From: Anderson A. Giacomolli <agiacomolli@gmail.com>
Date: Fri, 6 Nov 2026 21:53:34 +0000 (-0300)
Subject: Keep a built leaf when the view lags the tree
X-Git-Url: http://git.giacomolli.uk/onechat/commitdiff_plain/c9183f90d757006e7221ecd0d4dc0db2a25f87e0?ds=inline

Keep a built leaf when the view lags the tree

A chat opens again after a crash between the build of a free leaf and
the save of the view. The catch-up adds the messages that the view does
not cover, and it now keeps a leaf that the tree holds already instead
of a second build of it, which the tree refuses as a duplicate. The
parent of such a leaf is settled at the start, with the other built
nodes.

A process that is killed during writes then opens again, so the log
loses no message that it acknowledged.

Issue: 5daf23e
---

diff --git a/memory.go b/memory.go
index cb55cab..c3e9f45 100644
--- a/memory.go
+++ b/memory.go
@@ -272,15 +272,24 @@ func (m *Memory) Append(kind, text string) (Message, error) {
 }
 
 // addMessage builds the leaf of message when it needs no model call, or else
-// adds the leaf to the queue. Then it appends the leaf to the views.
+// adds the leaf to the queue. Then it appends the leaf to the views. A crash can
+// stop an append after the leaf build and before the view save, so a leaf that
+// is built already stays as it is, and restoreQueue settles its parent.
 func (m *Memory) addMessage(message Message) error {
+	built, err := m.tree.Built(0, message.ID)
+	if err != nil {
+		return err
+	}
+
 	leaf, free := freeLeaf(message)
-	if free {
-		err := m.build(leaf)
+	switch {
+	case built:
+	case free:
+		err = m.build(leaf)
 		if err != nil {
 			return err
 		}
-	} else {
+	default:
 		m.queue.AddLeaf(message.ID)
 	}
 
diff --git a/memory_test.go b/memory_test.go
index 8c34149..7b39795 100644
--- a/memory_test.go
+++ b/memory_test.go
@@ -54,6 +54,33 @@ func TestMemoryRestartLoadsTheSameView(t *testing.T) {
 	require.Equal(t, saved, loaded)
 }
 
+func TestMemoryOpensAfterACrashBeforeTheViewSave(t *testing.T) {
+	root := t.TempDir()
+	clock := newTestClock()
+	memory, err := openMemory(t.Context(), root, clock.Now, newFakeSummarizer())
+	require.NoError(t, err)
+
+	_, err = memory.Append("user", "first")
+	require.NoError(t, err)
+
+	saved, err := os.ReadFile(filepath.Join(root, "view.json"))
+	require.NoError(t, err)
+
+	_, err = memory.Append("user", "second")
+	require.NoError(t, err)
+
+	view := memory.View()
+	require.NoError(t, memory.Close())
+
+	// The log and the tree hold message 1, but the view does not.
+	require.NoError(t, os.WriteFile(filepath.Join(root, "view.json"), saved, 0o600))
+
+	memory, err = openMemory(t.Context(), root, clock.Now, newFakeSummarizer())
+	require.NoError(t, err)
+	require.Equal(t, view, memory.View())
+	require.NoError(t, memory.Close())
+}
+
 func TestMemoryKeepsTheCompactionViewCoarser(t *testing.T) {
 	memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now, newFakeSummarizer())
 	require.NoError(t, err)