feat(server): link_pull_request asks a subagent to end with its PR report

apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts

@@ -32,7 +32,7 @@ import * as McpToolAccess from "../../McpToolAccess.ts";
 import * as McpToolAccessTestkit from "../../McpToolAccess.testkit.ts";
 import { listThreadPullRequests } from "./handlers.ts";
 import * as PullRequestsHandlers from "./handlers.ts";
-import { PullRequestsToolkit } from "./tools.ts";
+import { CHILD_PULL_REQUEST_REPORT_NEXT, PullRequestsToolkit } from "./tools.ts";
 
 const PROJECT_ID = ProjectId.make("project-1");
 const THREAD_ID = ThreadId.make("thread-1");
@@ -353,6 +353,25 @@ describe("pull request toolkit handlers", () => {
     }),
   );
 
+  it.effect("asks a subagent thread to end with its PR report after it links", () =>
+    Effect.gen(function* () {
+      const harness = yield* makeHarness({
+        thread: {
+          ...makeThread([]),
+          lineage: {
+            rootThreadId: ThreadId.make("parent"),
+            parentThreadId: ThreadId.make("parent"),
+            relationshipToParent: "subagent",
+          },
+        },
+      });
+      const result = yield* harness.call("link_pull_request", {
+        url: "https://github.com/t3tools/t3code/pull/124",
+      });
+      expect(result).toMatchObject({ number: 124, next: CHILD_PULL_REQUEST_REPORT_NEXT });
+    }),
+  );
+
   it.effect("canonicalizes GitCafe links independently of the thread's project host", () =>
     Effect.gen(function* () {
       for (const host of ["git.cafe", "staging.git.cafe"]) {

apps/server/src/mcp/toolkits/pullRequests/handlers.ts

@@ -46,6 +46,7 @@ import {
   PullRequestProjectNotFoundError,
   PullRequestsToolkit,
   type ThreadPullRequestEntry,
+  CHILD_PULL_REQUEST_REPORT_NEXT,
 } from "./tools.ts";
 
 interface ResolvedTarget {
@@ -361,13 +362,17 @@ const make = Effect.gen(function* () {
     link_pull_request: writesThread((input) =>
       Effect.gen(function* () {
         const thread = yield* requireThread(PullRequestLinkFailedError, input.threadId);
+        const next =
+          thread.lineage.relationshipToParent === "subagent"
+            ? { next: CHILD_PULL_REQUEST_REPORT_NEXT }
+            : {};
         const project = yield* projectOf(thread, PullRequestLinkFailedError);
         const target = yield* resolveTarget(input, project);
         const existing = threadPullRequestsOf(thread).find((link) =>
           threadPullRequestKeysEqual(link, target),
         );
         if (existing && existing.source !== "stack-dismissed")
-          return { ...target, alreadyLinked: true };
+          return { ...target, alreadyLinked: true, ...next };
         const alreadyLinked = yield* engine
           .dispatch({
             type: "thread.pull-request.link",
@@ -384,7 +389,7 @@ const make = Effect.gen(function* () {
 
             Effect.catchCause(dispatchFailure(PullRequestLinkFailedError)),
           );
-        return { ...target, alreadyLinked };
+        return { ...target, alreadyLinked, ...next };
       }),
     ),
     unlink_pull_request: writesThread((input) =>

apps/server/src/mcp/toolkits/pullRequests/tools.ts

@@ -210,9 +210,14 @@ const PullRequestIdentity = {
   url: Schema.String,
 };
 
+/** A delegated child's report is how its parent learns the PR, so the link result asks for it. */
+export const CHILD_PULL_REQUEST_REPORT_NEXT =
+  "End your reply with: PR <full URL>, head <SHA>, checks and reviews <state>.";
+
 export const LinkPullRequestResult = Schema.Struct({
   ...PullRequestIdentity,
   alreadyLinked: Schema.Boolean,
+  next: Schema.optional(Schema.String),
 });
 export type LinkPullRequestResult = typeof LinkPullRequestResult.Type;