diff --git a/packages/kbn-optimizer/limits.yml b/packages/kbn-optimizer/limits.yml
index 106f59419bf7e..12f408096dd8a 100644
--- a/packages/kbn-optimizer/limits.yml
+++ b/packages/kbn-optimizer/limits.yml
@@ -6,7 +6,7 @@ pageLoadAssetSize:
   aiAssistantManagementSelection: 13590
   aiops: 15227
   alerting: 22371
-  alertingVTwo: 361715
+  alertingVTwo: 362170
   apm: 38573
   apmSourcesAccess: 2278
   automaticImport: 12162
diff --git a/src/core/server/integration_tests/ci_checks/saved_objects/check_registered_types.test.ts b/src/core/server/integration_tests/ci_checks/saved_objects/check_registered_types.test.ts
index bbf2619e54bd0..c56b8d6c3a46d 100644
--- a/src/core/server/integration_tests/ci_checks/saved_objects/check_registered_types.test.ts
+++ b/src/core/server/integration_tests/ci_checks/saved_objects/check_registered_types.test.ts
@@ -62,7 +62,7 @@ describe('checking migration metadata changes on all registered SO types', () =>
         "ad_hoc_run_params": "9c372f2a8f8b468e9b699a6df633c7f14fab7f13216c9ec160813e75bae56098",
         "alert": "119624b6025ea6794d2c33e2b41c2e4730d10446430b285691f7638ee6787af5",
         "alerting_notification_policy": "81fc65ed6652cd1196f83b4222f227e8c7a3f646a6e044f63a2d82f12dacbfb0",
-        "alerting_rule": "9e26ddcbca3edb3803dcfe3d6bf908341441fb32c67005cab71ae0f7b9841387",
+        "alerting_rule": "8f80d561d2b3caf07925be4a5fff52d8433ca3f3f204723f6f3e9e32dbce7f42",
         "alerting_rule_template": "a26521005d8a51af336ec95a2097c4bd073980c050e3c675cec3851acff78fd9",
         "api_key_pending_invalidation": "b5a0fe007bff147bbb0ef7d0393c976f777ccb470359090d79890a769baf3c68",
         "api_key_to_invalidate": "5add5ee737ccc61cc16bbf68423d634d1354971f20926b5ff465a2a853d1723a",
@@ -303,7 +303,7 @@ describe('checking migration metadata changes on all registered SO types', () =>
         "alerting_rule|global: e78adb1490c02adb4c705491c87e08332c0f668e",
         "alerting_rule|mappings: 05a17ab7488d3b86ec25c724f21a19cd7ebb9778",
         "alerting_rule|schemas: da39a3ee5e6b4b0d3255bfef95601890afd80709",
-        "alerting_rule|10.1.0: 8b54e0f9a45fff3fbb39dd35dde15784674293f7dfb199bc10218f3658266207",
+        "alerting_rule|10.1.0: 7e2e621ff8a85dd04d0b8e374a9a8b85ce23ba968dfbacef9dfd23a003dc4afb",
         "======================================================================================",
         "alerting_rule_template|global: a8ee387a4bc794ff6450017a92742b39b79e0446",
         "alerting_rule_template|mappings: eccf889027b5ea2d292c1bf0f9280348deaec0ef",
diff --git a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.test.ts b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.test.ts
index de164de037e2a..6ee4aa81646f6 100644
--- a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.test.ts
+++ b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.test.ts
@@ -11,6 +11,11 @@ const validCreateData = {
   kind: 'alert',
   metadata: { name: 'test rule' },
   schedule: { every: '5m' },
+  evaluation: { query: { base: 'FROM logs-* | LIMIT 1' } },
+};
+
+const validCreateDataWithCondition = {
+  ...validCreateData,
   evaluation: { query: { base: 'FROM logs-* | LIMIT 1', condition: 'count > 0' } },
 };
 
@@ -19,6 +24,18 @@ describe('createRuleDataSchema', () => {
     it('accepts a minimal valid payload and applies defaults', () => {
       const result = createRuleDataSchema.parse(validCreateData);
 
+      expect(result).toEqual({
+        kind: 'alert',
+        metadata: { name: 'test rule' },
+        time_field: '@timestamp',
+        schedule: { every: '5m' },
+        evaluation: { query: { base: 'FROM logs-* | LIMIT 1' } },
+      });
+    });
+
+    it('accepts a minimal valid payload with condition', () => {
+      const result = createRuleDataSchema.parse(validCreateDataWithCondition);
+
       expect(result).toEqual({
         kind: 'alert',
         metadata: { name: 'test rule' },
@@ -30,7 +47,7 @@ describe('createRuleDataSchema', () => {
 
     it('accepts a full payload with all optional fields', () => {
       const result = createRuleDataSchema.parse({
-        ...validCreateData,
+        ...validCreateDataWithCondition,
         metadata: { name: 'test rule', owner: 'team-a', labels: ['label-1', 'label-2'] },
         time_field: 'event.created',
         schedule: { every: '5m', lookback: '10m' },
@@ -153,7 +170,7 @@ describe('createRuleDataSchema', () => {
     it('rejects an empty query', () => {
       const result = createRuleDataSchema.safeParse({
         ...validCreateData,
-        evaluation: { query: { base: '', condition: 'count > 0' } },
+        evaluation: { query: { base: '' } },
       });
       expect(result.success).toBe(false);
     });
@@ -161,7 +178,63 @@ describe('createRuleDataSchema', () => {
     it('rejects an invalid ES|QL query', () => {
       const result = createRuleDataSchema.safeParse({
         ...validCreateData,
-        evaluation: { query: { base: 'FROM |', condition: 'count > 0' } },
+        evaluation: { query: { base: 'FROM |' } },
+      });
+      expect(result.success).toBe(false);
+    });
+  });
+
+  describe('evaluation.query.condition', () => {
+    it('accepts an alert rule without condition', () => {
+      const result = createRuleDataSchema.safeParse(validCreateData);
+      expect(result.success).toBe(true);
+      expect(result.data?.evaluation.query.condition).toBeUndefined();
+    });
+
+    it('accepts an alert rule with condition', () => {
+      const result = createRuleDataSchema.safeParse(validCreateDataWithCondition);
+      expect(result.success).toBe(true);
+      expect(result.data?.evaluation.query.condition).toBe('count > 0');
+    });
+
+    it('accepts a signal rule without condition', () => {
+      const result = createRuleDataSchema.safeParse({
+        ...validCreateData,
+        kind: 'signal',
+      });
+      expect(result.success).toBe(true);
+    });
+
+    it('rejects a signal rule with condition', () => {
+      const result = createRuleDataSchema.safeParse({
+        ...validCreateDataWithCondition,
+        kind: 'signal',
+      });
+      expect(result.success).toBe(false);
+      expect(result.error?.issues[0].path).toEqual(['evaluation', 'query', 'condition']);
+    });
+
+    it('requires condition when no_data is configured', () => {
+      const result = createRuleDataSchema.safeParse({
+        ...validCreateData,
+        no_data: { behavior: 'no_data', timeframe: '10m' },
+      });
+      expect(result.success).toBe(false);
+      expect(result.error?.issues[0].path).toEqual(['evaluation', 'query', 'condition']);
+    });
+
+    it('accepts no_data with condition present', () => {
+      const result = createRuleDataSchema.safeParse({
+        ...validCreateDataWithCondition,
+        no_data: { behavior: 'no_data', timeframe: '10m' },
+      });
+      expect(result.success).toBe(true);
+    });
+
+    it('rejects an empty condition string', () => {
+      const result = createRuleDataSchema.safeParse({
+        ...validCreateData,
+        evaluation: { query: { base: 'FROM logs-* | LIMIT 1', condition: '' } },
       });
       expect(result.success).toBe(false);
     });
diff --git a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.ts b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.ts
index 2e2dadaf792bb..cf7a6332eb8c2 100644
--- a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.ts
+++ b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_data_schema.ts
@@ -62,7 +62,12 @@ const scheduleSchema = z
 const evaluationQuerySchema = z
   .object({
     base: esqlQuerySchema.describe('Base ES|QL query.'),
-    condition: z.string().min(1).max(5000).describe('Trigger condition (WHERE clause).'),
+    condition: z
+      .string()
+      .min(1)
+      .max(5000)
+      .optional()
+      .describe('Trigger condition (WHERE clause). Required when no_data is configured.'),
   })
   .strict();
 
@@ -180,18 +185,17 @@ export const createRuleDataSchema = z
     notification_policies: z.array(notificationPolicyRefSchema).optional(),
   })
   .strip()
-  /**
-   *
-   * The `.refine` method adds a custom validation to the schema.
-   * In this case, it enforces that the `state_transition` property is only allowed when `kind` is "alert".
-   * The predicate `data.kind === 'alert' || data.state_transition == null` means:
-   * - If the rule kind is "alert", `state_transition` may be present (or absent).
-   * - For any other `kind`, `state_transition` must be `null` or `undefined`.
-   * If validation fails, the specified error message will be associated with the `state_transition` field.
-   */
   .refine((data) => data.kind === 'alert' || data.state_transition == null, {
     message: 'state_transition is only allowed when kind is "alert".',
     path: ['state_transition'],
+  })
+  .refine((data) => data.kind === 'alert' || data.evaluation.query.condition == null, {
+    message: 'evaluation.query.condition is only allowed when kind is "alert".',
+    path: ['evaluation', 'query', 'condition'],
+  })
+  .refine((data) => !data.no_data || data.evaluation.query.condition != null, {
+    message: 'evaluation.query.condition is required when no_data is configured.',
+    path: ['evaluation', 'query', 'condition'],
   });
 
 export type CreateRuleData = z.infer<typeof createRuleDataSchema>;
diff --git a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_response.ts b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_response.ts
index 2a7378d47f2d0..40d506b1e31e5 100644
--- a/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_response.ts
+++ b/x-pack/platform/packages/shared/response-ops/alerting-v2-schemas/src/rule_response.ts
@@ -29,7 +29,7 @@ export interface RuleResponse {
   evaluation: {
     query: {
       base: string;
-      condition: string;
+      condition?: string;
     };
   };
   recovery_policy?: {
diff --git a/x-pack/platform/packages/shared/response-ops/yaml-rule-editor/src/types.ts b/x-pack/platform/packages/shared/response-ops/yaml-rule-editor/src/types.ts
index caeb3c01c6451..a733973c1798a 100644
--- a/x-pack/platform/packages/shared/response-ops/yaml-rule-editor/src/types.ts
+++ b/x-pack/platform/packages/shared/response-ops/yaml-rule-editor/src/types.ts
@@ -59,9 +59,12 @@ export interface CompletionContext {
 }
 
 /**
- * Default property names that should be treated as ES|QL queries
+ * YAML property names whose values contain ES|QL queries.
+ * The editor enables ES|QL syntax highlighting and auto-completion for these fields.
+ *
+ * TODO: with zod4 upgrade we can add a metadata tag to the schema to mark these fields as ES|QL queries.
  */
-export const DEFAULT_ESQL_PROPERTY_NAMES = ['query'];
+export const DEFAULT_ESQL_PROPERTY_NAMES = ['base'];
 
 /**
  * Props for the YamlRuleEditor component
diff --git a/x-pack/platform/plugins/shared/alerting_v2/public/components/create_rule_page.tsx b/x-pack/platform/plugins/shared/alerting_v2/public/components/create_rule_page.tsx
index ad44422fbc199..a9961f428905a 100644
--- a/x-pack/platform/plugins/shared/alerting_v2/public/components/create_rule_page.tsx
+++ b/x-pack/platform/plugins/shared/alerting_v2/public/components/create_rule_page.tsx
@@ -139,8 +139,9 @@ export const CreateRulePage = () => {
           evaluation: {
             query: {
               base: rule.evaluation?.query?.base ?? DEFAULT_RULE_VALUES.evaluation.query.base,
-              condition:
-                rule.evaluation?.query?.condition ?? DEFAULT_RULE_VALUES.evaluation.query.condition,
+              ...(rule.evaluation?.query?.condition != null
+                ? { condition: rule.evaluation.query.condition }
+                : {}),
             },
           },
           recovery_policy: rule.recovery_policy,
diff --git a/x-pack/platform/plugins/shared/alerting_v2/server/saved_objects/schemas/rule_saved_object_attributes/v1.ts b/x-pack/platform/plugins/shared/alerting_v2/server/saved_objects/schemas/rule_saved_object_attributes/v1.ts
index 600ef5f6e80f9..4c669eae47fb0 100644
--- a/x-pack/platform/plugins/shared/alerting_v2/server/saved_objects/schemas/rule_saved_object_attributes/v1.ts
+++ b/x-pack/platform/plugins/shared/alerting_v2/server/saved_objects/schemas/rule_saved_object_attributes/v1.ts
@@ -32,7 +32,7 @@ export const ruleSavedObjectAttributesSchema = schema.object({
   evaluation: schema.object({
     query: schema.object({
       base: schema.string(),
-      condition: schema.string(),
+      condition: schema.maybe(schema.string()),
     }),
   }),
   recovery_policy: schema.maybe(