Refactor SX primitives: modular, isomorphic, general-purpose

Spec modularization:
- Add (define-module :name) markers to primitives.sx creating 11 modules
  (7 core, 4 stdlib). Bootstrappers can now selectively include modules.
- Add parse_primitives_by_module() to boundary_parser.py.
- Remove split-ids primitive; inline at 4 call sites in blog/market queries.

Python file split:
- primitives.py: slimmed to registry + core primitives only (~350 lines)
- primitives_stdlib.py: NEW — stdlib primitives (format, text, style, debug)
- primitives_ctx.py: NEW — extracted 12 page context builders from IO
- primitives_io.py: add register_io_handler decorator, auto-derive
  IO_PRIMITIVES from registry, move sync IO bridges here

JS parity fixes:
- = uses === (strict equality), != uses !==
- round supports optional ndigits parameter
- concat uses nil-check not falsy-check (preserves 0, "", false)
- escape adds single quote entity (') matching Python/markupsafe
- assert added (was missing from JS entirely)

Bootstrapper modularization:
- PRIMITIVES_JS_MODULES / PRIMITIVES_PY_MODULES dicts keyed by module
- --modules CLI flag for selective inclusion (core.* always included)
- Regenerated sx-ref.js and sx_ref.py with all fixes

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

shared/sx/ref/primitives.sx

@@ -18,13 +18,19 @@
 ;; The :body is optional — when provided, it gives a reference
 ;; implementation in SX that bootstrap compilers MAY use for testing
 ;; or as a fallback. Most targets will implement natively for performance.
+;;
+;; Modules: (define-module :name) scopes subsequent define-primitive
+;; entries until the next define-module. Bootstrappers use this to
+;; selectively include primitive groups.
 ;; ==========================================================================
 
 
 ;; --------------------------------------------------------------------------
-;; Arithmetic
+;; Core — Arithmetic
 ;; --------------------------------------------------------------------------
 
+(define-module :core.arithmetic)
+
 (define-primitive "+"
   :params (&rest args)
   :returns "number"
@@ -115,9 +121,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Comparison
+;; Core — Comparison
 ;; --------------------------------------------------------------------------
 
+(define-module :core.comparison)
+
 (define-primitive "="
   :params (a b)
   :returns "boolean"
@@ -151,9 +159,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Predicates
+;; Core — Predicates
 ;; --------------------------------------------------------------------------
 
+(define-module :core.predicates)
+
 (define-primitive "odd?"
   :params (n)
   :returns "boolean"
@@ -209,9 +219,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Logic
+;; Core — Logic
 ;; --------------------------------------------------------------------------
 
+(define-module :core.logic)
+
 (define-primitive "not"
   :params (x)
   :returns "boolean"
@@ -219,9 +231,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Strings
+;; Core — Strings
 ;; --------------------------------------------------------------------------
 
+(define-module :core.strings)
+
 (define-primitive "str"
   :params (&rest args)
   :returns "string"
@@ -279,9 +293,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Collections — construction
+;; Core — Collections
 ;; --------------------------------------------------------------------------
 
+(define-module :core.collections)
+
 (define-primitive "list"
   :params (&rest args)
   :returns "list"
@@ -297,11 +313,6 @@
   :returns "list"
   :doc "Integer range [start, end) with optional step.")
 
-
-;; --------------------------------------------------------------------------
-;; Collections — access
-;; --------------------------------------------------------------------------
-
 (define-primitive "get"
   :params (coll key &rest default)
   :returns "any"
@@ -354,9 +365,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Collections — dict operations
+;; Core — Dict operations
 ;; --------------------------------------------------------------------------
 
+(define-module :core.dict)
+
 (define-primitive "keys"
   :params (d)
   :returns "list"
@@ -389,9 +402,11 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Format helpers
+;; Stdlib — Format
 ;; --------------------------------------------------------------------------
 
+(define-module :stdlib.format)
+
 (define-primitive "format-date"
   :params (date-str fmt)
   :returns "string"
@@ -407,11 +422,18 @@
   :returns "number"
   :doc "Parse string to integer with optional default on failure.")
 
+(define-primitive "parse-datetime"
+  :params (s)
+  :returns "string"
+  :doc "Parse datetime string — identity passthrough (returns string or nil).")
+
 
 ;; --------------------------------------------------------------------------
-;; Text helpers
+;; Stdlib — Text
 ;; --------------------------------------------------------------------------
 
+(define-module :stdlib.text)
+
 (define-primitive "pluralize"
   :params (count &rest forms)
   :returns "string"
@@ -429,33 +451,10 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Date & parsing helpers
+;; Stdlib — Style
 ;; --------------------------------------------------------------------------
 
-(define-primitive "parse-datetime"
-  :params (s)
-  :returns "string"
-  :doc "Parse datetime string — identity passthrough (returns string or nil).")
-
-(define-primitive "split-ids"
-  :params (s)
-  :returns "list"
-  :doc "Split comma-separated ID string into list of trimmed non-empty strings.")
-
-
-;; --------------------------------------------------------------------------
-;; Assertions
-;; --------------------------------------------------------------------------
-
-(define-primitive "assert"
-  :params (condition &rest message)
-  :returns "boolean"
-  :doc "Assert condition is truthy; raise error with message if not.")
-
-
-;; --------------------------------------------------------------------------
-;; CSSX — style system primitives
-;; --------------------------------------------------------------------------
+(define-module :stdlib.style)
 
 (define-primitive "css"
   :params (&rest atoms)
@@ -467,3 +466,15 @@
   :params (&rest styles)
   :returns "style-value"
   :doc "Merge multiple StyleValues into one combined StyleValue.")
+
+
+;; --------------------------------------------------------------------------
+;; Stdlib — Debug
+;; --------------------------------------------------------------------------
+
+(define-module :stdlib.debug)
+
+(define-primitive "assert"
+  :params (condition &rest message)
+  :returns "boolean"
+  :doc "Assert condition is truthy; raise error with message if not.")