Reject non-finite --min-age in cleanup-grid-sessions.py

[Eugene (OEvgeny)]

Fixes #

Changelog Entry

Not required, development only.

Description

Follow-up to #5880, from this review comment.

cleanup-grid-sessions.py --min-age uses type=float, so it accepts nan and inf. The old check only rejected negative values:

• --min-age nan passed, and because age < nan is always false, the script deleted every session with a known start time, including young sessions of other runs on a shared grid.
• --min-age inf (or 1e400) passed and kept every session, which is never what the caller wants.

The script now rejects any value that is not a finite number of seconds, zero or more, before it contacts the grid.

Specific Changes

• cleanup-grid-sessions.py: validate --min-age with math.isfinite() in addition to the negative check, with the error --min-age must be a finite number of seconds, zero or more

Verified against a fake grid status server on a local port (one 10-second-old session, one 1000-second-old session, one with unknown start time), logging every request:

• nan, NaN, inf, -inf, Infinity, 1e400, -1, -0.5: exit code 2 with the error, no HTTP request

• 0, 400, 400 --dry-run, --dry-run, and no option: same output and requests as before

• I have added tests and executed them locally

• I have updated CHANGELOG.md

• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

[Copilot]

🟢 Approval recommended

The focused validation change addresses the unsafe inputs, with reported verification confirming rejection before grid access and preserved valid behavior.

No open issues 🎉

What changed in this PR

Hardens the Selenium Grid cleanup script so invalid age thresholds cannot cause unintended session cleanup.

Changes:

• Rejects non-finite and negative --min-age values before contacting the grid.
• Provides a clearer validation error while preserving valid inputs and defaults.

File	Description
.github/​skills/​webchat-html-tests/​scripts/​cleanup-grid-sessions.py	Adds finite, nonnegative age validation using math.isfinite().

_{Review effort: Balanced}