Enforce SX boundary contract via boundary.sx spec + runtime validation

Add boundary.sx declaring all 34 I/O primitives, 32 page helpers, and 9
allowed boundary types. Runtime validation in boundary.py checks every
registration against the spec — undeclared primitives/helpers crash at
startup with SX_BOUNDARY_STRICT=1 (now set in both dev and prod).

Key changes:
- Move 5 I/O-in-disguise primitives (app-url, asset-url, config,
  jinja-global, relations-from) from primitives.py to primitives_io.py
- Remove duplicate url-for/route-prefix from primitives.py (already in IO)
- Fix parse-datetime to return ISO string instead of raw datetime
- Add datetime→isoformat conversion in _convert_result at the edge
- Wrap page helper return values with boundary type validation
- Replace all SxExpr(f"...") patterns with sx_call() or _sx_fragment()
- Add assert declaration to primitives.sx

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

sx/content/highlight.py

@@ -238,7 +238,7 @@ def _tokenize_bash(code: str) -> list[tuple[str, str]]:
 
 def highlight(code: str, language: str = "lisp"):
     """Highlight code in the given language. Returns SxExpr for wire format."""
-    from shared.sx.parser import SxExpr
+    from shared.sx.parser import SxExpr, serialize
     if language in ("lisp", "sx", "sexp"):
         return SxExpr(highlight_sx(code))
     elif language in ("python", "py"):
@@ -246,5 +246,4 @@ def highlight(code: str, language: str = "lisp"):
     elif language in ("bash", "sh", "shell"):
         return SxExpr(highlight_bash(code))
     # Fallback: no highlighting, just escaped text
-    escaped = code.replace("\\", "\\\\").replace('"', '\\"')
-    return SxExpr(f'(span "{escaped}")')
+    return SxExpr("(span " + serialize(code) + ")")

sx/sx/nav-data.sx

@@ -97,7 +97,8 @@
 
 (define bootstrappers-nav-items (list
   (dict :label "Overview" :href "/bootstrappers/")
-  (dict :label "JavaScript" :href "/bootstrappers/javascript")))
+  (dict :label "JavaScript" :href "/bootstrappers/javascript")
+  (dict :label "Python" :href "/bootstrappers/python")))
 
 ;; Spec file registry — canonical metadata for spec viewer pages.
 ;; Python only handles file I/O (read-spec-file); all metadata lives here.

sx/sx/specs.sx

@@ -268,9 +268,11 @@ boot.sx             depends on: cssx, orchestration, adapter-dom, render")))
               (td :class "px-3 py-2 text-green-600" "Live"))
             (tr :class "border-b border-stone-100"
               (td :class "px-3 py-2 text-stone-700" "Python")
-              (td :class "px-3 py-2 font-mono text-sm text-stone-400" "bootstrap_py.py")
-              (td :class "px-3 py-2 font-mono text-sm text-stone-400" "shared/sx/")
-              (td :class "px-3 py-2 text-stone-400" "Planned"))
+              (td :class "px-3 py-2 font-mono text-sm text-violet-700"
+                (a :href "/bootstrappers/python" :class "hover:underline"
+                   "bootstrap_py.py"))
+              (td :class "px-3 py-2 font-mono text-sm text-stone-500" "sx_ref.py")
+              (td :class "px-3 py-2 text-green-600" "Live"))
             (tr :class "border-b border-stone-100"
               (td :class "px-3 py-2 text-stone-700" "Rust")
               (td :class "px-3 py-2 font-mono text-sm text-stone-400" "bootstrap_rs.py")
@@ -320,6 +322,47 @@ boot.sx             depends on: cssx, orchestration, adapter-dom, render")))
           (pre :class "text-xs leading-relaxed whitespace-pre-wrap break-words"
             (code (highlight bootstrapped-output "javascript"))))))))
 
+;; ---------------------------------------------------------------------------
+;; Python bootstrapper detail
+;; ---------------------------------------------------------------------------
+
+(defcomp ~bootstrapper-py-content (&key bootstrapper-source bootstrapped-output)
+  (~doc-page :title "Python Bootstrapper"
+    (div :class "space-y-8"
+
+      (div :class "space-y-3"
+        (p :class "text-stone-600"
+          "This page reads the canonical " (code :class "text-violet-700 text-sm" ".sx")
+          " spec files, runs the Python bootstrapper, and displays both the compiler source and its generated Python output. "
+          "The generated code below is live — it was produced by the bootstrapper at page load time.")
+        (p :class "text-xs text-stone-400 italic"
+          "With SX_USE_REF=1, the server-side SX evaluator running this page IS the bootstrapped output. "
+          "This page re-runs the bootstrapper to display the source and result."))
+
+      (div :class "space-y-3"
+        (div :class "flex items-baseline gap-3"
+          (h2 :class "text-2xl font-semibold text-stone-800" "Bootstrapper")
+          (span :class "text-sm text-stone-400 font-mono" "bootstrap_py.py"))
+        (p :class "text-sm text-stone-500"
+          "The compiler reads " (code :class "text-violet-700 text-sm" ".sx")
+          " spec files (eval, primitives, render, adapter-html) "
+          "and emits a standalone Python module. Platform bridge functions (type constructors, environment ops) "
+          "are emitted as native Python implementations.")
+        (div :class "bg-stone-100 rounded-lg p-5 max-h-96 overflow-y-auto border border-stone-200"
+          (pre :class "text-xs leading-relaxed whitespace-pre-wrap break-words"
+            (code (highlight bootstrapper-source "python")))))
+
+      (div :class "space-y-3"
+        (div :class "flex items-baseline gap-3"
+          (h2 :class "text-2xl font-semibold text-stone-800" "Generated Output")
+          (span :class "text-sm text-stone-400 font-mono" "sx_ref.py"))
+        (p :class "text-sm text-stone-500"
+          "The Python below was generated by running the bootstrapper against the current spec files. "
+          "It is a complete server-side SX evaluator — eval, primitives, and HTML renderer.")
+        (div :class "bg-stone-100 rounded-lg p-5 max-h-96 overflow-y-auto border border-violet-300"
+          (pre :class "text-xs leading-relaxed whitespace-pre-wrap break-words"
+            (code (highlight bootstrapped-output "python"))))))))
+
 ;; ---------------------------------------------------------------------------
 ;; Not found
 ;; ---------------------------------------------------------------------------

sx/sxc/pages/docs.sx

@@ -368,6 +368,10 @@
   :data (bootstrapper-data slug)
   :content (if bootstrapper-not-found
     (~spec-not-found :slug slug)
-    (~bootstrapper-js-content
-      :bootstrapper-source bootstrapper-source
-      :bootstrapped-output bootstrapped-output)))
+    (if (= slug "python")
+      (~bootstrapper-py-content
+        :bootstrapper-source bootstrapper-source
+        :bootstrapped-output bootstrapped-output)
+      (~bootstrapper-js-content
+        :bootstrapper-source bootstrapper-source
+        :bootstrapped-output bootstrapped-output))))

sx/sxc/pages/helpers.py

@@ -135,29 +135,44 @@ def _bootstrapper_data(target: str) -> dict:
     """
     import os
 
-    if target != "javascript":
+    if target not in ("javascript", "python"):
         return {"bootstrapper-not-found": True}
 
     ref_dir = os.path.join(os.path.dirname(__file__), "..", "..", "shared", "sx", "ref")
     if not os.path.isdir(ref_dir):
         ref_dir = "/app/shared/sx/ref"
 
-    # Read bootstrapper source
-    bs_path = os.path.join(ref_dir, "bootstrap_js.py")
-    try:
-        with open(bs_path, encoding="utf-8") as f:
-            bootstrapper_source = f.read()
-    except FileNotFoundError:
-        bootstrapper_source = "# bootstrapper source not found"
+    if target == "javascript":
+        # Read bootstrapper source
+        bs_path = os.path.join(ref_dir, "bootstrap_js.py")
+        try:
+            with open(bs_path, encoding="utf-8") as f:
+                bootstrapper_source = f.read()
+        except FileNotFoundError:
+            bootstrapper_source = "# bootstrapper source not found"
 
-    # Run the bootstrap to generate JS
-    from shared.sx.ref.bootstrap_js import compile_ref_to_js
-    try:
-        bootstrapped_output = compile_ref_to_js(
-            adapters=["dom", "engine", "orchestration", "boot", "cssx"]
-        )
-    except Exception as e:
-        bootstrapped_output = f"// bootstrap error: {e}"
+        # Run the bootstrap to generate JS
+        from shared.sx.ref.bootstrap_js import compile_ref_to_js
+        try:
+            bootstrapped_output = compile_ref_to_js(
+                adapters=["dom", "engine", "orchestration", "boot", "cssx"]
+            )
+        except Exception as e:
+            bootstrapped_output = f"// bootstrap error: {e}"
+
+    elif target == "python":
+        bs_path = os.path.join(ref_dir, "bootstrap_py.py")
+        try:
+            with open(bs_path, encoding="utf-8") as f:
+                bootstrapper_source = f.read()
+        except FileNotFoundError:
+            bootstrapper_source = "# bootstrapper source not found"
+
+        from shared.sx.ref.bootstrap_py import compile_ref_to_py
+        try:
+            bootstrapped_output = compile_ref_to_py()
+        except Exception as e:
+            bootstrapped_output = f"# bootstrap error: {e}"
 
     return {
         "bootstrapper-not-found": None,
@@ -176,7 +191,7 @@ def _attr_detail_data(slug: str) -> dict:
     - attr-not-found (truthy if not found)
     """
     from content.pages import ATTR_DETAILS
-    from shared.sx.helpers import SxExpr
+    from shared.sx.helpers import sx_call
 
     detail = ATTR_DETAILS.get(slug)
     if not detail:
@@ -193,7 +208,7 @@ def _attr_detail_data(slug: str) -> dict:
         "attr-description": detail["description"],
         "attr-example": detail["example"],
         "attr-handler": detail.get("handler"),
-        "attr-demo": SxExpr(f"(~{demo_name})") if demo_name else None,
+        "attr-demo": sx_call(demo_name) if demo_name else None,
         "attr-wire-id": wire_id,
     }
 
@@ -201,7 +216,7 @@ def _attr_detail_data(slug: str) -> dict:
 def _header_detail_data(slug: str) -> dict:
     """Return header detail data for a specific header slug."""
     from content.pages import HEADER_DETAILS
-    from shared.sx.helpers import SxExpr
+    from shared.sx.helpers import sx_call
 
     detail = HEADER_DETAILS.get(slug)
     if not detail:
@@ -214,14 +229,14 @@ def _header_detail_data(slug: str) -> dict:
         "header-direction": detail["direction"],
         "header-description": detail["description"],
         "header-example": detail.get("example"),
-        "header-demo": SxExpr(f"(~{demo_name})") if demo_name else None,
+        "header-demo": sx_call(demo_name) if demo_name else None,
     }
 
 
 def _event_detail_data(slug: str) -> dict:
     """Return event detail data for a specific event slug."""
     from content.pages import EVENT_DETAILS
-    from shared.sx.helpers import SxExpr
+    from shared.sx.helpers import sx_call
 
     detail = EVENT_DETAILS.get(slug)
     if not detail:
@@ -233,5 +248,5 @@ def _event_detail_data(slug: str) -> dict:
         "event-title": slug,
         "event-description": detail["description"],
         "event-example": detail.get("example"),
-        "event-demo": SxExpr(f"(~{demo_name})") if demo_name else None,
+        "event-demo": sx_call(demo_name) if demo_name else None,
     }