From 260c7f66fb9578817df5373916474e3c55da9c0c Mon Sep 17 00:00:00 2001
From: Joep Meindertsma <joep@ontola.io>
Date: Sat, 10 Oct 2026 22:38:17 +0000
Subject: [PATCH] Opening a store migrates AI chats without a default agent

Resource::save_as validated the commit for the default agent instead of the
agent that signed it. The AI chat migration in Db::open saves the chat with
the migration's own signer before the server has loaded its agent, so a
node with an old AI chat failed to start with "No agent set".

apply_signed_commit now takes the signing agent. Test: a store with an old
AI chat reopens without an agent and migrates it.
---
 lib/src/db/ai_chat_migration_test.rs | 52 ++++++++++++++++++++++++++++
 lib/src/resources.rs                 |  6 ++--
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/lib/src/db/ai_chat_migration_test.rs b/lib/src/db/ai_chat_migration_test.rs
index 20249fd04..74dc7a39e 100644
--- a/lib/src/db/ai_chat_migration_test.rs
+++ b/lib/src/db/ai_chat_migration_test.rs
@@ -379,3 +379,55 @@ async fn migrating_an_ai_chat_shrinks_the_store() {
     );
     assert!(after < before, "{before} -> {after}");
 }
+
+/// A server opens its store before it loads its agent. Opening a store with an
+/// old AI chat must migrate it without a default agent (node1 crashed on
+/// "No agent set" here).
+#[tokio::test]
+async fn opening_a_store_without_an_agent_migrates_ai_chats() {
+    let w = world("ai_chat_migration_open").await;
+    let chat = old_chat(&w).await;
+    let first = old_ai_message(&w, &chat, "user", "first", 0).await;
+    let second = old_ai_message(&w, &chat, "assistant", "second", 1).await;
+    set_list(&w.db, &chat, MESSAGES, &[first.clone(), second.clone()]).await;
+    // As a store from before: not marked done.
+    w.db.kv.remove(Tree::PluginMeta, AI_DONE_KEY).unwrap();
+    w.db.kv.flush().unwrap();
+    drop(w);
+
+    let path = std::path::Path::new(".temp/db/ai_chat_migration_open");
+    let uploads = std::path::Path::new(".temp/db/ai_chat_migration_open/uploads");
+    let mut reopened = None;
+    let mut last_err = String::new();
+    // The file lock can outlive the drop by a moment.
+    for _ in 0..50 {
+        match Db::init_redb_file(path, Some("https://localhost".into()), uploads).await {
+            Ok(db) => {
+                reopened = Some(db);
+                break;
+            }
+            Err(e) => {
+                last_err = e.to_string();
+                // Only the file lock is worth waiting for.
+                assert!(
+                    !last_err.contains("No agent set"),
+                    "opening needs no agent: {last_err}"
+                );
+                tokio::time::sleep(std::time::Duration::from_millis(200)).await
+            }
+        }
+    }
+    let db = reopened.unwrap_or_else(|| panic!("the store reopens: {last_err}"));
+    assert!(db.get_default_agent().is_err(), "opened without an agent");
+    assert!(!db.ai_chat_migration_pending().unwrap());
+    let found = pages_of(&db, &chat).await;
+    assert_eq!(found.iter().map(|(_, e)| e.len()).sum::<usize>(), 2);
+    assert!(!exists(&db, &first).await);
+    assert!(!exists(&db, &second).await);
+    assert!(db
+        .get_resource(&chat.as_str().into())
+        .await
+        .unwrap()
+        .get(MESSAGES)
+        .is_err());
+}
diff --git a/lib/src/resources.rs b/lib/src/resources.rs
index 5f726d8fa..eff1af42c 100644
--- a/lib/src/resources.rs
+++ b/lib/src/resources.rs
@@ -1312,8 +1312,8 @@ impl Resource {
         &mut self,
         store: &impl Storelike,
         commit: crate::Commit,
+        agent: &crate::agents::Agent,
     ) -> AtomicResult<CommitResponse> {
-        let agent = store.get_default_agent()?;
         let opts = CommitOpts {
             validate_schema: true,
             validate_constraints: true,
@@ -1400,7 +1400,7 @@ impl Resource {
         if should_post {
             crate::client::post_commit(&commit, store).await?;
         }
-        self.apply_signed_commit(store, commit).await
+        self.apply_signed_commit(store, commit, agent).await
     }
 
     /// Saves the resource (with all the changes) to the store by creating a Commit.
@@ -1420,7 +1420,7 @@ impl Resource {
             .clone()
             .sign(&agent, store, self)
             .await?;
-        self.apply_signed_commit(store, commit).await
+        self.apply_signed_commit(store, commit, &agent).await
     }
 
     /// Saves the resource as a new DID-native resource.