Higgs

Routing email through a cloud inference API undoes end-to-end encryption in a single request. higgs is a CLI tool built specifically for Proton Mail users who will not make that trade. It connects to your inbox via Proton Mail Bridge running on 127.0.0.1, sends mail to a locally hosted model — Gemma 4 via Ollama by default, or any OpenAI-compatible server like llama.cpp via `PM_LLM_BACKEND=openai` — and returns structured output. The vendor describes three core commands: `classify` (suggests labels with confidence scores), `search` (filter by folder, date, and other criteria), and `archive` (acts on UIDs piped from search). No byte leaves the machine. No cloud API key is required. No telemetry exists in the codebase.

The differentiating feature is the agent contract. Most CLI tools are written for humans and retrofitted for agents, which means the agent has to parse prose help text, regex unstructured stdout, and branch on English error strings that vary between versions. higgs inverts this: `higgs schema ` returns a JSON manifest of flags, argument types, stdout format, and exit codes as a typed enum. NDJSON output streams one object per line and terminates with a guaranteed `{“type”:”summary”}` object, so an orchestrating agent reads until that terminator rather than waiting on a timeout. The docs describe this as a deliberate engineering choice, not a convenience feature.

This tool fits a narrow but specific profile: a privacy-focused individual or team running Proton Mail who wants to drop AI-assisted triage into an agent framework without standing up cloud infrastructure. It also fits developers building agents who need a well-specified CLI tool to drive as a reference integration. It breaks outside that profile. Only Proton Mail is supported — there is no IMAP generic mode, no Gmail connector, and no Exchange path. Classification accuracy is bounded by whatever local model you can run on your hardware; a 7B model on a laptop will not match a cloud frontier model on ambiguous mail. There is no GUI, no browser extension, and no mobile path. Teams that need multi-provider inbox support or higher classification accuracy on low-resource hardware will move to a cloud-based mail AI tool despite the privacy trade-off.

Installation is via Homebrew (`brew install higgscli/higgs/higgs`), `go install`, or signed release tarballs. Releases are cosign-signed with an accompanying SBOM so you can verify the exact build. The project is Apache-2.0 licensed and the vendor states zero telemetry — no analytics, no crash reporting, no update pings.