feat(plugin): add session request hook

packages/core/test/plugin-hooks.test.ts

@@ -4,6 +4,7 @@ import { Agent } from "@opencode-ai/schema/agent"
 import { Model } from "@opencode-ai/schema/model"
 import { Provider } from "@opencode-ai/schema/provider"
 import { Session } from "@opencode-ai/schema/session"
+import type { SessionHooks } from "@opencode-ai/plugin/v2/effect/session"
 import { Effect, Layer } from "effect"
 import { PluginHooks } from "../src/plugin/hooks"
 import { testEffect } from "./lib/effect"
@@ -28,7 +29,7 @@ describe("PluginHooks", () => {
           event.messages = [Message.user("changed")]
         }),
       )
-      const event = {
+      const event: SessionHooks["context"] = {
         sessionID: Session.ID.make("ses_hooks"),
         agent: Agent.ID.make("build"),
         model: Model.Ref.make({ providerID: Provider.ID.make("test"), id: Model.ID.make("model") }),
@@ -42,4 +43,34 @@ describe("PluginHooks", () => {
       expect(event.messages).toEqual([Message.user("changed")])
     }),
   )
+
+  it.effect("registers session request hooks and triggers them sequentially", () =>
+    Effect.gen(function* () {
+      const hooks = yield* PluginHooks.Service
+      yield* hooks.register("session", "request", (event) =>
+        Effect.sync(() => {
+          event.headers.authorization = "Bearer changed"
+          delete event.body.max_output_tokens
+          event.body.store = false
+        }),
+      )
+      yield* hooks.register("session", "request", (event) =>
+        Effect.sync(() => {
+          event.headers = { ...event.headers, "x-store": String(event.body.store) }
+          event.body = { input: event.body.input ?? [] }
+        }),
+      )
+      const event: SessionHooks["request"] = {
+        sessionID: Session.ID.make("ses_request_hooks"),
+        agent: Agent.ID.make("build"),
+        model: Model.Ref.make({ providerID: Provider.ID.make("test"), id: Model.ID.make("model") }),
+        headers: { authorization: "Bearer original" },
+        body: { input: ["hello"], max_output_tokens: 1024 },
+      }
+
+      expect(yield* hooks.trigger("session", "request", event)).toBe(event)
+      expect(event.headers).toEqual({ authorization: "Bearer changed", "x-store": "false" })
+      expect(event.body).toEqual({ input: ["hello"] })
+    }),
+  )
 })

packages/core/test/plugin/promise.test.ts

@@ -218,6 +218,37 @@ describe("fromPromise", () => {
     }),
   )
 
+  it.effect("forwards session request hooks", () =>
+    Effect.gen(function* () {
+      const plugin = yield* PluginV2.Service
+      const hooks = yield* PluginHooks.Service
+      const host = yield* PluginHost.make(plugin)
+      yield* PluginPromise.fromPromise(
+        Plugin.define({
+          id: "promise-session-request",
+          setup: async (ctx) => {
+            await ctx.session.hook("request", (event) => {
+              event.headers["x-plugin"] = "promise"
+              delete event.body.max_output_tokens
+            })
+          },
+        }),
+      ).effect(host)
+      const event: SessionHooks["request"] = {
+        sessionID: SessionV2.ID.make("ses_promise_session_request"),
+        agent: AgentV2.ID.make("build"),
+        model: Model.Ref.make({ providerID: Provider.ID.make("test"), id: Model.ID.make("model") }),
+        headers: {},
+        body: { max_output_tokens: 1024 },
+      }
+
+      yield* hooks.trigger("session", "request", event)
+
+      expect(event.headers).toEqual({ "x-plugin": "promise" })
+      expect(event.body).toEqual({})
+    }),
+  )
+
   it.effect("disposes a hook registration on request", () =>
     Effect.gen(function* () {
       const agents = yield* AgentV2.Service

packages/plugin/src/v2/effect/session.ts

@@ -4,8 +4,11 @@ import type { Agent } from "@opencode-ai/schema/agent"
 import type { Model } from "@opencode-ai/schema/model"
 import type { Session } from "@opencode-ai/schema/session"
 import type { JsonSchema } from "effect"
+import type { SessionRequest } from "../session.js"
 import type { Hooks } from "./registration.js"
 
+export type { RequestBody, RequestValue, SessionRequest } from "../session.js"
+
 export interface SessionContext {
   readonly sessionID: Session.ID
   readonly agent: Agent.ID
@@ -17,6 +20,7 @@ export interface SessionContext {
 
 export interface SessionHooks {
   readonly context: SessionContext
+  readonly request: SessionRequest
 }
 
 export type SessionDomain = Pick<

packages/plugin/src/v2/promise/session.ts

@@ -4,8 +4,11 @@ import type { Agent } from "@opencode-ai/schema/agent"
 import type { Model } from "@opencode-ai/schema/model"
 import type { Session } from "@opencode-ai/schema/session"
 import type { JsonSchema } from "effect"
+import type { SessionRequest } from "../session.js"
 import type { Hooks } from "./registration.js"
 
+export type { RequestBody, RequestValue, SessionRequest } from "../session.js"
+
 export interface SessionContext {
   readonly sessionID: Session.ID
   readonly agent: Agent.ID
@@ -17,6 +20,7 @@ export interface SessionContext {
 
 export interface SessionHooks {
   readonly context: SessionContext
+  readonly request: SessionRequest
 }
 
 export type SessionDomain = Pick<

packages/plugin/src/v2/session.ts

@@ -0,0 +1,21 @@
+import type { Agent } from "@opencode-ai/schema/agent"
+import type { Model } from "@opencode-ai/schema/model"
+import type { Session } from "@opencode-ai/schema/session"
+
+export type RequestValue =
+  | null
+  | boolean
+  | number
+  | string
+  | Array<RequestValue>
+  | { [key: string]: RequestValue }
+
+export type RequestBody = Record<string, RequestValue>
+
+export interface SessionRequest {
+  readonly sessionID: Session.ID
+  readonly agent: Agent.ID
+  readonly model: Model.Ref
+  headers: Record<string, string>
+  body: RequestBody
+}