diff --git a/actions/setup/js/workflow_metadata_helpers.cjs b/actions/setup/js/workflow_metadata_helpers.cjs
index 9942fdd9199..af519e90fd3 100644
--- a/actions/setup/js/workflow_metadata_helpers.cjs
+++ b/actions/setup/js/workflow_metadata_helpers.cjs
@@ -13,15 +13,10 @@
 function getWorkflowMetadata(owner, repo) {
   const workflowName = process.env.GH_AW_WORKFLOW_NAME || "Workflow";
   const workflowId = process.env.GH_AW_WORKFLOW_ID || "";
-  const runId = context.runId || 0;
+  const runId = context.runId ?? 0;
   const runUrl = buildWorkflowRunUrl({ runId, serverUrl: context.serverUrl }, { owner, repo });
 
-  return {
-    workflowName,
-    workflowId,
-    runId,
-    runUrl,
-  };
+  return { workflowName, workflowId, runId, runUrl };
 }
 
 /**
@@ -38,14 +33,14 @@ function getWorkflowMetadata(owner, repo) {
  */
 function buildWorkflowRunUrl(ctx, workflowRepo) {
   const server = ctx.serverUrl || process.env.GITHUB_SERVER_URL || "https://github.com";
-  let { owner, repo } = workflowRepo || {};
+  let { owner = "", repo = "" } = workflowRepo ?? {};
   if (!owner || !repo) {
     // When context is spread (e.g. `{...context}`), prototype getters like context.repo
     // are not included. Fall back to GITHUB_REPOSITORY for the workflow repo.
-    const parts = (process.env.GITHUB_REPOSITORY || "").split("/");
-    if (parts.length === 2 && parts[0] && parts[1]) {
-      owner = owner || parts[0];
-      repo = repo || parts[1];
+    const [envOwner = "", envRepo = ""] = (process.env.GITHUB_REPOSITORY || "").split("/");
+    if (envOwner && envRepo) {
+      owner = owner || envOwner;
+      repo = repo || envRepo;
     }
   }
   return `${server}/${owner}/${repo}/actions/runs/${ctx.runId}`;
diff --git a/actions/setup/js/workflow_metadata_helpers.test.cjs b/actions/setup/js/workflow_metadata_helpers.test.cjs
index 00240a7dbf1..bfd8ded72e9 100644
--- a/actions/setup/js/workflow_metadata_helpers.test.cjs
+++ b/actions/setup/js/workflow_metadata_helpers.test.cjs
@@ -115,6 +115,15 @@ describe("getWorkflowMetadata", () => {
 
     expect(metadata.runUrl).toBe("https://github.com/my-owner/my-repo/actions/runs/7");
   });
+
+  it("should use 0 as runId when context.runId is explicitly 0", () => {
+    global.context = { runId: 0, serverUrl: "https://github.com" };
+
+    const metadata = getWorkflowMetadata("owner", "repo");
+
+    expect(metadata.runId).toBe(0);
+    expect(metadata.runUrl).toBe("https://github.com/owner/repo/actions/runs/0");
+  });
 });
 
 describe("buildWorkflowRunUrl", () => {
@@ -200,4 +209,56 @@ describe("buildWorkflowRunUrl", () => {
       }
     }
   });
+
+  it("should use explicit owner but fall back GITHUB_REPOSITORY for missing repo", () => {
+    const originalEnv = process.env.GITHUB_REPOSITORY;
+    process.env.GITHUB_REPOSITORY = "env-owner/env-repo";
+    try {
+      const url = buildWorkflowRunUrl({ serverUrl: "https://github.com", runId: 5 }, { owner: "explicit-owner", repo: "" });
+      expect(url).toBe("https://github.com/explicit-owner/env-repo/actions/runs/5");
+    } finally {
+      if (originalEnv === undefined) {
+        delete process.env.GITHUB_REPOSITORY;
+      } else {
+        process.env.GITHUB_REPOSITORY = originalEnv;
+      }
+    }
+  });
+
+  it("should use explicit repo but fall back GITHUB_REPOSITORY for missing owner", () => {
+    const originalEnv = process.env.GITHUB_REPOSITORY;
+    process.env.GITHUB_REPOSITORY = "env-owner/env-repo";
+    try {
+      const url = buildWorkflowRunUrl({ serverUrl: "https://github.com", runId: 6 }, { owner: "", repo: "explicit-repo" });
+      expect(url).toBe("https://github.com/env-owner/explicit-repo/actions/runs/6");
+    } finally {
+      if (originalEnv === undefined) {
+        delete process.env.GITHUB_REPOSITORY;
+      } else {
+        process.env.GITHUB_REPOSITORY = originalEnv;
+      }
+    }
+  });
+
+  it("should not fall back to GITHUB_REPOSITORY when both owner and repo are set", () => {
+    const originalEnv = process.env.GITHUB_REPOSITORY;
+    process.env.GITHUB_REPOSITORY = "env-owner/env-repo";
+    try {
+      const url = buildWorkflowRunUrl({ serverUrl: "https://github.com", runId: 8 }, { owner: "wf-owner", repo: "wf-repo" });
+      expect(url).toBe("https://github.com/wf-owner/wf-repo/actions/runs/8");
+      expect(url).not.toContain("env-owner");
+      expect(url).not.toContain("env-repo");
+    } finally {
+      if (originalEnv === undefined) {
+        delete process.env.GITHUB_REPOSITORY;
+      } else {
+        process.env.GITHUB_REPOSITORY = originalEnv;
+      }
+    }
+  });
+
+  it("should use string runId in URL", () => {
+    const url = buildWorkflowRunUrl({ serverUrl: "https://github.com", runId: "run-abc123" }, { owner: "owner", repo: "repo" });
+    expect(url).toBe("https://github.com/owner/repo/actions/runs/run-abc123");
+  });
 });