EDITFAST

Custom-tool reproduction of opencode-fast-apply for OpenCode, bypassing OpenCode bugs #33455 and #31354 via the custom tools pathway.

Why

The opencode-fast-apply plugin relies on OpenCode's plugin system, which has two unfixed bugs in v1.18.9:

• #33455: Config-array plugins are not loaded
• #31354: Hooks.tool is not bridged to ToolRegistry

EDITFAST sidesteps both by using OpenCode's custom tools scanning ({tool,tools}/*.{js,ts}), which is loaded through a completely separate code path that works correctly. See docs/research/custom-tools-pathway.md for the full audit.

Install

# Clone and install deps
git clone https://github.com/humbleangel/EDITFAST.git
cd EDITFAST
bun install

# Deploy to OpenCode custom tools directory
bun run install

Or manually:

mkdir -p ~/.config/opencode/tools
cp src/tool.ts ~/.config/opencode/tools/fast_apply_edit.ts

Once deployed, restart OpenCode. The tool fast_apply_edit will be available.

Configure

Var	Default	Description
FAST_APPLY_URL	http://localhost:1234/v1	OpenAI-compatible API base URL
FAST_APPLY_MODEL	fastapply-1.5b	Model name to use
FAST_APPLY_API_KEY	optional-api-key	Bearer token for API authentication

Usage

The tool is called automatically by the LLM when editing existing files. It accepts:

• target_filepath — path of the file to modify (relative to project root)
• original_code — 50–500 lines of context around the section to change
• code_edit — the updated code with // ... existing code ... markers for omitted sections

Example

The LLM will structure its call like:

fast_apply_edit({
  target_filepath: "src/foo.ts",
  original_code: "function bar() {\n  return 1\n}",
  code_edit: "function bar() {\n  return 42\n}"
})

Troubleshooting

Error	Cause	Action
Cannot locate original_code	File content doesn't match	Re-read the file and retry
appears N times	Match is ambiguous	Provide more context lines
FAST_APPLY_API_KEY not configured	Missing env var	Set FAST_APPLY_API_KEY
API error (status)	API unavailable or error	Check API server, fall back to native edit
Failed to parse AI response	API returned unexpected format	Check model compatibility

Development

bun install          # Install dependencies
bun test             # Run test suite
bun run typecheck    # TypeScript type checking
bun run install      # Deploy to OpenCode

Limitations

• No TUI notifications — the custom-tool API doesn't provide a client object for progress/spinner updates
• Same limitations as the upstream opencode-fast-apply plugin
• Requires an OpenAI-compatible API endpoint

Credits

Design and implementation derived from tickernelz/opencode-fast-apply, the original plugin this tool reproduces.

License

MIT