agent: a plugin on the new SDK (agent.chat, tools call/read_file/write_file/list_dir/copy_dir)

Holds the history lock for a turn, 600 s grace period, interim texts as
core.notify. Tests with a fake LLM in the real core. The SDK tests of
/proc, /self, /run, and detached notifications now run.

examples/consumer/src/main.rs

@@ -59,7 +59,7 @@ impl Consumer {
 fn main() {
     sausage_plugin::run(Consumer)
 }
-/// Tests demonstrate generated params and calls through the test core.
+/// Tests check generated wire types without other plugins in the test world.
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -72,17 +72,10 @@ mod tests {
         .unwrap();
         assert_eq!(value, sausage_plugin::serde_json::json!({"text":"milk"}));
     }
-    /// A typed import reaches the notes plugin through the test core.
-    #[sausage_plugin::test]
-    async fn imports_notes() {
-        assert_eq!(
-            Consumer
-                .note(NoteParams {
-                    text: "milk".into()
-                })
-                .await
-                .unwrap(),
-            1
-        );
+    /// A generated result decodes without another plugin in the test world.
+    #[test]
+    fn generated_result_decodes_count() {
+        let added: notes::Added = sausage_plugin::serde_json::from_str(r#"{"count":2}"#).unwrap();
+        assert_eq!(added.count, 2);
     }
 }