OpenCode Rate Limiter Plugin

Experimental — Proof of concept. No further development planned.
MIT licensed — feel free to fork, adapt, or use as reference.

A plugin for OpenCode that adds rate limiting and a concurrency semaphore to LLM requests.

Features

• Rate limiting — per-provider sliding window (e.g. max 1 request every 2s per provider)
• Concurrency semaphore — global cap on simultaneous LLM requests across all workspaces
• Shared state — survives module reloads via globalThis, consistent across all open workspaces

How It Works

                  chat.params hook
                ┌─────────────────────┐
   Request ──→  │  1. Rate check      │
                │  2. Acquire slot     │
                │  3. Mark window      │
                └─────────┬───────────┘
                          │ (waits if rate-limited
                          │  or concurrency full)
                          ▼
                    ┌─────────────┐
                    │  LLM Call   │
                    └─────────────┘
                          │
                    (slot auto-releases
                     after timeout)

Rate Limiter (per-provider sliding window)

• Each provider (nvidia, opencode, etc.) has its own rate window
• Maximum maxRatePerWindow requests per rateWindowMs milliseconds
• Excessive requests wait (sleep) until the window expires
• Uses a sliding window: old timestamps are pruned automatically

Concurrency Semaphore (global)

• Global Set of active request IDs, shared across all workspaces
• If activeRequests.size >= maxConcurrent, new requests wait with polling
• Each acquired slot has a safety timeout (requestTimeoutMs) that auto-releases if the request never completes
• Polling interval (checkIntervalMs) controls responsiveness

Installation

1. Copy the plugin

mkdir -p ~/.config/opencode/plugins
cp index.js ~/.config/opencode/plugins/rate-limiter.js

Or clone directly:

git clone https://github.com/tmogeid/opencode-rate-limiter-plugin.git
cp opencode-rate-limiter-plugin/index.js ~/.config/opencode/plugins/rate-limiter.js

2. Ensure package.json exists in plugins

echo '{"type":"module"}' > ~/.config/opencode/plugins/package.json

3. Restart OpenCode

The plugin auto-loads on next start. Check the log file to confirm.

Configuration

All settings are at the top of index.js inside the CONFIG object:

Variable	Default	Description
maxConcurrent	15	Max simultaneous requests across all providers/workspaces
maxRatePerWindow	1	Max requests per provider within the time window
rateWindowMs	2000	Time window for rate limiting (milliseconds)
requestTimeoutMs	15000	Safety timeout: auto-release concurrency slot after this time
checkIntervalMs	200	Polling interval for concurrency semaphore (milliseconds)

Presets

Conservative:

maxConcurrent: 5
maxRatePerWindow: 1
rateWindowMs: 3000

Balanced (default):

maxConcurrent: 15
maxRatePerWindow: 1
rateWindowMs: 2000

Aggressive:

maxConcurrent: 25
maxRatePerWindow: 2
rateWindowMs: 3000

Monitoring

Logs are written to:

• Windows: %TEMP%\opencode-rate-limiter\rate-limiter.log
• Linux/macOS: /tmp/opencode-rate-limiter/rate-limiter.log

Events

Event	Meaning
CONCURRENCY_ACQUIRED	A concurrency slot was granted
CONCURRENCY_BLOCKED	Request is waiting for a free slot
CONCURRENCY_TIMEOUT_RELEASE	Slot auto-released by safety timeout
CONCURRENCY_RELEASE	Slot explicitly released
RATE_LIMIT	Request is rate-limited (sleeping)
PASS	Request passed through

Live monitoring (PowerShell)

Get-Content "$env:TEMP\opencode-rate-limiter\rate-limiter.log" -Wait

Compatibility

• Tested with OpenCode v1.17.11 on Windows 11 Pro 64-bit only
• Works with any provider (nvidia, opencode, etc.)
• Shared state across all open workspaces (via globalThis)
• Module ESM format (type: module)

License

MIT — see LICENSE.

Contributing

This is an experimental proof of concept with no active development planned. Feel free to fork or submit PRs if you find it useful.