fabro/checkpoint.json

{
  "timestamp": "2026-03-16T12:07:16.209911Z",
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  "context_values": {
    "thread.start.current_node": "setup",
    "current.preamble": "Goal: UsernameValidator allows trailing newline in usernames\nDescription\n\t\nASCIIUsernameValidator and UnicodeUsernameValidator use the regex \nr'^[\\w.@+-]+$'\nThe intent is to only allow alphanumeric characters as well as ., @, +, and -. However, a little known quirk of Python regexes is that $ will also match a trailing newline. Therefore, the user name validators will accept usernames which end with a newline. You can avoid this behavior by instead using \\A and \\Z to terminate regexes. For example, the validator regex could be changed to\nr'\\A[\\w.@+-]+\\Z'\nin order to reject usernames that end with a newline.\nI am not sure how to officially post a patch, but the required change is trivial - using the regex above in the two validators in contrib.auth.validators.\n\n\n## Completed stages\n- **setup**: fail\n  - Script: `git clone https://github.com/django/django.git . && git checkout d26b2424437dabeeca94d7900b37d2df4410da0c && python -m pip install -e .`\n  - Stdout:\n    ```\n    fatal: destination path '.' already exists and is not an empty directory.\n    ```\n  - Stderr: (empty)\n- **solve**: success\n  - Model: claude-opus-4-6, 5.1k tokens in / 1.8k out\n  - Files: /tmp/django-fix/django/contrib/auth/validators.py\n",
    "internal.retry_count.extract_patch": 1,
    "internal.fidelity": "compact",
    "command.output": "",
    "thread.setup.current_node": "solve",
    "response.solve": "The fix works correctly. Both validators now:\n- ✅ Accept valid usernames (e.g., `validuser`)\n- ✅ Reject usernames with trailing newlines (e.g., `validuser\\n`)\n\n**Summary of changes:** In `django/contrib/auth/validators.py`, changed the regex in both `ASCIIUsernameValidator` and `UnicodeUsernameValidator` from `r'^[\\w.@+-]+$'` to `r'\\A[\\w.@+-]+\\Z'`. \n\nThe issue was that Python's `$` in regex matches both end-of-string and just before a trailing newline, while `\\Z` matches only the absolute end of the string. Similarly, `\\A` is used instead of `^` for consistency (matching only the absolute start of the string).",
    "internal.thread_id": "solve",
    "current_node": "extract_patch",
    "failure_signature": "",
    "last_stage": "solve",
    "command.stderr": "",
    "last_response": "The fix works correctly. Both validators now:\n- ✅ Accept valid usernames (e.g., `validuser`)\n- ✅ Reject usernames with trailing newlines (e.g., `validuser\\n`)\n\n**Summary of changes:** In `django/c",
    "internal.retry_count.solve": 1,
    "graph.rankdir": "LR",
    "internal.node_visit_count": 1,
    "outcome": "success",
    "graph.goal": "UsernameValidator allows trailing newline in usernames\nDescription\n\t\nASCIIUsernameValidator and UnicodeUsernameValidator use the regex \nr'^[\\w.@+-]+$'\nThe intent is to only allow alphanumeric characters as well as ., @, +, and -. However, a little known quirk of Python regexes is that $ will also match a trailing newline. Therefore, the user name validators will accept usernames which end with a newline. You can avoid this behavior by instead using \\A and \\Z to terminate regexes. For example, the validator regex could be changed to\nr'\\A[\\w.@+-]+\\Z'\nin order to reject usernames that end with a newline.\nI am not sure how to officially post a patch, but the required change is trivial - using the regex above in the two validators in contrib.auth.validators.\n",
    "failure_class": "",
    "internal.retry_count.setup": 1,
    "internal.run_id": "01KKV8M223JTFVZ853MV9PGXVD",
    "internal.retry_count.start": 1,
    "thread.solve.current_node": "extract_patch"
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  "node_outcomes": {
    "setup": {
      "status": "fail",
      "context_updates": {
        "command.stderr": "",
        "command.output": "fatal: destination path '.' already exists and is not an empty directory.\n"
      },
      "failure": {
        "message": "Script failed with exit code: 128\n\n## stdout\nfatal: destination path '.' already exists and is not an empty directory.\n",
        "failure_class": "deterministic"
      },
      "duration_ms": 26
    },
    "extract_patch": {
      "status": "success",
      "context_updates": {
        "command.output": "",
        "command.stderr": ""
      },
      "notes": "Script completed: git diff",
      "duration_ms": 30
    },
    "start": {
      "status": "success",
      "duration_ms": 0
    },
    "solve": {
      "status": "success",
      "context_updates": {
        "response.solve": "The fix works correctly. Both validators now:\n- ✅ Accept valid usernames (e.g., `validuser`)\n- ✅ Reject usernames with trailing newlines (e.g., `validuser\\n`)\n\n**Summary of changes:** In `django/contrib/auth/validators.py`, changed the regex in both `ASCIIUsernameValidator` and `UnicodeUsernameValidator` from `r'^[\\w.@+-]+$'` to `r'\\A[\\w.@+-]+\\Z'`. \n\nThe issue was that Python's `$` in regex matches both end-of-string and just before a trailing newline, while `\\Z` matches only the absolute end of the string. Similarly, `\\A` is used instead of `^` for consistency (matching only the absolute start of the string).",
        "last_response": "The fix works correctly. Both validators now:\n- ✅ Accept valid usernames (e.g., `validuser`)\n- ✅ Reject usernames with trailing newlines (e.g., `validuser\\n`)\n\n**Summary of changes:** In `django/c",
        "last_stage": "solve"
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      "notes": "Stage completed: solve",
      "usage": {
        "model": "claude-opus-4-6",
        "input_tokens": 5085,
        "output_tokens": 1751,
        "cache_read_tokens": 58025,
        "cache_write_tokens": 10158,
        "reasoning_tokens": 21,
        "cost": 0.2076
      },
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        "/tmp/django-fix/django/contrib/auth/validators.py"
      ],
      "duration_ms": 57355
    }
  },
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    "setup|deterministic|script failed with exit code: <n> ## stdout fatal: destination path '.' already exists and is not an empty directory.": 1
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}