safe-mini

A bounded local-execution substrate with policy guards for mini-swe-agent–style bash-action coding agents.

Fresh worktree copies, scoped HOME, a sanitized environment, and explicit command policies. The built-in executors run commands in the host process context; isolation requires an injected executor boundary.

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What this is

safe-mini is the load-bearing runtime substrate for mini-swe-agent–style coding agents that decide one bash command at a time within a budget.

Current and planned consumers:

Consumer	Role
JustAi	Explicit, opt-in source adapter over the public runner contract.
local-resident	Planned research harness — benchmark corpus + calibration matrix.

safe-mini is intentionally generic: it does not know about its consumers' domain models. Future projects can ship on top of the same substrate.

What lives here

• Runner loop — prompt → one bash action → observation → repeat
• Action protocol parsers — fenced bash block, JSON action object
• Executor policies — open / safe / allowlist (and future variants)
• Observation policies — full / tail / headtail / structured / structured+raw-tail
• Worktree provisioner — fresh copy of repo per run, scoped HOME, sanitized PATH
• Command/path guard — built-in regex policy checks before host-process execution
• Failure classifier — 7-class taxonomy
• Run transcript — in-memory per-step records carried in RunResult
• Canonical types — Chunk, Budget, RunResult, FailureClass, ObservationPolicy, ExecutorPolicy
• AgentRunner Protocol — the contract consumers depend on

Failure taxonomy

Class	Meaning
safety-violation	Agent attempted an action the executor policy denied.
action-protocol-violation	Output didn't parse as a valid action.
exhausted-ideas	Budget remained but the loop converged without progress.
budget-exhausted	Move or observation budget hit the cap.
context-starvation	Observations truncated below decision-relevant detail.
reward-hacking	Test passed by means unrelated to the requested change.
embodiment-failure	Action ran but didn't produce the expected world-state change.

Two-axis budget

Every run is bounded on TWO axes:

• Move budget — how many bash actions the agent can execute.
• Observation budget — how many characters of output the agent can read.

Both are enforced inside the runner. Either axis can independently fire BUDGET_EXHAUSTED.

Installation

Note: safe-mini is in alpha. Not yet on PyPI. Pinning options below.

From git (Phase A — current)

pip install 'safe-mini @ git+https://github.com/JustinJLeopard/safe-mini.git@17c8514c1bf42d3064748400745099ca1723e782'

From source (development)

git clone https://github.com/JustinJLeopard/safe-mini.git
cd safe-mini
python3 -m venv .venv
source .venv/bin/activate
pip install -e '.[dev]'

pytest -q
ruff check safe_mini tests
mypy safe_mini

From PyPI (Phase B — pending stabilization)

pip install safe-mini  # not yet published

Status

Current source state: alpha (package metadata 0.1.0). The reference implementation from the pre-public 54-trial calibration study is preserved under reference/ for transparency. The production package under safe_mini/ now includes the concrete SafeMiniRunner, action parser, executor policies, observation handling, worktree provisioning, and integration tests. The injectable executor boundary supports explicit consumers such as JustAi.

This records source integration only. It is not package-install, live-model, productive-runtime, or release evidence.

Empirical baseline (from the lab study, 6 task families × 9 configs × 54 trials):

These are deterministic reference-study results, not proof of host isolation, release readiness, or broad real-model performance.

• "Open" executor leaked a fake credential 6 / 6 probe runs while still solving the task.
• "Safe" executor blocked 6 / 6 probes and still solved 6 / 6 tasks.
• reproduce_first workflow: 2 steps avg vs 3 for inspect_first.
• headtail and structured observations beat pure tail on noisy output (tail dropped early failure clues).
• JSON and fenced-bash action protocols equivalent in deterministic tests; live-model malformed-action rate is the open question.

The lab study artifacts:

• reference/lab_safe_mini_agent.py — the original 270-line single-file agent loop
• reference/lab_benchmark_tasks.py — the 6-task corpus
• reference/lab_benchmark_safe_mini.py — the matrix-runner

The production runner components have been factored into this package. The benchmark harness remains separate work for local-resident.

Three-repo architecture

safe-mini is one of three repos:

        ┌─────────────────────────┐         ┌────────────────────────────┐
        │      JustAi             │         │      local-resident        │
        │  (orchestrator)         │         │  (researcher harness)      │
        └────────────┬────────────┘         └──────────────┬─────────────┘
                     │                                     │
                     └──────────────┬──────────────────────┘
                                    ▼
                            ┌──────────────┐
                            │  safe-mini   │
                            │ (this repo)  │
                            └──────────────┘

Contributing

This is currently a personal-research-stage project. Issue reports and design discussions welcome via GitHub Issues. PRs accepted after issue-first design review for non-trivial changes.

License

MIT — see LICENSE.