NEXUS. AI agent runtime in FastAPI

Problem

Building a developer brand means posting consistently, with quality, without burning hours. The tools that do this are paid SaaS: NEXUS runs those agents from one place, locally, on a laptop with no GPU.

Decisions

• A FastAPI runtime, with SQLite, running locally.
• Tests for every agent, run with pytest.
• One demo: Octave, the agency’s prospecting agent.
• Free models first (Groq, Cerebras, OpenRouter), rotated with automatic fallback and a cost cap in euros; the local Claude Code CLI for the content that matters.
• A single write thread to SQLite, so “database is locked” never happens.
• A frontend in native ES modules, no framework, no bundler.
• Nothing is sent or published without a human click.

Result

The full test suite passes. Octave runs on it as a demo.

What’s not done yet

• I never deployed it: NEXUS runs locally.
• The exit criterion for the post agent (10 real posts with nothing invented) is not measured by the code yet.
• Connecting the Telegram bot still means reading the API by hand: no setup assistant.