Two robustness fixes for the `_HAS_ANSWER_ARTIFACT` regex from the
parent commit, both caught by a thorough simulation suite covering
Linux/Mac/Windows line-ending portability and adversarial inputs.
1. **CRLF line endings.** The original `\n` literals missed Windows-
authored or CRLF-converted content (model echoing a pasted prompt,
etc.). Replaced with `\r?\n` everywhere a newline is required, so
closed code fences, numbered lists, and end-to-end re-prompt
decisions all work on `\r\n` as well as `\n`.
2. **Catastrophic backtracking on whitespace spam.** The numbered-list
alternative `(?:^|\r?\n)\s*\d+\.\s+\S.*?\r?\n\s*\d+\.` was
O(n^2) on long whitespace runs: `\s*` greedy + `\d+` failing +
`\s` matching `\r\n` led to repeated backtracking through the
newline characters. Measured at ~630ms for 10KB of `\r\n` repeats.
Fix: restrict the post-newline indent to `[ \t]*` (spaces / tabs
only). After `\r?\n` we are at column 0 and only spaces / tabs
are a sensible leading indent for a list item; greedy whitespace
was never needed. New worst case on the same input: <1ms (1000x
speedup).
Added 5 in-tree tests:
- test_artifact_regex_handles_crlf_code_fence
- test_artifact_regex_handles_crlf_numbered_list
- test_artifact_regex_handles_mixed_lf_crlf
- test_no_backtrack_on_crlf_spam (asserts <50ms on 10KB \r\n)
- test_no_reprompt_on_crlf_complete_python_game
All 18 reprompt-guard tests pass. All 253 llama_cpp-related tests pass.
Out-of-tree simulation suite (84 tests) passes on both Python 3.12 and
Python 3.13 inside isolated uv venvs.
2db8b81854