opencode-morph-fast-apply

OpenCode plugin for Morph Fast Apply - 10x faster code editing with lazy edit markers.

Features

• 10,500+ tokens/sec code editing via Morph's Fast Apply API
• Lazy edit markers (// ... existing code ...) - no exact string matching needed
• 98% accuracy with intelligent code merging
• Pre-flight validation - prevents accidental file deletions when markers are missing
• Unified diff output with context for easy review
• Custom TUI display - branded titles like Morph: src/file.ts +15/-3 (450ms)
• Graceful fallback - suggests native edit tool on API failure

Note: This is an OpenCode plugin that wraps Morph's Fast Apply API. For the official Morph MCP server (which includes WarpGrep search), see @morphllm/morphmcp. This plugin uses morph_edit as the tool name to avoid conflicts if you have both installed.

Installation

1. Add the plugin and always-on instruction to your OpenCode config

Preferred when your setup syncs packaged instructions into ~/.config/opencode/instructions/:

Add to your global config (~/.config/opencode/opencode.json):

{
  "instructions": ["~/.config/opencode/instructions/morph-tools.md"],
  "plugin": ["github:JRedeker/opencode-morph-fast-apply"]
}

Or pin to a specific version:

{
  "instructions": ["~/.config/opencode/instructions/morph-tools.md"],
  "plugin": ["github:JRedeker/opencode-morph-fast-apply#v1.11.0"]
}

Recommended setup summary:

• Prefer the stable synced instruction path: ~/.config/opencode/instructions/morph-tools.md
• Use the packaged node_modules/.../morph-tools.md path only when your setup does not sync instructions
• Keep the routing policy in the OpenCode instructions array, not a skill

If you are installing the plugin directly and do not sync packaged instructions into ~/.config/opencode/instructions/, you can point OpenCode at the packaged file instead:

{
  "instructions": [
    "~/.config/opencode/node_modules/opencode-morph-fast-apply/instructions/morph-tools.md"
  ],
  "plugin": ["github:JRedeker/opencode-morph-fast-apply"]
}

The morph_edit tool description remains self-contained, but for more reliable tool selection you should also load the packaged always-on instruction file shown above. This avoids agents defaulting to native edit when morph_edit is the better fit for large, scattered, or whitespace-sensitive edits.

Important: the active agent must also expose morph_edit in its tool manifest. If an agent profile marks morph_edit: false, the model cannot choose Morph even when the plugin is installed and the always-on instruction is present.

2. Set your Morph API key

Get an API key at morphllm.com/dashboard, then add it to the environment that starts OpenCode:

export MORPH_API_KEY="sk-your-key-here"

The plugin reads MORPH_API_KEY from the OpenCode process environment when it loads. Setting the variable in an unrelated shell does not update already-running OpenCode sessions.

3. Restart OpenCode

The morph_edit tool will now be available.

Usage

The LLM uses morph_edit for efficient partial file edits:

morph_edit({
  target_filepath: "src/auth.ts",
  instructions: "I am adding error handling for invalid tokens",
  code_edit: `// ... existing code ...
function validateToken(token) {
  if (!token) {
    throw new Error("Token is required");
  }
  // ... existing code ...
}
// ... existing code ...`
})

When to use morph_edit vs edit

Configuration

Available Models

How It Works

1. Reads the original file content
2. Sends to Morph API:
   • <instruction> - Your intent description
   • <code> - The complete original file
   • <update> - Your partial edit with markers
3. Morph intelligently merges the lazy edit markers with original code
4. Writes the merged result back to the file
5. Returns a unified diff showing what changed

Troubleshooting

"MORPH_API_KEY not configured"

Ensure the environment variable is set and exported in the shell or service that starts OpenCode:

echo $MORPH_API_KEY  # Should show your key

After changing MORPH_API_KEY, restart OpenCode so the plugin reloads with the updated OpenCode process environment.

Timeout errors

Increase the timeout for large files:

export MORPH_TIMEOUT=60000  # 60 seconds

Unexpected deletions

If code is being deleted unexpectedly, ensure your code_edit includes // ... existing code ... markers at the start and end. Omitting these markers tells Morph to replace the entire file.

Safety guards

The plugin blocks unsafe Morph responses before writing files:

• Marker leakage guard: If merged output contains // ... existing code ... but the original file did not, the write is aborted.
• Catastrophic truncation guard: If merged output loses more than 60% of characters and more than 50% of lines (for marker-based edits), the write is aborted.
• Dropped imports guard: If top-level import identifiers present in the original file are missing from the merged output, the write is aborted. This catches silent import loss that can occur when edits fall outside the anchoring context.
• Path confinement: All target paths are resolved and confined to the project root. Symlinks are followed and validated; paths that resolve outside the root are rejected.
• Secret scrubbing: API error messages are automatically scrubbed to prevent leaking your MORPH_API_KEY or Bearer tokens in tool output.

In all guard cases, morph_edit returns a detailed error with recovery options (retry with tighter anchors, use native edit, or split into smaller edits).

Markdown-fenced code_edit input

If an AI agent wraps code_edit in markdown fences (for example, ```typescript ... ```), morph_edit strips the outer fence before sending content to Morph.

Wrong edit location

If edits are applied to the wrong location, add more unique context around your changes and make your instructions more specific about which function/section you're modifying.

Native edit recovery

When a native edit reports an unmatched or ambiguous exact target:

1. Re-read the target file before any retry.
2. Do not repeat the unchanged failed edit input.
3. Make at most one corrected native edit only when the re-read proves the change is still small and exact.
4. Otherwise use morph_edit for the contextual repair — multi-line, scattered, whitespace-sensitive, or broader anchoring.
5. Use write only for new-file or intentional full-file replacement.

This recovery sequence is separate from the Morph API-error/timeout fallback, which still recovers to native edit.

Tool blocked in plan/explore mode

The morph_edit tool is disabled in readonly agent modes (plan, explore). Switch to a build/code mode to make edits.

Changelog

Unreleased

• Native edit recovery policy — The embedded morph_edit description, the packaged always-on instruction, and the README now share the same bounded recovery sequence for a failed native exact edit: re-read the target, do not repeat unchanged input, allow at most one corrected native edit only when still small and exact, otherwise hand off to morph_edit for contextual repair. The existing Morph API-error/timeout → native edit fallback is preserved.
• Drift regression tests — Content-level tests assert the recovery policy is present and consistent across all three routing surfaces.

v1.8.2

• Tool exposure requirement docs — instructions/morph-tools.md now documents that agent profiles must expose morph_edit: true in their tool manifest for the routing policy to take effect
• README alignment — Installation section notes the tool manifest requirement alongside the always-on instruction
• Test coverage — Tests verify the tool exposure section exists in the instruction file and README

v1.8.1

• Stable instruction path guidance - README now prefers ~/.config/opencode/instructions/morph-tools.md and keeps the packaged node_modules/... path as a fallback for direct installs
• Canonical routing policy wording - instructions/morph-tools.md now explicitly says morph routing belongs in always-on instructions, not a skill
• Docs/test alignment - Tests now verify the stable instruction path and canonical policy wording

v1.8.0

• Packaged always-on instruction - instructions/morph-tools.md now ships with the plugin so OpenCode can load reliable morph_edit selection guidance through the instructions array
• Packaging coverage - package metadata now includes the instructions/ directory, and tests verify that the shipped instruction path is documented
• Installation docs updated - README now recommends adding the packaged always-on instruction to global OpenCode config for more reliable morph_edit selection

v1.7.0

• Self-contained tool description — Core morph_edit guidance still lives in the tool description so the tool is usable even without extra setup.
• Packaged always-on instruction — instructions/morph-tools.md can be added to your OpenCode instructions array so agents choose morph_edit more reliably.
• Removed skill pattern — Deleted skills/morph/SKILL.md and MORPH_INSTRUCTIONS.md. The skill added a round-trip and split-brain problem where guidance lived in multiple places.
• Removed MORPH_SKILL_LOAD_HINT — Agents no longer need to load a skill before using morph_edit.

v1.6.0

• Post-merge safety guards - Blocks unsafe Morph output before writing to disk:
  • Marker leakage guard - Detects when merge model treats // ... existing code ... as literal text
  • Truncation guard - Dual-metric validation (>60% char + >50% line loss) prevents silent data loss
• Input normalization - Strips markdown fences from code_edit to prevent merge confusion
• TUI guard titles - Shows Morph: blocked (marker leakage) or Morph: blocked (truncation) on guard failures
• 32 test cases - Comprehensive coverage of normalization, leakage detection, and truncation edge cases

v1.5.0

• Custom TUI display - Tool output shows branded titles like Morph: src/file.ts +15/-3 (450ms)
• API timing - Response time tracked and displayed in tool title
• Structured metadata - Provider, version, model info included for future TUI enhancements

v1.4.0

• Fixed stdout pollution - Replaced console.log/console.warn with client.app.log() SDK method
• Readonly agent protection - Blocks morph_edit in plan and explore modes to prevent accidental edits
• Stderr fallback - Graceful logging if SDK method unavailable

v1.3.0

• Pre-flight validation prevents accidental deletions - Tool now returns an error if code_edit is missing markers for files >10 lines, preventing catastrophic code loss
• Improved code_edit parameter description - Changed from "Only the changed lines" to "The code changes wrapped with markers" to emphasize wrapping
• Added explicit wrapping rule - Tool description now includes "ALWAYS wrap your changes with markers at the start AND end"
• Restored comprehensive examples - MORPH_INSTRUCTIONS.md now includes all key examples (adding functions, modifying code, deletions)
• Added Quick Reference - Aligned with Morph's official agent instructions format
• Added fetch timeout example - From official Morph documentation

v1.2.0

• Tool schema aligned with Morph official spec - Tool description now matches Morph's recommended format
• Concise AI agent instructions - MORPH_INSTRUCTIONS.md reduced by 72% (237→67 lines) while keeping critical guidance
• Added marker validation warning - Server logs warn when code_edit is missing markers (helps debug unexpected deletions)
• Documentation improvements - Added troubleshooting section, model comparison table, updated config paths

v1.1.0

• Initial public release
• Morph Fast Apply integration with lazy edit markers
• Unified diff output
• Graceful fallback suggestions

Contributing

Contributions welcome! This plugin could potentially be integrated into OpenCode core.

This project uses Bun. The bun.lock lockfile is tracked in git; pnpm-lock.yaml and package-lock.json are ignored.

License

MIT