- Add HasUnsupportedUnicodePropertyEscape in internal/util to detect \p{...} / \P{...} escapes that fail Python re compilation.
- Strip incompatible pattern attributes during tool parameter normalization in codex/claude and openai/claude translators.
- Provide schema-aware fallback stripping in codex executor helps to protect downstream Codex requests without mutating non-schema user data.
- Export unified schema keyword lists in internal/util to eliminate duplication.
- Add comprehensive unit tests covering Artifact fixtures, lookaheads, and user data preservation.
Closes: #5644