Plugins: add bound TaskFlow runtime (#59622)

Merged via squash.

Prepared head SHA: b4649f3238
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Reviewed-by: @mbelinky

src/plugins/runtime/index.test.ts

@@ -189,6 +189,15 @@ describe("plugin runtime command execution", () => {
         ]);
       },
     },
+    {
+      name: "exposes runtime.taskFlow binding helpers",
+      assert: (runtime: ReturnType<typeof createPluginRuntime>) => {
+        expectFunctionKeys(runtime.taskFlow as Record<string, unknown>, [
+          "bindSession",
+          "fromToolContext",
+        ]);
+      },
+    },
     {
       name: "exposes runtime.agent host helpers",
       assert: (runtime: ReturnType<typeof createPluginRuntime>) => {