Add Codex Responses support and session debugging

Teach provider config and auth resolution about the Codex Responses
dialect, including user-facing `style = "openai_responses"` with
`dialect = "codex"`. Serialize and parse Responses traffic with
provider-specific reasoning replay, assistant phase metadata, and robust
function-call assembly keyed by `output_index` so streamed tool inputs
survive proxy quirks and empty terminal payloads.

Also persist thinking origins and message metadata across sessions, add
the Anthropic interleaved-thinking header switch, write per-session
debug logs, and improve the TUI and scripts for inspecting tool output
and session costs.

1 files changed, 58 insertions, 1 deletions

diff --git a/libpanto/src/file_system_jsonl_store.zig b/libpanto/src/file_system_jsonl_store.zig
index 1d56ae9..e47698c 100644
--- a/libpanto/src/file_system_jsonl_store.zig
+++ b/libpanto/src/file_system_jsonl_store.zig
@@ -709,7 +709,7 @@ pub const SessionFile = struct {
 
         for (self.entries.items) |entry| {
             switch (entry) {
-                .message => |me| try appendMessageToConv(&conv, self.allocator, me.message),
+                .message => |me| try appendMessageToConv(&conv, self.allocator, me.message, me.stamp),
             }
         }
         return conv;
@@ -733,6 +733,7 @@ fn appendMessageToConv(
     conv: *conversation_mod.Conversation,
     allocator: Allocator,
     disk_msg: StoredMessage,
+    stamp: ?session_mod.WireStamp,
 ) !void {
     var content: std.ArrayList(conversation_mod.ContentBlock) = .empty;
     errdefer {
@@ -756,6 +757,14 @@ fn appendMessageToConv(
             const tb = block.Text;
             block = .{ .System = .{ .text = tb, .mode = sys_mode } };
         }
+        if (block == .Thinking and stamp != null) {
+            block.Thinking.signature_origin = try conversation_mod.SignatureOrigin.init(
+                allocator,
+                stamp.?.api_style,
+                stamp.?.base_url,
+                stamp.?.model,
+            );
+        }
         content.appendAssumeCapacity(block);
     }
     const role: conversation_mod.MessageRole = switch (disk_msg.role) {
@@ -2090,3 +2099,51 @@ test "FileSystemJSONLStore catalog: create → append → load round-trips" {
     try testing.expectEqual(@as(usize, 2), loaded.messages.items.len);
     try testing.expectEqual(conversation_mod.MessageRole.user, loaded.messages.items[0].role);
 }
+
+test "FileSystemJSONLStore load restores thinking signature origin from message stamp" {
+    const io = testing.io;
+
+    var td = try TmpSessionDir.init(testing.allocator);
+    defer td.deinit(testing.allocator);
+    const sessions = try std.fs.path.join(testing.allocator, &.{ td.abs_path, "sessions" });
+    defer testing.allocator.free(sessions);
+
+    var catalog = try FileSystemJSONLStore.init(testing.allocator, io, sessions);
+    defer catalog.deinit();
+    const store = catalog.store();
+
+    var sess = store.create();
+    defer sess.info.deinit(testing.allocator);
+
+    var conv = conversation_mod.Conversation.init(testing.allocator);
+    defer conv.deinit();
+    try addUserText(&conv, "ping");
+    try conv.addAssistantMessage(&.{
+        .{ .Thinking = .{
+            .text = try conversation_mod.textualBlockFromSlice(testing.allocator, "thinking..."),
+            .signature = try testing.allocator.dupe(u8, "sig123"),
+        } },
+        .{ .Text = try conversation_mod.textualBlockFromSlice(testing.allocator, "pong") },
+    }, null);
+
+    const id: session_store_mod.WireIdentity = .{
+        .api_style = .anthropic_messages,
+        .base_url = "https://api.anthropic.com",
+        .model = "claude-sonnet-4-20250514",
+    };
+    var batch = [_]session_store_mod.PersistentMessage{
+        .{ .message = conv.messages.items[0], .identity = id },
+        .{ .message = conv.messages.items[1], .identity = id },
+    };
+    try sess.append(&batch);
+
+    var loaded = (try store.load(sess.info.id)).?;
+    defer loaded.deinit();
+    const thinking = loaded.messages.items[1].content.items[0].Thinking;
+    try testing.expect(thinking.signature_origin != null);
+    try testing.expect(thinking.signature_origin.?.matches(
+        .anthropic_messages,
+        "https://api.anthropic.com",
+        "claude-sonnet-4-20250514",
+    ));
+}