From 129cdb09b5b8ea72d9494c9895baae75aa832bbb Mon Sep 17 00:00:00 2001
From: Theo Browne <me@theo.li>
Date: Sun, 25 Oct 2026 16:59:38 -0700
Subject: [PATCH] feat(server): link_pull_request asks a subagent to end with
 its PR report

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../toolkits/pullRequests/handlers.test.ts    | 21 ++++++++++++++++++-
 .../src/mcp/toolkits/pullRequests/handlers.ts |  9 ++++++--
 .../src/mcp/toolkits/pullRequests/tools.ts    |  5 +++++
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts b/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts
index 507381531ac4..88691423c0ef 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts
+++ b/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"]) {
diff --git a/apps/server/src/mcp/toolkits/pullRequests/handlers.ts b/apps/server/src/mcp/toolkits/pullRequests/handlers.ts
index ca37361d244c..a4cd07b89fb4 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/handlers.ts
+++ b/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) =>
diff --git a/apps/server/src/mcp/toolkits/pullRequests/tools.ts b/apps/server/src/mcp/toolkits/pullRequests/tools.ts
index 878fd6c3702c..ef314b863ede 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/tools.ts
+++ b/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;