Implement sx-swap pure tree rewriting and fix handler test infrastructure

Write lib/sx-swap.sx — string-level SX scanner that finds elements by :id
and applies swap operations (innerHTML, outerHTML, beforeend, afterbegin,
beforebegin, afterend, delete, none). Includes OOB extraction via
find-oob-elements/strip-oob/apply-response for out-of-band targeted swaps.

Fix &rest varargs bug in test-handlers.sx helper mock — fn doesn't support
&rest, so change to positional (name a1 a2) with nil defaults. Fix into
branch, add run-handler sx-expr unwrapping.

Add missing primitives to run_tests.ml: scope-peek, callable?, make-sx-expr,
sx-expr-source, sx-expr?, spread?, call-lambda. These unblock aser-based
handler evaluation in tests.

Add algebraic integration tests (test-swap-integration.sx) demonstrating the
sx1 ⊕(mode,target) sx2 = sx3 pattern with real handler execution.

1219 → 1330 passing tests (+111).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/tests/test-handlers.sx

@@ -0,0 +1,681 @@
+(define _mock-form (dict))
+
+(define _mock-args (dict))
+
+(define _mock-state (dict))
+
+(define _mock-body "")
+
+(define _mock-content-type "")
+
+(define _mock-headers (dict))
+
+(define _mock-now "12:00:00")
+
+(define
+  reset-mocks!
+  (fn
+    ()
+    (do
+      (set! _mock-form (dict))
+      (set! _mock-args (dict))
+      (set! _mock-state (dict))
+      (set! _mock-body "")
+      (set! _mock-content-type "")
+      (set! _mock-headers (dict)))))
+
+(define
+  helper
+  (fn
+    (name a1 a2)
+    (cond
+      (= name "request-form")
+      (let
+        ((key (or a1 "")) (default (if (nil? a2) "" a2)))
+        (let ((val (get _mock-form key))) (if (nil? val) default val)))
+      (= name "request-arg")
+      (let
+        ((key (or a1 "")) (default a2))
+        (let ((val (get _mock-args key))) (if (nil? val) default val)))
+      (= name "state-get")
+      (let
+        ((key (or a1 "")) (default a2))
+        (let ((val (get _mock-state key))) (if (nil? val) default val)))
+      (= name "state-set!")
+      (do (set! _mock-state (assoc _mock-state a1 a2)) nil)
+      (= name "now")
+      (if (nil? a1) _mock-now _mock-now)
+      (= name "component-source")
+      (str "(defcomp " a1 " () (div))")
+      (= name "request-json")
+      _mock-body
+      (= name "request-content-type")
+      _mock-content-type
+      (= name "request-form-list")
+      (or (get _mock-form a1) (list))
+      (= name "request-args-all")
+      _mock-args
+      (= name "request-headers-all")
+      _mock-headers
+      (= name "request-form-all")
+      _mock-form
+      (= name "request-header")
+      (or (get _mock-headers a1) a2)
+      (= name "request-file-name")
+      (or (get _mock-form a1) "")
+      (= name "into")
+      (let
+        ((coll (if (nil? a2) a1 a2)))
+        (if
+          (dict? coll)
+          (map (fn (key) (list key (get coll key))) (keys coll))
+          (if (nil? coll) (list) coll)))
+      :else nil)))
+
+(define sleep (fn (ms) nil))
+
+(define set-response-status (fn (code) nil))
+
+(define json-encode (fn (val) (inspect val)))
+
+(define
+  run-handler
+  (fn
+    (hdef)
+    (let
+      ((result (aser (get hdef "body") (get hdef "closure"))))
+      (if
+        (sx-expr? result)
+        (sx-expr-source result)
+        (if (string? result) result (str result))))))
+
+(defsuite
+  "example:click-to-load"
+  (deftest
+    "returns content with timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-click)))
+      (assert-true (contains? result "Content loaded!"))))
+  (deftest
+    "includes mock time"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-click)))
+      (assert-true (contains? result _mock-now))))
+  (deftest
+    "includes OOB code panel"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-click)))
+      (assert-true (contains? result "click-comp")))))
+
+(defsuite
+  "example:form-submission"
+  (deftest
+    "greets by name"
+    (reset-mocks!)
+    (set! _mock-form {:name "Alice"})
+    (let
+      ((result (run-handler handler:ex-form)))
+      (assert-true (contains? result "Alice"))))
+  (deftest
+    "greets stranger when empty"
+    (reset-mocks!)
+    (set! _mock-form {:name ""})
+    (let
+      ((result (run-handler handler:ex-form)))
+      (assert-true (contains? result "stranger"))))
+  (deftest
+    "includes wire format OOB"
+    (reset-mocks!)
+    (set! _mock-form {:name "Bob"})
+    (let
+      ((result (run-handler handler:ex-form)))
+      (assert-true (contains? result "form-wire"))))
+  (deftest
+    "wire shows component call with name"
+    (reset-mocks!)
+    (set! _mock-form {:name "Bob"})
+    (let
+      ((result (run-handler handler:ex-form)))
+      (assert-true (contains? result "Bob")))))
+
+(defsuite
+  "example:polling"
+  (deftest
+    "increments counter from zero"
+    (reset-mocks!)
+    (run-handler handler:ex-poll)
+    (assert-equal 1 (get _mock-state "ex-poll-n")))
+  (deftest
+    "increments counter on second call"
+    (reset-mocks!)
+    (run-handler handler:ex-poll)
+    (run-handler handler:ex-poll)
+    (assert-equal 2 (get _mock-state "ex-poll-n")))
+  (deftest
+    "returns timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-poll)))
+      (assert-true (contains? result _mock-now))))
+  (deftest
+    "returns counter value"
+    (reset-mocks!)
+    (run-handler handler:ex-poll)
+    (let
+      ((result (run-handler handler:ex-poll)))
+      (assert-true (contains? result "2")))))
+
+(defsuite
+  "example:delete-row"
+  (deftest
+    "returns OOB code panel"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-delete)))
+      (assert-true (string? result))))
+  (deftest
+    "is valid SX"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-delete)))
+      (assert-true (> (len result) 0)))))
+
+(defsuite
+  "example:inline-edit"
+  (deftest
+    "edit-form returns current value"
+    (reset-mocks!)
+    (set! _mock-args {:value "hello"})
+    (let
+      ((result (run-handler handler:ex-edit-form)))
+      (assert-true (contains? result "hello"))))
+  (deftest
+    "edit-save returns new value"
+    (reset-mocks!)
+    (set! _mock-form {:value "updated"})
+    (let
+      ((result (run-handler handler:ex-edit-save)))
+      (assert-true (contains? result "updated"))))
+  (deftest
+    "edit-cancel restores original"
+    (reset-mocks!)
+    (set! _mock-args {:value "original"})
+    (let
+      ((result (run-handler handler:ex-edit-cancel)))
+      (assert-true (contains? result "original"))))
+  (deftest
+    "full cycle: edit → save → cancel"
+    (reset-mocks!)
+    (set! _mock-args {:value "v1"})
+    (let
+      ((edit (run-handler handler:ex-edit-form)))
+      (do
+        (assert-true (contains? edit "v1"))
+        (set! _mock-form {:value "v2"})
+        (let
+          ((saved (run-handler handler:ex-edit-save)))
+          (do
+            (assert-true (contains? saved "v2"))
+            (set! _mock-args {:value "v1"})
+            (let
+              ((cancelled (run-handler handler:ex-edit-cancel)))
+              (assert-true (contains? cancelled "v1")))))))))
+
+(defsuite
+  "example:oob-updates"
+  (deftest
+    "returns timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-oob)))
+      (assert-true (contains? result _mock-now))))
+  (deftest
+    "includes OOB swap target"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-oob)))
+      (assert-true (contains? result "sx-swap-oob")))))
+
+(defsuite
+  "example:lazy-load"
+  (deftest
+    "returns timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-lazy)))
+      (assert-true (contains? result _mock-now))))
+  (deftest
+    "includes content message"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-lazy)))
+      (assert-true (contains? result "page render")))))
+
+(defsuite
+  "example:infinite-scroll"
+  (deftest
+    "page 2 returns items"
+    (reset-mocks!)
+    (set! _mock-args {:page "2"})
+    (let
+      ((result (run-handler handler:ex-scroll)))
+      (assert-true (> (len result) 50))))
+  (deftest
+    "page 10 shows all loaded"
+    (reset-mocks!)
+    (set! _mock-args {:page "10"})
+    (let
+      ((result (run-handler handler:ex-scroll)))
+      (assert-true (contains? result "loaded")))))
+
+(defsuite
+  "example:progress-bar"
+  (deftest
+    "start creates job counter"
+    (reset-mocks!)
+    (run-handler handler:ex-progress-start)
+    (assert-equal 1 (get _mock-state "ex-job-counter")))
+  (deftest
+    "start initializes job at 0"
+    (reset-mocks!)
+    (run-handler handler:ex-progress-start)
+    (assert-equal 0 (get _mock-state "ex-job-1")))
+  (deftest
+    "status increments progress"
+    (reset-mocks!)
+    (set! _mock-state (assoc _mock-state "ex-job-1" 50))
+    (set! _mock-args {:job "1"})
+    (run-handler handler:ex-progress-status)
+    (assert-true (> (get _mock-state "ex-job-1") 50)))
+  (deftest
+    "full cycle: start → poll status"
+    (reset-mocks!)
+    (run-handler handler:ex-progress-start)
+    (set! _mock-args {:job "1"})
+    (run-handler handler:ex-progress-status)
+    (assert-true (> (get _mock-state "ex-job-1") 0))))
+
+(defsuite
+  "example:search"
+  (deftest
+    "finds Python"
+    (reset-mocks!)
+    (set! _mock-args {:q "python"})
+    (let
+      ((result (run-handler handler:ex-search)))
+      (assert-true (contains? result "Python"))))
+  (deftest
+    "finds multiple matches"
+    (reset-mocks!)
+    (set! _mock-args {:q "java"})
+    (let
+      ((result (run-handler handler:ex-search)))
+      (assert-true (contains? result "Java"))))
+  (deftest
+    "empty query returns prompt"
+    (reset-mocks!)
+    (set! _mock-args {:q ""})
+    (let
+      ((result (run-handler handler:ex-search)))
+      (assert-true (contains? result "type to search"))))
+  (deftest
+    "no match returns empty"
+    (reset-mocks!)
+    (set! _mock-args {:q "zzzznothing"})
+    (let
+      ((result (run-handler handler:ex-search)))
+      (assert-true (not (contains? result "Python"))))))
+
+(defsuite
+  "example:validation"
+  (deftest
+    "rejects empty"
+    (reset-mocks!)
+    (set! _mock-args {:email ""})
+    (let
+      ((result (run-handler handler:ex-validate)))
+      (assert-true (contains? result "required"))))
+  (deftest
+    "rejects no @"
+    (reset-mocks!)
+    (set! _mock-args {:email "bad"})
+    (let
+      ((result (run-handler handler:ex-validate)))
+      (assert-true (contains? result "@"))))
+  (deftest
+    "rejects taken email"
+    (reset-mocks!)
+    (set! _mock-args {:email "alice@example.com"})
+    (let
+      ((result (run-handler handler:ex-validate)))
+      (assert-true (contains? result "taken"))))
+  (deftest
+    "accepts valid email"
+    (reset-mocks!)
+    (set! _mock-args {:email "new@example.com"})
+    (let
+      ((result (run-handler handler:ex-validate)))
+      (assert-true (contains? result "available"))))
+  (deftest
+    "submit with valid email succeeds"
+    (reset-mocks!)
+    (set! _mock-form {:email "ok@test.com"})
+    (let
+      ((result (run-handler handler:ex-validate-submit)))
+      (assert-true (contains? result "ok@test.com")))))
+
+(defsuite
+  "example:dependent-select"
+  (deftest
+    "returns options for frontend"
+    (reset-mocks!)
+    (set! _mock-args {:category "frontend"})
+    (let
+      ((result (run-handler handler:ex-values)))
+      (assert-true (contains? result "option"))))
+  (deftest
+    "empty category returns empty"
+    (reset-mocks!)
+    (set! _mock-args {:category ""})
+    (let
+      ((result (run-handler handler:ex-values)))
+      (assert-true (string? result)))))
+
+(defsuite
+  "example:form-reset"
+  (deftest
+    "echoes submitted message"
+    (reset-mocks!)
+    (set! _mock-form {:message "Hello world"})
+    (let
+      ((result (run-handler handler:ex-reset-submit)))
+      (assert-true (contains? result "Hello world"))))
+  (deftest
+    "includes timestamp"
+    (reset-mocks!)
+    (set! _mock-form {:message "test"})
+    (let
+      ((result (run-handler handler:ex-reset-submit)))
+      (assert-true (contains? result _mock-now)))))
+
+(defsuite
+  "example:row-editing"
+  (deftest
+    "form loads row data"
+    (reset-mocks!)
+    (set! _mock-args {:row-id "1"})
+    (let
+      ((result (run-handler handler:ex-editrow-form)))
+      (assert-true (> (len result) 10))))
+  (deftest
+    "save stores row in state"
+    (reset-mocks!)
+    (set! _mock-args {:row-id "1"})
+    (set! _mock-form {:stock "50" :price "9.99" :name "Widget"})
+    (run-handler handler:ex-editrow-save)
+    (let
+      ((row (get _mock-state "ex-row-1")))
+      (assert-equal "Widget" (get row "name"))))
+  (deftest
+    "save stores price"
+    (reset-mocks!)
+    (set! _mock-args {:row-id "1"})
+    (set! _mock-form {:stock "5" :price "19.99" :name "X"})
+    (run-handler handler:ex-editrow-save)
+    (let
+      ((row (get _mock-state "ex-row-1")))
+      (assert-equal "19.99" (get row "price"))))
+  (deftest
+    "cancel returns view"
+    (reset-mocks!)
+    (set! _mock-args {:row-id "1"})
+    (let
+      ((result (run-handler handler:ex-editrow-cancel)))
+      (assert-true (> (len result) 10))))
+  (deftest
+    "full cycle: edit → save → cancel"
+    (reset-mocks!)
+    (set! _mock-args {:row-id "2"})
+    (let
+      ((form (run-handler handler:ex-editrow-form)))
+      (do
+        (assert-true (string? form))
+        (set! _mock-form {:stock "100" :price "5.00" :name "Gadget"})
+        (run-handler handler:ex-editrow-save)
+        (assert-equal "Gadget" (get (get _mock-state "ex-row-2") "name"))
+        (let
+          ((view (run-handler handler:ex-editrow-cancel)))
+          (assert-true (string? view)))))))
+
+(defsuite
+  "example:profile-editing"
+  (deftest
+    "edit loads current profile"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-pp-edit-all)))
+      (assert-true (string? result))))
+  (deftest
+    "put saves all fields"
+    (reset-mocks!)
+    (set! _mock-form {:email "bob@test.com" :role "admin" :name "Bob"})
+    (run-handler handler:ex-pp-put)
+    (let
+      ((p (get _mock-state "ex-profile")))
+      (do
+        (assert-equal "Bob" (get p "name"))
+        (assert-equal "bob@test.com" (get p "email"))
+        (assert-equal "admin" (get p "role")))))
+  (deftest
+    "cancel returns view"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-pp-cancel)))
+      (assert-true (string? result))))
+  (deftest
+    "full cycle: edit → put → view"
+    (reset-mocks!)
+    (run-handler handler:ex-pp-edit-all)
+    (set! _mock-form {:email "c@x.com" :role "user" :name "Carol"})
+    (run-handler handler:ex-pp-put)
+    (let
+      ((view (run-handler handler:ex-pp-cancel)))
+      (assert-true (contains? view "Carol")))))
+
+(defsuite
+  "example:bulk-operations"
+  (deftest
+    "activates selected users"
+    (reset-mocks!)
+    (set! _mock-args {:action "activate"})
+    (set! _mock-form {:ids (list "u1" "u2")})
+    (let
+      ((result (run-handler handler:ex-bulk)))
+      (assert-true (string? result)))))
+
+(defsuite
+  "example:swap-modes"
+  (deftest
+    "increments counter"
+    (reset-mocks!)
+    (set! _mock-args {:mode "beforeend"})
+    (run-handler handler:ex-swap-log)
+    (assert-equal 1 (get _mock-state "ex-swap-n")))
+  (deftest
+    "returns timestamp"
+    (reset-mocks!)
+    (set! _mock-args {:mode "innerHTML"})
+    (let
+      ((result (run-handler handler:ex-swap-log)))
+      (assert-true (contains? result _mock-now))))
+  (deftest
+    "includes OOB counter update"
+    (reset-mocks!)
+    (set! _mock-args {:mode "beforeend"})
+    (let
+      ((result (run-handler handler:ex-swap-log)))
+      (assert-true (contains? result "swap-counter")))))
+
+(defsuite
+  "example:dashboard"
+  (deftest
+    "shows user count"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-dashboard)))
+      (assert-true (contains? result "142"))))
+  (deftest
+    "shows revenue"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-dashboard)))
+      (assert-true (contains? result "4.2k"))))
+  (deftest
+    "includes timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-dashboard)))
+      (assert-true (contains? result _mock-now)))))
+
+(defsuite
+  "example:tabs"
+  (deftest
+    "returns tab content"
+    (reset-mocks!)
+    (set! _mock-args {:tab "features"})
+    (let
+      ((result (run-handler handler:ex-tabs)))
+      (assert-true (> (len result) 20))))
+  (deftest
+    "includes OOB tab buttons"
+    (reset-mocks!)
+    (set! _mock-args {:tab "features"})
+    (let
+      ((result (run-handler handler:ex-tabs)))
+      (assert-true (contains? result "tab-buttons")))))
+
+(defsuite
+  "example:animation"
+  (deftest
+    "returns content"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-animate)))
+      (assert-true (> (len result) 20))))
+  (deftest
+    "includes timestamp"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-animate)))
+      (assert-true (contains? result _mock-now)))))
+
+(defsuite
+  "example:dialog"
+  (deftest
+    "open returns modal content"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-dialog)))
+      (assert-true (> (len result) 20))))
+  (deftest
+    "close returns response"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-dialog-close)))
+      (assert-true (string? result)))))
+
+(defsuite
+  "example:keyboard"
+  (deftest
+    "returns action for Enter"
+    (reset-mocks!)
+    (set! _mock-args {:key "Enter"})
+    (let
+      ((result (run-handler handler:ex-keyboard)))
+      (assert-true (> (len result) 10))))
+  (deftest
+    "returns action for Escape"
+    (reset-mocks!)
+    (set! _mock-args {:key "Escape"})
+    (let
+      ((result (run-handler handler:ex-keyboard)))
+      (assert-true (> (len result) 10)))))
+
+(defsuite
+  "example:json-echo"
+  (deftest
+    "echoes content type"
+    (reset-mocks!)
+    (set! _mock-body "{\"key\":\"val\"}")
+    (set! _mock-content-type "application/json")
+    (let
+      ((result (run-handler handler:ex-json-echo)))
+      (assert-true (contains? result "application/json"))))
+  (deftest
+    "echoes body"
+    (reset-mocks!)
+    (set! _mock-body "{\"hello\":\"world\"}")
+    (set! _mock-content-type "application/json")
+    (let
+      ((result (run-handler handler:ex-json-echo)))
+      (assert-true (contains? result "hello")))))
+
+(defsuite
+  "example:echo-vals"
+  (deftest
+    "echoes query args"
+    (reset-mocks!)
+    (set! _mock-args {:foo "bar" :baz "qux"})
+    (let
+      ((result (run-handler handler:ex-echo-vals)))
+      (assert-true (string? result)))))
+
+(defsuite
+  "example:echo-headers"
+  (deftest
+    "echoes x-prefixed headers"
+    (reset-mocks!)
+    (set! _mock-headers {:x-custom "value" :content-type "text/plain"})
+    (let
+      ((result (run-handler handler:ex-echo-headers)))
+      (assert-true (string? result)))))
+
+(defsuite
+  "example:loading"
+  (deftest
+    "returns content (sleep mocked)"
+    (reset-mocks!)
+    (let
+      ((result (run-handler handler:ex-slow)))
+      (assert-true (contains? result _mock-now)))))
+
+(defsuite
+  "example:dedup-search"
+  (deftest
+    "returns search result"
+    (reset-mocks!)
+    (set! _mock-args {:q "test"})
+    (let
+      ((result (run-handler handler:ex-slow-search)))
+      (assert-true (contains? result "test")))))
+
+(defsuite
+  "example:retry"
+  (deftest
+    "first call increments counter"
+    (reset-mocks!)
+    (run-handler handler:ex-flaky)
+    (assert-equal 1 (get _mock-state "ex-flaky-n")))
+  (deftest
+    "third call succeeds (mod 3)"
+    (reset-mocks!)
+    (run-handler handler:ex-flaky)
+    (run-handler handler:ex-flaky)
+    (let
+      ((result (run-handler handler:ex-flaky)))
+      (do
+        (assert-equal 3 (get _mock-state "ex-flaky-n"))
+        (assert-true (contains? result "Success"))))))

web/tests/test-swap-integration.sx

@@ -0,0 +1,204 @@
+(define _mock-form (dict))
+
+(define _mock-args (dict))
+
+(define _mock-state (dict))
+
+(define _mock-body "")
+
+(define _mock-content-type "")
+
+(define _mock-headers (dict))
+
+(define _mock-now "12:00:00")
+
+(define
+  reset-mocks!
+  (fn
+    ()
+    (do
+      (set! _mock-form (dict))
+      (set! _mock-args (dict))
+      (set! _mock-state (dict))
+      (set! _mock-body "")
+      (set! _mock-content-type "")
+      (set! _mock-headers (dict)))))
+
+(define
+  helper
+  (fn
+    (name a1 a2)
+    (cond
+      (= name "request-form")
+      (let
+        ((key (or a1 "")) (default (if (nil? a2) "" a2)))
+        (let ((val (get _mock-form key))) (if (nil? val) default val)))
+      (= name "request-arg")
+      (let
+        ((key (or a1 "")) (default a2))
+        (let ((val (get _mock-args key))) (if (nil? val) default val)))
+      (= name "state-get")
+      (let
+        ((key (or a1 "")) (default a2))
+        (let ((val (get _mock-state key))) (if (nil? val) default val)))
+      (= name "state-set!")
+      (do (set! _mock-state (assoc _mock-state a1 a2)) nil)
+      (= name "now")
+      _mock-now
+      (= name "component-source")
+      (str "(defcomp " a1 " () (div))")
+      (= name "request-json")
+      _mock-body
+      (= name "request-content-type")
+      _mock-content-type
+      (= name "request-form-list")
+      (or (get _mock-form a1) (list))
+      (= name "request-args-all")
+      _mock-args
+      (= name "request-headers-all")
+      _mock-headers
+      (= name "request-form-all")
+      _mock-form
+      (= name "request-header")
+      (or (get _mock-headers a1) a2)
+      (= name "request-file-name")
+      (or (get _mock-form a1) "")
+      (= name "into")
+      (let
+        ((coll (if (nil? a2) a1 a2)))
+        (if
+          (dict? coll)
+          (map (fn (key) (list key (get coll key))) (keys coll))
+          (if (nil? coll) (list) coll)))
+      :else nil)))
+
+(define sleep (fn (ms) nil))
+
+(define set-response-status (fn (code) nil))
+
+(define json-encode (fn (val) (inspect val)))
+
+(define
+  run-handler
+  (fn
+    (hdef)
+    (let
+      ((result (aser (get hdef "body") (get hdef "closure"))))
+      (if
+        (sx-expr? result)
+        (sx-expr-source result)
+        (if (string? result) result (str result))))))
+
+(defsuite
+  "swap:click-to-load"
+  (deftest
+    "innerHTML replaces target content"
+    (reset-mocks!)
+    (let
+      ((page "(div :id \"click-result\" (p \"Click the button\"))")
+        (response (run-handler handler:ex-click)))
+      (let
+        ((result (sx-swap page "innerHTML" "click-result" response)))
+        (do
+          (assert-true (contains? result "~examples/click-result"))
+          (assert-true (contains? result "12:00:00"))
+          (assert-false (contains? result "Click the button")))))))
+
+(defsuite
+  "swap:form-submission"
+  (deftest
+    "innerHTML replaces with greeting"
+    (reset-mocks!)
+    (set! _mock-form {:name "Alice"})
+    (let
+      ((page "(div :id \"form-result\" (p \"Submit the form\"))")
+        (response (run-handler handler:ex-form)))
+      (let
+        ((result (sx-swap page "innerHTML" "form-result" response)))
+        (do
+          (assert-true (contains? result "Alice"))
+          (assert-false (contains? result "Submit the form")))))))
+
+(defsuite
+  "swap:polling"
+  (deftest
+    "innerHTML shows counter after increment"
+    (reset-mocks!)
+    (let
+      ((page "(div :id \"poll-result\" (p \"Waiting...\"))")
+        (response (run-handler handler:ex-poll)))
+      (let
+        ((result (sx-swap page "innerHTML" "poll-result" response)))
+        (do
+          (assert-true (contains? result "1"))
+          (assert-false (contains? result "Waiting")))))))
+
+(defsuite
+  "swap:oob-updates"
+  (deftest
+    "primary + OOB both update"
+    (reset-mocks!)
+    (let
+      ((page "(div (div :id \"oob-box-a\" (p \"A old\")) (div :id \"oob-box-b\" (p \"B old\")))")
+        (response (run-handler handler:ex-oob)))
+      (let
+        ((result (apply-response page response "innerHTML" "oob-box-a")))
+        (do
+          (assert-true (contains? result "Box A updated!"))
+          (assert-true (contains? result "Box B updated!"))
+          (assert-false (contains? result "A old"))
+          (assert-false (contains? result "B old")))))))
+
+(defsuite
+  "swap:search"
+  (deftest
+    "innerHTML replaces search results"
+    (reset-mocks!)
+    (set! _mock-args {:q "Python"})
+    (let
+      ((page "(div :id \"search-result\" (p \"Type to search\"))")
+        (response (run-handler handler:ex-search)))
+      (let
+        ((result (sx-swap page "innerHTML" "search-result" response)))
+        (do
+          (assert-true (contains? result "Python"))
+          (assert-false (contains? result "Type to search")))))))
+
+(defsuite
+  "swap:delete-row"
+  (deftest
+    "outerHTML removes element"
+    (let
+      ((page "(table (tr :id \"row-1\" (td \"Item 1\")) (tr :id \"row-2\" (td \"Item 2\")))")
+        (response ""))
+      (let
+        ((result (sx-swap page "outerHTML" "row-1" response)))
+        (do
+          (assert-false (contains? result "Item 1"))
+          (assert-true (contains? result "Item 2")))))))
+
+(defsuite
+  "swap:beforeend"
+  (deftest
+    "appends new item to list"
+    (let
+      ((page "(ul :id \"items\" (li \"first\"))") (response "(li \"second\")"))
+      (let
+        ((result (sx-swap page "beforeend" "items" response)))
+        (do
+          (assert-true (contains? result "first"))
+          (assert-true (contains? result "second")))))))
+
+(defsuite
+  "swap:state-across-calls"
+  (deftest
+    "counter increments across handler calls"
+    (reset-mocks!)
+    (let
+      ((r1 (run-handler handler:ex-poll)))
+      (let
+        ((r2 (run-handler handler:ex-poll)))
+        (let
+          ((page "(div :id \"counter\" (span \"0\"))")
+            (result (sx-swap page "innerHTML" "counter" r2)))
+          (assert-true (contains? result "2")))))))