---
id: TRIG-1
family: RT-TRIG
level: extended
profiles: [runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-trig/trig-1
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# TRIG-1 — Overlap is judged against the workflow's own unfinished runs

*RT-TRIG (Part II) · level: extended · profiles: runtime · added in 1.0*

The overlap decision is made unattended, and a wrong answer is either a duplicated production run or a silently dropped one. The four policies are four genuinely different behaviours, and the buffer is a one-slot mailbox rather than a queue.

## The rule

> **Normative.** This is the rule.
>
> 1. Overlap is decided against runs of the same workflow that have not reached a terminal state: pending, running or paused.
>
> 2. A terminal run, and a run of any other workflow, are both ignored; with none active, every policy proceeds with the caller's trigger data unchanged.
>
> 3. With one active, Skip blocks the firing; Buffer defers it and blocks; Cancel cancels every active run, announcing each cancellation, and proceeds; Terminate first cancels every job those runs still have outstanding, so no worker can pick one up after the run is gone, and then does what Cancel does.
>
> 4. The buffer holds at most one deferred firing per trigger: a second firing while one is buffered is dropped, never stacked and never overwritten.
>
> 5. A buffered firing is released at the next firing once the run that blocked it is terminal or gone, and on release its own payload replaces the current firing's; a buffer whose blocking run can no longer be identified is released rather than left stranded.
>
> 6. A policy an implementation does not recognise must be treated as Skip, the only fail-safe direction, since every alternative destroys a running workflow.

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.