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, 22 insertions, 0 deletions

diff --git a/src/config/mod.rs b/src/config/mod.rs
index 10718df..693c9f5 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -2,6 +2,7 @@ mod agent;
 mod input;
 mod role;
 mod session;
+mod subquery;
 
 pub use self::agent::{complete_agent_variables, list_agents, Agent, AgentVariables};
 pub use self::input::Input;
@@ -9,6 +10,7 @@ pub use self::role::{
     Role, RoleLike, CODE_ROLE, CREATE_TITLE_ROLE, EXPLAIN_SHELL_ROLE, SHELL_ROLE,
 };
 use self::session::Session;
+pub use self::subquery::{eval_subquery, SubqueryContext};
 
 use crate::client::{
     create_client_config, list_client_types, list_models, ClientConfig, MessageContentToolCalls,
@@ -117,6 +119,9 @@ pub struct Config {
     pub mapping_tools: IndexMap<String, String>,
     pub use_tools: Option<String>,
 
+    pub subquery: bool,
+    pub subquery_max_depth: usize,
+
     pub repl_prelude: Option<String>,
     pub cmd_prelude: Option<String>,
     pub agent_prelude: Option<String>,
@@ -193,6 +198,9 @@ impl Default for Config {
             mapping_tools: Default::default(),
             use_tools: None,
 
+            subquery: false,
+            subquery_max_depth: 3,
+
             repl_prelude: None,
             cmd_prelude: None,
             agent_prelude: None,
@@ -599,6 +607,8 @@ impl Config {
             ("rag_top_k", rag_top_k.to_string()),
             ("dry_run", self.dry_run.to_string()),
             ("function_calling", self.function_calling.to_string()),
+            ("subquery", self.subquery.to_string()),
+            ("subquery_max_depth", self.subquery_max_depth.to_string()),
             ("stream", self.stream.to_string()),
             ("save", self.save.to_string()),
             ("keybindings", self.keybindings.clone()),
@@ -677,6 +687,14 @@ impl Config {
                 }
                 config.write().function_calling = value;
             }
+            "subquery" => {
+                let value = value.parse().with_context(|| "Invalid value")?;
+                config.write().subquery = value;
+            }
+            "subquery_max_depth" => {
+                let value = value.parse().with_context(|| "Invalid value")?;
+                config.write().subquery_max_depth = value;
+            }
             "stream" => {
                 let value = value.parse().with_context(|| "Invalid value")?;
                 config.write().stream = value;
@@ -1710,6 +1728,10 @@ impl Config {
                 );
                 functions = agent_functions;
             }
+
+            if self.subquery {
+                functions.push(self::subquery::subquery_declaration());
+            }
         };
         if functions.is_empty() {
             None