reflective: extract env.sx + migrate Kernel — 322 tests green

Phase 1 of the lib-guest-reflective extraction plan.

lib/guest/reflective/env.sx — canonical wire shape
{:refl-tag :env :bindings DICT :parent ENV-OR-NIL} with mutable
defaults (dict-set!), plus *-with adapter-cfg variants for consumers
with their own shape (modelled after lib/guest/match.sx). 13 forms,
~5 KB.

lib/kernel/eval.sx — env block collapses from ~30 lines to 6 thin
wrappers (kernel-env? = refl-env?, etc.). No semantic change; envs
now carry :refl-tag :env instead of :knl-tag :env. All 322 Kernel
tests pass unchanged across 7 suites (parse 62, eval 36, vau 38,
standard 127, encap 19, hygiene 26, metacircular 14).

Next: Phase 2 — Tcl adapter cfg in lib/tcl/runtime.sx using
refl-env-lookup-with against the existing :level/:locals/:parent
frame shape.

lib/guest/reflective/env.sx

@@ -0,0 +1,138 @@
+;; lib/guest/reflective/env.sx — first-class environment kit.
+;;
+;; Extracted from Kernel-on-SX (lib/kernel/eval.sx) when Tcl's
+;; uplevel/upvar machinery (lib/tcl/runtime.sx) materialised as a
+;; second consumer needing the same scope-chain semantics.
+;;
+;; Canonical wire shape
+;; --------------------
+;;   {:refl-tag :env :bindings DICT :parent ENV-OR-NIL}
+;;
+;;   - :bindings is a mutable SX dict keyed by symbol name.
+;;   - :parent is either another env or nil (root).
+;;   - Lookup walks the parent chain until a hit or nil.
+;;   - Default cfg uses dict-set! to mutate bindings in place.
+;;
+;; Consumers with their own shape (e.g., Tcl's {:level :locals :parent})
+;; pass an adapter cfg dict — same trick as lib/guest/match.sx's cfg
+;; for unification over guest-specific term shapes.
+;;
+;; Adapter cfg keys
+;; ----------------
+;;   :bindings-of  — fn (scope) → DICT
+;;   :parent-of    — fn (scope) → SCOPE-OR-NIL
+;;   :extend       — fn (scope) → SCOPE         (push a fresh child)
+;;   :bind!        — fn (scope name val) → scope (functional or mutable)
+;;   :env?         — fn (v) → bool              (predicate; cheap shape check)
+;;
+;; Public API — canonical shape, mutable, raises on miss
+;;
+;;   (refl-make-env)
+;;   (refl-extend-env PARENT)
+;;   (refl-env? V)
+;;   (refl-env-bind! ENV NAME VAL)
+;;   (refl-env-has? ENV NAME)
+;;   (refl-env-lookup ENV NAME)
+;;   (refl-env-lookup-or-nil ENV NAME)
+;;
+;; Public API — adapter-cfg, any shape
+;;
+;;   (refl-env-extend-with CFG SCOPE)
+;;   (refl-env-bind!-with  CFG SCOPE NAME VAL)
+;;   (refl-env-has?-with   CFG SCOPE NAME)
+;;   (refl-env-lookup-with CFG SCOPE NAME)
+;;   (refl-env-lookup-or-nil-with CFG SCOPE NAME)
+;;
+;;   (refl-canonical-cfg) — the default cfg, exposed so consumers
+;;                          can compare or extend it.
+
+;; ── Canonical-shape predicates and constructors ─────────────────
+
+(define refl-env? (fn (v) (and (dict? v) (= (get v :refl-tag) :env))))
+
+(define refl-make-env (fn () {:parent nil :refl-tag :env :bindings {}}))
+
+(define refl-extend-env (fn (parent) {:parent parent :refl-tag :env :bindings {}}))
+
+(define
+  refl-env-bind!
+  (fn (env name val) (dict-set! (get env :bindings) name val) env))
+
+(define
+  refl-env-has?
+  (fn
+    (env name)
+    (cond
+      ((nil? env) false)
+      ((not (refl-env? env)) false)
+      ((dict-has? (get env :bindings) name) true)
+      (:else (refl-env-has? (get env :parent) name)))))
+
+(define
+  refl-env-lookup
+  (fn
+    (env name)
+    (cond
+      ((nil? env) (error (str "refl-env-lookup: unbound symbol: " name)))
+      ((not (refl-env? env))
+        (error (str "refl-env-lookup: corrupt env: " env)))
+      ((dict-has? (get env :bindings) name) (get (get env :bindings) name))
+      (:else (refl-env-lookup (get env :parent) name)))))
+
+(define
+  refl-env-lookup-or-nil
+  (fn
+    (env name)
+    (cond
+      ((nil? env) nil)
+      ((not (refl-env? env)) nil)
+      ((dict-has? (get env :bindings) name) (get (get env :bindings) name))
+      (:else (refl-env-lookup-or-nil (get env :parent) name)))))
+
+;; ── Adapter-cfg variants — any wire shape ───────────────────────
+
+(define refl-env-extend-with (fn (cfg scope) ((get cfg :extend) scope)))
+
+(define
+  refl-env-bind!-with
+  (fn (cfg scope name val) ((get cfg :bind!) scope name val)))
+
+(define
+  refl-env-has?-with
+  (fn
+    (cfg scope name)
+    (cond
+      ((nil? scope) false)
+      ((not ((get cfg :env?) scope)) false)
+      ((dict-has? ((get cfg :bindings-of) scope) name) true)
+      (:else (refl-env-has?-with cfg ((get cfg :parent-of) scope) name)))))
+
+(define
+  refl-env-lookup-with
+  (fn
+    (cfg scope name)
+    (cond
+      ((nil? scope) (error (str "refl-env-lookup: unbound symbol: " name)))
+      ((not ((get cfg :env?) scope))
+        (error (str "refl-env-lookup: corrupt scope: " scope)))
+      ((dict-has? ((get cfg :bindings-of) scope) name)
+        (get ((get cfg :bindings-of) scope) name))
+      (:else (refl-env-lookup-with cfg ((get cfg :parent-of) scope) name)))))
+
+(define
+  refl-env-lookup-or-nil-with
+  (fn
+    (cfg scope name)
+    (cond
+      ((nil? scope) nil)
+      ((not ((get cfg :env?) scope)) nil)
+      ((dict-has? ((get cfg :bindings-of) scope) name)
+        (get ((get cfg :bindings-of) scope) name))
+      (:else
+        (refl-env-lookup-or-nil-with cfg ((get cfg :parent-of) scope) name)))))
+
+;; ── Default canonical cfg ───────────────────────────────────────
+;; Exposed so consumers can use it explicitly, compose with it, or
+;; check adapter-correctness against the canonical implementation.
+
+(define refl-canonical-cfg {:bind! (fn (e n v) (refl-env-bind! e n v)) :parent-of (fn (e) (get e :parent)) :env? (fn (v) (refl-env? v)) :bindings-of (fn (e) (get e :bindings)) :extend (fn (e) (refl-extend-env e))})

lib/kernel/eval.sx

@@ -7,9 +7,11 @@
 ;;
 ;; Tagged values
 ;; -------------
-;;   {:knl-tag :env :bindings DICT :parent PARENT-OR-NIL}
+;;   {:refl-tag :env :bindings DICT :parent PARENT-OR-NIL}
 ;;     A first-class Kernel environment. Bindings is a mutable SX dict
-;;     keyed by symbol name; parent walks up the lookup chain.
+;;     keyed by symbol name; parent walks up the lookup chain. Shape
+;;     and operations are inherited from lib/guest/reflective/env.sx
+;;     (canonical wire shape) — Kernel-side names are thin wrappers.
 ;;
 ;;   {:knl-tag :operative :impl FN}
 ;;     Primitive operative. FN receives (args dyn-env) — args are the
@@ -42,38 +44,16 @@
 ;;
 ;; Consumes: lib/kernel/parser.sx (kernel-string?, kernel-string-value)
 
-;; ── Environments — first-class, pure-SX (binding dict + parent) ──
+;; ── Environments — delegated to lib/guest/reflective/env.sx ──────
+;; The env values themselves now carry `:refl-tag :env` (shared with the
+;; reflective kit). Kernel's API names stay; bodies are thin wrappers.
 
-(define kernel-env? (fn (v) (and (dict? v) (= (get v :knl-tag) :env))))
-
-(define kernel-make-env (fn () {:parent nil :knl-tag :env :bindings {}}))
-
-(define kernel-extend-env (fn (parent) {:parent parent :knl-tag :env :bindings {}}))
-
-(define
-  kernel-env-bind!
-  (fn (env name val) (dict-set! (get env :bindings) name val) val))
-
-(define
-  kernel-env-has?
-  (fn
-    (env name)
-    (cond
-      ((nil? env) false)
-      ((not (kernel-env? env)) false)
-      ((dict-has? (get env :bindings) name) true)
-      (:else (kernel-env-has? (get env :parent) name)))))
-
-(define
-  kernel-env-lookup
-  (fn
-    (env name)
-    (cond
-      ((nil? env) (error (str "kernel-eval: unbound symbol: " name)))
-      ((not (kernel-env? env))
-        (error (str "kernel-eval: corrupt env: " env)))
-      ((dict-has? (get env :bindings) name) (get (get env :bindings) name))
-      (:else (kernel-env-lookup (get env :parent) name)))))
+(define kernel-env?        refl-env?)
+(define kernel-make-env    refl-make-env)
+(define kernel-extend-env  refl-extend-env)
+(define kernel-env-bind!   refl-env-bind!)
+(define kernel-env-has?    refl-env-has?)
+(define kernel-env-lookup  refl-env-lookup)
 
 ;; ── Tagged-value constructors and predicates ─────────────────────