enable-resume (#3537)

Adding the ability to resume conversations.
we have one verb `resume`. 

Behavior:

`tui`:
`codex resume`: opens session picker
`codex resume --last`: continue last message
`codex resume <session id>`: continue conversation with `session id`

`exec`:
`codex resume --last`: continue last conversation
`codex resume <session id>`: continue conversation with `session id`

Implementation:
- I added a function to find the path in `~/.codex/sessions/` with a
`UUID`. This is helpful in resuming with session id.
- Added the above mentioned flags
- Added lots of testing

codex-rs/core/src/rollout/list.rs

@@ -3,6 +3,10 @@ use std::io::{self};
 use std::path::Path;
 use std::path::PathBuf;
 
+use codex_file_search as file_search;
+use std::num::NonZero;
+use std::sync::Arc;
+use std::sync::atomic::AtomicBool;
 use time::OffsetDateTime;
 use time::PrimitiveDateTime;
 use time::format_description::FormatItem;
@@ -334,3 +338,48 @@ async fn read_head_and_flags(
 
     Ok((head, saw_session_meta, saw_user_event))
 }
+
+/// Locate a recorded conversation rollout file by its UUID string using the existing
+/// paginated listing implementation. Returns `Ok(Some(path))` if found, `Ok(None)` if not present
+/// or the id is invalid.
+pub async fn find_conversation_path_by_id_str(
+    codex_home: &Path,
+    id_str: &str,
+) -> io::Result<Option<PathBuf>> {
+    // Validate UUID format early.
+    if Uuid::parse_str(id_str).is_err() {
+        return Ok(None);
+    }
+
+    let mut root = codex_home.to_path_buf();
+    root.push(SESSIONS_SUBDIR);
+    if !root.exists() {
+        return Ok(None);
+    }
+    // This is safe because we know the values are valid.
+    #[allow(clippy::unwrap_used)]
+    let limit = NonZero::new(1).unwrap();
+    // This is safe because we know the values are valid.
+    #[allow(clippy::unwrap_used)]
+    let threads = NonZero::new(2).unwrap();
+    let cancel = Arc::new(AtomicBool::new(false));
+    let exclude: Vec<String> = Vec::new();
+    let compute_indices = false;
+
+    let results = file_search::run(
+        id_str,
+        limit,
+        &root,
+        exclude,
+        threads,
+        cancel,
+        compute_indices,
+    )
+    .map_err(|e| io::Error::other(format!("file search failed: {e}")))?;
+
+    Ok(results
+        .matches
+        .into_iter()
+        .next()
+        .map(|m| root.join(m.path)))
+}

codex-rs/core/src/rollout/mod.rs

@@ -8,6 +8,7 @@ pub(crate) mod policy;
 pub mod recorder;
 
 pub use codex_protocol::protocol::SessionMeta;
+pub use list::find_conversation_path_by_id_str;
 pub use recorder::RolloutRecorder;
 pub use recorder::RolloutRecorderParams;
 

codex-rs/core/src/rollout/recorder.rs

@@ -204,7 +204,6 @@ impl RolloutRecorder {
 
     pub(crate) async fn get_rollout_history(path: &Path) -> std::io::Result<InitialHistory> {
         info!("Resuming rollout from {path:?}");
-        tracing::error!("Resuming rollout from {path:?}");
         let text = tokio::fs::read_to_string(path).await?;
         if text.trim().is_empty() {
             return Err(IoError::other("empty session file"));
@@ -254,7 +253,7 @@ impl RolloutRecorder {
             }
         }
 
-        tracing::error!(
+        info!(
             "Resumed rollout with {} items, conversation ID: {:?}",
             items.len(),
             conversation_id