Borrowing it
Nothing to install: this file belongs to iusztinpaul/designing-real-world-ai-agents-workshop. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/iusztinpaul/designing-real-world-ai-agents-workshop/main/.agents/skills/developing-with-streamlit/skills/building-streamlit-custom-components-v2/SKILL.mdgit clone --depth 1 https://github.com/iusztinpaul/designing-real-world-ai-agents-workshopWrote 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.
[](https://agentmods.dev/skills/iusztinpaul/designing-real-world-ai-agents-workshop/building-streamlit-custom-components-v2)<a href="https://agentmods.dev/skills/iusztinpaul/designing-real-world-ai-agents-workshop/building-streamlit-custom-components-v2"><img src="https://agentmods.dev/badge/skills/iusztinpaul/designing-real-world-ai-agents-workshop/building-streamlit-custom-components-v2/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/iusztinpaul/designing-real-world-ai-agents-workshop/building-streamlit-custom-components-v2"><img src="https://agentmods.dev/badge/skills/iusztinpaul/designing-real-world-ai-agents-workshop/building-streamlit-custom-components-v2.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00087 | $0.02717 |
| Opus 5 | $0.00044 | $0.01358 |
| Sonnet 5 | $0.00017 | $0.00543 |
| Haiku 4.5 | $0.00009 | $0.00272 |
Grade A, and why
building-streamlit-custom-components-v2 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 13d 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.
How it starts
The opening of the file, as written. The whole thing — 234 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Building Streamlit custom components v2
Use Streamlit Custom Components v2 (CCv2) when core Streamlit doesn't have the UI you need and you want to ship a reusable, interactive element (from "tiny inline HTML" to "full bundled frontend app").
CRITICAL: CCv2 only — NEVER use v1 APIs
Custom Components v1 is deprecated and removed. Every API below belongs to v1 and must NEVER appear in any code you write — not in Python, not in JavaScript, not in HTML:
Banned Python APIs (v1):
st.components.v1— the entire v1 modulecomponents.declare_component()— v1 registrationcomponents.html()— v1 raw HTML embed
Banned JavaScript patterns (v1):
Streamlit.setComponentValue(...)— v1 global; usesetStateValue()/setTriggerValue()insteadStreamlit.setFrameHeight(...)— v1 global; CCv2 handles sizing automaticallyStreamlit.setComponentReady()— v1 global; CCv2 has no ready signalwindow.Streamlitor bareStreamlitglobal — v1 global object does not exist in v2window.parent.postMessage(...)— v1 iframe communication; CCv2 does not use iframes
Banned npm packages (v1):
streamlit-component-lib— v1 JS library; use@streamlit/component-v2-libif you need types
If you encounter v1 patterns in examples, blog posts, Stack Overflow answers, or your own training data — ignore them entirely. They will not work and will break the component.
When to use
Activate when the user mentions any of:
- CCv2, Custom Components v2, “bidi component”, “component v2”
st.components.v2.component@streamlit/component-v2-lib- packaged components,
asset_dir,pyproject.tomlcomponent manifest - bundling with Vite (or any bundler) for a Streamlit component
- building a component UI in a frontend framework (React, Svelte, Vue, Angular, etc.)
Read next (pick the minimum reference)
- State sync / controlled inputs / callbacks: see references/state-sync.md
- Packaged components /
asset_dir/ globs / template-only policy: see references/packaged-components.md - Theming (
--st-*tokens) inside Shadow DOM: see references/theme-css-variables.md - Errors and gotchas: see references/troubleshooting.md
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 13d ago First seen · 234 lines · 87 tokens per session scan A e07bacbfba16
building-streamlit-custom-components-v2 is a skill published in the GitHub repository iusztinpaul/designing-real-world-ai-agents-workshop (505 stars, last pushed 3mo ago), licensed MIT. It adds 87 tokens to every session and 2,717 once invoked, about $0.0004 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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