Declare Phase 7c+7d page helpers in boundary.sx and register orchestration tests in app runner

Adds optimistic-demo-data, action:add-demo-item, offline-demo-data
to boundary spec. Adds orchestration test spec to in-app test runner
with mocked platform functions.

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

sx/sx/boundary.sx

@@ -79,3 +79,18 @@
   :params ()
   :returns "dict"
   :service "sx")
+
+(define-page-helper "optimistic-demo-data"
+  :params ()
+  :returns "dict"
+  :service "sx")
+
+(define-page-helper "action:add-demo-item"
+  :params (label)
+  :returns "dict"
+  :service "sx")
+
+(define-page-helper "offline-demo-data"
+  :params ()
+  :returns "dict"
+  :service "sx")

sx/sxc/pages/helpers.py

@@ -715,6 +715,7 @@ def _run_modular_tests(spec_name: str) -> dict:
         "render": {"file": "test-render.sx", "needs": ["render-html"]},
         "deps": {"file": "test-deps.sx", "needs": []},
         "engine": {"file": "test-engine.sx", "needs": []},
+        "orchestration": {"file": "test-orchestration.sx", "needs": []},
     }
 
     specs_to_run = list(SPECS.keys()) if spec_name == "all" else [spec_name]
@@ -788,6 +789,50 @@ def _run_modular_tests(spec_name: str) -> dict:
                 env["filter-params"] = filter_params
             except ImportError:
                 eval_file("engine.sx")
+        elif sn == "orchestration":
+            # Mock platform functions for orchestration tests
+            _mock_ts = [1000]
+            env["now-ms"] = lambda: _mock_ts[0]
+            env["log-info"] = lambda *_a: NIL
+            env["log-warn"] = lambda *_a: NIL
+            env["execute-action"] = lambda act, pay, ok_cb, _err: (ok_cb(pay), NIL)[-1]
+            env["try-rerender-page"] = lambda *_a: NIL
+            env["persist-offline-data"] = lambda *_a: NIL
+            env["retrieve-offline-data"] = lambda: NIL
+            env["dict-delete!"] = lambda d, k: (d.pop(k, None), NIL)[-1] if isinstance(d, dict) else NIL
+            # DOM/browser stubs (never called by tests)
+            _noop = lambda *_a: NIL
+            for stub in [
+                "try-parse-json", "dom-dispatch", "dom-query-selector",
+                "dom-get-attribute", "dom-set-attribute", "dom-set-text-content",
+                "dom-append", "dom-insert-html-adjacent", "dom-remove",
+                "dom-outer-html", "dom-inner-html", "dom-create-element",
+                "dom-set-inner-html", "dom-morph", "dom-get-tag",
+                "dom-query-selector-all", "dom-add-event-listener",
+                "dom-set-timeout", "dom-prevent-default", "dom-closest",
+                "dom-matches", "dom-get-id", "dom-set-id", "dom-form-data",
+                "dom-is-form", "browser-location-href", "browser-push-state",
+                "browser-replace-state", "sx-hydrate-elements", "render-to-dom",
+                "hoist-head-elements-full", "url-pathname",
+            ]:
+                if stub not in env:
+                    env[stub] = _noop
+            # Load engine (orchestration depends on it)
+            try:
+                from shared.sx.ref.sx_ref import (
+                    parse_time, parse_trigger_spec, default_trigger,
+                    parse_swap_spec, parse_retry_spec, filter_params,
+                )
+                env["parse-time"] = parse_time
+                env["parse-trigger-spec"] = parse_trigger_spec
+                env["default-trigger"] = default_trigger
+                env["parse-swap-spec"] = parse_swap_spec
+                env["parse-retry-spec"] = parse_retry_spec
+                env["next-retry-ms"] = lambda cur, cap: min(cur * 2, cap)
+                env["filter-params"] = filter_params
+            except ImportError:
+                eval_file("engine.sx")
+            eval_file("orchestration.sx")
 
         eval_file(spec["file"])