preview

A command set for managing a local development preview server.

In plain words
What is it for?
Use it to start or stop the server, view its URL and health, restart it, or check whether it is running.
Why use it?
It keeps starting, stopping, restarting, checking, and handling port conflicts in one place.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/felipeslo/opencode-kit/preview
Clone the repo
git clone --depth 1 https://github.com/felipeslo/opencode-kit
Per session 15 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 310 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00015 $0.00310
Opus 5 $0.00008 $0.00155
Sonnet 5 $0.00003 $0.00062
Haiku 4.5 $0.00002 $0.00031

Measured yesterday against content hash b0e5a59d3975, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

preview scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.opencode/commands/preview.md · 82 lines

What it actually says

/preview - Preview Management

$ARGUMENTS


Task

Manage preview server: start, stop, status check.

Commands

/preview           - Show current status
/preview start     - Start server
/preview stop      - Stop server
/preview restart   - Restart
/preview check     - Health check

Usage Examples

Start Server

/preview start

Response:
🚀 Starting preview...
   Port: 3000
   Type: Next.js

✅ Preview ready!
   URL: http://localhost:3000

Status Check

/preview

Response:
=== Preview Status ===

🌐 URL: http://localhost:3000
📁 Project: C:/projects/my-app
🏷️ Type: nextjs
💚 Health: OK

Port Conflict

/preview start

Response:
⚠️ Port 3000 is in use.

Options:
1. Start on port 3001
2. Close app on 3000
3. Specify different port

Which one? (default: 1)

Technical

Auto preview uses auto_preview.py script:

python .opencode/scripts/auto_preview.py start [port]
python .opencode/scripts/auto_preview.py stop
python .opencode/scripts/auto_preview.py status
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 82 lines · 15 tokens per session scan A b0e5a59d3975

Subscribe to this mod's changes

preview is a command published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 15 tokens to every session and 310 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.