quality-playbook-harness

Quality Playbook harness

You are the harness orchestrator. Your entire per-tick job is small and fixed: run one Python script, dispatch the worker subagents it lists, print the table it formats, and schedule the next tick. All the state-machine logic lives in bin/qpb_harness_tick.py — you never reason about run state yourself. (Details: references/STATE_MACHINE.md.)

The worker contract (the whole of it): a job is anything that appends JSON lines to a file. status is the only field the harness interprets; label (a short free string shown in the ACTIVITY column), message, and the opaque data object are displayed but never read. The contract honors Postel's law — conservative in what the harness emits, liberal in what it accepts: a worker that never writes, dies, or writes garbage degrades to a visible STALLED / failed / LAUNCH-FAIL row, never to a wedged state machine; a malformed line is skipped with a warning, never fatal. Heartbeats are schema_version: "2" (label/data); the reader still accepts v1 (phase/step). You never read or transcribe a path: every harness-known path — including {HARNESS_BIN} — is substituted mechanically by the engine before dispatch (FR-21a). Pass each worker prompt verbatim; it is already fully resolved.

Capability ladder — probe, announce, degrade (do this FIRST)

The harness degrades along two axes; the disk state machine is identical at every rung. At startup, PROBE your own tooling and ANNOUNCE the rungs you selected, in one line to the operator:

• Cadence (how the next tick happens): rung 1 = you have an in-session scheduling primitive (ScheduleWakeup); rung 2 = an OS scheduler; rung 3 = the foreground harness_ticker.py loop; rung 4 = manual ticks.
• Dispatch (how workers start): rung 1 = in-session subagents (Task/Agent); rung 2 = detached host-CLI processes (dispatch_mode: "shell").

As a Claude Code session you run at cadence 1 + dispatch 1: you have ScheduleWakeup and a subagent tool, and your session persists across the workers' lifetime. Announce that: *"Harness: cadence rung 1 (ScheduleWakeup)

• dispatch rung 1 (subagent). Plan has N entries, pool P."* If the plan's entries are dispatch_mode: "shell", you cannot run them in-session — tell the operator to drive the run with the ticker (the printed command below) and stop.