memoryd: ask_memory, each workspace's chat at once with its own limit

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/memoryd/tests/support/honcho.rs

@@ -2,8 +2,8 @@
 //! responses recorded from rift (`tests/fixtures/honcho/`), by method and path (a batch of
 //! messages or conclusions answered with as many as it asked for, up to the two recorded), and
 //! records every request, body included. It can be set to answer every request with a status
-//! instead, to answer nothing, or to answer as a workspace that does not exist, for every
-//! workspace or for one. Stopped, and its held connections released, when dropped; every wait has
+//! instead, to answer nothing, to answer as a workspace that does not exist, or to answer a chat
+//! with a given text, for every workspace or for one. Stopped, and its held connections released, when dropped; every wait has
 //! a deadline. Do not edit.
 
 #![allow(dead_code)] // each test file uses a different part of this module
@@ -50,6 +50,8 @@ pub enum Mode {
     /// As a workspace that does not exist: a search or a conclusion query answers 200 with no
     /// hits (fixtures 34, 35), chat 404 (36).
     Missing,
+    /// A chat answers 200 with this text as its `content`; anything else as `Fixtures`.
+    Chat(&'static str),
 }
 
 struct Shared {
@@ -238,6 +240,8 @@ fn answer(request: &Request, made: &Mutex<HashSet<String>>) -> (u16, String) {
             request,
             "conclusions",
         ),
+        // A workspace chat answers the recorded one at `minimal` (fixture 19), whatever it asked.
+        ("POST", ["v3", "workspaces", _, "chat"]) => fixture("19-workspace-chat.json"),
         // A search answers the three recorded messages about tea (fixture 30), whatever it asked.
         ("POST", ["v3", "workspaces", _, "search"]) => fixture("30-workspace-search-limit.json"),
         // A conclusion query answers the recorded one about the owner (32) when it asks about
@@ -296,6 +300,11 @@ fn serve(mut stream: TcpStream, shared: &Shared) {
             fixture("35-conclusions-query-missing-workspace.json")
         }
         Mode::Missing => fixture("36-workspace-chat-missing-workspace.json"),
+        Mode::Chat(content) if request.path.ends_with("/chat") => (
+            200,
+            serde_json::json!({ "content": content, "evidence": null }).to_string(),
+        ),
+        Mode::Chat(_) => answer(&request, &shared.made),
         Mode::Status(422) => {
             let input = request.body.clone().unwrap_or(Value::Null);
             (