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, 2 insertions, 5 deletions

diff --git a/src/tui_app.zig b/src/tui_app.zig
index 1182777..69eb8fa 100644
--- a/src/tui_app.zig
+++ b/src/tui_app.zig
@@ -1402,16 +1402,13 @@ pub fn runLoop(app: *App, term: *Terminal, opts: RunOptions) !void {
     // that here. Otherwise seed the plain model label.
     if (app.selectors == null) try app.footer.setModel(opts.model_label);
 
-    // Session-start welcome banner as the first transcript entry. cwd is read
-    // from the process; the model label comes from the run options. (Version
-    // is not threaded through the run options yet; the banner omits it.)
+    // Session-start welcome banner as the first transcript entry.
     {
         const welcome = try app.spawnWelcome(.{
             .version = opts.version,
             .cwd = opts.cwd,
             .model = opts.model_label,
         });
-        try welcome.setModel(opts.model_label);
         if (opts.cwd.len != 0) try welcome.setCwd(opts.cwd);
         if (opts.version.len != 0) try welcome.setVersion(opts.version);
     }
@@ -2371,7 +2368,7 @@ test "spawnWelcome shows a session-start banner entry" {
     defer h.teardown(alloc);
 
     const w = try h.app.spawnWelcome(.{});
-    try w.setModel("m");
+    _ = w;
     try testing.expectEqual(@as(usize, 1), h.app.transcript.items.len);
     try testing.expect(h.app.transcript.items[0].kind == .welcome);
 }