Add component deps to page registry, check before client routing

Each page entry now includes a deps list of component names needed.
Client checks all deps are loaded before attempting eval — if any
are missing, falls through to server fetch with a clear log message.
No bundle bloat: server sends components for the current page only.

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

shared/sx/helpers.py

@@ -644,12 +644,14 @@ def _build_pages_sx(service: str) -> str:
 
     Returns SX dict literals (one per page) parseable by the client's
     ``parse`` function.  Each dict has keys: name, path, auth, has-data,
-    content, closure.
+    content, closure, deps.
     """
     import logging
     _log = logging.getLogger("sx.pages")
     from .pages import get_all_pages
     from .parser import serialize as sx_serialize
+    from .deps import components_needed
+    from .jinja_bridge import _COMPONENT_ENV
 
     pages = get_all_pages(service)
     _log.debug("_build_pages_sx(%s): %d pages in registry", service, len(pages))
@@ -666,6 +668,12 @@ def _build_pages_sx(service: str) -> str:
         auth = page_def.auth if isinstance(page_def.auth, str) else "custom"
         has_data = "true" if page_def.data_expr is not None else "false"
 
+        # Component deps needed to render this page client-side
+        deps: set[str] = set()
+        if content_src and page_def.data_expr is None:
+            deps = components_needed(content_src, _COMPONENT_ENV)
+        deps_sx = "(" + " ".join(_sx_literal(d) for d in sorted(deps)) + ")"
+
         # Build closure as SX dict
         closure_parts: list[str] = []
         for k, v in page_def.closure.items():
@@ -679,6 +687,7 @@ def _build_pages_sx(service: str) -> str:
             + " :auth " + _sx_literal(auth)
             + " :has-data " + has_data
             + " :content " + _sx_literal(content_src)
+            + " :deps " + deps_sx
             + " :closure " + closure_sx + "}"
         )
         entries.append(entry)
@@ -702,6 +711,7 @@ def _sx_literal(v: object) -> str:
     return "nil"
 
 
+
 def sx_page(ctx: dict, page_sx: str, *,
               meta_html: str = "") -> str:
     """Return a minimal HTML shell that boots the page from sx source.

shared/sx/ref/orchestration.sx

@@ -543,24 +543,42 @@
 ;; Client-side routing
 ;; --------------------------------------------------------------------------
 
+(define has-all-deps?
+  (fn (deps)
+    ;; Check if all component deps are loaded in the client env.
+    ;; deps is a list of component name strings (e.g. "~essay-foo").
+    (let ((loaded (loaded-component-names))
+          (missing false))
+      (for-each
+        (fn (dep)
+          (when (not (contains? loaded dep))
+            (set! missing dep)))
+        deps)
+      (if missing
+        (do (log-info (str "sx:route missing component " missing)) false)
+        true))))
+
 (define try-client-route
   (fn (pathname)
     ;; Try to render a page client-side. Returns true if successful, false otherwise.
-    ;; Only works for pages without :data dependencies.
+    ;; Only works for pages without :data dependencies and with all deps loaded.
     (let ((match (find-matching-route pathname _page-routes)))
       (if (nil? match)
         (do (log-info (str "sx:route no match (" (len _page-routes) " routes) " pathname)) false)
         (if (get match "has-data")
           (do (log-info (str "sx:route server (has data) " pathname)) false)
           (let ((content-src (get match "content"))
+                (deps (or (get match "deps") (list)))
                 (closure (or (get match "closure") {}))
                 (params (get match "params")))
             (if (or (nil? content-src) (empty? content-src))
               (do (log-warn (str "sx:route no content for " pathname)) false)
-              (let ((env (merge closure params))
-                    (rendered (try-eval-content content-src env)))
-                (if (nil? rendered)
-                  (do (log-warn (str "sx:route eval failed for " pathname)) false)
+              (if (not (has-all-deps? deps))
+                (do (log-info (str "sx:route server (missing deps) " pathname)) false)
+                (let ((env (merge closure params))
+                      (rendered (try-eval-content content-src env)))
+                  (if (nil? rendered)
+                    (do (log-warn (str "sx:route eval failed for " pathname)) false)
                   (let ((target (dom-query-by-id "main-panel")))
                     (if (nil? target)
                       (do (log-warn "sx:route #main-panel not found") false)
@@ -571,7 +589,7 @@
                         (process-elements target)
                         (sx-hydrate-elements target)
                         (log-info (str "sx:route client " pathname))
-                        true))))))))))))
+                        true)))))))))))))
 
 
 (define bind-client-route-link