feat(plugin): add session request hook (#35794)

packages/core/src/plugin/hooks.ts

@@ -0,0 +1,67 @@
+export * as PluginHooks from "./hooks"
+
+import type { AISDKHooks } from "@opencode-ai/plugin/v2/effect/aisdk"
+import type { SessionHooks } from "@opencode-ai/plugin/v2/effect/session"
+import type { ToolHooks } from "@opencode-ai/plugin/v2/effect/tool"
+import { Context, Effect, Layer, Scope } from "effect"
+import { makeLocationNode } from "../effect/app-node"
+import { State } from "../state"
+
+export interface Domains {
+  readonly aisdk: AISDKHooks
+  readonly session: SessionHooks
+  readonly tool: ToolHooks
+}
+
+type Callback<Event> = (event: Event) => Effect.Effect<void>
+
+export interface Interface {
+  readonly register: <Domain extends keyof Domains, Name extends keyof Domains[Domain]>(
+    domain: Domain,
+    name: Name,
+    callback: Callback<Domains[Domain][Name]>,
+  ) => Effect.Effect<State.Registration, never, Scope.Scope>
+  readonly trigger: <Domain extends keyof Domains, Name extends keyof Domains[Domain]>(
+    domain: Domain,
+    name: Name,
+    event: Domains[Domain][Name],
+  ) => Effect.Effect<Domains[Domain][Name]>
+}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/v2/PluginHooks") {}
+
+const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const callbacks = new Map<string, Function[]>()
+    const key = (domain: keyof Domains, name: PropertyKey) => `${domain}.${String(name)}`
+
+    const register: Interface["register"] = Effect.fn("PluginHooks.register")(function* (domain, name, callback) {
+      const scope = yield* Scope.Scope
+      const id = key(domain, name)
+      let active = true
+      callbacks.set(id, [...(callbacks.get(id) ?? []), callback])
+      const dispose = Effect.sync(() => {
+        if (!active) return
+        active = false
+        const next = (callbacks.get(id) ?? []).filter((item) => item !== callback)
+        if (next.length === 0) callbacks.delete(id)
+        else callbacks.set(id, next)
+      })
+      yield* Scope.addFinalizer(scope, dispose)
+      return { dispose }
+    })
+
+    const trigger: Interface["trigger"] = Effect.fn("PluginHooks.trigger")(function* (domain, name, event) {
+      for (const callback of callbacks.get(key(domain, name)) ?? []) {
+        const result: Effect.Effect<void> = Reflect.apply(callback, undefined, [event])
+        yield* result
+      }
+      return event
+    })
+
+    return Service.of({ register, trigger })
+  }),
+)
+
+export const node = makeLocationNode({ service: Service, layer, deps: [] })