feat: add built-in subquery tool with hierarchical query ids

* Add config options subquery and subquery_max_depth.
* Register an internal subquery function that spawns a fresh LLM query
with the current model configuration but without the full context.
The model selects context numerically (message_indexes) or by text
excerpt (excerpts).
* Subqueries can use tools, including further nested subqueries up to
subquery_max_depth.
* Queries and subqueries get hierarchical ids ([0], [0/1], [0/1/2])
that prefix tool-call prints and spinner messages.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/repl/mod.rs b/src/repl/mod.rs
index f8a51d1..85f4f9c 100644
--- a/src/repl/mod.rs
+++ b/src/repl/mod.rs
@@ -723,6 +723,10 @@ async fn ask(
     mut input: Input,
     with_embeddings: bool,
 ) -> Result<()> {
+    if input.query_path().is_empty() {
+        let root_id = crate::utils::next_query_id(&[]);
+        input.set_query_path(vec![root_id]);
+    }
     if input.is_empty() {
         return Ok(());
     }