dynamic tool calls: add param exposeToContext to optionally hide tool (#14501)

This extends dynamic_tool_calls to allow us to hide a tool from the
model context but still use it as part of the general tool calling
runtime (for ex from js_repl/code_mode)

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

@@ -535,13 +535,48 @@ pub struct ToolsV2 {
     pub view_image: Option<bool>,
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[derive(Serialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
 pub struct DynamicToolSpec {
     pub name: String,
     pub description: String,
     pub input_schema: JsonValue,
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub defer_loading: bool,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct DynamicToolSpecDe {
+    name: String,
+    description: String,
+    input_schema: JsonValue,
+    defer_loading: Option<bool>,
+    expose_to_context: Option<bool>,
+}
+
+impl<'de> Deserialize<'de> for DynamicToolSpec {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let DynamicToolSpecDe {
+            name,
+            description,
+            input_schema,
+            defer_loading,
+            expose_to_context,
+        } = DynamicToolSpecDe::deserialize(deserializer)?;
+
+        Ok(Self {
+            name,
+            description,
+            input_schema,
+            defer_loading: defer_loading
+                .unwrap_or_else(|| expose_to_context.map(|visible| !visible).unwrap_or(false)),
+        })
+    }
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS, ExperimentalApi)]
@@ -7655,6 +7690,55 @@ mod tests {
         );
     }
 
+    #[test]
+    fn dynamic_tool_spec_deserializes_defer_loading() {
+        let value = json!({
+            "name": "lookup_ticket",
+            "description": "Fetch a ticket",
+            "inputSchema": {
+                "type": "object",
+                "properties": {
+                    "id": { "type": "string" }
+                }
+            },
+            "deferLoading": true,
+        });
+
+        let actual: DynamicToolSpec = serde_json::from_value(value).expect("deserialize");
+
+        assert_eq!(
+            actual,
+            DynamicToolSpec {
+                name: "lookup_ticket".to_string(),
+                description: "Fetch a ticket".to_string(),
+                input_schema: json!({
+                    "type": "object",
+                    "properties": {
+                        "id": { "type": "string" }
+                    }
+                }),
+                defer_loading: true,
+            }
+        );
+    }
+
+    #[test]
+    fn dynamic_tool_spec_legacy_expose_to_context_inverts_to_defer_loading() {
+        let value = json!({
+            "name": "lookup_ticket",
+            "description": "Fetch a ticket",
+            "inputSchema": {
+                "type": "object",
+                "properties": {}
+            },
+            "exposeToContext": false,
+        });
+
+        let actual: DynamicToolSpec = serde_json::from_value(value).expect("deserialize");
+
+        assert!(actual.defer_loading);
+    }
+
     #[test]
     fn thread_start_params_preserve_explicit_null_service_tier() {
         let params: ThreadStartParams = serde_json::from_value(json!({ "serviceTier": null }))