montage AGENTS.md

A repository guide for a Next.js and Remotion project used to create programmatic videos. It explains the local services, rendering commands, and special limitations in Cursor Cloud containers.

In plain words
What is it for?
Running the web interface and video preview tools, rendering still frames or selected video ranges, and developing safely without unnecessary database, Docker, or external services.
Why use it?
It prevents developers from starting the wrong service or rendering workflow in a restricted environment. It also encourages checking individual frames and sections while editing.

Instructions file for CodexOpenCode

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 instructions/simplexlabs/montage/agents-md
Clone the repo
git clone --depth 1 https://github.com/simplexlabs/montage

Made for: Codex, OpenCode.

Per session 4,917 This file is loaded in full into every session.
When invoked 4,917 The same file — it is already loaded in full.
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 $0.04917 $0.04917
Opus 5 $0.02459 $0.02459
Sonnet 5 $0.00983 $0.00983
Haiku 4.5 $0.00492 $0.00492

Measured 2d ago against content hash 21892605bf1d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

montage AGENTS.md 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 2d 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.

AGENTS.md · 372 lines

How it starts

The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Cursor Cloud specific instructions

Overview

This is a Next.js + Remotion programmatic video editing project. There are two dev services:

  • Remotion Studio — interactive preview/editing environment for video compositions
  • Next.js dev server — web UI with embedded @remotion/player

No database, Docker, or external services are required for local development.

Running services

See README.md for standard commands (npm run dev, npx remotion studio, etc.).

  • Remotion Studio (local non-Cursor only): npx remotion studio src/remotion/index.ts (default port 3000; use --port 3123 to avoid conflicts with Next.js)
  • Cursor/Cloud containers: do not run npx remotion studio (it can crash Cursor containers). Instead, render individual frames (npx remotion still) and individual section segments (npx remotion render --frames=<start>-<end>).
  • Next.js dev: npm run dev (port 3000)
  • Render a still frame: npx remotion still src/remotion/index.ts <CompositionId> --frame=<N> --output=/tmp/frame.png

Rendering workflow

Do NOT one-shot all sections at once without viewing them. For each section and each change you make to a section/sequence in the master composition, you MUST render stills and visually inspect them before moving on. Build one section → register it → render key frames → verify → then move to the next. Always show the rendered stills inline so the user can glance at progress. Do NOT ask for approval — just show and keep moving.

Render stills to inspect animations frame-by-frame:

npx remotion still src/remotion/index.ts <CompositionId> --frame=<N> --output=/tmp/frame.png

Render a section as MP4 to show completed work:

npx remotion render src/remotion/index.ts <CompositionId> --output=/opt/cursor/artifacts/<name>.mp4 --frames=<start>-<end> --concurrency=1

Render the full composition:

npx remotion render src/remotion/index.ts <CompositionId> --output=/opt/cursor/artifacts/<name>.mp4 --concurrency=1

Read the full file on GitHub · 372 lines

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. 2d ago First seen · 372 lines · 4,917 tokens per session scan A 21892605bf1d

Subscribe to this mod's changes

montage AGENTS.md is an instructions file published in the GitHub repository simplexlabs/montage (23 stars, last pushed 6mo ago), licensed MIT. It adds 4,917 tokens to every session, about $0.0246 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 2026-08-30.

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