fix(server): pushing a branch whose remote branch was deleted publishes it again

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

@@ -3431,7 +3431,7 @@ it.layer(layerTest)("GitVcsDriver core integration", (it) => {
       }),
     );
 
-    it.effect("reports remote status on unborn HEAD without failing", () =>
+    it.effect("reports status on unborn HEAD without failing or dropping its upstream", () =>
       Effect.gen(function* () {
         const cwd = yield* makeTmpDir();
         const driver = yield* GitVcsDriver.GitVcsDriver;
@@ -3445,6 +3445,17 @@ it.layer(layerTest)("GitVcsDriver core integration", (it) => {
         assert.equal(status.hasUpstream, false);
         assert.equal(status.aheadCount, 0);
         assert.equal(status.behindCount, 0);
+
+        const seed = yield* makeTmpDir();
+        const remote = yield* makeTmpDir("git-remote-");
+        yield* initRepoWithCommit(seed);
+        yield* git(remote, ["init", "--bare"]);
+        yield* git(seed, ["push", remote, `HEAD:refs/heads/${initialBranch}`]);
+        yield* git(cwd, ["remote", "add", "origin", remote]);
+        yield* git(cwd, ["fetch", "origin"]);
+        yield* git(cwd, ["config", `branch.${initialBranch}.remote`, "origin"]);
+        yield* git(cwd, ["config", `branch.${initialBranch}.merge`, `refs/heads/${initialBranch}`]);
+        assert.equal((yield* driver.statusDetailsLocal(cwd)).hasUpstream, true);
       }),
     );
 
@@ -5668,7 +5679,7 @@ it.layer(layerTest)("GitVcsDriver core integration", (it) => {
       }),
     );
 
-    it.effect("pushes with upstream setup and skips when already up to date", () =>
+    it.effect("pushes, skips when up to date, and republishes a deleted upstream", () =>
       Effect.gen(function* () {
         const cwd = yield* makeTmpDir();
         const remote = yield* makeTmpDir("git-remote-");
@@ -5703,6 +5714,17 @@ it.layer(layerTest)("GitVcsDriver core integration", (it) => {
           status: "skipped_up_to_date",
           branch: "feature/push",
         });
+
+        yield* git(cwd, ["push", "origin", "--delete", "feature/push"]);
+        yield* writeTextFile(cwd, "followup.txt", "followup\n");
+        yield* git(cwd, ["add", "-A"]);
+        yield* (yield* GitVcsDriver.GitVcsDriver).commit(cwd, "Add followup", "");
+        const republished = yield* (yield* GitVcsDriver.GitVcsDriver).pushCurrentBranch(cwd, null);
+        assert.deepInclude(republished, { status: "pushed", branch: "feature/push" });
+        assert.equal(
+          yield* git(remote, ["--git-dir=.", "rev-parse", "refs/heads/feature/push"]),
+          yield* git(cwd, ["rev-parse", "HEAD"]),
+        );
       }),
     );
 

apps/server/src/vcs/GitVcsDriverCore.ts

@@ -2232,6 +2232,10 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
 
     let refName: string | null = null;
     let upstreamRef: string | null = null;
+    // Git omits branch.ab when the upstream ref is gone, e.g. deleted after its PR merged,
+    // and also for an unborn HEAD, which can still track a fetched upstream.
+    let upstreamRefExists = false;
+    let isUnbornHead = false;
     let aheadCount = 0;
     let behindCount = 0;
     let aheadOfDefaultCount = 0;
@@ -2242,6 +2246,10 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
     const statusRecords = statusStdout.split("\0");
     for (let index = 0; index < statusRecords.length; index++) {
       const line = statusRecords[index]!;
+      if (line === "# branch.oid (initial)") {
+        isUnbornHead = true;
+        continue;
+      }
       if (line.startsWith("# branch.head ")) {
         const value = line.slice("# branch.head ".length).trim();
         refName = value.startsWith("(") ? null : value;
@@ -2252,11 +2260,13 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
         upstreamRef = value.length > 0 ? value : null;
         continue;
       }
-      if (includeDivergence && line.startsWith("# branch.ab ")) {
-        const value = line.slice("# branch.ab ".length).trim();
-        const parsed = parseBranchAb(value);
-        aheadCount = parsed.ahead;
-        behindCount = parsed.behind;
+      if (line.startsWith("# branch.ab ")) {
+        upstreamRefExists = true;
+        if (includeDivergence) {
+          const parsed = parseBranchAb(line.slice("# branch.ab ".length).trim());
+          aheadCount = parsed.ahead;
+          behindCount = parsed.behind;
+        }
         continue;
       }
       if (line.length > 0 && !line.startsWith("#")) {
@@ -2275,6 +2285,8 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
       }
     }
 
+    if (!upstreamRefExists && !isUnbornHead) upstreamRef = null;
+
     const isDefaultBranch =
       refName !== null &&
       (refName === defaultBranch ||