Content-addressed computation: freeze → hash → CID → thaw

Hash frozen SX to a content identifier (djb2 → hex). Same state
always produces the same CID. Store by CID, retrieve by CID.

- content-hash: djb2 hash of SX text → hex string
- content-put/get: in-memory content store
- freeze-to-cid: freeze scope → store → return CID
- thaw-from-cid: look up CID → thaw signals
- char-code-at / to-hex primitives for both platforms
- Live demo: counter + name widget, content-address button,
  CID display, restore from CID input, CID history

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

shared/sx/ref/cek.sx

@@ -1129,3 +1129,50 @@
           (cek-thaw-scope (get frozen "name") frozen))))))
 
 
+
+
+;; --------------------------------------------------------------------------
+;; 14. Content-addressed computation
+;; --------------------------------------------------------------------------
+;;
+;; Hash frozen SX to a content identifier. Store and retrieve by CID.
+;; The content IS the address — same SX always produces the same CID.
+;;
+;; Uses an in-memory content store. Applications can persist to
+;; localStorage or IPFS by providing their own store backend.
+
+(define content-store (dict))
+
+(define content-hash :effects []
+  (fn (sx-text)
+    ;; djb2 hash → hex string. Simple, deterministic, fast.
+    ;; Real deployment would use SHA-256 / multihash.
+    (let ((hash 5381))
+      (for-each (fn (i)
+        (set! hash (mod (+ (* hash 33) (char-code-at sx-text i)) 4294967296)))
+        (range 0 (len sx-text)))
+      (to-hex hash))))
+
+(define content-put :effects [mutation]
+  (fn (sx-text)
+    (let ((cid (content-hash sx-text)))
+      (dict-set! content-store cid sx-text)
+      cid)))
+
+(define content-get :effects []
+  (fn (cid)
+    (get content-store cid)))
+
+;; Freeze a scope → store → return CID
+(define freeze-to-cid :effects [mutation]
+  (fn (scope-name)
+    (let ((sx-text (freeze-to-sx scope-name)))
+      (content-put sx-text))))
+
+;; Thaw from CID → look up → restore
+(define thaw-from-cid :effects [mutation]
+  (fn (cid)
+    (let ((sx-text (content-get cid)))
+      (when sx-text
+        (thaw-from-sx sx-text)
+        true))))

shared/sx/ref/platform_js.py

@@ -1532,6 +1532,10 @@ CEK_FIXUPS_JS = '''
   PRIMITIVES["is-html-tag?"] = function(n) { return HTML_TAGS.indexOf(n) >= 0; };
   PRIMITIVES["make-env"] = function() { return merge(componentEnv, PRIMITIVES); };
 
+  // String/number utilities for content addressing
+  PRIMITIVES["char-code-at"] = function(s, i) { return s.charCodeAt(i); };
+  PRIMITIVES["to-hex"] = function(n) { return (n >>> 0).toString(16); };
+
   // localStorage — defined here (before boot) so islands can use at hydration
   PRIMITIVES["local-storage-get"] = function(key) {
     try { var v = localStorage.getItem(key); return v === null ? NIL : v; }

shared/sx/ref/platform_py.py

@@ -1020,6 +1020,10 @@ number_p = PRIMITIVES["number?"]
 string_p = PRIMITIVES["string?"]
 list_p = PRIMITIVES["list?"]
 dissoc = PRIMITIVES["dissoc"]
+PRIMITIVES["char-code-at"] = lambda s, i: ord(s[int(i)]) if 0 <= int(i) < len(s) else 0
+PRIMITIVES["to-hex"] = lambda n: hex(int(n) & 0xFFFFFFFF)[2:]
+char_code_at = PRIMITIVES["char-code-at"]
+to_hex = PRIMITIVES["to-hex"]
 index_of = PRIMITIVES["index-of"]
 lower = PRIMITIVES["lower"]
 char_from_code = PRIMITIVES["char-from-code"]

shared/sx/ref/sx_ref.py

@@ -940,6 +940,10 @@ number_p = PRIMITIVES["number?"]
 string_p = PRIMITIVES["string?"]
 list_p = PRIMITIVES["list?"]
 dissoc = PRIMITIVES["dissoc"]
+PRIMITIVES["char-code-at"] = lambda s, i: ord(s[int(i)]) if 0 <= int(i) < len(s) else 0
+PRIMITIVES["to-hex"] = lambda n: hex(int(n) & 0xFFFFFFFF)[2:]
+char_code_at = PRIMITIVES["char-code-at"]
+to_hex = PRIMITIVES["to-hex"]
 index_of = PRIMITIVES["index-of"]
 lower = PRIMITIVES["lower"]
 char_from_code = PRIMITIVES["char-from-code"]
@@ -4659,6 +4663,40 @@ def thaw_from_sx(sx_text):
         return cek_thaw_scope(get(frozen, 'name'), frozen)
     return NIL
 
+# content-store
+content_store = {}
+
+# content-hash
+def content_hash(sx_text):
+    _cells = {}
+    _cells['hash'] = 5381
+    for i in range(0, len(sx_text)):
+        _cells['hash'] = (((_cells['hash'] * 33) + char_code_at(sx_text, i)) % 4294967296)
+    return to_hex(_cells['hash'])
+
+# content-put
+def content_put(sx_text):
+    cid = content_hash(sx_text)
+    content_store[cid] = sx_text
+    return cid
+
+# content-get
+def content_get(cid):
+    return get(content_store, cid)
+
+# freeze-to-cid
+def freeze_to_cid(scope_name):
+    sx_text = freeze_to_sx(scope_name)
+    return content_put(sx_text)
+
+# thaw-from-cid
+def thaw_from_cid(cid):
+    sx_text = content_get(cid)
+    if sx_truthy(sx_text):
+        thaw_from_sx(sx_text)
+        return True
+    return NIL
+
 
 # === Transpiled from signals (reactive signal runtime) ===