preview

preview is a command for coding agents from tinhtran24/maestro. It costs 0 tokens per session (277 once invoked), scanned A, original, Apache-2.0.

A command that opens a web address or local HTML file in Maestro's desktop browser panel. A local development server is a program running on your computer that serves a site for testing.

In plain words
What is it for?
Use it to open a workspace's default page, view a local development server, open a local HTML file, or clear the preview panel.
Why use it?
It lets you inspect a site or preview a file inside the current session without switching to another browser workflow.

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/tinhtran24/maestro/preview
Clone the repo
git clone --depth 1 https://github.com/tinhtran24/maestro

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for preview

README.md
[![agentmods](https://agentmods.dev/badge/commands/tinhtran24/maestro/preview.svg)](https://agentmods.dev/commands/tinhtran24/maestro/preview)
Your own site
<a href="https://agentmods.dev/commands/tinhtran24/maestro/preview"><img src="https://agentmods.dev/badge/commands/tinhtran24/maestro/preview.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 277 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 $0.00000 $0.00277
Opus 5 $0.00000 $0.00138
Sonnet 5 $0.00000 $0.00055
Haiku 4.5 $0.00000 $0.00028

Measured 4d ago against content hash 82719a01e9ee, 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 4d ago.

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.

backend/internal/skillassets/using-maestro/commands/preview.md · 63 lines

What it actually says

maestro preview

Open a URL in the desktop browser panel for the current session. With no argument it opens the workspace's static entry point, falling back to this session's existing preview target when no entry point exists. A local file can be opened by its absolute file:// URL. Use maestro preview clear to empty the panel.

Syntax

maestro preview [url] [flags]
maestro preview [command]

Flags

No flags beyond -h / --help.

Subcommands


maestro preview (bare form)

Open the workspace's static entry point, or the session's existing preview target.

Examples:

# Open the default entry point for this session's workspace
maestro preview
# Open a local dev server
maestro preview http://localhost:5173
(or wherever the dev server is running)
# Open a local HTML file
maestro preview file://$(pwd)/index.html

maestro preview clear

Clear the desktop browser panel for the current session.

Syntax:

maestro preview clear [flags]

Flags:

No flags beyond -h / --help.

Examples:

# Clear the preview panel
maestro preview clear
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. 4d ago First seen · 63 lines · 0 tokens per session scan A 82719a01e9ee

Subscribe to this mod's changes

preview is a command published in the GitHub repository tinhtran24/maestro (3 stars, last pushed 1mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 277 tokens. 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.