openprose__prose/packages/std/patterns/ratchet.prose.md

name, kind

name	kind
ratchet	pattern

Ratchet

Advancer proposes steps, certifier validates. Certified progress is never rolled back.

Description

Advancer proposes incremental steps; certifier validates each one; certified progress is never rolled back.

Metadata

• version: 0.1.0

Slots

• advancer (primary)
  • requires: task_brief, certified_progress, rejection feedback (if prior rejection)
  • ensures: proposed next step
• certifier
  • requires: task_brief, certified_progress, proposed step
  • ensures: certify or reject verdict

Config

• max_steps (integer, default: 5): Maximum advancement attempts

Invariants

• Progress is monotonic — the certified_progress array only grows, never shrinks
• The advancer does not know a certifier will evaluate its proposals
• The certifier does not know its verdicts drive a retry loop
• Rejected steps are discarded, never appended to certified progress

Shape

• self: manage the advance-certify loop, maintain certified progress log
• delegates:
  • advancer: propose the next incremental step
  • certifier: certify or reject the proposed step
• prohibited: none

Requires

• Pattern instance receives: advancer: string -- service or system name for the advancer certifier: string -- service or system name for the certifier task_brief: string -- the overall goal max_steps: number -- (optional, default 5) certified_progress: any[] -- (optional, default []) — prior certified steps

Ensures

• Advancer receives the task brief plus all certified progress so far
• Certifier receives the proposed step and decides: certify or reject
• Certified steps are appended to certified_progress — never removed
• Rejected steps are discarded — advancer receives the rejection reason and proposes differently
• Progress is monotonic: the certified_progress array only grows
• result: the final certified progress

Delegation

let certified_progress = certified_progress
let rejection_feedback = null

repeat max_steps:
  let proposal = call advancer
    task_brief: task_brief
    certified_progress: certified_progress
    rejection_feedback: rejection_feedback

  let verdict = call certifier
    task_brief: task_brief
    certified_progress: certified_progress
    proposed_step: proposal

  if verdict certifies the proposal:
    append proposal to certified_progress
    rejection_feedback = null
  else:
    rejection_feedback = verdict

return {
  result: certified_progress
}

Notes

The advancer does not know a certifier will evaluate its proposals. The certifier does not know its verdicts drive a retry loop. The structural guarantee is monotonic progress — once a step is certified, it is committed. This is valuable when rollback is expensive or when partial progress must be preserved across failures.