Cap gate command resources

[chasebryan]

Summary

• impose inherited hard limits on every copied gate command
• cap CPU time at 600 seconds per process, file growth at 512 MiB per file, open descriptors at 1,024, and real-user processes at 256
• prohibit core-file output and preserve any lower inherited host ceiling
• verify the effective ceilings in the protected helper test and document non-aggregate residuals

Verification

• scripts/ci/check-repository
  • policy 0.2.88
  • 288 Python tests
  • Rust debug and release suites: 162 + 74 + 32 + 9 tests each
  • two relocated optimized builds matched byte-for-byte
  • 7 documentation tests
  • final policy and source-identity checks passed

Residual risk

• these are inherited rlimits, not cgroup-wide budgets: CPU and file size apply per process and per file
• the process ceiling counts other processes with the same real user ID, and aggregate memory, process-tree CPU, and total temporary storage remain host boundaries

Rollback

Revert this commit to remove the helper resource ceilings and related policy, tests, and documentation.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve lower inherited soft limits

When the caller has already lowered a soft rlimit below these new caps while leaving the hard limit higher (for example a CI wrapper using a lower soft CPU or file-size limit), this code overwrites rlim_cur with maximum or the inherited hard value. That makes every sandboxed command start with more budget than the invoking environment's current limit, so the claimed preservation of lower inherited ceilings is bypassed in those runs; clamp the new hard/soft values against the inherited soft limit as well if lower caller limits should remain effective.

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