How do I install the Harness skill?

Run npx skillmds@latest add jasonkneen/harness in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Harness safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Harness?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Harness free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Harness?

jasonkneen (@jasonkneen) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Harness by jasonkneen — Agent Skill

Name: Harness
Author: jasonkneen

Harness

Continual harness — ranked scoped store for memories, skills, prompt notes, and subagent recipes. Auto-injected at session-start. Use to record durable lessons (add), load full entries, score helpful/unhelpful, and seed from playbook/learnings. Prefer this over freeform notes.md appends for anything that should affect future turns.

jasonkneen Updated Sep 17, 2026

File contents

Continual harness

Prime-agent-style persistent layer for lazar. One store, compact overview always injected by hooks/session-start.d/00-harness-overview.sh.

Paths

Global state: $LAZAR_HOME/memory/harness/state.json
History: $LAZAR_HOME/memory/harness/history.jsonl
Local (session): $LAZAR_HOME/memory/sessions/<id>/harness.json
CLI: python3 $LAZAR_HOME/skills/_meta/harness/harness.py

Kinds

Kind	Use for
`memory`	Durable facts, prefs, pitfalls
`skill`	Pointers to procedures / when-to-use a skill
`prompt`	Narrow behavioral addenda (not full SOUL rewrites)
`subagent`	Delegation recipes for `lazar-spawn`

Scope

global (default) — cross-session
local — this LAZAR_SESSION_ID only

Commands

# Compact overview (what session-start injects)
python3 $LAZAR_HOME/skills/_meta/harness/harness.py overview

# Record a lesson after success/failure
python3 $LAZAR_HOME/skills/_meta/harness/harness.py add \
  --kind memory \
  --title "short-slug" \
  --content "Specific actionable lesson" \
  --evidence "what happened"

# Load full entry; optional upvote
python3 $LAZAR_HOME/skills/_meta/harness/harness.py load M-never-cat-stream-log --helpful

python3 $LAZAR_HOME/skills/_meta/harness/harness.py helpful <id>
python3 $LAZAR_HOME/skills/_meta/harness/harness.py unhelpful <id>
python3 $LAZAR_HOME/skills/_meta/harness/harness.py delete <id>

# First-time / refresh seed (+ import playbook + learnings)
python3 $LAZAR_HOME/skills/_meta/harness/harness.py seed
python3 $LAZAR_HOME/skills/_meta/harness/harness.py stats

Rules

Smallest edit. One concrete lesson beats a paragraph dump.
Evidence. Prefer --evidence when refining from a real failure/success.
Global only if stable. Session-only progress → --scope local (needs session id).
Do not duplicate. add skips near-duplicate content unless --force.
Score usage. When an injected bullet actually helped, helpful <id>.
Still write long provenance to memory/distilled/ if needed — harness holds the ranked actionable slice.

When to write

User corrects you
Same failure twice
Stable preference discovered
Spawn pattern that should be reused
End of non-trivial task (1–2 bullets max)

---name: harnessdescription: Continual harness — ranked scoped store for memories, skills, prompt notes, and subagent recipes. Auto-injected at session-start. Use to record durable lessons (add), load full entries, score helpful/unhelpful, and seed from playbook/learnings. Prefer this over freeform notes.md appends for anything that should affect future turns.---# Continual harnessPrime-agent-style persistent layer for lazar. **One store**, compact overviewalways injected by `hooks/session-start.d/00-harness-overview.sh`.## Paths- Global state: `$LAZAR_HOME/memory/harness/state.json`- History: `$LAZAR_HOME/memory/harness/history.jsonl`- Local (session): `$LAZAR_HOME/memory/sessions/<id>/harness.json`- CLI: `python3 $LAZAR_HOME/skills/_meta/harness/harness.py`## Kinds| Kind | Use for ||------|---------|| `memory` | Durable facts, prefs, pitfalls || `skill` | Pointers to procedures / when-to-use a skill || `prompt` | Narrow behavioral addenda (not full SOUL rewrites) || `subagent` | Delegation recipes for `lazar-spawn` |## Scope- `global` (default) — cross-session- `local` — this `LAZAR_SESSION_ID` only## Commands```bash# Compact overview (what session-start injects)python3 $LAZAR_HOME/skills/_meta/harness/harness.py overview# Record a lesson after success/failurepython3 $LAZAR_HOME/skills/_meta/harness/harness.py add \ --kind memory \ --title "short-slug" \ --content "Specific actionable lesson" \ --evidence "what happened"# Load full entry; optional upvotepython3 $LAZAR_HOME/skills/_meta/harness/harness.py load M-never-cat-stream-log --helpfulpython3 $LAZAR_HOME/skills/_meta/harness/harness.py helpful <id>python3 $LAZAR_HOME/skills/_meta/harness/harness.py unhelpful <id>python3 $LAZAR_HOME/skills/_meta/harness/harness.py delete <id># First-time / refresh seed (+ import playbook + learnings)python3 $LAZAR_HOME/skills/_meta/harness/harness.py seedpython3 $LAZAR_HOME/skills/_meta/harness/harness.py stats```## Rules1. **Smallest edit.** One concrete lesson beats a paragraph dump.2. **Evidence.** Prefer `--evidence` when refining from a real failure/success.3. **Global only if stable.** Session-only progress → `--scope local` (needs session id).4. **Do not duplicate.** `add` skips near-duplicate content unless `--force`.5. **Score usage.** When an injected bullet actually helped, `helpful <id>`.6. Still write long provenance to `memory/distilled/` if needed — harness holds the *ranked* actionable slice.## When to write- User corrects you- Same failure twice- Stable preference discovered- Spawn pattern that should be reused- End of non-trivial task (1–2 bullets max)

Frequently asked questions