diff --git a/codex-rs/Cargo.toml b/codex-rs/Cargo.toml
index 8ac0361f..e95942cb 100644
--- a/codex-rs/Cargo.toml
+++ b/codex-rs/Cargo.toml
@@ -26,6 +26,7 @@ edition = "2024"
 rust = { }
 
 [workspace.lints.clippy]
+expect_used = "deny"
 unwrap_used = "deny"
 
 [profile.release]
diff --git a/codex-rs/apply-patch/src/lib.rs b/codex-rs/apply-patch/src/lib.rs
index fb8414ec..afabcea4 100644
--- a/codex-rs/apply-patch/src/lib.rs
+++ b/codex-rs/apply-patch/src/lib.rs
@@ -212,7 +212,9 @@ fn extract_heredoc_body_from_apply_patch_command(src: &str) -> anyhow::Result<St
 
     let lang = BASH.into();
     let mut parser = Parser::new();
-    parser.set_language(&lang).expect("load bash grammar");
+    parser
+        .set_language(&lang)
+        .context("failed to load bash grammar")?;
     let tree = parser
         .parse(src, None)
         .ok_or_else(|| anyhow::anyhow!("failed to parse patch into AST"))?;
@@ -225,7 +227,7 @@ fn extract_heredoc_body_from_apply_patch_command(src: &str) -> anyhow::Result<St
         if node.kind() == "heredoc_body" {
             let text = node
                 .utf8_text(bytes)
-                .with_context(|| "failed to interpret heredoc body as UTF-8")?;
+                .context("failed to interpret heredoc body as UTF-8")?;
             return Ok(text.trim_end_matches('\n').to_owned());
         }
 
diff --git a/codex-rs/cli/src/proto.rs b/codex-rs/cli/src/proto.rs
index c1dbce8e..6dbe049c 100644
--- a/codex-rs/cli/src/proto.rs
+++ b/codex-rs/cli/src/proto.rs
@@ -81,8 +81,13 @@ pub async fn run_main(_opts: ProtoCli) -> anyhow::Result<()> {
             };
             match event {
                 Ok(event) => {
-                    let event_str =
-                        serde_json::to_string(&event).expect("JSON serialization failed");
+                    let event_str = match serde_json::to_string(&event) {
+                        Ok(s) => s,
+                        Err(e) => {
+                            error!("Failed to serialize event: {e}");
+                            continue;
+                        }
+                    };
                     println!("{event_str}");
                 }
                 Err(e) => {
diff --git a/codex-rs/core/src/client.rs b/codex-rs/core/src/client.rs
index 6dd20aaa..f8f30391 100644
--- a/codex-rs/core/src/client.rs
+++ b/codex-rs/core/src/client.rs
@@ -28,6 +28,7 @@ use crate::client_common::ResponseEvent;
 use crate::client_common::ResponseStream;
 use crate::client_common::Summary;
 use crate::error::CodexErr;
+use crate::error::EnvVarError;
 use crate::error::Result;
 use crate::flags::CODEX_RS_SSE_FIXTURE;
 use crate::flags::OPENAI_REQUEST_MAX_RETRIES;
@@ -151,10 +152,10 @@ impl ModelClient {
         }
 
         // Assemble tool list: built-in tools + any extra tools from the prompt.
-        let mut tools_json: Vec<serde_json::Value> = DEFAULT_TOOLS
-            .iter()
-            .map(|t| serde_json::to_value(t).expect("serialize builtin tool"))
-            .collect();
+        let mut tools_json = Vec::with_capacity(DEFAULT_TOOLS.len() + prompt.extra_tools.len());
+        for t in DEFAULT_TOOLS.iter() {
+            tools_json.push(serde_json::to_value(t)?);
+        }
         tools_json.extend(
             prompt
                 .extra_tools
@@ -191,10 +192,12 @@ impl ModelClient {
         loop {
             attempt += 1;
 
-            let api_key = self
-                .provider
-                .api_key()?
-                .expect("Repsones API requires an API key");
+            let api_key = self.provider.api_key()?.ok_or_else(|| {
+                CodexErr::EnvVar(EnvVarError {
+                    var: self.provider.env_key.clone().unwrap_or_default(),
+                    instructions: None,
+                })
+            })?;
             let res = self
                 .client
                 .post(&url)
diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index bf08c10f..82296ccb 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -1654,6 +1654,7 @@ fn format_exec_output(output: &str, exit_code: i32, duration: std::time::Duratio
         },
     };
 
+    #[expect(clippy::expect_used)]
     serde_json::to_string(&payload).expect("serialize ExecOutput")
 }
 
diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 2e5b3f19..6a71a45e 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -246,27 +246,30 @@ impl Config {
             })?
             .clone();
 
+        let resolved_cwd = {
+            use std::env;
+
+            match cwd {
+                None => {
+                    tracing::info!("cwd not set, using current dir");
+                    env::current_dir()?
+                }
+                Some(p) if p.is_absolute() => p,
+                Some(p) => {
+                    // Resolve relative path against the current working directory.
+                    tracing::info!("cwd is relative, resolving against current dir");
+                    let mut current = env::current_dir()?;
+                    current.push(p);
+                    current
+                }
+            }
+        };
+
         let config = Self {
             model: model.or(cfg.model).unwrap_or_else(default_model),
             model_provider_id,
             model_provider,
-            cwd: cwd.map_or_else(
-                || {
-                    tracing::info!("cwd not set, using current dir");
-                    std::env::current_dir().expect("cannot determine current dir")
-                },
-                |p| {
-                    if p.is_absolute() {
-                        p
-                    } else {
-                        // Resolve relative paths against the current working directory.
-                        tracing::info!("cwd is relative, resolving against current dir");
-                        let mut cwd = std::env::current_dir().expect("cannot determine cwd");
-                        cwd.push(p);
-                        cwd
-                    }
-                },
-            ),
+            cwd: resolved_cwd,
             approval_policy: approval_policy
                 .or(cfg.approval_policy)
                 .unwrap_or_else(AskForApproval::default),
@@ -292,6 +295,7 @@ impl Config {
     /// Meant to be used exclusively for tests: `load_with_overrides()` should
     /// be used in all other cases.
     pub fn load_default_config_for_test() -> Self {
+        #[expect(clippy::expect_used)]
         Self::load_from_base_config_with_overrides(
             ConfigToml::default(),
             ConfigOverrides::default(),
@@ -371,6 +375,7 @@ pub fn parse_sandbox_permission_with_base_path(
 
 #[cfg(test)]
 mod tests {
+    #![allow(clippy::expect_used, clippy::unwrap_used)]
     use super::*;
 
     /// Verify that the `sandbox_permissions` field on `ConfigToml` correctly
diff --git a/codex-rs/core/src/exec.rs b/codex-rs/core/src/exec.rs
index 35ee96b8..de758c88 100644
--- a/codex-rs/core/src/exec.rs
+++ b/codex-rs/core/src/exec.rs
@@ -344,13 +344,30 @@ pub(crate) async fn consume_truncated_output(
     ctrl_c: Arc<Notify>,
     timeout_ms: Option<u64>,
 ) -> Result<RawExecToolCallOutput> {
+    // Both stdout and stderr were configured with `Stdio::piped()`
+    // above, therefore `take()` should normally return `Some`.  If it doesn't
+    // we treat it as an exceptional I/O error
+
+    let stdout_reader = child.stdout.take().ok_or_else(|| {
+        CodexErr::Io(io::Error::new(
+            io::ErrorKind::Other,
+            "stdout pipe was unexpectedly not available",
+        ))
+    })?;
+    let stderr_reader = child.stderr.take().ok_or_else(|| {
+        CodexErr::Io(io::Error::new(
+            io::ErrorKind::Other,
+            "stderr pipe was unexpectedly not available",
+        ))
+    })?;
+
     let stdout_handle = tokio::spawn(read_capped(
-        BufReader::new(child.stdout.take().expect("stdout is not piped")),
+        BufReader::new(stdout_reader),
         MAX_STREAM_OUTPUT,
         MAX_STREAM_OUTPUT_LINES,
     ));
     let stderr_handle = tokio::spawn(read_capped(
-        BufReader::new(child.stderr.take().expect("stderr is not piped")),
+        BufReader::new(stderr_reader),
         MAX_STREAM_OUTPUT,
         MAX_STREAM_OUTPUT_LINES,
     ));
diff --git a/codex-rs/core/src/exec_linux.rs b/codex-rs/core/src/exec_linux.rs
index 883a46a1..22e97ea4 100644
--- a/codex-rs/core/src/exec_linux.rs
+++ b/codex-rs/core/src/exec_linux.rs
@@ -27,8 +27,7 @@ pub fn exec_linux(
     let tool_call_output = std::thread::spawn(move || {
         let rt = tokio::runtime::Builder::new_current_thread()
             .enable_all()
-            .build()
-            .expect("Failed to create runtime");
+            .build()?;
 
         rt.block_on(async {
             let ExecParams {
diff --git a/codex-rs/core/src/is_safe_command.rs b/codex-rs/core/src/is_safe_command.rs
index 5c688bac..5c5b0d01 100644
--- a/codex-rs/core/src/is_safe_command.rs
+++ b/codex-rs/core/src/is_safe_command.rs
@@ -75,6 +75,7 @@ fn is_safe_to_call_with_exec(command: &[String]) -> bool {
 fn try_parse_bash(bash_lc_arg: &str) -> Option<Tree> {
     let lang = BASH.into();
     let mut parser = Parser::new();
+    #[expect(clippy::expect_used)]
     parser.set_language(&lang).expect("load bash grammar");
 
     let old_tree: Option<&Tree> = None;
diff --git a/codex-rs/core/src/landlock.rs b/codex-rs/core/src/landlock.rs
index e8f5a4de..9a1d2849 100644
--- a/codex-rs/core/src/landlock.rs
+++ b/codex-rs/core/src/landlock.rs
@@ -140,7 +140,7 @@ fn install_network_seccomp_filter_on_current_thread() -> std::result::Result<(),
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::unwrap_used)]
+    #![expect(clippy::unwrap_used, clippy::expect_used)]
 
     use super::*;
     use crate::exec::ExecParams;
diff --git a/codex-rs/core/src/project_doc.rs b/codex-rs/core/src/project_doc.rs
index d468d61d..1ba0dd70 100644
--- a/codex-rs/core/src/project_doc.rs
+++ b/codex-rs/core/src/project_doc.rs
@@ -134,7 +134,7 @@ async fn load_first_candidate(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::unwrap_used)]
+    #![allow(clippy::expect_used, clippy::unwrap_used)]
 
     use super::*;
     use crate::config::Config;
diff --git a/codex-rs/core/tests/live_agent.rs b/codex-rs/core/tests/live_agent.rs
index 5eb275b4..c43c5c19 100644
--- a/codex-rs/core/tests/live_agent.rs
+++ b/codex-rs/core/tests/live_agent.rs
@@ -1,3 +1,5 @@
+#![expect(clippy::unwrap_used, clippy::expect_used)]
+
 //! Live integration tests that exercise the full [`Agent`] stack **against the real
 //! OpenAI `/v1/responses` API**.  These tests complement the lightweight mock‑based
 //! unit tests by verifying that the agent can drive an end‑to‑end conversation,
@@ -65,7 +67,6 @@ async fn spawn_codex() -> Result<Codex, CodexErr> {
 #[ignore]
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn live_streaming_and_prev_id_reset() {
-    #![allow(clippy::unwrap_used)]
     if !api_key_available() {
         eprintln!("skipping live_streaming_and_prev_id_reset – OPENAI_API_KEY not set");
         return;
@@ -140,7 +141,6 @@ async fn live_streaming_and_prev_id_reset() {
 #[ignore]
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn live_shell_function_call() {
-    #![allow(clippy::unwrap_used)]
     if !api_key_available() {
         eprintln!("skipping live_shell_function_call – OPENAI_API_KEY not set");
         return;
diff --git a/codex-rs/core/tests/live_cli.rs b/codex-rs/core/tests/live_cli.rs
index 5561abb8..d79e242c 100644
--- a/codex-rs/core/tests/live_cli.rs
+++ b/codex-rs/core/tests/live_cli.rs
@@ -1,3 +1,5 @@
+#![expect(clippy::expect_used)]
+
 //! Optional smoke tests that hit the real OpenAI /v1/responses endpoint. They are `#[ignore]` by
 //! default so CI stays deterministic and free. Developers can run them locally with
 //! `cargo test --test live_cli -- --ignored` provided they set a valid `OPENAI_API_KEY`.
diff --git a/codex-rs/execpolicy/tests/bad.rs b/codex-rs/execpolicy/tests/bad.rs
index 8b6e195f..5c2999a0 100644
--- a/codex-rs/execpolicy/tests/bad.rs
+++ b/codex-rs/execpolicy/tests/bad.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use codex_execpolicy::NegativeExamplePassedCheck;
 use codex_execpolicy::get_default_policy;
 
diff --git a/codex-rs/execpolicy/tests/cp.rs b/codex-rs/execpolicy/tests/cp.rs
index f34c7fc6..14fd2441 100644
--- a/codex-rs/execpolicy/tests/cp.rs
+++ b/codex-rs/execpolicy/tests/cp.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 extern crate codex_execpolicy;
 
 use codex_execpolicy::ArgMatcher;
diff --git a/codex-rs/execpolicy/tests/good.rs b/codex-rs/execpolicy/tests/good.rs
index 3b7313a3..645728af 100644
--- a/codex-rs/execpolicy/tests/good.rs
+++ b/codex-rs/execpolicy/tests/good.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use codex_execpolicy::PositiveExampleFailedCheck;
 use codex_execpolicy::get_default_policy;
 
diff --git a/codex-rs/execpolicy/tests/head.rs b/codex-rs/execpolicy/tests/head.rs
index d843ac7d..8d7a165c 100644
--- a/codex-rs/execpolicy/tests/head.rs
+++ b/codex-rs/execpolicy/tests/head.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use codex_execpolicy::ArgMatcher;
 use codex_execpolicy::ArgType;
 use codex_execpolicy::Error;
diff --git a/codex-rs/execpolicy/tests/literal.rs b/codex-rs/execpolicy/tests/literal.rs
index d849371e..629aeb9c 100644
--- a/codex-rs/execpolicy/tests/literal.rs
+++ b/codex-rs/execpolicy/tests/literal.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use codex_execpolicy::ArgType;
 use codex_execpolicy::Error;
 use codex_execpolicy::ExecCall;
diff --git a/codex-rs/execpolicy/tests/ls.rs b/codex-rs/execpolicy/tests/ls.rs
index 5c2e47f6..854ec3bf 100644
--- a/codex-rs/execpolicy/tests/ls.rs
+++ b/codex-rs/execpolicy/tests/ls.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 extern crate codex_execpolicy;
 
 use codex_execpolicy::ArgType;
diff --git a/codex-rs/execpolicy/tests/pwd.rs b/codex-rs/execpolicy/tests/pwd.rs
index 0fc46f13..339908e9 100644
--- a/codex-rs/execpolicy/tests/pwd.rs
+++ b/codex-rs/execpolicy/tests/pwd.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 extern crate codex_execpolicy;
 
 use std::vec;
diff --git a/codex-rs/execpolicy/tests/sed.rs b/codex-rs/execpolicy/tests/sed.rs
index dfd7cfd0..064e5393 100644
--- a/codex-rs/execpolicy/tests/sed.rs
+++ b/codex-rs/execpolicy/tests/sed.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 extern crate codex_execpolicy;
 
 use codex_execpolicy::ArgType;
diff --git a/codex-rs/mcp-server/src/codex_tool_config.rs b/codex-rs/mcp-server/src/codex_tool_config.rs
index 89b19f72..78080795 100644
--- a/codex-rs/mcp-server/src/codex_tool_config.rs
+++ b/codex-rs/mcp-server/src/codex_tool_config.rs
@@ -117,6 +117,8 @@ pub(crate) fn create_tool_for_codex_tool_call_param() -> Tool {
         })
         .into_generator()
         .into_root_schema_for::<CodexToolCallParam>();
+
+    #[expect(clippy::expect_used)]
     let schema_value =
         serde_json::to_value(&schema).expect("Codex tool schema should serialise to JSON");
 
@@ -186,6 +188,7 @@ mod tests {
     #[test]
     fn verify_codex_tool_json_schema() {
         let tool = create_tool_for_codex_tool_call_param();
+        #[expect(clippy::expect_used)]
         let tool_json = serde_json::to_value(&tool).expect("tool serializes");
         let expected_tool_json = serde_json::json!({
           "name": "codex",
diff --git a/codex-rs/mcp-server/src/codex_tool_runner.rs b/codex-rs/mcp-server/src/codex_tool_runner.rs
index 4d2b1439..2f8a1a34 100644
--- a/codex-rs/mcp-server/src/codex_tool_runner.rs
+++ b/codex-rs/mcp-server/src/codex_tool_runner.rs
@@ -19,6 +19,7 @@ use tokio::sync::mpsc::Sender;
 
 /// Convert a Codex [`Event`] to an MCP notification.
 fn codex_event_to_notification(event: &Event) -> JSONRPCMessage {
+    #[expect(clippy::expect_used)]
     JSONRPCMessage::Notification(mcp_types::JSONRPCNotification {
         jsonrpc: JSONRPC_VERSION.into(),
         method: "codex/event".into(),
diff --git a/codex-rs/mcp-types/tests/initialize.rs b/codex-rs/mcp-types/tests/initialize.rs
index 69e8b3a6..27902dce 100644
--- a/codex-rs/mcp-types/tests/initialize.rs
+++ b/codex-rs/mcp-types/tests/initialize.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use mcp_types::ClientCapabilities;
 use mcp_types::ClientRequest;
 use mcp_types::Implementation;
diff --git a/codex-rs/mcp-types/tests/progress_notification.rs b/codex-rs/mcp-types/tests/progress_notification.rs
index 396efca2..b518e4a9 100644
--- a/codex-rs/mcp-types/tests/progress_notification.rs
+++ b/codex-rs/mcp-types/tests/progress_notification.rs
@@ -1,3 +1,4 @@
+#![expect(clippy::expect_used)]
 use mcp_types::JSONRPCMessage;
 use mcp_types::ProgressNotificationParams;
 use mcp_types::ProgressToken;