plain-htmx bundles htmx 1.x head-support extension with htmx 2.0.4 core #73

plain-htmx 0.20.0 ships htmx core 2.0.4 (.venv/.../plain/htmx/assets/htmx/vendor/src/htmx.js declares version: '2.0.4') but bundles the htmx 1.x version of the head-support extension. The extension self-warns when paired with a non-1.x core:

head-support.js:9 WARNING: You are using an htmx 1 extension with htmx 2.0.4.
It is recommended that you move to the version of this extension found on
https://htmx.org/extensions

Source of the warning, in the vendored extension:

// plain/htmx/assets/htmx/vendor/src/ext/head-support.js
// "An extension to htmx 1.0 to add head tag merging."
if (htmx.version && !htmx.version.startsWith("1.")) {
    console.warn("WARNING: You are using an htmx 1 extension with htmx " + htmx.version + ...)
}

Reproduction

{# base.html #}
{% htmx_js extensions=["head-support"] %}
<body hx-ext="head-support">

Load any page in the browser → warning fires in the console on every page load.

Suggested fix

For htmx 2.x, extensions moved to a separate repo: bigskysoftware/htmx-extensions. The v2-compatible head-support lives at https://github.com/bigskysoftware/htmx-extensions/tree/main/src/head-support. plain-htmx should vendor the v2 version of bundled extensions to match the core it ships.

Environment

• Plain: 0.146.0 (plain-htmx 0.20.0)
• Python: 3.13.3
• OS: Darwin 25.4.0

Submitted via the /plain-bug skill.