diff --git a/rig/rig-core/tests/deepseek/agent.rs b/rig/rig-core/tests/deepseek/agent.rs
index 2c808582a..0990d55ac 100644
--- a/rig/rig-core/tests/deepseek/agent.rs
+++ b/rig/rig-core/tests/deepseek/agent.rs
@@ -11,7 +11,7 @@ use crate::support::{BASIC_PREAMBLE, BASIC_PROMPT, assert_nonempty_response};
 async fn completion_smoke() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(deepseek::DEEPSEEK_CHAT)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble(BASIC_PREAMBLE)
         .build();
 
diff --git a/rig/rig-core/tests/deepseek/extractor.rs b/rig/rig-core/tests/deepseek/extractor.rs
index 1549c765a..abc79888c 100644
--- a/rig/rig-core/tests/deepseek/extractor.rs
+++ b/rig/rig-core/tests/deepseek/extractor.rs
@@ -10,7 +10,7 @@ use crate::support::{EXTRACTOR_TEXT, SmokePerson, assert_nonempty_response};
 async fn extractor_smoke() {
     let client = deepseek::Client::from_env().expect("client should build");
     let extractor = client
-        .extractor::<SmokePerson>(deepseek::DEEPSEEK_CHAT)
+        .extractor::<SmokePerson>(deepseek::DEEPSEEK_V4_FLASH)
         .build();
 
     let person = extractor
diff --git a/rig/rig-core/tests/deepseek/extractor_usage.rs b/rig/rig-core/tests/deepseek/extractor_usage.rs
index b2a0c4fd8..6cbbaa9c6 100644
--- a/rig/rig-core/tests/deepseek/extractor_usage.rs
+++ b/rig/rig-core/tests/deepseek/extractor_usage.rs
@@ -41,7 +41,9 @@ fn assert_compatible_professions(left: Option<&str>, right: &str) -> Result<()>
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn extract_backward_compatibility() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
-    let extractor = client.extractor::<Person>(deepseek::DEEPSEEK_CHAT).build();
+    let extractor = client
+        .extractor::<Person>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
 
     let person = extractor
         .extract("John Doe is a 30 year old software engineer.")
@@ -66,7 +68,9 @@ async fn extract_backward_compatibility() -> Result<()> {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn extract_with_usage_returns_data_and_usage() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
-    let extractor = client.extractor::<Person>(deepseek::DEEPSEEK_CHAT).build();
+    let extractor = client
+        .extractor::<Person>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
 
     let response: ExtractionResponse<Person> = extractor
         .extract_with_usage("Jane Smith is a 45 year old data scientist.")
@@ -94,7 +98,9 @@ async fn extract_with_usage_returns_data_and_usage() -> Result<()> {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn extract_with_chat_history_with_usage_works() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
-    let extractor = client.extractor::<Address>(deepseek::DEEPSEEK_CHAT).build();
+    let extractor = client
+        .extractor::<Address>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
 
     let chat_history = vec![Message::user(
         "I'm looking at a property that might be interesting.",
@@ -137,7 +143,9 @@ async fn extract_with_chat_history_with_usage_works() -> Result<()> {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn extract_and_extract_with_usage_return_same_data() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
-    let extractor = client.extractor::<Person>(deepseek::DEEPSEEK_CHAT).build();
+    let extractor = client
+        .extractor::<Person>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
 
     let text = "Bob Johnson is a 55 year old retired teacher.";
     let person = extractor.extract(text).await?;
@@ -175,7 +183,9 @@ async fn extract_and_extract_with_usage_return_same_data() -> Result<()> {
 async fn usage_tracking_works_for_different_schemas() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
 
-    let person_extractor = client.extractor::<Person>(deepseek::DEEPSEEK_CHAT).build();
+    let person_extractor = client
+        .extractor::<Person>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
     let person_response = person_extractor
         .extract_with_usage("Alice is a 25 year old developer.")
         .await?;
@@ -184,7 +194,9 @@ async fn usage_tracking_works_for_different_schemas() -> Result<()> {
         "expected person usage tokens"
     );
 
-    let address_extractor = client.extractor::<Address>(deepseek::DEEPSEEK_CHAT).build();
+    let address_extractor = client
+        .extractor::<Address>(deepseek::DEEPSEEK_V4_FLASH)
+        .build();
     let address_response = address_extractor
         .extract_with_usage("456 Oak Avenue, Cambridge, MA 02139")
         .await?;
diff --git a/rig/rig-core/tests/deepseek/mod.rs b/rig/rig-core/tests/deepseek/mod.rs
index f73aa70a1..5d2a2053c 100644
--- a/rig/rig-core/tests/deepseek/mod.rs
+++ b/rig/rig-core/tests/deepseek/mod.rs
@@ -1,6 +1,7 @@
 mod agent;
 mod extractor;
 mod extractor_usage;
+mod models;
 mod multi_extract;
 mod permission_control;
 mod reasoning_roundtrip;
diff --git a/rig/rig-core/tests/deepseek/models.rs b/rig/rig-core/tests/deepseek/models.rs
new file mode 100644
index 000000000..05c5b7039
--- /dev/null
+++ b/rig/rig-core/tests/deepseek/models.rs
@@ -0,0 +1,33 @@
+//! DeepSeek model listing smoke test.
+//!
+//! Run with:
+//! `cargo test -p rig-core --test deepseek deepseek::models::list_models_smoke -- --ignored --nocapture`
+
+use rig::client::{ModelListingClient, ProviderClient};
+use rig::providers::deepseek;
+
+#[tokio::test]
+#[ignore = "requires DEEPSEEK_API_KEY"]
+async fn list_models_smoke() {
+    let client = deepseek::Client::from_env().expect("client should build");
+    let models = match client.list_models().await {
+        Ok(models) => models,
+        Err(error) => {
+            panic!("listing DeepSeek models should succeed\nDisplay: {error}\nDebug: {error:#?}")
+        }
+    };
+
+    assert!(
+        !models.is_empty(),
+        "expected DeepSeek to return at least one model\nModel list: {models:#?}"
+    );
+
+    assert!(
+        models
+            .iter()
+            .any(|model| model.owned_by.as_deref() == Some("deepseek")),
+        "expected at least one DeepSeek-owned model\nModel list: {models:#?}"
+    );
+
+    println!("DeepSeek returned {} models", models.len());
+}
diff --git a/rig/rig-core/tests/deepseek/multi_extract.rs b/rig/rig-core/tests/deepseek/multi_extract.rs
index 4e0db7ce5..c2e947483 100644
--- a/rig/rig-core/tests/deepseek/multi_extract.rs
+++ b/rig/rig-core/tests/deepseek/multi_extract.rs
@@ -31,17 +31,17 @@ struct Sentiment {
 async fn batch_multi_extract_chain() -> Result<()> {
     let client = deepseek::Client::from_env().expect("client should build");
     let names_extractor = client
-        .extractor::<Names>(deepseek::DEEPSEEK_CHAT)
+        .extractor::<Names>(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("Extract names from the given text.")
         .retries(2)
         .build();
     let topics_extractor = client
-        .extractor::<Topics>(deepseek::DEEPSEEK_CHAT)
+        .extractor::<Topics>(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("Extract topics from the given text.")
         .retries(2)
         .build();
     let sentiment_extractor = client
-        .extractor::<Sentiment>(deepseek::DEEPSEEK_CHAT)
+        .extractor::<Sentiment>(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("Extract sentiment and confidence from the given text.")
         .retries(2)
         .build();
diff --git a/rig/rig-core/tests/deepseek/permission_control.rs b/rig/rig-core/tests/deepseek/permission_control.rs
index b83f9f84e..49defe33c 100644
--- a/rig/rig-core/tests/deepseek/permission_control.rs
+++ b/rig/rig-core/tests/deepseek/permission_control.rs
@@ -155,7 +155,7 @@ async fn permission_control_prompt_example() -> Result<()> {
 
     let agent = deepseek::Client::from_env()
         .expect("client should build")
-        .agent(deepseek::DEEPSEEK_CHAT)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("You are a helpful assistant that can read files using different methods.")
         .tool(ReadFileHead)
         .tool(ReadFileTail)
@@ -197,7 +197,7 @@ async fn permission_control_streaming_example() -> Result<()> {
 
     let agent = deepseek::Client::from_env()
         .expect("client should build")
-        .agent(deepseek::DEEPSEEK_CHAT)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("You are a helpful assistant that can read files using different methods.")
         .tool(ReadFileHead)
         .tool(ReadFileTail)
diff --git a/rig/rig-core/tests/deepseek/reasoning_roundtrip.rs b/rig/rig-core/tests/deepseek/reasoning_roundtrip.rs
index c4c239c63..bff1d8893 100644
--- a/rig/rig-core/tests/deepseek/reasoning_roundtrip.rs
+++ b/rig/rig-core/tests/deepseek/reasoning_roundtrip.rs
@@ -5,13 +5,19 @@ use rig::providers::deepseek;
 
 use crate::reasoning::{self, ReasoningRoundtripAgent};
 
+fn thinking_params() -> serde_json::Value {
+    serde_json::json!({
+        "thinking": { "type": "enabled" }
+    })
+}
+
 #[tokio::test]
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn streaming() {
     let client = deepseek::Client::from_env().expect("client should build");
     reasoning::run_reasoning_roundtrip_streaming(ReasoningRoundtripAgent::new(
-        client.completion_model(deepseek::DEEPSEEK_REASONER),
-        None,
+        client.completion_model(deepseek::DEEPSEEK_V4_FLASH),
+        Some(thinking_params()),
     ))
     .await;
 }
@@ -21,8 +27,8 @@ async fn streaming() {
 async fn nonstreaming() {
     let client = deepseek::Client::from_env().expect("client should build");
     reasoning::run_reasoning_roundtrip_nonstreaming(ReasoningRoundtripAgent::new(
-        client.completion_model(deepseek::DEEPSEEK_REASONER),
-        None,
+        client.completion_model(deepseek::DEEPSEEK_V4_FLASH),
+        Some(thinking_params()),
     ))
     .await;
 }
diff --git a/rig/rig-core/tests/deepseek/reasoning_tool_roundtrip.rs b/rig/rig-core/tests/deepseek/reasoning_tool_roundtrip.rs
index 88c26df1a..c2ea94dcd 100644
--- a/rig/rig-core/tests/deepseek/reasoning_tool_roundtrip.rs
+++ b/rig/rig-core/tests/deepseek/reasoning_tool_roundtrip.rs
@@ -10,16 +10,23 @@ use rig::streaming::StreamingChat;
 
 use crate::reasoning::{self, WeatherTool};
 
+fn thinking_params() -> serde_json::Value {
+    serde_json::json!({
+        "thinking": { "type": "enabled" }
+    })
+}
+
 #[tokio::test]
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn streaming() {
     let call_count = Arc::new(AtomicUsize::new(0));
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(deepseek::DEEPSEEK_REASONER)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble(reasoning::TOOL_SYSTEM_PROMPT)
         .max_tokens(4096)
         .tool(WeatherTool::new(call_count.clone()))
+        .additional_params(thinking_params())
         .build();
 
     let stream = agent
@@ -45,10 +52,11 @@ async fn nonstreaming() {
     let call_count = Arc::new(AtomicUsize::new(0));
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(deepseek::DEEPSEEK_REASONER)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble(reasoning::TOOL_SYSTEM_PROMPT)
         .max_tokens(4096)
         .tool(WeatherTool::new(call_count.clone()))
+        .additional_params(thinking_params())
         .build();
 
     let result = agent
diff --git a/rig/rig-core/tests/deepseek/request_hook.rs b/rig/rig-core/tests/deepseek/request_hook.rs
index 8e1e080d7..2dd356120 100644
--- a/rig/rig-core/tests/deepseek/request_hook.rs
+++ b/rig/rig-core/tests/deepseek/request_hook.rs
@@ -70,7 +70,7 @@ where
 async fn request_hook_records_prompt_and_response() -> Result<()> {
     let agent = deepseek::Client::from_env()
         .expect("client should build")
-        .agent(deepseek::DEEPSEEK_CHAT)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble("You are a comedian here to entertain the user using humour and jokes.")
         .build();
 
diff --git a/rig/rig-core/tests/deepseek/streaming.rs b/rig/rig-core/tests/deepseek/streaming.rs
index 1a7db9b25..8ef14c681 100644
--- a/rig/rig-core/tests/deepseek/streaming.rs
+++ b/rig/rig-core/tests/deepseek/streaming.rs
@@ -1,7 +1,7 @@
 //! DeepSeek streaming smoke test.
 
 use rig::client::{CompletionClient, ProviderClient};
-use rig::providers::deepseek::{self, DEEPSEEK_CHAT};
+use rig::providers::deepseek::{self, DEEPSEEK_V4_FLASH};
 use rig::streaming::StreamingPrompt;
 
 use crate::support::{assert_nonempty_response, collect_stream_final_response};
@@ -11,7 +11,7 @@ use crate::support::{assert_nonempty_response, collect_stream_final_response};
 async fn streaming_prompt_smoke() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(DEEPSEEK_CHAT)
+        .agent(DEEPSEEK_V4_FLASH)
         .preamble("You are a helpful assistant.")
         .build();
 
diff --git a/rig/rig-core/tests/deepseek/streaming_tools.rs b/rig/rig-core/tests/deepseek/streaming_tools.rs
index 5f6954db0..d212ab331 100644
--- a/rig/rig-core/tests/deepseek/streaming_tools.rs
+++ b/rig/rig-core/tests/deepseek/streaming_tools.rs
@@ -4,7 +4,7 @@ use rig::OneOrMany;
 use rig::client::{CompletionClient, ProviderClient};
 use rig::completion::CompletionModel;
 use rig::message::{AssistantContent, Message, ToolChoice};
-use rig::providers::deepseek::{self, DEEPSEEK_CHAT};
+use rig::providers::deepseek::{self, DEEPSEEK_V4_FLASH};
 use rig::streaming::StreamingChat;
 use rig::tool::Tool;
 
@@ -19,16 +19,23 @@ use crate::support::{
     zero_arg_tool_definition,
 };
 
+fn non_thinking_params() -> serde_json::Value {
+    serde_json::json!({
+        "thinking": { "type": "disabled" }
+    })
+}
+
 #[tokio::test]
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn streaming_chat_with_tools() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(DEEPSEEK_CHAT)
+        .agent(DEEPSEEK_V4_FLASH)
         .preamble("You are a calculator here to help the user perform arithmetic operations.")
         .max_tokens(1024)
         .tool(Adder)
         .tool(Subtract)
+        .additional_params(non_thinking_params())
         .build();
 
     let history: &[Message] = &[];
@@ -44,11 +51,12 @@ async fn streaming_chat_with_tools() {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn raw_stream_emits_required_zero_arg_tool_call() {
     let client = deepseek::Client::from_env().expect("client should build");
-    let model = client.completion_model(DEEPSEEK_CHAT);
+    let model = client.completion_model(DEEPSEEK_V4_FLASH);
     let request = model
         .completion_request(REQUIRED_ZERO_ARG_TOOL_PROMPT)
         .tool(zero_arg_tool_definition("ping"))
         .tool_choice(ToolChoice::Required)
+        .additional_params(non_thinking_params())
         .build();
     let stream = model.stream(request).await.expect("stream should start");
 
@@ -59,12 +67,13 @@ async fn raw_stream_emits_required_zero_arg_tool_call() {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn raw_stream_surfaces_two_distinct_tool_calls_before_text() {
     let client = deepseek::Client::from_env().expect("client should build");
-    let model = client.completion_model(DEEPSEEK_CHAT);
+    let model = client.completion_model(DEEPSEEK_V4_FLASH);
     let request = model
         .completion_request(TWO_TOOL_STREAM_PROMPT)
         .preamble(TWO_TOOL_STREAM_PREAMBLE.to_string())
         .tool(AlphaSignal.definition(String::new()).await)
         .tool(BetaSignal.definition(String::new()).await)
+        .additional_params(non_thinking_params())
         .build();
 
     let observation = collect_raw_stream_observation(
@@ -86,10 +95,11 @@ async fn raw_stream_surfaces_two_distinct_tool_calls_before_text() {
 async fn streaming_chat_surfaces_two_distinct_tool_calls_before_final_answer() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(DEEPSEEK_CHAT)
+        .agent(DEEPSEEK_V4_FLASH)
         .preamble(TWO_TOOL_STREAM_PREAMBLE)
         .tool(AlphaSignal)
         .tool(BetaSignal)
+        .additional_params(non_thinking_params())
         .build();
 
     let history: &[Message] = &[];
@@ -111,9 +121,10 @@ async fn streaming_chat_surfaces_two_distinct_tool_calls_before_final_answer() {
 async fn streaming_chat_emits_tool_call_before_later_text() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(DEEPSEEK_CHAT)
+        .agent(DEEPSEEK_V4_FLASH)
         .preamble(ORDERED_TOOL_STREAM_PREAMBLE)
         .tool(AlphaSignal)
+        .additional_params(non_thinking_params())
         .build();
 
     let history: &[Message] = &[];
@@ -134,11 +145,12 @@ async fn streaming_chat_emits_tool_call_before_later_text() {
 #[ignore = "requires DEEPSEEK_API_KEY"]
 async fn raw_followup_uses_tool_result_without_new_tool_calls() {
     let client = deepseek::Client::from_env().expect("client should build");
-    let model = client.completion_model(DEEPSEEK_CHAT);
+    let model = client.completion_model(DEEPSEEK_V4_FLASH);
     let request = model
         .completion_request(ORDERED_TOOL_STREAM_PROMPT)
         .preamble(ORDERED_TOOL_STREAM_PREAMBLE.to_string())
         .tool(AlphaSignal.definition(String::new()).await)
+        .additional_params(non_thinking_params())
         .build();
 
     let first_turn = collect_raw_stream_observation(
@@ -170,6 +182,7 @@ async fn raw_followup_uses_tool_result_without_new_tool_calls() {
         .preamble("Use the provided tool result and answer directly.".to_string())
         .message(assistant_message)
         .message(tool_result_message)
+        .additional_params(non_thinking_params())
         .build();
 
     let second_turn = collect_raw_stream_observation(
diff --git a/rig/rig-core/tests/deepseek/tools.rs b/rig/rig-core/tests/deepseek/tools.rs
index 5e94eb3dc..18fbd8d1d 100644
--- a/rig/rig-core/tests/deepseek/tools.rs
+++ b/rig/rig-core/tests/deepseek/tools.rs
@@ -13,7 +13,7 @@ use crate::support::{
 async fn tools_smoke() {
     let client = deepseek::Client::from_env().expect("client should build");
     let agent = client
-        .agent(deepseek::DEEPSEEK_CHAT)
+        .agent(deepseek::DEEPSEEK_V4_FLASH)
         .preamble(TOOLS_PREAMBLE)
         .tool(Adder)
         .tool(Subtract)