SKILL: gherkin-authoring

Purpose

Produce valid, consistently named Gherkin story files. Handles ID allocation, timestamp generation, filename construction, tag formatting, and scenario validation. Used by the product-owner agent whenever a new story is written or updated.

Story File Naming Convention

<epic-slug>-<story-slug>-<timestamp>-<NNNN>.md

Part	Format	Example
epic-slug	kebab-case, 2–4 words	user-auth
story-slug	kebab-case, 2–5 words	reset-password
timestamp	YYYYMMDDHHMMSS	20250416143000
NNNN	4-digit zero-padded, sequential within epic	0003

Full example: user-auth-reset-password-20250416143000-0003.md

Allocate the Next Story ID

# Count existing stories for an epic to get next sequential ID
EPIC="user-auth"
NEXT_ID=$(ls docs/stories/${EPIC}-* 2>/dev/null \
  | grep -oE '\-[0-9]{4}\.md$' \
  | grep -oE '[0-9]{4}' \
  | sort -n | tail -1 \
  | python3 -c "import sys; n=sys.stdin.read().strip(); print(f'{int(n)+1:04d}' if n else '0001')")
[ -z "$NEXT_ID" ] && NEXT_ID="0001"
echo "$NEXT_ID"

Generate Filename

EPIC="user-auth"
STORY="reset-password"
TS=$(date -u +"%Y%m%d%H%M%S")
ID="$NEXT_ID"   # from allocation step above
FILENAME="${EPIC}-${STORY}-${TS}-${ID}.md"
echo "$FILENAME"   # user-auth-reset-password-20250416143000-0001.md

Story File Template

Every story file must contain:

---
id: "{EPIC}-{NNNN}"
title: "{Human-readable story title}"
epic: "{epic-slug}"
priority: "high|medium|low|critical"
ui: false
adr_required: false
milestone: "{milestone name}"
labels:
  - "type:feature"
  - "priority:high"
  - "phase:discover"
issue_number: null
issue_url: null
---

## Story

**As a** {actor},
**I want** {capability},
**so that** {business outcome}.

## Acceptance Criteria

```gherkin
@story:{EPIC}-{NNNN} @epic:{epic-slug} @priority:{level}
Feature: {Feature title}

  Scenario: {scenario title}
    Given {precondition}
    When {action}
    Then {expected outcome}

Definition of Done

• All Gherkin scenarios have passing step implementations
• Unit tests written and passing
• Integration tests written and passing (if applicable)
• Code reviewed and approved
• No regressions in related features
• Documentation updated (if applicable)

ADR Links

## Gherkin Validation Rules

Before writing a scenario, verify:

1. **Single responsibility**: each `Scenario` tests exactly one behavior.
2. **Given-When-Then order**: never skip or reorder.
3. **No implementation detail in steps**: steps describe intent, not code.
4. **Declarative steps**: `Given the user is logged in` ✓ — `Given I call POST /auth/login` ✗
5. **Tags present**: `@story:`, `@epic:`, `@priority:` required on every Feature block.
6. **No `And` as first step**: `And` is only valid after a `Given`, `When`, or `Then`.

## Background Block (shared preconditions)

```gherkin
Feature: Password Reset

  Background:
    Given the user has a verified account
    And the account is not locked

  Scenario: Successful reset request
    When the user submits their email address
    Then a reset link is sent to that address

Use Background when 2+ scenarios share the same preconditions.

Scenario Outline (data-driven)

  Scenario Outline: Reject invalid email formats
    When the user submits "<email>"
    Then they see a validation error "<message>"

    Examples:
      | email        | message                  |
      | notanemail   | Invalid email format     |
      | @nodomain    | Invalid email format     |
      | a@b          | Domain must have TLD     |

Tags Reference

Tag	Required	Description
@story:{id}	Yes	Links scenario to story file
@epic:{slug}	Yes	Groups stories by epic
@priority:{level}	Yes	critical, high, medium, low
@wip	No	Work in progress — excluded from CI by default
@ui	No	Requires browser/UI driver
@integration	No	Requires external services
@smoke	No	Runs in production smoke suite

Failure Modes

Condition	Action
Story ID collision (same NNNN exists)	Re-run allocation step. Never overwrite an existing file.
docs/stories/ does not exist	Create it: mkdir -p docs/stories/
Scenario has no When	Invalid — split into two scenarios or add action step
Missing required tags	Add tags before writing the file
Title exceeds 72 characters	Shorten. Titles appear in issue headings and PR titles.

Logging

[gherkin] ALLOCATE  epic=user-auth  next_id=0003
[gherkin] CREATE    docs/stories/user-auth-reset-password-20250416143000-0003.md
[gherkin] VALIDATE  scenarios=3  tags=ok  structure=ok