bounded-loops

Loop engineering you can actually run — every safety bound enforced in engine code, not described in a checklist.

63 runnable AI-agent loops across a dozen industries — keyless, offline, and gate-verified.
The runnable engine layer for the loop-engineering practice that Karpathy, Steinberger, Cherny, Osmani, and Berman defined.

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Clone this, and in ~30 seconds — no API key, fully offline — watch an AI-agent loop wreck without its gate (it confidently claims done while the bug is still there), then watch the same loop stop cleanly with the gate enforcing it. Every loop is a real runnable folder: a runner (the agent) proposes a change, an independent gate (pytest, a JSON-Schema check, a command, a real security scanner) verifies it, and a small engine repeats under nine enforced bounds + a kill switch until the gate passes or a bound trips.

"Loop engineering" is a practice the community named in 2026 — "stop prompting your agent; design the loop that prompts it." This repo doesn't claim the term; it ships the part others describe but don't run: the runnable, enforced implementation — 63 runnable loop folders across a dozen industries, plus a wider catalog of loop recipes. Full credits below.

Inspired by the loop-engineering community — we build on it, not against it

bounded-loops didn't invent loop engineering. It's the runnable engine layer for a practice that brilliant people defined first, and it exists to complement their work, not compete with it.

• Andrej Karpathy (@karpathy) framed the "loopy era" — the new skill is designing loops that keep useful work moving — and named the exact constraint this project is built around: you can only safely automate a loop when its result is easy to evaluate. bounded-loops turns that into code: the gate is that evaluable metric, and nothing is "done" until it passes.
• Peter Steinberger lit the spark: "stop prompting your agents; design the loops that prompt them."
• Boris Cherny (Claude Code, Anthropic): "My job is to write loops."
• Addy Osmani named the practice and gave it its anatomy in his Loop Engineering essay.
• Matthew Berman's Loop Library — the curated catalog of loops-as-prompts that we extend into runnable, gated folders.
• proof-loop, repo-task-proof-loop, and agentops pioneered the runnable fresh-verifier loop; bounded-loops adds the full nine-bound safety envelope and the by-industry library on top.

What bounded-loops adds to all of it: every loop is a real folder that runs to ✓ [DONE] under nine enforced bounds — across finance, legal, healthcare, retail, operations, enterprise/ERP, security, testing, content, research, and business, not just software. If we've mischaracterized or missed your loop project, open an issue — this space grows by building on each other.

Three ways to use it

1. As a CLI — clone, pip install -e ., then bl list / bl run loops/<name> --yes. The raw engine; see Quick start below.
2. As an MCP server — the bounded-loops-mcp command exposes bl_run / bl_lint / bl_list to any MCP client (Claude Code, Cursor, Codex, Antigravity…).
3. As an agent plugin — plugins/ ships a ready-to-install package for Claude Code, Codex, and Antigravity, each with a Skill, a /bl-run command, the MCP wiring, and a verify-on-stop hook. Inside your agent you get gate-verified "done" instead of the agent claiming done. See MCP server and IDE plugins.

Repository layout

bounded-loops/
├── bounded_loops/      the engine (Python package)
│   ├── domain/           pure rules + data types, no I/O — the ports (the seam) live here
│   ├── application/      the loop algorithm (run_loop.py) + bounds enforcer + manifest loader
│   ├── adapters/         concrete runners (stub, shell, claude-code, codex, …) and
│   │                     gates (command, pytest, jsonschema, osv, checkov)
│   ├── composition.py    the ONLY file that wires adapters onto the engine (composition root)
│   ├── cli.py            the `bl` command
│   ├── mcp_server.py     the `bounded-loops-mcp` server (bl_run / bl_lint / bl_list)
│   └── hooks/            the verify-on-stop hook
├── loops/              the 67 runnable loop folders — the library (each = seed + gate + cassette)
├── catalog/            the recipe catalog — a browsable menu of loop ideas across industries
├── docs/               how the engine works — ARCHITECTURE, NINE-BOUNDS, WRITING-A-LOOP (SVG diagrams)
├── plugins/            install packages for Claude Code / Codex / Antigravity (skills, commands, hooks)
├── tests/              the 619 tests
└── README.md · CONTRIBUTING.md · LICENSE · pyproject.toml

docs/ explains how the machine works; catalog/ lists which loops you can run — different jobs, not duplicates. Every other top-level entry (.venv/, __pycache__/, the .*_cache/ dirs) is a local build artifact that .gitignore already excludes from the repo.

Install

The engine is a Python 3.11+ package. Install it whichever way fits your stack:

pip — native, recommended

pip install bounded-loops            # from PyPI
bl list

# …or from source, today:
git clone https://github.com/qualixar/bounded-loops
cd bounded-loops && pip install -e .

npx — Node convenience wrapper (still needs Python 3.11+ on your PATH)

npx bounded-loops list
npx bounded-loops run loops/bug-fix-red-green --yes

The npm package is a thin launcher: on first run it finds Python 3.11+, installs the engine, then hands off to the real CLI. It does not reimplement the tool in Node — Python is the engine, npm is just a convenient front door.

Quick start (keyless, ~30s)

pip install -e .
bl run loops/bug-fix-red-green --yes    # keyless stub runner + real pytest gate

✓ [DONE] gate-passed (laps: 1)  ledger: loops/bug-fix-red-green/.ledger.jsonl

See the contrast that makes the point — the same loop, ungated, believing a lie:

cd loops/bug-fix-red-green && ./wreck.sh    # exits 1: "LIE CONFIRMED"

And browse every loop with its role, rung, and gate:

bl list

Nine bounds (+ kill switch)

Every loop's bounds.yaml maps onto nine bounds, enforced across the engine's layers — not nine flat booleans in one file:

#	Bound	Enforced by
1	Iteration control — hard lap cap + no-progress stall detection	bounds.max_iterations / bounds.no_progress_window, in run_loop.py
2	Sandboxing — the agent operates on an isolated scratch copy of seed/, never the source dir; symlinks refused	bounds.sandbox + composition._make_scratch_workspace
3	Input quarantine — secret-bearing files (.env*, .ssh, .aws, *.pem/*.key, id_rsa, credentials, .git) are excluded from the sandbox copy, so a shared loop can't smuggle or exfiltrate credentials	bounds.quarantine_inputs (active in _make_scratch_workspace)
4	Output schema validation	bounds.schema, consumed by JsonSchemaGate when a loop opts in
5	Tracing — one OTel span per lap, or a no-op tracer when the otel extra isn't installed	bounds.trace + TracerPort
6	Regression evaluation — satisfied by the loop's gate choice (pytest / command / jsonschema / osv / checkov), not a Bounds field	the GatePort adapter a loop selects
7	Token budget — real token counts parsed from claude-code's usage, accumulated and enforced by BudgetMeter. (shell/codex/antigravity report 0 tokens — an honest tool limitation, not a silent gap; stub/python_callable supply counts from the cassette/glue.)	bounds.max_tokens + BudgetMeter
8	Human approval gating	bounds.require_approval (derived from rung when unset: L1 → none, L2/L3 → required)
9	Wall-clock timeout — max_wallclock_s: null means "use the conservative 1-hour default", not "unbounded". It is an inter-lap ceiling (checked before each lap); the in-lap guard against a single long turn is the runner's and gate's own subprocess timeout_s	bounds.max_wallclock_s + BudgetMeter; runner/gate timeout_s

On top of all nine, an env-var kill switch (BOUNDED_LOOPS_KILL) is polled once per lap, before anything else — the highest-priority stop. And a frozen invariant runs through all of it: the engine never trusts the agent's own claim of "done." Only the gate decides. The runner's agent_claimed_done flag is recorded but never substituted for a real gate pass.

Runners and gates

Runners (what proposes a change each lap):

Runner	What it does	Needs
stub	Replays a recorded cassette of agent turns — fully deterministic, zero external calls. The keyless demos (including the osv/checkov loops' quick path) use this: the cassette simulates the agent's fix so the loop runs offline. To exercise a real agent/scanner, install the tool and use --runner or a non-stub cassette	nothing (keyless)
shell	Pipes the loop's prompt to any CLI command over stdin	whatever CLI you point it at
python_callable	Calls a run_turn(prompt, workspace) -> dict in a spawn-isolated subprocess with a scrubbed env	a Python module implementing the contract
claude-code	claude -p --output-format json --bare; parses real total_cost_usd + usage tokens	the claude CLI and ANTHROPIC_API_KEY/apiKeyHelper — --bare never reads OAuth/keychain (confirmed against the real binary)
codex	codex exec --json, sandbox mode derived from rung	the codex CLI (JSON schema not yet smoke-tested against a real binary — see Known limitations)
antigravity	agy -p, approval policy derived from rung	the agy CLI

Gates (what decides if a lap is done):

Gate	Checks	Needs
command	Any command (tokenized, run without a shell — no |/&& chaining); exit 0 = pass. Verifies by exit code only — for real output validation prefer a typed gate below. A gate needing shell features ships a wrapper script in its loop folder	whatever command you configure
pytest	pytest -q in the workspace	pytest
jsonschema	workspace/output.json against a JSON Schema (path from bounds.schema)	nothing beyond the core deps (keyless)
osv	osv-scanner reports zero known vulnerabilities (fails closed on an empty/garbage report)	osv-scanner binary + network (fetches the OSV.dev advisory DB)
checkov	checkov reports zero failed IaC checks (fails closed on uninterpretable output)	checkov

Additional gate adapters are pluggable via the composition root; the default install ships only the universal, keyless-first set above — no gate in any shipped loop's default manifest requires a paid product.

Runnable loops (67 folders, across a dozen industries)

Every one is a real folder you run to DONE — a broken seed, a mechanical gate, the nine bounds, an L1/L2/L3 rung, and a forbid: guard so the agent can't rewrite the gate to cheat. 63 of the 67 reach ✓ [DONE] gate-passed with zero setup (keyless stub runner + a real gate); the 4 framework examples need their framework installed. bl list prints them all — here's the spread:

Industry / role	#	Examples
Software · backend · dev	12	bug-fix-red-green, data-contract, openapi-schema-valid, dead-import-clean, type-annotations-present, json-config-schema
Security · supply-chain	7	secret-scan-keyless, dependency-pinning, dockerfile-no-root, cors-not-wildcard, jwt-alg-not-none, osv-scanner-example
Finance · accounting	6	ledger-reconciliation, invoice-3way-match, journal-entries-balance, iso20022-payment-valid, fx-rate-sanity
Legal · compliance	6	citation-existence-check, contract-clause-extraction, nda-required-clauses, gdpr-dpa-terms, contract-defined-terms
Content · marketing	6	content-fact-gate, frontmatter-schema, broken-internal-links, alt-text-present, reading-level-gate, seo-meta-limits
Retail · commerce	5	product-feed-schema, price-margin-floor, inventory-nonnegative, gtin-checkdigit, catalog-required-fields
Operations · SRE	5	runbook-completeness, oncall-coverage, slo-error-budget, conventional-commits, alert-runbook-link
Enterprise · ERP/SAP	5	idoc-xml-schema, transport-request-manifest, cds-view-annotations, bapi-payload-contract, material-master-completeness
Business alignment	5	okr-measurable, prd-acceptance-criteria, rfc-decision-recorded, roadmap-field-contract, meeting-action-items
Testing · QA	4	test-naming-contract, assertion-density, no-hardcoded-sleep, test-presence-per-module
Research pipeline	4	claim-source-mapping, dataset-license-allowed, reproducibility-manifest, bibliography-completeness
Healthcare · frontend	2	clinical-note-completeness, a11y

The flagship for "AI reliability" is citation-existence-check: a runnable form of the single most-documented AI failure in law — fabricated case citations (1,600+ sanction cases catalogued by mid-2026) — where the gate fails until every cited case resolves to a real one.

Every loop's own README shows the "prove the gate genuinely fails on the unfixed seed, then passes on the fix" walkthrough with actual captured output — run, not asserted. The wider recipe catalog lists more loop recipes across these same industries (each naming a real gate) to wire up next.

On accessibility specifically: axe-core/Lighthouse need a running browser, and no keyless universal a11y tool exists — so the a11y loop ships a small, dependency-free static linter (missing alt, missing lang, unlabeled inputs). It's honest about catching the static WCAG subset, not rendered-DOM issues.

Scaffolding your own loop

bl new --list                    # pytest-basic, jest-basic, go-test-basic,
                                 # cargo-test-basic, rspec-basic, junit-basic
bl new pytest-basic my-loop      # <template> <destination> (positional)

MCP server and IDE plugins

bounded-loops-mcp exposes bl_run/bl_lint/bl_list as MCP tools — a thin shim over the same engine the CLI uses. bl_run's confirm is a real, server-side-enforced gate: it binds the full run identity (gate + runner + iteration cap), so a caller can't preview a safe shell runner and then confirm a credentialed one; and a loop needing interactive approval is refused before it's ever wired. plugins/{claude-code,codex,antigravity}/ each ship the MCP config + an AGENTS.md snippet + a verify-on-stop hook.

Known limitations (stated plainly, not hidden)

• The codex runner's real-binary JSON schema is not yet smoke-tested (no codex install at build time); its token accounting reports 0 until verified.
• langgraph-example's glue hard-codes changed: True — its no-progress bound can't fire for that example; a real integration should diff before/after.
• Two gates are not offline, and require network at check time: content-fact-gate (link liveness) and the osv gate (osv-scanner fetches the OSV.dev advisory database). The "~30-second, no-API-key, fully offline" quick-start refers to the default bug-fix-red-green loop specifically (stub runner + pytest gate), which needs neither network nor a key. The keyless-first set — stub/shell runners with pytest/jsonschema/command gates — is offline; the security-scanner gates (osv, checkov) bring their own binary and, for osv, a network fetch.
• python_callable always spawns and scrubs the child env to a small allowlist — by design, but your callable's import side effects run in a clean environment.

Contributing

See CONTRIBUTING.md — bl new a template, replace the seed, prove your gate genuinely fails then genuinely passes, and open a PR. The bar for a catalog recipe or a loop: a real gate and a testable done-condition, never "an LLM decides."

Citation

bounded-loops is research-grade software from the Qualixar AI Reliability Engineering initiative. If it's useful in your work, please cite it — GitHub's "Cite this repository" button reads CITATION.cff:

@software{bhardwaj_bounded_loops_2026,
  author    = {Bhardwaj, Varun Pratap},
  title     = {bounded-loops: runnable, bounded AI-agent loops},
  year      = {2026},
  publisher = {Qualixar},
  version   = {0.1.0},
  url       = {https://github.com/qualixar/bounded-loops}
}

Security

Found a way to trick the gate or escape a bound? That's the most valuable bug we can get — please report it privately per SECURITY.md.

License

Apache-2.0. Copyright © 2026 Varun Pratap Bhardwaj / Qualixar.

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Part of the Qualixar AI Reliability Engineering initiative

bounded-loops is one product in Qualixar's open-source platform for making AI agents reliable:

Product	Purpose	Install
SuperLocalMemory	Local-first agent memory + learning	npm install superlocalmemory
Qualixar OS	Universal agent runtime	npx qualixar-os
SLM Mesh	P2P coordination across sessions	npm i slm-mesh
SLM MCP Hub	Federate 430+ MCP tools	pip install slm-mcp-hub
AgentAssay	Token-efficient agent testing	pip install agentassay
AgentAssert	Behavioral contracts + drift detection	pip install agentassert
SkillFortify	Formal verification for agent skills	pip install skillfortify
Agent Amplifier	Runtime amplification hooks	pip install agent-amplifier
bounded-loops (this repo)	Runnable, gate-verified agent loops	pip install bounded-loops

Local-first. Honest about what runs. Built to complement the ecosystem, not fence it off.

Start here → qualixar.com · Author: Varun Pratap Bhardwaj — founder, Qualixar.

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If bounded-loops saves you from an agent that lies about being done,
⭐ star it on GitHub — it helps other developers find it.