Add TelemetryConfig builder methods

Final missing piece in the consumer-facing #[non_exhaustive] config
struct audit. `TelemetryConfig` had public optional fields (otlp_endpoint,
file_path, exporter_type, source_name, capture_content) and an
is_empty() helper, but no `new()` or `with_*` setters — leaving callers
to write `TelemetryConfig { otlp_endpoint: Some(...), ..Default::default() }`
which doesn't compile from outside the crate due to #[non_exhaustive].

Adds `TelemetryConfig::new()` (delegates to Default) and `with_*`
setters for all five fields, matching the existing pattern.
The is_empty() helper stays unchanged.

After this commit, every consumer-facing #[non_exhaustive] struct
in the SDK has a fluent builder: ClientOptions, TelemetryConfig,
Tool, CommandDefinition, CustomAgentConfig, InfiniteSessionConfig,
ProviderConfig, SessionConfig, ResumeSessionConfig,
SystemMessageConfig, MessageOptions, SessionFsConfig, TraceContext.

One unit test (telemetry_config_builder_composes) covering all five
setters + is_empty behavior on a fresh new(). Extends the existing
CHANGELOG "Builder ergonomics" round-out bullet.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: tclem

rust/CHANGELOG.md

@@ -391,9 +391,12 @@ public surface.
   `ProviderConfig::new(base_url)` plus `with_provider_type`,
   `with_wire_api`, `with_api_key`, `with_bearer_token`,
   `with_azure`, `with_headers`; `SystemMessageConfig::new()` plus
-  `with_mode`, `with_content`, `with_sections`. `TraceContext`
-  also gains a symmetric `new()` + `with_traceparent` pair
-  alongside the existing `from_traceparent` shorthand.
+  `with_mode`, `with_content`, `with_sections`;
+  `TelemetryConfig::new()` plus `with_otlp_endpoint`,
+  `with_file_path`, `with_exporter_type`, `with_source_name`,
+  `with_capture_content`. `TraceContext` also gains a symmetric
+  `new()` + `with_traceparent` pair alongside the existing
+  `from_traceparent` shorthand.
 - Documented the direct-field-assignment escape hatch on
   `SessionConfig` and `ResumeSessionConfig` for callers forwarding
   `Option<T>` values from upstream code (matches the

rust/src/lib.rs

@@ -538,6 +538,46 @@ pub struct TelemetryConfig {
 }
 
 impl TelemetryConfig {
+    /// Construct an empty [`TelemetryConfig`]; all fields default to
+    /// unset (`is_empty()` returns `true`).
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Set the OTLP HTTP endpoint URL for trace/metric export.
+    pub fn with_otlp_endpoint(mut self, endpoint: impl Into<String>) -> Self {
+        self.otlp_endpoint = Some(endpoint.into());
+        self
+    }
+
+    /// Set the file path for JSON-lines trace output.
+    pub fn with_file_path(mut self, path: impl Into<PathBuf>) -> Self {
+        self.file_path = Some(path.into());
+        self
+    }
+
+    /// Set the exporter backend type.
+    pub fn with_exporter_type(mut self, exporter_type: OtelExporterType) -> Self {
+        self.exporter_type = Some(exporter_type);
+        self
+    }
+
+    /// Set the instrumentation scope name. Useful for distinguishing
+    /// this embedder's traces from other Copilot-CLI consumers
+    /// exporting to the same backend.
+    pub fn with_source_name(mut self, source_name: impl Into<String>) -> Self {
+        self.source_name = Some(source_name.into());
+        self
+    }
+
+    /// Opt in or out of GenAI message content capture on emitted spans.
+    /// `true` opts in; `false` opts out. Leaving this unset preserves
+    /// the CLI default (typically off).
+    pub fn with_capture_content(mut self, capture: bool) -> Self {
+        self.capture_content = Some(capture);
+        self
+    }
+
     /// Returns `true` if all fields are unset. Used by [`Client::start`]
     /// to decide whether to set `COPILOT_OTEL_ENABLED`.
     pub fn is_empty(&self) -> bool {
@@ -1858,6 +1898,27 @@ mod tests {
             .and_then(|(_, v)| v)
     }
 
+    #[test]
+    fn telemetry_config_builder_composes() {
+        let cfg = TelemetryConfig::new()
+            .with_otlp_endpoint("http://collector:4318")
+            .with_file_path(PathBuf::from("/var/log/copilot.jsonl"))
+            .with_exporter_type(OtelExporterType::OtlpHttp)
+            .with_source_name("my-app")
+            .with_capture_content(true);
+
+        assert_eq!(cfg.otlp_endpoint.as_deref(), Some("http://collector:4318"));
+        assert_eq!(
+            cfg.file_path.as_deref(),
+            Some(Path::new("/var/log/copilot.jsonl")),
+        );
+        assert_eq!(cfg.exporter_type, Some(OtelExporterType::OtlpHttp));
+        assert_eq!(cfg.source_name.as_deref(), Some("my-app"));
+        assert_eq!(cfg.capture_content, Some(true));
+        assert!(!cfg.is_empty());
+        assert!(TelemetryConfig::new().is_empty());
+    }
+
     #[test]
     fn build_command_sets_otel_env_when_telemetry_enabled() {
         let opts = ClientOptions {