Overview

Sigil is a skill compiler. You write a skill as plain markdown; Sigil compiles it into a typed agent harness — a program the model runs inside, so every step, rule, and check in the skill is enforced by structure rather than hoped for in a prompt. See skill-compilation for the pipeline.

Everything the compiler produces and needs lives on one persistent object-spatial graph — compiled skills, configuration, memory — there are no config files on disk.

The two-tier economics

A frontier model is paid once, at compile time, to author the typed procedure (the AG-IR) that the compiler lowers and gate-checks. From then on a cheap, small, even fully-local model executes the compiled harness — the structure a weak model would skip is no longer skippable.

How a request flows

• sigil compile ./SKILL.md [-e out.jac] — the explicit path: compile a skill onto the graph; -e also ejects one self-contained runnable program.
• sigil solve "<task>" — the compiler applied at runtime: route the task against the compiled-skill library (HIT — run it on the cheap model), compile a new skill for a new class of task (MISS), or recompile an existing one to cover a near-match (PARTIAL). See memory-and-skills.
• Chat mode (sigil chat) — a conversational agent over the same graph: files, shell, web, cron, memory, skills, MCP, channels, parallel sub-agents. See chat-and-tools.

The graph (the compiler's persistent memory)

graph LR
    root((root)) -->|Embodies| Soul
    root -->|Anchored| Registry
    Soul -->|Knows| Spec["Spec — the AG-IR contract"]
    Soul -->|Remembers| Memory["Memory — durable facts"]
    Soul -->|Owns| Registry
    Registry -->|Crystallized| TaskGraph["TaskGraph — a compiled skill"]
    TaskGraph -->|Ran| Attempt["Attempt — one run"]
    TaskGraph -->|MutatedFrom| TaskGraph

The Soul node holds all configuration — persona, model tiers, workspace, sandbox mode, channels, policies. awaken() rebinds the agent's cognition from the graph on every run, so a configure change takes effect on the next turn with no restart.

Interfaces

• sigil chat — the conversational REPL (markdown, live tool trace, inline approvals).
• sigil <command> — one-shot CLI (solve, soul, configure, cron, channel, docs, models, teach, recall, …). Run sigil with no args for the full list.
• sigil serve (= jac start observatory.jac) — the full-stack server: REST API + the Observatory web UI (live agent-graph + token observability), plus the api_inbound webhook for channels.