# `MishkaCmsCore.Sidebar.PageGuard`
[🔗](https://github.com/mishka-group/mishka_cms_core/blob/v0.0.1/lib/mishka_cms_core/sidebar.ex#L882)

`on_mount` hook that refuses an admin page to anyone whose permissions its declaration does not
allow. Attached once, in `MishkaCmsCore.ExtensionLiveView`, so it covers every admin LiveView
without a line in any of them.

It reads `socket.view` — the module the router resolved — never the URL. That is the whole
point: a URL is a string the client chooses and can spell more than one way
(`/admin/dashboard//account/permissions` routes to the same page as the single-slash form), while
the mounted module is a fact by the time this runs.

`mount` is the right callback for "may this user open this page": a direct URL goes through the
plug pipeline and mounts, and a `push_navigate` from another page skips the pipeline but still
mounts. A `push_patch` within the same page re-runs only `handle_params`, which is fine — same
page, same declaration, already decided here.

**Undeclared means refused.** A page with no entry in `MishkaCmsCore.Sidebar` gets `[]` and is
denied, so the failure mode of forgetting a declaration is a locked page, never an open one.

# `on_mount`

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*Consult [api-reference.md](api-reference.md) for complete listing*