perf(react): stabilize useFlow/useStepFlow action references

.changeset/stable-useflow-actions.md

@@ -0,0 +1,7 @@
+---
+"@stackflow/react": patch
+---
+
+Memoize the action functions returned by `useFlow` and `useStepFlow` so their references stay stable across renders.
+
+Previously these hooks rebuilt their action object (`push`/`replace`/`pop`, `pushStep`/`replaceStep`/`popStep`) on every render, giving the returned functions a new reference each time. Since the underlying core actions are already a stable reference, the returned actions are now memoized on them (the same approach `usePrepare` already uses). This keeps the functions referentially stable when placed in `useEffect`/`useCallback` dependency arrays, avoiding unnecessary re-runs.

integrations/react/src/useFlow.ts

@@ -1,5 +1,6 @@
-import { useCoreActions } from "./core";
+import { useMemo } from "react";
 import type { Actions } from "./Actions";
+import { useCoreActions } from "./core";
 import { makeActions } from "./makeActions";
 
 export type FlowOutput = {
@@ -9,5 +10,5 @@ export type FlowOutput = {
 export function useFlow(): Actions {
   const coreActions = useCoreActions();
 
-  return makeActions(() => coreActions);
+  return useMemo(() => makeActions(() => coreActions), [coreActions]);
 }

integrations/react/src/useStepFlow.ts

@@ -2,6 +2,7 @@ import type {
   InferActivityParams,
   RegisteredActivityName,
 } from "@stackflow/config";
+import { useMemo } from "react";
 import { useCoreActions } from "./core";
 import { makeStepActions } from "./makeStepActions";
 import type { StepActions } from "./StepActions";
@@ -11,5 +12,5 @@ export function useStepFlow<ActivityName extends RegisteredActivityName>(
 ): StepActions<InferActivityParams<ActivityName>> {
   const coreActions = useCoreActions();
 
-  return makeStepActions(() => coreActions);
+  return useMemo(() => makeStepActions(() => coreActions), [coreActions]);
 }