journey-runner.js rung 2 silently skips a span claim that is only negative (ordered: [] + mustNotFire) #150

What happens

Rung 2 in project-tests/e2e/journey-runner.js (~l.726) runs only when step.spans.ordered is non-empty:

if (step.spans && step.spans.ordered && step.spans.ordered.length) {
  ...
  for (const n of step.spans.mustNotFire || []) O.assertNotFired(...)
}

mustNotFire is therefore honoured only next to a positive list. A step whose whole proof is "this did NOT run" is one example: Cancel on a "Reset all state?" confirmation, where the reset microflow must not fire and nothing fires at all. Such a step cannot say so.

spans: { ordered: [], mustNotFire: ["ACT_X_Reset"] } is skipped with no output. The journey file reads as if it declares a trace claim, and the claim proves nothing.

Evidence (card-disbursement requirements-driven build, 2026-09-26)

Writing span claims for a 9-step admin-console journey. That step was left with no span claim, and its data rung (rows unchanged) carries the proof.

Why this is not a one-line guard change

With nothing fired, O.capture(t0, {min: 1, …}) returns zero spans. The existing branch then reports INVALID "zero spans captured — Jaeger down or OTel off". So "correctly nothing ran" and "tracing is broken" look the same. A negative-only claim needs a liveness reference:

• a span the step is known to produce, such as the page's own data-source retrieve or the button's nanoflow; or
• a Jaeger health/services query taken in the same window.

Suggested fix

1. Run rung 2 when ordered or mustNotFire is non-empty.
2. For a negative-only claim, wait the normal capture window (there is nothing to until on). Then assert no match, gated on a liveness check so an empty capture is not read as a pass.
3. Emit a loud INVALID when a step declares spans that rung 2 will not evaluate, instead of skipping silently.
4. Add a positive-control mutant that injects the forbidden name into the captured list. --positive-control already has a trace-negative rung (~l.506) that assumes an ordered list; it needs a branch for this.

Files

• project-tests/e2e/journey-runner.js: rung 2, positive-control trace-negative mutant
• project-tests/e2e/otel.js: capture
• skills/testing-shape.md / skills/journey-proof.md: claim shapes