gate prepare's package-mode Briefing omits required context field, breaking direct --review-v1 floats

[clkao]

Description

spacedock gate prepare writes a canonical Briefing (gate-briefing.json) that omits the context field. subspace-tui's Briefing loader (internal/reviewv1/loader.go, validateBriefing) requires Context != nil and refuses to load any Briefing missing it:

briefing: context is required

Reproduction

1. Run spacedock gate prepare <entity> --question "..." --artifact <file.md> --summary "..." --workflow-dir <dir> to open a gate room.
2. Inspect the emitted gate-briefing.json — it contains only type, version, id, question, and artifacts. No context key at all.
3. Attempt to float that Briefing directly via the canonical package-mode review form:

   subspace-tui --review-v1 --actor <actor> --mode <mode> <path-to-gate-briefing.json>
   

4. The process exits immediately (exit 2) with briefing: context is required, before any review UI opens — the reviewer never sees anything.

Scope

Confirmed independently on two separate, unrelated entities/gate stages within the same workflow — not a corrupted or one-off file. Every gate prepare-authored Briefing observed has the same gap.

Why this has gone unnoticed

The common workaround (used throughout, apparently unintentionally) is to float the plain-Markdown form instead (review-<terminal> --mode <mode> <artifact.md>), which builds its own compliant Briefing internally and never touches the package-mode loader path — so it never hits this. Anyone who directly floats a gate prepare-authored Briefing via the raw --review-v1 <briefing.json> form hits this every time.

Environment

• spacedock version: 0.27.0 (workflow originally commissioned under 0.19.9)
• Workflow: split-root, single-repo, id-style sd-b32