Send all responses as sexp wire format with client-side rendering

- Server sends sexp source text, client (sexp.js) renders everything
- SexpExpr marker class for nested sexp composition in serialize()
- sexp_page() HTML shell with data-mount="body" for full page loads
- sexp_response() returns text/sexp for OOB/partial responses
- ~app-body layout component replaces ~app-layout (no raw!)
- ~rich-text is the only component using raw! (for CMS HTML content)
- Fragment endpoints return text/sexp, auto-wrapped in SexpExpr
- All _*_html() helpers converted to _*_sexp() returning sexp source
- Head auto-hoist: sexp.js moves meta/title/link/script[ld+json]
  from rendered body to document.head automatically
- Unknown components render warning box instead of crashing page
- Component kwargs preserve AST for lazy rendering (fixes <> in kwargs)
- Fix unterminated paren in events/sexp/tickets.sexpr

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/browser/app/utils/htmx.py

@@ -1,46 +1,28 @@
-"""HTMX utilities for detecting and handling HTMX requests."""
+"""SxEngine request detection utilities."""
 
 from quart import request
 
 
 def is_htmx_request() -> bool:
-    """
-    Check if the current request is an HTMX request.
+    """Check if the current request is an SxEngine request."""
+    return request.headers.get("SX-Request", "").lower() == "true"
 
-    Returns:
-        bool: True if HX-Request header is present and true
-    """
-    return request.headers.get("HX-Request", "").lower() == "true"
+
+def is_sx_request() -> bool:
+    """Check if the current request is an SxEngine request."""
+    return request.headers.get("SX-Request", "").lower() == "true"
 
 
 def get_htmx_target() -> str | None:
-    """
-    Get the target element ID from HTMX request headers.
-
-    Returns:
-        str | None: Target element ID or None
-    """
-    return request.headers.get("HX-Target")
+    """Get the target element ID from SX request headers."""
+    return request.headers.get("SX-Target")
 
 
 def get_htmx_trigger() -> str | None:
-    """
-    Get the trigger element ID from HTMX request headers.
-
-    Returns:
-        str | None: Trigger element ID or None
-    """
+    """Get the trigger element ID from request headers."""
     return request.headers.get("HX-Trigger")
 
 
 def should_return_fragment() -> bool:
-    """
-    Determine if we should return a fragment vs full page.
-
-    For HTMX requests, return fragment.
-    For normal requests, return full page.
-
-    Returns:
-        bool: True if fragment should be returned
-    """
+    """Determine if we should return a fragment vs full page."""
     return is_htmx_request()

shared/browser/app/utils/utils.py

@@ -41,7 +41,7 @@ def vary(resp: Response) -> Response:
     """
     v = resp.headers.get("Vary", "")
     parts = [p.strip() for p in v.split(",") if p.strip()]
-    for h in ("HX-Request", "X-Origin"):
+    for h in ("SX-Request", "HX-Request", "X-Origin"):
         if h not in parts:
             parts.append(h)
     if parts: