feat: add support for Gemini 3.0 Flash Preview model

- Add gemini-3-flash-preview to GEMINI_MODELS constant in llms/constants.py
- Add context window size (1048576) for gemini-3-flash-preview in llm.py
- Add gemini-3-flash-preview to CLI constants for discoverability
- Add test case and VCR cassette for gemini-3-flash-preview model

Fixes #4308

Co-Authored-By: João <joao@crewai.com>

lib/crewai/src/crewai/cli/constants.py

@@ -145,6 +145,7 @@ MODELS = {
         "claude-3-haiku-20240307",
     ],
     "gemini": [
+        "gemini/gemini-3-flash-preview",
         "gemini/gemini-3-pro-preview",
         "gemini/gemini-1.5-flash",
         "gemini/gemini-1.5-pro",

lib/crewai/src/crewai/llm.py

@@ -200,6 +200,7 @@ LLM_CONTEXT_WINDOW_SIZES: Final[dict[str, int]] = {
     "o3-mini": 200000,
     "o4-mini": 200000,
     # gemini
+    "gemini-3-flash-preview": 1048576,
     "gemini-3-pro-preview": 1048576,
     "gemini-2.0-flash": 1048576,
     "gemini-2.0-flash-thinking-exp-01-21": 32768,

lib/crewai/src/crewai/llms/constants.py

@@ -239,6 +239,7 @@ ANTHROPIC_MODELS: list[AnthropicModels] = [
 ]
 
 GeminiModels: TypeAlias = Literal[
+    "gemini-3-flash-preview",
     "gemini-3-pro-preview",
     "gemini-2.5-pro",
     "gemini-2.5-pro-preview-03-25",
@@ -293,6 +294,7 @@ GeminiModels: TypeAlias = Literal[
     "learnlm-2.0-flash-experimental",
 ]
 GEMINI_MODELS: list[GeminiModels] = [
+    "gemini-3-flash-preview",
     "gemini-3-pro-preview",
     "gemini-2.5-pro",
     "gemini-2.5-pro-preview-03-25",

lib/crewai/tests/cassettes/test_gemini_models[gemini-gemini-3-flash-preview].yaml

@@ -0,0 +1,60 @@
+interactions:
+- request:
+    body: '{"contents": [{"parts": [{"text": "What is the capital of France?"}], "role":
+      "user"}], "generationConfig": {}}'
+    headers:
+      Accept:
+      - '*/*'
+      Accept-Encoding:
+      - gzip, deflate, zstd
+      Connection:
+      - keep-alive
+      Content-Length:
+      - '111'
+      Content-Type:
+      - application/json
+      user-agent:
+      - google-genai-sdk/1.2.0 gl-python/3.12.9
+      x-goog-api-client:
+      - google-genai-sdk/1.2.0 gl-python/3.12.9
+      x-goog-api-key:
+      - X-GOOG-API-KEY-XXX
+    method: POST
+    uri: https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash-preview:generateContent
+  response:
+    body:
+      string: "{\n  \"candidates\": [\n    {\n      \"content\": {\n        \"parts\":
+        [\n          {\n            \"text\": \"The capital of France is **Paris**.\"\n
+        \         }\n        ],\n        \"role\": \"model\"\n      },\n      \"finishReason\":
+        \"STOP\",\n      \"index\": 0\n    }\n  ],\n  \"usageMetadata\": {\n    \"promptTokenCount\":
+        8,\n    \"candidatesTokenCount\": 8,\n    \"totalTokenCount\": 16,\n    \"promptTokensDetails\":
+        [\n      {\n        \"modality\": \"TEXT\",\n        \"tokenCount\": 8\n      }\n
+        \   ]\n  },\n  \"modelVersion\": \"gemini-3-flash-preview\",\n
+        \ \"responseId\": \"xFIrafrxEOag_uMP_ayUwA1\"\n}\n"
+    headers:
+      Alt-Svc:
+      - h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
+      Content-Type:
+      - application/json; charset=UTF-8
+      Date:
+      - Thu, 30 Jan 2026 00:08:00 GMT
+      Server:
+      - scaffolding on HTTPServer2
+      Server-Timing:
+      - gfet4t7; dur=500
+      Transfer-Encoding:
+      - chunked
+      Vary:
+      - Origin
+      - X-Origin
+      - Referer
+      X-Content-Type-Options:
+      - X-CONTENT-TYPE-XXX
+      X-Frame-Options:
+      - X-FRAME-OPTIONS-XXX
+      X-XSS-Protection:
+      - '0'
+    status:
+      code: 200
+      message: OK
+version: 1

lib/crewai/tests/test_llm.py

@@ -264,6 +264,7 @@ def test_validate_call_params_no_response_format():
 @pytest.mark.parametrize(
     "model",
     [
+        "gemini/gemini-3-flash-preview",
         "gemini/gemini-3-pro-preview",
         "gemini/gemini-2.0-flash-thinking-exp-01-21",
         "gemini/gemini-2.0-flash-001",