harn harness

harn harness list [--json]
harn harness show <id> [--json]
harn harness bench [harnesses...] [--require-installed] [--json]

harn harness is the executable source of truth for Harnery’s workflow adapters. The built-in registry intentionally contains three harnesses: claude-code, codex, and cursor.

The registry describes the Harnery adapter boundary, not every feature in the vendor product. For example, Cursor Agent can stream JSON, but Harnery’s workflow adapter currently returns only a normalized final result, so streaming is declared unsupported for that adapter.

Capability catalog

harn harness list prints the high-signal claims. harn harness show <id> prints every dimension, its support level, and its qualification.

Claims use four states:

State	Meaning
supported	The adapter implements the capability.
partial	A narrower form works; read the qualification.
unsupported	The adapter does not expose the capability.
unknown	Harnery does not have enough evidence to claim either way.

The current dimensions cover invocation, model and effort selection, turn ceilings, final results, session ids, cost, tool evidence, policy mapping, interruption, streaming, steering, resume, images, and compaction. Context continuity is split into four claims: context telemetry, a pre-compaction signal, a post-compaction signal, and the ability to initiate native compaction.

Conformance bench

harn harness bench runs without credentials and makes no model calls. It uses the same invocation planners and result normalizers as production workflow runs, then reconciles their observed behavior with the registry claims. A disagreement is drift and exits non-zero.

The full verdict vocabulary is:

Verdict	Meaning
supported / unsupported / partial	Observation agrees with the declaration.
unknown	No offline probe exists for that behavior yet.
skipped	The vendor binary is unavailable in this environment.
not_applicable	The dimension does not apply to the adapter.
drift	Executable behavior disagrees with the declared profile.

A missing binary is a neutral skip by default because the registry can be tested on machines that do not install every vendor CLI. Pass --require-installed when the current machine is expected to host every registered harness. --json emits the complete report for CI or dashboards.

The offline bench currently proves registration, binary availability, invocation planning, model and effort mapping, turn-ceiling mapping, final result normalization, session-id extraction, cost extraction, and the absence of normalized tool evidence. It also checks pre/post-compaction claims against the hook wiring that harn init installs. Context telemetry stays unknown in the offline bench because no static probe can prove a runtime measurement. Policy, active interruption, streaming, steering, resume, image input, and native compaction control remain unknown until a safe behavioral probe exists.

Workflow effort selection

Workflow agent() calls accept effort alongside model:

await agent("Review this patch", {
  harness: "codex",
  model: "gpt-5.6-sol",
  effort: "high",
});

Claude Code maps effort to --effort. Codex maps it to -c model_reasoning_effort="…". Cursor’s parameterized model ids can carry effort for some models, but Harnery deliberately does not rewrite model ids; separate Cursor effort requests fail before launch.