[codex] Add rollout-backed thread content search (#23519)

## Summary
- add experimental `thread/search` for local rollout-backed thread
search using `rg` over JSONL rollouts
- return search-specific result rows with optional previews instead of
storing preview data on `StoredThread` or ordinary `Thread` responses
- keep `thread/list` separate from full-content search and document the
new app-server surface

## Testing
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-app-server
thread_search_returns_content_and_title_matches -- --nocapture`

codex-rs/app-server-protocol/src/protocol/common.rs

@@ -569,6 +569,12 @@ client_request_definitions! {
         serialization: None,
         response: v2::ThreadListResponse,
     },
+    #[experimental("thread/search")]
+    ThreadSearch => "thread/search" {
+        params: v2::ThreadSearchParams,
+        serialization: None,
+        response: v2::ThreadSearchResponse,
+    },
     ThreadLoadedList => "thread/loaded/list" {
         params: v2::ThreadLoadedListParams,
         serialization: None,

codex-rs/app-server-protocol/src/protocol/v2/thread.rs

@@ -973,6 +973,34 @@ pub struct ThreadListParams {
     pub search_term: Option<String>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadSearchParams {
+    /// Opaque pagination cursor returned by a previous call.
+    #[ts(optional = nullable)]
+    pub cursor: Option<String>,
+    /// Optional page size; defaults to a reasonable server-side value.
+    #[ts(optional = nullable)]
+    pub limit: Option<u32>,
+    /// Optional sort key; defaults to created_at.
+    #[ts(optional = nullable)]
+    pub sort_key: Option<ThreadSortKey>,
+    /// Optional sort direction; defaults to descending (newest first).
+    #[ts(optional = nullable)]
+    pub sort_direction: Option<SortDirection>,
+    /// Optional source filter; when set, only sessions from these source kinds
+    /// are returned. When omitted or empty, defaults to interactive sources.
+    #[ts(optional = nullable)]
+    pub source_kinds: Option<Vec<ThreadSourceKind>>,
+    /// Optional archived filter; when set to true, only archived threads are returned.
+    /// If false or null, only non-archived threads are returned.
+    #[ts(optional = nullable)]
+    pub archived: Option<bool>,
+    /// Required substring/full-text query for thread search.
+    pub search_term: String,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema)]
 #[serde(untagged)]
 pub enum ThreadListCwdFilter {
@@ -1029,6 +1057,29 @@ pub struct ThreadListResponse {
     pub backwards_cursor: Option<String>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadSearchResult {
+    pub thread: Thread,
+    pub snippet: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadSearchResponse {
+    pub data: Vec<ThreadSearchResult>,
+    /// Opaque cursor to pass to the next call to continue after the last item.
+    /// if None, there are no more items to return.
+    pub next_cursor: Option<String>,
+    /// Opaque cursor to pass as `cursor` when reversing `sortDirection`.
+    /// This is only populated when the page contains at least one thread.
+    /// Use it with the opposite `sortDirection`; for timestamp sorts it anchors
+    /// at the start of the page timestamp so same-second updates are not skipped.
+    pub backwards_cursor: Option<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]