Pr 2982 ci branch (#3046)

* Add json_schema alias for GrammarType

* Add tests for all aliases

* fix: various linter adjustments

* fix: end-of-file-fixer lint

* fix: add test snapshots and avoid docs change

* fix: another end-of-file-fixer lint

* feat: support json_schema grammar constraining and add tests

* fix: bump openapi doc with new grammar option

* fix: adjust test payload

* fix: bump test snaps

---------

Co-authored-by: Alex Weston <[email protected]>

Author: drbh

docs/openapi.json

@@ -1771,6 +1771,24 @@
                 "type": "string"
               }
             }
+          },
+          {
+            "type": "object",
+            "required": [
+              "type",
+              "value"
+            ],
+            "properties": {
+              "type": {
+                "type": "string",
+                "enum": [
+                  "json_schema"
+                ]
+              },
+              "value": {
+                "$ref": "#/components/schemas/JsonSchemaConfig"
+              }
+            }
           }
         ],
         "discriminator": {
@@ -1864,6 +1882,22 @@
           }
         }
       },
+      "JsonSchemaConfig": {
+        "type": "object",
+        "required": [
+          "schema"
+        ],
+        "properties": {
+          "name": {
+            "type": "string",
+            "description": "Optional name identifier for the schema",
+            "nullable": true
+          },
+          "schema": {
+            "description": "The actual JSON schema definition"
+          }
+        }
+      },
       "Message": {
         "allOf": [
           {

integration-tests/models/__snapshots__/test_grammar_response_format_llama/test_grammar_response_format_llama_json.1.json

@@ -0,0 +1,23 @@
+{
+  "choices": [
+    {
+      "finish_reason": "stop",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "{ \"unit\": \"fahrenheit\", \"temperature\": [ 72, 79, 88 ] }",
+        "role": "assistant"
+      }
+    }
+  ],
+  "created": 1740095072,
+  "id": "",
+  "model": "TinyLlama/TinyLlama-1.1B-Chat-v1.0",
+  "object": "chat.completion",
+  "system_fingerprint": "3.1.1-dev0-native",
+  "usage": {
+    "completion_tokens": 29,
+    "prompt_tokens": 135,
+    "total_tokens": 164
+  }
+}

integration-tests/models/__snapshots__/test_grammar_response_format_llama/test_grammar_response_format_llama_json.2.json

@@ -0,0 +1,23 @@
+{
+  "choices": [
+    {
+      "finish_reason": "stop",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "{ \"unit\": \"fahrenheit\", \"temperature\": [ 72, 79, 88 ] }",
+        "role": "assistant"
+      }
+    }
+  ],
+  "created": 1740095073,
+  "id": "",
+  "model": "TinyLlama/TinyLlama-1.1B-Chat-v1.0",
+  "object": "chat.completion",
+  "system_fingerprint": "3.1.1-dev0-native",
+  "usage": {
+    "completion_tokens": 29,
+    "prompt_tokens": 135,
+    "total_tokens": 164
+  }
+}

integration-tests/models/__snapshots__/test_json_schema_constrain/test_json_schema_basic.json

@@ -0,0 +1,23 @@
+{
+  "choices": [
+    {
+      "finish_reason": "stop",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "{\"firstName\":\"David\",\"lastName\":\"(Not provided)\",\"hobby\":\", nature\",\"numCats\":2}",
+        "role": "assistant"
+      }
+    }
+  ],
+  "created": 1746053368,
+  "id": "",
+  "model": "google/gemma-3-4b-it",
+  "object": "chat.completion",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": {
+    "completion_tokens": 35,
+    "prompt_tokens": 32,
+    "total_tokens": 67
+  }
+}

integration-tests/models/__snapshots__/test_json_schema_constrain/test_json_schema_complex.json

@@ -0,0 +1,23 @@
+{
+  "choices": [
+    {
+      "finish_reason": "stop",
+      "index": 0,
+      "logprobs": null,
+      "message": {
+        "content": "{\"name\":\"John Smith\",\"age\":30,\"address\":{\"street\":\"Maple Street\",\"city\":\"Boston\"},\"hobbies\":[\"botany\",\"astronomy\",\"solving mathematical puzzles\"]}",
+        "role": "assistant"
+      }
+    }
+  ],
+  "created": 1746053373,
+  "id": "",
+  "model": "google/gemma-3-4b-it",
+  "object": "chat.completion",
+  "system_fingerprint": "3.2.3-dev0-native",
+  "usage": {
+    "completion_tokens": 44,
+    "prompt_tokens": 37,
+    "total_tokens": 81
+  }
+}