From c36e821610feb7a692efd4dc075a17d2a9b02b7f Mon Sep 17 00:00:00 2001
From: Albin Cassirer <cassirer@openai.com>
Date: Tue, 21 Apr 2026 12:01:18 -0700
Subject: [PATCH] Add debug trace reduction command

---
 codex-rs/Cargo.lock      |  1 +
 codex-rs/cli/Cargo.toml  |  1 +
 codex-rs/cli/src/main.rs | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 3f26f563f8..225d7f692a 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -2116,6 +2116,7 @@ dependencies = [
  "codex-protocol",
  "codex-responses-api-proxy",
  "codex-rmcp-client",
+ "codex-rollout-trace",
  "codex-sandboxing",
  "codex-state",
  "codex-stdio-to-uds",
diff --git a/codex-rs/cli/Cargo.toml b/codex-rs/cli/Cargo.toml
index d318297f8f..2a9c5a6ff7 100644
--- a/codex-rs/cli/Cargo.toml
+++ b/codex-rs/cli/Cargo.toml
@@ -43,6 +43,7 @@ codex-model-provider = { workspace = true }
 codex-protocol = { workspace = true }
 codex-responses-api-proxy = { workspace = true }
 codex-rmcp-client = { workspace = true }
+codex-rollout-trace = { workspace = true }
 codex-sandboxing = { workspace = true }
 codex-state = { workspace = true }
 codex-stdio-to-uds = { workspace = true }
diff --git a/codex-rs/cli/src/main.rs b/codex-rs/cli/src/main.rs
index 3dee811fac..f378afad2c 100644
--- a/codex-rs/cli/src/main.rs
+++ b/codex-rs/cli/src/main.rs
@@ -22,6 +22,8 @@ use codex_exec::Command as ExecCommand;
 use codex_exec::ReviewArgs;
 use codex_execpolicy::ExecPolicyCheckCommand;
 use codex_responses_api_proxy::Args as ResponsesApiProxyArgs;
+use codex_rollout_trace::REDUCED_STATE_FILE_NAME;
+use codex_rollout_trace::replay_bundle;
 use codex_state::StateRuntime;
 use codex_state::state_db_path;
 use codex_tui::AppExitInfo;
@@ -216,6 +218,10 @@ enum DebugSubcommand {
     /// Render the model-visible prompt input list as JSON.
     PromptInput(DebugPromptInputCommand),
 
+    /// Replay a rollout trace bundle and write reduced state JSON.
+    #[clap(hide = true)]
+    TraceReduce(DebugTraceReduceCommand),
+
     /// Internal: reset local memory state for a fresh start.
     #[clap(hide = true)]
     ClearMemories,
@@ -257,6 +263,17 @@ struct DebugModelsCommand {
     bundled: bool,
 }
 
+#[derive(Debug, Parser)]
+struct DebugTraceReduceCommand {
+    /// Trace bundle directory containing manifest.json and trace.jsonl.
+    #[arg(value_name = "TRACE_BUNDLE")]
+    trace_bundle: PathBuf,
+
+    /// Output path for reduced RolloutTrace JSON. Defaults to TRACE_BUNDLE/state.json.
+    #[arg(long = "output", short = 'o', value_name = "FILE")]
+    output: Option<PathBuf>,
+}
+
 #[derive(Debug, Parser)]
 struct ResumeCommand {
     /// Conversation/session id (UUID) or thread name. UUIDs take precedence if it parses.
@@ -1065,6 +1082,14 @@ async fn cli_main(arg0_paths: Arg0DispatchPaths) -> anyhow::Result<()> {
                 )
                 .await?;
             }
+            DebugSubcommand::TraceReduce(cmd) => {
+                reject_remote_mode_for_subcommand(
+                    root_remote.as_deref(),
+                    root_remote_auth_token_env.as_deref(),
+                    "debug trace-reduce",
+                )?;
+                run_debug_trace_reduce_command(cmd).await?;
+            }
             DebugSubcommand::ClearMemories => {
                 reject_remote_mode_for_subcommand(
                     root_remote.as_deref(),
@@ -1265,6 +1290,19 @@ fn maybe_print_under_development_feature_warning(
     );
 }
 
+async fn run_debug_trace_reduce_command(cmd: DebugTraceReduceCommand) -> anyhow::Result<()> {
+    let output = cmd
+        .output
+        .unwrap_or_else(|| cmd.trace_bundle.join(REDUCED_STATE_FILE_NAME));
+
+    let trace = replay_bundle(&cmd.trace_bundle)?;
+    let reduced_json = serde_json::to_vec_pretty(&trace)?;
+    tokio::fs::write(&output, reduced_json).await?;
+    println!("{}", output.display());
+
+    Ok(())
+}
+
 async fn run_debug_prompt_input_command(
     cmd: DebugPromptInputCommand,
     root_config_overrides: CliConfigOverrides,