Add addUserText helper; update all call sites

Conversation.addUserMessage now takes a []ContentBlock (symmetric with
addAssistantMessage). Introduce a thin addUserText wrapper in agent.zig
for the plain-text case and update every call site in agent.zig and
anthropic_messages_json.zig accordingly.

1 files changed, 12 insertions, 3 deletions

diff --git a/src/system_prompt.zig b/src/system_prompt.zig
index 6676442..9dce3e5 100644
--- a/src/system_prompt.zig
+++ b/src/system_prompt.zig
@@ -330,6 +330,15 @@ fn projectLayerDir(arena: Allocator, io: Io) ![]u8 {
 
 const testing = std.testing;
 
+/// Test helper: append a single-text user message (the `addUserMessage`
+/// signature now takes a block slice).
+fn addUserText(conv: *panto.Conversation, text: []const u8) !void {
+    const tb = try panto.textualBlockFromSlice(conv.allocator, text);
+    var block: panto.ContentBlock = .{ .Text = tb };
+    errdefer block.deinit(conv.allocator);
+    try conv.addUserMessage(&.{block});
+}
+
 test "blocksEqual - length and content" {
     try testing.expect(blocksEqual(&.{ "a", "b" }, &.{ "a", "b" }));
     try testing.expect(!blocksEqual(&.{ "a", "b" }, &.{ "a", "c" }));
@@ -344,7 +353,7 @@ test "effectiveConfigWindow - no replace anchors to leading system blocks" {
 
     try conv.addSystemMessage("seed");
     try conv.addSystemMessage("append-1");
-    try conv.addUserMessage("hi");
+    try addUserText(&conv, "hi");
 
     var arena_state = std.heap.ArenaAllocator.init(alloc);
     defer arena_state.deinit();
@@ -361,10 +370,10 @@ test "effectiveConfigWindow - anchors to last replace block" {
     defer conv.deinit();
 
     try conv.addSystemMessage("old seed");
-    try conv.addUserMessage("hi");
+    try addUserText(&conv, "hi");
     try conv.replaceSystemMessage("new seed");
     try conv.addSystemMessage("new append");
-    try conv.addUserMessage("again");
+    try addUserText(&conv, "again");
 
     var arena_state = std.heap.ArenaAllocator.init(alloc);
     defer arena_state.deinit();