1 files changed, 14 insertions, 2 deletions
diff --git a/libpanto/src/session_manager.zig b/libpanto/src/session_manager.zig
index bf9585d..8b503f2 100644
--- a/libpanto/src/session_manager.zig
+++ b/libpanto/src/session_manager.zig
@@ -37,6 +37,7 @@ pub const SessionEntry = session_mod.SessionEntry;
 pub const MessageEntry = session_mod.MessageEntry;
 pub const DiskMessage = session_mod.DiskMessage;
 pub const DiskMessageRole = session_mod.DiskMessageRole;
+pub const DiskSystemMode = session_mod.DiskSystemMode;
 pub const DiskContentBlock = session_mod.DiskContentBlock;
 pub const Usage = session_mod.Usage;
 pub const CURRENT_VERSION = session_mod.CURRENT_VERSION;
@@ -668,8 +669,19 @@ fn appendMessageToConv(
         content.deinit(allocator);
     }
     try content.ensureTotalCapacity(allocator, disk_msg.content.len);
+    const sys_mode: conversation_mod.SystemMode = switch (disk_msg.mode) {
+        .append => .append,
+        .replace => .replace,
+    };
     for (disk_msg.content) |db| {
-        const block = try session_mod.diskContentBlockToInternal(allocator, db);
+        var block = try session_mod.diskContentBlockToInternal(allocator, db);
+        // System-role text blocks become `.System` blocks carrying the
+        // message's recorded mode, so the append/replace derivation works
+        // on the rebuilt conversation exactly as it did when written.
+        if (disk_msg.role == .system and block == .Text) {
+            const tb = block.Text;
+            block = .{ .System = .{ .text = tb, .mode = sys_mode } };
+        }
         content.appendAssumeCapacity(block);
     }
     const role: conversation_mod.MessageRole = switch (disk_msg.role) {
@@ -1248,7 +1260,7 @@ test "SessionManager: rebuildConversation reconstructs system/user/assistant tur
     defer conv.deinit();
     try testing.expectEqual(@as(usize, 3), conv.messages.items.len);
     try testing.expectEqual(conversation_mod.MessageRole.system, conv.messages.items[0].role);
-    try testing.expectEqualStrings("you are helpful", conv.messages.items[0].content.items[0].Text.items);
+    try testing.expectEqualStrings("you are helpful", conv.messages.items[0].content.items[0].System.text.items);
     try testing.expectEqual(conversation_mod.MessageRole.user, conv.messages.items[1].role);
     try testing.expectEqualStrings("hello", conv.messages.items[1].content.items[0].Text.items);
     try testing.expectEqual(conversation_mod.MessageRole.assistant, conv.messages.items[2].role);