue
+    if (resolved.schema === undefined && resolved.content === undefined) {
+      return { ok: false, reason: `parameter '${name}' declares neither schema nor content` }
+    }
+    if (resolved.content !== undefined)
+      return { ok: false, reason: `parameter '${name}' uses unsupported content encoding` }
+    if (resolved.style !== undefined && nonEmptyString(resolved.style) === undefined) {
+      return { ok: false, reason: `parameter '${name}' has an invalid style` }
+    }
+    if (resolved.explode !== undefined && typeof resolved.explode !== "boolean") {
+      return { ok: false, reason: `parameter '${name}' has an invalid explode value` }
+    }
+    if (resolved.allowReserved !== undefined && typeof resolved.allowReserved !== "boolean") {
+      return { ok: false, reason: `parameter '${name}' has an invalid allowReserved value` }
+    }
+    if (resolved.allowReserved === true)
+      return { ok: false, reason: `parameter '${name}' uses unsupported allowReserved encoding` }
+    const declaredStyle = nonEmptyString(resolved.style) ?? (location === "query" ? "form" : "simple")
+    if (location === "query" && declaredStyle !== "form" && declaredStyle !== "deepObject") {
+      return { ok: false, reason: `query parameter '${name}' uses unsupported style '${declaredStyle}'` }
+    }
+    if (location !== "query" && declaredStyle !== "simple") {
+      return { ok: false, reason: `${location} parameter '${name}' uses unsupported style '${declaredStyle}'` }
+    }
+    const style = declaredStyle === "deepObject" ? "deepObject" : declaredStyle === "form" ? "form" : "simple"
+    const explode = typeof resolved.explode === "boolean" ? resolved.explode : style === "form"
+    if (style === "deepObject" && !explode) {
+      return { ok: false, reason: `query parameter '${name}' uses deepObject with explode=false` }
+    }
+    const base = projectSchema(document, resolved.schema)
+    const description = nonEmptyString(resolved.description)
+    unordered.push({
+      name,
+      location,
+      required: resolved.required === true || location === "path",
+      style,
+      explode,
+      schema: {
+        ...base,
+        ...(base.description === undefined && description !== undefined ? { description } : {}),
+      },
+    })
+  }
+  return {
+    ok: true,
+    value: parameterLocations.flatMap((location) => unordered.filter((field) => field.location === location)),
+  }
+}
+
+const operationBody = (
+  document: Document,
+  operation: Record<string, unknown>,
+): Parsed<{ readonly fields: ReadonlyArray<PlannedField>; readonly body: Body | undefined }> => {
+  const resolved = resolve(document, operation.requestBody)
+  if (!isRecord(resolved)) return { ok: true, value: { fields: [], body: undefined } }
+  const content = isRecord(resolved.content) ? resolved.content : {}
+  const selected = jsonContent(content)
+  if (selected === undefined) {
+    return {
+      ok: false,
+      reason: `request body has no JSON content (declared: ${Object.keys(content).join(", ") || "none"})`,
+    }
+  }
+  const schema = resolve(document, selected.schema)
+  const required = resolved.required === true
+  if (!isFlattenableObjectBody(schema, required)) {
+    return {
+      ok: true,
+      value: {
+        fields: [
+          {
+            name: "body",
+            location: "body",
+            required,
+            schema: projectSchema(document, selected.schema),
+            style: undefined,
+            explode: undefined,
+          },
+        ],
+        body: { required, mode: "value", mediaType: selected.mediaType },
+      },
+    }
+  }
+  const requiredProperties = new Set(
+    Array.isArray(schema.required) ? schema.required.filter((item): item is string => typeof item === "string") : [],
+  )
+  return {
+    ok: true,
+    value: {
+      fields: Object.entries(schema.properties).map(([name, value]) => ({
+        name,
+        location: "body" as const,
+        required: required && requiredProperties.has(name),
+        schema: projectSchema(document, value),
+        style: undefined,
+        explode: undefined,
+      })),
+      body: { required, mode: "object", mediaType: selected.mediaType },
+    },
+  }
+}
+
+export const operationInput = (
+  document: Document,
+  pathItem: Record<string, unknown>,
+  operation: Record<string, unknown>,
+): Parsed<OperationInput> => {
+  const parameters = operationParameters(document, pathItem, operation)
+  if (!parameters.ok) return parameters
+  const requestBody = operationBody(document, operation)
+  if (!requestBody.ok) return requestBody
+  const fields = [...parameters.value, ...requestBody.value.fields]
+
+  const conflicts = new Set(
+    [...Map.groupBy(fields, (field) => field.name)]
+      .filter(([, matches]) => new Set(matches.map((field) => field.location)).size > 1)
+      .map(([name]) => name),
+  )
+  const used = new Set<string>()
+  return {
+    ok: true,
+    value: {
+      fields: fields.map((field) => {
+        const visibleName = isBlockedMember(field.name) ? `${field.name}_2` : field.name
+        const base = conflicts.has(field.name) ? `${field.location}_${visibleName}` : visibleName
+        const next = (index: number): string => {
+          const candidate = index === 1 ? base : `${base}_${index}`
+          return used.has(candidate) ? next(index + 1) : candidate
+        }
+        const inputName = next(1)
+        used.add(inputName)
+        return { ...field, inputName }
+      }),
+      body: requestBody.value.body,
+    },
+  }
+}
+
+export const inputSchema = (
+  fields: ReadonlyArray<InputField>,
+  definitions: Readonly<Record<string, JsonSchema>>,
+): JsonSchema => {
+  const required = fields.filter((field) => field.required).map((field) => field.inputName)
+  return withDefinitions(
+    {
+      type: "object",
+      properties: Object.fromEntries(fields.map((field) => [field.inputName, field.schema])),
+      ...(required.length === 0 ? {} : { required }),
+    },
+    definitions,
+  )
+}
+
+const successfulResponses = (
+  document: Document,
+  operation: Record<string, unknown>,
+): Parsed<ReadonlyArray<Record<string, unknown>>> => {
+  if (!isRecord(operation.responses)) return { ok: true, value: [] }
+  const entries = Object.entries(operation.responses)
+  const selected = [
+    ...entries.filter(([status]) => /^2\d\d$/.test(status)).sort(([a], [b]) => a.localeCompare(b)),
+    ...entries.filter(([status]) => status.toUpperCase() === "2XX"),
+  ]
+  const responses: Array<Record<string, unknown>> = []
+  for (const [, value] of selected) {
+    const resolved = resolve(document, value)
+    if (!isRecord(resolved) || nonEmptyString(resolved.$ref) !== undefined) {
+      return { ok: false, reason: "successful response declaration is invalid or unresolved" }
+    }
+    responses.push(resolved)
+  }
+  return { ok: true, value: responses }
+}
+
+export const operationOutput = (
+  document: Document,
+  operation: Record<string, unknown>,
+  definitions: Readonly<Record<string, JsonSchema>>,
+): Parsed<JsonSchema | undefined> => {
+  if (operation["x-websocket"] === true) return { ok: false, reason: "WebSocket operations are not supported" }
+  const responses = successfulResponses(document, operation)
+  if (!responses.ok) return responses
+  const streams = responses.value.some(
+    (response) =>
+      isRecord(response.content) &&
+      Object.keys(response.content).some(
+        (mediaType) => mediaType.split(";")[0]?.trim().toLowerCase() === "text/event-stream",
+      ),
+  )
+  if (streams) return { ok: false, reason: "SSE operations are not supported" }
+  const binary = responses.value.some(
+    (response) =>
+      isRecord(response.content) &&
+      Object.entries(response.content).some(([mediaType, value]) => isBinaryMediaType(document, mediaType, value)),
+  )
+  if (binary) return { ok: false, reason: "binary responses are not supported" }
+
+  const outcomes: Array<JsonSchema> = []
+  for (const response of responses.value) {
+    if (response.content !== undefined && !isRecord(response.content)) return { ok: true, value: undefined }
+    const content = isRecord(response.content) ? response.content : {}
+    if (Object.keys(content).length === 0) {
+      outcomes.push({ type: "null" })
+      continue
+    }
+    for (const [mediaType, value] of Object.entries(content)) {
+      if (!isJsonMediaType(mediaType)) {
+        outcomes.push({ type: "string" })
+        continue
+      }
+      if (!isRecord(value) || value.schema === undefined) return { ok: true, value: undefined }
+      outcomes.push(projectSchema(document, value.schema))
+    }
+  }
+  if (outcomes.length === 0) return { ok: true, value: undefined }
+  return {
+    ok: true,
+    value: withDefinitions(outcomes.length === 1 ? outcomes[0] ?? {} : { anyOf: outcomes }, definitions),
+  }
+}
+
+const sanitizeOperationSegment = (raw: string): string => {
+  const base =
+    raw
+      .replaceAll(/[^A-Za-z0-9_$]+/g, "_")
+      .replace(/^_+|_+$/g, "")
+      .replace(/^([0-9])/, "_$1") || "operation"
+  return isBlockedMember(base) ? `${base}_2` : base
+}
+
+const fallbackOperationId = (method: string, path: string): string =>
+  [
+    method,
+    ...path
+      .split("/")
+      .filter((part) => part !== "")
+      .flatMap((part) => (part.startsWith("{") && part.endsWith("}") ? ["by", part.slice(1, -1)] : [part]))
+      .flatMap((part) => part.split(/[^A-Za-z0-9]+/).filter((word) => word !== "")),
+  ]
+    .map((word, index) => {
+      const lower = word.toLowerCase()
+      return index === 0 ? lower : `${lower.charAt(0).toUpperCase()}${lower.slice(1)}`
+    })
+    .join("")
+
+export const operationPath = (
+  method: string,
+  path: string,
+  operation: Record<string, unknown>,
+  used: ReadonlySet<string>,
+  namespaces: ReadonlySet<string>,
+): ReadonlyArray<string> => {
+  const raw = nonEmptyString(operation.operationId)
+  const segments = (raw === undefined ? [fallbackOperationId(method, path)] : raw.split(".")).map(sanitizeOperationSegment)
+  if (isOperationPathAvailable(segments, used, namespaces)) return segments
+  const conflict = segments.slice(0, -1).findIndex((_, index) => used.has(segments.slice(0, index + 1).join(".")))
+  if (conflict >= 0 && conflict + 1 < segments.length) {
+    const collapsed = segments.flatMap((segment, index) => {
+      if (index === conflict) {
+        const next = segments[index + 1] ?? ""
+        return [`${segment}${next.charAt(0).toUpperCase()}${next.slice(1)}`]
+      }
+      return index === conflict + 1 ? [] : [segment]
+    })
+    if (isOperationPathAvailable(collapsed, used, namespaces)) return collapsed
+  }
+  const fallback = segments.join("_")
+  const next = (index: number): string => {
+    const candidate = `${fallback}_${index}`
+    return isOperationPathAvailable([candidate], used, namespaces) ? candidate : next(index + 1)
+  }
+  return [next(2)]
+}
+
+const isOperationPathAvailable = (
+  segments: ReadonlyArray<string>,
+  used: ReadonlySet<string>,
+  namespaces: ReadonlySet<string>,
+): boolean => {
+  const key = segments.join(".")
+  if (used.has(key) || namespaces.has(key)) return false
+  return segments.slice(0, -1).every((_, index) => !used.has(segments.slice(0, index + 1).join(".")))
+}
+
+export const specServerUrl = (source: Record<string, unknown>): Parsed<string> => {
+  const server = asArray(source.servers).find(isRecord)
+  const url = server === undefined ? undefined : nonEmptyString(server.url)
+  if (url === undefined) return { ok: false, reason: "spec declares no servers; pass baseUrl" }
+  if (/\{[^{}]+\}/.test(url)) {
+    return { ok: false, reason: `server URL '${url}' is not an absolute URL; pass baseUrl` }
+  }
+  return validateBaseUrl(url)
+}
+
+export const validateBaseUrl = (value: string): Parsed<string> => {
+  if (!/^https?:\/\//i.test(value)) return { ok: false, reason: `server URL '${value}' is not an absolute HTTP(S) URL` }
+  const url = URL.parse(value)
+  if (url === null || (url.protocol !== "http:" && url.protocol !== "https:")) {
+    return { ok: false, reason: `server URL '${value}' is not an absolute HTTP(S) URL` }
+  }
+  if (url.search !== "" || url.hash !== "") {
+    return { ok: false, reason: `server URL '${value}' contains an unsupported query string or fragment` }
+  }
+  return { ok: true, value }
+}
+
+export const securityRequirements = (value: unknown): Parsed<ReadonlyArray<SecurityRequirement>> => {
+  if (value === undefined) return { ok: true, value: [] }
+  if (!Array.isArray(value)) return { ok: false, reason: "security declaration is not an array" }
+  const requirements: Array<SecurityRequirement> = []
+  for (const item of value) {
+    if (!isRecord(item)) return { ok: false, reason: "security requirement is not an object" }
+    const requirement = Object.create(null) as Record<string, ReadonlyArray<string>>
+    for (const [name, scopes] of Object.entries(item)) {
+      if (!Array.isArray(scopes)) return { ok: false, reason: "security requirement scopes are not string arrays" }
+      const parsed = scopes.filter((scope): scope is string => typeof scope === "string")
+      if (parsed.length !== scopes.length) {
+        return { ok: false, reason: "security requirement scopes are not string arrays" }
+      }
+      requirement[name] = parsed
+    }
+    requirements.push(requirement)
+  }
+  return { ok: true, value: requirements }
+}
+
+export const operationSecurityRequirements = (
+  value: unknown,
+  defaults: Parsed<ReadonlyArray<SecurityRequirement>>,
+  schemes: Readonly<Record<string, SecurityScheme>>,
+): Parsed<ReadonlyArray<SecurityRequirement>> => {
+  const parsed = value === undefined ? defaults : securityRequirements(value)
+  if (!parsed.ok) return parsed
+  const supported = parsed.value.filter((requirement) =>
+    Object.keys(requirement).every((name) => {
+      const scheme = own(schemes, name)
+      return scheme !== undefined && !(scheme.type === "apiKey" && scheme.in === "cookie")
+    }),
+  )
+  if (parsed.value.length === 0 || supported.length > 0) return { ok: true, value: supported }
+
+  const names = [...new Set(parsed.value.flatMap((requirement) => Object.keys(requirement)))]
+  const cookieScheme = names.find((name) => {
+    const definition = own(schemes, name)
+    return definition?.type === "apiKey" && definition.in === "cookie"
+  })
+  return {
+    ok: false,
+    reason:
+      cookieScheme === undefined
+        ? `security requirement references missing or malformed scheme: ${names.join(", ")}`
+        : `cookie authentication '${cookieScheme}' is not supported`,
+  }
+}
+
+export const securitySchemes = (document: Document): Readonly<Record<string, SecurityScheme>> => {
+  const components = isRecord(document.components) ? document.components : {}
+  const declared = isRecord(components.securitySchemes) ? components.securitySchemes : {}
+  return Object.fromEntries(
+    Object.entries(declared).flatMap<readonly [string, SecurityScheme]>(([name, value]) => {
+      const resolved = resolve(document, value)
+      if (!isRecord(resolved)) return []
+      const type = nonEmptyString(resolved.type)
+      if (type === "apiKey") {
+        const carrier = nonEmptyString(resolved.in)
+        const parameter = nonEmptyString(resolved.name)
+        if (parameter === undefined || (carrier !== "header" && carrier !== "query" && carrier !== "cookie")) return []
+        return [[name, { type, name: parameter, in: carrier }] as const]
+      }
+      if (type === "http") {
+        const scheme = nonEmptyString(resolved.scheme)?.toLowerCase()
+        return scheme === undefined ? [] : [[name, { type, scheme }] as const]
+      }
+      if (type === "oauth2" || type === "openIdConnect") return [[name, { type }] as const]
+      return []
+    }),
+  )
+}

packages/codemode/src/openapi/types.ts

@@ -0,0 +1,112 @@
+import { Effect } from "effect"
+import { HttpClient } from "effect/unstable/http"
+import type { Definition, JsonSchema } from "../tool.js"
+
+/** A parsed OpenAPI 3.x document. YAML must be parsed by the host. */
+export type Document = Record<string, unknown>
+
+/** The operation identity handed to auth resolution and errors. */
+export type Operation = {
+  readonly operationId: string | undefined
+  readonly method: string
+  readonly path: string
+  readonly summary: string | undefined
+  readonly description: string | undefined
+}
+
+/** A resolved OpenAPI security scheme from `components.securitySchemes`. */
+export type SecurityScheme =
+  | { readonly type: "apiKey"; readonly name: string; readonly in: "header" | "query" | "cookie" }
+  | { readonly type: "http"; readonly scheme: string }
+  | { readonly type: "oauth2" }
+  | { readonly type: "openIdConnect" }
+
+/**
+ * Credential material returned by a host auth resolver. The carrier for `apiKey`
+ * comes from the scheme definition, not the credential. `header` is the escape
+ * hatch for nonstandard schemes.
+ */
+export type Credential =
+  | { readonly type: "bearer"; readonly token: string }
+  | { readonly type: "basic"; readonly username: string; readonly password: string }
+  | { readonly type: "apiKey"; readonly value: string }
+  | { readonly type: "header"; readonly name: string; readonly value: string }
+
+/**
+ * Resolves credential material for one named security scheme at call time.
+ * `undefined` means unavailable, try the next OR alternative; a failure aborts
+ * the call rather than falling through.
+ */
+export type AuthResolver = (context: {
+  readonly name: string
+  readonly definition: SecurityScheme
+  readonly scopes: ReadonlyArray<string>
+  readonly operation: Operation
+}) => Effect.Effect<Credential | undefined, unknown>
+
+export type Options = {
+  readonly spec: Document
+  /** Overrides all document, path, and operation `servers`. Required when no applicable absolute server URL exists. */
+  readonly baseUrl?: string | undefined
+  /** Host credential resolution, keyed by security scheme name. */
+  readonly auth?: { readonly resolve: AuthResolver } | undefined
+  /** Static headers on every request. Not model-visible; declared header params may override them, auth always wins. */
+  readonly headers?: Readonly<Record<string, string>> | undefined
+}
+
+/** An operation that could not be represented as a tool, and why. */
+export type Skipped = {
+  readonly method: string
+  readonly path: string
+  readonly reason: string
+}
+
+export type Tools = { [name: string]: Definition<HttpClient.HttpClient> | Tools }
+
+export type Result = {
+  /** Tool subtree; the host places it under a key in its `tools` tree. */
+  readonly tools: Tools
+  readonly skipped: ReadonlyArray<Skipped>
+}
+
+export type Parsed<T> = { readonly ok: true; readonly value: T } | { readonly ok: false; readonly reason: string }
+
+export type InputLocation = "path" | "query" | "header" | "body"
+
+export type InputField = {
+  /** Model-visible field name after cross-location collision handling. */
+  readonly inputName: string
+  /** Original parameter or body-property name used on the wire. */
+  readonly name: string
+  readonly location: InputLocation
+  readonly required: boolean
+  readonly schema: JsonSchema
+  readonly style: "simple" | "form" | "deepObject" | undefined
+  readonly explode: boolean | undefined
+}
+
+export type Body = { readonly required: boolean; readonly mode: "object" | "value"; readonly mediaType: string }
+
+export type OperationInput = {
+  readonly fields: ReadonlyArray<InputField>
+  readonly body: Body | undefined
+}
+
+/** One OR alternative: scheme name -> required scopes. Empty object = unauthenticated is acceptable. */
+export type SecurityRequirement = Readonly<Record<string, ReadonlyArray<string>>>
+
+export type Plan = {
+  readonly operation: Operation
+  readonly url: string
+  readonly fields: ReadonlyArray<InputField>
+  readonly body: Body | undefined
+  readonly security: ReadonlyArray<SecurityRequirement>
+  readonly schemes: Readonly<Record<string, SecurityScheme>>
+  readonly auth: { readonly resolve: AuthResolver } | undefined
+  readonly headers: Readonly<Record<string, string>>
+}
+
+export type AppliedAuth = {
+  readonly headers: Readonly<Record<string, string>>
+  readonly query: Readonly<Record<string, string>>
+}