Mark remaining public config types non_exhaustive

Adds #[non_exhaustive] to the 10 remaining public configuration types
that didn't already carry the attribute:

  - SessionConfig
  - ResumeSessionConfig
  - ClientOptions
  - ProviderConfig
  - McpServerConfig
  - Tool
  - CustomAgentConfig
  - InfiniteSessionConfig
  - SystemMessageConfig
  - ConnectionState

HookEvent, HookOutput, MessageOptions, TelemetryConfig, SessionFsConfig,
FsError, FileInfo, DirEntry, ToolInvocation, Error, Transport, and the
new DeliveryMode were already marked. Closing the asymmetry now means
adding fields to any of these post-1.0 is non-breaking on consumers that
construct via Default::default() plus field assignment or the with_*
builders.

Tradeoff: external crates can no longer use struct-literal syntax for
these types -- not even with ..Default::default(), which only works
inside the defining crate. Tests, examples, and the tool_parameters
doctest are migrated to the let-mut + field-assignment pattern. Callers
porting from 0.1.0-* will see the same compile error and apply the same
mechanical transform.

CHANGELOG entry under Configuration parity.

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

Author: tclem

rust/CHANGELOG.md

@@ -127,6 +127,20 @@ public surface.
   helper signatures are unchanged.
 
 #### Configuration parity
+- All remaining public configuration types are now `#[non_exhaustive]`
+  for forward-compatibility — adding fields post-1.0 is non-breaking on
+  consumers that construct via `Default::default()` plus field
+  assignment or the `with_*` builders. Affected: `SessionConfig`,
+  `ResumeSessionConfig`, `ClientOptions`, `ProviderConfig`,
+  `McpServerConfig`, `Tool`, `CustomAgentConfig`,
+  `InfiniteSessionConfig`, `SystemMessageConfig`, `ConnectionState`.
+  (`HookEvent`, `HookOutput`, `MessageOptions`, `TelemetryConfig`,
+  `SessionFsConfig`, `FsError`, `FileInfo`, `DirEntry`, `ToolInvocation`,
+  `Error`, `Transport`, `DeliveryMode` were already marked.) Callers
+  using exhaustive struct literals must switch to
+  `let mut x = Type::default(); x.field = ...;` or the available `with_*`
+  builders; `..Default::default()` no longer compiles for these types
+  outside the defining crate.
 - `MessageOptions::mode` is now typed `Option<DeliveryMode>` (was
   `Option<String>`). `DeliveryMode` is `#[non_exhaustive]` and serializes
   to the wire strings `"enqueue"` (default) and `"immediate"`. The prior

rust/examples/chat.rs

@@ -90,11 +90,11 @@ fn read_line() -> Option<String> {
 async fn main() -> Result<(), github_copilot_sdk::Error> {
     let client = Client::start(ClientOptions::default()).await?;
 
-    let config = SessionConfig {
-        streaming: Some(true),
-        ..Default::default()
-    }
-    .with_handler(Arc::new(ChatHandler));
+    let config = {
+        let mut cfg = SessionConfig::default();
+        cfg.streaming = Some(true);
+        cfg.with_handler(Arc::new(ChatHandler))
+    };
     let session = client.create_session(config).await?;
 
     println!(

rust/examples/hooks.rs

@@ -101,12 +101,10 @@ impl SessionHooks for AuditHooks {
 async fn main() -> Result<(), github_copilot_sdk::Error> {
     let client = Client::start(ClientOptions::default()).await?;
 
-    let config = SessionConfig {
-        // hooks: true is set automatically when a hooks handler is provided.
-        ..Default::default()
-    }
-    .with_handler(Arc::new(ApproveAllHandler))
-    .with_hooks(Arc::new(AuditHooks));
+    // hooks: true is set automatically when a hooks handler is provided.
+    let config = SessionConfig::default()
+        .with_handler(Arc::new(ApproveAllHandler))
+        .with_hooks(Arc::new(AuditHooks));
     let session = client.create_session(config).await?;
 
     println!(

rust/examples/session_fs.rs

@@ -116,13 +116,14 @@ impl SessionFsProvider for InMemoryProvider {
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let provider: Arc<dyn SessionFsProvider> = Arc::new(InMemoryProvider::new());
 
-    let options = ClientOptions {
-        session_fs: Some(SessionFsConfig::new(
+    let options = {
+        let mut opts = ClientOptions::default();
+        opts.session_fs = Some(SessionFsConfig::new(
             "/workspace",
             "/workspace/.copilot",
             SessionFsConventions::Posix,
-        )),
-        ..Default::default()
+        ));
+        opts
     };
 
     let client = Client::start(options).await?;

rust/examples/tool_server.rs

@@ -60,14 +60,11 @@ struct GetWeatherTool;
 #[async_trait]
 impl ToolHandler for GetWeatherTool {
     fn tool(&self) -> Tool {
-        Tool {
-            name: "get_weather".to_string(),
-            namespaced_name: None,
-            description: "Get the current weather for a city.".to_string(),
-            parameters: tool_parameters(schema_for::<GetWeatherParams>()),
-            instructions: None,
-            ..Default::default()
-        }
+        let mut tool = Tool::default();
+        tool.name = "get_weather".to_string();
+        tool.description = "Get the current weather for a city.".to_string();
+        tool.parameters = tool_parameters(schema_for::<GetWeatherParams>());
+        tool
     }
 
     async fn call(&self, invocation: ToolInvocation) -> Result<ToolResult, Error> {
@@ -94,20 +91,17 @@ struct RollDiceTool;
 #[async_trait]
 impl ToolHandler for RollDiceTool {
     fn tool(&self) -> Tool {
-        Tool {
-            name: "roll_dice".to_string(),
-            namespaced_name: None,
-            description: "Roll one or more dice and return the total.".to_string(),
-            parameters: tool_parameters(serde_json::json!({
-                "type": "object",
-                "properties": {
-                    "sides": { "type": "integer", "description": "Number of sides per die (default 6, max 1000)." },
-                    "count": { "type": "integer", "description": "Number of dice to roll (default 1, max 100)." }
-                }
-            })),
-            instructions: None,
-            ..Default::default()
-        }
+        let mut tool = Tool::default();
+        tool.name = "roll_dice".to_string();
+        tool.description = "Roll one or more dice and return the total.".to_string();
+        tool.parameters = tool_parameters(serde_json::json!({
+            "type": "object",
+            "properties": {
+                "sides": { "type": "integer", "description": "Number of sides per die (default 6, max 1000)." },
+                "count": { "type": "integer", "description": "Number of dice to roll (default 1, max 100)." }
+            }
+        }));
+        tool
     }
 
     async fn call(&self, invocation: ToolInvocation) -> Result<ToolResult, Error> {
@@ -160,11 +154,11 @@ async fn main() -> Result<(), github_copilot_sdk::Error> {
 
     let client = Client::start(ClientOptions::default()).await?;
 
-    let config = SessionConfig {
-        tools: Some(tools),
-        ..Default::default()
-    }
-    .with_handler(handler);
+    let config = {
+        let mut cfg = SessionConfig::default();
+        cfg.tools = Some(tools);
+        cfg.with_handler(handler)
+    };
     let session = client.create_session(config).await?;
 
     println!(

rust/src/lib.rs

@@ -307,6 +307,7 @@ impl From<PathBuf> for CliProgram {
 /// embedded CLI, and then the system PATH and common install locations.
 ///
 /// Set `program` to [`CliProgram::Path`] to use an explicit binary.
+#[non_exhaustive]
 pub struct ClientOptions {
     /// How to locate the CLI binary.
     pub program: CliProgram,

rust/src/tool.rs

@@ -69,14 +69,10 @@ pub fn schema_for<T: schemars::JsonSchema>() -> serde_json::Value {
 /// use github_copilot_sdk::tool::tool_parameters;
 /// use github_copilot_sdk::Tool;
 ///
-/// let tool = Tool {
-///     name: "ping".to_string(),
-///     namespaced_name: None,
-///     description: "ping the server".to_string(),
-///     parameters: tool_parameters(serde_json::json!({"type": "object"})),
-///     instructions: None,
-///     ..Default::default()
-/// };
+/// let mut tool = Tool::default();
+/// tool.name = "ping".to_string();
+/// tool.description = "ping the server".to_string();
+/// tool.parameters = tool_parameters(serde_json::json!({"type": "object"}));
 /// # let _ = tool;
 /// ```
 pub fn tool_parameters(schema: serde_json::Value) -> HashMap<String, serde_json::Value> {

rust/src/types.rs

@@ -31,6 +31,7 @@ use crate::transforms::SystemMessageTransform;
 /// unexpectedly.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
+#[non_exhaustive]
 pub enum ConnectionState {
     /// No CLI process is attached or the process has exited cleanly.
     Disconnected,
@@ -303,6 +304,7 @@ impl PartialEq<&str> for RequestId {
 /// in the wire schema but are honored by the CLI.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct Tool {
     /// Tool identifier (e.g., `"bash"`, `"grep"`, `"str_replace_editor"`).
     pub name: String,
@@ -436,6 +438,7 @@ impl Serialize for CommandDefinition {
 /// when the session starts.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct CustomAgentConfig {
     /// Unique name of the custom agent.
     pub name: String,
@@ -483,6 +486,7 @@ pub struct DefaultAgentConfig {
 /// directory.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct InfiniteSessionConfig {
     /// Whether infinite sessions are enabled. Defaults to `true` on the CLI.
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -534,6 +538,7 @@ pub struct InfiniteSessionConfig {
 /// ```
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(tag = "type", rename_all = "lowercase")]
+#[non_exhaustive]
 pub enum McpServerConfig {
     /// Local MCP server launched as a subprocess and addressed over stdio.
     /// On the wire this serializes as `{"type": "stdio", ...}`. The CLI
@@ -601,6 +606,7 @@ pub struct McpHttpServerConfig {
 /// Copilot's default routing.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct ProviderConfig {
     /// Provider type: `"openai"`, `"azure"`, or `"anthropic"`. Defaults to
     /// `"openai"` on the CLI.
@@ -650,6 +656,7 @@ pub struct AzureProviderOptions {
 /// `availableTools`, `systemMessage`, etc.
 #[derive(Clone, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct SessionConfig {
     /// Custom session ID. When unset, the CLI generates one.
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -998,6 +1005,7 @@ impl SessionConfig {
 /// See [`SessionConfig`] for the note on snake_case vs. camelCase field naming.
 #[derive(Clone, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct ResumeSessionConfig {
     /// ID of the session to resume.
     pub session_id: SessionId,
@@ -1272,6 +1280,7 @@ impl ResumeSessionConfig {
 /// section-level overrides.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct SystemMessageConfig {
     /// How content is applied: `"append"` (default), `"replace"`, or `"customize"`.
     #[serde(skip_serializing_if = "Option::is_none")]

rust/tests/integration_test.rs

@@ -6,10 +6,9 @@ use github_copilot_sdk::resolve::copilot_binary_with_source;
 use github_copilot_sdk::{Client, ClientOptions, SDK_PROTOCOL_VERSION};
 
 fn default_options() -> ClientOptions {
-    ClientOptions {
-        cwd: std::env::current_dir().expect("cwd"),
-        ..Default::default()
-    }
+    let mut opts = ClientOptions::default();
+    opts.cwd = std::env::current_dir().expect("cwd");
+    opts
 }
 
 #[tokio::test]

rust/tests/session_test.rs

@@ -249,13 +249,11 @@ async fn create_session_sends_correct_rpc() {
         let client = client.clone();
         async move {
             client
-                .create_session(
-                    SessionConfig {
-                        model: Some("gpt-4".to_string()),
-                        ..Default::default()
-                    }
-                    .with_handler(Arc::new(NoopHandler)),
-                )
+                .create_session({
+                    let mut cfg = SessionConfig::default();
+                    cfg.model = Some("gpt-4".to_string());
+                    cfg.with_handler(Arc::new(NoopHandler))
+                })
                 .await
                 .unwrap()
         }
@@ -1870,13 +1868,7 @@ async fn request_elicitation_sent_in_create_params() {
         let client = client.clone();
         async move {
             client
-                .create_session(
-                    SessionConfig {
-                        request_elicitation: Some(true),
-                        ..Default::default()
-                    }
-                    .with_handler(Arc::new(NoopHandler)),
-                )
+                .create_session(SessionConfig::default().with_handler(Arc::new(NoopHandler)))
                 .await
                 .unwrap()
         }
@@ -2413,13 +2405,14 @@ fn session_config_serializes_bucket_b_fields() {
 
     use github_copilot_sdk::{SessionConfig, SessionId};
 
-    let cfg = SessionConfig {
-        session_id: Some(SessionId::from("custom-id")),
-        config_dir: Some(PathBuf::from("/tmp/cfg")),
-        working_directory: Some(PathBuf::from("/tmp/work")),
-        github_token: Some("ghs_secret".to_string()),
-        include_sub_agent_streaming_events: Some(false),
-        ..SessionConfig::default()
+    let cfg = {
+        let mut cfg = SessionConfig::default();
+        cfg.session_id = Some(SessionId::from("custom-id"));
+        cfg.config_dir = Some(PathBuf::from("/tmp/cfg"));
+        cfg.working_directory = Some(PathBuf::from("/tmp/work"));
+        cfg.github_token = Some("ghs_secret".to_string());
+        cfg.include_sub_agent_streaming_events = Some(false);
+        cfg
     };
     let json = serde_json::to_value(&cfg).unwrap();
     assert_eq!(json["sessionId"], "custom-id");
@@ -2967,9 +2960,10 @@ async fn validate_session_fs_config_rejects_empty_initial_cwd() {
         "/state",
         SessionFsConventions::Posix,
     );
-    let opts = github_copilot_sdk::ClientOptions {
-        session_fs: Some(cfg),
-        ..Default::default()
+    let opts = {
+        let mut opts = github_copilot_sdk::ClientOptions::default();
+        opts.session_fs = Some(cfg);
+        opts
     };
     let err = github_copilot_sdk::Client::start(opts).await.err();
     let err_string = format!("{err:?}");