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, 9 insertions, 2 deletions

diff --git a/libpanto/src/agent.zig b/libpanto/src/agent.zig
index 1da0261..0ff231a 100644
--- a/libpanto/src/agent.zig
+++ b/libpanto/src/agent.zig
@@ -78,7 +78,12 @@ fn cloneMessage(alloc: Allocator, msg: conversation.Message) !conversation.Messa
     for (msg.content.items) |block| {
         content.appendAssumeCapacity(try cloneBlock(alloc, block));
     }
-    return .{ .role = msg.role, .content = content, .usage = msg.usage };
+    return .{
+        .role = msg.role,
+        .content = content,
+        .usage = msg.usage,
+        .metadata = if (msg.metadata) |m| try alloc.dupe(u8, m) else null,
+    };
 }
 
 fn cloneBlock(alloc: Allocator, block: conversation.ContentBlock) !conversation.ContentBlock {
@@ -91,7 +96,9 @@ fn cloneBlock(alloc: Allocator, block: conversation.ContentBlock) !conversation.
                 mut.deinit(alloc);
             }
             const sig: ?[]const u8 = if (b.signature) |s| try alloc.dupe(u8, s) else null;
-            break :blk .{ .Thinking = .{ .text = tb, .signature = sig } };
+            errdefer if (sig) |s| alloc.free(s);
+            const origin: ?conversation.SignatureOrigin = if (b.signature_origin) |o| try o.dupe(alloc) else null;
+            break :blk .{ .Thinking = .{ .text = tb, .signature = sig, .signature_origin = origin } };
         },
         .ToolUse => |b| blk: {
             const id = try alloc.dupe(u8, b.id);