---
type: trekbrief
brief_version: "2.1"
created: 2026-05-14
task: "Fixture: v5.1 brief WITHOUT phase_signals or partial (falsification target)"
slug: brief-v21-no-signals
project_dir: .claude/projects/2026-05-14-brief-v21-no-signals/
research_topics: 0
research_status: complete
auto_research: false
interview_turns: 4
source: fixture
---

# Task: brief_version 2.1 without phase_signals

## Intent

Falsification fixture for the v5.1 sequencing gate. The brief declares
`brief_version: "2.1"` but omits BOTH `phase_signals` AND
`phase_signals_partial: true`. The brief-validator MUST emit
`BRIEF_V51_MISSING_SIGNALS` for this file — the runtime test for the
sequencing gate asserts the error code fires.

## Goal

Validate that brief-validator catches the missing-signals scenario.

## Success Criteria

- brief-validator returns valid: false.
- errors contains BRIEF_V51_MISSING_SIGNALS.