diff --git a/src/backend/x11/backend.c b/src/backend/x11/backend.c
index b1713c5..1e385a7 100644
--- a/src/backend/x11/backend.c
+++ b/src/backend/x11/backend.c
@@ -337,3 +337,9 @@ void backend_detect_destroy(backend_detect_t *detect) {
   p_delete(&detect->outputs);
   free(detect);
 }
+
+bool backend_apply_effect(backend_t *backend, const effect_t *effects,
+                          size_t effect_count) {
+  /* TODO: */
+  return true;
+}
diff --git a/src/core/backend.h b/src/core/backend.h
index cfdec89..b3722ec 100644
--- a/src/core/backend.h
+++ b/src/core/backend.h
@@ -3,6 +3,7 @@
 #include <stddef.h>
 
 #include "core/event.h"
+#include "core/plan.h"
 #include "core/types.h"
 
 typedef struct backend_t backend_t;
@@ -31,3 +32,5 @@ void backend_detect_destroy(backend_detect_t *detect);
  * 无需 cleanup 的状态，调用方可以直接退出循环。
  */
 bool backend_next_event(backend_t *backend, event_t *event);
+bool backend_apply_effect(backend_t *backend, const effect_t *effects,
+                          size_t effect_count);
diff --git a/src/core/plan.c b/src/core/plan.c
new file mode 100644
index 0000000..d3a3c05
--- /dev/null
+++ b/src/core/plan.c
@@ -0,0 +1,22 @@
+#include "core/plan.h"
+
+#include "base/array.h"
+#include "base/memory.h"
+
+void plan_reset(plan_t *plan) {
+  if (!plan->effects || !plan->capacity) return;
+
+  p_clear(plan->effects, plan->capacity);
+  plan->count = 0;
+}
+
+void plan_cleanup(plan_t *plan) {
+  p_delete(&plan->effects);
+  plan->count = 0;
+  plan->capacity = 0;
+}
+
+void plan_push_effect(plan_t *plan, const effect_t *effect) {
+  effect_t *eft = array_push(plan->effects, plan->count, plan->capacity);
+  *eft = *effect;
+}
diff --git a/src/core/plan.h b/src/core/plan.h
new file mode 100644
index 0000000..d74a849
--- /dev/null
+++ b/src/core/plan.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "core/types.h"
+
+typedef uint32_t dirty_mask_t;
+
+typedef enum dirty_flags_t : dirty_mask_t {
+  ZDWM_DIRTY_NONE = 0,
+  ZDWM_DIRTY_LAYOUT = 1u << 0,
+} dirty_flags_t;
+
+typedef enum effect_type_t {
+  ZDWM_EFFECT_NONE,
+  ZDWM_EFFECT_MAP_WINDOW,
+  ZDWM_EFFECT_UNMAP_WINDOW,
+  ZDWM_EFFECT_FOCUS_WINDOW,
+} effect_type_t;
+
+typedef struct effect_only_window_id_t {
+  window_id_t window;
+} effect_only_window_id_t;
+
+typedef struct effect_t {
+  effect_type_t type;
+  union {
+    effect_only_window_id_t map;
+    effect_only_window_id_t unmap;
+    effect_only_window_id_t focus;
+  } as;
+} effect_t;
+
+typedef struct plan_t {
+  effect_t *effects;
+  size_t count;
+  size_t capacity;
+  dirty_mask_t dirty_flags;
+} plan_t;
+
+void plan_reset(plan_t *plan);
+void plan_cleanup(plan_t *plan);
+void plan_push_effect(plan_t *plan, const effect_t *effect);
diff --git a/src/core/policy.c b/src/core/policy.c
index 5c43169..dcb6a1a 100644
--- a/src/core/policy.c
+++ b/src/core/policy.c
@@ -102,3 +102,10 @@ bool policy_route_event(const policy_context_t *ctx, command_buffer_t *out) {
       return false;
   }
 }
+
+bool policy_apply_command(const policy_context_t *ctx,
+                          const command_buffer_t *command_buffer,
+                          plan_t *plan) {
+  /* TODO: */
+  return true;
+}
diff --git a/src/core/policy.h b/src/core/policy.h
index 14f0f0d..c0b558f 100644
--- a/src/core/policy.h
+++ b/src/core/policy.h
@@ -2,6 +2,7 @@
 
 #include "core/command_buffer.h"
 #include "core/event.h"
+#include "core/plan.h"
 #include "core/rules.h"
 #include "core/state.h"
 
@@ -12,3 +13,5 @@ typedef struct policy_context_t {
 } policy_context_t;
 
 bool policy_route_event(const policy_context_t *ctx, command_buffer_t *out);
+bool policy_apply_command(const policy_context_t *ctx,
+                          const command_buffer_t *command_buffer, plan_t *plan);
diff --git a/src/core/runtime.c b/src/core/runtime.c
index 51f6ef9..497d5ff 100644
--- a/src/core/runtime.c
+++ b/src/core/runtime.c
@@ -4,8 +4,11 @@
 
 #include "base/memory.h"
 #include "core/backend.h"
+#include "core/command_buffer.h"
 #include "core/event.h"
 #include "core/layout.h"
+#include "core/plan.h"
+#include "core/policy.h"
 #include "core/rules.h"
 #include "core/state.h"
 #include "core/wm_desc.h"
@@ -82,6 +85,8 @@ void runtime_init_desc_cleanup(runtime_init_desc_t *desc) {
 
 void runtime_shutdown(runtime_t *runtime) {
   runtime->running = false;
+  plan_cleanup(&runtime->plan);
+  command_buffer_cleanup(&runtime->command_buffer);
   layout_registry_cleanup(&runtime->layouts);
   rules_cleanup(&runtime->rules);
   state_cleanup(&runtime->state);
@@ -92,11 +97,28 @@ void runtime_shutdown(runtime_t *runtime) {
 }
 
 void runtime_run(runtime_t *runtime) {
-  for (;;) {
+  runtime->running = true;
+
+  backend_t *backend = runtime->backend;
+  command_buffer_t *command_buffer = &runtime->command_buffer;
+  plan_t *plan = &runtime->plan;
+
+  while (runtime->running) {
     event_t event = {0};
-    if (!backend_next_event(runtime->backend, &event)) {
-      break;
-    }
+    if (!backend_next_event(backend, &event)) break;
+
+    command_buffer_reset(command_buffer);
+    plan_reset(plan);
+
+    policy_context_t ctx = {
+      .state = &runtime->state,
+      .rules = &runtime->rules,
+      .event = &event,
+    };
+
+    policy_route_event(&ctx, command_buffer);
+    policy_apply_command(&ctx, command_buffer, plan);
+    if (plan->count) backend_apply_effect(backend, plan->effects, plan->count);
 
     event_cleanup(&event);
   }
diff --git a/src/core/runtime.h b/src/core/runtime.h
index d46ae2a..b3cb140 100644
--- a/src/core/runtime.h
+++ b/src/core/runtime.h
@@ -5,6 +5,7 @@
 #include "core/backend.h"
 #include "core/command_buffer.h"
 #include "core/layout.h"
+#include "core/plan.h"
 #include "core/rules.h"
 #include "core/state.h"
 
@@ -24,6 +25,7 @@ typedef struct runtime_t {
   bool running;
   bool will_restart;
 
+  plan_t plan;
   command_buffer_t command_buffer;
   state_t state;
   layout_registry_t layouts;
diff --git a/tests/config/CMakeLists.txt b/tests/config/CMakeLists.txt
index f58afde..22059c7 100644
--- a/tests/config/CMakeLists.txt
+++ b/tests/config/CMakeLists.txt
@@ -41,9 +41,12 @@ add_executable(${RUNTIME_CONFIG_TEST_APP_NAME}
     ${SOURCE_DIR}/config/defaults.c
     ${SOURCE_DIR}/config/loader.c
     ${SOURCE_DIR}/config/runtime_config.c
+    ${SOURCE_DIR}/core/command_buffer.c
     ${SOURCE_DIR}/core/event.c
     ${SOURCE_DIR}/core/layer.c
     ${SOURCE_DIR}/core/layout.c
+    ${SOURCE_DIR}/core/plan.c
+    ${SOURCE_DIR}/core/policy.c
     ${SOURCE_DIR}/core/rules.c
     ${SOURCE_DIR}/core/runtime.c
     ${SOURCE_DIR}/core/state.c
diff --git a/tests/config/runtime_config_test.c b/tests/config/runtime_config_test.c
index bfc847d..449edc2 100644
--- a/tests/config/runtime_config_test.c
+++ b/tests/config/runtime_config_test.c
@@ -22,6 +22,11 @@ bool backend_next_event(backend_t *backend, event_t *event) {
   return false;
 }
 
+bool backend_apply_effect(backend_t *backend, const effect_t *effects,
+                          size_t effect_count) {
+  return false;
+}
+
 static backend_t *test_backend_create(void) {
   return calloc(1, sizeof(backend_t));
 }
diff --git a/tests/core/CMakeLists.txt b/tests/core/CMakeLists.txt
index bcc4cd6..6d952f6 100644
--- a/tests/core/CMakeLists.txt
+++ b/tests/core/CMakeLists.txt
@@ -10,9 +10,12 @@ add_executable(${TEST_APP_NAME}
     ${SOURCE_DIR}/backend/x11/backend.c
     ${SOURCE_DIR}/backend/x11/event.c
     ${SOURCE_DIR}/backend/x11/window.c
+    ${SOURCE_DIR}/core/command_buffer.c
     ${SOURCE_DIR}/core/event.c
     ${SOURCE_DIR}/core/layer.c
     ${SOURCE_DIR}/core/layout.c
+    ${SOURCE_DIR}/core/plan.c
+    ${SOURCE_DIR}/core/policy.c
     ${SOURCE_DIR}/core/rules.c
     ${SOURCE_DIR}/core/runtime.c
     ${SOURCE_DIR}/core/state.c