diff --git a/crates/dbx-core/src/ai.rs b/crates/dbx-core/src/ai.rs
index acf0721f68..521c7a6ade 100644
--- a/crates/dbx-core/src/ai.rs
+++ b/crates/dbx-core/src/ai.rs
@@ -447,6 +447,11 @@ pub fn openai_stream_reasoning(event: &serde_json::Value) -> Option<&str> {
 }
 
 pub fn responses_stream_text(event: &serde_json::Value) -> Option<&str> {
+    let event_type = event["type"].as_str().unwrap_or_default();
+    if !event_type.is_empty() && event_type != "response.output_text.delta" {
+        return None;
+    }
+
     event["delta"].as_str().filter(|s| !s.is_empty())
 }
 
@@ -454,6 +459,13 @@ fn responses_max_output_tokens(max_tokens: Option<u32>) -> u32 {
     max_tokens.unwrap_or(2048).max(16)
 }
 
+fn responses_token_usage(event: &serde_json::Value) -> Option<TokenUsage> {
+    let usage = event.get("usage").or_else(|| event.get("response").and_then(|response| response.get("usage")))?;
+    let input = usage.get("input_tokens").and_then(|v| v.as_u64())?;
+    let output = usage.get("output_tokens").and_then(|v| v.as_u64())?;
+    Some(TokenUsage { input_tokens: input as u32, output_tokens: output as u32 })
+}
+
 fn is_openai_api_config(config: &AiConfig) -> bool {
     matches!(config.provider, AiProvider::Openai) || config.endpoint.to_ascii_lowercase().contains("api.openai.com")
 }
@@ -548,6 +560,111 @@ pub fn build_responses_input(system_prompt: &str, messages: &[AiMessage]) -> ser
     json!(input)
 }
 
+fn build_responses_input_with_tools(system_prompt: &str, messages: &[AiMessage]) -> serde_json::Value {
+    let mut input = Vec::new();
+    if !system_prompt.is_empty() {
+        input.push(json!({
+            "role": "developer",
+            "content": system_prompt,
+        }));
+    }
+
+    for message in messages {
+        if message.role == "tool" {
+            input.push(json!({
+                "type": "function_call_output",
+                "call_id": message.tool_call_id.as_deref().unwrap_or_default(),
+                "output": message.content,
+            }));
+            continue;
+        }
+
+        if message.role == "assistant" && !message.tool_calls.is_empty() {
+            if !message.content.is_empty() {
+                input.push(json!({
+                    "role": "assistant",
+                    "content": message.content,
+                }));
+            }
+            for tool_call in &message.tool_calls {
+                input.push(json!({
+                    "type": "function_call",
+                    "call_id": tool_call.id,
+                    "name": tool_call.name,
+                    "arguments": tool_call.arguments.to_string(),
+                }));
+            }
+            continue;
+        }
+
+        input.push(json!({
+            "role": message.role,
+            "content": message.content,
+        }));
+    }
+
+    json!(input)
+}
+
+fn responses_function_tool(tool: &crate::agent_events::ToolDefinition) -> serde_json::Value {
+    json!({
+        "type": "function",
+        "name": tool.name,
+        "description": tool.description,
+        "parameters": tool.parameters,
+    })
+}
+
+fn responses_tool_index(
+    event: &serde_json::Value,
+    item_indices: &mut HashMap<String, u32>,
+    next_index: &mut u32,
+) -> (String, u32) {
+    let item = &event["item"];
+    let item_id = item["id"]
+        .as_str()
+        .or_else(|| event["item_id"].as_str())
+        .map(ToString::to_string)
+        .unwrap_or_else(|| format!("responses-tool-{next_index}"));
+    let index = item_indices.get(&item_id).copied().unwrap_or_else(|| {
+        let index = event["output_index"].as_u64().map(|i| i as u32).unwrap_or(*next_index);
+        *next_index = (*next_index).max(index + 1);
+        item_indices.insert(item_id.clone(), index);
+        index
+    });
+    (item_id, index)
+}
+
+fn emit_responses_function_call_item(
+    event: &serde_json::Value,
+    item_indices: &mut HashMap<String, u32>,
+    started_indices: &mut HashSet<u32>,
+    argument_indices: &mut HashSet<u32>,
+    next_index: &mut u32,
+    on_event: &impl Fn(StreamToolEvent),
+) -> Option<u32> {
+    let item = &event["item"];
+    if item["type"].as_str() != Some("function_call") {
+        return None;
+    }
+
+    let (_item_id, index) = responses_tool_index(event, item_indices, next_index);
+    if started_indices.insert(index) {
+        let id = item["call_id"].as_str().or_else(|| item["id"].as_str()).unwrap_or_default().to_string();
+        let name = item["name"].as_str().unwrap_or_default().to_string();
+        on_event(StreamToolEvent::ToolCallStart { index, id, name });
+    }
+
+    if !argument_indices.contains(&index) {
+        if let Some(arguments) = item["arguments"].as_str().filter(|s| !s.is_empty()) {
+            argument_indices.insert(index);
+            on_event(StreamToolEvent::ToolCallDelta { index, fragment: arguments.to_string() });
+        }
+    }
+
+    Some(index)
+}
+
 // ---------------------------------------------------------------------------
 // Validation helper
 // ---------------------------------------------------------------------------
@@ -1024,15 +1141,24 @@ pub async fn test_connection_core(config: &AiConfig) -> Result<AiTestConnectionR
         }
         _ => {
             // OpenAI-compatible providers
-            let messages = vec![json!({ "role": "user", "content": TEST_PROMPT })];
-            let mut body_obj = json!({
-                "model": &model,
-                "messages": messages,
-                "max_tokens": 16,
-                "stream": true,
-            });
+            let mut body_obj = if config.api_style == AiApiStyle::Responses {
+                json!({
+                    "model": &model,
+                    "input": [{ "role": "user", "content": TEST_PROMPT }],
+                    "max_output_tokens": 16,
+                    "stream": true,
+                })
+            } else {
+                let messages = vec![json!({ "role": "user", "content": TEST_PROMPT })];
+                json!({
+                    "model": &model,
+                    "messages": messages,
+                    "max_tokens": 16,
+                    "stream": true,
+                })
+            };
             add_temperature_if_supported_for_config(&mut body_obj, config, Some(0.0));
-            if !config.enable_thinking && !is_kimi_model(&config.model) {
+            if config.api_style != AiApiStyle::Responses && !config.enable_thinking && !is_kimi_model(&config.model) {
                 body_obj["extra_body"] = json!({
                     "chat_template_kwargs": { "enable_thinking": false }
                 });
@@ -1922,6 +2048,133 @@ async fn stream_openai_with_tools(
     Ok(token_usage)
 }
 
+async fn stream_responses_with_tools(
+    client: &reqwest::Client,
+    session_id: &str,
+    request: &AiCompletionRequest,
+    tools: &[crate::agent_events::ToolDefinition],
+    cancelled: &Notify,
+    on_event: &impl Fn(StreamToolEvent),
+) -> Result<Option<TokenUsage>, String> {
+    let headers = maybe_bearer_headers(&request.config)?;
+    let tool_json: Vec<serde_json::Value> = tools.iter().map(responses_function_tool).collect();
+
+    let mut body = json!({
+        "model": request.config.model,
+        "input": build_responses_input_with_tools(&request.system_prompt, &request.messages),
+        "max_output_tokens": responses_max_output_tokens(request.max_tokens),
+        "tools": tool_json,
+        "tool_choice": "auto",
+        "stream": true,
+    });
+    add_temperature_if_supported(&mut body, request);
+
+    let res = client
+        .post(resolve_endpoint(&request.config))
+        .headers(headers)
+        .json(&body)
+        .send()
+        .await
+        .map_err(|e| format!("AI request failed: {e}"))?;
+
+    if !res.status().is_success() {
+        let data: serde_json::Value = res.json().await.map_err(|e| e.to_string())?;
+        return Err(extract_error(&data).unwrap_or_else(|| "API error".to_string()));
+    }
+
+    let mut byte_stream = res.bytes_stream();
+    let mut buf = Vec::new();
+    let mut item_indices: HashMap<String, u32> = HashMap::new();
+    let mut started_indices: HashSet<u32> = HashSet::new();
+    let mut argument_indices: HashSet<u32> = HashSet::new();
+    let mut next_index: u32 = 0;
+    let mut token_usage: Option<TokenUsage> = None;
+
+    loop {
+        tokio::select! {
+            chunk = byte_stream.next() => {
+                let Some(chunk) = chunk else { break };
+                let chunk = chunk.map_err(|e| e.to_string())?;
+                buf.extend_from_slice(&chunk);
+
+                let mut finished = false;
+                while let Some(line) = drain_next_stream_line(&mut buf)? {
+                    let Some(data) = stream_data_payload(&line) else { continue };
+                    if data == "[DONE]" {
+                        finished = true;
+                        break;
+                    }
+
+                    if let Ok(event) = serde_json::from_str::<serde_json::Value>(data) {
+                        if let Some(usage) = responses_token_usage(&event) {
+                            token_usage = Some(usage);
+                        }
+
+                        if let Some(text) = responses_stream_text(&event) {
+                            on_event(StreamToolEvent::Chunk(AiStreamChunk {
+                                session_id: session_id.to_string(),
+                                delta: text.to_string(),
+                                reasoning_delta: None,
+                                done: false,
+                            }));
+                        }
+
+                        match event["type"].as_str().unwrap_or_default() {
+                            "response.output_item.added" => {
+                                emit_responses_function_call_item(
+                                    &event,
+                                    &mut item_indices,
+                                    &mut started_indices,
+                                    &mut argument_indices,
+                                    &mut next_index,
+                                    on_event,
+                                );
+                            }
+                            "response.output_item.done" => {
+                                if let Some(index) = emit_responses_function_call_item(
+                                    &event,
+                                    &mut item_indices,
+                                    &mut started_indices,
+                                    &mut argument_indices,
+                                    &mut next_index,
+                                    on_event,
+                                ) {
+                                    on_event(StreamToolEvent::ToolCallComplete { index });
+                                }
+                            }
+                            "response.function_call_arguments.delta" => {
+                                let index = event["item_id"]
+                                    .as_str()
+                                    .and_then(|id| item_indices.get(id).copied())
+                                    .or_else(|| event["output_index"].as_u64().map(|i| i as u32))
+                                    .unwrap_or(0);
+                                if let Some(fragment) = event["delta"].as_str() {
+                                    argument_indices.insert(index);
+                                    on_event(StreamToolEvent::ToolCallDelta { index, fragment: fragment.to_string() });
+                                }
+                            }
+                            "response.function_call_arguments.done" => {
+                                let index = event["item_id"]
+                                    .as_str()
+                                    .and_then(|id| item_indices.get(id).copied())
+                                    .or_else(|| event["output_index"].as_u64().map(|i| i as u32))
+                                    .unwrap_or(0);
+                                on_event(StreamToolEvent::ToolCallComplete { index });
+                            }
+                            _ => {}
+                        }
+                    }
+                }
+
+                if finished { break; }
+            }
+            _ = cancelled.notified() => { break; }
+        }
+    }
+
+    Ok(token_usage)
+}
+
 /// Streaming Gemini call with tool support.
 async fn stream_gemini_with_tools(
     client: &reqwest::Client,
@@ -2104,6 +2357,12 @@ pub async fn stream_with_tools(
             })
             .await?
         }
+        _ if config.api_style == AiApiStyle::Responses => {
+            stream_responses_with_tools(&client, session_id, request, tools, cancelled, &|event| {
+                accumulator.lock().unwrap().process(event, &on_chunk);
+            })
+            .await?
+        }
         _ => {
             stream_openai_with_tools(&client, session_id, request, tools, cancelled, &|event| {
                 accumulator.lock().unwrap().process(event, &on_chunk);
@@ -2175,13 +2434,18 @@ pub fn load_config(path: &Path) -> Result<Option<AiConfig>, String> {
 
 #[cfg(test)]
 mod tests {
+    use std::cell::RefCell;
+    use std::collections::{HashMap, HashSet};
+
     use super::{
-        add_temperature_if_supported_for_config, build_ai_http_client, claude_headers, claude_system_prompt,
-        drain_next_stream_line, gemini_text, is_kimi_model, openai_response_text, openai_stream_reasoning,
-        openai_stream_text, parse_model_list_response, resolve_endpoint, resolve_model_list_endpoint,
-        responses_max_output_tokens, responses_text, stream_data_payload, supports_temperature, temperature_value,
-        uses_anthropic_messages_api, validate_config, AiApiStyle, AiAuthMethod, AiConfig, AiModelInfo, AiProvider,
-        AiReasoningLevel, AUTHORIZATION, CLAUDE_DEFAULT_SYSTEM, TEST_PROMPT,
+        add_temperature_if_supported_for_config, build_ai_http_client, build_responses_input_with_tools,
+        claude_headers, claude_system_prompt, drain_next_stream_line, emit_responses_function_call_item, gemini_text,
+        is_kimi_model, openai_response_text, openai_stream_reasoning, openai_stream_text, parse_model_list_response,
+        resolve_endpoint, resolve_model_list_endpoint, responses_function_tool, responses_max_output_tokens,
+        responses_stream_text, responses_text, responses_token_usage, stream_data_payload, supports_temperature,
+        temperature_value, uses_anthropic_messages_api, validate_config, AiApiStyle, AiAuthMethod, AiConfig, AiMessage,
+        AiModelInfo, AiProvider, AiReasoningLevel, StreamToolEvent, StreamingToolCallAccumulator, ToolCallRef,
+        AUTHORIZATION, CLAUDE_DEFAULT_SYSTEM, TEST_PROMPT,
     };
 
     #[test]
@@ -2540,6 +2804,208 @@ mod tests {
         assert_eq!(responses_max_output_tokens(None), 2048);
     }
 
+    #[test]
+    fn responses_stream_text_reads_current_delta_shapes() {
+        assert_eq!(
+            responses_stream_text(&serde_json::json!({
+                "type": "response.output_text.delta",
+                "delta": "SELECT"
+            })),
+            Some("SELECT")
+        );
+        assert_eq!(
+            responses_stream_text(&serde_json::json!({
+                "type": "response.output_text.done",
+                "text": "SELECT 1;"
+            })),
+            None
+        );
+    }
+
+    #[test]
+    fn responses_token_usage_reads_stream_completed_response_usage() {
+        let completed_usage = responses_token_usage(&serde_json::json!({
+            "type": "response.completed",
+            "response": {
+                "usage": {
+                    "input_tokens": 12,
+                    "output_tokens": 34
+                }
+            }
+        }))
+        .unwrap();
+        assert_eq!(completed_usage.input_tokens, 12);
+        assert_eq!(completed_usage.output_tokens, 34);
+
+        let top_level_usage = responses_token_usage(&serde_json::json!({
+            "usage": {
+                "input_tokens": 56,
+                "output_tokens": 78
+            }
+        }))
+        .unwrap();
+        assert_eq!(top_level_usage.input_tokens, 56);
+        assert_eq!(top_level_usage.output_tokens, 78);
+    }
+
+    #[test]
+    fn responses_tools_use_responses_schema() {
+        let input = build_responses_input_with_tools(
+            "system",
+            &[
+                AiMessage {
+                    role: "user".to_string(),
+                    content: "inspect db".to_string(),
+                    tool_call_id: None,
+                    tool_calls: Vec::new(),
+                },
+                AiMessage {
+                    role: "assistant".to_string(),
+                    content: String::new(),
+                    tool_call_id: None,
+                    tool_calls: vec![ToolCallRef {
+                        id: "call_1".to_string(),
+                        name: "list_tables".to_string(),
+                        arguments: serde_json::json!({"schema": "public"}),
+                    }],
+                },
+                AiMessage {
+                    role: "tool".to_string(),
+                    content: "users".to_string(),
+                    tool_call_id: Some("call_1".to_string()),
+                    tool_calls: Vec::new(),
+                },
+            ],
+        );
+
+        assert_eq!(input[0]["role"], "developer");
+        assert_eq!(input[2]["type"], "function_call");
+        assert_eq!(input[2]["call_id"], "call_1");
+        assert_eq!(input[2]["arguments"], "{\"schema\":\"public\"}");
+        assert_eq!(input[3]["type"], "function_call_output");
+        assert_eq!(input[3]["call_id"], "call_1");
+
+        let tool = crate::agent_events::ToolDefinition {
+            name: "list_tables",
+            description: "List tables",
+            parameters: serde_json::json!({"type": "object"}),
+            read_only: true,
+            parallel_ok: true,
+        };
+        let tool_json = responses_function_tool(&tool);
+        assert_eq!(tool_json["type"], "function");
+        assert_eq!(tool_json["name"], "list_tables");
+        assert!(tool_json.get("function").is_none());
+    }
+
+    #[test]
+    fn responses_tool_done_item_can_supply_complete_function_call() {
+        let mut accumulator = StreamingToolCallAccumulator::new();
+        let mut item_indices = HashMap::new();
+        let mut started_indices = HashSet::new();
+        let mut argument_indices = HashSet::new();
+        let mut next_index = 0;
+        let event = serde_json::json!({
+            "type": "response.output_item.done",
+            "output_index": 0,
+            "item": {
+                "id": "fc_1",
+                "type": "function_call",
+                "call_id": "call_1",
+                "name": "list_tables",
+                "arguments": "{\"schema\":\"public\"}"
+            }
+        });
+        let events = RefCell::new(Vec::new());
+        if let Some(index) = emit_responses_function_call_item(
+            &event,
+            &mut item_indices,
+            &mut started_indices,
+            &mut argument_indices,
+            &mut next_index,
+            &|event| events.borrow_mut().push(event),
+        ) {
+            events.borrow_mut().push(StreamToolEvent::ToolCallComplete { index });
+        }
+        for event in events.into_inner() {
+            accumulator.process(event, &|_| {});
+        }
+
+        let calls = accumulator.finalize();
+        assert_eq!(calls.len(), 1);
+        assert_eq!(calls[0].id, "call_1");
+        assert_eq!(calls[0].name, "list_tables");
+        assert_eq!(calls[0].arguments["schema"], "public");
+    }
+
+    #[test]
+    fn responses_tool_arguments_are_not_duplicated_when_done_follows_delta() {
+        let mut accumulator = StreamingToolCallAccumulator::new();
+        let mut item_indices = HashMap::new();
+        let mut started_indices = HashSet::new();
+        let mut argument_indices = HashSet::new();
+        let mut next_index = 0;
+        let added = serde_json::json!({
+            "type": "response.output_item.added",
+            "output_index": 0,
+            "item": {
+                "id": "fc_1",
+                "type": "function_call",
+                "call_id": "call_1",
+                "name": "list_tables"
+            }
+        });
+        let done = serde_json::json!({
+            "type": "response.output_item.done",
+            "output_index": 0,
+            "item": {
+                "id": "fc_1",
+                "type": "function_call",
+                "call_id": "call_1",
+                "name": "list_tables",
+                "arguments": "{\"schema\":\"public\"}"
+            }
+        });
+
+        let events = RefCell::new(Vec::new());
+        emit_responses_function_call_item(
+            &added,
+            &mut item_indices,
+            &mut started_indices,
+            &mut argument_indices,
+            &mut next_index,
+            &|event| events.borrow_mut().push(event),
+        );
+        for event in events.take() {
+            accumulator.process(event, &|_| {});
+        }
+
+        let delta_index = item_indices.get("fc_1").copied().unwrap();
+        argument_indices.insert(delta_index);
+        accumulator.process(
+            StreamToolEvent::ToolCallDelta { index: delta_index, fragment: "{\"schema\":\"public\"}".to_string() },
+            &|_| {},
+        );
+
+        if let Some(index) = emit_responses_function_call_item(
+            &done,
+            &mut item_indices,
+            &mut started_indices,
+            &mut argument_indices,
+            &mut next_index,
+            &|event| events.borrow_mut().push(event),
+        ) {
+            events.borrow_mut().push(StreamToolEvent::ToolCallComplete { index });
+        }
+        for event in events.into_inner() {
+            accumulator.process(event, &|_| {});
+        }
+
+        let calls = accumulator.finalize();
+        assert_eq!(calls.len(), 1);
+        assert_eq!(calls[0].arguments, serde_json::json!({"schema": "public"}));
+    }
+
     #[test]
     fn temperature_value_rounds_f32_to_provider_safe_precision() {
         assert_eq!(temperature_value(Some(0.15)), serde_json::json!(0.15));