diff --git a/crates/core/src/observability/atif.rs b/crates/core/src/observability/atif.rs
index 5ebdae8e..f5801551 100644
--- a/crates/core/src/observability/atif.rs
+++ b/crates/core/src/observability/atif.rs
@@ -654,6 +654,63 @@ fn extract_metrics(output: &Json) -> Option<AtifMetrics> {
     })
 }
 
+fn merge_metrics(
+    primary: Option<AtifMetrics>,
+    supplemental: Option<&AtifMetrics>,
+) -> Option<AtifMetrics> {
+    match (primary, supplemental) {
+        (None, None) => None,
+        (Some(metrics), None) => Some(metrics),
+        (None, Some(supplemental)) => Some(supplemental.clone()),
+        (Some(mut metrics), Some(supplemental)) => {
+            merge_metrics_fields(&mut metrics, supplemental);
+            Some(metrics)
+        }
+    }
+}
+
+fn merge_metrics_fields(target: &mut AtifMetrics, supplemental: &AtifMetrics) {
+    if target.prompt_tokens.is_none() {
+        target.prompt_tokens = supplemental.prompt_tokens;
+    }
+    if target.completion_tokens.is_none() {
+        target.completion_tokens = supplemental.completion_tokens;
+    }
+    if target.cached_tokens.is_none() {
+        target.cached_tokens = supplemental.cached_tokens;
+    }
+    if target.cost_usd.is_none() {
+        target.cost_usd = supplemental.cost_usd;
+    }
+    if target.prompt_token_ids.is_none() {
+        target.prompt_token_ids = supplemental.prompt_token_ids.clone();
+    }
+    if target.completion_token_ids.is_none() {
+        target.completion_token_ids = supplemental.completion_token_ids.clone();
+    }
+    if target.logprobs.is_none() {
+        target.logprobs = supplemental.logprobs.clone();
+    }
+    merge_metrics_extra(&mut target.extra, &supplemental.extra);
+}
+
+fn merge_metrics_extra(target: &mut Option<Json>, supplemental: &Option<Json>) {
+    let Some(supplemental) = supplemental else {
+        return;
+    };
+    match (target.as_mut(), supplemental) {
+        (Some(Json::Object(target_object)), Json::Object(supplemental_object)) => {
+            for (key, value) in supplemental_object {
+                target_object
+                    .entry(key.clone())
+                    .or_insert_with(|| value.clone());
+            }
+        }
+        (None, _) => *target = Some(supplemental.clone()),
+        _ => {}
+    }
+}
+
 fn token_usage_object(output: &Json) -> Option<&serde_json::Map<String, Json>> {
     let output = output.as_object()?;
     output
@@ -1071,25 +1128,28 @@ struct EventLookupMaps {
     name_map: std::collections::HashMap<Uuid, String>,
     start_ts_map: std::collections::HashMap<Uuid, DateTime<Utc>>,
     tool_call_ids: std::collections::HashMap<Uuid, String>,
+    suppressed_llm_events: HashSet<Uuid>,
+    supplemental_llm_metrics: HashMap<Uuid, AtifMetrics>,
 }
 
 impl EventLookupMaps {
     fn from_events(events: &[&Event]) -> Self {
-        Self::from_events_with_correlation_events(events, events)
+        Self::from_events_with_correlation_events(events, events, events)
     }
 
     fn from_events_for_agent(events: &[&Event], tree: &AgentScopeTree, agent_uuid: Uuid) -> Self {
-        let correlation_events = events
+        let tool_correlation_events = events
             .iter()
             .copied()
             .filter(|event| tree.owner_agent(event) == Some(agent_uuid))
             .collect::<Vec<_>>();
-        Self::from_events_with_correlation_events(events, &correlation_events)
+        Self::from_events_with_correlation_events(events, events, &tool_correlation_events)
     }
 
     fn from_events_with_correlation_events(
         events: &[&Event],
-        correlation_events: &[&Event],
+        llm_dedupe_events: &[&Event],
+        tool_correlation_events: &[&Event],
     ) -> Self {
         let mut name_map = std::collections::HashMap::new();
         let mut start_ts_map = std::collections::HashMap::new();
@@ -1099,12 +1159,239 @@ impl EventLookupMaps {
                 start_ts_map.insert(event.uuid(), *event.timestamp());
             }
         }
+        let llm_dedupe = build_llm_dedupe(llm_dedupe_events);
         Self {
             name_map,
             start_ts_map,
-            tool_call_ids: build_tool_call_correlations(correlation_events),
+            tool_call_ids: build_tool_call_correlations(tool_correlation_events),
+            suppressed_llm_events: llm_dedupe.suppressed_events,
+            supplemental_llm_metrics: llm_dedupe.supplemental_metrics,
+        }
+    }
+
+    fn should_suppress_llm_event(&self, event: &Event) -> bool {
+        event.category().map(|category| category.as_str()) == Some("llm")
+            && self.suppressed_llm_events.contains(&event.uuid())
+    }
+}
+
+#[derive(Default)]
+struct LlmDedupeLookups {
+    suppressed_events: HashSet<Uuid>,
+    supplemental_metrics: HashMap<Uuid, AtifMetrics>,
+}
+
+#[derive(Default)]
+struct LlmSpanParts<'a> {
+    start: Option<&'a Event>,
+    end: Option<&'a Event>,
+}
+
+#[derive(Debug, Clone)]
+struct LlmSpanCandidate {
+    uuid: Uuid,
+    parent_uuid: Option<Uuid>,
+    start_ts: DateTime<Utc>,
+    end_ts: DateTime<Utc>,
+    request_signature: String,
+    response_signature: String,
+    model_name: Option<String>,
+    fidelity_score: u8,
+    end_metrics: Option<AtifMetrics>,
+    hook_instrumentation: bool,
+    gateway_instrumentation: bool,
+    non_exact_provider_payload: bool,
+}
+
+fn build_llm_dedupe(events: &[&Event]) -> LlmDedupeLookups {
+    let candidates = collect_llm_span_candidates(events);
+    let mut lookups = LlmDedupeLookups::default();
+
+    for (left_idx, left) in candidates.iter().enumerate() {
+        for right in candidates.iter().skip(left_idx + 1) {
+            if same_physical_llm_request(left, right) {
+                suppress_lower_fidelity_llm_span(left, right, &mut lookups);
+            }
         }
     }
+
+    lookups
+}
+
+fn collect_llm_span_candidates(events: &[&Event]) -> Vec<LlmSpanCandidate> {
+    let mut spans: HashMap<Uuid, LlmSpanParts<'_>> = HashMap::new();
+    for event in events {
+        if event.category().map(|category| category.as_str()) != Some("llm") {
+            continue;
+        }
+        let parts = spans.entry(event.uuid()).or_default();
+        match event.scope_category() {
+            Some(crate::api::event::ScopeCategory::Start) => parts.start = Some(event),
+            Some(crate::api::event::ScopeCategory::End) => parts.end = Some(event),
+            None => {}
+        }
+    }
+
+    spans
+        .into_iter()
+        .filter_map(|(uuid, parts)| LlmSpanCandidate::from_events(uuid, parts.start?, parts.end?))
+        .collect()
+}
+
+impl LlmSpanCandidate {
+    fn from_events(uuid: Uuid, start: &Event, end: &Event) -> Option<Self> {
+        let request_signature = start.data().map(llm_request_signature)?;
+        let response_signature = end.data().map(llm_response_signature)?;
+        Some(Self {
+            uuid,
+            parent_uuid: start.parent_uuid().or_else(|| end.parent_uuid()),
+            start_ts: *start.timestamp(),
+            end_ts: *end.timestamp(),
+            request_signature,
+            response_signature,
+            model_name: start
+                .model_name()
+                .or_else(|| end.model_name())
+                .map(ToOwned::to_owned),
+            fidelity_score: llm_event_fidelity_score(start).max(llm_event_fidelity_score(end)),
+            end_metrics: end.data().and_then(extract_metrics),
+            hook_instrumentation: is_hook_instrumented_llm_event(start)
+                || is_hook_instrumented_llm_event(end),
+            gateway_instrumentation: is_gateway_instrumented_llm_event(start)
+                || is_gateway_instrumented_llm_event(end),
+            non_exact_provider_payload: has_non_exact_provider_payload(start)
+                || has_non_exact_provider_payload(end),
+        })
+    }
+}
+
+fn llm_request_signature(input: &Json) -> String {
+    let content = unwrap_llm_request(input);
+    json_to_string(&extract_user_messages(&content))
+}
+
+fn llm_response_signature(output: &Json) -> String {
+    json_to_string(&extract_llm_response_message(output))
+}
+
+fn same_physical_llm_request(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    same_parent(left, right)
+        && compatible_model_names(left, right)
+        && llm_spans_overlap(left, right)
+        && (same_llm_payload_signatures(left, right)
+            || complementary_hook_and_gateway_spans(left, right))
+}
+
+fn same_llm_payload_signatures(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    left.request_signature == right.request_signature
+        && left.response_signature == right.response_signature
+}
+
+fn complementary_hook_and_gateway_spans(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    (left.non_exact_provider_payload && left.hook_instrumentation && right.gateway_instrumentation)
+        || (right.non_exact_provider_payload
+            && right.hook_instrumentation
+            && left.gateway_instrumentation)
+}
+
+fn same_parent(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    left.parent_uuid.is_some() && left.parent_uuid == right.parent_uuid
+}
+
+fn compatible_model_names(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    match (&left.model_name, &right.model_name) {
+        (Some(left_model), Some(right_model)) => left_model == right_model,
+        _ => true,
+    }
+}
+
+fn llm_spans_overlap(left: &LlmSpanCandidate, right: &LlmSpanCandidate) -> bool {
+    left.start_ts <= right.end_ts && right.start_ts <= left.end_ts
+}
+
+fn suppress_lower_fidelity_llm_span(
+    left: &LlmSpanCandidate,
+    right: &LlmSpanCandidate,
+    lookups: &mut LlmDedupeLookups,
+) {
+    match left.fidelity_score.cmp(&right.fidelity_score) {
+        std::cmp::Ordering::Greater => suppress_llm_span(right, left, lookups),
+        std::cmp::Ordering::Less => suppress_llm_span(left, right, lookups),
+        std::cmp::Ordering::Equal => {}
+    }
+}
+
+fn suppress_llm_span(
+    suppressed: &LlmSpanCandidate,
+    canonical: &LlmSpanCandidate,
+    lookups: &mut LlmDedupeLookups,
+) {
+    lookups.suppressed_events.insert(suppressed.uuid);
+    if let Some(metrics) = &suppressed.end_metrics {
+        let entry = lookups
+            .supplemental_metrics
+            .entry(canonical.uuid)
+            .or_default();
+        merge_metrics_fields(entry, metrics);
+    }
+}
+
+fn llm_event_fidelity_score(event: &Event) -> u8 {
+    let Some(metadata) = event.metadata().and_then(Json::as_object) else {
+        return 50;
+    };
+    if metadata
+        .get("projection")
+        .and_then(Json::as_bool)
+        .unwrap_or(false)
+    {
+        return 10;
+    }
+    if has_non_exact_provider_payload(event) {
+        return 30;
+    }
+    if metadata
+        .get("provider_payload_exact")
+        .and_then(Json::as_bool)
+        .unwrap_or(false)
+    {
+        return 100;
+    }
+    if metadata.contains_key("fidelity_source") || metadata.contains_key("api_call_id") {
+        return 95;
+    }
+    if metadata.contains_key("hook_event_name") {
+        return 90;
+    }
+    if is_gateway_instrumented_llm_event(event) {
+        return 50;
+    }
+    50
+}
+
+fn is_hook_instrumented_llm_event(event: &Event) -> bool {
+    event
+        .metadata()
+        .and_then(Json::as_object)
+        .is_some_and(|metadata| metadata.contains_key("hook_event_name"))
+}
+
+fn is_gateway_instrumented_llm_event(event: &Event) -> bool {
+    event
+        .metadata()
+        .and_then(Json::as_object)
+        .is_some_and(|metadata| {
+            metadata.contains_key("gateway_path") || metadata.contains_key("llm_correlation_source")
+        })
+}
+
+fn has_non_exact_provider_payload(event: &Event) -> bool {
+    event
+        .metadata()
+        .and_then(Json::as_object)
+        .and_then(|metadata| metadata.get("provider_payload_exact"))
+        .and_then(Json::as_bool)
+        == Some(false)
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -1416,6 +1703,9 @@ struct DeferredToolObservation {
 
 impl StepConversionState {
     fn handle_event(&mut self, event: &Event, lookups: &EventLookupMaps) {
+        if lookups.should_suppress_llm_event(event) {
+            return;
+        }
         match (
             event.kind(),
             event.scope_category(),
@@ -1712,6 +2002,11 @@ impl StepConversionState {
             "nemo_relay",
         );
 
+        let metrics = merge_metrics(
+            extract_metrics(output),
+            lookups.supplemental_llm_metrics.get(&event.uuid()),
+        );
+
         self.steps.push(AtifStep {
             step_id: 0,
             source: "agent".to_string(),
@@ -1722,7 +2017,7 @@ impl StepConversionState {
             reasoning_content,
             tool_calls,
             observation: None,
-            metrics: extract_metrics(output),
+            metrics,
             llm_call_count: Some(1),
             is_copied_context: None,
             extra: None,
diff --git a/crates/core/tests/unit/atif_tests.rs b/crates/core/tests/unit/atif_tests.rs
index cd36970c..c42d4333 100644
--- a/crates/core/tests/unit/atif_tests.rs
+++ b/crates/core/tests/unit/atif_tests.rs
@@ -1809,6 +1809,271 @@ fn test_exporter_skips_llm_chunk_marks() {
     assert_eq!(trajectory.steps[0].message, json!("agent.status"));
 }
 
+#[test]
+fn test_exporter_dedupes_overlapping_hook_and_gateway_llm_spans() {
+    let exporter = AtifExporter::new("session-1".to_string(), make_agent_info());
+    let base = base_timestamp();
+    let parent_uuid = Uuid::now_v7();
+    let hook_uuid = Uuid::now_v7();
+    let gateway_uuid = Uuid::now_v7();
+    let request = json!({
+        "messages": [{"role": "user", "content": "Reply with exactly dedupe_ok"}],
+        "model": "test-model"
+    });
+
+    let mut hook_start = event_builder(hook_uuid, EventType::Start)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "hook_event_name": "pre_api_request",
+            "api_call_id": "session:task:abcd:api:1",
+            "provider_payload_exact": true
+        }))
+        .input(json!({"content": request.clone(), "headers": {}}))
+        .build();
+    let mut gateway_start = event_builder(gateway_uuid, EventType::Start)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "gateway_path": "/v1/chat/completions",
+            "llm_correlation_source": "pre_llm_call"
+        }))
+        .input(request.clone())
+        .build();
+    let mut gateway_end = event_builder(gateway_uuid, EventType::End)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "gateway_path": "/v1/chat/completions",
+            "llm_correlation_source": "pre_llm_call"
+        }))
+        .output(json!({
+            "choices": [{"message": {"content": "dedupe_ok"}}],
+            "usage": {"prompt_tokens": 7, "completion_tokens": 3, "total_tokens": 10}
+        }))
+        .build();
+    let mut hook_end = event_builder(hook_uuid, EventType::End)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "hook_event_name": "post_api_request",
+            "api_call_id": "session:task:abcd:api:1",
+            "provider_payload_exact": true
+        }))
+        .output(json!({"content": "dedupe_ok"}))
+        .build();
+
+    for (idx, event) in [
+        &mut hook_start,
+        &mut gateway_start,
+        &mut gateway_end,
+        &mut hook_end,
+    ]
+    .into_iter()
+    .enumerate()
+    {
+        set_event_timestamp(event, base + chrono::Duration::milliseconds(idx as i64));
+    }
+
+    {
+        let mut state = exporter.state.lock().unwrap();
+        state
+            .events
+            .extend([hook_start, gateway_start, gateway_end, hook_end]);
+    }
+
+    let trajectory = exporter.export().unwrap();
+    assert_eq!(trajectory.steps.len(), 2);
+    assert_eq!(
+        trajectory.steps[0].message,
+        json!("Reply with exactly dedupe_ok")
+    );
+    assert_eq!(trajectory.steps[1].message, json!("dedupe_ok"));
+    assert_eq!(
+        trajectory.steps[0].extra.as_ref().unwrap()["ancestry"]["function_name"],
+        "openrouter"
+    );
+    assert_eq!(
+        trajectory.steps[1].extra.as_ref().unwrap()["ancestry"]["function_name"],
+        "openrouter"
+    );
+    assert!(!trajectory.steps.iter().any(|step| {
+        step.extra
+            .as_ref()
+            .is_some_and(|extra| extra["ancestry"]["function_name"] == "openai.chat_completions")
+    }));
+    let metrics = trajectory.steps[1].metrics.as_ref().unwrap();
+    assert_eq!(metrics.prompt_tokens, Some(7));
+    assert_eq!(metrics.completion_tokens, Some(3));
+    assert_eq!(metrics.extra.as_ref().unwrap()["total_tokens"], json!(10));
+}
+
+#[test]
+fn test_exporter_prefers_gateway_span_over_non_exact_hook_summary() {
+    let exporter = AtifExporter::new("session-1".to_string(), make_agent_info());
+    let base = base_timestamp();
+    let parent_uuid = Uuid::now_v7();
+    let hook_uuid = Uuid::now_v7();
+    let gateway_uuid = Uuid::now_v7();
+    let request = json!({
+        "messages": [{"role": "user", "content": "Reply with exactly gateway_ok"}],
+        "model": "test-model"
+    });
+
+    let mut hook_start = event_builder(hook_uuid, EventType::Start)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "hook_event_name": "pre_api_request",
+            "fidelity_source": "agent_api_hooks",
+            "provider_payload_exact": false
+        }))
+        .input(json!({
+            "content": {"message_count": 2, "request_char_count": 128},
+            "headers": {}
+        }))
+        .build();
+    let mut gateway_start = event_builder(gateway_uuid, EventType::Start)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({"gateway_path": "/v1/chat/completions"}))
+        .input(json!({"content": request.clone(), "headers": {}}))
+        .build();
+    let mut gateway_end = event_builder(gateway_uuid, EventType::End)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({"gateway_path": "/v1/chat/completions"}))
+        .output(json!({"choices": [{"message": {"content": "gateway_ok"}}]}))
+        .build();
+    let mut hook_end = event_builder(hook_uuid, EventType::End)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .model_name("test-model")
+        .metadata(json!({
+            "hook_event_name": "post_api_request",
+            "fidelity_source": "agent_api_hooks",
+            "provider_payload_exact": false
+        }))
+        .output(json!({"assistant_content_chars": 10, "finish_reason": "stop"}))
+        .build();
+
+    for (idx, event) in [
+        &mut hook_start,
+        &mut gateway_start,
+        &mut gateway_end,
+        &mut hook_end,
+    ]
+    .into_iter()
+    .enumerate()
+    {
+        set_event_timestamp(event, base + chrono::Duration::milliseconds(idx as i64));
+    }
+
+    {
+        let mut state = exporter.state.lock().unwrap();
+        state
+            .events
+            .extend([hook_start, gateway_start, gateway_end, hook_end]);
+    }
+
+    let trajectory = exporter.export().unwrap();
+    assert_eq!(trajectory.steps.len(), 2);
+    assert_eq!(
+        trajectory.steps[0].message,
+        json!("Reply with exactly gateway_ok")
+    );
+    assert_eq!(trajectory.steps[1].message, json!("gateway_ok"));
+    assert!(trajectory.steps.iter().all(|step| {
+        step.extra
+            .as_ref()
+            .is_some_and(|extra| extra["ancestry"]["function_name"] == "openai.chat_completions")
+    }));
+}
+
+#[test]
+fn test_exporter_keeps_sequential_same_content_llm_spans() {
+    let exporter = AtifExporter::new("session-1".to_string(), make_agent_info());
+    let base = base_timestamp();
+    let parent_uuid = Uuid::now_v7();
+    let hook_uuid = Uuid::now_v7();
+    let gateway_uuid = Uuid::now_v7();
+    let request = json!({
+        "messages": [{"role": "user", "content": "Reply with exactly repeat_ok"}],
+        "model": "test-model"
+    });
+
+    let mut hook_start = event_builder(hook_uuid, EventType::Start)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .metadata(json!({"hook_event_name": "pre_api_request"}))
+        .input(request.clone())
+        .build();
+    let mut hook_end = event_builder(hook_uuid, EventType::End)
+        .name("openrouter")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .metadata(json!({"hook_event_name": "post_api_request"}))
+        .output(json!({"content": "repeat_ok"}))
+        .build();
+    let mut gateway_start = event_builder(gateway_uuid, EventType::Start)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .metadata(json!({"gateway_path": "/v1/chat/completions"}))
+        .input(request)
+        .build();
+    let mut gateway_end = event_builder(gateway_uuid, EventType::End)
+        .name("openai.chat_completions")
+        .parent_uuid(parent_uuid)
+        .scope_type(ScopeType::Llm)
+        .metadata(json!({"gateway_path": "/v1/chat/completions"}))
+        .output(json!({"choices": [{"message": {"content": "repeat_ok"}}]}))
+        .build();
+
+    for (idx, event) in [
+        &mut hook_start,
+        &mut hook_end,
+        &mut gateway_start,
+        &mut gateway_end,
+    ]
+    .into_iter()
+    .enumerate()
+    {
+        set_event_timestamp(event, base + chrono::Duration::milliseconds(idx as i64));
+    }
+
+    {
+        let mut state = exporter.state.lock().unwrap();
+        state
+            .events
+            .extend([hook_start, hook_end, gateway_start, gateway_end]);
+    }
+
+    let trajectory = exporter.export().unwrap();
+    assert_eq!(trajectory.steps.len(), 4);
+    assert!(trajectory.steps.iter().any(|step| {
+        step.extra
+            .as_ref()
+            .is_some_and(|extra| extra["ancestry"]["function_name"] == "openai.chat_completions")
+    }));
+}
+
 #[test]
 fn test_trajectory_serde_roundtrip() {
     let trajectory = AtifTrajectory {