Restructure Specs section into Architecture, Core, and Adapters pages

- Add Architecture intro page explaining the spec's two-layer design
  (core language + selectable adapters) with dependency graph
- Split specs into Core (parser, eval, primitives, render) and
  Adapters (DOM, HTML, SX wire, SxEngine) overview pages
- Add individual detail pages for all adapter and engine specs
- Update nav with Architecture landing, Core, Adapters, and all
  individual spec file links

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

sx/sxc/pages/docs.sx

@@ -253,11 +253,10 @@
   :layout (:sx-section
     :section "Specs"
     :sub-label "Specs"
-    :sub-href "/specs/core"
-    :sub-nav (~section-nav :items specs-nav-items :current "Core")
-    :selected "Core")
-  :data (spec-data "core")
-  :content (~spec-core-content :spec-files spec-files))
+    :sub-href "/specs/"
+    :sub-nav (~section-nav :items specs-nav-items :current "Architecture")
+    :selected "Architecture")
+  :content (~spec-architecture-content))
 
 (defpage specs-page
   :path "/specs/<slug>"
@@ -265,7 +264,7 @@
   :layout (:sx-section
     :section "Specs"
     :sub-label "Specs"
-    :sub-href "/specs/core"
+    :sub-href "/specs/"
     :sub-nav (~section-nav :items specs-nav-items
                :current (find-current specs-nav-items slug))
     :selected (or (find-current specs-nav-items slug) ""))
@@ -273,7 +272,8 @@
   :content (if spec-not-found
     (~spec-not-found :slug slug)
     (case slug
-      "core" (~spec-core-content :spec-files spec-files)
+      "core" (~spec-overview-content :spec-files spec-files)
+      "adapters" (~spec-overview-content :spec-files spec-files)
       :else (~spec-detail-content
         :spec-title spec-title
         :spec-desc spec-desc

sx/sxc/pages/helpers.py

@@ -104,21 +104,28 @@ def _reference_data(slug: str) -> dict:
     }
 
 
-_SPEC_FILES = {
+_CORE_SPECS = {
     "parser": ("parser.sx", "Parser", "Tokenization and parsing of SX source text into AST."),
     "evaluator": ("eval.sx", "Evaluator", "Tree-walking evaluation of SX expressions."),
     "primitives": ("primitives.sx", "Primitives", "All built-in pure functions and their signatures."),
-    "renderer": ("render.sx", "Renderer", "Rendering evaluated expressions to DOM, HTML, or SX wire format."),
+    "renderer": ("render.sx", "Renderer", "Shared rendering registries and utilities used by all adapters."),
 }
 
+_ADAPTER_SPECS = {
+    "adapter-dom": ("adapter-dom.sx", "DOM Adapter", "Renders SX expressions to live DOM nodes. Browser-only."),
+    "adapter-html": ("adapter-html.sx", "HTML Adapter", "Renders SX expressions to HTML strings. Server-side."),
+    "adapter-sx": ("adapter-sx.sx", "SX Wire Adapter", "Serializes SX for client-side rendering. Component calls stay unexpanded."),
+    "engine": ("engine.sx", "SxEngine", "Fetch/swap/history engine for browser-side SX. Like HTMX but native to SX."),
+}
+
+_ALL_SPECS = {**_CORE_SPECS, **_ADAPTER_SPECS}
+
 
 def _spec_data(slug: str) -> dict:
-    """Return spec file source and highlighted version for display."""
+    """Return spec file source and metadata for display."""
     import os
-    from content.highlight import highlight as _highlight
 
     ref_dir = os.path.join(os.path.dirname(__file__), "..", "..", "shared", "sx", "ref")
-    # Normalise — inside container shared is at /app/shared
     if not os.path.isdir(ref_dir):
         ref_dir = "/app/shared/sx/ref"
 
@@ -128,19 +135,28 @@ def _spec_data(slug: str) -> dict:
     if slug == "core":
         specs = []
         for key in ("parser", "evaluator", "primitives", "renderer"):
-            filename, title, desc = _SPEC_FILES[key]
+            filename, title, desc = _CORE_SPECS[key]
             filepath = os.path.join(ref_dir, filename)
             source = _read_spec(filepath)
             specs.append({
-                "title": title,
-                "desc": desc,
-                "filename": filename,
-                "source": source,
-                "href": f"/specs/{key}",
+                "title": title, "desc": desc, "filename": filename,
+                "source": source, "href": f"/specs/{key}",
             })
-        return {**base, "spec-title": "SX Core Specification", "spec-files": specs}
+        return {**base, "spec-title": "Core Language", "spec-files": specs}
 
-    info = _SPEC_FILES.get(slug)
+    if slug == "adapters":
+        specs = []
+        for key in ("adapter-dom", "adapter-html", "adapter-sx", "engine"):
+            filename, title, desc = _ADAPTER_SPECS[key]
+            filepath = os.path.join(ref_dir, filename)
+            source = _read_spec(filepath)
+            specs.append({
+                "title": title, "desc": desc, "filename": filename,
+                "source": source, "href": f"/specs/{key}",
+            })
+        return {**base, "spec-title": "Adapters & Engine", "spec-files": specs}
+
+    info = _ALL_SPECS.get(slug)
     if not info:
         return {**base, "spec-not-found": True}