Fix BuffBench terminal crashes with numeric env values

[yolandaycao]

BuffBench configs can contain numeric env values like PORT: 3003. The SDK calls .trim() when scrubbing credentials, so terminal commands crash before starting.

Convert env values to strings before passing them to the SDK. Verified that printenv PORT succeeds with credential scrubbing enabled.

[codebuff-team]

Good catch and a minimal, well-scoped fix. The root cause is clearly explained: BuffBench eval JSON configs can produce non-string env values (e.g. PORT: 3003) despite the TS type saying Record<string, string>, and the SDK's credential scrubber calls .trim() on env values, crashing on numbers/booleans. Coercing with String(value) in the runner before handing off to the SDK is a sensible place to guard, since the runner is the boundary where untrusted eval JSON enters typed code.

A couple of things worth double-checking before porting:

• Object.fromEntries on undefined env would throw, but you've guarded with options.env && first, so that's fine.
• No test was added. Given this is a one-line coercion with a clear bug report, that's a minor omission, but a small unit test on CodebuffRunner construction with a numeric env value would make this bulletproof and guard against regressions.
• Consider whether the fix belongs at the type level too (loosening or validating the eval JSON schema) so future callers get a compile-time nudge, but that's a nice-to-have, not a blocker.

Overall: correct, narrowly scoped, addresses a real crash with a believable repro. Worth porting.