self-contained-modals

A design rule for web dialogs that keeps their form fields and ongoing work inside the dialog, then removes them completely when the dialog closes.

In plain words
What is it for?
Use it when building or reviewing dialogs that start asynchronous work, such as OAuth sign-in popups, timers, subscriptions, or cancellable requests.
Why use it?
It prevents old timers, network requests, sign-ins, and other unfinished work from leaving the dialog stuck when it is opened again.

Skill for Claude CodeCodex

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 skills/usefulsoftwareco/executor/self-contained-modals
Any agent
npx skills add UsefulSoftwareCo/executor --skill self-contained-modals
Clone the repo
git clone --depth 1 https://github.com/UsefulSoftwareCo/executor

Made for: Claude Code, Codex.

Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 867 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 $0.00068 $0.00867
Opus 5 $0.00034 $0.00434
Sonnet 5 $0.00014 $0.00173
Haiku 4.5 $0.00007 $0.00087

Measured 2d ago against content hash 8704e420ee0f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

self-contained-modals 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.

.claude/skills/self-contained-modals/SKILL.md · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Self-contained modals

A modal's form state and in-flight work live INSIDE the modal, and closing the modal UNMOUNTS that state so it is destroyed, not hand-reset. Only the open/route intent belongs to the parent (deep links, programmatic open, reconnect handoffs need it).

Why

A hand-written reset() has to enumerate every field, and it silently drifts out of sync with state owned by child hooks the parent can't see. Unmounting resets everything for free, including child-hook cleanup effects (cancelling a dangling server session, clearing a timer, aborting a fetch).

Concrete bug this prevents (executor, add-account-modal): the modal was mounted unconditionally, so useOAuthPopupFlow's busy survived close. reset() zeroed its own booleans but never called oauthPopup.cancel(). Abandon the OAuth popup, close, reopen, and oauthBusy = false || busy(true) = true, so the footer is wedged on "Connecting…" with Close disabled. Unmounting would have cleared busy AND run the hook's cleanup that cancels the server OAuth session.

How to apply

Default to genuine conditional unmount, state inside. When closed the component returns null, so React destroys all of it and runs every child hook's cleanup. This is the cleanest fix and the one to reach for first:

function Parent() {
  const [open, setOpen] = useState(false);
  return open ? <Modal onClose={() => setOpen(false)} /> : null;
}

A key bump (<Body key={openCount} />) is still a manual reset, just spelled as a remount. Prefer real unmount; only reach for keyed remount in the one case below.

That case: Radix Dialog (this repo's components/dialog.tsx) Content/Overlay use data-[state=closed]:animate-out exit animations, so unmounting the whole Dialog drops the close animation. If you must keep that animation, keep the Dialog + DialogContent shell mounted and remount only the state-bearing body per open:

function Parent() {
  const [open, setOpen] = useState(false);
  const [openCount, setOpenCount] = useState(0);
  return (
    <Dialog open={open} onOpenChange={setOpen}>
      <DialogContent>{open ? <ModalBody key={openCount} /> : null}</DialogContent>
    </Dialog>
  );
}

Read the full file on GitHub · 78 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 · 78 lines · 68 tokens per session scan A 8704e420ee0f

Subscribe to this mod's changes

self-contained-modals is a skill published in the GitHub repository UsefulSoftwareCo/executor (3,466 stars, last pushed yesterday), licensed MIT. It adds 68 tokens to every session and 867 once invoked, about $0.0003 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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