LLeMbas-CLI/harness

The harness spec

LLeMbas CLI (a terminal coding agent, TypeScript) and LLeMbas (a self-hosted web UI, Python) are two independent projects that share one harness design: the same tools, the same permission design, the same prompt texts, the same model quirks and model metadata. This directory writes that design down as data. Each project implements it in its own language; neither ever runs the other. LLeMbas CLI embeds these files at build time; LLeMbas vendors a pinned, hash-checked copy.

The concept-by-concept map of the two implementations, and where they still differ, is the wiki page Harness-parity.

What is here

Path	What
VERSION	The spec's own version, apart from LLeMbas CLI's
purpose.json	The purpose argument added to a tool whose calls say what they are for
tools/<name>.json	One tool each: name, scope, risk, exclusive, block (how a call is shown: shell, edit, read, search, web, task, hidden, tool), purpose, former names (aliases, per project), renamed arguments, the description and the JSON Schema of its parameters — exactly what a model is sent
prompts/	The prompt texts; prompts/index.json says which are shared and which LLeMbas fragment each one is. prompts/personality/ holds the personality presets both offer
permission/hardline.json	The floor: commands refused in every mode, protected paths, and how a command is spelled plainly before it is checked again
permission/arity.json	How much of a command an "always allow" covers
permission/defaults.json	The rules every session starts from
permission/modes.json	The four modes — manual, edit, auto, plan — as what each does with each risk class
models/schema.json	Model metadata: context, output limit, efforts, vision, tools, notes, capacity
loop.json	How one prompt runs: the step backstop, budgets, wrap-up, nudges, parallel calls, capacity
quirks.json	What real servers do, and how both harnesses cope
conformance/<area>.json	Cases with their expected results, run by both test suites
acp.md	The link between them: ACP plus every _lembas/* method, field and capability

Vocabulary

• Risk classes: read, write, execute, interact. Reading and writing are never one tool among the shared ones, so a read-only helper is given exactly the readers.
• Modes: manual, edit, auto, plan (unrestricted is read as auto).
• Scopes: shared — both projects implement it; cli or llembas — only that one. The same two names key what is per project elsewhere: a tool's aliases, loop.json's budgets, a protected path's scope.
• A tool's other names, per project, are listed in its aliases and work as the tool.

1.0.0

The spec as described here: the shared tools with their scopes, risk classes, call blocks and aliases; the prompt texts and the six personality presets; the permission floor, arity table, default rules and the four modes; model metadata; the loop; the quirks of real servers; the conformance cases; and acp.md, the link between the two projects (_lembas protocol 2, every feature beyond protocol 1 gated on its capability string).

Variables in a description

A description may hold {{name}} where the two projects differ in a fact, not in design — a timeout's default, whether commands may run in the background, which subagents exist. The tool's variables says what each one means; each project fills them before sending the description, and none may reach a model unfilled.

Changing it

1. Change the spec first, and bump VERSION: patch for a text or a new conformance case, minor for a new tool, rule or field, major for a rename or a removed tool.
2. A fix comes with a conformance case that fails without it. In LLeMbas CLI, bun run harness record fills in the expected result of a new case from the implementation, and bun run harness record --all shows every case whose result would change.
3. Implement it in both projects — in the same session, or with an open item recorded against the other. A bug found in one is searched for in the other.
4. Nothing here names a host, a path on a server or anybody's setup: both projects are public.

Licence: MIT, as LLeMbas CLI. Files that came from elsewhere say so in their source field (Hermes Agent's hardline patterns, OpenCode's arity table) or in an HTML comment (prompt texts).