feat: jolt-side java.sql interop + defn/defmacro meta & arity-clause fixes

For the migratus next.jdbc shim (jolt-0z5):
- core.janet: __jdbc-wrap-conn / __jdbc-conn-raw / __jdbc-make-stmt builtins.
  A connection is a tagged wrapper over a jdbc.core conn carrying a clj :exec
  callback so the host Statement.executeBatch runs SQL without a janet->clj call.
- javatime.janet: tagged-methods for :jolt/jdbc-conn (setAutoCommit/isClosed/
  close/getMetaData), :jolt/jdbc-meta (getDatabaseProductName), :jolt/jdbc-stmt
  (addBatch/executeBatch/close); java.sql.Timestamp ctor -> millis.
- evaluator.janet: instance? case for Connection/java.sql.Connection so
  migratus's do-commands runs SQL through its Connection branch.

Two defn/defmacro fixes found loading migratus.core (both rooted in the reader
representing ^{:map} name metadata as a with-meta form, jolt-8w2):
- defmacro special form: unwrap a with-meta name (mirrors def), and handle the
  arity-clause form (defmacro name ([params] body...)) like fn/defn — a params
  vector reads as a tuple, an arity clause as a list (array).
- defn overlay: pass the bare (unwrapped) name to fn while def keeps the meta.

Conformance 335/335 x3 modes.

jolt-core/clojure/core/00-syntax.clj

@@ -341,10 +341,14 @@
 (defmacro defn [fn-name & body]
   (let [body (if (and (seq body) (string? (first body))) (rest body) body)
         body (if (and (seq body) (map? (first body)) (not (symbol? (first body))))
-               (rest body) body)]
+               (rest body) body)
+        ;; ^{:map} metadata on the name reads as a (with-meta sym …) form, not an
+        ;; annotated symbol (jolt-8w2). def attaches the metadata, but fn needs a
+        ;; bare symbol, so unwrap it for the fn name.
+        fn-only-name (if (symbol? fn-name) fn-name (first (rest fn-name)))]
     ;; pass the name through to fn: the compiled fn's janet name carries it,
     ;; so stack traces read app.deep/level3 instead of a gensym (jolt-2o7.1)
-    `(def ~fn-name (fn ~fn-name ~@body))))
+    `(def ~fn-name (fn ~fn-only-name ~@body))))
 
 ;; Jolt doesn't enforce privacy, so defn- is just defn (matching how Clojure's own
 ;; defn- delegates to defn with :private metadata).

src/jolt/core.janet

@@ -1724,6 +1724,26 @@
 # the __write / __pr-str1 host seams; str-render-one stays for core-str.
 (defn core-write [s] (prin s) nil)
 
+(defn core-eprint [s] (eprint s) nil)
+(defn core-eprintf [fmt & args] (eprintf fmt ;args) nil)
+
+# next.jdbc host shims (the db library's next.jdbc compat layer builds on these).
+# A connection is a tagged table wrapping a jdbc.core conn (:raw) plus clj
+# callbacks: :exec runs one SQL string in the transaction (so the janet-side
+# Statement.executeBatch can run SQL without a janet->clj call), :close closes
+# the underlying conn, :product is the JDBC database product name. instance?
+# Connection (evaluator) and the :jolt/jdbc-conn tagged methods (javatime) key
+# off this shape.
+(defn core-jdbc-wrap-conn [raw exec closef product]
+  @{:jolt/type :jolt/jdbc-conn :raw raw :exec exec :close closef
+    :product product :closed @[false]})
+# Robust unwrap: a wrapped conn -> its :raw; anything else passes through (so the
+# next.jdbc fns accept either a wrapped conn or a bare jdbc.core conn/spec).
+(defn core-jdbc-conn-raw [x]
+  (if (and (table? x) (= :jolt/jdbc-conn (get x :jolt/type))) (get x :raw) x))
+(defn core-jdbc-make-stmt [w]
+  @{:jolt/type :jolt/jdbc-stmt :exec (get w :exec) :cmds @[]})
+
 # newline lives in the Clojure collection tier (core/20-coll.clj).
 
 # Clojure 1.11 string->scalar parsers: nil on malformed input, throw on a
@@ -2706,6 +2726,11 @@
     "hash-unordered-coll" core-hash-unordered-coll
     "gensym" gensym
     "__write" core-write
+    "__eprint" core-eprint
+    "__eprintf" core-eprintf
+    "__jdbc-wrap-conn" core-jdbc-wrap-conn
+    "__jdbc-conn-raw" core-jdbc-conn-raw
+    "__jdbc-make-stmt" core-jdbc-make-stmt
     "__pr-str1" core-pr-str1
     "__make-uuid" make-uuid
     "compare" core-compare

src/jolt/evaluator.janet

@@ -1583,6 +1583,11 @@
           "DateTimeFormatter" (and (table? val) (= :jolt/dt-formatter (get val :jolt/type)))
           "URL" (and (table? val) (= :jolt/url (get val :jolt/type)))
           "java.net.URL" (and (table? val) (= :jolt/url (get val :jolt/type)))
+          # next.jdbc host shim: a wrapped jdbc.core connection (core.janet).
+          # migratus's do-commands only runs SQL through its (instance? Connection)
+          # branch, so the wrapped conn must answer true here.
+          "Connection" (and (table? val) (= :jolt/jdbc-conn (get val :jolt/type)))
+          "java.sql.Connection" (and (table? val) (= :jolt/jdbc-conn (get val :jolt/type)))
           # JVM char[] class — (Class/forName "[C"); jolt char arrays are Janet
           # arrays of char structs
           "[C" (and (array? val)
@@ -1793,12 +1798,23 @@
                   (put v :dynamic true))
                 # def returns the var (Clojure semantics); REPL prints #'ns/name
                 v)))
-    "defmacro" (let [name-sym (in form 1)
+    "defmacro" (let [# ^{:map} metadata on the name reads as a (with-meta sym …)
+                     # form (jolt-8w2); unwrap to the bare symbol like def does.
+                     name-sym (unwrap-meta-name (in form 1))
                      rest-form (tuple/slice form 2)
                      # optional docstring
                      has-doc? (and (> (length rest-form) 0) (string? (first rest-form)))
-                     args-form (if has-doc? (in rest-form 1) (first rest-form))
+                     raw-args (if has-doc? (in rest-form 1) (first rest-form))
-                     body (tuple/slice rest-form (if has-doc? 2 1))
+                     raw-body (tuple/slice rest-form (if has-doc? 2 1))
+                     # arity-clause form: (defmacro name ([params] body...)) — like
+                     # fn/defn. In a code form a vector literal is a tuple and a list
+                     # is an array, so a params vector reads as a tuple while an arity
+                     # clause reads as a list (array): unwrap its params + body. Single
+                     # arity only (what real macros use); a multi-arity macro takes the
+                     # first clause.
+                     arity-clause? (array? raw-args)
+                     args-form (if arity-clause? (first raw-args) raw-args)
+                     body (if arity-clause? (tuple/slice raw-args 1) raw-body)
                      param-info (parse-params args-form)
                      fixed-pats (param-info :fixed)
                      rest-pat (param-info :rest)

src/jolt/javatime.janet

@@ -536,7 +536,34 @@
   # Thread stub: getContextClassLoader returns a stub so migratus jar/create code
   # that walks Thread/currentThread doesn't crash.
   (register-tagged-methods! :jolt/thread
-    @{"getContextClassLoader" (fn [self] @{:jolt/type :jolt/classloader})}))
+    @{"getContextClassLoader" (fn [self] @{:jolt/type :jolt/classloader})})
+  # next.jdbc host shims (paired with the __jdbc-* builtins in core.janet and the
+  # instance? Connection case in evaluator.janet). The wrapped connection carries
+  # a clj :exec callback (run one SQL string) and a :close callback.
+  # java.sql.Timestamp: migratus builds (Timestamp. millis) for the applied
+  # column; represent it as the millis number so it stores and sorts directly.
+  (each nm ["Timestamp" "java.sql.Timestamp"]
+    (register-class-ctor! nm (fn [ms] ms)))
+  (register-tagged-methods! :jolt/jdbc-conn
+    @{"setAutoCommit" (fn [self _] self)
+      "isClosed" (fn [self] (get (get self :closed) 0))
+      "close" (fn [self]
+                (unless (get (get self :closed) 0)
+                  ((get self :close))
+                  (put (get self :closed) 0 true))
+                nil)
+      "getMetaData" (fn [self] @{:jolt/type :jolt/jdbc-meta :product (get self :product)})})
+  (register-tagged-methods! :jolt/jdbc-meta
+    @{"getDatabaseProductName" (fn [self] (get self :product))})
+  # Statement batch: addBatch accumulates SQL strings, executeBatch runs each via
+  # the connection's clj :exec callback (which executes inside the transaction).
+  (register-tagged-methods! :jolt/jdbc-stmt
+    @{"addBatch" (fn [self sql] (array/push (get self :cmds) sql) nil)
+      "executeBatch" (fn [self]
+                       (def out @[])
+                       (each c (get self :cmds) (array/push out ((get self :exec) c)))
+                       out)
+      "close" (fn [self] nil)}))
 
 (install!)
 (install-io!)