Arness Implementing

Execute an implementation plan, run a quick implementation (swift), run a standard-tier implementation, or manage the build-simplify-review cycle. This is a first-citizen entry point that orchestrates arn-code-execute-plan, arn-code-swift, arn-code-standard, arn-code-simplify, arn-code-review-implementation, and related execution skills. Chains from arn-planning and chains to arn-shipping or arn-assessing at completion.

This skill is a sequencer and decision-gate handler. It MUST NOT duplicate sub-skill logic. All implementation work is done by the invoked skills. Arness-implementing handles: input routing, state detection, execution mode selection, the simplify/review cycle, and chaining.

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.

After Step 0 completes, extract the following from ## Arness:

• Plans directory — for detecting structured plans and project folders
• Code patterns — path to stored pattern documentation
• Template path — path to report templates

Workflow

Step 0: Input Routing

Check the trigger message for swift or standard intent:

• "swift: [description]", "quick: [description]", "quick change: [description]", or "quick implementation: [description]" detected: → Route directly to the Swift Path (Step S1). Skip all state detection.

• "standard: [description]" or "standard mode: [description]" detected: → Route directly to the Standard Path (Step ST1). Skip all state detection.

• No swift or standard intent detected: → Proceed to Step 1 (State Detection).

Step 1: State Detection

Check which artifacts exist on disk to determine the entry point. Check from most advanced to least advanced — first match wins:

If multiple projects detected (more than one subdirectory in plans-dir with artifacts): list them with their states and ask the user which to implement.

If artifacts detected for a single project: ask: "Resume [project-name] at [detected stage], or start fresh?"

• Resume → skip to the detected gate
• Start fresh → begin at G0/G2 (do not delete existing artifacts)

Step 2: Gate G0 — No Plan Fallback

Only reached when no structured plan or swift artifacts are found.

Show progress:

Implementing: [no plan detected]

Ask (using AskUserQuestion):

"No implementation plan found. What would you like to do?"

Options:

1. Quick implementation — Describe a small change for swift mode
2. Go to planning first — Run /arn-planning to create a spec and plan

If Quick implementation: Ask for a description, then route to Swift Path (Step S1). If Go to planning first: Skill: arn-code:arn-planning. After planning completes and chains back, re-run state detection (Step 1). If the scope router assigned standard tier, route to Standard Path (Step ST1) instead of full execution.

Step 3: Auto — Taskify (conditional)

If state detection found INTRODUCTION.md but no TASKS.md, run taskify automatically:

Inform: "Creating task list from plan..."

Skill: arn-code:arn-code-taskify

After taskify completes, proceed to G2.

Step 4: Gate G2 — Execution Mode

Show progress:

Implementing: EXECUTE -> simplify -> review-impl -> [ship]
              ^^^^^^^

Ask (using AskUserQuestion):

"How should the tasks be executed?"

Options:

1. Sequential with review gates (Recommended) — Each task is executed and reviewed before the next
2. Parallel with Agent Teams — Tasks run in parallel using Agent Teams (higher token cost)
3. One task at a time — Execute tasks manually, one at a time

Based on choice:

• Sequential → Skill: arn-code:arn-code-execute-plan
• Agent Teams → Skill: arn-code:arn-code-execute-plan-teams
  • If Agent Teams is not available (environment variable not set), inform the user and suggest sequential instead.
• One at a time → Skill: arn-code:arn-code-execute-task
  • After each task, the user controls which task to run next. When the user is done or all tasks are complete, proceed to G3.

Step 5: Gate G3 — Simplify?

Show progress:

Implementing: execute -> SIMPLIFY -> review-impl -> [ship]
                         ^^^^^^^^

Preference check: Read pipeline.simplification using the two-tier lookup chain (see ${CLAUDE_PLUGIN_ROOT}/skills/arn-code-ensure-config/references/preferences-schema.md):

1. Read .arness/workflow.local.yaml — if the file exists and pipeline.simplification is present, use that value and note source.
2. If not found, read ~/.arness/workflow-preferences.yaml — if the file exists and pipeline.simplification is present, use that value and note source.
3. If neither found or key is absent, treat as null (first encounter).

Branch on the resolved value:

• If always: Show status line: "Preference: running simplification pass ([source])". Auto-proceed to Skill: arn-code:arn-code-simplify. After simplification completes, proceed to G4.

• If skip: Show status line: "Preference: skipping simplification ([source])". Auto-proceed to G4.

• If ask: Present the gate below. Do NOT show the "remember this?" follow-up afterward.

• If null (or invalid value): Present the gate below. After the user answers, show the "remember this?" follow-up (see below).

Gate (shown when value is ask, null, or invalid):

Ask (using AskUserQuestion):

"Execution complete. Simplify the implementation before review?"

Options:

1. Yes (Recommended for 3+ phases) — Review for reuse opportunities, quality issues, and efficiency improvements
2. Skip — Proceed without simplification

If Yes: Skill: arn-code:arn-code-simplify If Skip: Proceed to G4.

Follow-up (only when preference was null): After the user answers the gate, ask:

Ask (using AskUserQuestion):

"Should Arness remember this choice for future sessions?"

Options:

1. Yes, always [chosen action] (saves to preferences)
2. No, ask me each time

If Yes: Write the chosen value (always or skip) to ~/.arness/workflow-preferences.yaml under pipeline.simplification. Create ~/.arness/ directory and file if they do not exist. If the file already exists, read it first, add or update the key under pipeline:, and write back preserving all existing keys. If No: Write ask to ~/.arness/workflow-preferences.yaml under pipeline.simplification (same write logic).

Step 6: Gate G4 — Review Implementation?

Show progress:

Implementing: execute -> simplify -> REVIEW-IMPL -> [ship]
                                     ^^^^^^^^^^^

Preference check: Read `p