contact messages: editor preview renders no button when messaging disabled

The preview registered the {contact:} directive unconditionally, so with
no configured label it showed the button with the 'Contact us'
placeholder while the served page renders nothing. Mirror the page
logic in the preview render path.

docs/messages.md

@@ -36,15 +36,15 @@ A lone `{contact: Label}` line in article Markdown (the block-directive
 machinery of `markdown.py`) renders
 `<button class="contact-trigger">Label</button>`. An empty label falls
 back to the configured site label (`Data.contact_label`, localized —
-below; "Contact us" appears only as the inert preview's placeholder when
-nothing is configured). `pagerite.js`
+below; "Contact us" is the last-resort fallback when neither is set).
+`pagerite.js`
 click-delegates these buttons and lazy-loads
 the contact bundle; the editor preview renders the same button inert, and
 description/card mining resolves the tag to nothing. A per-button label
 lives in the chunk, so translated pages localize it like any other text.
 Feeds render the tag as its literal source (no directive context). When
 messaging is disabled (no site label configured) the tag renders nothing
-at all.
+at all, in the editor preview just as on the served page.
 
 ## Site settings and localization
 

pagerite/api.py

@@ -600,13 +600,18 @@ async def editor_ws(ws: WebSocket) -> None:
                     chain = resolve(data.menu, path)
                     node = chain[-1] if chain else None
                     has_cards_tag = views._CARDS_TAG_RE.search(markdown) is not None
-                    # {contact} buttons preview like the served page (inert);
-                    # {cards} expands like page_content does, so the preview
-                    # shows real cards, not the literal tag. No translation
-                    # context: the preview has no lang of its own, so cards
-                    # render in their originals.
+                    # {contact} buttons preview like the served page: inert,
+                    # and nothing at all when messaging is disabled (no
+                    # configured label). {cards} expands like page_content
+                    # does, so the preview shows real cards, not the literal
+                    # tag. No translation context: the preview has no lang of
+                    # its own, so cards render in their originals.
                     directives: dict = {
-                        "contact": lambda args, _env: views._contact_tag(args, _env, data)
+                        "contact": (
+                            (lambda args, _env: views._contact_tag(args, _env, data))
+                            if data.contact_label.strip()
+                            else (lambda _args, _env: "")
+                        )
                     }
                     if node is not None and has_cards_tag:
                         directives["cards"] = (

pagerite/views.py

@@ -1024,9 +1024,11 @@ def _contact_tag(args: str, _env: dict, data: Data | None = None, lang: str = ""
     """Expand a ``{contact: Label}`` directive: the button that opens the
     visitor contact panel (docs/messages.md). The args are a per-button
     label overriding the configured site label (Data.contact_label,
-    localized here; "Contact us" is just the inert preview's placeholder
-    when nothing is configured). pagerite.js binds the click and
-    lazy-loads the panel bundle; in the editor preview it stays inert."""
+    localized here; "Contact us" is the last-resort fallback). Callers
+    expand the tag only when messaging is enabled — with a blank
+    contact_label the tag renders nothing at all. pagerite.js binds the
+    click and lazy-loads the panel bundle; in the editor preview the
+    button stays inert."""
     label = args.strip()
     if not label and data is not None:
         label = i18n.site_string(data, lang, data.contact_label)