Add installed voice host lifecycle support (#41902)

## What changed

- Add `VoiceHost` to resolve the packaged voice helper, launch it with an
  allowlisted environment, perform the protocol handshake, and enforce bounded
  shutdown and process cleanup.
- Preserve native executable path encoding in the pipe process APIs.
- Add `third_party/voice/assemble_package.py` to create a fresh package copy
  containing a target-compatible helper and a provenance manifest with file
  hashes.

## Testing

- Cover installed helper lifecycle, build matching, missing and symlinked
  helpers, non-UTF-8 package paths, environment filtering, package validation,
  target pairing, and failure cleanup.

GitOrigin-RevId: f893074b36ae6bb9bcedc00fbe7af6bb72745f4c

codex-rs/voice-host/tests/lifecycle.rs

@@ -1,11 +1,14 @@
 //! Exercise the real helper through installed paths and bounded process I/O.
 
+use std::fs;
 use std::process::Stdio;
 use std::time::Duration;
 
 use anyhow::Context;
 use anyhow::Result;
+use codex_install_context::InstallContext;
 use codex_realtime_webrtc::Message;
+use codex_realtime_webrtc::VoiceHost;
 use codex_realtime_webrtc::decode_frame;
 use codex_realtime_webrtc::encode_frame;
 use codex_utils_cargo_bin::cargo_bin;
@@ -121,3 +124,81 @@ async fn rejects_invalid_input_without_echoing_it() -> Result<()> {
     }
     Ok(())
 }
+#[tokio::test]
+async fn installed_client_rejects_mixed_builds_and_missing_helper() -> Result<()> {
+    let directory = tempfile::Builder::new()
+        .prefix("voice package ")
+        .tempdir()?;
+    let bin = directory.path().join("bin");
+    let helper_dir = directory.path().join("codex-resources/voice/bin");
+    fs::create_dir_all(&bin)?;
+    fs::create_dir_all(&helper_dir)?;
+    fs::write(directory.path().join("codex-package.json"), "{}")?;
+    let app = bin.join(if cfg!(windows) { "codex.exe" } else { "codex" });
+    fs::write(&app, [])?;
+    let source = cargo_bin("codex-voice-host")?;
+    let helper = helper_dir.join(source.file_name().unwrap());
+    fs::copy(&source, &helper)?;
+    let package = InstallContext::from_exe(
+        /*is_macos*/ cfg!(target_os = "macos"),
+        Some(&app),
+        /*method_override*/ None,
+    )
+    .package_layout
+    .unwrap();
+    VoiceHost::connect(&package, &build_commit().await?)
+        .await?
+        .close()
+        .await?;
+    assert!(VoiceHost::connect(&package, "wrong-build").await.is_err());
+    // The same executable elsewhere in the package must not become a fallback.
+    fs::rename(&helper, bin.join(source.file_name().unwrap()))?;
+    assert!(
+        VoiceHost::connect(&package, &build_commit().await?)
+            .await
+            .is_err()
+    );
+    #[cfg(unix)]
+    {
+        std::os::unix::fs::symlink(&source, &helper)?;
+        assert!(
+            VoiceHost::connect(&package, &build_commit().await?)
+                .await
+                .is_err()
+        );
+    }
+    Ok(())
+}
+
+// Linux permits raw-byte filenames; macOS filesystems reject this name themselves.
+#[cfg(target_os = "linux")]
+#[tokio::test]
+async fn installed_client_accepts_non_utf8_package_path() -> Result<()> {
+    use std::ffi::OsString;
+    use std::os::unix::ffi::OsStringExt;
+
+    let directory = tempfile::tempdir()?;
+    let root = directory
+        .path()
+        .join(OsString::from_vec(b"voice-\xff".to_vec()));
+    let bin = root.join("bin");
+    let helper_dir = root.join("codex-resources/voice/bin");
+    fs::create_dir_all(&bin)?;
+    fs::create_dir_all(&helper_dir)?;
+    fs::write(root.join("codex-package.json"), "{}")?;
+    let app = bin.join("codex");
+    fs::write(&app, [])?;
+    let source = cargo_bin("codex-voice-host")?;
+    fs::copy(&source, helper_dir.join(source.file_name().unwrap()))?;
+    let package = InstallContext::from_exe(
+        /*is_macos*/ cfg!(target_os = "macos"),
+        Some(&app),
+        /*method_override*/ None,
+    )
+    .package_layout
+    .context("package layout")?;
+    VoiceHost::connect(&package, &build_commit().await?)
+        .await?
+        .close()
+        .await
+}