Use generic search metadata for dynamic tools (#27356)

## Why

Dynamic tools maintained a separate search-text builder even though the
shared tool search path already derives the same metadata from
`ToolSpec`. Using the shared path removes duplicate behavior before
adding explicit namespaces.

## What changed

- Build dynamic-tool search entries with
`ToolSearchInfo::from_tool_spec`.
- Remove the custom search-text state and its implementation-only unit
test.

The old search text included the tool name, its space-separated form,
description, namespace, and top-level parameter names. The shared
builder preserves all of those terms and also indexes namespace
descriptions and nested schema metadata.

## Test plan

- `just test -p codex-core
tool_search_returns_deferred_dynamic_tool_and_routes_follow_up_call`

codex-rs/core/src/tools/handlers/dynamic.rs

@@ -33,7 +33,6 @@ pub struct DynamicToolHandler {
     tool_name: ToolName,
     spec: ToolSpec,
     exposure: ToolExposure,
-    search_text: String,
 }
 
 impl DynamicToolHandler {
@@ -56,7 +55,6 @@ impl DynamicToolHandler {
             } else {
                 ToolExposure::Direct
             },
-            search_text: build_dynamic_search_text(tool),
         })
     }
 }
@@ -75,8 +73,7 @@ impl ToolExecutor<ToolInvocation> for DynamicToolHandler {
     }
 
     fn search_info(&self) -> Option<ToolSearchInfo> {
-        ToolSearchInfo::from_spec(
-            self.search_text.clone(),
+        ToolSearchInfo::from_tool_spec(
             self.spec(),
             Some(ToolSearchSourceInfo {
                 name: "Dynamic tools".to_string(),
@@ -217,27 +214,3 @@ async fn request_dynamic_tool(
 
     response
 }
-
-fn build_dynamic_search_text(tool: &DynamicToolSpec) -> String {
-    let mut schema_properties = tool
-        .input_schema
-        .get("properties")
-        .and_then(serde_json::Value::as_object)
-        .map(|map| map.keys().cloned().collect::<Vec<_>>())
-        .unwrap_or_default();
-    schema_properties.sort();
-    let mut parts = vec![
-        tool.name.clone(),
-        tool.name.replace('_', " "),
-        tool.description.clone(),
-    ];
-    if let Some(namespace) = &tool.namespace {
-        parts.push(namespace.clone());
-    }
-    parts.extend(schema_properties);
-    parts.join(" ")
-}
-
-#[cfg(test)]
-#[path = "dynamic_tests.rs"]
-mod tests;

codex-rs/core/src/tools/handlers/dynamic_tests.rs

@@ -1,36 +0,0 @@
-use super::*;
-use codex_tools::ToolSearchSourceInfo;
-use pretty_assertions::assert_eq;
-use serde_json::json;
-
-#[test]
-fn search_info_uses_dynamic_tool_metadata_and_parameter_names() {
-    let handler = DynamicToolHandler::new(&DynamicToolSpec {
-        namespace: Some("codex_app".to_string()),
-        name: "automation_update".to_string(),
-        description: "Create or update automations.".to_string(),
-        input_schema: json!({
-            "type": "object",
-            "properties": {
-                "timezone": { "type": "string" },
-                "mode": { "type": "string" }
-            }
-        }),
-        defer_loading: true,
-    })
-    .expect("dynamic handler should be created");
-
-    let search_info = handler.search_info().expect("dynamic search info");
-
-    assert_eq!(
-        search_info.entry.search_text,
-        "automation_update automation update Create or update automations. codex_app mode timezone"
-    );
-    assert_eq!(
-        search_info.source_info,
-        Some(ToolSearchSourceInfo {
-            name: "Dynamic tools".to_string(),
-            description: Some("Tools provided by the current Codex thread.".to_string()),
-        })
-    );
-}