Accept nested extensions/<name>/extension.mjs in external-plugin canvas checks

eng/external-plugin-intake.mjs

@@ -380,7 +380,92 @@ async function validateRemoteRepository(repo, { ref, sha }, errors, warnings, to
   }
 }
 
-async function validateCanvasPluginMetadata(plugin, errors, warnings, token) {
+function buildGitTreePath(repo, treeish, { recursive = false } = {}) {
+  const encodedRepo = encodeRepoPath(repo);
+  const query = recursive ? "?recursive=1" : "";
+  return `/repos/${encodedRepo}/git/trees/${encodeURIComponent(treeish)}${query}`;
+}
+
+function normalizeTreeish(locator) {
+  const value = String(locator ?? "").trim();
+  // The Git Trees API takes the tree-ish as a single path segment. A full "refs/tags/<tag>"
+  // ref would break that, so reduce it to the bare tag name; commit SHAs and simple tag
+  // names pass through unchanged.
+  return value.startsWith("refs/tags/") ? value.slice("refs/tags/".length) : value;
+}
+
+// Resolve the tree SHA of a directory by walking the path one level at a time. Each hop is a
+// non-recursive tree fetch of a single directory, so the work is bounded by the path depth and
+// is independent of the overall repository size — unlike a root recursive fetch, which a large
+// unrelated monorepo can push over the API's truncation limit and never validate.
+async function resolveDirectoryTreeSha(repo, treeish, segments, token) {
+  let currentTreeish = treeish;
+  for (const segment of segments) {
+    const response = await fetchGitHubJson(buildGitTreePath(repo, currentTreeish), token);
+    if (response.kind !== "found" || !Array.isArray(response.data?.tree)) {
+      return { status: "apiError" };
+    }
+    if (response.data.truncated) {
+      // A single directory level exceeded the response limit; presence is unverifiable.
+      return { status: "apiError" };
+    }
+
+    const match = response.data.tree.find((entry) => entry?.path === segment);
+    if (!match) {
+      return { status: "missing" };
+    }
+    if (match.type !== "tree") {
+      return { status: "notDirectory" };
+    }
+    currentTreeish = match.sha;
+  }
+
+  return { status: "found", treeSha: currentTreeish };
+}
+
+// Inspect the (recursively fetched) "extensions" subtree for the plugin's canvas extension
+// entry point. Paths are relative to "extensions/", so the flat form is "extension.mjs" and a
+// nested form is "<name>/extension.mjs". Scoping the recursive fetch to this subtree keeps the
+// lookup complete without depending on the size of the rest of the repository.
+function analyzeCanvasExtensionSubtree(subtreeEntries) {
+  let flatIsBlob = false;
+  let flatIsTree = false;
+  let nestedEntryPath = null;
+
+  for (const entry of subtreeEntries) {
+    const entryPath = entry?.path;
+    if (typeof entryPath !== "string") {
+      continue;
+    }
+
+    if (entryPath === "extension.mjs") {
+      if (entry.type === "blob") {
+        flatIsBlob = true;
+      } else if (entry.type === "tree") {
+        flatIsTree = true;
+      }
+      continue;
+    }
+
+    const segments = entryPath.split("/");
+    if (segments.length === 2 && segments[1] === "extension.mjs" && entry.type === "blob") {
+      nestedEntryPath = nestedEntryPath ?? `extensions/${entryPath}`;
+    }
+  }
+
+  if (flatIsBlob) {
+    return { status: "found", entryPath: "extensions/extension.mjs" };
+  }
+  if (nestedEntryPath) {
+    return { status: "found", entryPath: nestedEntryPath };
+  }
+  if (flatIsTree) {
+    return { status: "notFile" };
+  }
+  return { status: "notFound" };
+}
+
+export async function validateCanvasPluginMetadata(plugin, errors, warnings, token) {
   const repo = plugin?.source?.repo;
   const sha = plugin?.source?.sha;
   const ref = plugin?.source?.ref;
@@ -471,41 +556,51 @@ async function validateCanvasPluginMetadata(plugin, errors, warnings, token) {
     );
   }
 
-  const extensionContainerPath = joinRepoPath(pluginRoot, "extensions");
-  const extensionContainerResponse = await fetchGitHubFile(repo, extensionContainerPath, releaseLocator, token);
-  if (extensionContainerResponse.kind === "notFound") {
+  const unverifiableEntryPointWarning =
+    `submission: could not verify the canvas extension entry point in GitHub repository "${repo}" at ${releaseLocatorDescription}; a maintainer should re-run intake`;
+  const extensionsSegments = [...(pluginRoot ? pluginRoot.split("/") : []), "extensions"];
+  const extensionsTree = await resolveDirectoryTreeSha(
+    repo,
+    normalizeTreeish(releaseLocator),
+    extensionsSegments,
+    token,
+  );
+  if (extensionsTree.status === "apiError") {
+    warnings.push(unverifiableEntryPointWarning);
+  } else if (extensionsTree.status === "missing") {
     errors.push(
       `submission: plugins tagged with "canvas" must include an "extensions" directory at ${releaseLocatorDescription}`,
     );
-  } else if (extensionContainerResponse.kind === "apiError") {
-    warnings.push(
-      `submission: could not verify "extensions" directory in GitHub repository "${repo}" at ${releaseLocatorDescription}; a maintainer should re-run intake`,
-    );
-  } else if (
-    !(
-      extensionContainerResponse.data?.type === "dir"
-      || Array.isArray(extensionContainerResponse.data)
-    )
-  ) {
+  } else if (extensionsTree.status === "notDirectory") {
     errors.push(
       `submission: "extensions" must be a directory in ${releaseLocatorDescription}`,
     );
-  }
-
-  const extensionEntryPath = joinRepoPath(pluginRoot, "extensions", "extension.mjs");
-  const extensionEntryResponse = await fetchGitHubFile(repo, extensionEntryPath, releaseLocator, token);
-  if (extensionEntryResponse.kind === "notFound") {
-    errors.push(
-      `submission: plugins tagged with "canvas" must include "extensions/extension.mjs" at ${releaseLocatorDescription}`,
-    );
-  } else if (extensionEntryResponse.kind === "apiError") {
-    warnings.push(
-      `submission: could not verify "extensions/extension.mjs" in GitHub repository "${repo}" at ${releaseLocatorDescription}; a maintainer should re-run intake`,
-    );
-  } else if (extensionEntryResponse.data?.type !== "file") {
-    errors.push(
-      `submission: "extensions/extension.mjs" must be a file in ${releaseLocatorDescription}`,
+  } else {
+    const subtreeResponse = await fetchGitHubJson(
+      buildGitTreePath(repo, extensionsTree.treeSha, { recursive: true }),
+      token,
     );
+    if (subtreeResponse.kind !== "found" || !Array.isArray(subtreeResponse.data?.tree)) {
+      warnings.push(unverifiableEntryPointWarning);
+    } else {
+      const canvasStructure = analyzeCanvasExtensionSubtree(subtreeResponse.data.tree);
+      if (canvasStructure.status === "found") {
+        // Entry point located (flat or nested); nothing to report.
+      } else if (subtreeResponse.data.truncated) {
+        // Absence is only inconclusive if the (already extensions-scoped) subtree itself is
+        // truncated, which would take an implausibly large extensions directory; flag it as
+        // unverifiable rather than falsely rejecting.
+        warnings.push(unverifiableEntryPointWarning);
+      } else if (canvasStructure.status === "notFile") {
+        errors.push(
+          `submission: "extensions/extension.mjs" must be a file in ${releaseLocatorDescription}`,
+        );
+      } else {
+        errors.push(
+          `submission: plugins tagged with "canvas" must include a canvas extension entry point at "extensions/extension.mjs" or "extensions/<extension>/extension.mjs" at ${releaseLocatorDescription}`,
+        );
+      }
+    }
   }
 
   const previewPath = joinRepoPath(pluginRoot, EXTERNAL_CANVAS_PREVIEW_PATH);