Add backward compatibility redirect for legacy episode URLsHEADlive

Maintain compatibility with old sequential integer episode URLs by
redirecting them to the new sqid-based URLs with a 301 permanent
redirect.

- Add /episode/{episode_id:int} route for legacy integer IDs - Redirect
with 301 status to indicate permanent move to new URL - Add test to
verify redirect behavior - Mark route as deprecated in documentation

This allows existing shared links to continue working while encouraging
adoption of the new non-sequential URLs. The legacy route can be
removed after a deprecation period.

Amp-Thread-ID:
https://ampcode.com/threads/T-cc5d29f0-454e-4864-8d7e-1ad69a42afa9
Co-authored-by: Amp <amp@ampcode.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/Biz/PodcastItLater/Web.py b/Biz/PodcastItLater/Web.py
index 12c45c4..1a94007 100644
--- a/Biz/PodcastItLater/Web.py
+++ b/Biz/PodcastItLater/Web.py
@@ -1284,6 +1284,23 @@ def rss_feed(request: Request, token: str) -> Response:  # noqa: ARG001
         return Response(f"Error generating feed: {e}", status_code=500)
 
 
+@app.get("/episode/{episode_id:int}")
+def episode_detail_legacy(
+    request: Request,  # noqa: ARG001
+    episode_id: int,
+) -> RedirectResponse:
+    """Redirect legacy integer episode IDs to sqid URLs.
+
+    Deprecated: This route exists for backward compatibility.
+    Will be removed in a future version.
+    """
+    episode_sqid = encode_episode_id(episode_id)
+    return RedirectResponse(
+        url=f"/episode/{episode_sqid}",
+        status_code=301,  # Permanent redirect
+    )
+
+
 @app.get("/episode/{episode_sqid}")
 def episode_detail(
     request: Request,
@@ -2124,6 +2141,19 @@ class TestEpisodeDetailPage(BaseWebTest):
         self.assertIn(f'href="/episode/{self.episode_sqid}"', response.text)
         self.assertIn("Test Episode", response.text)
 
+    def test_legacy_integer_id_redirects(self) -> None:
+        """Legacy integer episode IDs should redirect to sqid URLs."""
+        response = self.client.get(
+            f"/episode/{self.episode_id}",
+            follow_redirects=False,
+        )
+
+        self.assertEqual(response.status_code, 301)
+        self.assertEqual(
+            response.headers["location"],
+            f"/episode/{self.episode_sqid}",
+        )
+
 
 def test() -> None:
     """Run all tests for the web module."""