fix(label): tolerate forbidden fork label writes

scripts/github-type-label.mjs

@@ -86,6 +86,9 @@ export async function applyTypeLabel({ apiUrl = "https://api.github.com", reposi
 
   if (!response.ok) {
     const text = await response.text();
+    if (isLabelWriteForbidden(response.status, text)) {
+      return { applied: false, reason: "label-write-forbidden" };
+    }
     throw new Error(`Failed to apply ${label} to #${number}: ${response.status} ${text}`);
   }
   return { applied: true };
@@ -154,6 +157,10 @@ function nextLink(linkHeader) {
   return "";
 }
 
+function isLabelWriteForbidden(status, text) {
+  return status === 403 && /resource not accessible by integration/i.test(text);
+}
+
 const entrypointUrl = process.argv[1] ? pathToFileURL(process.argv[1]).href : "";
 
 if (import.meta.url === entrypointUrl) {

test/unit/github-type-label.test.ts

@@ -107,6 +107,54 @@ describe("GitHub type label classifier", () => {
     ]);
   });
 
+  it("does not fail the workflow when GitHub forbids a fork PR label write", async () => {
+    const calls: string[] = [];
+    const result = await applyTypeLabel({
+      repository: "JSONbored/gittensory",
+      token: "token",
+      number: 263,
+      label: "feature",
+      fetchImpl: async (input, init) => {
+        const method = init?.method ?? "GET";
+        calls.push(`${method} ${input.toString()}`);
+        if (method === "GET") return Response.json([{ name: "size:S" }]);
+        if (method === "POST") {
+          return Response.json(
+            {
+              message: "Resource not accessible by integration",
+              documentation_url: "https://docs.github.com/rest/issues/labels#add-labels-to-an-issue",
+              status: "403",
+            },
+            { status: 403 },
+          );
+        }
+        return new Response("unexpected method", { status: 500 });
+      },
+    });
+
+    expect(result).toEqual({ applied: false, reason: "label-write-forbidden" });
+    expect(calls).toEqual([
+      "GET https://api.github.com/repos/JSONbored/gittensory/issues/263/labels?per_page=100",
+      "POST https://api.github.com/repos/JSONbored/gittensory/issues/263/labels",
+    ]);
+  });
+
+  it("still fails on unexpected label write errors", async () => {
+    await expect(
+      applyTypeLabel({
+        repository: "JSONbored/gittensory",
+        token: "token",
+        number: 42,
+        label: "feature",
+        fetchImpl: async (_input, init) => {
+          const method = init?.method ?? "GET";
+          if (method === "GET") return Response.json([{ name: "size:S" }]);
+          return new Response("server error", { status: 500 });
+        },
+      }),
+    ).rejects.toThrow("Failed to apply feature to #42: 500 server error");
+  });
+
   it("reads paginated current labels before deciding to post", async () => {
     const calls: string[] = [];
     const labels = await readCurrentLabels({