Python

First

Read local instructions, metadata, public APIs, callers, and relevant tests. Follow explicit repository requirements, not accidental nearby style. Ask about conflicting requirements before editing. Preserve configured tooling; use uv for new or unconfigured projects. Change only what the task requires.

Default decisions

Working pattern

This internal helper demonstrates a Result boundary, not a package export. Copy the contract, not its domain. Do not wrap a sufficient direct stdlib call.

from rust_ok import Err, Ok, Result


def parse_integer(raw: str, /, *, base: int = 10) -> Result[int, ValueError]:
    """Parse an integer, retaining expected conversion errors as values."""
    try:
        value = int(raw, base=base)
    except ValueError as error:
        return Err(error)
    return Ok(value)

Guardrails

• Handle or propagate every Result. Catch specific documented exceptions at the failing operation. Preserve error context; no bare unwrap, swallowed error, broad suppression, or success-shaped fallback. Programming defects remain visible, not ordinary failure values.
• Validate external input explicitly; annotations and removable assertions are not runtime validation. Use zip(strict=True) for equal lengths and unpacking for required cardinality. Do not revalidate trusted data everywhere.
• Keep meaningful types; do not hide uncertain contracts behind Any or casts. Use context managers for resources and readable loops over clever chains. Do not block an async event loop. Measure performance claims.
• Reuse public APIs and fixtures. No legacy compatibility wrappers, unrelated dependency churn, generated-file edits, logging wrappers, or print debugging.

Finish

Test public success, failures, and supported flag combinations. Reproduce bugs when practical. Run configured format, lint, type, and behavior checks, starting narrowly. Do not silence findings with blanket ignores, casts, or disabled rules. Pedantic sweeps are diagnostic, not automatic policy changes. Report results and gaps.

Read only when needed

• Public facades, domain contexts, flags, structured returns, or cross-package error translation: patterns.
• Public docstrings or array shape/dtype/axis contracts: docstrings.
• Requested strict sweep: inspect Ruff or ty; these use installed tools, not installers.

Do not preload references or evaluation files.