fix(codex): display renamed session titles (#4927)

* fix(codex): display renamed session titles

* fix(codex): resolve custom state db for titles

* refactor(codex): dedupe state-db resolution and harden title lookup

- Extract a shared `codex_state_db` module for `state_5.sqlite` path
  resolution (config `sqlite_home` / `CODEX_SQLITE_HOME`), previously
  copy-pasted verbatim between codex_history_migration and the codex
  session provider. `state_5.sqlite` is now a single source of truth.
- Add `busy_timeout` to the read-only title query; without it a read
  during a concurrent Codex write fails immediately (SQLITE_BUSY) and
  renamed titles silently fall back to the first user message.
- Push the `title == first_user_message` comparison into the SQL WHERE
  clause (NULL-safe, aligning with Codex's `distinct_thread_metadata_title`
  semantics) and stop SELECTing `first_user_message`, which can hold
  large values (openai/codex#29007) — the comparison belongs in SQL
  anyway, so the column no longer needs to cross into Rust.

src-tauri/src/codex_state_db.rs

@@ -0,0 +1,98 @@
+//! Locating Codex's per-thread state SQLite databases.
+//!
+//! Codex stores thread metadata in `state_5.sqlite`, normally inside the Codex
+//! config dir (`CODEX_HOME` / `~/.codex`). The SQLite location can be moved with
+//! the `sqlite_home` key in `config.toml` or the `CODEX_SQLITE_HOME` env var;
+//! when set, a second DB lives there. Both history migration and the session
+//! list's title lookup need the same resolution, so it lives here once.
+
+use std::path::{Path, PathBuf};
+
+use toml_edit::DocumentMut;
+
+use crate::config::get_home_dir;
+
+/// Filename of Codex's per-thread state database. Codex bumps the version
+/// number across releases; update this single source of truth when a new state
+/// DB version ships.
+pub(crate) const CODEX_STATE_DB_FILENAME: &str = "state_5.sqlite";
+
+/// Env var that overrides the Codex SQLite state directory.
+const CODEX_SQLITE_HOME_ENV: &str = "CODEX_SQLITE_HOME";
+
+/// Resolve every candidate `state_5.sqlite` path: the config-dir DB plus, when
+/// Codex is configured to keep its SQLite state elsewhere, that DB too.
+///
+/// `config_dir` is the Codex config dir (`~/.codex`); `config_text` is the raw
+/// `config.toml` contents, used to detect a `sqlite_home` override.
+pub(crate) fn codex_state_db_paths(config_dir: &Path, config_text: &str) -> Vec<PathBuf> {
+    let mut paths = Vec::new();
+    push_unique_path(&mut paths, config_dir.join(CODEX_STATE_DB_FILENAME));
+    // Codex lets SQLite state move away from CODEX_HOME; config takes precedence.
+    if let Some(sqlite_home) = sqlite_home_from_codex_config(config_text) {
+        push_unique_path(&mut paths, sqlite_home.join(CODEX_STATE_DB_FILENAME));
+    } else if let Some(sqlite_home) = sqlite_home_from_env() {
+        push_unique_path(&mut paths, sqlite_home.join(CODEX_STATE_DB_FILENAME));
+    }
+    paths
+}
+
+fn push_unique_path(paths: &mut Vec<PathBuf>, path: PathBuf) {
+    if !paths.contains(&path) {
+        paths.push(path);
+    }
+}
+
+fn sqlite_home_from_codex_config(config_text: &str) -> Option<PathBuf> {
+    let doc = config_text.parse::<DocumentMut>().ok()?;
+    let raw = doc.get("sqlite_home")?.as_str()?.trim();
+    if raw.is_empty() {
+        return None;
+    }
+    Some(resolve_user_path(raw))
+}
+
+fn sqlite_home_from_env() -> Option<PathBuf> {
+    let raw = std::env::var(CODEX_SQLITE_HOME_ENV).ok()?;
+    let raw = raw.trim();
+    if raw.is_empty() {
+        return None;
+    }
+    Some(resolve_user_path(raw))
+}
+
+fn resolve_user_path(raw: &str) -> PathBuf {
+    if raw == "~" {
+        return get_home_dir();
+    }
+    if let Some(rest) = raw.strip_prefix("~/") {
+        return get_home_dir().join(rest);
+    }
+    if let Some(rest) = raw.strip_prefix("~\\") {
+        return get_home_dir().join(rest);
+    }
+    PathBuf::from(raw)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn includes_config_sqlite_home() {
+        let temp = tempdir().expect("tempdir");
+        let sqlite_home = temp.path().join("sqlite-home");
+        let config_text = format!("sqlite_home = \"{}\"\n", sqlite_home.display());
+
+        let paths = codex_state_db_paths(temp.path(), &config_text);
+
+        assert_eq!(
+            paths,
+            vec![
+                temp.path().join(CODEX_STATE_DB_FILENAME),
+                sqlite_home.join(CODEX_STATE_DB_FILENAME),
+            ]
+        );
+    }
+}