FE-812: Completed-spec fixture for the plan emitter

[kostandinang]

Summary

Adds a realistic completed-spec fixture for the emitter to run against, plus a reusable skill for producing more of them. spatial_graph_layout is a brunch feature specced as a full completed specification — four interview phases closed, requirements and criteria reviews accepted — seeded into .brunch/brunch.db as scenario spatial-graph-layout-all-phases-closed. It gives the emitter (and the workspace UI) believable input beyond the single thin real spec.

The graph is authored for coverage: full criterion→requirement verification, one criterion verifying two requirements, non-buildable constraint-phrased requirements, and zero req→req execution edges (so ordering must be synthesized, not read) — exercising the emitter's projection, ordering, and reconciliation stages.

What Changed

• Adds src/server/fixtures/scenarios/spatial-graph-layout.ts — the completed-spec seed (25 knowledge items, 16 typed edges, all four phases confirmed, per-turn impact), registered in scenarios.ts as spatial-graph-layout-all-phases-closed.
• Adds docs/fixtures/spatial-graph-layout-interview.md — the four-phase interview transcript and node/edge capture map (source of truth for the seed).
• Adds the spec-fixture skill (.agents/skills/spec-fixture/) — a standalone, profile-parameterized workflow for authoring further completed-spec fixtures from any feature, so dogfooding the emitter and UI is repeatable rather than a one-off hand-build.

Scope

Fixtures and tooling only — no product or emitter code changes. Completed-spec fixtures live in their own scenarios/ sub-tree to keep the scenarios.ts registry lean as the family grows. The seed is additive (a new specification row); existing scenarios and DB state are untouched.

Verification

npm run verify passes: format and lint, full test suite, production build. The seeded scenario produces 25 items / 16 edges with all four phases confirmed against a fresh DB.

Run: npm run seed -- spatial-graph-layout-all-phases-closed

Closes FE-812.

🤖 Generated with Claude Code

[kostandinang]

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• FE-812: Completed-spec fixture for the plan emitter #168 👈 (View in Graphite)
• FE-800: Spec to orchestrator plan emitter — generate plan.yaml from a completed specification #167 : 1 other dependent PR (#170 )
• FE-764: Brunch<> Petrinaut stream — ephemeral orchestrator hosted SSE server #165
• FE-784: Petrinaut export: colour-fold per-slice subnet #160
• FE-763: Petrinaut event stream — initial markings + transition firings #158
• FE-762: Petrinaut-format JSON export of the compiled net #157
• FE-761: Petri-net semantic alignment for Petrinaut visualization #156
• FE-755: Cook codebase mode for brownfield brunch #155
• FE-747: Declarative output routing for branching transitions #154
• FE-745: Epic-scoped sandbox merge for verify-epic #152
• FE-743: Petri parallel execution with resource pools and per-slice sandboxes #149
• FE-738: Petri semantic lanes with two-lane subnet and engine factory #148
• FE-730: Greenfield orchestrator POC with pi-agent dispatch #143
• main

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PR Summary

Low Risk
Fixtures, docs, and agent skill only; no runtime product or emitter logic changes. Existing scenarios unchanged aside from one new registry entry.

Overview
Introduces a realistic completed-spec fixture for the plan emitter and UI dogfooding: scenario spatial-graph-layout-all-phases-closed seeds a brownfield spatial graph layout spec (four phases closed, accepted requirements/criteria, 25 knowledge items, 16 policy-guarded edges) via new seedAcceptedSpatialGraphLayoutSpec in src/server/fixtures/scenarios/spatial-graph-layout.ts, wired through scenarios.ts and npm run seed.

The graph is authored for coverage stress: full verifies on buildable requirements, multi-target criteria, non-buildable constraint-phrased requirements without verification, no req→req depends_on, and an adversarial refines edge—so downstream consumers must synthesize order and validate, not read execution deps from the graph.

Adds docs/fixtures/spatial-graph-layout-interview.md as the transcript + capture map kept in sync with the seed, and the spec-fixture agent skill (with references/seed-pattern.md) documenting how to produce additional completed-spec fixtures with coverage or clean profiles.

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