fix(runtime): skip non-UTF-8 environment variables instead of panicking (#3356)

std::env::vars() panics on any non-UTF-8 value. zsh exports a metafied
$_ when the command path contains non-ASCII characters (e.g. 下載), so
claw panicked on startup. Use vars_os() and skip entries that are not
valid UTF-8.

rust/crates/runtime/src/remote.rs

@@ -66,7 +66,7 @@ pub struct UpstreamProxyState {
 impl RemoteSessionContext {
     #[must_use]
     pub fn from_env() -> Self {
-        Self::from_env_map(&env::vars().collect())
+        Self::from_env_map(&utf8_env_map())
     }
 
     #[must_use]
@@ -89,7 +89,7 @@ impl RemoteSessionContext {
 impl UpstreamProxyBootstrap {
     #[must_use]
     pub fn from_env() -> Self {
-        Self::from_env_map(&env::vars().collect())
+        Self::from_env_map(&utf8_env_map())
     }
 
     #[must_use]
@@ -234,6 +234,16 @@ pub fn inherited_upstream_proxy_env(
         .collect()
 }
 
+/// Snapshot of the process environment, skipping non-UTF-8 entries.
+///
+/// `env::vars()` panics on non-UTF-8 values (e.g. zsh exports a metafied `$_`
+/// when the command path contains non-ASCII characters).
+fn utf8_env_map() -> BTreeMap<String, String> {
+    env::vars_os()
+        .filter_map(|(key, value)| Some((key.into_string().ok()?, value.into_string().ok()?)))
+        .collect()
+}
+
 fn default_ca_bundle_path() -> PathBuf {
     env::var_os("HOME")
         .map_or_else(|| PathBuf::from("."), PathBuf::from)

rust/crates/runtime/src/sandbox.rs

@@ -109,7 +109,11 @@ impl SandboxConfig {
 pub fn detect_container_environment() -> ContainerEnvironment {
     let proc_1_cgroup = fs::read_to_string("/proc/1/cgroup").ok();
     detect_container_environment_from(SandboxDetectionInputs {
-        env_pairs: env::vars().collect(),
+        // `env::vars()` panics on non-UTF-8 values (e.g. zsh exports a
+        // metafied `$_` for non-ASCII paths); skip those entries instead.
+        env_pairs: env::vars_os()
+            .filter_map(|(key, value)| Some((key.into_string().ok()?, value.into_string().ok()?)))
+            .collect(),
         dockerenv_exists: Path::new("/.dockerenv").exists(),
         containerenv_exists: Path::new("/run/.containerenv").exists(),
         proc_1_cgroup: proc_1_cgroup.as_deref(),

rust/crates/rusty-claude-cli/tests/cli_flags_and_config_defaults.rs

@@ -257,6 +257,34 @@ fn local_smoke_commands_do_not_require_live_credentials() {
     fs::remove_dir_all(temp_dir).expect("cleanup temp dir");
 }
 
+#[cfg(unix)]
+#[test]
+fn doctor_tolerates_non_utf8_environment_values() {
+    use std::ffi::OsStr;
+    use std::os::unix::ffi::OsStrExt;
+
+    // given: zsh exports a metafied (non-UTF-8) `$_` when the command path
+    // contains non-ASCII characters such as `下載`
+    let temp_dir = unique_temp_dir("non-utf8-env");
+    let config_home = temp_dir.join(".claw");
+    fs::create_dir_all(&config_home).expect("config home should exist");
+    let metafied_path = OsStr::from_bytes(b"/home/user/\xe4\xb8\x83\xab\xe8\xbc\x83\xa9/claw");
+
+    // when
+    let output = offline_command_in(&temp_dir, &config_home)
+        .env("_", metafied_path)
+        .arg("doctor")
+        .output()
+        .expect("claw should launch");
+
+    // then
+    assert_success(&output);
+    let stdout = String::from_utf8(output.stdout).expect("stdout should be utf8");
+    assert!(stdout.contains("Doctor"));
+
+    fs::remove_dir_all(temp_dir).expect("cleanup temp dir");
+}
+
 #[test]
 fn local_subcommand_help_does_not_fall_through_to_runtime_or_provider_calls() {
     let temp_dir = unique_temp_dir("subcommand-help");