An alarm pauses the job, not the escalation

The physical worldMQTTDashboardline-alarmprint_errorpausedresumedMachines.handoffDecisions

A 3D printer on the lineStep 6 of 7Unloaded, or a decision for a person

27% into the boat, the spool runs dry. The printer stops and waits.

← Milestones on the escalation Rehearse with a simulated machine →

A filament runout opens a servicing escalation and notes the pause on the print. Resuming at the printer closes the alarm, and the print escalation resolves at the finish.

The situation

A printer that runs out of filament is paused, not failed. Someone has to load a spool and press resume, and the print should carry on as the same job. A printer that refuses a print, or stops for good, needs a decision instead. Built by hand, both end up as a failed job and a retry. Here the two read differently.

The setup

The printer pauses with print_error 134184977. The codec reads it as an alarm:

{
  "alarmId": "print-error",
  "level": "critical",
  "code": "07FF-8011",
  "text": "The external spool ran out of filament. Load filament and resume the print.",
  "active": true,
  "jobId": "Pmw8druzy-p1s-01",
  "raisedAt": "2026-11-08T22:05:25.810Z",
  "clearedAt": null
}
// gateway: a line-alarm escalation on print-servicing,
//          paused:print-error:2026-11-08T22:05:25.810Z on the print escalation

On the floor

A line-alarm escalation goes to print-servicing: “The external spool ran out of filament. Load filament and resume the print.” The print escalation gains paused:print-error:<at> and stays open. Someone resumes at the printer, print_error returns to 0, the alarm escalation resolves itself, and the print escalation gains resumed:print-error:<at>.

A refused print, or one that stops unfinished, resolves the hop with an errorCode, and the route asks the line’s operator role:

Real dashboard formSimulated backend

/** Ask until the operator picks one of the decisions this failure allows. */
async function askOperator(input: UnitRouteInput, hop: Hop, attempt: number, senderAttempt: number, outcome: HopOutcome): Promise<OperatorResolution> {
  const where = stationName(hop.from, 'line entry');
  const decisions = handoffDecisions(outcome.errorCode);
  let refused = '';
  for (let round = 1; ; round++) {
    const answer = await conditional<OperatorResolution>(signalKeys.handoffError(input.routeKey, hop.index, attempt, round), {
      role: input.operatorRole ?? LINE_ROLE.OPERATOR,
      type: ROW_TYPE.HANDOFF_ERROR,
      subtype: outcome.errorCode,
      description: `${refused}${input.units.map((u) => u.unitId).join(', ')} stopped at ${where}: ${outcome.errorCode}. ${outcome.detail ?? ''} Choose ${decisions.join(', ')}.`.replace(/\s+/g, ' ').trim(),
      priority: 1,
      workflowType: UNIT_ROUTE_WORKFLOW,
      metadata: {
        ...hopFacets(input, hop, attempt, senderAttempt), errorCode: outcome.errorCode, detail: outcome.detail ?? null, decisions, round,
      } as Record<string, unknown>,
      timeout: input.operatorTimeout ?? OPERATOR_TIMEOUT,
    });
    if (!answer) return { decision: DECISION.SCRAP, note: 'no decision before the timeout' };
    if (decisions.includes(answer.decision)) return answer;
    refused = `${answer.decision} is not available here. `;
  }
}

{
  "title": "Line decision",
  "description": "A handoff that did not complete: retry it, finish the units by hand, or scrap them. Units a machine finished as not ok are off the line: finish them by hand or scrap them. An alarm or a machine that went dark: acknowledge it once handled.",
  "x-lt-order": [
    "decision",
    "note"
  ],
  "required": [
    "decision"
  ],
  "properties": {
    "decision": {
      "type": "string",
      "enum": [
        "retry",
        "manual",
        "scrap",
        "acknowledge",
        "cleared",
        "restored",
        "approve",
        "reject",
        "release",
        "rework"
      ],
      "default": "acknowledge",
      "description": "One of the row's decisions for a failed handoff; acknowledge for an alarm or a machine"
    },
    "note": {
      "type": "string",
      "format": "textarea",
      "default": "",
      "description": "What was done"
    },
    "clearedBy": {
      "type": "string",
      "default": "",
      "description": "Who cleared it at the machine, when the machine reports it"
    }
  }
}

Choose retry, manual or scrap for the refused print.

The guarantee

A pause never resolves the print escalation, and the alarm closes when the printer clears it. A failure always reaches a person on the line’s operator role, who chooses from the decisions that fit it. See Machines.

The physical world