Histogram

Copy this

<div class="histogram-region hm-measure-lg" data-histogram>
  <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 180 48" role="img" aria-label="Histogram — 6 buckets, 120 samples"><rect x="4" y="30" width="24" height="18" fill="var(--colour-brand)" fill-opacity="0.7"/><rect x="32" y="18" width="24" height="30" fill="var(--colour-brand)" fill-opacity="0.7"/><rect x="60" y="6" width="24" height="42" fill="var(--colour-brand)" fill-opacity="0.7"/><rect x="88" y="14" width="24" height="34" fill="var(--colour-brand)" fill-opacity="0.7"/><rect x="116" y="28" width="24" height="20" fill="var(--colour-brand)" fill-opacity="0.7"/><rect x="144" y="38" width="24" height="10" fill="var(--colour-brand)" fill-opacity="0.7"/></svg>
  <p class="histogram-summary">6 buckets · 120 samples</p>
</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="histogram-root" data-dz-region>…</div>

How to use it

No extended guidance authored yet — start from Copy this and the dependency chips (Primitive = markup only; controller = load listed JS; Endpoint = implement Server exchange).

Seams

• copy the partial under Copy this; keep root class and data-* modifiers so the CSS/JS bundle matches
• no Server exchange on this part — pure presentation or client chrome
• satisfy the DOM contract tables (CI stop-ship)

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/histogram.py

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

Ingestion model HistogramBin

Server-side shape before render — one normalisation boundary for producers.

Exemplar render()

Executable in CI: the Python below is render(); the boxed preview is render(EXEMPLARS[0]) — the first fixture the dual-lock tests emit, not a separate widget and not gallery mock data. Sample model: label=Latency.

def render(h: Histogram) -> str:
    """Model → histogram region."""
    if not h.bins:
        return (
            f'<div class="dz-histogram-region" data-dz-histogram>'
            f'<p class="dz-empty-dense" role="status">'
            f"{html.escape(h.empty_message)}</p>"
            f"</div>"
        )
    total = sum(b.count for b in h.bins)
    max_count = max(b.count for b in h.bins) or 1
    summary = (
        f'<p class="dz-histogram-summary">'
        f"{len(h.bins)} bins · {total} samples · peak {max_count}"
        f"</p>"
    )
    return f'<div class="dz-histogram-region" data-dz-histogram>{h.svg_html}{summary}</div>'

Notes

Source files

Canonical registration in the registry. No dedicated controller — CSS for this part lives in the layered bundle.

site/registry.py · contracts/histogram.py