arn-code-feature-spec

Arness Feature Spec

Develop a feature idea into a well-formed specification through iterative conversation, aided by architectural analysis from the arn-code-architect agent and, when the feature involves UI, user experience design from the arn-code-ux-specialist agent. This is a conversational skill that runs in normal conversation (NOT plan mode). The primary artifact is a feature specification written to the project's specs directory that captures requirements, architectural assessment, and decisions from the exploration conversation. The spec then informs plan creation via the /arn-code-plan skill.

Step 0: Ensure Configuration

Read ${CLAUDE_PLUGIN_ROOT}/skills/arn-code-ensure-config/references/step-0-fast-path.md and follow its instructions. This guarantees a user profile exists and ## Arness is configured with Arness Code fields before proceeding.

Workflow

Step 1: Capture the Feature Idea

1a. Detect Backlog Feature (Greenfield Path)

Before asking the user to describe their feature, check if the trigger includes a greenfield feature backlog entry:

1. Check if the trigger message contains an F-NNN pattern (regex: F-\d{3}). Accept natural invocations like:

   • feature spec F-002
   • spec F-002: Device Pairing
   • feature spec: Device Pairing (fuzzy match against feature file names in the features directory)

2. Check if conversation context from arn-code-pick-issue includes feature file content (look for markers: ## Description, ## Journey Steps, ## Acceptance Criteria that indicate an F-NNN file was passed inline).

3. If either condition is met: extract the feature ID and proceed to Step 1b.

4. If neither condition is met: fall through to the standard flow below (ask the user to describe the feature).

1b. Load Greenfield Feature Context

Only runs when a backlog entry is detected in Step 1a. Loads the feature file, referenced UC documents, and scope boundary context (related features from the Feature Tracker) to provide rich context for the spec exploration. If any greenfield artifact is missing, falls back gracefully.