feat(ack): support project agent routing overrides

skills/ack/templates/tasks.schema.json

@@ -591,8 +591,16 @@
       "minItems": 1,
       "uniqueItems": true,
       "items": {
-        "type": "string",
-        "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+        "oneOf": [
+          {
+            "type": "string",
+            "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+          },
+          {
+            "type": "null",
+            "description": "仅 Pi 使用 null 表示其配置的默认模型"
+          }
+        ]
       }
     },
     "modelTierAllowlist": {
@@ -633,6 +641,12 @@
         },
         "grok": {
           "$ref": "#/definitions/modelRoleAllowlist"
+        },
+        "omp": {
+          "$ref": "#/definitions/modelRoleAllowlist"
+        },
+        "pi": {
+          "$ref": "#/definitions/modelRoleAllowlist"
         }
       }
     },
@@ -661,7 +675,8 @@
             "codex",
             "cursor-agent",
             "grok",
-            "omp"
+            "omp",
+            "pi"
           ]
         },
         "tier": {
@@ -672,8 +687,16 @@
           ]
         },
         "model": {
-          "type": "string",
-          "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+          "oneOf": [
+            {
+              "type": "string",
+              "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+            },
+            {
+              "type": "null",
+              "description": "仅 Pi 使用 null 表示其配置的默认模型"
+            }
+          ]
         },
         "reasoningEffort": {
           "type": [
@@ -860,7 +883,8 @@
             "codex",
             "cursor-agent",
             "grok",
-            "omp"
+            "omp",
+            "pi"
           ]
         },
         "tier": {
@@ -871,8 +895,16 @@
           ]
         },
         "model": {
-          "type": "string",
-          "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+          "oneOf": [
+            {
+              "type": "string",
+              "pattern": "^[A-Za-z0-9][A-Za-z0-9._:/+@-]{0,127}$"
+            },
+            {
+              "type": "null",
+              "description": "仅 Pi 使用 null 表示其配置的默认模型"
+            }
+          ]
         },
         "reasoningEffort": {
           "type": [
@@ -1018,6 +1050,13 @@
         "boardHash": {
           "$ref": "#/definitions/sha256"
         },
+        "routingSource": {
+          "type": "string",
+          "minLength": 1
+        },
+        "routingHash": {
+          "$ref": "#/definitions/sha256"
+        },
         "slot": {
           "type": "integer",
           "minimum": 1,