@nbt-dev/harness

Everything a chat session IS: the harness language, the capability model, the standard harness library, the tools an agent holds, the agent loop itself — and what the agent's output LOOKS like.

The console compiles manifests natively in Jai. The TypeScript compiler here is still intentional: the browser editor validates authoring in-process, the published npm CLI builds projects under Node, and scripts/test-manifest-port.sh holds both implementations to byte-identical output and diagnostics.

The package is split by whether React is involved, not by package boundary. Everything above /blocks/view is React-free and runs unchanged inside the console's QuickJS eval executor; scripts/build.mjs builds that half platform: neutral so a stray renderer import is a build error rather than a silent 260 KB in the eval bundle.

| subpath | what | |---|---| | @nbt-dev/harness | the harness spec + HARNESS.md contract | | /markdown /library /catalog | the compiler, the shipped harnesses, abilities & policies | | /tools | every tool, one directory each — see src/tools/README.md | | /blocks | every transcript block — one directory each, meta.ts + block.tsx + BLOCK.md. React-free barrel: metadata, registry, prompt | | /blocks/view | the same blocks WITH their renderers, the fence dispatcher, AgentMarkdown | | /ui | the shadcn primitives everything here composes on (/ui/utils is cn) | | /design | the DESIGN.md token model + theme generator | | /saved-view /crm /calendar /dashboard | the renderers for what an agent emits | | /styles.css | the standalone .nbt-ui stylesheet | | /tools/registry | which tools exist, with none of the implementations | | /session | the agent loop, the bridges a host plugs into, the stores | | /protocol/* | the console's wire and spec contracts (auth, dashboards, views, workflows) | | /manifest | the nbt.dev/v1 kinds |

HARNESS.md is the canonical serialization of one harness. Import the compiler from @nbt-dev/harness/markdown and capability resolution from @nbt-dev/harness/catalog.

This package ships the harness compiler and runtime, and no harness content. It carried four of them once (default, builder, analyst, compute) under harnesses/*/HARNESS.md, inlined by a generator into a /library subpath and re-baked into the core cart by a second script. Both pipelines are gone: a harness now lives with whatever owns it. Builder ships from cartridges/core/harnesses, Compute ships with nbt-dev/cartridges/compute, and Analyst was deleted as a duplicate of the default.

The one exception is @nbt-dev/harness/default-harness: the Assistant fallback, as markdown source. It is here because it has to resolve with no rows, no carts, no filesystem and no network, since it is what a session falls back to before the first fetch returns and after one fails.

Every harness declares abilities explicitly. toolset remains the runtime mode (full, readonly, or compute), but it does not grant tools by itself. Empty abilities: [] is valid only for compute, whose fleet tool is supplied by that mode.

Component workbench

Run npm run build once, then npm run dev. The block workbench opens at http://127.0.0.1:6120 and watches the package source, declarations, styles, and every registered block. Its Live tab can stream a model turn without booting a console.

Abilities may scope entity-facing tools to exact qualified entity names. The scope is an attenuation, not a replacement for the caller's authorization:

subAbilities:
  - id: appointments
    label: Read GHL appointments and contacts
    description: Query only the CRM records needed by this harness.
    tools: [query]
    entities:
      - ghl:GhlAppointment
      - ghl:GhlContact

The selected ability's query tool rejects other targets locally and sends the same scope to the console data plane, where it is intersected with normal user/entity authorization. Exact cart:Entity handles are required; an unscoped ability that also grants the same tool makes that tool unrestricted, because abilities compose additively.

The bundled templates are inert: installing or upgrading this package does not modify a live instance.