self-host: analyzer reaches full conformance parity via hybrid fallback

The Clojure analyzer + Janet back end now pass all 218 conformance cases (vs the
interpreter) through the self-hosted pipeline:
- host contract gains special? (the full special-form/uncompilable set), so the
  analyzer falls back for forms it doesn't compile instead of miscompiling them
  as calls;
- qualified symbol refs that don't resolve to a var (janet/…, Math/…, host
  interop) and tagged literals (#"regex", #inst) and set literals throw
  uncompilable -> interpreter;
- the back end's compile-and-eval is now hybrid: only the compile step is
  guarded, runtime errors propagate.

Still interpreter-routed (coverage to grow next): loop/recur, recur in fn, try,
sets, destructuring.

jolt-core/jolt/analyzer.clj

@@ -100,13 +100,20 @@
 
 (defn- analyze-symbol [ctx form locals]
   (let [nm (h/sym-name form) ns (h/sym-ns form)]
-    (if (and (nil? ns) (contains? locals nm))
-      (ir/local nm)
-      (let [r (h/resolve-global ctx form)]
+    (cond
+      ;; local (only unqualified)
+      (and (nil? ns) (contains? locals nm)) (ir/local nm)
+      ;; qualified: must resolve to a var, else interpret (handles janet/…,
+      ;; Math/…, and any host interop the back end doesn't model).
+      ns (let [r (h/resolve-global ctx form)]
+           (if (= :var (:kind r))
+             (ir/var-ref (:ns r) (:name r))
+             (uncompilable (str "qualified ref " ns "/" nm))))
+      :else (let [r (h/resolve-global ctx form)]
               (case (:kind r)
                 :var (ir/var-ref (:ns r) (:name r))
                 :host (ir/host-ref (:name r))
-          ;; unresolved: a forward reference in the current ns; resolved at call time
+                ;; unresolved: forward reference in the current ns (resolved at call time)
                 (ir/var-ref (h/current-ns ctx) nm))))))
 
 (defn- analyze-list [ctx form locals]
@@ -119,6 +126,9 @@
         (cond
           (and hname (not shadowed) (contains? handled hname))
             (analyze-special ctx hname items locals)
+          ;; A special form the analyzer doesn't compile -> interpreter.
+          (and hname (not shadowed) (h/special? hname))
+            (uncompilable (str "special form " hname))
           (and (h/sym? head) (not shadowed) (h/macro? ctx head))
             (analyze ctx (h/expand-1 ctx form) locals)
           :else
@@ -136,6 +146,8 @@
      (h/map? form) (ir/map-node (mapv (fn [p] [(analyze ctx (first p) locals)
                                                (analyze ctx (second p) locals)])
                                       (h/map-pairs form)))
-     (h/set? form) (ir/set-node (mapv #(analyze ctx % locals) (h/set-items form)))
+     (h/set? form) (uncompilable "set literal")
      (h/list? form) (analyze-list ctx form locals)
-     :else (ir/const form))))
+     ;; Anything else (tagged literals like #"regex"/#inst, unknown shapes) is
+     ;; host-specific or not a value the back end can embed — interpret it.
+     :else (uncompilable "unsupported form"))))

src/jolt/backend.janet

@@ -136,6 +136,12 @@
   ((var-get av) ctx form))
 
 (defn compile-and-eval
-  "Self-hosted compile path: analyze (portable Clojure) -> IR -> Janet -> eval."
+  "Self-hosted compile path: analyze (portable Clojure) -> IR -> Janet -> eval.
+  Hybrid: only the compile step (analyze+emit) is guarded — a form the analyzer
+  can't handle throws and falls back to the interpreter; runtime errors in
+  compiled code propagate (no double-eval, no hidden errors)."
   [ctx form]
-  (eval (emit-ir ctx (analyze-form ctx form)) (comp/ctx-janet-env ctx)))
+  (def compiled (protect (emit-ir ctx (analyze-form ctx form))))
+  (if (compiled 0)
+    (eval (compiled 1) (comp/ctx-janet-env ctx))
+    (eval-form ctx @{} form)))

src/jolt/host_iface.janet

@@ -51,6 +51,29 @@
 # Compile-time environment
 # ---------------------------------------------------------------------------
 
+# Names the analyzer must NOT treat as a function call: interpreter special forms
+# plus definitional/host macros the compiler doesn't lower. The analyzer handles
+# a subset (quote/if/do/def/fn*/let*/loop*/recur/throw/try) and falls back to the
+# interpreter for the rest. Kept in sync with evaluator/special-symbol? and
+# compiler/uncompilable-heads.
+(def- special-names
+  (let [t @{}]
+    (each n ["quote" "syntax-quote" "unquote" "unquote-splicing" "do" "if" "def"
+             "defmacro" "fn*" "let*" "loop*" "recur" "throw" "try" "set!" "var"
+             "locking" "eval" "instance?" "defmulti" "defmethod" "deftype" "new"
+             "." "var-get" "var-set" "var?" "alter-var-root" "find-var" "intern"
+             "alter-meta!" "reset-meta!" "disj" "set?" "satisfies?"
+             "protocol-dispatch" "register-method" "make-reified" "prefer-method"
+             "remove-method" "remove-all-methods" "get-method" "methods"
+             "read-string" "macroexpand-1" "defonce" "ns" "in-ns" "require"
+             "import" "use" "refer" "defrecord" "defprotocol" "definterface"
+             "reify" "proxy" "extend-type" "extend-protocol" "extend" "gen-class"
+             "monitor-enter" "monitor-exit" "binding" "letfn"]
+      (put t n true))
+    t))
+
+(defn h-special? [name] (if (get special-names name) true false))
+
 (defn h-current-ns [ctx] (ctx-current-ns ctx))
 
 (defn h-macro? [ctx sym]
@@ -92,8 +115,8 @@
    "list?" h-list? "vector?" h-vector? "map?" h-map? "set?" h-set? "char?" h-char?
    "literal?" h-literal? "elements" h-elements "vector-items" h-vector-items
    "map-pairs" h-map-pairs "set-items" h-set-items
-   "current-ns" h-current-ns "macro?" h-macro? "expand-1" h-expand-1
-   "resolve-global" h-resolve-global "intern!" h-intern!})
+   "special?" h-special? "current-ns" h-current-ns "macro?" h-macro?
+   "expand-1" h-expand-1 "resolve-global" h-resolve-global "intern!" h-intern!})
 
 (defn install! [ctx]
   (def ns (ctx-find-ns ctx "jolt.host"))