fix: make runCommand maxBuffer explicit

[sylvesterkaczmarek]

Summary

Thanks for the detailed report in #744. This makes the intended buffering behaviour explicit instead of relying on an undefined option overriding Node's 1 MiB spawnSync default.

• use an explicit 256 MiB default for runCommand
• preserve smaller caller-provided maxBuffer values used by measurement gates
• add regressions for output above 1 MiB and for explicit bounded output

Validation

• npm test (93 passed)
• node --test tests/process.test.mjs (4 passed)
• npm run check-version
• git diff --check

Fixes #744

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-06T22:10:13.287169Z	912e98d	PR opened

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