Empirical Verification in Terminal AI Runtimes: Non-Bypassable Policy Gates and Isolated Sandboxing

1. Introduction & Background

When an artificial intelligence agent executes coding tasks inside a developer workstation, the host machine is exposed to arbitrary system calls. Traditional approaches treat the agent as an interactive human user, granting full bash shell access.

Our investigations across >1,200 simulated developer failure scenarios revealed that without a strict policy intermediary:

• 34.2% of agent runs attempted destructive out-of-bounds file modifications.
• 18.7% leaked ambient environment variables (such as AWS keys or GitHub tokens) into prompt contexts.
• 42.1% falsely reported that failing tests had passed when the compiler crashed or timed out.

To solve this, we implemented the M31A Empirical Verification Engine, combining OS-level sandboxing, deterministic policy gating, and atomic two-phase checkpointing.

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2. Platform Process Confinement

The runtime enforces platform-specific hardware and kernel isolation barriers before executing any subprocess requested by the reasoning model:

2.1 Linux cgroups v2 & Namespaces

On Linux systems, child processes spawned by M31A are assigned to a transient cgroup node with hard resource ceilings:

# /sys/fs/cgroup/m31a-sandbox/
memory.max = 2147483648       # 2.0 GiB ceiling
memory.high = 1879048192      # 1.75 GiB soft throttling
cpu.max = 200000 100000       # 2 cores max (200ms per 100ms period)
pids.max = 128                # Fork-bomb protection

In addition, user and mount namespaces detach the sandbox from the host root directory, mounting only the targeted project directory with restricted MS_NODEV | MS_NOSUID flags.

2.2 macOS Seatbelt Sandbox

On macOS Darwin kernels, M31A compiles an on-the-fly Seatbelt profile (sandbox_init) restricting file reads and writes strictly to the canonical repository path:

(version 1)
(deny default)
(allow process-exec (literal "/usr/bin/cargo") (literal "/usr/bin/rustc"))
(allow file-read* (subpath "/path/to/project"))
(allow file-write* (subpath "/path/to/project/target") (subpath "/path/to/project/src"))
(deny network*)

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3. Two-Phase SQLite WAL Crash Recovery

A major operational hazard in autonomous engineering is the interrupted execution state: the host loses power or the process is terminated mid-refactor, leaving syntax errors across dozens of files.

M31A implements a two-phase commit protocol backed by SQLite in Write-Ahead Log (WAL) mode:

[Phase 1: Pre-Execution Snapshot]
  1. Capture git object SHA-256 for all targeted files
  2. Record planned DAG mutation manifest into SQLite
  3. BEGIN EXCLUSIVE TRANSACTION;

[Phase 2: Execution in Sandbox]
  1. Apply file diffs to staging buffer
  2. Run compiler diagnostics & test suites
  3. Verify SHA-256 hash tree matches expectations

[Commit or Rollback]
  - If SUCCESS: Write post-state SHA-256 digest; COMMIT;
  - If FAILURE: Rollback staging buffer; emit structured error;
  - If ABNORMAL CRASH: On next boot, M31A replays WAL journal,
    detects unsealed transaction, and restores pre-execution snapshot.

Crash Recovery Invariant Testing

We subjected the two-phase recovery engine to 500 simulated hard SIGKILL terminations during active file writes:

Test Condition	Trials	Recovered Cleanly	Work Loss	Corruption Rate
SIGKILL during File Staging	150	150 (100%)	0 files	0.0%
SIGKILL during Compiler Pass	150	150 (100%)	0 files	0.0%
SIGKILL during SQLite WAL Commit	100	100 (100%)	0 files	0.0%
Simulated Host Kernel Panic	100	100 (100%)	0 files	0.0%

In all 500 trials, M31A verified repository integrity upon reboot and rolled back incomplete partial writes without user intervention.

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4. Conclusion & Availability

Empirical verification shifts autonomous software development from probabilistic wishful thinking to verifiable systems engineering. M31A is open source and actively maintained at github.com/eshanized/M31A.

@techreport{roy2026empirical,
  title={Empirical Verification in Terminal AI Runtimes: Non-Bypassable Policy Gates and Isolated Sandboxing},
  author={Roy, Eshan},
  institution={Tonmoy Infrastructure & Vision},
  number={M31A-RES-2026-002},
  year={2026},
  month={September},
  url={https://eshan.tonmoyinfrastructure.org/research/empirical-verification-terminal-runtimes}
}