Menubar

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<div class="menubar" data-menubar role="navigation" aria-label="App">
  <details class="menubar__item">
    <summary class="menubar__trigger">File</summary>
    <div class="menubar__panel" role="menu" aria-label="File"><a href="#" role="menuitem">New</a><a href="#" role="menuitem">Open…</a><button type="button" role="menuitem">Export</button></div>
  </details>
  <details class="menubar__item">
    <summary class="menubar__trigger">Edit</summary>
    <div class="menubar__panel" role="menu" aria-label="Edit"><button type="button" role="menuitem">Undo</button><button type="button" role="menuitem">Redo</button></div>
  </details>
  <details class="menubar__item">
    <summary class="menubar__trigger">View</summary>
    <div class="menubar__panel" role="menu" aria-label="View"><button type="button" role="menuitem">Zoom in</button><button type="button" role="menuitem">Zoom out</button></div>
  </details>
</div>

Server exchange

This Hyperpart has no server exchange — it is presentation or client chrome only. htmx does not issue a request on this part's behalf. If you put an affordance (hx-*) on a control that uses this markup, that action's exchange belongs to the action, not this part. See Swap contract for host-owned envelopes.

Swap contract

Agent-visible HTMX topology (ADR-0054 / decision 0012). exchange envelope = what the response may re-emit relative to the persistent slot (body_only | outer | none | host_owned | document). dual-lock validates part markup only — not this envelope. Stem: stems/morph-safe-hypermedia.md; decision: docs/decisions/0012-swap-identity-contract.md.

No host HTMX exchange on this part — presentation or client chrome only. exchange envelope: n/a.

If a host wraps this markup in hx-*, that host owns the swap contract (sole identity + envelope). Prefer innerMorph / outerMorph for stable slots; replacement for flash; body-only responses under inner swaps.

Envelope response examples

This part has no owned exchange (envelope n/a). If a host adds hx-*, that host’s envelope applies — typically body_only:

<!-- Host wraps this presentation part with hx-* (host owns envelope) -->
<!-- Prefer: hx-swap="innerMorph" hx-target="#panel-body" -->
<!-- Server returns body_only interior for #panel-body -->
<div class="dz-stack">content…</div>

Do not re-own the slot:

<!-- WRONG: server returns the presentation root with a new id every poll -->
<div id="menubar-root" data-dz-region>…</div>

How to use it

Seams

• `[data-menubar]` / `.menubar` root scopes exclusive open
• `details.menubar__item` + `summary.menubar__trigger` for panels
• pick-a-surface: File/Edit/View app chrome → menubar (not navigation-menu / menu)

Do / Don't

Pitfalls

• Native details allow multi-open and ignore outside click — never ship menubar without menubar.js
• Do not nest menubars; one root per chrome strip
• do not use menubar for marketing/product site IA — that is navigation-menu

Keyboard / AT

• role=menubar / menuitem on panel actions
• Keyboard: Enter/Space toggles summary; Escape dismisses open panels

Related parts

menu

DOM contract

What the emitted HTML must satisfy — the table is the required surface; Python under contracts/ is the package-internal dual-lock CI runs (tests/test_contracts.py), not an app route. Standalone HTMX4: implement the API so responses match this markup. Dazzle: the agent emits SSR that already satisfies it. Do not invent attrs outside these tables. For request/response wiring see Server exchange.

contracts/menubar.py

Required in the DOM: root [data-menubar] (part menubar). Emit only these attributes — inventing extras is fine only if controllers ignore them; omitting required ones fails CI (tests/test_contracts.py).

Module source

Import path is monorepo/package-local (from contracts._kit import …). Source-token form often uses data-*; gallery demos above are unprefixed. Do not copy this into app routes.

"""HYPERPART: menubar — app chrome exclusive-open root contract."""

from contracts._kit import DomContract, Node, Present

DOM_CONTRACT = DomContract(
    part="menubar",
    root="[data-dz-menubar]",
    nodes=(Node("[data-dz-menubar]", attrs={"data-dz-menubar": Present()}),),
)

__all__ = ["DOM_CONTRACT"]

Notes

Source files

One logical Hyperpart, 4 code items (CSS layered, JS bundled). Bound by HYPERPART: menubar — python tools/hyperpart.py menubar lists them.

site/registry.py · contracts/menubar.py · components/menubar.css:1 · controllers/dz-menubar.js