feat: telemetry progress

This threads typed hook settings through runtime config, adds a shell-based hook runner, and executes PreToolUse/PostToolUse around each tool call in the conversation loop. The CLI now rebuilds runtimes with settings-derived hook configuration so user-defined Claude hook commands actually run before and after tools.

Constraint: Hook behavior needed to match Claude-style settings.json hooks without broad plugin/MCP parity work in this change
Rejected: Delay hook loading to the tool executor layer | would miss denied tool calls and duplicate runtime policy plumbing
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: Keep hook execution in the runtime loop so permission decisions and tool results remain wrapped by the same conversation semantics
Tested: cargo test; cargo build --release
Not-tested: Real user hook scripts outside the test harness; broader plugin/skills parity

rust/Cargo.lock

@@ -25,6 +25,7 @@ dependencies = [
  "runtime",
  "serde",
  "serde_json",
+ "telemetry",
  "tokio",
 ]
 
@@ -1096,6 +1097,7 @@ dependencies = [
  "serde",
  "serde_json",
  "sha2",
+ "telemetry",
  "tokio",
  "walkdir",
 ]
@@ -1428,6 +1430,14 @@ dependencies = [
  "yaml-rust",
 ]
 
+[[package]]
+name = "telemetry"
+version = "0.1.0"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "thiserror"
 version = "2.0.18"

rust/crates/api/Cargo.toml

@@ -10,6 +10,7 @@ reqwest = { version = "0.12", default-features = false, features = ["json", "rus
 runtime = { path = "../runtime" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+telemetry = { path = "../telemetry" }
 tokio = { version = "1", features = ["io-util", "macros", "net", "rt-multi-thread", "time"] }
 
 [lints]

rust/crates/api/src/client.rs

@@ -2,17 +2,19 @@ use std::collections::VecDeque;
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use runtime::{
-    load_oauth_credentials, save_oauth_credentials, OAuthConfig, OAuthRefreshRequest,
+    format_usd, load_oauth_credentials, pricing_for_model, save_oauth_credentials, OAuthConfig,
-    OAuthTokenExchangeRequest,
+    OAuthRefreshRequest, OAuthTokenExchangeRequest,
 };
 use serde::Deserialize;
+use serde_json::{Map, Value};
+use telemetry::{AnalyticsEvent, AnthropicRequestProfile, ClientIdentity, SessionTracer};
 
 use crate::error::ApiError;
 use crate::sse::SseParser;
 use crate::types::{MessageRequest, MessageResponse, StreamEvent};
 
 const DEFAULT_BASE_URL: &str = "https://api.anthropic.com";
-const ANTHROPIC_VERSION: &str = "2023-06-01";
+const MESSAGES_PATH: &str = "/v1/messages";
 const REQUEST_ID_HEADER: &str = "request-id";
 const ALT_REQUEST_ID_HEADER: &str = "x-request-id";
 const DEFAULT_INITIAL_BACKOFF: Duration = Duration::from_millis(200);
@@ -108,6 +110,8 @@ pub struct AnthropicClient {
     max_retries: u32,
     initial_backoff: Duration,
     max_backoff: Duration,
+    request_profile: AnthropicRequestProfile,
+    session_tracer: Option<SessionTracer>,
 }
 
 impl AnthropicClient {
@@ -120,6 +124,8 @@ impl AnthropicClient {
             max_retries: DEFAULT_MAX_RETRIES,
             initial_backoff: DEFAULT_INITIAL_BACKOFF,
             max_backoff: DEFAULT_MAX_BACKOFF,
+            request_profile: AnthropicRequestProfile::default(),
+            session_tracer: None,
         }
     }
 
@@ -132,6 +138,8 @@ impl AnthropicClient {
             max_retries: DEFAULT_MAX_RETRIES,
             initial_backoff: DEFAULT_INITIAL_BACKOFF,
             max_backoff: DEFAULT_MAX_BACKOFF,
+            request_profile: AnthropicRequestProfile::default(),
+            session_tracer: None,
         }
     }
 
@@ -176,6 +184,39 @@ impl AnthropicClient {
         self
     }
 
+    #[must_use]
+    pub fn with_request_profile(mut self, request_profile: AnthropicRequestProfile) -> Self {
+        self.request_profile = request_profile;
+        self
+    }
+
+    #[must_use]
+    pub fn with_client_identity(mut self, client_identity: ClientIdentity) -> Self {
+        self.request_profile.client_identity = client_identity;
+        self
+    }
+
+    #[must_use]
+    pub fn with_beta(mut self, beta: impl Into<String>) -> Self {
+        let beta = beta.into();
+        if !self.request_profile.betas.contains(&beta) {
+            self.request_profile.betas.push(beta);
+        }
+        self
+    }
+
+    #[must_use]
+    pub fn with_extra_body_param(mut self, key: impl Into<String>, value: Value) -> Self {
+        self.request_profile.extra_body.insert(key.into(), value);
+        self
+    }
+
+    #[must_use]
+    pub fn with_session_tracer(mut self, session_tracer: SessionTracer) -> Self {
+        self.session_tracer = Some(session_tracer);
+        self
+    }
+
     #[must_use]
     pub fn with_retry_policy(
         mut self,
@@ -211,6 +252,7 @@ impl AnthropicClient {
         if response.request_id.is_none() {
             response.request_id = request_id;
         }
+        self.record_response_usage(&response);
         Ok(response)
     }
 
@@ -279,18 +321,30 @@ impl AnthropicClient {
 
         loop {
             attempts += 1;
+            self.record_request_started(request, attempts);
             match self.send_raw_request(request).await {
                 Ok(response) => match expect_success(response).await {
-                    Ok(response) => return Ok(response),
+                    Ok(response) => {
+                        self.record_request_succeeded(request, attempts, &response);
+                        return Ok(response);
+                    }
                     Err(error) if error.is_retryable() && attempts <= self.max_retries + 1 => {
+                        self.record_request_failed(request, attempts, &error);
                         last_error = Some(error);
                     }
-                    Err(error) => return Err(error),
+                    Err(error) => {
+                        self.record_request_failed(request, attempts, &error);
+                        return Err(error);
+                    }
                 },
                 Err(error) if error.is_retryable() && attempts <= self.max_retries + 1 => {
+                    self.record_request_failed(request, attempts, &error);
                     last_error = Some(error);
                 }
-                Err(error) => return Err(error),
+                Err(error) => {
+                    self.record_request_failed(request, attempts, &error);
+                    return Err(error);
+                }
             }
 
             if attempts > self.max_retries {
@@ -310,18 +364,213 @@ impl AnthropicClient {
         &self,
         request: &MessageRequest,
     ) -> Result<reqwest::Response, ApiError> {
-        let request_url = format!("{}/v1/messages", self.base_url.trim_end_matches('/'));
+        let request_url = format!("{}{}", self.base_url.trim_end_matches('/'), MESSAGES_PATH);
-        let request_builder = self
+        let mut request_builder = self
             .http
             .post(&request_url)
-            .header("anthropic-version", ANTHROPIC_VERSION)
             .header("content-type", "application/json");
+        for (name, value) in self.request_profile.header_pairs() {
+            request_builder = request_builder.header(name, value);
+        }
         let mut request_builder = self.auth.apply(request_builder);
 
-        request_builder = request_builder.json(request);
+        let request_body = self.request_profile.render_json_body(request)?;
+        request_builder = request_builder.json(&request_body);
         request_builder.send().await.map_err(ApiError::from)
     }
 
+    fn record_request_started(&self, request: &MessageRequest, attempt: u32) {
+        if let Some(tracer) = &self.session_tracer {
+            tracer.record_http_request_started(
+                attempt,
+                "POST",
+                MESSAGES_PATH,
+                self.request_attributes(request),
+            );
+        }
+    }
+
+    fn record_request_succeeded(
+        &self,
+        request: &MessageRequest,
+        attempt: u32,
+        response: &reqwest::Response,
+    ) {
+        if let Some(tracer) = &self.session_tracer {
+            tracer.record_http_request_succeeded(
+                attempt,
+                "POST",
+                MESSAGES_PATH,
+                response.status().as_u16(),
+                request_id_from_headers(response.headers()),
+                self.request_attributes(request),
+            );
+        }
+    }
+
+    fn record_request_failed(&self, request: &MessageRequest, attempt: u32, error: &ApiError) {
+        if let Some(tracer) = &self.session_tracer {
+            tracer.record_http_request_failed(
+                attempt,
+                "POST",
+                MESSAGES_PATH,
+                error.to_string(),
+                error.is_retryable(),
+                self.error_attributes(request, error),
+            );
+        }
+    }
+
+    fn record_response_usage(&self, response: &MessageResponse) {
+        let Some(tracer) = &self.session_tracer else {
+            return;
+        };
+
+        let cost = response.usage.estimated_cost_usd(&response.model);
+        let pricing_source = if pricing_for_model(&response.model).is_some() {
+            "model-specific"
+        } else {
+            "default-sonnet"
+        };
+
+        let mut properties = Map::new();
+        properties.insert("model".to_string(), Value::String(response.model.clone()));
+        properties.insert(
+            "pricing_source".to_string(),
+            Value::String(pricing_source.to_string()),
+        );
+        properties.insert(
+            "input_tokens".to_string(),
+            Value::from(response.usage.input_tokens),
+        );
+        properties.insert(
+            "output_tokens".to_string(),
+            Value::from(response.usage.output_tokens),
+        );
+        properties.insert(
+            "cache_creation_input_tokens".to_string(),
+            Value::from(response.usage.cache_creation_input_tokens),
+        );
+        properties.insert(
+            "cache_read_input_tokens".to_string(),
+            Value::from(response.usage.cache_read_input_tokens),
+        );
+        properties.insert(
+            "total_tokens".to_string(),
+            Value::from(response.usage.total_tokens()),
+        );
+        properties.insert(
+            "estimated_cost_usd".to_string(),
+            Value::String(format_usd(cost.total_cost_usd())),
+        );
+        properties.insert(
+            "estimated_input_cost_usd".to_string(),
+            Value::String(format_usd(cost.input_cost_usd)),
+        );
+        properties.insert(
+            "estimated_output_cost_usd".to_string(),
+            Value::String(format_usd(cost.output_cost_usd)),
+        );
+        properties.insert(
+            "estimated_cache_creation_cost_usd".to_string(),
+            Value::String(format_usd(cost.cache_creation_cost_usd)),
+        );
+        properties.insert(
+            "estimated_cache_read_cost_usd".to_string(),
+            Value::String(format_usd(cost.cache_read_cost_usd)),
+        );
+        if let Some(request_id) = &response.request_id {
+            properties.insert("request_id".to_string(), Value::String(request_id.clone()));
+        }
+
+        tracer.record_analytics(AnalyticsEvent {
+            namespace: "api".to_string(),
+            action: "message_usage".to_string(),
+            properties,
+        });
+    }
+
+    fn request_attributes(&self, request: &MessageRequest) -> Map<String, Value> {
+        let mut attributes = Map::new();
+        attributes.insert("model".to_string(), Value::String(request.model.clone()));
+        attributes.insert("stream".to_string(), Value::Bool(request.stream));
+        attributes.insert("max_tokens".to_string(), Value::from(request.max_tokens));
+        attributes.insert(
+            "message_count".to_string(),
+            Value::from(u64::try_from(request.messages.len()).unwrap_or(u64::MAX)),
+        );
+        attributes.insert(
+            "tool_count".to_string(),
+            Value::from(
+                u64::try_from(request.tools.as_ref().map_or(0, Vec::len)).unwrap_or(u64::MAX),
+            ),
+        );
+        attributes.insert(
+            "beta_count".to_string(),
+            Value::from(u64::try_from(self.request_profile.betas.len()).unwrap_or(u64::MAX)),
+        );
+        if !self.request_profile.betas.is_empty() {
+            attributes.insert(
+                "betas".to_string(),
+                Value::Array(
+                    self.request_profile
+                        .betas
+                        .iter()
+                        .cloned()
+                        .map(Value::String)
+                        .collect(),
+                ),
+            );
+        }
+        if !self.request_profile.extra_body.is_empty() {
+            attributes.insert(
+                "extra_body_keys".to_string(),
+                Value::Array(
+                    self.request_profile
+                        .extra_body
+                        .keys()
+                        .cloned()
+                        .map(Value::String)
+                        .collect(),
+                ),
+            );
+        }
+        attributes
+    }
+
+    fn error_attributes(&self, request: &MessageRequest, error: &ApiError) -> Map<String, Value> {
+        let mut attributes = self.request_attributes(request);
+        match error {
+            ApiError::Api {
+                status,
+                error_type,
+                message,
+                ..
+            } => {
+                attributes.insert("status".to_string(), Value::from(status.as_u16()));
+                if let Some(error_type) = error_type {
+                    attributes.insert("error_type".to_string(), Value::String(error_type.clone()));
+                }
+                if let Some(message) = message {
+                    attributes.insert("api_message".to_string(), Value::String(message.clone()));
+                }
+            }
+            ApiError::Http(_) => {
+                attributes.insert("error_type".to_string(), Value::String("http".to_string()));
+            }
+            ApiError::Json(_) => {
+                attributes.insert("error_type".to_string(), Value::String("json".to_string()));
+            }
+            _ => {
+                attributes.insert(
+                    "error_type".to_string(),
+                    Value::String("client".to_string()),
+                );
+            }
+        }
+        attributes
+    }
+
     fn backoff_for_attempt(&self, attempt: u32) -> Result<Duration, ApiError> {
         let Some(multiplier) = 1_u32.checked_shl(attempt.saturating_sub(1)) else {
             return Err(ApiError::BackoffOverflow {

rust/crates/api/src/lib.rs

@@ -15,3 +15,9 @@ pub use types::{
     MessageResponse, MessageStartEvent, MessageStopEvent, OutputContentBlock, StreamEvent,
     ToolChoice, ToolDefinition, ToolResultContentBlock, Usage,
 };
+
+pub use telemetry::{
+    AnalyticsEvent, AnthropicRequestProfile, ClientIdentity, JsonlTelemetrySink,
+    MemoryTelemetrySink, SessionTraceRecord, SessionTracer, TelemetryEvent, TelemetrySink,
+    DEFAULT_ANTHROPIC_VERSION,
+};

rust/crates/api/src/types.rs

@@ -1,3 +1,4 @@
+use runtime::{pricing_for_model, TokenUsage, UsageCostEstimate};
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
@@ -150,7 +151,29 @@ pub struct Usage {
 impl Usage {
     #[must_use]
     pub const fn total_tokens(&self) -> u32 {
-        self.input_tokens + self.output_tokens
+        self.input_tokens
+            + self.output_tokens
+            + self.cache_creation_input_tokens
+            + self.cache_read_input_tokens
+    }
+
+    #[must_use]
+    pub const fn token_usage(&self) -> TokenUsage {
+        TokenUsage {
+            input_tokens: self.input_tokens,
+            output_tokens: self.output_tokens,
+            cache_creation_input_tokens: self.cache_creation_input_tokens,
+            cache_read_input_tokens: self.cache_read_input_tokens,
+        }
+    }
+
+    #[must_use]
+    pub fn estimated_cost_usd(&self, model: &str) -> UsageCostEstimate {
+        let usage = self.token_usage();
+        pricing_for_model(model).map_or_else(
+            || usage.estimate_cost_usd(),
+            |pricing| usage.estimate_cost_usd_with_pricing(pricing),
+        )
     }
 }
 
@@ -210,3 +233,47 @@ pub enum StreamEvent {
     ContentBlockStop(ContentBlockStopEvent),
     MessageStop(MessageStopEvent),
 }
+
+#[cfg(test)]
+mod tests {
+    use runtime::format_usd;
+
+    use super::{MessageResponse, Usage};
+
+    #[test]
+    fn usage_total_tokens_includes_cache_tokens() {
+        let usage = Usage {
+            input_tokens: 10,
+            cache_creation_input_tokens: 2,
+            cache_read_input_tokens: 3,
+            output_tokens: 4,
+        };
+
+        assert_eq!(usage.total_tokens(), 19);
+        assert_eq!(usage.token_usage().total_tokens(), 19);
+    }
+
+    #[test]
+    fn message_response_estimates_cost_from_model_usage() {
+        let response = MessageResponse {
+            id: "msg_cost".to_string(),
+            kind: "message".to_string(),
+            role: "assistant".to_string(),
+            content: Vec::new(),
+            model: "claude-sonnet-4-20250514".to_string(),
+            stop_reason: Some("end_turn".to_string()),
+            stop_sequence: None,
+            usage: Usage {
+                input_tokens: 1_000_000,
+                cache_creation_input_tokens: 100_000,
+                cache_read_input_tokens: 200_000,
+                output_tokens: 500_000,
+            },
+            request_id: None,
+        };
+
+        let cost = response.usage.estimated_cost_usd(&response.model);
+        assert_eq!(format_usd(cost.total_cost_usd()), "$54.6750");
+        assert_eq!(response.total_tokens(), 1_800_000);
+    }
+}

rust/crates/api/tests/client_integration.rs

@@ -8,6 +8,7 @@ use api::{
     StreamEvent, ToolChoice, ToolDefinition,
 };
 use serde_json::json;
+use telemetry::{ClientIdentity, MemoryTelemetrySink, SessionTracer, TelemetryEvent};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::TcpListener;
 use tokio::sync::Mutex;
@@ -64,6 +65,18 @@ async fn send_message_posts_json_and_parses_response() {
         request.headers.get("authorization").map(String::as_str),
         Some("Bearer proxy-token")
     );
+    assert_eq!(
+        request.headers.get("anthropic-version").map(String::as_str),
+        Some("2023-06-01")
+    );
+    assert_eq!(
+        request.headers.get("user-agent").map(String::as_str),
+        Some("claude-code/0.1.0")
+    );
+    assert_eq!(
+        request.headers.get("anthropic-beta").map(String::as_str),
+        Some("claude-code-20250219,prompt-caching-scope-2026-01-05")
+    );
     let body: serde_json::Value =
         serde_json::from_str(&request.body).expect("request body should be json");
     assert_eq!(
@@ -73,6 +86,115 @@ async fn send_message_posts_json_and_parses_response() {
     assert!(body.get("stream").is_none());
     assert_eq!(body["tools"][0]["name"], json!("get_weather"));
     assert_eq!(body["tool_choice"]["type"], json!("auto"));
+    assert_eq!(
+        body["betas"],
+        json!(["claude-code-20250219", "prompt-caching-scope-2026-01-05"])
+    );
+}
+
+#[tokio::test]
+async fn send_message_applies_request_profile_and_records_telemetry() {
+    let state = Arc::new(Mutex::new(Vec::<CapturedRequest>::new()));
+    let server = spawn_server(
+        state.clone(),
+        vec![http_response_with_headers(
+            "200 OK",
+            "application/json",
+            concat!(
+                "{",
+                "\"id\":\"msg_profile\",",
+                "\"type\":\"message\",",
+                "\"role\":\"assistant\",",
+                "\"content\":[{\"type\":\"text\",\"text\":\"ok\"}],",
+                "\"model\":\"claude-3-7-sonnet-latest\",",
+                "\"stop_reason\":\"end_turn\",",
+                "\"stop_sequence\":null,",
+                "\"usage\":{\"input_tokens\":1,\"cache_creation_input_tokens\":2,\"cache_read_input_tokens\":3,\"output_tokens\":1}",
+                "}"
+            ),
+            &[("request-id", "req_profile_123")],
+        )],
+    )
+    .await;
+    let sink = Arc::new(MemoryTelemetrySink::default());
+
+    let client = AnthropicClient::new("test-key")
+        .with_base_url(server.base_url())
+        .with_client_identity(ClientIdentity::new("claude-code", "9.9.9").with_runtime("rust-cli"))
+        .with_beta("tools-2026-04-01")
+        .with_extra_body_param("metadata", json!({"source": "clawd-code"}))
+        .with_session_tracer(SessionTracer::new("session-telemetry", sink.clone()));
+
+    let response = client
+        .send_message(&sample_request(false))
+        .await
+        .expect("request should succeed");
+
+    assert_eq!(response.request_id.as_deref(), Some("req_profile_123"));
+
+    let captured = state.lock().await;
+    let request = captured.first().expect("server should capture request");
+    assert_eq!(
+        request.headers.get("anthropic-beta").map(String::as_str),
+        Some("claude-code-20250219,prompt-caching-scope-2026-01-05,tools-2026-04-01")
+    );
+    assert_eq!(
+        request.headers.get("user-agent").map(String::as_str),
+        Some("claude-code/9.9.9")
+    );
+    let body: serde_json::Value =
+        serde_json::from_str(&request.body).expect("request body should be json");
+    assert_eq!(body["metadata"]["source"], json!("clawd-code"));
+    assert_eq!(
+        body["betas"],
+        json!([
+            "claude-code-20250219",
+            "prompt-caching-scope-2026-01-05",
+            "tools-2026-04-01"
+        ])
+    );
+
+    let events = sink.events();
+    assert_eq!(events.len(), 6);
+    assert!(matches!(
+        &events[0],
+        TelemetryEvent::HttpRequestStarted {
+            session_id,
+            attempt: 1,
+            method,
+            path,
+            ..
+        } if session_id == "session-telemetry" && method == "POST" && path == "/v1/messages"
+    ));
+    assert!(matches!(
+        &events[1],
+        TelemetryEvent::SessionTrace(trace) if trace.name == "http_request_started"
+    ));
+    assert!(matches!(
+        &events[2],
+        TelemetryEvent::HttpRequestSucceeded {
+            request_id,
+            status: 200,
+            ..
+        } if request_id.as_deref() == Some("req_profile_123")
+    ));
+    assert!(matches!(
+        &events[3],
+        TelemetryEvent::SessionTrace(trace) if trace.name == "http_request_succeeded"
+    ));
+    assert!(matches!(
+        &events[4],
+        TelemetryEvent::Analytics(event)
+            if event.namespace == "api"
+                && event.action == "message_usage"
+                && event.properties.get("request_id") == Some(&json!("req_profile_123"))
+                && event.properties.get("total_tokens") == Some(&json!(7))
+                && event.properties.get("estimated_cost_usd") == Some(&json!("$0.0001"))
+    ));
+    assert!(matches!(
+        &events[5],
+        TelemetryEvent::SessionTrace(trace) if trace.name == "analytics"
+    ));
 }
 
 #[tokio::test]

rust/crates/runtime/Cargo.toml

@@ -11,6 +11,7 @@ glob = "0.3"
 regex = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+telemetry = { path = "../telemetry" }
 tokio = { version = "1", features = ["io-util", "macros", "process", "rt", "rt-multi-thread", "time"] }
 walkdir = "2"
 

rust/crates/runtime/src/config.rs

@@ -37,6 +37,7 @@ pub struct RuntimeConfig {
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct RuntimeFeatureConfig {
+    hooks: RuntimeHookConfig,
     mcp: McpConfigCollection,
     oauth: Option<OAuthConfig>,
     model: Option<String>,
@@ -44,6 +45,12 @@ pub struct RuntimeFeatureConfig {
     sandbox: SandboxConfig,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct RuntimeHookConfig {
+    pre_tool_use: Vec<String>,
+    post_tool_use: Vec<String>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct McpConfigCollection {
     servers: BTreeMap<String, ScopedMcpServerConfig>,
@@ -221,6 +228,7 @@ impl ConfigLoader {
         let merged_value = JsonValue::Object(merged.clone());
 
         let feature_config = RuntimeFeatureConfig {
+            hooks: parse_optional_hooks_config(&merged_value)?,
             mcp: McpConfigCollection {
                 servers: mcp_servers,
             },
@@ -278,6 +286,11 @@ impl RuntimeConfig {
         &self.feature_config.mcp
     }
 
+    #[must_use]
+    pub fn hooks(&self) -> &RuntimeHookConfig {
+        &self.feature_config.hooks
+    }
+
     #[must_use]
     pub fn oauth(&self) -> Option<&OAuthConfig> {
         self.feature_config.oauth.as_ref()
@@ -300,6 +313,17 @@ impl RuntimeConfig {
 }
 
 impl RuntimeFeatureConfig {
+    #[must_use]
+    pub fn with_hooks(mut self, hooks: RuntimeHookConfig) -> Self {
+        self.hooks = hooks;
+        self
+    }
+
+    #[must_use]
+    pub fn hooks(&self) -> &RuntimeHookConfig {
+        &self.hooks
+    }
+
     #[must_use]
     pub fn mcp(&self) -> &McpConfigCollection {
         &self.mcp
@@ -326,6 +350,26 @@ impl RuntimeFeatureConfig {
     }
 }
 
+impl RuntimeHookConfig {
+    #[must_use]
+    pub fn new(pre_tool_use: Vec<String>, post_tool_use: Vec<String>) -> Self {
+        Self {
+            pre_tool_use,
+            post_tool_use,
+        }
+    }
+
+    #[must_use]
+    pub fn pre_tool_use(&self) -> &[String] {
+        &self.pre_tool_use
+    }
+
+    #[must_use]
+    pub fn post_tool_use(&self) -> &[String] {
+        &self.post_tool_use
+    }
+}
+
 impl McpConfigCollection {
     #[must_use]
     pub fn servers(&self) -> &BTreeMap<String, ScopedMcpServerConfig> {
@@ -424,6 +468,22 @@ fn parse_optional_model(root: &JsonValue) -> Option<String> {
         .map(ToOwned::to_owned)
 }
 
+fn parse_optional_hooks_config(root: &JsonValue) -> Result<RuntimeHookConfig, ConfigError> {
+    let Some(object) = root.as_object() else {
+        return Ok(RuntimeHookConfig::default());
+    };
+    let Some(hooks_value) = object.get("hooks") else {
+        return Ok(RuntimeHookConfig::default());
+    };
+    let hooks = expect_object(hooks_value, "merged settings.hooks")?;
+    Ok(RuntimeHookConfig {
+        pre_tool_use: optional_string_array(hooks, "PreToolUse", "merged settings.hooks")?
+            .unwrap_or_default(),
+        post_tool_use: optional_string_array(hooks, "PostToolUse", "merged settings.hooks")?
+            .unwrap_or_default(),
+    })
+}
+
 fn parse_optional_permission_mode(
     root: &JsonValue,
 ) -> Result<Option<ResolvedPermissionMode>, ConfigError> {
@@ -836,6 +896,8 @@ mod tests {
             .and_then(JsonValue::as_object)
             .expect("hooks object")
             .contains_key("PostToolUse"));
+        assert_eq!(loaded.hooks().pre_tool_use(), &["base".to_string()]);
+        assert_eq!(loaded.hooks().post_tool_use(), &["project".to_string()]);
         assert!(loaded.mcp().get("home").is_some());
         assert!(loaded.mcp().get("project").is_some());
 

rust/crates/runtime/src/conversation.rs

@@ -1,9 +1,14 @@
 use std::collections::BTreeMap;
 use std::fmt::{Display, Formatter};
 
+use serde_json::{Map, Value};
+use telemetry::SessionTracer;
+
 use crate::compact::{
     compact_session, estimate_session_tokens, CompactionConfig, CompactionResult,
 };
+use crate::config::RuntimeFeatureConfig;
+use crate::hooks::{HookRunResult, HookRunner};
 use crate::permissions::{PermissionOutcome, PermissionPolicy, PermissionPrompter};
 use crate::session::{ContentBlock, ConversationMessage, Session};
 use crate::usage::{TokenUsage, UsageTracker};
@@ -94,6 +99,8 @@ pub struct ConversationRuntime<C, T> {
     system_prompt: Vec<String>,
     max_iterations: usize,
     usage_tracker: UsageTracker,
+    hook_runner: HookRunner,
+    session_tracer: Option<SessionTracer>,
 }
 
 impl<C, T> ConversationRuntime<C, T>
@@ -108,6 +115,25 @@ where
         tool_executor: T,
         permission_policy: PermissionPolicy,
         system_prompt: Vec<String>,
+    ) -> Self {
+        Self::new_with_features(
+            session,
+            api_client,
+            tool_executor,
+            permission_policy,
+            system_prompt,
+            &RuntimeFeatureConfig::default(),
+        )
+    }
+
+    #[must_use]
+    pub fn new_with_features(
+        session: Session,
+        api_client: C,
+        tool_executor: T,
+        permission_policy: PermissionPolicy,
+        system_prompt: Vec<String>,
+        feature_config: &RuntimeFeatureConfig,
     ) -> Self {
         let usage_tracker = UsageTracker::from_session(&session);
         Self {
@@ -118,6 +144,8 @@ where
             system_prompt,
             max_iterations: usize::MAX,
             usage_tracker,
+            hook_runner: HookRunner::from_feature_config(feature_config),
+            session_tracer: None,
         }
     }
 
@@ -127,14 +155,23 @@ where
         self
     }
 
+    #[must_use]
+    pub fn with_session_tracer(mut self, session_tracer: SessionTracer) -> Self {
+        self.session_tracer = Some(session_tracer);
+        self
+    }
+
+    #[allow(clippy::too_many_lines)]
     pub fn run_turn(
         &mut self,
         user_input: impl Into<String>,
         mut prompter: Option<&mut dyn PermissionPrompter>,
     ) -> Result<TurnSummary, RuntimeError> {
+        let user_input = user_input.into();
+        self.record_turn_started(&user_input);
         self.session
             .messages
-            .push(ConversationMessage::user_text(user_input.into()));
+            .push(ConversationMessage::user_text(user_input));
 
         let mut assistant_messages = Vec::new();
         let mut tool_results = Vec::new();
@@ -143,17 +180,31 @@ where
         loop {
             iterations += 1;
             if iterations > self.max_iterations {
-                return Err(RuntimeError::new(
+                let error = RuntimeError::new(
                     "conversation loop exceeded the maximum number of iterations",
-                ));
+                );
+                self.record_turn_failed(iterations, &error);
+                return Err(error);
             }
 
             let request = ApiRequest {
                 system_prompt: self.system_prompt.clone(),
                 messages: self.session.messages.clone(),
             };
-            let events = self.api_client.stream(request)?;
+            let events = match self.api_client.stream(request) {
-            let (assistant_message, usage) = build_assistant_message(events)?;
+                Ok(events) => events,
+                Err(error) => {
+                    self.record_turn_failed(iterations, &error);
+                    return Err(error);
+                }
+            };
+            let (assistant_message, usage) = match build_assistant_message(events) {
+                Ok(result) => result,
+                Err(error) => {
+                    self.record_turn_failed(iterations, &error);
+                    return Err(error);
+                }
+            };
             if let Some(usage) = usage {
                 self.usage_tracker.record(usage);
             }
@@ -167,6 +218,11 @@ where
                     _ => None,
                 })
                 .collect::<Vec<_>>();
+            self.record_assistant_iteration(
+                iterations,
+                &assistant_message,
+                pending_tool_uses.len(),
+            );
 
             self.session.messages.push(assistant_message.clone());
             assistant_messages.push(assistant_message);
@@ -176,6 +232,7 @@ where
             }
 
             for (tool_use_id, tool_name, input) in pending_tool_uses {
+                self.record_tool_started(iterations, &tool_name);
                 let permission_outcome = if let Some(prompt) = prompter.as_mut() {
                     self.permission_policy
                         .authorize(&tool_name, &input, Some(*prompt))
@@ -185,36 +242,61 @@ where
 
                 let result_message = match permission_outcome {
                     PermissionOutcome::Allow => {
-                        match self.tool_executor.execute(&tool_name, &input) {
+                        let pre_hook_result = self.hook_runner.run_pre_tool_use(&tool_name, &input);
-                            Ok(output) => ConversationMessage::tool_result(
+                        if pre_hook_result.is_denied() {
+                            let deny_message = format!("PreToolUse hook denied tool `{tool_name}`");
+                            ConversationMessage::tool_result(
+                                tool_use_id,
+                                tool_name,
+                                format_hook_message(&pre_hook_result, &deny_message),
+                                true,
+                            )
+                        } else {
+                            let (mut output, mut is_error) =
+                                match self.tool_executor.execute(&tool_name, &input) {
+                                    Ok(output) => (output, false),
+                                    Err(error) => (error.to_string(), true),
+                                };
+                            output = merge_hook_feedback(pre_hook_result.messages(), output, false);
+
+                            let post_hook_result = self
+                                .hook_runner
+                                .run_post_tool_use(&tool_name, &input, &output, is_error);
+                            if post_hook_result.is_denied() {
+                                is_error = true;
+                            }
+                            output = merge_hook_feedback(
+                                post_hook_result.messages(),
+                                output,
+                                post_hook_result.is_denied(),
+                            );
+
+                            ConversationMessage::tool_result(
                                 tool_use_id,
                                 tool_name,
                                 output,
-                                false,
+                                is_error,
-                            ),
+                            )
-                            Err(error) => ConversationMessage::tool_result(
-                                tool_use_id,
-                                tool_name,
-                                error.to_string(),
-                                true,
-                            ),
                         }
                     }
                     PermissionOutcome::Deny { reason } => {
                         ConversationMessage::tool_result(tool_use_id, tool_name, reason, true)
                     }
                 };
+                self.record_tool_finished(iterations, &result_message);
                 self.session.messages.push(result_message.clone());
                 tool_results.push(result_message);
             }
         }
 
-        Ok(TurnSummary {
+        let summary = TurnSummary {
             assistant_messages,
             tool_results,
             iterations,
             usage: self.usage_tracker.cumulative_usage(),
-        })
+        };
+        self.record_turn_completed(&summary);
+        Ok(summary)
     }
 
     #[must_use]
@@ -241,6 +323,126 @@ where
     pub fn into_session(self) -> Session {
         self.session
     }
+
+    fn record_turn_started(&self, user_input: &str) {
+        if let Some(tracer) = &self.session_tracer {
+            let mut attributes = Map::new();
+            attributes.insert(
+                "message_count_before".to_string(),
+                Value::from(u64::try_from(self.session.messages.len()).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "input_chars".to_string(),
+                Value::from(u64::try_from(user_input.chars().count()).unwrap_or(u64::MAX)),
+            );
+            tracer.record("turn_started", attributes);
+        }
+    }
+
+    fn record_assistant_iteration(
+        &self,
+        iteration: usize,
+        assistant_message: &ConversationMessage,
+        pending_tool_count: usize,
+    ) {
+        if let Some(tracer) = &self.session_tracer {
+            let mut attributes = Map::new();
+            attributes.insert(
+                "iteration".to_string(),
+                Value::from(u64::try_from(iteration).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "block_count".to_string(),
+                Value::from(u64::try_from(assistant_message.blocks.len()).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "pending_tool_count".to_string(),
+                Value::from(u64::try_from(pending_tool_count).unwrap_or(u64::MAX)),
+            );
+            tracer.record("assistant_iteration_completed", attributes);
+        }
+    }
+
+    fn record_tool_started(&self, iteration: usize, tool_name: &str) {
+        if let Some(tracer) = &self.session_tracer {
+            let mut attributes = Map::new();
+            attributes.insert(
+                "iteration".to_string(),
+                Value::from(u64::try_from(iteration).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "tool_name".to_string(),
+                Value::String(tool_name.to_string()),
+            );
+            tracer.record("tool_execution_started", attributes);
+        }
+    }
+
+    fn record_tool_finished(&self, iteration: usize, result_message: &ConversationMessage) {
+        let Some(tracer) = &self.session_tracer else {
+            return;
+        };
+        let Some(ContentBlock::ToolResult {
+            tool_name,
+            is_error,
+            output,
+            ..
+        }) = result_message.blocks.first()
+        else {
+            return;
+        };
+        let mut attributes = Map::new();
+        attributes.insert(
+            "iteration".to_string(),
+            Value::from(u64::try_from(iteration).unwrap_or(u64::MAX)),
+        );
+        attributes.insert("tool_name".to_string(), Value::String(tool_name.clone()));
+        attributes.insert("is_error".to_string(), Value::Bool(*is_error));
+        attributes.insert(
+            "output_chars".to_string(),
+            Value::from(u64::try_from(output.chars().count()).unwrap_or(u64::MAX)),
+        );
+        tracer.record("tool_execution_finished", attributes);
+    }
+
+    fn record_turn_completed(&self, summary: &TurnSummary) {
+        if let Some(tracer) = &self.session_tracer {
+            let mut attributes = Map::new();
+            attributes.insert(
+                "assistant_message_count".to_string(),
+                Value::from(u64::try_from(summary.assistant_messages.len()).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "tool_result_count".to_string(),
+                Value::from(u64::try_from(summary.tool_results.len()).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "iterations".to_string(),
+                Value::from(u64::try_from(summary.iterations).unwrap_or(u64::MAX)),
+            );
+            attributes.insert(
+                "total_input_tokens".to_string(),
+                Value::from(summary.usage.input_tokens),
+            );
+            attributes.insert(
+                "total_output_tokens".to_string(),
+                Value::from(summary.usage.output_tokens),
+            );
+            tracer.record("turn_completed", attributes);
+        }
+    }
+
+    fn record_turn_failed(&self, iteration: usize, error: &RuntimeError) {
+        if let Some(tracer) = &self.session_tracer {
+            let mut attributes = Map::new();
+            attributes.insert(
+                "iteration".to_string(),
+                Value::from(u64::try_from(iteration).unwrap_or(u64::MAX)),
+            );
+            attributes.insert("error".to_string(), Value::String(error.to_string()));
+            tracer.record("turn_failed", attributes);
+        }
+    }
 }
 
 fn build_assistant_message(
@@ -290,6 +492,32 @@ fn flush_text_block(text: &mut String, blocks: &mut Vec<ContentBlock>) {
     }
 }
 
+fn format_hook_message(result: &HookRunResult, fallback: &str) -> String {
+    if result.messages().is_empty() {
+        fallback.to_string()
+    } else {
+        result.messages().join("\n")
+    }
+}
+
+fn merge_hook_feedback(messages: &[String], output: String, denied: bool) -> String {
+    if messages.is_empty() {
+        return output;
+    }
+
+    let mut sections = Vec::new();
+    if !output.trim().is_empty() {
+        sections.push(output);
+    }
+    let label = if denied {
+        "Hook feedback (denied)"
+    } else {
+        "Hook feedback"
+    };
+    sections.push(format!("{label}:\n{}", messages.join("\n")));
+    sections.join("\n\n")
+}
+
 type ToolHandler = Box<dyn FnMut(&str) -> Result<String, ToolError>>;
 
 #[derive(Default)]
@@ -329,6 +557,7 @@ mod tests {
         StaticToolExecutor,
     };
     use crate::compact::CompactionConfig;
+    use crate::config::{RuntimeFeatureConfig, RuntimeHookConfig};
     use crate::permissions::{
         PermissionMode, PermissionPolicy, PermissionPromptDecision, PermissionPrompter,
         PermissionRequest,
@@ -337,6 +566,8 @@ mod tests {
     use crate::session::{ContentBlock, MessageRole, Session};
     use crate::usage::TokenUsage;
     use std::path::PathBuf;
+    use std::sync::Arc;
+    use telemetry::{MemoryTelemetrySink, SessionTracer, TelemetryEvent};
 
     struct ScriptedApiClient {
         call_count: usize,
@@ -449,6 +680,39 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn records_runtime_session_trace_events() {
+        let sink = Arc::new(MemoryTelemetrySink::default());
+        let tracer = SessionTracer::new("session-runtime", sink.clone());
+        let mut runtime = ConversationRuntime::new(
+            Session::new(),
+            ScriptedApiClient { call_count: 0 },
+            StaticToolExecutor::new().register("add", |_input| Ok("4".to_string())),
+            PermissionPolicy::new(PermissionMode::WorkspaceWrite),
+            vec!["system".to_string()],
+        )
+        .with_session_tracer(tracer);
+
+        runtime
+            .run_turn("what is 2 + 2?", Some(&mut PromptAllowOnce))
+            .expect("conversation loop should succeed");
+
+        let events = sink.events();
+        let trace_names = events
+            .iter()
+            .filter_map(|event| match event {
+                TelemetryEvent::SessionTrace(trace) => Some(trace.name.as_str()),
+                _ => None,
+            })
+            .collect::<Vec<_>>();
+
+        assert!(trace_names.contains(&"turn_started"));
+        assert!(trace_names.contains(&"assistant_iteration_completed"));
+        assert!(trace_names.contains(&"tool_execution_started"));
+        assert!(trace_names.contains(&"tool_execution_finished"));
+        assert!(trace_names.contains(&"turn_completed"));
+    }
+
     #[test]
     fn records_denied_tool_results_when_prompt_rejects() {
         struct RejectPrompter;
@@ -503,6 +767,141 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn denies_tool_use_when_pre_tool_hook_blocks() {
+        struct SingleCallApiClient;
+        impl ApiClient for SingleCallApiClient {
+            fn stream(&mut self, request: ApiRequest) -> Result<Vec<AssistantEvent>, RuntimeError> {
+                if request
+                    .messages
+                    .iter()
+                    .any(|message| message.role == MessageRole::Tool)
+                {
+                    return Ok(vec![
+                        AssistantEvent::TextDelta("blocked".to_string()),
+                        AssistantEvent::MessageStop,
+                    ]);
+                }
+                Ok(vec![
+                    AssistantEvent::ToolUse {
+                        id: "tool-1".to_string(),
+                        name: "blocked".to_string(),
+                        input: r#"{"path":"secret.txt"}"#.to_string(),
+                    },
+                    AssistantEvent::MessageStop,
+                ])
+            }
+        }
+
+        let mut runtime = ConversationRuntime::new_with_features(
+            Session::new(),
+            SingleCallApiClient,
+            StaticToolExecutor::new().register("blocked", |_input| {
+                panic!("tool should not execute when hook denies")
+            }),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
+            vec!["system".to_string()],
+            &RuntimeFeatureConfig::default().with_hooks(RuntimeHookConfig::new(
+                vec![shell_snippet("printf 'blocked by hook'; exit 2")],
+                Vec::new(),
+            )),
+        );
+
+        let summary = runtime
+            .run_turn("use the tool", None)
+            .expect("conversation should continue after hook denial");
+
+        assert_eq!(summary.tool_results.len(), 1);
+        let ContentBlock::ToolResult {
+            is_error, output, ..
+        } = &summary.tool_results[0].blocks[0]
+        else {
+            panic!("expected tool result block");
+        };
+        assert!(
+            *is_error,
+            "hook denial should produce an error result: {output}"
+        );
+        assert!(
+            output.contains("denied tool") || output.contains("blocked by hook"),
+            "unexpected hook denial output: {output:?}"
+        );
+    }
+
+    #[test]
+    fn appends_post_tool_hook_feedback_to_tool_result() {
+        struct TwoCallApiClient {
+            calls: usize,
+        }
+
+        impl ApiClient for TwoCallApiClient {
+            fn stream(&mut self, request: ApiRequest) -> Result<Vec<AssistantEvent>, RuntimeError> {
+                self.calls += 1;
+                match self.calls {
+                    1 => Ok(vec![
+                        AssistantEvent::ToolUse {
+                            id: "tool-1".to_string(),
+                            name: "add".to_string(),
+                            input: r#"{"lhs":2,"rhs":2}"#.to_string(),
+                        },
+                        AssistantEvent::MessageStop,
+                    ]),
+                    2 => {
+                        assert!(request
+                            .messages
+                            .iter()
+                            .any(|message| message.role == MessageRole::Tool));
+                        Ok(vec![
+                            AssistantEvent::TextDelta("done".to_string()),
+                            AssistantEvent::MessageStop,
+                        ])
+                    }
+                    _ => Err(RuntimeError::new("unexpected extra API call")),
+                }
+            }
+        }
+
+        let mut runtime = ConversationRuntime::new_with_features(
+            Session::new(),
+            TwoCallApiClient { calls: 0 },
+            StaticToolExecutor::new().register("add", |_input| Ok("4".to_string())),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
+            vec!["system".to_string()],
+            &RuntimeFeatureConfig::default().with_hooks(RuntimeHookConfig::new(
+                vec![shell_snippet("printf 'pre hook ran'")],
+                vec![shell_snippet("printf 'post hook ran'")],
+            )),
+        );
+
+        let summary = runtime
+            .run_turn("use add", None)
+            .expect("tool loop succeeds");
+
+        assert_eq!(summary.tool_results.len(), 1);
+        let ContentBlock::ToolResult {
+            is_error, output, ..
+        } = &summary.tool_results[0].blocks[0]
+        else {
+            panic!("expected tool result block");
+        };
+        assert!(
+            !*is_error,
+            "post hook should preserve non-error result: {output:?}"
+        );
+        assert!(
+            output.contains('4'),
+            "tool output missing value: {output:?}"
+        );
+        assert!(
+            output.contains("pre hook ran"),
+            "tool output missing pre hook feedback: {output:?}"
+        );
+        assert!(
+            output.contains("post hook ran"),
+            "tool output missing post hook feedback: {output:?}"
+        );
+    }
+
     #[test]
     fn reconstructs_usage_tracker_from_restored_session() {
         struct SimpleApi;
@@ -581,4 +980,14 @@ mod tests {
             MessageRole::System
         );
     }
+
+    #[cfg(windows)]
+    fn shell_snippet(script: &str) -> String {
+        script.replace('\'', "\"")
+    }
+
+    #[cfg(not(windows))]
+    fn shell_snippet(script: &str) -> String {
+        script.to_string()
+    }
 }

rust/crates/runtime/src/hooks.rs

@@ -0,0 +1,353 @@
+use std::ffi::OsStr;
+use std::process::Command;
+
+use serde_json::json;
+
+use crate::config::{RuntimeFeatureConfig, RuntimeHookConfig};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum HookEvent {
+    PreToolUse,
+    PostToolUse,
+}
+
+impl HookEvent {
+    fn as_str(self) -> &'static str {
+        match self {
+            Self::PreToolUse => "PreToolUse",
+            Self::PostToolUse => "PostToolUse",
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct HookRunResult {
+    denied: bool,
+    messages: Vec<String>,
+}
+
+impl HookRunResult {
+    #[must_use]
+    pub fn allow(messages: Vec<String>) -> Self {
+        Self {
+            denied: false,
+            messages,
+        }
+    }
+
+    #[must_use]
+    pub fn is_denied(&self) -> bool {
+        self.denied
+    }
+
+    #[must_use]
+    pub fn messages(&self) -> &[String] {
+        &self.messages
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct HookRunner {
+    config: RuntimeHookConfig,
+}
+
+impl HookRunner {
+    #[must_use]
+    pub fn new(config: RuntimeHookConfig) -> Self {
+        Self { config }
+    }
+
+    #[must_use]
+    pub fn from_feature_config(feature_config: &RuntimeFeatureConfig) -> Self {
+        Self::new(feature_config.hooks().clone())
+    }
+
+    #[must_use]
+    pub fn run_pre_tool_use(&self, tool_name: &str, tool_input: &str) -> HookRunResult {
+        Self::run_commands(
+            HookEvent::PreToolUse,
+            self.config.pre_tool_use(),
+            tool_name,
+            tool_input,
+            None,
+            false,
+        )
+    }
+
+    #[must_use]
+    pub fn run_post_tool_use(
+        &self,
+        tool_name: &str,
+        tool_input: &str,
+        tool_output: &str,
+        is_error: bool,
+    ) -> HookRunResult {
+        Self::run_commands(
+            HookEvent::PostToolUse,
+            self.config.post_tool_use(),
+            tool_name,
+            tool_input,
+            Some(tool_output),
+            is_error,
+        )
+    }
+
+    fn run_commands(
+        event: HookEvent,
+        commands: &[String],
+        tool_name: &str,
+        tool_input: &str,
+        tool_output: Option<&str>,
+        is_error: bool,
+    ) -> HookRunResult {
+        if commands.is_empty() {
+            return HookRunResult::allow(Vec::new());
+        }
+
+        let payload = json!({
+            "hook_event_name": event.as_str(),
+            "tool_name": tool_name,
+            "tool_input": parse_tool_input(tool_input),
+            "tool_input_json": tool_input,
+            "tool_output": tool_output,
+            "tool_result_is_error": is_error,
+        })
+        .to_string();
+        let invocation = HookInvocation {
+            event,
+            tool_name,
+            tool_input,
+            tool_output,
+            is_error,
+            payload: &payload,
+        };
+
+        let mut messages = Vec::new();
+
+        for command in commands {
+            match Self::run_command(command, &invocation) {
+                HookCommandOutcome::Allow { message } => {
+                    if let Some(message) = message {
+                        messages.push(message);
+                    }
+                }
+                HookCommandOutcome::Deny { message } => {
+                    let message = message.unwrap_or_else(|| {
+                        format!("{} hook denied tool `{tool_name}`", event.as_str())
+                    });
+                    messages.push(message);
+                    return HookRunResult {
+                        denied: true,
+                        messages,
+                    };
+                }
+                HookCommandOutcome::Warn { message } => messages.push(message),
+            }
+        }
+
+        HookRunResult::allow(messages)
+    }
+
+    fn run_command(command: &str, invocation: &HookInvocation<'_>) -> HookCommandOutcome {
+        let mut child = shell_command(command);
+        child.stdin(std::process::Stdio::piped());
+        child.stdout(std::process::Stdio::piped());
+        child.stderr(std::process::Stdio::piped());
+        child.env("HOOK_EVENT", invocation.event.as_str());
+        child.env("HOOK_TOOL_NAME", invocation.tool_name);
+        child.env("HOOK_TOOL_INPUT", invocation.tool_input);
+        child.env(
+            "HOOK_TOOL_IS_ERROR",
+            if invocation.is_error { "1" } else { "0" },
+        );
+        if let Some(tool_output) = invocation.tool_output {
+            child.env("HOOK_TOOL_OUTPUT", tool_output);
+        }
+
+        match child.output_with_stdin(invocation.payload.as_bytes()) {
+            Ok(output) => {
+                let stdout = String::from_utf8_lossy(&output.stdout).trim().to_string();
+                let stderr = String::from_utf8_lossy(&output.stderr).trim().to_string();
+                let message = (!stdout.is_empty()).then_some(stdout);
+                match output.status.code() {
+                    Some(0) => HookCommandOutcome::Allow { message },
+                    Some(2) => HookCommandOutcome::Deny { message },
+                    Some(code) => HookCommandOutcome::Warn {
+                        message: format_hook_warning(
+                            command,
+                            code,
+                            message.as_deref(),
+                            stderr.as_str(),
+                        ),
+                    },
+                    None => HookCommandOutcome::Warn {
+                        message: format!(
+                            "{} hook `{command}` terminated by signal while handling `{}`",
+                            invocation.event.as_str(),
+                            invocation.tool_name
+                        ),
+                    },
+                }
+            }
+            Err(error) => HookCommandOutcome::Warn {
+                message: format!(
+                    "{} hook `{command}` failed to start for `{tool_name}`: {error}",
+                    invocation.event.as_str(),
+                    tool_name = invocation.tool_name
+                ),
+            },
+        }
+    }
+}
+
+struct HookInvocation<'a> {
+    event: HookEvent,
+    tool_name: &'a str,
+    tool_input: &'a str,
+    tool_output: Option<&'a str>,
+    is_error: bool,
+    payload: &'a str,
+}
+
+enum HookCommandOutcome {
+    Allow { message: Option<String> },
+    Deny { message: Option<String> },
+    Warn { message: String },
+}
+
+fn parse_tool_input(tool_input: &str) -> serde_json::Value {
+    serde_json::from_str(tool_input).unwrap_or_else(|_| json!({ "raw": tool_input }))
+}
+
+fn format_hook_warning(command: &str, code: i32, stdout: Option<&str>, stderr: &str) -> String {
+    let mut message =
+        format!("Hook `{command}` exited with status {code}; allowing tool execution to continue");
+    if let Some(stdout) = stdout.filter(|stdout| !stdout.is_empty()) {
+        message.push_str(": ");
+        message.push_str(stdout);
+    } else if !stderr.is_empty() {
+        message.push_str(": ");
+        message.push_str(stderr);
+    }
+    message
+}
+
+fn shell_command(command: &str) -> CommandWithStdin {
+    #[cfg(windows)]
+    let mut command_builder = {
+        let mut command_builder = Command::new("cmd");
+        command_builder.arg("/C").arg(command);
+        CommandWithStdin::new(command_builder)
+    };
+
+    #[cfg(not(windows))]
+    let command_builder = {
+        let mut command_builder = Command::new("sh");
+        command_builder.arg("-lc").arg(command);
+        CommandWithStdin::new(command_builder)
+    };
+
+    command_builder
+}
+
+struct CommandWithStdin {
+    command: Command,
+}
+
+impl CommandWithStdin {
+    fn new(command: Command) -> Self {
+        Self { command }
+    }
+
+    fn stdin(&mut self, cfg: std::process::Stdio) -> &mut Self {
+        self.command.stdin(cfg);
+        self
+    }
+
+    fn stdout(&mut self, cfg: std::process::Stdio) -> &mut Self {
+        self.command.stdout(cfg);
+        self
+    }
+
+    fn stderr(&mut self, cfg: std::process::Stdio) -> &mut Self {
+        self.command.stderr(cfg);
+        self
+    }
+
+    fn env<K, V>(&mut self, key: K, value: V) -> &mut Self
+    where
+        K: AsRef<OsStr>,
+        V: AsRef<OsStr>,
+    {
+        self.command.env(key, value);
+        self
+    }
+
+    fn output_with_stdin(&mut self, stdin: &[u8]) -> std::io::Result<std::process::Output> {
+        let mut child = self.command.spawn()?;
+        if let Some(mut child_stdin) = child.stdin.take() {
+            use std::io::Write;
+            child_stdin.write_all(stdin)?;
+        }
+        child.wait_with_output()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{HookRunResult, HookRunner};
+    use crate::config::{RuntimeFeatureConfig, RuntimeHookConfig};
+
+    #[test]
+    fn allows_exit_code_zero_and_captures_stdout() {
+        let runner = HookRunner::new(RuntimeHookConfig::new(
+            vec![shell_snippet("printf 'pre ok'")],
+            Vec::new(),
+        ));
+
+        let result = runner.run_pre_tool_use("Read", r#"{"path":"README.md"}"#);
+
+        assert_eq!(result, HookRunResult::allow(vec!["pre ok".to_string()]));
+    }
+
+    #[test]
+    fn denies_exit_code_two() {
+        let runner = HookRunner::new(RuntimeHookConfig::new(
+            vec![shell_snippet("printf 'blocked by hook'; exit 2")],
+            Vec::new(),
+        ));
+
+        let result = runner.run_pre_tool_use("Bash", r#"{"command":"pwd"}"#);
+
+        assert!(result.is_denied());
+        assert_eq!(result.messages(), &["blocked by hook".to_string()]);
+    }
+
+    #[test]
+    fn warns_for_other_non_zero_statuses() {
+        let runner = HookRunner::from_feature_config(&RuntimeFeatureConfig::default().with_hooks(
+            RuntimeHookConfig::new(
+                vec![shell_snippet("printf 'warning hook'; exit 1")],
+                Vec::new(),
+            ),
+        ));
+
+        let result = runner.run_pre_tool_use("Edit", r#"{"file":"src/lib.rs"}"#);
+
+        assert!(!result.is_denied());
+        assert!(result
+            .messages()
+            .iter()
+            .any(|message| message.contains("allowing tool execution to continue")));
+    }
+
+    #[cfg(windows)]
+    fn shell_snippet(script: &str) -> String {
+        script.replace('\'', "\"")
+    }
+
+    #[cfg(not(windows))]
+    fn shell_snippet(script: &str) -> String {
+        script.to_string()
+    }
+}

rust/crates/runtime/src/lib.rs

@@ -4,6 +4,7 @@ mod compact;
 mod config;
 mod conversation;
 mod file_ops;
+mod hooks;
 mod json;
 mod mcp;
 mod mcp_client;
@@ -26,8 +27,8 @@ pub use config::{
     ConfigEntry, ConfigError, ConfigLoader, ConfigSource, McpClaudeAiProxyServerConfig,
     McpConfigCollection, McpOAuthConfig, McpRemoteServerConfig, McpSdkServerConfig,
     McpServerConfig, McpStdioServerConfig, McpTransport, McpWebSocketServerConfig, OAuthConfig,
-    ResolvedPermissionMode, RuntimeConfig, RuntimeFeatureConfig, ScopedMcpServerConfig,
+    ResolvedPermissionMode, RuntimeConfig, RuntimeFeatureConfig, RuntimeHookConfig,
-    CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+    ScopedMcpServerConfig, CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
 };
 pub use conversation::{
     ApiClient, ApiRequest, AssistantEvent, ConversationRuntime, RuntimeError, StaticToolExecutor,
@@ -38,6 +39,7 @@ pub use file_ops::{
     GrepSearchInput, GrepSearchOutput, ReadFileOutput, StructuredPatchHunk, TextFilePayload,
     WriteFileOutput,
 };
+pub use hooks::{HookEvent, HookRunResult, HookRunner};
 pub use mcp::{
     mcp_server_signature, mcp_tool_name, mcp_tool_prefix, normalize_name_for_mcp,
     scoped_mcp_config_hash, unwrap_ccr_proxy_url,

rust/crates/runtime/src/mcp_stdio.rs

@@ -1144,8 +1144,20 @@ mod tests {
     }
 
     fn cleanup_script(script_path: &Path) {
-        fs::remove_file(script_path).expect("cleanup script");
+        if let Err(error) = fs::remove_file(script_path) {
-        fs::remove_dir_all(script_path.parent().expect("script parent")).expect("cleanup dir");
+            assert_eq!(
+                error.kind(),
+                std::io::ErrorKind::NotFound,
+                "cleanup script: {error}"
+            );
+        }
+        if let Err(error) = fs::remove_dir_all(script_path.parent().expect("script parent")) {
+            assert_eq!(
+                error.kind(),
+                std::io::ErrorKind::NotFound,
+                "cleanup dir: {error}"
+            );
+        }
     }
 
     fn manager_server_config(

rust/crates/rusty-claude-cli/src/main.rs

@@ -4,6 +4,7 @@ mod render;
 
 use std::collections::{BTreeMap, BTreeSet};
 use std::env;
+use std::fmt::Write as _;
 use std::fs;
 use std::io::{self, Read, Write};
 use std::net::TcpListener;
@@ -13,8 +14,9 @@ use std::time::{SystemTime, UNIX_EPOCH};
 
 use api::{
     resolve_startup_auth_source, AnthropicClient, AuthSource, ContentBlockDelta, InputContentBlock,
-    InputMessage, MessageRequest, MessageResponse, OutputContentBlock,
+    InputMessage, JsonlTelemetrySink, MessageRequest, MessageResponse, OutputContentBlock,
-    StreamEvent as ApiStreamEvent, ToolChoice, ToolDefinition, ToolResultContentBlock,
+    SessionTracer, StreamEvent as ApiStreamEvent, ToolChoice, ToolDefinition,
+    ToolResultContentBlock,
 };
 
 use commands::{
@@ -27,8 +29,8 @@ use runtime::{
     clear_oauth_credentials, generate_pkce_pair, generate_state, load_system_prompt,
     parse_oauth_callback_request_target, save_oauth_credentials, ApiClient, ApiRequest,
     AssistantEvent, CompactionConfig, ConfigLoader, ConfigSource, ContentBlock,
-    ConversationMessage, ConversationRuntime, MessageRole, OAuthAuthorizationRequest,
+    ConversationMessage, ConversationRuntime, MessageRole, OAuthAuthorizationRequest, OAuthConfig,
-    OAuthConfig, OAuthTokenExchangeRequest, PermissionMode, PermissionPolicy, ProjectContext, RuntimeError,
+    OAuthTokenExchangeRequest, PermissionMode, PermissionPolicy, ProjectContext, RuntimeError,
     Session, TokenUsage, ToolError, ToolExecutor, UsageTracker,
 };
 use serde_json::json;
@@ -44,6 +46,7 @@ fn max_tokens_for_model(model: &str) -> u32 {
 }
 const DEFAULT_DATE: &str = "2026-03-31";
 const DEFAULT_OAUTH_CALLBACK_PORT: u16 = 4545;
+const TELEMETRY_LOG_PATH_ENV: &str = "CLAW_TELEMETRY_LOG_PATH";
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 const BUILD_TARGET: Option<&str> = option_env!("TARGET");
 const GIT_SHA: Option<&str> = option_env!("GIT_SHA");
@@ -995,6 +998,7 @@ impl LiveCli {
         let session = create_managed_session_handle()?;
         let runtime = build_runtime(
             Session::new(),
+            &session.id,
             model.clone(),
             system_prompt.clone(),
             enable_tools,
@@ -1086,6 +1090,7 @@ impl LiveCli {
         let session = self.runtime.session().clone();
         let mut runtime = build_runtime(
             session,
+            &self.session.id,
             self.model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1232,6 +1237,7 @@ impl LiveCli {
         let message_count = session.messages.len();
         self.runtime = build_runtime(
             session,
+            &self.session.id,
             model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1275,6 +1281,7 @@ impl LiveCli {
         self.permission_mode = permission_mode_from_label(normalized);
         self.runtime = build_runtime(
             session,
+            &self.session.id,
             self.model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1300,6 +1307,7 @@ impl LiveCli {
         self.session = create_managed_session_handle()?;
         self.runtime = build_runtime(
             Session::new(),
+            &self.session.id,
             self.model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1335,6 +1343,7 @@ impl LiveCli {
         let message_count = session.messages.len();
         self.runtime = build_runtime(
             session,
+            &handle.id,
             self.model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1407,6 +1416,7 @@ impl LiveCli {
                 let message_count = session.messages.len();
                 self.runtime = build_runtime(
                     session,
+                    &handle.id,
                     self.model.clone(),
                     self.system_prompt.clone(),
                     true,
@@ -1437,6 +1447,7 @@ impl LiveCli {
         let skipped = removed == 0;
         self.runtime = build_runtime(
             result.compacted_session,
+            &self.session.id,
             self.model.clone(),
             self.system_prompt.clone(),
             true,
@@ -1903,8 +1914,19 @@ fn build_system_prompt() -> Result<Vec<String>, Box<dyn std::error::Error>> {
     )?)
 }
 
+fn build_runtime_feature_config(
+) -> Result<runtime::RuntimeFeatureConfig, Box<dyn std::error::Error>> {
+    let cwd = env::current_dir()?;
+    Ok(ConfigLoader::default_for(cwd)
+        .load()?
+        .feature_config()
+        .clone())
+}
+
+#[allow(clippy::too_many_arguments)]
 fn build_runtime(
     session: Session,
+    session_id: &str,
     model: String,
     system_prompt: Vec<String>,
     enable_tools: bool,
@@ -1913,13 +1935,41 @@ fn build_runtime(
     permission_mode: PermissionMode,
 ) -> Result<ConversationRuntime<AnthropicRuntimeClient, CliToolExecutor>, Box<dyn std::error::Error>>
 {
-    Ok(ConversationRuntime::new(
+    let session_tracer = build_session_tracer(session_id)?;
+    let api_client = match session_tracer.clone() {
+        Some(session_tracer) => {
+            AnthropicRuntimeClient::new(model, enable_tools, emit_output, allowed_tools.clone())?
+                .with_session_tracer(session_tracer)
+        }
+        None => {
+            AnthropicRuntimeClient::new(model, enable_tools, emit_output, allowed_tools.clone())?
+        }
+    };
+    let runtime = ConversationRuntime::new_with_features(
         session,
-        AnthropicRuntimeClient::new(model, enable_tools, emit_output, allowed_tools.clone())?,
+        api_client,
         CliToolExecutor::new(allowed_tools, emit_output),
         permission_policy(permission_mode),
         system_prompt,
-    ))
+        &build_runtime_feature_config()?,
+    );
+    Ok(match session_tracer {
+        Some(session_tracer) => runtime.with_session_tracer(session_tracer),
+        None => runtime,
+    })
+}
+
+fn build_session_tracer(
+    session_id: &str,
+) -> Result<Option<SessionTracer>, Box<dyn std::error::Error>> {
+    let Some(path) = env::var_os(TELEMETRY_LOG_PATH_ENV) else {
+        return Ok(None);
+    };
+    let sink = JsonlTelemetrySink::new(PathBuf::from(path))?;
+    Ok(Some(SessionTracer::new(
+        session_id.to_string(),
+        std::sync::Arc::new(sink),
+    )))
 }
 
 struct CliPermissionPrompter {
@@ -1994,6 +2044,11 @@ impl AnthropicRuntimeClient {
             allowed_tools,
         })
     }
+
+    fn with_session_tracer(mut self, session_tracer: SessionTracer) -> Self {
+        self.client = self.client.with_session_tracer(session_tracer);
+        self
+    }
 }
 
 fn resolve_cli_auth_source() -> Result<AuthSource, Box<dyn std::error::Error>> {
@@ -2099,12 +2154,7 @@ impl ApiClient for AnthropicRuntimeClient {
                         }
                     }
                     ApiStreamEvent::MessageDelta(delta) => {
-                        events.push(AssistantEvent::Usage(TokenUsage {
+                        events.push(AssistantEvent::Usage(delta.usage.token_usage()));
-                            input_tokens: delta.usage.input_tokens,
-                            output_tokens: delta.usage.output_tokens,
-                            cache_creation_input_tokens: 0,
-                            cache_read_input_tokens: 0,
-                        }));
                     }
                     ApiStreamEvent::MessageStop(_) => {
                         saw_stop = true;
@@ -2354,13 +2404,13 @@ fn format_bash_result(icon: &str, parsed: &serde_json::Value) -> String {
         .get("backgroundTaskId")
         .and_then(|value| value.as_str())
     {
-        lines[0].push_str(&format!(" backgrounded ({task_id})"));
+        write!(&mut lines[0], " backgrounded ({task_id})").expect("write to string");
     } else if let Some(status) = parsed
         .get("returnCodeInterpretation")
         .and_then(|value| value.as_str())
         .filter(|status| !status.is_empty())
     {
-        lines[0].push_str(&format!(" {status}"));
+        write!(&mut lines[0], " {status}").expect("write to string");
     }
 
     if let Some(stdout) = parsed.get("stdout").and_then(|value| value.as_str()) {
@@ -2382,15 +2432,15 @@ fn format_read_result(icon: &str, parsed: &serde_json::Value) -> String {
     let path = extract_tool_path(file);
     let start_line = file
         .get("startLine")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(1);
     let num_lines = file
         .get("numLines")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(0);
     let total_lines = file
         .get("totalLines")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(num_lines);
     let content = file
         .get("content")
@@ -2416,8 +2466,7 @@ fn format_write_result(icon: &str, parsed: &serde_json::Value) -> String {
     let line_count = parsed
         .get("content")
         .and_then(|value| value.as_str())
-        .map(|content| content.lines().count())
+        .map_or(0, |content| content.lines().count());
-        .unwrap_or(0);
     format!(
         "{icon} \x1b[1;32m✏️ {} {path}\x1b[0m \x1b[2m({line_count} lines)\x1b[0m",
         if kind == "create" { "Wrote" } else { "Updated" },
@@ -2448,7 +2497,7 @@ fn format_edit_result(icon: &str, parsed: &serde_json::Value) -> String {
     let path = extract_tool_path(parsed);
     let suffix = if parsed
         .get("replaceAll")
-        .and_then(|value| value.as_bool())
+        .and_then(serde_json::Value::as_bool)
         .unwrap_or(false)
     {
         " (replace all)"
@@ -2476,7 +2525,7 @@ fn format_edit_result(icon: &str, parsed: &serde_json::Value) -> String {
 fn format_glob_result(icon: &str, parsed: &serde_json::Value) -> String {
     let num_files = parsed
         .get("numFiles")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(0);
     let filenames = parsed
         .get("filenames")
@@ -2500,11 +2549,11 @@ fn format_glob_result(icon: &str, parsed: &serde_json::Value) -> String {
 fn format_grep_result(icon: &str, parsed: &serde_json::Value) -> String {
     let num_matches = parsed
         .get("numMatches")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(0);
     let num_files = parsed
         .get("numFiles")
-        .and_then(|value| value.as_u64())
+        .and_then(serde_json::Value::as_u64)
         .unwrap_or(0);
     let content = parsed
         .get("content")
@@ -2601,12 +2650,7 @@ fn response_to_events(
         }
     }
 
-    events.push(AssistantEvent::Usage(TokenUsage {
+    events.push(AssistantEvent::Usage(response.usage.token_usage()));
-        input_tokens: response.usage.input_tokens,
-        output_tokens: response.usage.output_tokens,
-        cache_creation_input_tokens: response.usage.cache_creation_input_tokens,
-        cache_read_input_tokens: response.usage.cache_read_input_tokens,
-    }));
     events.push(AssistantEvent::MessageStop);
     Ok(events)
 }

rust/crates/rusty-claude-cli/src/render.rs

@@ -286,7 +286,7 @@ impl TerminalRenderer {
     ) {
         match event {
             Event::Start(Tag::Heading { level, .. }) => {
-                self.start_heading(state, level as u8, output)
+                Self::start_heading(state, level as u8, output);
             }
             Event::End(TagEnd::Paragraph) => output.push_str("\n\n"),
             Event::Start(Tag::BlockQuote(..)) => self.start_quote(state, output),
@@ -426,7 +426,7 @@ impl TerminalRenderer {
         }
     }
 
-    fn start_heading(&self, state: &mut RenderState, level: u8, output: &mut String) {
+    fn start_heading(state: &mut RenderState, level: u8, output: &mut String) {
         state.heading_level = Some(level);
         if !output.is_empty() {
             output.push('\n');

rust/crates/telemetry/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "telemetry"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+publish.workspace = true
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+[lints]
+workspace = true

rust/crates/telemetry/src/lib.rs

@@ -0,0 +1,526 @@
+use std::fmt::{Debug, Formatter};
+use std::fs::{File, OpenOptions};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::{Arc, Mutex};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use serde::{Deserialize, Serialize};
+use serde_json::{Map, Value};
+
+pub const DEFAULT_ANTHROPIC_VERSION: &str = "2023-06-01";
+pub const DEFAULT_APP_NAME: &str = "claude-code";
+pub const DEFAULT_RUNTIME: &str = "rust";
+pub const DEFAULT_AGENTIC_BETA: &str = "claude-code-20250219";
+pub const DEFAULT_PROMPT_CACHING_SCOPE_BETA: &str = "prompt-caching-scope-2026-01-05";
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ClientIdentity {
+    pub app_name: String,
+    pub app_version: String,
+    pub runtime: String,
+}
+
+impl ClientIdentity {
+    #[must_use]
+    pub fn new(app_name: impl Into<String>, app_version: impl Into<String>) -> Self {
+        Self {
+            app_name: app_name.into(),
+            app_version: app_version.into(),
+            runtime: DEFAULT_RUNTIME.to_string(),
+        }
+    }
+
+    #[must_use]
+    pub fn with_runtime(mut self, runtime: impl Into<String>) -> Self {
+        self.runtime = runtime.into();
+        self
+    }
+
+    #[must_use]
+    pub fn user_agent(&self) -> String {
+        format!("{}/{}", self.app_name, self.app_version)
+    }
+}
+
+impl Default for ClientIdentity {
+    fn default() -> Self {
+        Self::new(DEFAULT_APP_NAME, env!("CARGO_PKG_VERSION"))
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct AnthropicRequestProfile {
+    pub anthropic_version: String,
+    pub client_identity: ClientIdentity,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub betas: Vec<String>,
+    #[serde(default, skip_serializing_if = "Map::is_empty")]
+    pub extra_body: Map<String, Value>,
+}
+
+impl AnthropicRequestProfile {
+    #[must_use]
+    pub fn new(client_identity: ClientIdentity) -> Self {
+        Self {
+            anthropic_version: DEFAULT_ANTHROPIC_VERSION.to_string(),
+            client_identity,
+            betas: vec![
+                DEFAULT_AGENTIC_BETA.to_string(),
+                DEFAULT_PROMPT_CACHING_SCOPE_BETA.to_string(),
+            ],
+            extra_body: Map::new(),
+        }
+    }
+
+    #[must_use]
+    pub fn with_beta(mut self, beta: impl Into<String>) -> Self {
+        let beta = beta.into();
+        if !self.betas.contains(&beta) {
+            self.betas.push(beta);
+        }
+        self
+    }
+
+    #[must_use]
+    pub fn with_extra_body(mut self, key: impl Into<String>, value: Value) -> Self {
+        self.extra_body.insert(key.into(), value);
+        self
+    }
+
+    #[must_use]
+    pub fn header_pairs(&self) -> Vec<(String, String)> {
+        let mut headers = vec![
+            (
+                "anthropic-version".to_string(),
+                self.anthropic_version.clone(),
+            ),
+            ("user-agent".to_string(), self.client_identity.user_agent()),
+        ];
+        if !self.betas.is_empty() {
+            headers.push(("anthropic-beta".to_string(), self.betas.join(",")));
+        }
+        headers
+    }
+
+    pub fn render_json_body<T: Serialize>(&self, request: &T) -> Result<Value, serde_json::Error> {
+        let mut body = serde_json::to_value(request)?;
+        let object = body.as_object_mut().ok_or_else(|| {
+            serde_json::Error::io(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                "request body must serialize to a JSON object",
+            ))
+        })?;
+        for (key, value) in &self.extra_body {
+            object.insert(key.clone(), value.clone());
+        }
+        if !self.betas.is_empty() {
+            object.insert(
+                "betas".to_string(),
+                Value::Array(self.betas.iter().cloned().map(Value::String).collect()),
+            );
+        }
+        Ok(body)
+    }
+}
+
+impl Default for AnthropicRequestProfile {
+    fn default() -> Self {
+        Self::new(ClientIdentity::default())
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct AnalyticsEvent {
+    pub namespace: String,
+    pub action: String,
+    #[serde(default, skip_serializing_if = "Map::is_empty")]
+    pub properties: Map<String, Value>,
+}
+
+impl AnalyticsEvent {
+    #[must_use]
+    pub fn new(namespace: impl Into<String>, action: impl Into<String>) -> Self {
+        Self {
+            namespace: namespace.into(),
+            action: action.into(),
+            properties: Map::new(),
+        }
+    }
+
+    #[must_use]
+    pub fn with_property(mut self, key: impl Into<String>, value: Value) -> Self {
+        self.properties.insert(key.into(), value);
+        self
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct SessionTraceRecord {
+    pub session_id: String,
+    pub sequence: u64,
+    pub name: String,
+    pub timestamp_ms: u64,
+    #[serde(default, skip_serializing_if = "Map::is_empty")]
+    pub attributes: Map<String, Value>,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum TelemetryEvent {
+    HttpRequestStarted {
+        session_id: String,
+        attempt: u32,
+        method: String,
+        path: String,
+        #[serde(default, skip_serializing_if = "Map::is_empty")]
+        attributes: Map<String, Value>,
+    },
+    HttpRequestSucceeded {
+        session_id: String,
+        attempt: u32,
+        method: String,
+        path: String,
+        status: u16,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        request_id: Option<String>,
+        #[serde(default, skip_serializing_if = "Map::is_empty")]
+        attributes: Map<String, Value>,
+    },
+    HttpRequestFailed {
+        session_id: String,
+        attempt: u32,
+        method: String,
+        path: String,
+        error: String,
+        retryable: bool,
+        #[serde(default, skip_serializing_if = "Map::is_empty")]
+        attributes: Map<String, Value>,
+    },
+    Analytics(AnalyticsEvent),
+    SessionTrace(SessionTraceRecord),
+}
+
+pub trait TelemetrySink: Send + Sync {
+    fn record(&self, event: TelemetryEvent);
+}
+
+#[derive(Default)]
+pub struct MemoryTelemetrySink {
+    events: Mutex<Vec<TelemetryEvent>>,
+}
+
+impl MemoryTelemetrySink {
+    #[must_use]
+    pub fn events(&self) -> Vec<TelemetryEvent> {
+        self.events
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .clone()
+    }
+}
+
+impl TelemetrySink for MemoryTelemetrySink {
+    fn record(&self, event: TelemetryEvent) {
+        self.events
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .push(event);
+    }
+}
+
+pub struct JsonlTelemetrySink {
+    path: PathBuf,
+    file: Mutex<File>,
+}
+
+impl Debug for JsonlTelemetrySink {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("JsonlTelemetrySink")
+            .field("path", &self.path)
+            .finish_non_exhaustive()
+    }
+}
+
+impl JsonlTelemetrySink {
+    pub fn new(path: impl AsRef<Path>) -> Result<Self, std::io::Error> {
+        let path = path.as_ref().to_path_buf();
+        if let Some(parent) = path.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+        let file = OpenOptions::new().create(true).append(true).open(&path)?;
+        Ok(Self {
+            path,
+            file: Mutex::new(file),
+        })
+    }
+
+    #[must_use]
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+}
+
+impl TelemetrySink for JsonlTelemetrySink {
+    fn record(&self, event: TelemetryEvent) {
+        let Ok(line) = serde_json::to_string(&event) else {
+            return;
+        };
+        let mut file = self
+            .file
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        let _ = writeln!(file, "{line}");
+        let _ = file.flush();
+    }
+}
+
+#[derive(Clone)]
+pub struct SessionTracer {
+    session_id: String,
+    sequence: Arc<AtomicU64>,
+    sink: Arc<dyn TelemetrySink>,
+}
+
+impl Debug for SessionTracer {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("SessionTracer")
+            .field("session_id", &self.session_id)
+            .finish_non_exhaustive()
+    }
+}
+
+impl SessionTracer {
+    #[must_use]
+    pub fn new(session_id: impl Into<String>, sink: Arc<dyn TelemetrySink>) -> Self {
+        Self {
+            session_id: session_id.into(),
+            sequence: Arc::new(AtomicU64::new(0)),
+            sink,
+        }
+    }
+
+    #[must_use]
+    pub fn session_id(&self) -> &str {
+        &self.session_id
+    }
+
+    pub fn record(&self, name: impl Into<String>, attributes: Map<String, Value>) {
+        let record = SessionTraceRecord {
+            session_id: self.session_id.clone(),
+            sequence: self.sequence.fetch_add(1, Ordering::Relaxed),
+            name: name.into(),
+            timestamp_ms: current_timestamp_ms(),
+            attributes,
+        };
+        self.sink.record(TelemetryEvent::SessionTrace(record));
+    }
+
+    pub fn record_http_request_started(
+        &self,
+        attempt: u32,
+        method: impl Into<String>,
+        path: impl Into<String>,
+        attributes: Map<String, Value>,
+    ) {
+        let method = method.into();
+        let path = path.into();
+        self.sink.record(TelemetryEvent::HttpRequestStarted {
+            session_id: self.session_id.clone(),
+            attempt,
+            method: method.clone(),
+            path: path.clone(),
+            attributes: attributes.clone(),
+        });
+        self.record(
+            "http_request_started",
+            merge_trace_fields(method, path, attempt, attributes),
+        );
+    }
+
+    pub fn record_http_request_succeeded(
+        &self,
+        attempt: u32,
+        method: impl Into<String>,
+        path: impl Into<String>,
+        status: u16,
+        request_id: Option<String>,
+        attributes: Map<String, Value>,
+    ) {
+        let method = method.into();
+        let path = path.into();
+        self.sink.record(TelemetryEvent::HttpRequestSucceeded {
+            session_id: self.session_id.clone(),
+            attempt,
+            method: method.clone(),
+            path: path.clone(),
+            status,
+            request_id: request_id.clone(),
+            attributes: attributes.clone(),
+        });
+        let mut trace_attributes = merge_trace_fields(method, path, attempt, attributes);
+        trace_attributes.insert("status".to_string(), Value::from(status));
+        if let Some(request_id) = request_id {
+            trace_attributes.insert("request_id".to_string(), Value::String(request_id));
+        }
+        self.record("http_request_succeeded", trace_attributes);
+    }
+
+    pub fn record_http_request_failed(
+        &self,
+        attempt: u32,
+        method: impl Into<String>,
+        path: impl Into<String>,
+        error: impl Into<String>,
+        retryable: bool,
+        attributes: Map<String, Value>,
+    ) {
+        let method = method.into();
+        let path = path.into();
+        let error = error.into();
+        self.sink.record(TelemetryEvent::HttpRequestFailed {
+            session_id: self.session_id.clone(),
+            attempt,
+            method: method.clone(),
+            path: path.clone(),
+            error: error.clone(),
+            retryable,
+            attributes: attributes.clone(),
+        });
+        let mut trace_attributes = merge_trace_fields(method, path, attempt, attributes);
+        trace_attributes.insert("error".to_string(), Value::String(error));
+        trace_attributes.insert("retryable".to_string(), Value::Bool(retryable));
+        self.record("http_request_failed", trace_attributes);
+    }
+
+    pub fn record_analytics(&self, event: AnalyticsEvent) {
+        let mut attributes = event.properties.clone();
+        attributes.insert(
+            "namespace".to_string(),
+            Value::String(event.namespace.clone()),
+        );
+        attributes.insert("action".to_string(), Value::String(event.action.clone()));
+        self.sink.record(TelemetryEvent::Analytics(event));
+        self.record("analytics", attributes);
+    }
+}
+
+fn merge_trace_fields(
+    method: String,
+    path: String,
+    attempt: u32,
+    mut attributes: Map<String, Value>,
+) -> Map<String, Value> {
+    attributes.insert("method".to_string(), Value::String(method));
+    attributes.insert("path".to_string(), Value::String(path));
+    attributes.insert("attempt".to_string(), Value::from(attempt));
+    attributes
+}
+
+fn current_timestamp_ms() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_millis()
+        .try_into()
+        .unwrap_or(u64::MAX)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn request_profile_emits_headers_and_merges_body() {
+        let profile = AnthropicRequestProfile::new(
+            ClientIdentity::new("claude-code", "1.2.3").with_runtime("rust-cli"),
+        )
+        .with_beta("tools-2026-04-01")
+        .with_extra_body("metadata", serde_json::json!({"source": "test"}));
+
+        assert_eq!(
+            profile.header_pairs(),
+            vec![
+                (
+                    "anthropic-version".to_string(),
+                    DEFAULT_ANTHROPIC_VERSION.to_string()
+                ),
+                ("user-agent".to_string(), "claude-code/1.2.3".to_string()),
+                (
+                    "anthropic-beta".to_string(),
+                    "claude-code-20250219,prompt-caching-scope-2026-01-05,tools-2026-04-01"
+                        .to_string(),
+                ),
+            ]
+        );
+
+        let body = profile
+            .render_json_body(&serde_json::json!({"model": "claude-sonnet"}))
+            .expect("body should serialize");
+        assert_eq!(
+            body["metadata"]["source"],
+            Value::String("test".to_string())
+        );
+        assert_eq!(
+            body["betas"],
+            serde_json::json!([
+                "claude-code-20250219",
+                "prompt-caching-scope-2026-01-05",
+                "tools-2026-04-01"
+            ])
+        );
+    }
+
+    #[test]
+    fn session_tracer_records_structured_events_and_trace_sequence() {
+        let sink = Arc::new(MemoryTelemetrySink::default());
+        let tracer = SessionTracer::new("session-123", sink.clone());
+
+        tracer.record_http_request_started(1, "POST", "/v1/messages", Map::new());
+        tracer.record_analytics(
+            AnalyticsEvent::new("cli", "prompt_sent")
+                .with_property("model", Value::String("claude-opus".to_string())),
+        );
+
+        let events = sink.events();
+        assert!(matches!(
+            &events[0],
+            TelemetryEvent::HttpRequestStarted {
+                session_id,
+                attempt: 1,
+                method,
+                path,
+                ..
+            } if session_id == "session-123" && method == "POST" && path == "/v1/messages"
+        ));
+        assert!(matches!(
+            &events[1],
+            TelemetryEvent::SessionTrace(SessionTraceRecord { sequence: 0, name, .. })
+            if name == "http_request_started"
+        ));
+        assert!(matches!(&events[2], TelemetryEvent::Analytics(_)));
+        assert!(matches!(
+            &events[3],
+            TelemetryEvent::SessionTrace(SessionTraceRecord { sequence: 1, name, .. })
+            if name == "analytics"
+        ));
+    }
+
+    #[test]
+    fn jsonl_sink_persists_events() {
+        let path =
+            std::env::temp_dir().join(format!("telemetry-jsonl-{}.log", current_timestamp_ms()));
+        let sink = JsonlTelemetrySink::new(&path).expect("sink should create file");
+
+        sink.record(TelemetryEvent::Analytics(
+            AnalyticsEvent::new("cli", "turn_completed").with_property("ok", Value::Bool(true)),
+        ));
+
+        let contents = std::fs::read_to_string(&path).expect("telemetry log should be readable");
+        assert!(contents.contains("\"type\":\"analytics\""));
+        assert!(contents.contains("\"action\":\"turn_completed\""));
+
+        let _ = std::fs::remove_file(path);
+    }
+}

rust/crates/tools/src/lib.rs

@@ -13,7 +13,7 @@ use runtime::{
     edit_file, execute_bash, glob_search, grep_search, load_system_prompt, read_file, write_file,
     ApiClient, ApiRequest, AssistantEvent, BashCommandInput, ContentBlock, ConversationMessage,
     ConversationRuntime, GrepSearchInput, MessageRole, PermissionMode, PermissionPolicy,
-    RuntimeError, Session, TokenUsage, ToolError, ToolExecutor,
+    RuntimeError, Session, ToolError, ToolExecutor,
 };
 use serde::{Deserialize, Serialize};
 use serde_json::{json, Value};
@@ -1723,12 +1723,7 @@ impl ApiClient for AnthropicRuntimeClient {
                         }
                     }
                     ApiStreamEvent::MessageDelta(delta) => {
-                        events.push(AssistantEvent::Usage(TokenUsage {
+                        events.push(AssistantEvent::Usage(delta.usage.token_usage()));
-                            input_tokens: delta.usage.input_tokens,
-                            output_tokens: delta.usage.output_tokens,
-                            cache_creation_input_tokens: 0,
-                            cache_read_input_tokens: 0,
-                        }));
                     }
                     ApiStreamEvent::MessageStop(_) => {
                         saw_stop = true;
@@ -1874,12 +1869,7 @@ fn response_to_events(response: MessageResponse) -> Vec<AssistantEvent> {
         }
     }
 
-    events.push(AssistantEvent::Usage(TokenUsage {
+    events.push(AssistantEvent::Usage(response.usage.token_usage()));
-        input_tokens: response.usage.input_tokens,
-        output_tokens: response.usage.output_tokens,
-        cache_creation_input_tokens: response.usage.cache_creation_input_tokens,
-        cache_read_input_tokens: response.usage.cache_read_input_tokens,
-    }));
     events.push(AssistantEvent::MessageStop);
     events
 }