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ARCHIVED TRAINING / pallets/werkzeug

pallets__werkzeug-2535

This is a preserved training example. Membership in the current training wave has not been verified.
pallets/werkzeug · Task 116 of 169

Problem statement

path converter doesn't redirect to trailing slash
It seems to me that the automatic redirect for URLs with trailing shlashes (like `/user` → `/user/`) described in [Flask docs](https://flask.palletsprojects.com/en/2.2.x/quickstart/#unique-urls-redirection-behavior) and [Werkzeug docs](https://werkzeug.palletsprojects.com/en/2.2.x/routing/#rule-format) does not work if you use PathConverter in an URL definition.

I have this straightforward Flask application to reproduce the problem:
```
from flask import Flask, Response

app = Flask(__name__)

@app.route('/')
@app.route('/<path:username>/')
def main(username=None):
    return Response(f"It works! Hello, {username}")
```
In werkzeug 2.1.2, it works as expected and if you send a request to `/user`, it redirects you via HTTP/308 to `/user/`. The log is:
```
* Running on http://127.0.0.1:5000 (Press CTRL+C to quit)
127.0.0.1 - - [12/Oct/2022 14:47:37] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [12/Oct/2022 14:47:45] "GET /user HTTP/1.1" 308 -
127.0.0.1 - - [12/Oct/2022 14:47:45] "GET /user/ HTTP/1.1" 200 -
```
But when I use werkzeug 2.2.0, the same request gives me HTTP/404:
```
 * Running on http://127.0.0.1:5000 (Press CTRL+C to quit)
127.0.0.1 - - [12/Oct/2022 14:48:43] "GET /fooo HTTP/1.1" 404 -
```
I've tried a bisection of all the commits between those versions to see whether this was an intentional change or not and find that the difference has been introduced in: https://github.com/pallets/werkzeug/commit/5a7c0dec029d296a5e8131c8db51ce19e28c0c58

The workaround for this is to define both possible URLs for a single endpoint but it's not pretty. Also, the difference might cause problems if you still support Python 3.6 because pip installs older Flask and werkzeug for Python 3.6 where the redirect works fine and newer packages for Python 3.7+ where it does not.

Is this behavior intentional and if so, could you please add it to the documentation?

Training membership

opd_e4b_pure_v6a opd_e4b_pure_v6b opd_e4b_pure_v7 opd_e4b_pure_v7b opd_e4b_self_audit_v4

Task issues extracted from preserved verified_rft_messages training examples. This is not a verified current RL wave manifest.

Task and snapshot provenance

Snapshot captured 2026-11-12T17:06:59.476467+00:00 · Autoresearch-Arena/gemma-4-developer-agent

{
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    "opd_e4b_pure_v6a",
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  "examples": 11,
  "instance_id": "pallets__werkzeug-2535",
  "problem_statement": "path converter doesn't redirect to trailing slash\nIt seems to me that the automatic redirect for URLs with trailing shlashes (like `/user` → `/user/`) described in [Flask docs](https://flask.palletsprojects.com/en/2.2.x/quickstart/#unique-urls-redirection-behavior) and [Werkzeug docs](https://werkzeug.palletsprojects.com/en/2.2.x/routing/#rule-format) does not work if you use PathConverter in an URL definition.\r\n\r\nI have this straightforward Flask application to reproduce the problem:\r\n```\r\nfrom flask import Flask, Response\r\n\r\napp = Flask(__name__)\r\n\r\n@app.route('/')\r\n@app.route('/<path:username>/')\r\ndef main(username=None):\r\n    return Response(f\"It works! Hello, {username}\")\r\n```\r\nIn werkzeug 2.1.2, it works as expected and if you send a request to `/user`, it redirects you via HTTP/308 to `/user/`. The log is:\r\n```\r\n* Running on http://127.0.0.1:5000 (Press CTRL+C to quit)\r\n127.0.0.1 - - [12/Oct/2022 14:47:37] \"GET / HTTP/1.1\" 200 -\r\n127.0.0.1 - - [12/Oct/2022 14:47:45] \"GET /user HTTP/1.1\" 308 -\r\n127.0.0.1 - - [12/Oct/2022 14:47:45] \"GET /user/ HTTP/1.1\" 200 -\r\n```\r\nBut when I use werkzeug 2.2.0, the same request gives me HTTP/404:\r\n```\r\n * Running on http://127.0.0.1:5000 (Press CTRL+C to quit)\r\n127.0.0.1 - - [12/Oct/2022 14:48:43] \"GET /fooo HTTP/1.1\" 404 -\r\n```\r\nI've tried a bisection of all the commits between those versions to see whether this was an intentional change or not and find that the difference has been introduced in: https://github.com/pallets/werkzeug/commit/5a7c0dec029d296a5e8131c8db51ce19e28c0c58\r\n\r\nThe workaround for this is to define both possible URLs for a single endpoint but it's not pretty. Also, the difference might cause problems if you still support Python 3.6 because pip installs older Flask and werkzeug for Python 3.6 where the redirect works fine and newer packages for Python 3.7+ where it does not.\r\n\r\nIs this behavior intentional and if so, could you please add it to the documentation?",
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}
{
  "captured_at": "2026-11-12T17:06:59.476467+00:00",
  "membership": "archived training",
  "membership_evidence": "Task issues extracted from preserved verified_rft_messages training examples. This is not a verified current RL wave manifest.",
  "name": "Preserved post-training task archive",
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}