fix(core): shape compaction and generate requests with built-in context hooks (#48749)

packages/core/src/tool/plugin/opencode.ts

@@ -2,6 +2,7 @@ export * as OpenCodeTools from "./opencode.js"
 
 import { SystemPart, ToolFailure } from "@opencode/ai"
 import type { Context } from "@opencode/plugin/effect/plugin"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import { AbsolutePath } from "@opencode/schema/schema"
 import { Session } from "@opencode/schema/session"
 import { Effect, Schema } from "effect"
@@ -25,15 +26,17 @@ const MoveOutput = Schema.Struct({ sessionID: Session.ID, directory: AbsolutePat
 export const Plugin = {
   id: "opencode.tools",
   effect: Effect.fn("OpenCodeTools.Plugin")(function* (ctx: Context) {
-    yield* ctx.session.hook("context", (event) =>
+    const hook = (event: SessionHooks["context"]) =>
       Effect.sync(() => {
         event.system.push(
           SystemPart.make(
             "When you create a worktree outside the current working directory and intend to use it as your primary working directory, consider using `execute` to call `tools.opencode.session_move` and make the worktree the session's working directory.",
           ),
         )
-      }),
-    )
+      })
+    yield* ctx.session.hook("context", hook)
+    yield* ctx.session.hook("compaction", hook)
+    yield* ctx.session.hook("generate", hook)
     yield* ctx.tool
       .transform((draft) => {
         draft.namespace({ name: "opencode", description: "OpenCode session and runtime tools." })

packages/core/src/tool/plugin/patch.ts

@@ -1,6 +1,7 @@
 export * as PatchTool from "./patch.js"
 
 import type { Context } from "@opencode/plugin/effect/plugin"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import { ToolFailure } from "@opencode/ai"
 import { FileDiff } from "@opencode/schema/file-diff"
 import { Effect, Result, Schema } from "effect"
@@ -292,7 +293,7 @@ export const Plugin = {
       )
       .pipe(Effect.orDie)
 
-    yield* ctx.session.hook("context", (event) =>
+    const hook = (event: SessionHooks["context"]) =>
       Effect.sync(() => {
         const usePatch =
           event.model.id.includes("gpt-") && !event.model.id.includes("oss") && !event.model.id.includes("gpt-4")
@@ -302,8 +303,10 @@ export const Plugin = {
           return
         }
         delete event.tools.patch
-      }),
-    )
+      })
+    yield* ctx.session.hook("context", hook)
+    yield* ctx.session.hook("compaction", hook)
+    yield* ctx.session.hook("generate", hook)
   }),
 }
 

packages/core/src/tool/plugin/shell.ts

@@ -2,6 +2,7 @@ export * as ShellTool from "./shell.js"
 
 import { ToolFailure } from "@opencode/ai"
 import type { Context } from "@opencode/plugin/effect/plugin"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import type { ShellCreateBefore } from "@opencode/plugin/effect/shell"
 import type { Tool } from "@opencode/schema/tool"
 import { Deferred, Effect, Schema, Scope } from "effect"
@@ -271,12 +272,14 @@ export const Plugin = {
       )
       .pipe(Effect.orDie)
 
-    yield* ctx.session.hook("context", (event) =>
+    const hook = (event: SessionHooks["context"]) =>
       Effect.gen(function* () {
         const tool = event.tools[name]
         if (!tool) return
         tool.description = description(ShellSelect.name(yield* compatibleShell))
-      }),
-    )
+      })
+    yield* ctx.session.hook("context", hook)
+    yield* ctx.session.hook("compaction", hook)
+    yield* ctx.session.hook("generate", hook)
   }),
 }

packages/core/src/tool/plugin/subagent.ts

@@ -2,6 +2,7 @@ export * as SubagentTool from "./subagent.js"
 
 import { ToolFailure } from "@opencode/ai"
 import type { Context } from "@opencode/plugin/effect/plugin"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import { Effect, Schema } from "effect"
 import { Agent } from "../../agent.js"
 import { Config } from "../../config.js"
@@ -234,7 +235,7 @@ export const Plugin = {
       )
       .pipe(Effect.orDie)
 
-    yield* ctx.session.hook("context", (event) =>
+    const hook = (event: SessionHooks["context"]) =>
       Effect.gen(function* () {
         const tool = event.tools[name]
         if (!tool) return
@@ -258,7 +259,9 @@ export const Plugin = {
               `- ${agent.id}: ${agent.description ?? "This subagent should only be called when explicitly requested."}`,
           ),
         ].join("\n")
-      }),
-    )
+      })
+    yield* ctx.session.hook("context", hook)
+    yield* ctx.session.hook("compaction", hook)
+    yield* ctx.session.hook("generate", hook)
   }),
 }

packages/core/src/tool/plugin/websearch.ts

@@ -1,6 +1,7 @@
 export * as WebSearchTool from "./websearch.js"
 
 import type { Context } from "@opencode/plugin/effect/plugin"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import { ToolFailure } from "@opencode/ai"
 import { Effect, Schema, Semaphore } from "effect"
 import { HttpClientError } from "effect/unstable/http"
@@ -180,14 +181,16 @@ export const Plugin = {
       )
       .pipe(Effect.orDie)
 
-    yield* ctx.session.hook("context", (event) =>
+    const hook = (event: SessionHooks["context"]) =>
       Effect.gen(function* () {
         const disabled = yield* websearch.default().pipe(
           Effect.as(false),
           Effect.catchTag("WebSearch.Disabled", () => Effect.succeed(true)),
         )
         if (disabled) delete event.tools[name]
-      }),
-    )
+      })
+    yield* ctx.session.hook("context", hook)
+    yield* ctx.session.hook("compaction", hook)
+    yield* ctx.session.hook("generate", hook)
   }),
 }

packages/core/test/lib/tool.ts

@@ -66,7 +66,8 @@ export const registerToolPlugin = <R>(
     const context = host({
       ...overrides,
       session: {
-        hook: () => Effect.succeed({ dispose: Effect.void }),
+        ...overrides.session,
+        hook: overrides.session?.hook ?? (() => Effect.succeed({ dispose: Effect.void })),
       },
       tool: {
         transform: tools.transform,

packages/core/test/tool-patch.test.ts

@@ -9,11 +9,14 @@ import { Formatter } from "@opencode/core/formatter"
 import { FileMutation } from "@opencode/core/file-mutation"
 import { Location } from "@opencode/core/location"
 import { FileAccess } from "@opencode/core/file-access"
+import { Model } from "@opencode/core/model"
 import { Permission } from "@opencode/core/permission"
+import { Provider } from "@opencode/core/provider"
 import { AbsolutePath } from "@opencode/core/schema"
 import { Session } from "@opencode/core/session"
 import { Tool } from "@opencode/core/tool"
 import { PatchTool } from "@opencode/core/tool/plugin/patch"
+import type { SessionHooks } from "@opencode/plugin/effect/session"
 import { transformEnvironmentFiles } from "./fixture/environment"
 import { location } from "./fixture/location"
 import { tmpdir } from "./fixture/tmpdir"
@@ -22,9 +25,20 @@ import { testEffect } from "./lib/effect"
 import { permissionLayer } from "./lib/permission"
 import { toolIdentity, executeTool, registerToolPlugin, toolDefinitions } from "./lib/tool"
 
+const sessionHooks = new Map<string, (event: SessionHooks["context"]) => Effect.Effect<void>>()
 const patchToolNode = makeLocationNode({
   name: "test/patch-tool-plugin",
-  layer: Layer.effectDiscard(registerToolPlugin(PatchTool.Plugin)),
+  layer: Layer.effectDiscard(
+    registerToolPlugin(PatchTool.Plugin, {
+      session: {
+        hook: (name, callback) =>
+          Effect.sync(() => {
+            sessionHooks.set(name, callback as (event: SessionHooks["context"]) => Effect.Effect<void>)
+            return { dispose: Effect.void }
+          }),
+      },
+    }),
+  ),
   deps: [
     Tool.node,
     FileAccess.node,
@@ -153,6 +167,34 @@ const withTempTool = <A, E, R>(body: (directory: string, registry: Tool.Interfac
   )
 
 describe("PatchTool", () => {
+  it.live("selects the same edit tools for compaction and generate requests as the agent loop", () =>
+    withTempTool(() =>
+      Effect.gen(function* () {
+        const event = (id: string): SessionHooks["context"] => ({
+          sessionID,
+          agent: toolIdentity.agent,
+          model: Model.Ref.make({ providerID: Provider.ID.make("test"), id: Model.ID.make(id) }),
+          system: [],
+          messages: [],
+          tools: Object.fromEntries(
+            ["patch", "edit", "write", "read"].map((name) => [name, { description: name, input: { type: "object" } }]),
+          ),
+          options: {},
+        })
+        for (const name of ["context", "compaction", "generate"]) {
+          const hook = sessionHooks.get(name)
+          expect(hook).toBeDefined()
+          const claude = event("claude-sonnet-4")
+          yield* hook!(claude)
+          expect(Object.keys(claude.tools)).toEqual(["edit", "write", "read"])
+          const gpt = event("gpt-5")
+          yield* hook!(gpt)
+          expect(Object.keys(gpt.tools)).toEqual(["patch", "read"])
+        }
+      }),
+    ),
+  )
+
   it.live("registers and sequentially applies add, update, and delete hunks", () =>
     Effect.acquireUseRelease(
       Effect.promise(() => tmpdir()),