Handle deleted PR branches in push-to-pull-request-branch with opt-in skip mode

.github/workflows/design-decision-gate.md

@@ -22,6 +22,7 @@ safe-outputs:
     allowed-files:
       - docs/adr/**
     patch-format: bundle
+    ignore-missing-branch-failure: true
     commit-title-suffix: " [design-decision-gate]"
   noop:
   messages:

actions/setup/js/push_to_pull_request_branch.cjs

@@ -24,6 +24,25 @@ const { getGitAuthEnv } = require("./git_helpers.cjs");
 
 /** @type {string} Safe output type handled by this module */
 const HANDLER_TYPE = "push_to_pull_request_branch";
+const MISSING_BRANCH_ERROR_TEMPLATE = branchName => `Branch ${branchName} no longer exists on origin (it may have been deleted), can't push to it.`;
+const MISSING_REMOTE_REF_PATTERNS = [
+  "couldn't find remote ref",
+  "could not find remote ref",
+  "remote ref does not exist",
+  "did not match any file(s) known to git",
+  "unknown revision or path not in the working tree",
+  "fatal: couldn't find remote ref",
+  "exit code 128",
+];
+
+/**
+ * @param {unknown} value
+ * @returns {boolean}
+ */
+function looksLikeMissingRemoteBranchError(value) {
+  const text = String(value ?? "").toLowerCase();
+  return MISSING_REMOTE_REF_PATTERNS.some(pattern => text.includes(pattern));
+}
 
 /**
  * Main handler factory for push_to_pull_request_branch
@@ -36,6 +55,7 @@ async function main(config = {}) {
   const titlePrefix = config.title_prefix || "";
   const envLabels = config.labels ? (Array.isArray(config.labels) ? config.labels : config.labels.split(",")).map(label => String(label).trim()).filter(label => label) : [];
   const ifNoChanges = config.if_no_changes || "warn";
+  const ignoreMissingBranchFailure = config.ignore_missing_branch_failure === true;
   const commitTitleSuffix = config.commit_title_suffix || "";
   const maxSizeKb = config.max_patch_size ? parseInt(String(config.max_patch_size), 10) : 1024;
   const maxCount = config.max || 0; // 0 means no limit
@@ -70,6 +90,7 @@ async function main(config = {}) {
     core.info(`Required labels: ${envLabels.join(", ")}`);
   }
   core.info(`If no changes: ${ifNoChanges}`);
+  core.info(`Ignore missing branch failure: ${ignoreMissingBranchFailure}`);
   if (commitTitleSuffix) {
     core.info(`Commit title suffix: ${commitTitleSuffix}`);
   }
@@ -464,9 +485,18 @@ async function main(config = {}) {
       });
 
       if (lsRemoteResult.exitCode === 2) {
+        const missingBranchError = MISSING_BRANCH_ERROR_TEMPLATE(branchName);
+        if (ignoreMissingBranchFailure) {
+          core.warning(`${missingBranchError} Skipping as configured by ignore-missing-branch-failure.`);
+          return {
+            success: false,
+            error: missingBranchError,
+            skipped: true,
+          };
+        }
         return {
           success: false,
-          error: `Branch ${branchName} no longer exists on origin (it may have been deleted), can't push to it.`,
+          error: missingBranchError,
         };
       }
 
@@ -488,13 +518,24 @@ async function main(config = {}) {
         env: { ...process.env, ...gitAuthEnv },
       });
     } catch (fetchError) {
+      const fetchErrorMessage = fetchError instanceof Error ? fetchError.message : String(fetchError);
+      if (ignoreMissingBranchFailure && looksLikeMissingRemoteBranchError(fetchErrorMessage)) {
+        const missingBranchError = MISSING_BRANCH_ERROR_TEMPLATE(branchName);
+        core.warning(`${missingBranchError} Skipping as configured by ignore-missing-branch-failure.`);
+        return { success: false, error: missingBranchError, skipped: true };
+      }
       return { success: false, error: `Failed to fetch branch ${branchName}: ${fetchError instanceof Error ? fetchError.message : String(fetchError)}` };
     }
 
     // Check if branch exists on origin
     try {
       await exec.exec(`git rev-parse --verify origin/${branchName}`);
     } catch (verifyError) {
+      const missingBranchError = MISSING_BRANCH_ERROR_TEMPLATE(branchName);
+      if (ignoreMissingBranchFailure) {
+        core.warning(`${missingBranchError} Skipping as configured by ignore-missing-branch-failure.`);
+        return { success: false, error: missingBranchError, skipped: true };
+      }
       return { success: false, error: `Branch ${branchName} does not exist on origin, can't push to it: ${verifyError instanceof Error ? verifyError.message : String(verifyError)}` };
     }
 

actions/setup/js/push_to_pull_request_branch.test.cjs

@@ -645,6 +645,22 @@ index 0000000..abc1234
       expect(mockExec.exec).not.toHaveBeenCalled();
     });
 
+    it("should skip deleted branch failure when ignore_missing_branch_failure is enabled", async () => {
+      const patchPath = createPatchFile();
+
+      mockExec.getExecOutput.mockResolvedValueOnce({ exitCode: 2, stdout: "", stderr: "fatal: couldn't find remote ref feature-branch" });
+
+      const module = await loadModule();
+      const handler = await module.main({ ignore_missing_branch_failure: true });
+      const result = await handler({ patch_path: patchPath }, {});
+
+      expect(result.success).toBe(false);
+      expect(result.skipped).toBe(true);
+      expect(result.error).toContain("no longer exists on origin");
+      expect(mockCore.warning).toHaveBeenCalledWith(expect.stringContaining("ignore-missing-branch-failure"));
+      expect(mockExec.exec).not.toHaveBeenCalled();
+    });
+
     it("should fail with diagnostic error when branch existence check fails for other reasons", async () => {
       const patchPath = createPatchFile();
 
@@ -689,6 +705,23 @@ index 0000000..abc1234
       expect(result.error).toContain("does not exist on origin");
     });
 
+    it("should skip rev-parse missing branch failure when ignore_missing_branch_failure is enabled", async () => {
+      const patchPath = createPatchFile();
+
+      // git fetch succeeds, but git rev-parse fails
+      mockExec.exec.mockResolvedValueOnce(0); // fetch
+      mockExec.exec.mockRejectedValueOnce(new Error("fatal: Needed a single revision"));
+
+      const module = await loadModule();
+      const handler = await module.main({ ignore_missing_branch_failure: true });
+      const result = await handler({ patch_path: patchPath }, {});
+
+      expect(result.success).toBe(false);
+      expect(result.skipped).toBe(true);
+      expect(result.error).toContain("no longer exists on origin");
+      expect(mockCore.warning).toHaveBeenCalledWith(expect.stringContaining("ignore-missing-branch-failure"));
+    });
+
     it("should handle git checkout failure", async () => {
       const patchPath = createPatchFile();
 

pkg/parser/schemas/main_workflow_schema.json

@@ -7074,6 +7074,11 @@
                   "enum": ["warn", "error", "ignore"],
                   "description": "Behavior when no changes to push: 'warn' (default - log warning but succeed), 'error' (fail the action), or 'ignore' (silent success)"
                 },
+                "ignore-missing-branch-failure": {
+                  "type": "boolean",
+                  "description": "When true, treat deleted/missing pull request branch errors as a skipped push instead of a hard failure. Useful when the PR branch may be deleted before safe outputs run.",
+                  "default": false
+                },
                 "commit-title-suffix": {
                   "type": "string",
                   "description": "Optional suffix to append to generated commit titles (e.g., ' [skip ci]' to prevent triggering CI on the commit)"

pkg/workflow/compiler_safe_outputs_handlers.go

@@ -411,6 +411,7 @@ var handlerRegistry = map[string]handlerBuilder{
 			AddIfNotEmpty("title_prefix", c.TitlePrefix).
 			AddStringSlice("labels", c.Labels).
 			AddIfNotEmpty("if_no_changes", c.IfNoChanges).
+			AddIfTrue("ignore_missing_branch_failure", c.IgnoreMissingBranchFailure).
 			AddIfNotEmpty("commit_title_suffix", c.CommitTitleSuffix).
 			AddDefault("max_patch_size", maxPatchSize).
 			AddIfNotEmpty("target-repo", c.TargetRepoSlug).