batch-refactor

name	batch-refactor
description	Batch operations across files with confidence-based auto-apply. Use for renaming, search-replace, refactoring code, updating text/markdown, migrating terminology, and API migrations. Run `bun tools/refactor.ts --help` for detailed command reference.
allowed-tools	Bash, Read, Edit, Grep, Glob, AskUserQuestion

Batch Operations Skill

Quick start: Run bun vendor/bearly/tools/refactor.ts --help for command reference and examples.

Use this skill when the user wants to make changes across multiple files:

• Code refactoring: rename functions, variables, types
• Text/markdown updates: change terminology, update docs
• File operations: batch rename files with import path updates
• Terminology migrations: widget→gadget, vault→repo
• API migrations: old API patterns → new API patterns (LLM-powered)

Trigger phrases:

• "rename X to Y everywhere"
• "change all X to Y"
• "refactor X across the codebase"
• "batch replace"
• "update terminology"
• "migrate from X to Y"
• "rename function/variable everywhere"
• "change wording in all files"
• "migrate API" / "update API usage"
• "change how we call X"
• "update all uses of X to new pattern"
• "convert old pattern to new pattern"

---

Why Use Batch Refactor (Not Manual Edit)

⛔ NEVER use these for batch changes: sed, awk, perl, python -c, or manual Edit loops. These tools lack checksums, miss edge cases, and can corrupt files. See "Tips & Tricks → STOP: Manual Edit Tools" below.

ALWAYS use this tool instead of manual editing when:

Situation	Manual Edits	Batch Refactor
Rename a function used in 47 files	47 separate Edit calls	1 command
Rename parameter in destructuring patterns	Miss edge cases	Catches all patterns
Update terminology across codebase	Hours of work	Minutes
Rename file + update all imports	Break builds	Atomic, safe

Example: Why Manual Editing Fails

Task: Rename createWidget to createGadget

Manual approach (WRONG):

# You'd miss these patterns:
const { createWidget } = api          # destructuring
const init = createWidget             # assignment
type Factory = typeof createWidget    # type reference
async ({ createWidget }: Deps) => {}  # parameter destructuring

Batch refactor approach (CORRECT):

bun tools/refactor.ts rename.batch --pattern '/^createWidget$/' --replace createGadget --output edits.json
bun tools/refactor.ts editset.apply edits.json
# Finds ALL 127 references including destructuring, types, re-exports

Regex Patterns — Case Handling Is Explicit

CRITICAL: all --pattern and --from arguments must be regex literals in the form /pattern/flags.

This is a forcing function: plain strings hide a decision about case-sensitivity, and the wrong default silently corrupts camelCase identifiers. The regex form makes you choose:

Use case	Flag	Behavior
Code identifier rename	no /i	exact match, literal replacement — preserves the exact casing you typed
Prose terminology migration	/i	case-insensitive match, case-preserving replacement (widget→Gadget, WIDGET→GADGET)

# Code rename — case-sensitive, literal. Use for identifiers like screenRect, useBoxRect.
bun tools/refactor.ts pattern.replace --pattern '/screenRect/' --replace 'scrollRect'
bun tools/refactor.ts rename.batch --pattern '/^useContentRect$/' --replace 'useBoxRect'
bun tools/refactor.ts migrate --from '/contentRect/' --to 'boxRect' --dry-run

# Prose migration — case-insensitive, case-preserving. Use for English words.
bun tools/refactor.ts pattern.replace --pattern '/widget/i' --replace 'gadget'
# widget → gadget, Widget → Gadget, WIDGET → GADGET

# Word boundaries are explicit (\b), never implicit.
bun tools/refactor.ts pattern.replace --pattern '/\buseLayout\b/' --replace 'useBoxRect'

Why regex-first: every --pattern invocation becomes a moment where you look at the flags and consciously pick. Without this, you write --pattern screenRect and the tool silently downcases your replacement to scrollrect. The extra characters (/ and optional /i) are a small cost for eliminating a whole class of bugs.

The g flag is implicit (always multi-match within a file).

Quick Reference: When to Use Each Command

You want to...	Command	Example
Rename TypeScript function/variable	rename.batch	--pattern '/^createWidget$/' --replace createGadget
Rename TypeScript type/interface	rename.batch	--pattern '/^WidgetConfig$/' --replace GadgetConfig
Rename files	file.rename	--pattern widget --replace repo --glob "**/*.ts"
Update text in markdown	pattern.replace --backend ripgrep	--pattern '/widget/i' --replace repo --glob "**/*.md"
Full terminology migration	migrate	--from '/widget/i' --to repo
API migration (complex patterns)	pattern.migrate	--patterns "oldApi()" --prompt "migrate to newApi"

---

Comprehensive Migration Workflow

For large terminology migrations (e.g., "rename widget to repo"), follow this phased approach:

Phase 1: Conflict Analysis (BEFORE any changes)

CRITICAL: Analyze ALL conflicts before making ANY changes.

# Run from the batch plugin directory

# 1. Check file name conflicts
bun tools/refactor.ts file.rename --pattern widget --replace repo --glob "**/*.ts" --check-conflicts

# 2. Check symbol conflicts
bun tools/refactor.ts rename.batch --pattern '/widget/i' --replace repo --check-conflicts

# 3. Check for existing targets manually
ls **/repo*.ts 2>/dev/null || echo "No existing repo files"

For each conflict, document resolution:

Conflict	Resolution
widget.ts → repo.ts (exists)	Merge and delete
createWidget → createRepo (exists)	Update references, keep new

Never use --skip without explicit user approval.

Phase 2: File Renames

Rename files FIRST (before symbol renames) because:

• Import paths need to be valid for ts-morph to work
• File renames update import paths automatically

# Create file rename proposal
bun tools/refactor.ts file.rename --pattern widget --replace repo \
  --glob "**/*.{ts,tsx}" \
  --output file-editset.json

# Preview
bun tools/refactor.ts file.apply file-editset.json --dry-run

# Apply
bun tools/refactor.ts file.apply file-editset.json

Phase 3: Symbol Renames (TypeScript)

After files are renamed, rename symbols:

# Create symbol rename proposal
bun tools/refactor.ts rename.batch --pattern '/widget/i' --replace repo \
  --output symbol-editset.json

# Preview
bun tools/refactor.ts editset.apply symbol-editset.json --dry-run

# Apply
bun tools/refactor.ts editset.apply symbol-editset.json

Phase 4: Text/Comment Renames

Rename remaining mentions in comments, strings, markdown:

# TypeScript comments and strings
bun tools/refactor.ts pattern.replace --pattern '/widget/i' --replace repo \
  --glob "**/*.{ts,tsx}" \
  --backend ripgrep \
  --output text-editset.json

# Markdown documentation
bun tools/refactor.ts pattern.replace --pattern '/widget/i' --replace repo \
  --glob "**/*.md" \
  --backend ripgrep \
  --output docs-editset.json

# Preview and apply each
bun tools/refactor.ts editset.apply text-editset.json --dry-run
bun tools/refactor.ts editset.apply text-editset.json

Phase 5: Vendor Submodules

For changes in git submodules:

# For each vendor submodule with matches
cd vendor/<submodule>

# Run the same workflow (conflicts, files, symbols, text)
bun ../tools/plugins/batch/tools/refactor.ts rename.batch \
  --pattern '/widget/i' --replace repo --check-conflicts

# After applying
git add -A
git commit -m "refactor: rename widget → repo"
git push

# Return to main repo
cd ../..
git add vendor/<submodule>
git commit -m "chore(vendor): update <submodule> with repo terminology"

Phase 6: Verification

# Check for remaining mentions
grep -ri widget . --include="*.ts" --include="*.tsx" | grep -v node_modules | wc -l

# Type check
bun tsc --noEmit

# Lint and fix
bun fix

# Run tests
bun run test:all

---

Tool Selection

What you're changing	File Type	Backend	Command
File names	any	file-ops	file.rename
TypeScript/JS identifiers	.ts, .tsx, .js, .jsx	ts-morph	rename.batch
API patterns (complex)	.ts, .tsx	LLM	pattern.migrate
Go, Rust, Python structural patterns	.go, .rs, .py	ast-grep	pattern.replace
JSON/YAML values	.json, .yaml	ast-grep	pattern.replace
Text/markdown/comments	.md, .txt, any	ripgrep	pattern.replace
Wiki links only	.md	wikilink	wikilink.rename
package.json paths	package.json	package-json	package.rename
tsconfig.json paths	tsconfig*.json	tsconfig-json	tsconfig.rename

file.rename auto-detects file type and updates references:

• .ts/.tsx/.js/.jsx → updates import paths
• .md/.markdown/.mdx → updates [[wikilinks]] (Obsidian, Foam, etc.)
• package.json → updates exports, main, types, bin paths
• tsconfig.json → updates paths mappings, includes, references

CRITICAL for TypeScript: Always use ts-morph (via rename.batch) for identifiers. It handles destructuring, arrow function params, and nested scopes that text-based tools miss.

Dependencies:

• ts-morph: bundled (no external CLI)
• ast-grep: requires sg CLI (brew install ast-grep)
• ripgrep: requires rg CLI (usually pre-installed)

---

CLI Reference

File Operations

Command	Purpose
file.find --pattern <p> --replace <r> [--glob]	Find files to rename
file.rename --pattern <p> --replace <r> [--glob] [--output] [--check-conflicts]	Create file rename proposal
file.verify <file>	Verify file editset can be applied
file.apply <file> [--dry-run]	Apply file renames

TypeScript/JavaScript (ts-morph)

Command	Purpose
symbol.at <file> <line> [col]	Find symbol at location
refs.list <symbolKey>	List all references to a symbol
symbols.find --pattern <regex>	Find symbols matching pattern
rename.propose <key> <new>	Single symbol rename proposal
rename.batch --pattern <p> --replace <r> [--check-conflicts]	Batch rename proposal

Multi-Language (ast-grep/ripgrep)

Command	Purpose
pattern.find --pattern <p> [--glob] [--backend]	Find structural patterns
pattern.replace --pattern <p> --replace <r> [--glob] [--backend]	Pattern replace proposal
pattern.migrate --patterns <p1,p2> --prompt <text> [--glob]	LLM-powered API migration
backends.list	List available backends

Editset Operations

Command	Purpose
editset.select <file> --include/--exclude	Filter editset refs
editset.verify <file>	Check editset can be applied
editset.apply <file> [--dry-run]	Apply with checksum verification

Package.json Operations

Command	Purpose
package.find --target <file>	Find package.json refs to a file
package.rename --old <path> --new <path>	Update paths when file renamed
package.broken	Find broken paths in package.json

TSConfig.json Operations

Command	Purpose
tsconfig.find --target <file>	Find tsconfig.json refs to a file
tsconfig.rename --old <path> --new <path>	Update paths when file renamed

---

Concrete Examples by Operation Type

Example 1: Batch File Rename

Scenario: Rename all files containing "user-service" to "account-service"

# 1. Find files that would be renamed
bun tools/refactor.ts file.find --pattern "user-service" --replace "account-service" --glob "**/*.ts"

# 2. Check for conflicts (target files already exist?)
bun tools/refactor.ts file.rename --pattern "user-service" --replace "account-service" \
  --glob "**/*.ts" --check-conflicts

# 3. Create editset
bun tools/refactor.ts file.rename --pattern "user-service" --replace "account-service" \
  --glob "**/*.ts" --output file-renames.json

# 4. Preview (dry run)
bun tools/refactor.ts file.apply file-renames.json --dry-run

# 5. Apply
bun tools/refactor.ts file.apply file-renames.json

Result:

• src/user-service.ts → src/account-service.ts
• src/testing/mock-user-service.ts → src/testing/mock-account-service.ts
• UserServiceConfig.ts → AccountServiceConfig.ts (case preserved)

---

Example 2: Import Path Updates (after file renames)

Scenario: Update all imports that reference renamed files

# After renaming user-service.ts → account-service.ts, update imports:
bun tools/refactor.ts pattern.replace \
  --pattern "user-service" \
  --replace "account-service" \
  --glob "**/*.ts" \
  --backend ripgrep \
  --output import-updates.json

bun tools/refactor.ts editset.apply import-updates.json --dry-run
bun tools/refactor.ts editset.apply import-updates.json

Before:

import { createUser } from "./user-service"
import { UserService } from "../services/user-service"

After:

import { createUser } from "./account-service"
import { UserService } from "../services/account-service"

---

Example 3: TypeScript Symbol Rename (ts-morph)

Scenario: Rename function createWidget to createGadget across codebase

# 1. Check for conflicts (does createGadget already exist?)
bun tools/refactor.ts rename.batch --pattern "createWidget" --replace "createGadget" --check-conflicts

# 2. Create editset
bun tools/refactor.ts rename.batch --pattern "createWidget" --replace "createGadget" \
  --output symbol-renames.json

# 3. Preview
bun tools/refactor.ts editset.apply symbol-renames.json --dry-run

# 4. Apply
bun tools/refactor.ts editset.apply symbol-renames.json

Handles correctly:

// Function declaration
export function createWidget(config: Config) { }  → createGadget

// Arrow function
const createWidget = (opts) => { }  → createGadget

// Destructuring
const { createWidget } = api  → createGadget

// Parameter
function init({ createWidget }: Deps) { }  → createGadget

// Type reference
type Factory = typeof createWidget  → createGadget

---

Example 4: Type/Interface Rename

Scenario: Rename ApiClient to HttpClient across codebase

# Check conflicts
bun tools/refactor.ts rename.batch --pattern "ApiClient" --replace "HttpClient" --check-conflicts

# Create and apply
bun tools/refactor.ts rename.batch --pattern "ApiClient" --replace "HttpClient" \
  --output type-renames.json
bun tools/refactor.ts editset.apply type-renames.json

Handles correctly:

// Interface definition
export interface ApiClient { }  → HttpClient

// Type alias
type Client = ApiClient  → HttpClient

// Variable type annotation
const client: ApiClient = ...  → HttpClient

// Generic constraint
function fetch<T extends ApiClient>()  → HttpClient

// Import
import type { ApiClient } from "./api"  → HttpClient

---

Example 5: Text/Comment/String Replace (ripgrep)

Scenario: Update documentation and comments from "widget" to "gadget"

# Markdown docs
bun tools/refactor.ts pattern.replace \
  --pattern "widget" \
  --replace "gadget" \
  --glob "**/*.md" \
  --backend ripgrep \
  --output docs-updates.json

# TypeScript comments and strings
bun tools/refactor.ts pattern.replace \
  --pattern "widget" \
  --replace "gadget" \
  --glob "**/*.ts" \
  --backend ripgrep \
  --output comment-updates.json

# Preview and apply
bun tools/refactor.ts editset.apply docs-updates.json --dry-run
bun tools/refactor.ts editset.apply docs-updates.json

Updates:

// This creates a new widget  → gadget
const msg = "Widget not found"  → "Gadget not found"
/** @description Widget factory */  → Gadget factory

# Widget Guide → Gadget Guide

Create a widget with... → Create a gadget with...

---

Example 6: Structural Pattern Replace (ast-grep)

Scenario: Migrate Go logging from fmt.Println to log.Info

bun tools/refactor.ts pattern.replace \
  --pattern 'fmt.Println($MSG)' \
  --replace 'log.Info($MSG)' \
  --glob "**/*.go" \
  --backend ast-grep \
  --output go-logging.json

bun tools/refactor.ts editset.apply go-logging.json

Before:

fmt.Println("Starting server")
fmt.Println(err.Error())

After:

log.Info("Starting server")
log.Info(err.Error())

---

Example 7: Complete Terminology Migration

Scenario: Migrate entire codebase from "user" terminology to "account"

# Phase 1: Conflict Analysis
bun tools/refactor.ts file.rename --pattern "user" --replace "account" --check-conflicts
bun tools/refactor.ts rename.batch --pattern "user" --replace "account" --check-conflicts

# Phase 2: File Renames (FIRST)
bun tools/refactor.ts file.rename --pattern "user" --replace "account" \
  --glob "**/*.ts" --output phase2-files.json
bun tools/refactor.ts file.apply phase2-files.json

# Phase 3: Symbol Renames
bun tools/refactor.ts rename.batch --pattern "user" --replace "account" \
  --output phase3-symbols.json
bun tools/refactor.ts editset.apply phase3-symbols.json

# Phase 4: Text/Comments
bun tools/refactor.ts pattern.replace --pattern "user" --replace "account" \
  --glob "**/*.ts" --backend ripgrep --output phase4-text.json
bun tools/refactor.ts editset.apply phase4-text.json

# Phase 5: Documentation
bun tools/refactor.ts pattern.replace --pattern "user" --replace "account" \
  --glob "**/*.md" --backend ripgrep --output phase5-docs.json
bun tools/refactor.ts editset.apply phase5-docs.json

# Phase 6: Verify
grep -ri user . --include="*.ts" | wc -l  # Should be 0
bun tsc --noEmit
bun fix
bun run test:all

---

Example 8: Selective Rename with Filtering

Scenario: Rename only specific occurrences, not all

# Create full editset
bun tools/refactor.ts rename.batch --pattern "config" --replace "options" \
  --output full-editset.json

# Filter to only certain files
bun tools/refactor.ts editset.select full-editset.json \
  --include "src/core/**" \
  --exclude "src/core/legacy/**" \
  --output filtered-editset.json

# Apply filtered set
bun tools/refactor.ts editset.apply filtered-editset.json

---

Case Preservation

The tool preserves case during renames:

Original	Pattern	Replacement	Result
widget	widget	repo	repo
Repo	widget	repo	Repo
REPO	widget	repo	REPO
widgetPath	widget	repo	repoPath
WidgetConfig.ts	widget	repo	GadgetConfig.ts

---

Conflict Resolution

Never skip conflicts without understanding them.

File Conflicts

Conflict Type	Resolution Strategy
Target exists (duplicate)	Merge content, delete source
Target exists (different)	Rename to avoid collision
Same path (no-op)	Skip (no change needed)

Symbol Conflicts

Conflict Type	Resolution Strategy
Target name exists	Check if same symbol (safe to merge) or different (needs rename)
Multiple symbols same name	May be scoped (function-local vs module) - often safe

Process:

1. Run --check-conflicts first
2. Document each conflict and its resolution
3. Get user approval on resolution strategy
4. Execute with explicit handling (no blind --skip)

---

Safety Checks

Before making batch changes:

git rev-parse --is-inside-work-tree 2>/dev/null
git status --porcelain

Situation	Action
Git repo, clean working tree	✅ Proceed
Git repo, uncommitted changes	⚠️ Ask user to commit first
Not a git repo	⚠️ Warn: no undo available

---

Context Gathering

Before making changes, gather project context:

1. Read CLAUDE.md - look for:

   • Mentioned migrations or refactoring plans
   • ADR references
   • Terminology notes

2. Check for migration scripts (optional):

   • scripts/check-migration.ts or similar
   • May have ALLOWED_PATTERNS for exclusions

3. Understand scope:

   grep -ri <pattern> . --include="*.ts" | wc -l  # Total mentions
   find . -name "*<pattern>*" -not -path "./node_modules/*"  # File names
   

---

Confidence Philosophy

Be aggressive. Tests catch mistakes.

Context	Confidence
Our code (const widgetRoot)	HIGH
Our compound identifier (widgetHelper)	HIGH
Our error message ("widget not found")	HIGH
External reference ("Obsidian widget")	LOW - may need to keep
URL/path (widget.example.com)	LOW

Default to HIGH unless clearly external.

---

Why ast-grep Fails for TypeScript Identifiers

ast-grep misses TypeScript-specific patterns:

// ast-grep renames this ✓
const widgetDir = "/path"

// But MISSES these ✗
interface TestEnv { widgetDir: string }  // property definition
({ widgetDir }) => { ... }               // destructuring

Rule: If it shows up in "Find All References" in your IDE, use ts-morph.

---

Example: Complete Migration

User request: "rename widget to repo everywhere"

Claude's plan:

1. Analyze scope

   grep -ri widget . --include="*.ts" | wc -l
   find . -name "*widget*" -not -path "./node_modules/*"
   

2. Check ALL conflicts

   # File conflicts
   bun tools/refactor.ts file.rename --pattern widget --replace repo --check-conflicts
   
   # Symbol conflicts
   bun tools/refactor.ts rename.batch --pattern '/widget/i' --replace repo --check-conflicts
   

3. Document conflict resolutions (ask user if unclear)

4. Execute in phases:

   • Phase 2: File renames
   • Phase 3: Symbol renames
   • Phase 4: Text/comment renames
   • Phase 5: Vendor submodules

5. Verify:

   grep -ri widget . --include="*.ts" | wc -l  # Should be 0 (or only allowed)
   bun tsc --noEmit
   bun fix
   bun run test:all
   

---

Important Rules

1. Check conflicts FIRST - never blind rename
2. File renames BEFORE symbol renames - import paths must be valid
3. Use editset workflow for TypeScript identifiers
4. Always run tsc after batch changes
5. Preview with --dry-run before applying
6. Trust checksums - editset won't apply to modified files
7. Vendor submodules - commit and push separately, then update reference
8. Be aggressive - apply all matches, let tests catch mistakes

---

LLM Patch Workflow

Editsets now include enriched context fields that allow an LLM to review and selectively modify replacements before applying. This enables intelligent, context-aware refactoring decisions.

Enriched Reference Fields

Each reference in an editset includes:

Field	Type	Description
kind	"call" | "decl" | "type" | "string" | "comment"	What kind of reference this is
scope	string | null	Enclosing function/class name, or null for module-level
ctx	string[]	Array of context lines with ► marker on the matching line
replace	string | null	null to skip this reference, string for custom replacement

Workflow

# Run from the batch plugin directory

# 1. Generate editset with enriched context
bun tools/refactor.ts rename.batch --pattern '/widget/i' --replace repo -o editset.json

# 2. LLM reviews the editset and patches specific references
#    - Set replace to null to skip a reference
#    - Set replace to a custom string for non-standard replacement
bun tools/refactor.ts editset.patch editset.json <<'EOF'
{ "b2c3": "Repository", "c3d4": null }
EOF

# 3. Apply the patched editset
bun tools/refactor.ts editset.apply editset.json

Example: Selective Replacement

Given an editset with these references:

{
  "refs": [
    {
      "id": "a1b2",
      "kind": "decl",
      "scope": "createWidget",
      "replace": "repo"
    },
    { "id": "b2c3", "kind": "type", "scope": null, "replace": "repo" },
    { "id": "c3d4", "kind": "comment", "scope": null, "replace": "repo" }
  ]
}

An LLM might decide:

• Keep a1b2 as-is (standard replacement)
• Change b2c3 to "Repository" (capitalize for type name)
• Set c3d4 to null (skip comment, it refers to external Obsidian widget)

bun tools/refactor.ts editset.patch editset.json <<'EOF'
{ "b2c3": "Repository", "c3d4": null }
EOF

Context Lines

The ctx field shows surrounding lines with the match marked:

{
  "ctx": ["  // Create a new widget for the user", "► const vault = createVault(config)", "  return widget"]
}

This helps LLMs understand whether a reference is:

• Internal code (safe to rename)
• External reference (may need to preserve)
• Documentation (may need different wording)

---

Migrate Command

The migrate command orchestrates a full terminology migration in phases:

# Run from the batch plugin directory

# Preview what would be migrated
bun tools/refactor.ts migrate --from '/widget/i' --to repo --dry-run

# Run migration (creates editsets in .editsets/ directory)
bun tools/refactor.ts migrate --from '/widget/i' --to repo

# Custom output directory
bun tools/refactor.ts migrate --from '/widget/i' --to repo --output ./my-editsets

# Custom file glob
bun tools/refactor.ts migrate --from '/widget/i' --to repo --glob "**/*.{ts,tsx,md}"

What Migrate Does

Phase	Description	Output File
1. File renames	Rename files containing pattern	01-file-renames.json
2. Symbol renames	TypeScript identifiers via ts-morph	02-symbol-renames.json
3. Text patterns	Comments, strings via ripgrep	03-text-patterns.json

After running, review each editset and apply:

# Review and apply each phase
bun tools/refactor.ts file.apply .editsets/01-file-renames.json --dry-run
bun tools/refactor.ts file.apply .editsets/01-file-renames.json

bun tools/refactor.ts editset.apply .editsets/02-symbol-renames.json --dry-run
bun tools/refactor.ts editset.apply .editsets/02-symbol-renames.json

bun tools/refactor.ts editset.apply .editsets/03-text-patterns.json --dry-run
bun tools/refactor.ts editset.apply .editsets/03-text-patterns.json

Migrate Command Flags

Flag	Description	Default
--from <pattern>	Pattern to match (required)	-
--to <replacement>	Replacement string (required)	-
--glob <glob>	File glob filter	**/*.{ts,tsx}
--dry-run	Preview without creating editsets	false
--output <dir>	Output directory for editsets	.editsets

---

LLM-Powered API Migration (pattern.migrate)

For complex API migrations where simple find/replace isn't enough, use pattern.migrate. This command:

1. Searches for patterns using ripgrep
2. Gathers context around each match
3. Sends to LLM in one call to determine correct replacements
4. Generates editset for review and application

When to Use pattern.migrate

Use pattern.migrate instead of pattern.replace when:

• Transformations require understanding context (e.g., adding await, changing variable names)
• Multiple related patterns need coordinated changes
• Replacements involve value mapping (e.g., ANSI codes → key names)
• The old and new patterns have different structures (destructuring → single variable)

Example: Test Framework API Migration

# OLD API:
# const { lastFrame, stdin } = render(<App />)
# expect(stripAnsi(lastFrame())).toContain('Hello')
# stdin.write('\x1b[A')

# NEW API:
# const app = render(<App />)
# expect(app.text).toContain('Hello')
# await app.press('ArrowUp')

bun tools/refactor.ts pattern.migrate \
  --patterns "lastFrame(),stdin.write,= render(" \
  --glob "**/*.test.tsx" \
  --prompt "Migrate old render() API to new App API:
    - const { lastFrame, stdin } = render(...) → const app = render(...)
    - lastFrame() → app.ansi
    - stripAnsi(lastFrame()) → app.text
    - stdin.write('\\x1b[A') → await app.press('ArrowUp')
    - stdin.write('\\x1b[B') → await app.press('ArrowDown')" \
  --output /tmp/migrate.json

# Review
jq '.refs[:5]' /tmp/migrate.json

# Apply
bun tools/refactor.ts editset.apply /tmp/migrate.json

Command Flags

Flag	Description	Default
--patterns <p1,p2,...>	Comma-separated search patterns (required)	-
--prompt <text>	Migration instructions for LLM (required)	-
--glob <glob>	File filter	**/*.{ts,tsx}
--output <file>	Editset output file	/tmp/migrate.json
--model <model>	Override LLM model	best available
--dry-run	Preview prompt without calling LLM	false

Workflow

# 1. Dry run - see what would be sent to LLM
bun tools/refactor.ts pattern.migrate \
  --patterns "oldPattern" \
  --glob "**/*.ts" \
  --prompt "Migrate to new pattern" \
  --dry-run

# 2. Run migration
bun tools/refactor.ts pattern.migrate \
  --patterns "oldPattern" \
  --glob "**/*.ts" \
  --prompt "Migrate to new pattern" \
  --output /tmp/migrate.json

# 3. Review editset
jq '.refs | length' /tmp/migrate.json        # Count changes
jq '.refs[:3]' /tmp/migrate.json             # Preview first 3

# 4. Apply
bun tools/refactor.ts editset.apply /tmp/migrate.json

# 5. Verify
bun tsc --noEmit && bun run test:fast

Writing Good Migration Prompts

The LLM sees each match with ~3 lines of context. Write prompts that:

1. List all transformation rules clearly with before → after
2. Include edge cases (e.g., what to do with stripAnsi() wrappers)
3. Specify async handling if needed (when to add await)
4. Include value mappings if applicable (ANSI codes to key names)

# Good prompt example:
--prompt "Migrate test API:
  - const { lastFrame, stdin } = render(...) → const app = render(...)
  - lastFrame() → app.ansi
  - stripAnsi(lastFrame()) → app.text (remove stripAnsi wrapper)
  - stdin.write('x') → await app.press('x')
  - stdin.write('\\x1b[A') → await app.press('ArrowUp')
  - stdin.write('\\x1b[B') → await app.press('ArrowDown')
  - stdin.write('\\x1b[C') → await app.press('ArrowRight')
  - stdin.write('\\x1b[D') → await app.press('ArrowLeft')
  - stdin.write('\\r') → await app.press('Enter')"

---

Enriched Editset JSON Format

When an LLM reviews an editset, it sees enriched context for each reference:

{
  "id": "rename-widget-to-repo-1706123456789",
  "operation": "rename",
  "from": "widget",
  "to": "repo",
  "refs": [
    {
      "refId": "a1b2c3d4",
      "file": "src/storage.ts",
      "line": 45,
      "range": [45, 12, 45, 17],
      "kind": "call",
      "scope": "initStorage",
      "ctx": ["  function initStorage() {", "► const root = createVault(config);", "  return root;"],
      "replace": "repo",
      "preview": "const root = createWidget(config);",
      "checksum": "abc123...",
      "selected": true
    },
    {
      "refId": "b2c3d4e5",
      "file": "src/errors.ts",
      "line": 12,
      "range": [12, 25, 12, 30],
      "kind": "string",
      "scope": "errorHandler",
      "ctx": ["► throw new Error(\"vault not found\");"],
      "replace": "repo",
      "preview": "throw new Error(\"widget not found\");",
      "checksum": "def456...",
      "selected": true
    }
  ],
  "edits": [
    /* ... byte-level edits */
  ],
  "createdAt": "2024-01-24T12:00:00.000Z"
}

Field Reference

Field	Type	Description
refId	string	Stable identifier for this reference
kind	"call" | "decl" | "type" | "string" | "comment"	Semantic kind
scope	string | null	Enclosing function/class, or null for module-level
ctx	string[]	Context lines with ► marker on match line
replace	string | null	Replacement text, or null to skip
line	number	1-indexed line number
range	[number, number, number, number]	[startLine, startCol, endLine, endCol]

---

editset.patch Command

Apply LLM-generated patches to editsets via stdin (heredoc):

# Minimal patch format: refId → replacement or null
bun tools/refactor.ts editset.patch editset.json <<'EOF'
{
  "b2c3d4e5": "repository",
  "c3d4e5f6": null
}
EOF

# Or pipe from a file
cat my-patch.json | bun tools/refactor.ts editset.patch editset.json

# Output to different file
bun tools/refactor.ts editset.patch editset.json --output patched.json <<'EOF'
{ "b2c3": null }
EOF

Patch Format

The patch is a simple JSON object mapping refIds to actions:

{
  "refId1": "custom replacement", // Use this replacement instead of default
  "refId2": null // Skip this reference
  // refId3 not mentioned           // Apply with default replacement
}

Patch Value	Action
"string"	Use this replacement text
null	Skip this reference (don't apply)
(not in patch)	Apply with default to replacement

Full Editset Patch

You can also pass a full editset with modified replace fields:

{
  "refs": [
    { "refId": "a1b2", "replace": "Repository" },
    { "refId": "b2c3", "replace": null }
  ]
}

The patch command extracts refId and replace from each ref.

---

More Examples: Edge Cases Manual Editing Misses

Example 9: Destructuring Parameters (ts-morph REQUIRED)

Scenario: Rename widgetPath to repoPath — appears in destructuring patterns

Manual grep would find:

const widgetPath = "/path/to/widget" // ✓ obvious

But MISS these (ts-morph catches them):

// Destructuring in function parameter
export function init({ widgetPath, config }: Options) {
  return load(widgetPath)
}

// Nested destructuring
const {
  paths: { widgetPath },
} = config

// Arrow function parameter destructuring
const handler = ({ widgetPath }: Ctx) => widgetPath

// Object shorthand
return { widgetPath } // property AND value both renamed

Command:

bun tools/refactor.ts rename.batch --pattern '/^widgetPath$/' --replace repoPath --output edits.json
bun tools/refactor.ts editset.apply edits.json
# All 47 occurrences updated atomically

---

Example 10: Re-exports and Barrel Files (ts-morph REQUIRED)

Scenario: Rename Widget to Gadget — used in index.ts re-exports

Manual editing misses:

// src/index.ts - barrel file
export { Widget } from "./widget"
export type { Widget, WidgetConfig } from "./widget"

// src/components/index.ts - nested barrel
export * from "./Widget"
export { Widget as DefaultWidget } from "./Widget"

ts-morph finds ALL of these:

bun tools/refactor.ts rename.batch --pattern '/^Widget$/' --replace Gadget --output edits.json
# Found: 89 references across 23 files including all re-exports

---

Example 11: Type-Only Imports

Scenario: Rename UserService interface — used in type-only imports

Manual editing risks:

// Type-only import - easy to miss with grep
import type { UserService } from "./services"

// Inline type import
const fn = (service: import("./services").UserService) => {}

// Generic constraints
function process<T extends UserService>(svc: T) {}

ts-morph finds all patterns:

bun tools/refactor.ts rename.batch --pattern '/^UserService$/' --replace AccountService --check-conflicts
bun tools/refactor.ts rename.batch --pattern '/^UserService$/' --replace AccountService --output edits.json

---

Example 12: JSDoc References

Scenario: Rename parseConfig — referenced in JSDoc comments

/**
 * @see parseConfig for config format
 * @param {ReturnType<typeof parseConfig>} config
 */
function initApp(config) {}

ripgrep backend catches JSDoc:

bun tools/refactor.ts pattern.replace \
  --pattern '/^parseConfig$/' \
  --replace loadConfig \
  --glob "**/*.{ts,js}" \
  --backend ripgrep \
  --output jsdoc-updates.json

---

Example 13: Dynamic Imports

Scenario: Rename file user-api.ts to account-api.ts — dynamic imports exist

// Static import (caught by ts-morph file.rename)
import { getUser } from "./user-api"

// Dynamic import (caught by ripgrep pattern.replace)
const api = await import("./user-api")
const { handler } = await import(`./user-api`)

Two-step approach:

# 1. Rename file + static imports
bun tools/refactor.ts file.rename --pattern user-api --replace account-api --output files.json
bun tools/refactor.ts file.apply files.json

# 2. Catch dynamic imports
bun tools/refactor.ts pattern.replace \
  --pattern "user-api" \
  --replace "account-api" \
  --glob "**/*.ts" \
  --backend ripgrep \
  --output dynamic.json
bun tools/refactor.ts editset.apply dynamic.json

---

Example 14: Test Mocks and Fixtures

Scenario: Rename createWidget — but test mocks use it too

// src/widget.ts
export function createWidget() {}

// tests/widget.test.ts
vi.mock("../widget", () => ({
  createWidget: vi.fn(), // Mock uses same name
}))

// tests/fixtures/widget-fixture.ts
export const mockCreateWidget = () => {} // Compound identifier

ts-morph renames ALL including mocks:

bun tools/refactor.ts rename.batch --pattern '/^createWidget$/' --replace createGadget --output edits.json
# Found in: src/widget.ts, 12 test files, 3 fixture files

---

Example 15: Partial Word Match with Case Preservation

Scenario: Rename all widget occurrences — different casings exist

const widget = {} // lowercase
const Repo = {} // PascalCase
const REPO_PATH = "" // SCREAMING_CASE
const widgetConfig = {} // camelCase compound
class RepoManager {} // PascalCase compound
const REPO_OPTIONS = {} // SCREAMING compound

Automatic case preservation:

bun tools/refactor.ts rename.batch --pattern '/widget/i' --replace repo --output edits.json

Result:

const repo = {} // lowercase preserved
const Repo = {} // PascalCase preserved
const REPO_PATH = "" // SCREAMING_CASE preserved
const repoConfig = {} // camelCase compound
class RepoManager {} // PascalCase compound
const REPO_OPTIONS = {} // SCREAMING compound

---

Example 16: Multi-Package Monorepo

Scenario: Rename across multiple packages in a monorepo

packages/
  core/src/widget.ts
  cli/src/commands/widget.ts
  tui/src/views/widget-view.tsx
  storage/src/widget-loader.ts

Single command handles all:

bun tools/refactor.ts migrate --from '/widget/i' --to repo --glob "packages/**/*.{ts,tsx}"

# Creates editsets in .editsets/:
# - 01-file-renames.json (4 files)
# - 02-symbol-renames.json (234 symbols)
# - 03-text-patterns.json (89 text occurrences)

---

Example 17: Rollback Safety with Checksums

Scenario: Someone edited a file after you created the editset

# Create editset
bun tools/refactor.ts rename.batch --pattern '/^Widget$/' --replace Gadget --output edits.json

# ... time passes, teammate edits src/widget.ts ...

# Apply fails safely with drift detection
bun tools/refactor.ts editset.apply edits.json
# Error: Drift detected in src/widget.ts (checksum mismatch)
# Skipped: 3 edits in src/widget.ts
# Applied: 45 edits in other files

The editset NEVER corrupts files — if the file changed, it skips that file.

---

Decision Tree: Which Command to Use

Is this a terminology migration (file names + code + docs)?
├── YES → `migrate --from /X/ --to Y`
└── NO
    ├── Is this an API migration (complex pattern changes)?
    │   └── YES → `pattern.migrate --patterns X --prompt "..."` (LLM-powered)
    ├── Renaming files?
    │   └── YES → `file.rename --pattern X --replace Y`
    ├── Renaming TypeScript identifiers?
    │   └── YES → `rename.batch --pattern /X/ --replace Y`
    ├── Updating Go/Rust/Python structural patterns?
    │   └── YES → `pattern.replace --backend ast-grep`
    └── Updating text/markdown/comments?
        └── YES → `pattern.replace --backend ripgrep`

Use pattern.migrate when:

• Old → new patterns have different structures (not just name changes)
• Transformations need context awareness (adding await, changing variable scope)
• Multiple related patterns need coordinated changes
• Value mapping is required (e.g., escape codes → named keys)

---

Performance Comparison

Task	Manual Edits	Batch Refactor
Rename function (50 refs)	~50 Edit calls	2 commands
Rename file + imports	Risk broken build	Atomic update
Full terminology migration	Hours	Minutes
Rollback on error	Manual git restore	Automatic (checksums)

Rule of thumb: If you'd make more than 5 edits, use batch refactor

---

Tips & Tricks

⛔ STOP: Manual Edit Tools

IMMEDIATELY STOP AND THINK if you're about to use any of these:

Tool	What it does	Why you should stop
sed	Stream editing	batch-refactor does this better with checksums
awk	Pattern processing	batch-refactor handles this
perl -pe	Regex replacement	batch-refactor does this safely
python -c	Quick scripts	batch-refactor is purpose-built for this
Manual Edit tool in loop	Many small edits	batch-refactor does this atomically

Before using these, ask yourself:

1. Can batch-refactor do this? → Use pattern.replace or rename.batch
2. Is this a text pattern? → Use pattern.replace --backend ripgrep
3. Is this a TypeScript symbol? → Use rename.batch (ts-morph)
4. Is this a structural pattern? → Use pattern.replace --backend ast-grep

If batch-refactor CAN'T do what you need:

1. File a feature request as a bead: bd create --title "batch-refactor: support X" --type=task
2. Document the gap in the bead description
3. Only then use the manual tool as a workaround

The goal: Every manual edit is a signal that batch-refactor is missing a feature.

---

1. Store editsets in /tmp

Storing editsets outside the repo avoids cluttering your working directory and needing grep -v .editsets when verifying:

# Instead of:
bun tools/refactor.ts migrate --from '/widget/i' --to repo -o .editsets
rg -l widget -g "*.ts" | grep -v .editsets | wc -l  # Annoying

# Do this:
bun tools/refactor.ts migrate --from '/widget/i' --to repo -o /tmp/editsets
rg -l widget -g "*.ts" | wc -l  # Clean

2. Preview editset contents

Before applying, inspect what an editset will do:

# Quick look at the editset structure and refs
cat /tmp/editset.json | head -50

# See how many refs/edits
cat /tmp/editset.json | jq '{refs: .refs | length, edits: .edits | length}'

# Dry-run shows what would be applied
bun tools/refactor.ts editset.apply /tmp/editset.json --dry-run

3. Use rg directly for exploration

Before running batch operations, verify your patterns find what you expect:

# Find files containing pattern
rg -l "useRepo" -g "*.ts"

# Show matches with line numbers
rg -n "useRepo" -g "*.ts"

# Count matches
rg -c "widget" -g "*.ts" | head -20

# Show context around matches
rg -C 2 "createWidget" -g "*.ts"

4. Use rg for file discovery too

rg --files lists files matching globs, respecting .gitignore. One tool for everything:

# Instead of find (slow, doesn't respect .gitignore):
find . -name "*widget*" -not -path "./node_modules/*"

# Use rg --files with glob:
rg --files -g "*widget*"           # Files with "widget" in name
rg --files -g "*.ts" | head -10   # All .ts files
rg --files -g "*widget*.ts"        # .ts files with "widget" in name
rg --files packages/              # All files in packages/

5. Avoid slow shell loops

Shell loops with rg are slow. Use rg's built-in features instead:

# SLOW - shell loop overhead - DON'T DO THIS
rg -l "widget" | while read f; do
  echo "=== $f ==="
  rg -n "widget" "$f"
done

# FAST - single rg invocation
rg -n "widget" -g "*.ts"                    # Filename:line:match
rg --heading -n "widget" -g "*.ts"          # Group by filename
rg --vimgrep "widget" -g "*.ts"             # file:line:col:match

6. Verify glob patterns work

Test glob patterns with rg directly before using them in batch commands:

# Test the glob finds expected files
rg --files -g "**/*.ts" | head -10
rg --files -g "apps/**/*.tsx" | head -10

# Then use same glob in batch command
bun tools/refactor.ts pattern.replace --pattern '/widget/i' --replace 'gadget' --glob "apps/**/*.tsx" -o /tmp/edits.json

6. Check remaining mentions efficiently

After migration, verify zero remaining mentions:

# Fast count of remaining mentions
rg -c "widget" -g "*.ts" --stats

# List files still containing pattern
rg -l "widget" -g "*.ts" -g "*.tsx"

# Exclude vendor/node_modules (fd-style filtering)
rg -l "widget" -g "*.ts" -g "!vendor/**" -g "!node_modules/**"

7. Debug batch-refactor commands

If a batch command returns 0 results unexpectedly:

# 1. Verify rg finds matches directly
rg -l "pattern" -g "*.ts"

# 2. Check the glob syntax
# Bad:  --glob "**/*.{ts,tsx}"   (shell may expand braces)
# Good: --glob "**/*.ts" --glob "**/*.tsx"  (separate globs)

# 3. Run with verbose output
DEBUG=* bun tools/refactor.ts pattern.replace --pattern '/widget/i' --replace 'gadget' --glob "**/*.ts"