fix: handle production source failures and reduce ZIP work

src/core/source/github-content-miss.ts

@@ -0,0 +1,65 @@
+import { createHash } from "crypto";
+import AnonymousError from "../AnonymousError";
+import { ExpiringMap } from "../expiring-map";
+import { octokit, waitForTokenGate, RateLimitDelayError } from "../GitHubUtils";
+import { GitHubBaseData } from "./GitHubBase";
+
+type Miss = "file_not_found" | "repo_not_found" | "commit_not_found";
+const results = new ExpiringMap<Miss>(2048);
+const pending = new Map<string, Promise<Miss>>();
+
+function missKey(data: GitHubBaseData, token: string): string {
+  return createHash("sha256").update(JSON.stringify([
+    data.repoId, data.organization, data.repoName, data.commit, data.cacheGeneration, data.cacheRevision, token,
+  ])).digest("hex");
+}
+
+export function cachedContentMiss(data: GitHubBaseData, token: string): Miss | undefined {
+  return results.get(missKey(data, token));
+}
+
+/** A raw 404 can mean a missing file, lost repository access, or a removed revision. */
+export async function classifyContentMiss(data: GitHubBaseData, token: string): Promise<Miss> {
+  const key = missKey(data, token);
+  const cached = results.get(key);
+  if (cached) return cached;
+  const active = pending.get(key);
+  if (active) return active;
+  if (pending.size >= 64) throw new AnonymousError("cache_busy", { httpStatus: 503 });
+  const probe = (async (): Promise<Miss> => {
+    const oct = octokit(token);
+    const options = { owner: data.organization, repo: data.repoName, request: { timeout: 15_000 } };
+    try {
+      await waitForTokenGate(token);
+      await oct.repos.get(options);
+    } catch (error) {
+      if ((error as { status?: number }).status === 404) return "repo_not_found";
+      throw probeError(error);
+    }
+    try {
+      await waitForTokenGate(token);
+      // Only check that the revision resolves; do not download a potentially
+      // large commit diff just to classify a missing file.
+      await oct.repos.getCommit({ ...options, ref: data.commit || "HEAD", mediaType: { format: "sha" } });
+    } catch (error) {
+      const upstream = error as { status?: number; response?: { data?: { message?: string } } };
+      if (upstream.status === 404 || upstream.status === 409 || (upstream.status === 422 &&
+          /^No commit found for SHA\b/.test(upstream.response?.data?.message || ""))) return "commit_not_found";
+      throw probeError(error);
+    }
+    return "file_not_found";
+  })().then(result => { results.set(key, result, 30_000); return result; });
+  pending.set(key, probe);
+  try { return await probe; }
+  finally { if (pending.get(key) === probe) pending.delete(key); }
+}
+
+function probeError(error: unknown): AnonymousError {
+  if (error instanceof AnonymousError) return error;
+  if (error instanceof RateLimitDelayError) return new AnonymousError("github_rate_limit_exceeded", { httpStatus: 429, cause: error });
+  const status = (error as { status?: number }).status;
+  return new AnonymousError(status === 401 ? "token_expired" : status === 403 ? "repo_not_accessible" : "github_unavailable", {
+    httpStatus: status === 401 || status === 403 ? status : 502,
+    cause: error as Error,
+  });
+}