feat(plugin): add session request hook

packages/plugin/src/v2/effect/README.md

@@ -92,6 +92,19 @@ yield *
   )
 ```
 
+The serialized provider request is also mutable before it is sent:
+
+```ts
+yield *
+  ctx.session.hook("request", (event) =>
+    Effect.sync(() => {
+      event.request = new Request(event.request, {
+        headers: new Headers([...event.request.headers, ["x-plugin", "enabled"]]),
+      })
+    }),
+  )
+```
+
 ## Reloading A Domain
 
 When data captured by a transform changes, reload the affected domain:

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

@@ -15,8 +15,14 @@ export interface SessionContext {
   tools: Record<string, { description: string; input: JsonSchema.JsonSchema }>
 }
 
+export interface SessionRequest {
+  readonly sessionID: Session.ID
+  request: Request
+}
+
 export interface SessionHooks {
   readonly context: SessionContext
+  readonly request: SessionRequest
 }
 
 export type SessionDomain = Pick<

packages/plugin/src/v2/promise/README.md

@@ -94,6 +94,16 @@ await ctx.session.hook("context", (event) => {
 })
 ```
 
+The serialized provider request is also mutable before it is sent:
+
+```ts
+await ctx.session.hook("request", (event) => {
+  event.request = new Request(event.request, {
+    headers: new Headers([...event.request.headers, ["x-plugin", "enabled"]]),
+  })
+})
+```
+
 Promise tools use plain object declarations with async executors:
 
 ```ts

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

@@ -15,8 +15,14 @@ export interface SessionContext {
   tools: Record<string, { description: string; input: JsonSchema.JsonSchema }>
 }
 
+export interface SessionRequest {
+  readonly sessionID: Session.ID
+  request: Request
+}
+
 export interface SessionHooks {
   readonly context: SessionContext
+  readonly request: SessionRequest
 }
 
 export type SessionDomain = Pick<SessionApi, "create" | "get" | "prompt" | "command" | "synthetic" | "interrupt"> & {