Fix all 9 spec test failures: Env scope chain, IO detection, offline mutation

- env.py: Add MergedEnv with dual-parent lookup (primary for set!,
  secondary for reads), add dict-compat methods to Env
- platform_py.py: make_lambda stores env reference (no copy), env_merge
  uses MergedEnv for proper set! propagation, ancestor detection prevents
  unbounded chains in TCO recursion, sf_set_bang walks scope chain
- types.py: Component/Island io_refs defaults to None (not computed)
  instead of empty set, so component-pure? falls through to scan
- run.py: Test env uses Env class, mock execute-action calls SX lambdas
  via _call_sx instead of direct Python call

Spec tests: 320/320 (was 311/320)

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

shared/sx/env.py

@@ -20,7 +20,7 @@ class Env:
         bindings: dict[str, Any] | None = None,
         parent: Env | None = None,
     ):
-        self._bindings: dict[str, Any] = bindings or {}
+        self._bindings: dict[str, Any] = {} if bindings is None else bindings
         self._parent = parent
 
     # -- lookup -------------------------------------------------------------
@@ -46,12 +46,30 @@ class Env:
     def __getitem__(self, name: str) -> Any:
         return self.lookup(name)
 
+    def __setitem__(self, name: str, value: Any) -> None:
+        """Set *name* in the **current** scope (like ``define``)."""
+        self._bindings[name] = value
+
     def get(self, name: str, default: Any = None) -> Any:
         try:
             return self.lookup(name)
         except KeyError:
             return default
 
+    def update(self, other: dict[str, Any] | Env) -> None:
+        """Merge *other*'s bindings into the **current** scope."""
+        if isinstance(other, Env):
+            self._bindings.update(other._bindings)
+        else:
+            self._bindings.update(other)
+
+    def keys(self):
+        """All keys visible from this scope (current + parents)."""
+        return self.to_dict().keys()
+
+    def __iter__(self):
+        return iter(self.to_dict())
+
     # -- mutation -----------------------------------------------------------
 
     def define(self, name: str, value: Any) -> None:
@@ -74,7 +92,7 @@ class Env:
 
     def extend(self, bindings: dict[str, Any] | None = None) -> Env:
         """Return a child environment."""
-        return Env(bindings or {}, parent=self)
+        return Env({} if bindings is None else bindings, parent=self)
 
     # -- conversion ---------------------------------------------------------
 
@@ -95,3 +113,58 @@ class Env:
             depth += 1
             p = p._parent
         return f"<Env depth={depth} keys={keys}>"
+
+
+class MergedEnv(Env):
+    """Env with two parent chains: primary (closure) and secondary (caller).
+
+    Reads walk: local bindings → primary chain → secondary chain.
+    set! walks: local bindings → primary chain (skips secondary).
+    This allows set! to modify variables in the defining scope (closure)
+    without being confused by overlay copies from the calling scope.
+    """
+
+    __slots__ = ("_secondary",)
+
+    def __init__(
+        self,
+        bindings: dict[str, Any] | None = None,
+        primary: Env | None = None,
+        secondary: Env | None = None,
+    ):
+        super().__init__(bindings, parent=primary)
+        self._secondary = secondary
+
+    def lookup(self, name: str) -> Any:
+        try:
+            return super().lookup(name)
+        except KeyError:
+            if self._secondary is not None:
+                return self._secondary.lookup(name)
+            raise
+
+    def __contains__(self, name: str) -> bool:
+        if super().__contains__(name):
+            return True
+        if self._secondary is not None:
+            return name in self._secondary
+        return False
+
+    def get(self, name: str, default: Any = None) -> Any:
+        try:
+            return self.lookup(name)
+        except KeyError:
+            return default
+
+    def to_dict(self) -> dict[str, Any]:
+        if self._secondary is not None:
+            d = self._secondary.to_dict()
+        else:
+            d = {}
+        if self._parent is not None:
+            d.update(self._parent.to_dict())
+        d.update(self._bindings)
+        return d
+
+    def extend(self, bindings: dict[str, Any] | None = None) -> Env:
+        return Env(bindings or {}, parent=self)

shared/sx/ref/platform_py.py

@@ -57,6 +57,7 @@ from shared.sx.types import (
     HandlerDef, QueryDef, ActionDef, PageDef, _ShiftSignal,
 )
 from shared.sx.parser import SxExpr
+from shared.sx.env import Env as _Env, MergedEnv as _MergedEnv
 '''
 
 # ---------------------------------------------------------------------------
@@ -195,8 +196,15 @@ def make_keyword(n):
     return Keyword(n)
 
 
+def _ensure_env(env):
+    """Wrap plain dict in Env if needed."""
+    if isinstance(env, _Env):
+        return env
+    return _Env(env if isinstance(env, dict) else {})
+
+
 def make_lambda(params, body, env):
-    return Lambda(params=list(params), body=body, closure=dict(env))
+    return Lambda(params=list(params), body=body, closure=_ensure_env(env))
 
 
 def make_component(name, params, has_children, body, env, affinity="auto"):
@@ -490,13 +498,26 @@ def env_set(env, name, val):
 
 
 def env_extend(env):
-    return dict(env)
+    return _ensure_env(env).extend()
 
 
 def env_merge(base, overlay):
-    result = dict(base)
-    result.update(overlay)
-    return result
+    base = _ensure_env(base)
+    overlay = _ensure_env(overlay)
+    if base is overlay:
+        # Same env — just extend with empty local scope for params
+        return base.extend()
+    # Check if base is an ancestor of overlay — if so, no need to merge
+    # (common for self-recursive calls where closure == caller's ancestor)
+    p = overlay
+    depth = 0
+    while p is not None and depth < 100:
+        if p is base:
+            return base.extend()
+        p = getattr(p, '_parent', None)
+        depth += 1
+    # MergedEnv: reads walk base then overlay; set! walks base only
+    return _MergedEnv({}, primary=base, secondary=overlay)
 
 
 def dict_set(d, k, v):
@@ -1022,8 +1043,10 @@ PLATFORM_DEPS_PY = (
     '    return list(classes)\n'
     '\n'
     'def component_io_refs(c):\n'
-    '    """Return cached IO refs list for a component (may be empty)."""\n'
-    '    return list(c.io_refs) if hasattr(c, "io_refs") and c.io_refs else []\n'
+    '    """Return cached IO refs list, or NIL if not yet computed."""\n'
+    '    if not hasattr(c, "io_refs") or c.io_refs is None:\n'
+    '        return NIL\n'
+    '    return list(c.io_refs)\n'
     '\n'
     'def component_set_io_refs(c, refs):\n'
     '    """Cache IO refs on a component."""\n'
@@ -1255,6 +1278,20 @@ def _wrap_aser_outputs():
         return SxExpr(result) if isinstance(result, str) else result
     aser_call = _aser_call_wrapped
     aser_fragment = _aser_fragment_wrapped
+
+
+# Override sf_set_bang to walk the Env scope chain so that (set! var val)
+# updates the variable in its defining scope, not just the local copy.
+def sf_set_bang(args, env):
+    name = symbol_name(first(args))
+    value = trampoline(eval_expr(nth(args, 1), env))
+    env = _ensure_env(env)
+    try:
+        env.set(name, value)
+    except KeyError:
+        # Not found in chain — define locally (matches prior behavior)
+        env[name] = value
+    return value
 '''
 
 # ---------------------------------------------------------------------------
@@ -1349,7 +1386,9 @@ def public_api_py(has_html: bool, has_sx: bool, has_deps: bool = False) -> str:
         'def evaluate(expr, env=None):',
         '    """Evaluate expr in env and return the result."""',
         '    if env is None:',
-        '        env = {}',
+        '        env = _Env()',
+        '    elif isinstance(env, dict):',
+        '        env = _Env(env)',
         '    result = eval_expr(expr, env)',
         '    while is_thunk(result):',
         '        result = eval_expr(thunk_expr(result), thunk_env(result))',
@@ -1369,8 +1408,8 @@ def public_api_py(has_html: bool, has_sx: bool, has_deps: bool = False) -> str:
         '',
         '',
         'def make_env(**kwargs):',
-        '    """Create an environment dict with initial bindings."""',
-        '    return dict(kwargs)',
+        '    """Create an environment with initial bindings."""',
+        '    return _Env(dict(kwargs))',
     ])
     return '\n'.join(lines)
 

shared/sx/ref/sx_ref.py

@@ -21,6 +21,7 @@ from shared.sx.types import (
     HandlerDef, QueryDef, ActionDef, PageDef, _ShiftSignal,
 )
 from shared.sx.parser import SxExpr
+from shared.sx.env import Env as _Env, MergedEnv as _MergedEnv
 
 
 # =========================================================================
@@ -154,8 +155,15 @@ def make_keyword(n):
     return Keyword(n)
 
 
+def _ensure_env(env):
+    """Wrap plain dict in Env if needed."""
+    if isinstance(env, _Env):
+        return env
+    return _Env(env if isinstance(env, dict) else {})
+
+
 def make_lambda(params, body, env):
-    return Lambda(params=list(params), body=body, closure=dict(env))
+    return Lambda(params=list(params), body=body, closure=_ensure_env(env))
 
 
 def make_component(name, params, has_children, body, env, affinity="auto"):
@@ -449,13 +457,26 @@ def env_set(env, name, val):
 
 
 def env_extend(env):
-    return dict(env)
+    return _ensure_env(env).extend()
 
 
 def env_merge(base, overlay):
-    result = dict(base)
-    result.update(overlay)
-    return result
+    base = _ensure_env(base)
+    overlay = _ensure_env(overlay)
+    if base is overlay:
+        # Same env — just extend with empty local scope for params
+        return base.extend()
+    # Check if base is an ancestor of overlay — if so, no need to merge
+    # (common for self-recursive calls where closure == caller's ancestor)
+    p = overlay
+    depth = 0
+    while p is not None and depth < 100:
+        if p is base:
+            return base.extend()
+        p = getattr(p, '_parent', None)
+        depth += 1
+    # MergedEnv: reads walk base then overlay; set! walks base only
+    return _MergedEnv({}, primary=base, secondary=overlay)
 
 
 def dict_set(d, k, v):
@@ -937,8 +958,10 @@ def scan_css_classes(source):
     return list(classes)
 
 def component_io_refs(c):
-    """Return cached IO refs list for a component (may be empty)."""
-    return list(c.io_refs) if hasattr(c, "io_refs") and c.io_refs else []
+    """Return cached IO refs list, or NIL if not yet computed."""
+    if not hasattr(c, "io_refs") or c.io_refs is None:
+        return NIL
+    return list(c.io_refs)
 
 def component_set_io_refs(c, refs):
     """Cache IO refs on a component."""
@@ -2985,6 +3008,20 @@ def _wrap_aser_outputs():
     aser_fragment = _aser_fragment_wrapped
 
 
+# Override sf_set_bang to walk the Env scope chain so that (set! var val)
+# updates the variable in its defining scope, not just the local copy.
+def sf_set_bang(args, env):
+    name = symbol_name(first(args))
+    value = trampoline(eval_expr(nth(args, 1), env))
+    env = _ensure_env(env)
+    try:
+        env.set(name, value)
+    except KeyError:
+        # Not found in chain — define locally (matches prior behavior)
+        env[name] = value
+    return value
+
+
 # =========================================================================
 # Public API
 # =========================================================================
@@ -2998,7 +3035,9 @@ _setup_html_adapter()
 def evaluate(expr, env=None):
     """Evaluate expr in env and return the result."""
     if env is None:
-        env = {}
+        env = _Env()
+    elif isinstance(env, dict):
+        env = _Env(env)
     result = eval_expr(expr, env)
     while is_thunk(result):
         result = eval_expr(thunk_expr(result), thunk_env(result))
@@ -3018,5 +3057,5 @@ def render(expr, env=None):
 
 
 def make_env(**kwargs):
-    """Create an environment dict with initial bindings."""
-    return dict(kwargs)
+    """Create an environment with initial bindings."""
+    return _Env(dict(kwargs))

shared/sx/tests/run.py

@@ -281,7 +281,9 @@ def eval_file(filename, env):
 
 
 # --- Build env ---
-env = {
+from shared.sx.env import Env as _Env
+
+env = _Env({
     "try-call": try_call,
     "report-pass": report_pass,
     "report-fail": report_fail,
@@ -330,7 +332,7 @@ env = {
     "component-body": lambda c: getattr(c, 'body', NIL),
     "component-closure": lambda c: dict(getattr(c, 'closure', {})),
     "component-has-children?": lambda c: getattr(c, 'has_children', False),
-}
+})
 
 
 def _call_sx(fn, args, caller_env):
@@ -496,7 +498,7 @@ def _load_orchestration(env):
 
     def _mock_execute_action(action, payload, on_success, on_error):
         """Mock: immediately calls on_success with payload as 'server truth'."""
-        on_success(payload)
+        _call_sx(on_success, [payload], env)
         return NIL
 
     def _dict_delete(d, k):

shared/sx/types.py

@@ -168,7 +168,7 @@ class Component:
     closure: dict[str, Any] = field(default_factory=dict)
     css_classes: set[str] = field(default_factory=set)  # pre-scanned :class values
     deps: set[str] = field(default_factory=set)        # transitive component deps (~names)
-    io_refs: set[str] = field(default_factory=set)     # transitive IO primitive refs
+    io_refs: set[str] | None = None     # transitive IO primitive refs (None = not computed)
     affinity: str = "auto"    # "auto" | "client" | "server"
 
     @property
@@ -208,7 +208,7 @@ class Island:
     closure: dict[str, Any] = field(default_factory=dict)
     css_classes: set[str] = field(default_factory=set)
     deps: set[str] = field(default_factory=set)
-    io_refs: set[str] = field(default_factory=set)
+    io_refs: set[str] | None = None
 
     def __repr__(self):
         return f"<Island ~{self.name}({', '.join(self.params)})>"