feat(model_info): add supports_continuation capability flag for Gemini long decode continuation (#49500)

* feat(model_info): add supports_continuation capability flag for Gemini long decode continuation

* fix(router): keep a deployment's supports_continuation override on that deployment

A supports_continuation value set in one deployment's model_info was written onto the shared provider/model cost map key, so every other deployment of that model reported it too. List it with the other per-deployment capability flags, and cite Google's long decode page next to the cost map assertion

* fix(cost-map): flag vertex_ai/gemini-4-argon-cyber-permissive with supports_continuation

Google's Vertex Gemini 4 Argon guide gives gemini-4-argon-cyber-permissive the same long decode limit as gemini-4-argon, and LiteLLM already continues its long requests, so the cost map now says so in both copies.

* fix(router): count only a boolean true supports_continuation when building a model group

---------

Co-authored-by: mateo-berri <277851410+mateo-berri@users.noreply.github.com>

litellm/__init__.py

@@ -2374,6 +2374,7 @@ if TYPE_CHECKING:
     supports_web_search: Callable[..., bool]
     supports_tool_search: Callable[..., bool]
     supports_url_context: Callable[..., bool]
+    supports_continuation: Callable[..., bool]
     supports_response_schema: Callable[..., bool]
     supports_parallel_function_calling: Callable[..., bool]
     supports_vision: Callable[..., bool]

litellm/_lazy_imports_registry.py

@@ -33,6 +33,7 @@ UTILS_NAMES: Final = (
     "supports_web_search",
     "supports_tool_search",
     "supports_url_context",
+    "supports_continuation",
     "supports_response_schema",
     "supports_parallel_function_calling",
     "supports_vision",
@@ -488,6 +489,7 @@ _UTILS_IMPORT_MAP: Final = {
     "supports_web_search": (".utils", "supports_web_search"),
     "supports_tool_search": (".utils", "supports_tool_search"),
     "supports_url_context": (".utils", "supports_url_context"),
+    "supports_continuation": (".utils", "supports_continuation"),
     "supports_response_schema": (".utils", "supports_response_schema"),
     "supports_parallel_function_calling": (
         ".utils",

litellm/model_prices_and_context_window_backup.json

@@ -76813,6 +76813,7 @@
         "supports_audio_input": true,
         "supports_audio_output": false,
         "supports_computer_use": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,
@@ -76872,6 +76873,7 @@
         ],
         "supports_audio_input": true,
         "supports_computer_use": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,
@@ -76929,6 +76931,7 @@
             "text"
         ],
         "supports_audio_input": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,

litellm/router_python_core.py

@@ -13247,6 +13247,7 @@ class PythonCore(DeprecatedRouterMembers):
                         "providers": [llm_provider],
                         "description": model_group_description,
                         **model_info,
+                        "supports_continuation": model_info.get("supports_continuation") is True,
                         "supports_fast_mode": True,
                         "supported_reasoning_efforts": None,
                         "supported_endpoints": None,
@@ -13314,6 +13315,8 @@ class PythonCore(DeprecatedRouterMembers):
                     and model_info["supports_url_context"] is True
                 ):
                     model_group_info.supports_url_context = True
+                if model_info.get("supports_continuation") is True:
+                    model_group_info.supports_continuation = True
 
                 if model_info.get("supports_reasoning", None) is not None and model_info["supports_reasoning"] is True:
                     model_group_info.supports_reasoning = True

litellm/types/router.py

@@ -1061,6 +1061,7 @@ class ModelGroupInfo(LiteLLMBaseModel):
     supports_vision: bool = Field(default=False)
     supports_web_search: bool = Field(default=False)
     supports_url_context: bool = Field(default=False)
+    supports_continuation: bool = Field(default=False)
     supports_reasoning: bool = Field(default=False)
     supports_function_calling: bool = Field(default=False)
     supports_fast_mode: bool = Field(default=False)

litellm/types/utils.py

@@ -227,6 +227,7 @@ class ProviderSpecificModelInfo(TypedDict, total=False):
     supports_tool_search: bool | None
     supports_mid_conversation_system: bool | None
     supports_url_context: bool | None
+    supports_continuation: ReadOnly[bool | None]
     supports_none_reasoning_effort: bool | None
     supports_minimal_reasoning_effort: bool | None
     supports_low_reasoning_effort: bool | None
@@ -4234,6 +4235,7 @@ DEPLOYMENT_SCOPED_CAPABILITY_FIELDS: Final[frozenset[str]] = frozenset(
         "supports_assistant_prefill",
         "supports_bedrock_native_structured_output",
         "supports_pdf_input",
+        "supports_continuation",
         "reasoning_modes",
         "reasoning_contexts",
     }

litellm/utils.py

@@ -3187,6 +3187,14 @@ def supports_url_context(model: str, custom_llm_provider: str | None = None) ->
     )
 
 
+def supports_continuation(model: str, custom_llm_provider: str | None = None) -> bool:
+    return supports_factory(
+        model=model,
+        custom_llm_provider=custom_llm_provider,
+        key="supports_continuation",
+    )
+
+
 def supports_native_streaming(model: str, custom_llm_provider: str | None) -> bool:
     """
     Check if the given model supports native streaming and return a boolean value.
@@ -7377,6 +7385,7 @@ def get_model_info_helper(
                 ),
                 supports_web_search=_model_info.get("supports_web_search", None),
                 supports_url_context=_model_info.get("supports_url_context", None),
+                supports_continuation=_model_info.get("supports_continuation", None),
                 supports_reasoning=_model_info.get("supports_reasoning", None),
                 supports_adaptive_thinking=_model_info.get("supports_adaptive_thinking", None),
                 supports_legacy_thinking=_model_info.get("supports_legacy_thinking", None),
@@ -7536,6 +7545,7 @@ def get_model_info(
             supports_pdf_input: Optional[bool]
             supports_web_search: Optional[bool]
             supports_url_context: Optional[bool]
+            supports_continuation: Optional[bool]
             supports_reasoning: Optional[bool]
     Raises:
         Exception: If the model is not mapped yet.

model_prices_and_context_window.json

@@ -76813,6 +76813,7 @@
         "supports_audio_input": true,
         "supports_audio_output": false,
         "supports_computer_use": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,
@@ -76872,6 +76873,7 @@
         ],
         "supports_audio_input": true,
         "supports_computer_use": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,
@@ -76929,6 +76931,7 @@
             "text"
         ],
         "supports_audio_input": true,
+        "supports_continuation": true,
         "supports_function_calling": true,
         "supports_minimal_reasoning_effort": false,
         "supports_native_streaming": true,

tests/unit/test_model_prices_and_context_window.py

@@ -845,6 +845,26 @@ def _search_free_requests_rows(path: Path) -> Mapping[str, dict[str, JsonValue]]
     )
 
 
+def _supports_continuation_rows(path: Path) -> frozenset[str]:
+    prices: Final[dict[str, JsonValue]] = TypeAdapter(dict[str, JsonValue]).validate_json(path.read_bytes())
+    return frozenset(
+        key for key, row in prices.items() if isinstance(row, dict) and row.get("supports_continuation") is True
+    )
+
+
+def test_gemini_4_argon_google_rows_carry_supports_continuation_in_both_cost_map_copies() -> None:
+    main_rows: Final = _supports_continuation_rows(PRICES_PATH)
+    # long decode models: https://ai.google.dev/gemini-api/docs/generate-content/long-decode and
+    # https://docs.cloud.google.com/gemini-enterprise-agent-platform/models/guides/gemini-4-argon (2026-11-02)
+    long_decode_rows: Final = {
+        "gemini/gemini-4-argon",
+        "vertex_ai/gemini-4-argon",
+        "vertex_ai/gemini-4-argon-cyber-permissive",
+    }
+    assert long_decode_rows <= main_rows, sorted(main_rows)
+    assert _supports_continuation_rows(BACKUP_PRICES_PATH) == main_rows
+
+
 @pytest.mark.parametrize("path", (PRICES_PATH, BACKUP_PRICES_PATH), ids=("main", "backup"))
 def test_search_free_requests_rows_are_grounding_rows_with_one_allowance_per_group(path: Path) -> None:
     rows = _search_free_requests_rows(path)

tests/unit/test_router/test_router_helper_utils.py

@@ -1497,6 +1497,51 @@ def test_set_model_group_info(model_list, user_facing_model_group_name):
     assert resp.model_group == user_facing_model_group_name
 
 
+def test_set_model_group_info_reports_supports_continuation_when_any_deployment_has_it():
+    router: Final = Router(
+        model_list=[
+            {
+                "model_name": "long-decode",
+                "litellm_params": {"model": "openai/gpt-4.1", "api_key": "fake"},
+            },
+            {
+                "model_name": "long-decode",
+                "litellm_params": {"model": "openai/gpt-4.1-mini", "api_key": "fake"},
+                "model_info": {"supports_continuation": True},
+            },
+            {
+                "model_name": "long-decode",
+                "litellm_params": {"model": "openai/gpt-4.1-nano", "api_key": "fake"},
+            },
+            {
+                "model_name": "plain",
+                "litellm_params": {"model": "openai/gpt-4.1", "api_key": "fake"},
+            },
+        ]
+    )
+    long_decode: Final = router._set_model_group_info(
+        model_group="long-decode", user_facing_model_group_name="long-decode"
+    )
+    plain: Final = router._set_model_group_info(model_group="plain", user_facing_model_group_name="plain")
+    assert long_decode is not None and long_decode.supports_continuation is True
+    assert plain is not None and plain.supports_continuation is False
+
+
+@pytest.mark.parametrize("value", ["maybe", "", ["x"], "true", 1])
+def test_set_model_group_info_counts_only_a_boolean_true_supports_continuation(value: object) -> None:
+    router: Final = Router(
+        model_list=[
+            {
+                "model_name": "long-decode",
+                "litellm_params": {"model": "openai/gpt-4.1", "api_key": "fake"},
+                "model_info": {"supports_continuation": value},
+            },
+        ]
+    )
+    group: Final = router._set_model_group_info(model_group="long-decode", user_facing_model_group_name="long-decode")
+    assert group is not None and group.supports_continuation is False
+
+
 @pytest.mark.asyncio
 async def test_set_response_headers(model_list):
     """Test if the 'set_response_headers' function is working correctly"""

tests/unit/test_router_model_cost_isolation.py

@@ -585,7 +585,10 @@ def test_should_not_pollute_shared_key_with_custom_nonzero_pricing():
     )
 
 
-@pytest.mark.parametrize("flag", ["supports_regex_lookaround", "supports_assistant_prefill", "supports_sampling_params"])
+@pytest.mark.parametrize(
+    "flag",
+    ["supports_regex_lookaround", "supports_assistant_prefill", "supports_sampling_params", "supports_continuation"],
+)
 def test_capability_flag_stays_on_the_deployment_that_set_it(flag: str) -> None:
     """A deployment's capability override must not land on the shared
     ``{provider}/{model}`` key, or every sibling deployment of that model would inherit it."""

tests/unit/test_utils.py

@@ -476,6 +476,34 @@ def test_supports_video_input_reads_its_own_cost_map_flag(
     assert litellm.get_model_info(model)["supports_video_input"] is video_input
 
 
+@pytest.mark.parametrize("continuation", [True, False])
+def test_supports_continuation_reads_its_own_cost_map_flag(
+    local_model_cost_map: None, monkeypatch: pytest.MonkeyPatch, continuation: bool
+) -> None:
+    model: Final = "gemini/continuation-flag-model"
+    monkeypatch.setitem(
+        litellm.model_cost,
+        model,
+        {
+            "litellm_provider": "gemini",
+            "mode": "chat",
+            "supports_continuation": continuation,
+            "supports_url_context": not continuation,
+        },
+    )
+    assert litellm.supports_continuation(model) is continuation
+    assert litellm.get_model_info(model).get("supports_continuation") is continuation
+
+
+def test_supports_continuation_is_unset_when_the_cost_map_omits_it(
+    local_model_cost_map: None, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    model: Final = "gemini/no-continuation-flag-model"
+    monkeypatch.setitem(litellm.model_cost, model, {"litellm_provider": "gemini", "mode": "chat"})
+    assert litellm.supports_continuation(model) is False
+    assert litellm.get_model_info(model).get("supports_continuation") is None
+
+
 def test_get_optional_params_image_gen():
     from litellm.llms.azure.image_generation import AzureGPTImageGenerationConfig
 
@@ -1192,6 +1220,7 @@ _COST_MAP_ROW_SCHEMA: Final = {
             "supports_bedrock_runtime_chat_completions_inline_reasoning": {"type": "boolean"},
             "supports_bedrock_converse_tool_result_images": {"type": "boolean"},
             "supports_url_context": {"type": "boolean"},
+            "supports_continuation": {"type": "boolean"},
             "supports_multimodal": {"type": "boolean"},
             "uses_embed_content": {"type": "boolean"},
             "supports_reasoning": {"type": "boolean"},

ui/litellm-dashboard/src/lib/http/schema.d.ts

@@ -38948,6 +38948,11 @@ export interface components {
              * @default false
              */
             supports_background_chat: boolean;
+            /**
+             * Supports Continuation
+             * @default false
+             */
+            supports_continuation: boolean;
             /**
              * Supports Fast Mode
              * @default false