Implementing bot logic to close PRs with no changes

packages/mergebot/src/_tests/zero-edited-files.test.ts

@@ -0,0 +1,44 @@
+import { join } from "path";
+import { process } from "../compute-pr-actions";
+import { deriveStateForPR, PRQueryResponse } from "../pr-info";
+import { readJsonSync } from "../util/util";
+
+describe("zero edited files", () => {
+  it("closes open PRs immediately", async () => {
+    const responsePath = join(__dirname, "fixtures", "43136", "_response.json");
+    const response: PRQueryResponse = readJsonSync(responsePath);
+    const original = response.data.repository?.pullRequest;
+    if (!original) throw new Error("Missing pull request in fixture");
+
+    const prInfo = {
+      ...original,
+      changedFiles: 0,
+      files: { ...original.files, nodes: [] },
+    } as typeof original;
+
+    const derived = await deriveStateForPR(
+      prInfo,
+      async () => {
+        throw new Error("fetchFile should not be called");
+      },
+      async () => {
+        throw new Error("getDownloads should not be called");
+      },
+      new Date("2026-01-01T00:00:00.000Z"),
+    );
+
+    expect(derived).toMatchObject({
+      type: "remove",
+      message: "PR has no edited files",
+      shouldClose: true,
+    });
+
+    const actions = process(derived);
+    expect(actions).toMatchObject({
+      projectColumn: "*REMOVE*",
+      shouldClose: true,
+      shouldUpdateLabels: false,
+    });
+    expect(actions.responseComments).toEqual([]);
+  });
+});

packages/mergebot/src/compute-pr-actions.ts

@@ -284,6 +284,7 @@ export function process(prInfo: BotResult, extendedCallback: (info: ExtendedPrIn
     return {
       ...createEmptyActions(),
       projectColumn: prInfo.isDraft ? "Needs Author Action" : "*REMOVE*",
+      shouldClose: !!prInfo.shouldClose,
     };
   }
 

packages/mergebot/src/pr-info.ts

@@ -53,6 +53,7 @@ interface BotEnsureRemovedFromProject {
   readonly now: Date;
   readonly message: string;
   readonly isDraft: boolean;
+  readonly shouldClose?: boolean;
 }
 
 export interface PackageInfo {
@@ -216,6 +217,7 @@ export async function deriveStateForPR(
 
   if (prInfo.isDraft) return botEnsureRemovedFromProject("PR is a draft");
   if (prInfo.state !== "OPEN") return botEnsureRemovedFromProject("PR is not active");
+  if (prInfo.changedFiles === 0) return botEnsureRemovedFromProject("PR has no edited files", true);
 
   const headCommit = getHeadCommit(prInfo);
   // eslint-disable-next-line eqeqeq
@@ -316,8 +318,8 @@ export async function deriveStateForPR(
     return { type: "error", now, message, author: prInfo.author?.login };
   }
 
-  function botEnsureRemovedFromProject(message: string): BotEnsureRemovedFromProject {
-    return { type: "remove", now, message, isDraft: prInfo.isDraft };
+  function botEnsureRemovedFromProject(message: string, shouldClose = false): BotEnsureRemovedFromProject {
+    return { type: "remove", now, message, isDraft: prInfo.isDraft, shouldClose };
   }
 }