Use ruff select instead of extend-select to keep the rule set explicit

[albertvillanova]

This PR makes TRL's ruff lint rule set explicit and independent of ruff's own default rule selection.

Motivation

Ruff 0.16 raised its default rule selection from 59 to 413 rules. extend-select adds onto those defaults, so TRL silently inherits every rule ruff enables by default, including whole families the project never opted into (BLE, SIM, S, TRY, LOG, DTZ, PL*, PIE, FURB, RUF, PYI, ...).

This has two consequences today:

• A contributor whose editor or local install runs ruff 0.16.4 sees 272 errors that CI never reports, since CI pins 0.13.3.
• Any ruff bump past 0.16 breaks the quality job and rewrites source through --fix. This is why Bump https://github.com/astral-sh/ruff-pre-commit from v0.13.3 to 0.16.4 #6957 is red.

Solution

Use select, which replaces the default selection instead of extending it. The listed rule families stay exactly as they are, so the set of rules TRL enforces becomes a project decision rather than a function of the installed ruff version. Adopting any of the newly defaulted rules remains a separate, deliberate change.

At the pinned ruff 0.13.3 this is a no-op: both configurations resolve to byte-identical sets of 170 enabled rules, and ruff check on all tracked Python files reports All checks passed! before and after. It also passes under ruff 0.16.4 with this change applied.

Changes

• Replace extend-select with select in the ruff lint configuration
• Add a comment recording why the rule set is pinned explicitly

---

Note

Low Risk
Config-only change to lint tooling; no runtime or application logic is affected.

Overview
Ruff linting is pinned to an explicit rule list so newer Ruff releases cannot silently turn on hundreds of extra default rules.

In pyproject.toml, [tool.ruff.lint] now uses select (replacing extend-select) with the same families (E, F, I, W, UP, B, T, C). A short comment documents that this avoids inheriting Ruff 0.16+’s expanded defaults. Behavior at the pinned Ruff version should be unchanged; local/editor runs on newer Ruff should align with CI instead of surfacing rules the project never opted into.

^{Reviewed by Cursor Bugbot for commit 1324eb0. Bugbot is set up for automated code reviews on this repo. Configure here.}

[bot-ci-comment]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[albertvillanova]

Merging this PR as a fix of the CI to make it more solid.