Improve consistency of sync_compatible when running flows in remote environments

src/prefect/utilities/asyncutils.py

@@ -267,11 +267,17 @@ async def run_sync_in_worker_thread(
     Note that cancellation of threads will not result in interrupted computation, the
     thread may continue running — the outcome will just be ignored.
     """
-    call = partial(__fn, *args, **kwargs)
-    result = await anyio.to_thread.run_sync(
-        call_with_mark, call, abandon_on_cancel=True, limiter=get_thread_limiter()
-    )
-    return result
+    # When running a sync function in a worker thread, we set this flag so that
+    # any root sync compatible functions will run as sync functions
+    token = RUNNING_ASYNC_FLAG.set(False)
+    try:
+        call = partial(__fn, *args, **kwargs)
+        result = await anyio.to_thread.run_sync(
+            call_with_mark, call, abandon_on_cancel=True, limiter=get_thread_limiter()
+        )
+        return result
+    finally:
+        RUNNING_ASYNC_FLAG.reset(token)
 
 
 def call_with_mark(call):

tests/deployment/test_base.py

@@ -150,7 +150,7 @@ async def test_initialize_project_with_docker_recipe_default_image(self, recipe)
 class TestDiscoverFlows:
     async def test_find_all_flows_in_dir_tree(self, project_dir):
         flows = await _search_for_flow_functions(str(project_dir))
-        assert len(flows) == 6, f"Expected 6 flows, found {len(flows)}"
+        assert len(flows) == 7, f"Expected 7 flows, found {len(flows)}"
 
         expected_flows = [
             {
@@ -191,6 +191,11 @@ async def test_find_all_flows_in_dir_tree(self, project_dir):
                     project_dir / "import-project" / "my_module" / "flow.py"
                 ),
             },
+            {
+                "flow_name": "uses_block",
+                "function_name": "uses_block",
+                "filepath": str(project_dir / "flows" / "uses_block.py"),
+            },
         ]
 
         for flow in flows:

tests/test-projects/flows/uses_block.py

@@ -0,0 +1,14 @@
+import uuid
+
+from prefect import flow
+from prefect.blocks.system import Secret
+
+block_name = f"foo-{uuid.uuid4()}"
+Secret(value="bar").save("foo")
+
+my_secret = Secret.load("foo")
+
+
+@flow
+async def uses_block():
+    return my_secret.get()

tests/test_flow_engine.py

@@ -11,7 +11,7 @@
 import pydantic
 import pytest
 
-from prefect import Flow, flow, task
+from prefect import Flow, __development_base_path__, flow, task
 from prefect._internal.compatibility.experimental import ExperimentalFeature
 from prefect.client.orchestration import PrefectClient, SyncPrefectClient
 from prefect.client.schemas.filters import FlowFilter, FlowRunFilter
@@ -37,6 +37,7 @@
 from prefect.logging import get_run_logger
 from prefect.server.schemas.core import FlowRun as ServerFlowRun
 from prefect.utilities.callables import get_call_parameters
+from prefect.utilities.filesystem import tmpchdir
 
 
 @flow
@@ -1730,3 +1731,34 @@ def g(required: str, model: TheModel = {"x": [1, 2, 3]}):  # type: ignore
                 yield i
 
         assert [i for i in g("hello")] == ["hello", 1, 2, 3]
+
+
+class TestLoadFlowAndFlowRun:
+    async def test_load_flow_from_script_with_module_level_sync_compatible_call(
+        self, prefect_client: PrefectClient, tmp_path
+    ):
+        """
+        This test ensures that when a worker or runner loads a flow from a script, and
+        that script contains a module-level call to a sync-compatible function, the sync
+        compatible function is correctly runs as sync and does not prevent the flow from
+        being loaded.
+
+        Regression test for https://github.com/PrefectHQ/prefect/issues/14625
+        """
+        flow_id = await prefect_client.create_flow_from_name(flow_name="uses_block")
+        deployment_id = await prefect_client.create_deployment(
+            flow_id=flow_id,
+            name="test-load-flow-from-script-with-module-level-sync-compatible-call",
+            path=str(__development_base_path__ / "tests" / "test-projects" / "flows"),
+            entrypoint="uses_block.py:uses_block",
+        )
+        api_flow_run = await prefect_client.create_flow_run_from_deployment(
+            deployment_id=deployment_id
+        )
+
+        with tmpchdir(tmp_path):
+            flow_run, flow = load_flow_and_flow_run(api_flow_run.id)
+
+        assert flow_run.id == api_flow_run.id
+
+        assert await flow() == "bar"