Use native Codex steering and transcript deletion

server/src/session/claude.rs

@@ -47,7 +47,6 @@
 //!   same way as the rest, against 2.1.237 on 2026-08-29.
 
 use std::collections::VecDeque;
-use std::os::unix::fs::OpenOptionsExt;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
@@ -393,9 +392,9 @@ impl ClaudeDriver {
 
         // Fresh logs, because the offsets that index them start at zero and
         // everything the previous process said is already in the transcript.
-        let stdin = make_fifo(&session_dir.join(STDIN_FIFO))?;
-        let stdout = create_log(&session_dir.join(STDOUT_LOG))?;
-        let stderr = create_log(&session_dir.join(STDERR_LOG))?;
+        let stdin = process::make_fifo(&session_dir.join(STDIN_FIFO))?;
+        let stdout = process::create_log(&session_dir.join(STDOUT_LOG))?;
+        let stderr = process::create_log(&session_dir.join(STDERR_LOG))?;
 
         let program = provider.program();
         let launch = Launch::new(program, args, meta.cwd.as_deref());
@@ -1049,44 +1048,6 @@ fn stderr_tail(path: &Path) -> String {
     tail_of(&kept)
 }
 
-/// Creates the stdin fifo if it is not already there, and opens it read-write
-/// for the process to inherit.
-///
-/// Read-write is the whole trick: a fifo opened read-only delivers EOF as soon
-/// as the last writer closes, so the process would exit the moment this server
-/// did -- exactly what leaving it running has to prevent. Holding it open for
-/// writing means the process is its own last writer.
-fn make_fifo(path: &Path) -> Result<std::fs::File> {
-    if !path.exists() {
-        let c_path = std::ffi::CString::new(path.as_os_str().as_encoded_bytes())
-            .with_context(|| format!("{} is not a usable path", path.display()))?;
-        // SAFETY: a nul-terminated path this call only reads, and a mode with
-        // no bits the kernel can object to. Owner-only, like everything else in
-        // a session directory: this carries what the person typed.
-        let made = unsafe { libc::mkfifo(c_path.as_ptr(), 0o600) };
-        if made != 0 {
-            return Err(std::io::Error::last_os_error())
-                .with_context(|| format!("creating the fifo {}", path.display()));
-        }
-    }
-    std::fs::OpenOptions::new()
-        .read(true)
-        .write(true)
-        .open(path)
-        .with_context(|| format!("opening the fifo {}", path.display()))
-}
-
-/// A fresh, empty, owner-only log for one of the process's output streams.
-fn create_log(path: &Path) -> Result<std::fs::File> {
-    std::fs::OpenOptions::new()
-        .create(true)
-        .write(true)
-        .truncate(true)
-        .mode(0o600)
-        .open(path)
-        .with_context(|| format!("creating {}", path.display()))
-}
-
 pub(super) fn read_resume_token(session_dir: &Path) -> Option<String> {
     let text = std::fs::read_to_string(session_dir.join(RESUME_FILE)).ok()?;
     serde_json::from_str::<Value>(&text)