to-spec

name	to-spec
description	Produce a specification document at docs/specifications/ — problem, solution, user stories, acceptance criteria, testing seams, and scope for a feature. The engineering source-of-truth a plan later implements. Use when the user wants a spec or says /to-spec, or when another skill needs the spec phase before planning.
allowed-tools	Bash(git config:*), Bash(date:*), Glob, Grep, Read, Write

To Spec

A spec is the engineering source-of-truth: what to build and the definition of done. It is stable — it outlives plan revisions — because it carries no file paths and no code snippets. Those go stale, so they belong to the plan, where they can be kept current. Spec is the stable what; the plan is the volatile how.

Normally invoked by architect after research; also runs standalone.

Input

Determine what to specify, in priority order:

1. Invoked from architect with a build goal and research context → use those.
2. A spec worked out in the current conversation → capture that; do not start over.
3. Otherwise → ask the user what to build; if the request is vague, elicit intent first via clarify.

Detect the primary language from the repo so acceptance criteria target the right test runner; fold the detection into whatever you ask next rather than blocking on it. Non-code work → language is N/A.

Gather context

Read all docs/research/*.md. Explore the codebase to understand current state, using the project's domain vocabulary, and read docs/adr/ so the spec does not contradict a decision already made.

Identify testing seams

Map where the feature's behaviour will be exercised by tests. A seam is a point where a test observes behaviour:

• Prefer existing seams over new ones.
• Position each seam as high in the architecture as it goes — a boundary (API, CLI, HTTP handler) over an internal call.
• The fewer seams, the better; the ideal is one.

Confirm the seams with the user before writing them into the spec.

Write the acceptance criteria

Feature/boundary behaviour → delegate to behaviour-spec, passing the feature description and language. Take its acceptance-criteria block (Gherkin) for the spec's ## Acceptance Criteria section. Leave its scaffold tasks for the plan — they are implementation, not spec.

Non-code work (docs, config, operational) → author Given/When/Then prose directly, verified by checkable assertions (grep, command output, file state); skip behaviour-spec.

Write the spec

Write to docs/specifications/<yyyy-mm-dd>-<slug>.md. Date from date +%F, author from git config user.name. A new spec's Status is Draft.

# {Feature Name} — Specification

- **Status**: Draft
- **Author**: {git config user.name}
- **Created**: {YYYY-MM-DD}
- **Language**: {confirmed language, or "N/A" for non-code}

## Problem Statement

{User-facing description of what is wrong or missing.}

## Solution

{User-facing description of what will exist when this is done.}

## User Stories

1. As a {actor}, I want {capability}, so that {benefit}.

## Acceptance Criteria

The definition of done — feature-level Given/When/Then. From
`behaviour-spec` for code; prose scenarios verified by
grep/command/file-state for non-code.

```gherkin
Feature: {capability}

  Scenario: {one concrete behaviour}
    Given {a starting state}
    When {an action occurs}
    Then {an observable outcome holds}
```

## Testing Seams

Where this feature's behaviour is exercised. Prefer existing seams,
positioned high; ideal count is one.

- {Seam} — {what it covers, why chosen}

## Implementation Decisions

Interfaces, contracts, schema changes, and API shape — **no file
paths, no code snippets** (those live in the plan).

- {Module / interface / contract, and the decision about it}

## Out of Scope

- {Explicitly excluded, to bound the work.}

## Research

- [topic](../research/<yyyy-mm-dd>-topic.md)

## Open Questions

- {Unresolved decisions or risks.}

Guidelines

• The spec stays stable: name interfaces, contracts, schema, and API shape — never their file location or an implementation snippet.
• Extract from research and code; do not invent. Cite claims — path:line for code, URL for docs — and label anything you cannot cite an unverified assumption.
• Follow conventions-markdown and omit needless words — see ../shared/CONCISE-PROSE.md.