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, 10 insertions, 0 deletions

diff --git a/libpanto/src/config.zig b/libpanto/src/config.zig
index c48cefc..7c8a495 100644
--- a/libpanto/src/config.zig
+++ b/libpanto/src/config.zig
@@ -27,6 +27,9 @@ pub const APIStyle = enum {
     /// OpenAI Responses API (`/responses`). Used by the ChatGPT-subscription
     /// Codex backend, whose request/stream shape differs from Chat Completions.
     openai_responses,
+    /// ChatGPT-subscription Codex Responses dialect. User config selects this
+    /// with `style = "openai_responses"` plus `dialect = "codex"`.
+    openai_codex_responses,
 };
 
 /// A single HTTP request header (name/value). Used for provider
@@ -155,6 +158,7 @@ pub const ProviderConfig = union(APIStyle) {
     openai_chat: OpenAIChatConfig,
     anthropic_messages: AnthropicMessagesConfig,
     openai_responses: OpenAIResponsesConfig,
+    openai_codex_responses: OpenAIResponsesConfig,
 
     pub fn style(self: ProviderConfig) APIStyle {
         return @as(APIStyle, self);
@@ -187,6 +191,12 @@ pub const ProviderConfig = union(APIStyle) {
                 .model = c.model,
                 .reasoning = c.reasoning,
             },
+            .openai_codex_responses => |c| .{
+                .api_style = .openai_codex_responses,
+                .base_url = c.base_url,
+                .model = c.model,
+                .reasoning = c.reasoning,
+            },
         };
     }
 };