Foxxception Releases Halligan, an Open-Source Tool That Finds the Turn Where AI Guardrails Break

JACKSONVILLE, Fla. (August 15, 2026) Foxxception LLC today released Halligan, a free, open-source tool for testing whether an AI assistant keeps its guardrails across a whole conversation, not just the first message. Halligan is available now on PyPI with pip install halligan.

AI assistants rarely break on the first request. They break three or four turns in, after a user has built a little rapport, reframed the question or applied steady pressure. And because model responses vary, a guardrail that holds once can fail the next time the same conversation runs. Halligan is built to catch both.

Key features

• Multi-turn escalation: scripted adversarial conversations that apply pressure turn by turn, to find the exact turn where a guardrail gives way.
• Repeat runs with flake rates: --repeat runs each test several times and reports how often it fails, so inconsistent behavior shows up.
• Drift detection: consistency suites that flag when a model's answers to the same question start to change.
• CI build gates: Halligan fails the build when a guardrail moves, so regressions are caught before release.
• Cost preview and HTML reports: --estimate shows what a run will cost before it starts, and every run produces a shareable report.
• Works with the major model providers: Anthropic, OpenAI and Gemini, local models through Ollama and LM Studio, or any custom HTTP endpoint.
• Probe packs and policies: a domain-neutral policy template, age-safety suites, and a Catholic-aligned pack for faith-based AI assistants.

Halligan grew out of a real red-team session against a faith-based AI assistant that held seven of eight escalating "rungs" before giving way on the last. That session became the first test suite.

"A guardrail that holds on turn one and fails on turn four isn't a guardrail," said Jeremy Foxx, founder of Foxxception. "Halligan finds that fourth turn before your users do, and it does it every time you ship."

Halligan runs entirely on the developer's machine or CI: there is no hosted service, no account and no telemetry.

Availability

Halligan is available now under the Apache 2.0 license at halligan.dev and on GitHub, and installs with pip install halligan. It is free to use, with no paid tier.