Link blobs to their history and back

Nothing in a commits payload says whether the path it lists is a file or
a directory: currentBlobPath, despite the name, is only the path filter,
and is set for a directory just the same. GitHub's own UI cannot tell
either, and points its browse button at /blob/<oid>/<path> so that the
redirect resolves a file to its blob. We do the same, and the blob route
already turns that redirect into one of our own tree URLs.

Breadcrumbs now stay in the view they were clicked from, so walking up
from a history lands in the history of each parent directory rather than
in its listing. The last crumb remains the page you are already on.

A path with no commits now says so rather than rendering an empty page.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01R7pRKdmTvNDgT4ZXrwkbH8

1 files changed, 33 insertions, 0 deletions

diff --git a/src/scraper.test.ts b/src/scraper.test.ts
index 2690f71..f6be2b6 100644
--- a/src/scraper.test.ts
+++ b/src/scraper.test.ts
@@ -195,6 +195,39 @@ describe("GitHub scraper", () => {
       assert.ok(data.commitGroups.length > 0);
     });
 
+    // GitHub serves a file's history from the same route as a directory's.
+    it("should fetch the history of a blob", async () => {
+      const data = await getGitHubCommits("actions", "deploy-pages", "main", "src/index.js");
+
+      assert.strictEqual(data.path, "src/index.js");
+
+      assert.ok(data.commitGroups.length > 0);
+      const commit = data.commitGroups[0].commits[0];
+      assert.strictEqual(commit.oid.length, 40);
+      assert.ok(commit.shortMessage.length > 0);
+    });
+
+    // What a history page's "Browse" link resolves to: the file as it stood at
+    // one of its commits. Nothing in a commits payload says whether the path is
+    // a file or a directory, so those links all point at the tree and rely on
+    // GitHub redirecting a file's to its blob.
+    it("should redirect a blob browsed at a commit to its blob view", async () => {
+      const oid = "b39c421b98f49d83ae50ec502c3ddfc3bf28f2c6";
+
+      await assert.rejects(getGitHubTree("actions", "deploy-pages", oid, "src/index.js"), (err) => {
+        assert(err instanceof RedirectError, "error should be a RedirectError");
+        assert.strictEqual(err.location, `/actions/deploy-pages/blob/${oid}/src/index.js`);
+        return true;
+      });
+
+      const data = await getGitHubBlob("actions", "deploy-pages", oid, "src/index.js");
+
+      assert.strictEqual(data.branch, oid);
+      assert.strictEqual(data.path, "src/index.js");
+      assert.strictEqual(data.size, "1.37 KB / 51 lines / 40 loc");
+      assert.strictEqual(data.textLines?.length, 51);
+    });
+
     it("should fetch releases", async () => {
       const data = await getGitHubReleases("actions", "deploy-pages");