fix(server): background git status fetches no longer fill the disk with failed repacks (#13812)

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: t3dotgg

apps/server/src/vcs/GitVcsDriverCore.test.ts

@@ -1918,6 +1918,35 @@ it.layer(TestLayer)("GitVcsDriver core integration", (it) => {
       }),
     );
 
+    it.effect("does not start Git auto-maintenance from background upstream fetches", () =>
+      Effect.gen(function* () {
+        const cwd = yield* makeTmpDir();
+        const remote = yield* makeTmpDir("git-vcs-driver-remote-");
+        const { initialBranch } = yield* initRepoWithCommit(cwd);
+        yield* git(remote, ["init", "--bare"]);
+        yield* git(cwd, ["remote", "add", "origin", remote]);
+        yield* git(cwd, ["push", "-u", "origin", initialBranch]);
+        yield* git(cwd, ["repack", "-d"]);
+        yield* writeTextFile(cwd, "second.txt", "second\n");
+        yield* git(cwd, ["add", "second.txt"]);
+        yield* git(cwd, ["commit", "-m", "second commit"]);
+        yield* git(cwd, ["push"]);
+        yield* git(cwd, ["repack", "-d"]);
+        // Two packs make `git gc --auto` due, and without detaching it would run inside the fetch.
+        yield* git(cwd, ["config", "gc.autoPackLimit", "1"]);
+        yield* git(cwd, ["config", "gc.autoDetach", "false"]);
+        yield* git(cwd, ["config", "maintenance.autoDetach", "false"]);
+        const packCount = git(cwd, ["count-objects", "-v"]).pipe(
+          Effect.map((stdout) => stdout.match(/^packs: (\d+)$/m)?.[1]),
+        );
+        assert.equal(yield* packCount, "2");
+
+        yield* (yield* GitVcsDriver.GitVcsDriver).statusDetailsRemote(cwd);
+
+        assert.equal(yield* packCount, "2");
+      }),
+    );
+
     it.effect("uses origin HEAD for default-branch detection with a non-origin upstream", () =>
       Effect.gen(function* () {
         const cwd = yield* makeTmpDir();

apps/server/src/vcs/GitVcsDriverCore.ts

@@ -1127,10 +1127,14 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
   ): Effect.Effect<void, GitCommandError> => {
     const fetchCwd =
       path.basename(gitCommonDir) === ".git" ? path.dirname(gitCommonDir) : gitCommonDir;
+    // `--no-auto-gc` (a synonym of `--no-auto-maintenance` that older Git also knows) keeps
+    // this poll from starting `git gc --auto`. When that gc fails, for example on a repository
+    // with missing objects, Git retries it on every fetch and leaves a full-size `tmp_pack_*`
+    // behind each time, so a background poll could fill the disk.
     return executeGit(
       "GitVcsDriver.fetchRemoteForStatus",
       fetchCwd,
-      ["--git-dir", gitCommonDir, "fetch", "--quiet", "--no-tags", remoteName],
+      ["--git-dir", gitCommonDir, "fetch", "--quiet", "--no-tags", "--no-auto-gc", remoteName],
       {
         env: STATUS_UPSTREAM_REFRESH_ENV,
         fallbackErrorDetail: "Background Git fetch exited with a non-zero status.",