Unify scoped effects: scope as general primitive, provide as sugar

- Add `scope` special form to eval.sx: (scope name body...) or
  (scope name :value v body...) — general dynamic scope primitive
- `provide` becomes sugar: (provide name value body...) calls scope
- Rename provide-push!/provide-pop! to scope-push!/scope-pop! throughout
  all adapters (async, dom, html, sx) and platform implementations
- Update boundary.sx: Tier 5 now "Scoped effects" with scope-push!/
  scope-pop! as primary, provide-push!/provide-pop! as aliases
- Add scope form handling to async adapter and aser wire format
- Update sx-browser.js, sx_ref.py (bootstrapped output)
- Add scopes.sx docs page, update provide/spreads/demo docs
- Update nav-data, page-functions, docs page definitions

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

sx/sx/plans/scoped-effects.sx

@@ -340,24 +340,27 @@
       (p "The path from current SX to the scope primitive follows the existing plan "
          "and adds two phases:")
 
-      (~docs/subsection :title "Phase 1: provide/context/emit! (immediate)"
-        (p "Already planned. Implement render-time dynamic scope. Four primitives: "
+      (~docs/subsection :title "Phase 1: provide/context/emit! ✓"
+        (p (strong "Complete. ") "Render-time dynamic scope. Four primitives: "
            (code "provide") " (special form), " (code "context") ", " (code "emit!") ", "
-           (code "emitted") ". Platform provides " (code "provide-push!/provide-pop!") ".")
-        (p "This is " (code "scope") " with " (code ":propagation :render") " only. "
-           "No change to islands or lakes. Pure addition.")
-        (p (strong "Delivers: ") "render-time context, scoped accumulation, "
-           "spread and collect reimplemented as sugar over provide/emit."))
+           (code "emitted") ". Platform provides " (code "scope-push!/scope-pop!") ". "
+           "Spreads reimplemented on provide/emit!.")
+        (p "See "
+           (a :href "/sx/(geography.(provide))" :class "text-violet-600 hover:underline" "provide article")
+           " and "
+           (a :href "/sx/(geography.(spreads))" :class "text-violet-600 hover:underline" "spreads article")
+           "."))
 
-      (~docs/subsection :title "Phase 2: scope as the common form (next)"
-        (p "Introduce " (code "scope") " as the general form. "
-           (code "provide") " becomes sugar for " (code "(scope ... :propagation :render)") ". "
-           (code "defisland") " becomes sugar for " (code "(scope ... :propagation :reactive)") ". "
-           (code "lake") " becomes sugar for " (code "(scope ... :propagation :morph)") ".")
-        (p "The sugar forms remain — nobody writes " (code "scope") " directly in page code. "
-           "But the evaluator, adapters, and bootstrappers all dispatch through one mechanism.")
-        (p (strong "Delivers: ") "unified internal representation, reactive context (the new cell), "
-           "simplified adapter code (one scope handler instead of three separate paths)."))
+      (~docs/subsection :title "Phase 2: scope as the common form ✓"
+        (p (strong "Complete. ") (code "scope") " is now the general form. "
+           (code "provide") " is sugar for " (code "(scope name :value v body...)") ". "
+           (code "collect!") " creates a lazy root scope with deduplication. "
+           "All adapters use " (code "scope-push!/scope-pop!") " directly.")
+        (p "The unified platform structure:")
+        (~docs/code :code (highlight "_scope_stacks = {}  ;; {name: [{value, emitted: [], dedup: bool}]}" "python"))
+        (p "See "
+           (a :href "/sx/(geography.(scopes))" :class "text-violet-600 hover:underline" "scopes article")
+           "."))
 
       (~docs/subsection :title "Phase 3: effect handlers (future)"
         (p "Make propagation modes extensible. A " (code ":propagation") " value is a "
@@ -437,8 +440,10 @@
          "and composable. It's the last primitive SX needs.")
 
       (~docs/note
-        (p (strong "Status: ") "Phase 1 (" (code "provide/context/emit!") ") is specced and "
-           "ready to build. Phase 2 (" (code "scope") " unification) follows naturally once "
-           "provide is working. Phase 3 (extensible handlers) is the research frontier — "
+        (p (strong "Status: ") "Phase 1 (" (code "provide/context/emit!") ") and "
+           "Phase 2 (" (code "scope") " unification) are complete. "
+           "574 tests pass. All four adapters use " (code "scope-push!/scope-pop!") ". "
+           (code "collect!") " is backed by lazy scopes with dedup. "
+           "Phase 3 (extensible handlers) is the research frontier — "
            "it may turn out that three modes are sufficient, or it may turn out that "
            "user-defined modes unlock something unexpected.")))))