Morph Fast Apply

Fast, AI-powered file editing using the Morph Apply API. Edit files without reading them first. Processes at 10,500 tokens/sec with 98% accuracy.

When to Use

• Fast file edits without reading entire file first
• Batch edits to a file (multiple changes in one operation)
• When you know what to change but file is large
• Large files where reading would consume too many tokens

Key Pattern: Code Markers

Use // ... existing code ... (or language-appropriate comments) to mark where edits go:

# ... existing code ...
try:
    result = process()
except Exception as e:
    log.error(e)
# ... existing code ...

The API intelligently places your edit in the right location.

Usage

Add error handling

uv run python -m runtime.harness scripts/mcp/morph_apply.py \
    --file "src/auth.py" \
    --instruction "Add error handling to login function" \
    --code_edit "# ... existing code ...
try:
    user = authenticate(credentials)
except AuthError as e:
    log.error(f'Auth failed: {e}')
    raise
# ... existing code ..."

Add logging

uv run python -m runtime.harness scripts/mcp/morph_apply.py \
    --file "src/api.py" \
    --instruction "Add debug logging" \
    --code_edit "# ... existing code ...
logger.debug(f'Processing request: {request.id}')
# ... existing code ..."

TypeScript example

uv run python -m runtime.harness scripts/mcp/morph_apply.py \
    --file "src/types.ts" \
    --instruction "Add user validation" \
    --code_edit "// ... existing code ...
if (!user) throw new Error('User not found');
if (!user.isActive) throw new Error('User inactive');
// ... existing code ..."

Parameters

Parameter	Description
--file	File path to edit (required)
--instruction	Human description of the change (required)
--code_edit	Code snippet with markers showing where to place edit (required)

vs Claude's Edit Tool

Tool	Best For
morph-apply	Fast edits, don't need to read file first, large files, batch edits
Claude Edit	Small precise edits when file is already in context

Use morph-apply when:

• File is not in context and reading it would be expensive
• File is very large (>500 lines)
• Making multiple related edits at once
• You know the context of the change (function name, class, etc.)

Use Claude Edit when:

• File is already in context from prior Read
• Very precise edits requiring exact old/new string matching
• Small files (<200 lines)

MCP Server Required

Requires morph server in mcp_config.json with MORPH_API_KEY.

Performance

• Speed: 10,500 tokens/sec
• Accuracy: 98% correct placement
• Token savings: Don't need to read entire file first