/arn-code-batch-simplify

name: arn-code-batch-simplify
description: >-
  This skill should be used when the user says "batch simplify", "cross-feature simplify",
  "batch simplification", "simplify all features", "cross-feature quality pass",
  "batch code cleanup", "consolidate across features", "deduplicate across features",
  "cleanup after batch merge", "cross-feature deduplication",
  "arness batch simplify", "arn-code-batch-simplify", "simplify merged features",
  "post-merge simplify", "find cross-feature duplication", or wants to run a
  post-merge quality pass that finds duplication and consolidation opportunities
  across independently implemented features. This requires merged features in
  .arness/plans/ — run arn-code-batch-merge first if none are merged.
version: 1.0.0

Arness Batch Simplify

Post-merge cross-feature quality pass that finds duplication and consolidation opportunities across independently implemented features. Uses the same 3-reviewer pattern as regular simplify but with cross-feature context so reviewers can identify duplicated utilities, inconsistent patterns, and shared logic that emerged from parallel development.

This is an execution skill. It runs in normal conversation (NOT plan mode).

Pipeline position:

arn-code-batch-merge -> **arn-code-batch-simplify** -> (optional: review-implementation -> document-project -> ship)

Prerequisites

If no `## Arness` section exists in the project's CLAUDE.md, inform the user: "Arness is not configured for this project yet. Run `/arn-implementing` to get started — it will set everything up automatically." Do not proceed without it.

Workflow

Step 0: Ensure Configuration

Read `${CLAUDE_PLUGIN_ROOT}/skills/arn-code-ensure-config/references/step-0-fast-path.md` and follow its instructions. Extract from `## Arness`:

• **Plans directory** (default: `.arness/plans`)
• **Code patterns** path (default: `.arness`)
• **Template path** (default: `.arness/templates`)

Hold these values for the remainder of the workflow.

---

Step 1: Load Pattern Documentation

Load pattern documentation from the code patterns directory:

1. `code-patterns.md` (required) 2. `testing-patterns.md` (required) 3. `architecture.md` (required) 4. `ui-patterns.md` (if it exists) 5. `security-patterns.md` (if it exists)

If any required pattern doc is missing, invoke the `arn-code-codebase-analyzer` agent to generate fresh analysis. If the analyzer is unavailable, suggest running `/arn-implementing` to get started.

Hold all loaded pattern documentation for use throughout the workflow.

---

Step 2: Collect Batch Scope

Scan the plans directory for `CHANGE_RECORD.json` files across all feature subdirectories:

1. For each `CHANGE_RECORD.json` found, check:

• `commitHash` is populated (feature was committed)
• The feature has been merged — check `gh pr view` if `nextSteps` contains a PR URL, or verify the feature branch was merged into main via `git branch --merged main`

2. For each merged feature's `CHANGE_RECORD.json`, collect:

• `filesModified` — files that were changed
• `filesCreated` — files that were added
• `projectName` — the feature name
• `ceremonyTier` — the ceremony level used
• `changePath` — path to the feature's plan directory

3. Build the **unified file list**: union of all `filesModified` + `filesCreated` across all merged features, deduplicated. Exclude files that no longer exist on disk (verify with `test -f`).

4. Build the **overlap map**: for each file that appears in 2+ features, record which features touch it. These are priority review targets.

**Exit conditions:**

• If zero merged features found: inform the user "No recently merged batch features found. Run `/arn-code-batch-merge` first." and exit.
• If the unified file list is empty: inform the user "No files to review — all features were merged but produced no file changes." and exit.

---

Step 3: Present Scope

Display the batch scope summary:

Cross-Feature Simplification Scope:

| Feature | Tier | Files |
|---------|------|-------|
| F-003 Auth | thorough | 12 |
| F-005 API | standard | 5 |
| F-008 Settings | thorough | 8 |

Total unique files: [N] (across [M] features)
Files touched by 2+ features: [K] (priority review)

Ask (using `AskUserQuestion`): **"Proceed with cross-feature simplification?"**

1. "Yes" (Recommended) 2. "Skip" — exit

If the user selects "Skip", exit gracefully.

---

Step 4: Dispatch Parallel Reviewers

Read `${CLAUDE_PLUGIN_ROOT}/skills/arn-code-batch-simplify/references/cross-feature-prompts.md` for the extended reviewer prompt templates.

Build the `{cross_feature_context}` block from the data collected in Step 2 — listing each feature's name, its files, and its change record path.

Dispatch three Agent tool calls **in a single message** so they run in parallel. Each call passes the model from `.arness/agent-models/code.md` (look up `arn-code-simplify-reviewer`) as the `model` parameter (see `${CLAUDE_PLUGIN_ROOT}/skills/arn-code-ensure-config/references/step-0-fast-path.md` "Dispatch convention" for fallback behavior). The three reviewers share the same synthetic name — apply the multi-agent rule by passing the looked-up value to each call independently. Note: `arn-code-simplify-reviewer` is shared with `arn-code-simplify` since both skills perform the same conceptual review work.

1. **Code Reuse Reviewer** — fill the cross-feature-prompts.md template with the file list, pattern documentation, and cross-feature context. Instruct the agent to focus on duplicated logic, missed utilities, and copy-paste patterns, with special attention to utilities created independently by different features.

2. **Code Quality Reviewer** — fill the template. Instruct the agent to focus on unnecessary complexity, dead code, unclear naming, and overly nested logic, with special attention to inconsistent approaches to the same pattern across features.

3. **Efficiency Reviewer** — fill the template. Instruct