Fix NaN handling in windowFileRead offset and limit

[pavankumar-vh]

Overview

Fix NaN handling in the windowFileRead function in common/src/util/file-read-limits.ts.

Bug Description

The function didn't validate that offset and limit are finite numbers. If they were NaN or Infinity, Math.floor(NaN ?? 1) would return NaN, causing Math.max(1, NaN) to return NaN.

Fix

Added Number.isFinite() checks to default to safe values for invalid numbers.

Testing

No existing tests for this function, but the fix prevents incorrect behavior with invalid inputs.

Files Changed

• common/src/util/file-read-limits.ts - Added NaN validation

Scope

This change only touches common/ which is an approved contribution area per the Contributing Guide.

[codebuff-team]

Good catch. Math.floor(offset ?? 1) only substitutes on null/undefined, so a NaN or Infinity value for offset or limit slips through, and Math.max(1, NaN) returns NaN, silently corrupting the read window. Your Number.isFinite() guard closes that gap correctly, and MAX_READ_FILE_LINES is a sensible fallback for limit.

A few things a maintainer will likely want before landing this:

• A small test case (e.g. windowFileRead(content, NaN, Infinity)) would be the difference between 'needs-work' and immediate merge — this file evidently has no coverage, and this is exactly the kind of fix that should ship with a regression test to stay fixed.
• Consider whether callers can actually produce NaN/Infinity here in practice (e.g. from bad JSON/tool-call args) — mentioning that in the PR body strengthens the case for the fix.

Scope and diff size are appropriate — this is a one-file, four-line change to common/, which is fair game per the contributing guide. Substance is right; just needs a test to be fully port-ready.