feat(source-control): omit agent credits from PR merge messages

apps/mobile/src/features/settings/SettingsServerControlsRouteScreen.tsx

@@ -50,6 +50,7 @@ const PAGE_PROJECT_KEYS: Record<SettingsPage, readonly ProjectScopedServerSettin
   "new-threads": ["defaultThreadEnvMode", "worktreeSubmodules", "defaultRuntimeMode"],
   "source-control": [
     "defaultAutoPull",
+    "removeAgentCreditsOnMerge",
     "newWorktreesStartFromOrigin",
     "branchNamingMode",
     "branchNamePrefix",
@@ -334,6 +335,16 @@ function ServerSettingsDetail(props: { readonly page: SettingsPage }) {
                     disabled={disabledFor("branchNamingMode")}
                     onChange={write}
                   />
+                  <SettingsSection title="Pull requests">
+                    <SettingsSwitchRow
+                      icon="arrow.triangle.merge"
+                      label="Remove agent credits when merging"
+                      subtitle="Remove recognized agent credits from GitHub merge and squash messages, keeping human co-authors. Includes auto-merge. Excludes merge queues, stack merges, and existing commits."
+                      value={uniform("removeAgentCreditsOnMerge")}
+                      disabled={disabledFor("removeAgentCreditsOnMerge")}
+                      onValueChange={(value) => write({ removeAgentCreditsOnMerge: value })}
+                    />
+                  </SettingsSection>
                   <SettingsSection title="Default branch">
                     <SettingsSwitchRow
                       icon="arrow.down.circle"

apps/server/src/pullRequest/GitHubPullRequestCli.test.ts

@@ -1831,6 +1831,170 @@ layer("GitHubPullRequestCli.layer", (it) => {
     }),
   );
 
+  it.effect.each(["merge", "enable-auto-merge"] as const)(
+    "removes agent credits from the proposed message for %s",
+    (action) =>
+      Effect.gen(function* () {
+        mockedExecute
+          .mockReturnValueOnce(
+            Effect.succeed(
+              output(
+                encodeJson({
+                  data: {
+                    repository: {
+                      pullRequest: {
+                        isMergeQueueEnabled: false,
+                        headRefOid: "abc123",
+                        viewerMergeBodyText:
+                          "Details\n\nCo-authored-by: Alice <alice@example.com>\nCo-authored-by: Claude <noreply@anthropic.com>",
+                      },
+                    },
+                  },
+                }),
+              ),
+            ),
+          )
+          .mockReturnValueOnce(Effect.succeed(output("")));
+        const cli = yield* GitHubPullRequestCli.GitHubPullRequestCli;
+        yield* cli.runPullRequestAction({
+          cwd: "/w",
+          repository: "acme/web",
+          host: "github.com",
+          number: 7,
+          action,
+          mergeMethod: "squash",
+          removeAgentCreditsOnMerge: true,
+        });
+        expect(callAt(0).args).toContain("method=SQUASH");
+        expect(callAt(1).args.slice(-2)).toEqual(["--body-file", "-"]);
+        expect(callAt(1).args).toContain("--match-head-commit");
+        expect(callAt(1).args).toContain("abc123");
+        expect(callAt(1).stdin).toBe("Details\n\nCo-authored-by: Alice <alice@example.com>");
+        expect(callAt(1).args.join(" ")).not.toContain("alice@example.com");
+      }),
+  );
+
+  it.effect.each([
+    {
+      description: "an unchanged message",
+      body: "Details\n\nCo-authored-by: Alice <alice@example.com>",
+      queued: false,
+    },
+    {
+      description: "a merge queue",
+      body: "Co-authored-by: Claude <noreply@anthropic.com>",
+      queued: true,
+    },
+  ] as const)("keeps GitHub's default message for $description", ({ body, queued }) =>
+    Effect.gen(function* () {
+      mockedExecute
+        .mockReturnValueOnce(
+          Effect.succeed(
+            output(
+              encodeJson({
+                data: {
+                  repository: {
+                    pullRequest: {
+                      isMergeQueueEnabled: queued,
+                      headRefOid: "abc123",
+                      viewerMergeBodyText: body,
+                    },
+                  },
+                },
+              }),
+            ),
+          ),
+        )
+        .mockReturnValueOnce(Effect.succeed(output("")));
+      const cli = yield* GitHubPullRequestCli.GitHubPullRequestCli;
+      yield* cli.runPullRequestAction({
+        cwd: "/w",
+        repository: "acme/web",
+        host: "github.com",
+        number: 7,
+        action: "merge",
+        removeAgentCreditsOnMerge: true,
+      });
+      expect(callAt(0).args).toContain("method=MERGE");
+      expect(callAt(1).args).not.toContain("--body-file");
+      expect(callAt(1).stdin).toBeUndefined();
+    }),
+  );
+
+  it.effect("passes an explicitly empty body when the proposed message only credits an agent", () =>
+    Effect.gen(function* () {
+      mockedExecute
+        .mockReturnValueOnce(
+          Effect.succeed(
+            output(
+              encodeJson({
+                data: {
+                  repository: {
+                    pullRequest: {
+                      isMergeQueueEnabled: false,
+                      headRefOid: "abc123",
+                      viewerMergeBodyText: "Co-authored-by: Claude <noreply@anthropic.com>",
+                    },
+                  },
+                },
+              }),
+            ),
+          ),
+        )
+        .mockReturnValueOnce(Effect.succeed(output("")));
+      const cli = yield* GitHubPullRequestCli.GitHubPullRequestCli;
+      yield* cli.runPullRequestAction({
+        cwd: "/w",
+        repository: "acme/web",
+        host: "github.com",
+        number: 7,
+        action: "merge",
+        removeAgentCreditsOnMerge: true,
+      });
+      expect(callAt(1).stdin).toBe("");
+      expect(callAt(1).args).toContain("--body-file");
+    }),
+  );
+
+  it.effect("does not fetch a message for rebase merges", () =>
+    Effect.gen(function* () {
+      mockedExecute.mockReturnValue(Effect.succeed(output("")));
+      const cli = yield* GitHubPullRequestCli.GitHubPullRequestCli;
+      yield* cli.runPullRequestAction({
+        cwd: "/w",
+        repository: "acme/web",
+        host: "github.com",
+        number: 7,
+        action: "merge",
+        mergeMethod: "rebase",
+        removeAgentCreditsOnMerge: true,
+      });
+      expect(mockedExecute).toHaveBeenCalledTimes(1);
+      expect(callAt(0).args).toContain("--rebase");
+    }),
+  );
+
+  it.effect("refuses to merge when the proposed message cannot be read", () =>
+    Effect.gen(function* () {
+      mockedExecute.mockReturnValue(
+        Effect.succeed(output('{"data":{"repository":{"pullRequest":null}}}')),
+      );
+      const cli = yield* GitHubPullRequestCli.GitHubPullRequestCli;
+      const result = yield* Effect.result(
+        cli.runPullRequestAction({
+          cwd: "/w",
+          repository: "acme/web",
+          host: "github.com",
+          number: 7,
+          action: "merge",
+          removeAgentCreditsOnMerge: true,
+        }),
+      );
+      expect(result._tag).toBe("Failure");
+      expect(mockedExecute).toHaveBeenCalledTimes(1);
+    }),
+  );
+
   it.effect("arms auto-merge with the same strategy a merge would have used", () =>
     Effect.gen(function* () {
       mockedExecute.mockReturnValue(Effect.succeed(output("")));

apps/server/src/pullRequest/GitHubPullRequestCli.ts

@@ -1,3 +1,4 @@
+import { removeAgentCredits } from "./mergeMessage.ts";
 import { makeChecksRevalidator } from "./gitHubConditionalChecks.ts";
 import { runGitHubStackAction, type GitHubStackActionError } from "./githubStackActions.ts";
 import * as Cause from "effect/Cause";
@@ -737,6 +738,7 @@ export class GitHubPullRequestCli extends Context.Service<
       readonly action: PullRequestAction;
       readonly stackNumber?: number;
       readonly expectedStackHeads?: ReadonlyArray<PullRequestStackHead>;
+      readonly removeAgentCreditsOnMerge?: boolean;
       readonly mergeMethod?: PullRequestMergeMethod;
       readonly updateMethod?: PullRequestUpdateMethod;
     }) => Effect.Effect<void, GitHubPullRequestCliError>;
@@ -1055,6 +1057,35 @@ function cursorVariable(cursor: string | null): readonly [string, string] {
   return cursor === null ? ["-F", "cursor=null"] : ["-f", `cursor=${cursor}`];
 }
 
+const MERGE_MESSAGE_GRAPHQL_QUERY = `
+query PullRequestMergeMessage($owner: String!, $name: String!, $number: Int!, $method: PullRequestMergeMethod!) {
+  repository(owner: $owner, name: $name) {
+    pullRequest(number: $number) {
+      isMergeQueueEnabled
+      headRefOid
+      viewerMergeBodyText(mergeType: $method)
+    }
+  }
+}`;
+
+const decodeMergeMessageResponse = Schema.decodeUnknownResult(
+  Schema.fromJsonString(
+    Schema.Struct({
+      data: Schema.Struct({
+        repository: Schema.Struct({
+          pullRequest: Schema.Struct({
+            isMergeQueueEnabled: Schema.Boolean,
+            headRefOid: Schema.String,
+            viewerMergeBodyText: Schema.String,
+          }),
+        }),
+      }),
+    }),
+  ),
+);
+const decodeMergeMessage = (raw: string) =>
+  Result.map(decodeMergeMessageResponse(raw), (response) => response.data.repository.pullRequest);
+
 function actionArgs(
   action: PullRequestAction,
   mergeMethod: PullRequestMergeMethod | undefined,
@@ -2653,12 +2684,52 @@ export const make = Effect.gen(function* () {
         input.mergeMethod,
         input.updateMethod,
       );
-      return github
-        .execute({
+      return Effect.gen(function* () {
+        let body: string | undefined;
+        let expectedHead: string | undefined;
+        if (
+          input.removeAgentCreditsOnMerge === true &&
+          (input.action === "merge" || input.action === "enable-auto-merge") &&
+          input.mergeMethod !== "rebase"
+        ) {
+          const { owner, name } = parseRepositorySelector(input.repository);
+          const message = yield* graphqlRead({
+            cwd: input.cwd,
+            host: input.host,
+            operation: "runPullRequestAction",
+            allowReserve: true,
+            query: MERGE_MESSAGE_GRAPHQL_QUERY,
+            variables: [
+              ["-f", `owner=${owner}`],
+              ["-f", `name=${name}`],
+              ["-F", `number=${input.number}`],
+              ["-f", `method=${input.mergeMethod === "squash" ? "SQUASH" : "MERGE"}`],
+            ],
+            decode: decodeMergeMessage,
+          });
+          // GitHub's merge queue chooses its own message and ignores custom text.
+          if (!message.isMergeQueueEnabled) {
+            const cleaned = removeAgentCredits(message.viewerMergeBodyText);
+            if (cleaned !== message.viewerMergeBodyText) {
+              body = cleaned;
+              expectedHead = message.headRefOid;
+            }
+          }
+        }
+        yield* github.execute({
           cwd: input.cwd,
-          args: ["pr", subcommand!, String(input.number), ...repositoryArgs(input), ...flags],
-        })
-        .pipe(Effect.asVoid);
+          args: [
+            "pr",
+            subcommand!,
+            String(input.number),
+            ...repositoryArgs(input),
+            ...flags,
+            ...(expectedHead === undefined ? [] : ["--match-head-commit", expectedHead]),
+            ...(body === undefined ? [] : ["--body-file", "-"]),
+          ],
+          ...(body === undefined ? {} : { stdin: body }),
+        });
+      });
     },
 
     commentOnPullRequest: (input) =>

apps/server/src/pullRequest/GitHubPullRequestProvider.ts

@@ -582,6 +582,7 @@ export const make = Effect.gen(function* () {
           host: input.host,
           number: input.number,
           action: input.action,
+          ...(input.removeAgentCreditsOnMerge === true ? { removeAgentCreditsOnMerge: true } : {}),
           ...(input.stackNumber === undefined ? {} : { stackNumber: input.stackNumber }),
           ...(input.expectedStackHeads === undefined
             ? {}

apps/server/src/pullRequest/PullRequestProvider.ts

@@ -543,6 +543,8 @@ export interface PullRequestProviderApi {
       readonly action: PullRequestAction;
       readonly stackNumber?: number;
       readonly expectedStackHeads?: ReadonlyArray<PullRequestStackHead>;
+      /** GitHub merge message cleanup; ignored by hosts without support. */
+      readonly removeAgentCreditsOnMerge?: boolean;
       /** Meaningful for `merge` and `enable-auto-merge`; absent takes the host's own default. */
       readonly mergeMethod?: PullRequestMergeMethod;
       /** Only meaningful for `update-branch`; absent takes the host's own default. */