feat(core): add pluggable web search (#35558)

Co-authored-by: Dax Raad <d@ironbay.co>

packages/core/src/websearch.ts

@@ -0,0 +1,144 @@
+export * as WebSearch from "./websearch"
+
+import { WebSearch } from "@opencode-ai/schema/websearch"
+import { Context, Effect, Layer, Schema } from "effect"
+import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
+import { EventV2 } from "./event"
+import { KV } from "./kv"
+import { State } from "./state"
+
+export const ID = WebSearch.ID
+export type ID = WebSearch.ID
+
+export const Provider = WebSearch.Provider
+export type Provider = WebSearch.Provider
+
+export const Event = WebSearch.Event
+
+export const Input = WebSearch.Input
+export type Input = WebSearch.Input
+export type ProviderInput = WebSearch.ProviderInput
+
+export const Result = WebSearch.Result
+export type Result = WebSearch.Result
+
+export const Response = WebSearch.Response
+export type Response = WebSearch.Response
+
+export interface ProviderImplementation extends Provider {
+  readonly execute: (input: ProviderInput) => Effect.Effect<readonly Result[], unknown>
+}
+
+export class ProviderRequiredError extends Schema.TaggedErrorClass<ProviderRequiredError>()(
+  "WebSearch.ProviderRequired",
+  {},
+) {}
+
+export class ProviderNotFoundError extends Schema.TaggedErrorClass<ProviderNotFoundError>()(
+  "WebSearch.ProviderNotFound",
+  {
+    providerID: ID,
+  },
+) {}
+
+export class DisabledError extends Schema.TaggedErrorClass<DisabledError>()("WebSearch.Disabled", {}) {}
+
+export class RequestError extends Schema.TaggedErrorClass<RequestError>()("WebSearch.Request", {
+  providerID: ID,
+  cause: Schema.Defect(),
+}) {}
+
+export type Error = ProviderRequiredError | ProviderNotFoundError | DisabledError | RequestError
+
+export interface Interface extends State.Transformable<Draft> {
+  readonly providers: () => Effect.Effect<readonly Provider[]>
+  readonly default: () => Effect.Effect<Provider | undefined, DisabledError>
+  readonly query: (input: Input) => Effect.Effect<Response, Error>
+}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/v2/WebSearch") {}
+
+type Data = {
+  readonly providers: Map<ID, ProviderImplementation>
+  defaultProviderID?: ID
+}
+
+export type Draft = {
+  add: (provider: ProviderImplementation) => void
+  default: {
+    get: () => ID | undefined
+    set: (providerID: ID) => void
+  }
+}
+
+const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const events = yield* EventV2.Service
+    const kv = yield* KV.Service
+    const decodeResults = Schema.decodeUnknownEffect(Schema.Array(Result))
+    const state = State.create<Data, Draft>({
+      initial: () => ({ providers: new Map() }),
+      draft: (draft) => ({
+        add: (provider) => draft.providers.set(provider.id, provider),
+        default: {
+          get: () => draft.defaultProviderID,
+          set: (providerID) => (draft.defaultProviderID = providerID),
+        },
+      }),
+      finalize: () => events.publish(Event.Updated, {}).pipe(Effect.asVoid),
+    })
+
+    const requireProvider = (providers: Map<ID, ProviderImplementation>, providerID: ID) => {
+      const provider = providers.get(providerID)
+      return provider ? Effect.succeed(provider) : Effect.fail(new ProviderNotFoundError({ providerID }))
+    }
+
+    const defaultProvider = Effect.fn("WebSearch.default")(function* () {
+      const data = state.get()
+      const configured = data.defaultProviderID ? data.providers.get(data.defaultProviderID) : undefined
+      if (configured) return configured
+      const stored = yield* kv.get("websearch:provider")
+      if (stored === false) return yield* new DisabledError()
+      if (typeof stored !== "string") return
+      return data.providers.get(ID.make(stored))
+    })
+
+    const resolve = Effect.fn("WebSearch.resolve")(function* (input: Input) {
+      const providers = state.get().providers
+      if (input.providerID) return yield* requireProvider(providers, input.providerID)
+      const provider = yield* defaultProvider()
+      if (!provider) return yield* new ProviderRequiredError()
+      return provider
+    })
+
+    return Service.of({
+      transform: state.transform,
+      reload: state.reload,
+      providers: Effect.fn("WebSearch.providers")(function* () {
+        return Array.from(state.get().providers.values(), (provider) => ({
+          id: provider.id,
+          name: provider.name,
+        })).toSorted((a, b) => a.name.localeCompare(b.name))
+      }),
+      default: Effect.fn("WebSearch.defaultInfo")(function* () {
+        const provider = yield* defaultProvider()
+        return provider && { id: provider.id, name: provider.name }
+      }),
+      query: Effect.fn("WebSearch.query")(function* (input) {
+        const provider = yield* resolve(input)
+        const results = yield* provider.execute({ query: input.query }).pipe(
+          Effect.flatMap(decodeResults),
+          Effect.mapError((cause) => new RequestError({ providerID: provider.id, cause })),
+        )
+        return new Response({ providerID: provider.id, results })
+      }),
+    })
+  }),
+)
+
+export const node = makeLocationNode({
+  service: Service,
+  layer,
+  deps: [EventV2.node, KV.node],
+})