Harness Engineering

Harness Engineering

An agent workflow, runtime environment, tools, data sensitivity, effects, cadence, risk, and operator constraints. An auditable runtime kernel with scoped permissions, scheduling, observability, recovery, and eval controls. An end-to-end trace and failure-path tests prove bounded, replayable, recoverable delegated action. Business-task decomposition, prompt-only safety, broad credentials, or unbounded scheduled autonomy.

Treat the harness as the kernel around an LLM OS: context is RAM, durable state is disk, tools are system calls, skills are programs, the scheduler is control, and evals are verifiers. Load references/runtime-control-patterns.md for matrices and schemas.

Usage Template

Provide: workflow, users, agent roles, environment, tools/connections, data sensitivity, delegated actions, cadence, throughput/SLA, failure history, and risk tolerance.

Workflow

Run the trace gate: the harness must be able to show what the agent saw, decided, called, changed, and verified. Separate Agent (instructions/capabilities), Environment (network/files/credentials), and Session (mounted context/events/state). Define one auditable control path for high-risk intent and final joins.

If state ownership, credential scope, external side effects, retention, or approval authority is unclear, return NEEDS_INPUT. Probe tools with read-only discovery where possible; unknown side effects default to denied.

1. Pass Four-C: Context truth/retrieval, Connections scoped accounts/APIs, Capabilities versioned skills/scripts/evals, Cadence trigger/receipt/anomaly/stop.
2. Map runtime: stored program, control unit, hot context, durable disk, event bus, I/O tools, verifier, and garbage collector.
3. Choose the lowest-context primitive: deterministic script/hook, skill,

static Graph, connector, dynamic workflow, or agent team. Load capabilities lazily. Graph Engineering owns dependency semantics; the harness owns the ready queue, leases, duplicate delivery, concurrency, and executor health.

1. Define each tool as a narrow system call with purpose, explicit inputs, bounds, timeout, idempotency, failure path, evidence, and audit location.
2. Enforce least privilege in the environment, not only prose. Escalate autonomy through observe -> co-drive -> scoped reversible action -> monitored routine -> audited low-risk autonomy.
3. For delegated action require mandate, scope, limit, preview, receipt, and rollback. Human approval governs irreversible/shared/financial/published/credentialed actions.
4. Add deterministic feedback (tests, lint, LSP, policy checks) outside context when possible; add independent evaluator/red team for high-risk semantic output.
5. Persist an append-only session event log and checkpoint; define alerts, fallback, incident response, cleanup, permission review, and stale-context/rule review.
6. For scheduled work define Trigger, Context, Steering, Receipt, budget, stop, recovery, and executor health. A schedule firing is not task success.
7. For Graph execution, persist node/edge/join transitions before releasing

successors, make delivery idempotent, recover from the last verified checkpoint, and test permission denial, worker loss, duplicate events, and compensation without relying on in-memory scheduler state.

Threat-model normal, denied, timeout, partial-write, stale-context, duplicate-trigger, compromised-input, evaluator-disagreement, and rollback paths. Verify permissions with actual environment boundaries and run an independent end-to-end trace. Adoption fails if operators cannot inspect or recover the system.

max_attempts: 3 per tool/failure class. Retry only idempotent or compensated actions after changing diagnosis/strategy. Use exponential delay for transient dependencies. Stop on repeated signature, permission denial, ambiguous side effect, or NO_PROGRESS.

Persist {run_id, status, attempt, budget, evidence, unknowns, last_error, next_action} plus agent/environment/session versions, context manifest, tool/permission registry, event offsets, approvals, evals, alerts, recovery point, and rollback receipts. State transitions are auditable and replayable.

Failure Protocol

• NEEDS_INPUT: ownership, effect, retention, or approval authority is ambiguous.
• BLOCKED_PERMISSION: deny the call and continue with a safer read-only path when useful.
• BLOCKED_DEPENDENCY: checkpoint, back off, and expose executor health.
• VERIFY_FAILED: trace, eval, guardrail, or rollback test fails; block autonomy escalation.
• NO_PROGRESS: changed attempts repeat the signature. max_attempts: 3.
• BUDGET_STOP: stop scheduler/workers, checkpoint, and emit a recovery receipt.

Output Contract

Return status, result (runtime architecture and controls), evidence (trace/eval/failure tests), unknowns, and next_action including approval or rollback.

Edge Cases

• A connector exposes broad account access for a narrow task: create a scoped proxy/allowlist or keep the workflow manual; instructions alone are insufficient.
• The scheduler ran on time but the state store was stale: block mutation, mark the run failed, and recover from the last verified checkpoint.
• A Graph worker completes twice after lease expiry: deduplicate by node/run

identity and release successors only from one verified transition.

Success Metrics

• Every delegated action is bounded, observable, independently verifiable, and recoverable.
• Runtime state can be replayed across sessions without relying on chat history.
• Autonomy level follows measured reliability and operator review capacity.

Quality Gates

• [ ] Agent, Environment, Session, and serial control ownership are explicit.
• [ ] Tool effects are enforced by real permissions and contracts.
• [ ] Independent eval, approval, manual fallback, and rollback match risk.
• [ ] Schedules have executor receipts, hard budgets, stop, and recovery.
• [ ] Maintenance includes cleanup, permission audit, and rule half-life.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Mark393295827
• Source: Mark393295827/third-brain-v7-skills
• License: MIT
• Homepage: https://github.com/Mark393295827/third-brain-v5-skills/tree/master

Install and usage instructions live in the source repository linked above.