diff --git a/codex-rs/core/src/tools/handlers/agent_jobs.rs b/codex-rs/core/src/tools/handlers/agent_jobs.rs
index c9475eeb39..835783e272 100644
--- a/codex-rs/core/src/tools/handlers/agent_jobs.rs
+++ b/codex-rs/core/src/tools/handlers/agent_jobs.rs
@@ -177,6 +177,9 @@ impl JobProgressEmitter {
     }
 }
 
+#[path = "agent_jobs_startup.rs"]
+mod startup;
+
 impl ToolHandler for BatchJobHandler {
     type Output = FunctionToolOutput;
 
@@ -577,6 +580,7 @@ async fn run_agent_job_loop(
         .ok_or_else(|| anyhow::anyhow!("agent job {job_id} was not found"))?;
     let runtime_timeout = job_runtime_timeout(&job);
     let mut active_items: HashMap<ThreadId, ActiveJobItem> = HashMap::new();
+    let mut starting_items = startup::StartupTasks::default();
     let mut progress_emitter = JobProgressEmitter::new();
     recover_running_items(
         session.clone(),
@@ -611,85 +615,55 @@ async fn run_agent_job_loop(
                 .await;
         }
 
-        if !cancel_requested && active_items.len() < options.max_concurrency {
-            let slots = options.max_concurrency - active_items.len();
-            let pending_items = db
-                .list_agent_job_items(
-                    job_id.as_str(),
-                    Some(codex_state::AgentJobItemStatus::Pending),
-                    Some(slots),
-                )
-                .await?;
-            for item in pending_items {
-                let prompt = build_worker_prompt(&job, &item)?;
-                let items = vec![UserInput::Text {
-                    text: prompt,
-                    text_elements: Vec::new(),
-                }];
-                let thread_id = match session
-                    .services
-                    .agent_control
-                    .spawn_agent(
-                        options.spawn_config.clone(),
-                        items.into(),
-                        Some(SessionSource::SubAgent(SubAgentSource::Other(format!(
-                            "agent_job:{job_id}"
-                        )))),
-                    )
-                    .await
-                {
-                    Ok(thread_id) => thread_id,
-                    Err(CodexErr::AgentLimitReached { .. }) => {
-                        db.mark_agent_job_item_pending(
-                            job_id.as_str(),
-                            item.item_id.as_str(),
-                            /*error_message*/ None,
-                        )
-                        .await?;
-                        break;
-                    }
-                    Err(err) => {
-                        let error_message = format!("failed to spawn worker: {err}");
-                        db.mark_agent_job_item_failed(
-                            job_id.as_str(),
-                            item.item_id.as_str(),
-                            error_message.as_str(),
-                        )
-                        .await?;
-                        progressed = true;
-                        continue;
-                    }
-                };
-                let assigned = db
-                    .mark_agent_job_item_running_with_thread(
-                        job_id.as_str(),
-                        item.item_id.as_str(),
-                        thread_id.to_string().as_str(),
-                    )
-                    .await?;
-                if !assigned {
-                    let _ = session
-                        .services
-                        .agent_control
-                        .shutdown_live_agent(thread_id)
-                        .await;
-                    continue;
-                }
-                active_items.insert(
-                    thread_id,
-                    ActiveJobItem {
-                        item_id: item.item_id.clone(),
-                        started_at: Instant::now(),
-                        status_rx: session
-                            .services
-                            .agent_control
-                            .subscribe_status(thread_id)
-                            .await
-                            .ok(),
-                    },
-                );
-                progressed = true;
-            }
+        if startup::drain_ready_startups(
+            session.clone(),
+            db.clone(),
+            job_id.as_str(),
+            &mut active_items,
+            &mut starting_items,
+        )
+        .await?
+        {
+            progressed = true;
+        }
+
+        if !cancel_requested
+            && active_items.len() + starting_items.len() < options.max_concurrency
+            && startup::launch_pending_items(
+                session.clone(),
+                db.clone(),
+                &job,
+                job_id.as_str(),
+                &options,
+                active_items.len(),
+                &mut starting_items,
+            )
+            .await?
+        {
+            progressed = true;
+        }
+
+        if startup::drain_ready_startups(
+            session.clone(),
+            db.clone(),
+            job_id.as_str(),
+            &mut active_items,
+            &mut starting_items,
+        )
+        .await?
+        {
+            progressed = true;
+        }
+
+        if startup::reap_stale_startups(
+            db.clone(),
+            job_id.as_str(),
+            &mut starting_items,
+            runtime_timeout,
+        )
+        .await?
+        {
+            progressed = true;
         }
 
         if reap_stale_active_items(
@@ -708,17 +682,28 @@ async fn run_agent_job_loop(
         if finished.is_empty() {
             let progress = db.get_agent_job_progress(job_id.as_str()).await?;
             if cancel_requested {
-                if progress.running_items == 0 && active_items.is_empty() {
+                if progress.running_items == 0
+                    && active_items.is_empty()
+                    && starting_items.is_empty()
+                {
                     break;
                 }
             } else if progress.pending_items == 0
                 && progress.running_items == 0
                 && active_items.is_empty()
+                && starting_items.is_empty()
             {
                 break;
             }
             if !progressed {
-                wait_for_status_change(&active_items).await;
+                startup::wait_for_startup_or_status_change(
+                    session.clone(),
+                    db.clone(),
+                    job_id.as_str(),
+                    &mut active_items,
+                    &mut starting_items,
+                )
+                .await?;
             }
             continue;
         }
@@ -837,10 +822,10 @@ async fn recover_running_items(
             continue;
         }
         let Some(assigned_thread_id) = item.assigned_thread_id.clone() else {
-            db.mark_agent_job_item_failed(
+            db.mark_agent_job_item_pending(
                 job_id,
                 item.item_id.as_str(),
-                "running item is missing assigned_thread_id",
+                Some("worker startup was interrupted before a thread was assigned"),
             )
             .await?;
             continue;
diff --git a/codex-rs/core/src/tools/handlers/agent_jobs_startup.rs b/codex-rs/core/src/tools/handlers/agent_jobs_startup.rs
new file mode 100644
index 0000000000..83bf3d3636
--- /dev/null
+++ b/codex-rs/core/src/tools/handlers/agent_jobs_startup.rs
@@ -0,0 +1,430 @@
+use super::*;
+use std::collections::HashMap;
+use std::future::Future;
+use tokio::task::AbortHandle;
+use tokio::task::Id as TaskId;
+use tokio::task::JoinError;
+use tokio::task::JoinSet;
+
+#[derive(Debug)]
+pub(super) struct WorkerStartup {
+    pub(super) item_id: String,
+    pub(super) started_at: Instant,
+    pub(super) spawn_latency: Duration,
+    pub(super) result: Result<ThreadId, CodexErr>,
+}
+
+#[derive(Debug)]
+pub(super) struct LaunchingJobItem {
+    item_id: String,
+    started_at: Instant,
+    abort_handle: AbortHandle,
+}
+
+#[derive(Debug, Default)]
+pub(super) struct StartupTasks {
+    starting_items: JoinSet<WorkerStartup>,
+    launching_items: HashMap<TaskId, LaunchingJobItem>,
+}
+
+impl StartupTasks {
+    pub(super) fn len(&self) -> usize {
+        self.starting_items.len()
+    }
+
+    pub(super) fn is_empty(&self) -> bool {
+        self.starting_items.is_empty()
+    }
+}
+
+fn spawn_tracked_startup_task<F>(
+    startup_tasks: &mut StartupTasks,
+    item_id: String,
+    started_at: Instant,
+    task: F,
+) where
+    F: Future<Output = WorkerStartup> + Send + 'static,
+{
+    let abort_handle = startup_tasks.starting_items.spawn(task);
+    startup_tasks.launching_items.insert(
+        abort_handle.id(),
+        LaunchingJobItem {
+            item_id,
+            started_at,
+            abort_handle,
+        },
+    );
+}
+
+pub(super) async fn launch_pending_items(
+    session: Arc<Session>,
+    db: Arc<codex_state::StateRuntime>,
+    job: &codex_state::AgentJob,
+    job_id: &str,
+    options: &JobRunnerOptions,
+    active_items_len: usize,
+    startup_tasks: &mut StartupTasks,
+) -> anyhow::Result<bool> {
+    let slots = options
+        .max_concurrency
+        .saturating_sub(active_items_len + startup_tasks.len());
+    if slots == 0 {
+        return Ok(false);
+    }
+
+    let pending_items = db
+        .list_agent_job_items(
+            job_id,
+            Some(codex_state::AgentJobItemStatus::Pending),
+            Some(slots),
+        )
+        .await?;
+
+    let mut launched = 0usize;
+    let mut progressed = false;
+    for item in pending_items {
+        let claimed = db
+            .mark_agent_job_item_running(job_id, item.item_id.as_str())
+            .await?;
+        if !claimed {
+            continue;
+        }
+
+        let prompt = match build_worker_prompt(job, &item) {
+            Ok(prompt) => prompt,
+            Err(err) => {
+                let error_message = format!("failed to build worker prompt: {err}");
+                db.mark_agent_job_item_failed(
+                    job_id,
+                    item.item_id.as_str(),
+                    error_message.as_str(),
+                )
+                .await?;
+                progressed = true;
+                continue;
+            }
+        };
+
+        let item_id = item.item_id.clone();
+        let session = session.clone();
+        let spawn_config = options.spawn_config.clone();
+        let session_source =
+            SessionSource::SubAgent(SubAgentSource::Other(format!("agent_job:{job_id}")));
+        let started_at = Instant::now();
+        spawn_tracked_startup_task(startup_tasks, item_id.clone(), started_at, async move {
+            let items = vec![UserInput::Text {
+                text: prompt,
+                text_elements: Vec::new(),
+            }];
+            let result = session
+                .services
+                .agent_control
+                .spawn_agent(spawn_config, items.into(), Some(session_source))
+                .await;
+            WorkerStartup {
+                item_id,
+                started_at,
+                spawn_latency: started_at.elapsed(),
+                result,
+            }
+        });
+        launched = launched.saturating_add(1);
+        progressed = true;
+    }
+
+    if launched > 0 {
+        tracing::info!(
+            job_id,
+            launched,
+            active_items = active_items_len,
+            starting_items = startup_tasks.len(),
+            target_concurrency = options.max_concurrency,
+            "agent job queued worker startups"
+        );
+    }
+    Ok(progressed)
+}
+
+pub(super) async fn drain_ready_startups(
+    session: Arc<Session>,
+    db: Arc<codex_state::StateRuntime>,
+    job_id: &str,
+    active_items: &mut HashMap<ThreadId, ActiveJobItem>,
+    startup_tasks: &mut StartupTasks,
+) -> anyhow::Result<bool> {
+    let mut progressed = false;
+    while let Some(result) = startup_tasks.starting_items.try_join_next_with_id() {
+        let starting_items_len = startup_tasks.starting_items.len();
+        handle_worker_startup_result(
+            session.clone(),
+            db.clone(),
+            job_id,
+            active_items,
+            startup_tasks,
+            result,
+            starting_items_len,
+        )
+        .await?;
+        progressed = true;
+    }
+    Ok(progressed)
+}
+
+pub(super) async fn wait_for_startup_or_status_change(
+    session: Arc<Session>,
+    db: Arc<codex_state::StateRuntime>,
+    job_id: &str,
+    active_items: &mut HashMap<ThreadId, ActiveJobItem>,
+    startup_tasks: &mut StartupTasks,
+) -> anyhow::Result<()> {
+    if startup_tasks.is_empty() {
+        wait_for_status_change(active_items).await;
+        return Ok(());
+    }
+
+    let active_items_ref = &*active_items;
+    if active_items_ref.is_empty() {
+        if let Some(result) = startup_tasks.starting_items.join_next_with_id().await {
+            let starting_items_len = startup_tasks.starting_items.len();
+            handle_worker_startup_result(
+                session,
+                db,
+                job_id,
+                active_items,
+                startup_tasks,
+                result,
+                starting_items_len,
+            )
+            .await?;
+        }
+        return Ok(());
+    }
+
+    tokio::select! {
+        startup = startup_tasks.starting_items.join_next_with_id() => {
+            if let Some(result) = startup {
+                let starting_items_len = startup_tasks.starting_items.len();
+                handle_worker_startup_result(
+                    session,
+                    db,
+                    job_id,
+                    active_items,
+                    startup_tasks,
+                    result,
+                    starting_items_len,
+                )
+                .await?;
+            }
+        }
+        _ = wait_for_status_change(active_items_ref) => {}
+    }
+    Ok(())
+}
+
+pub(super) async fn reap_stale_startups(
+    db: Arc<codex_state::StateRuntime>,
+    job_id: &str,
+    startup_tasks: &mut StartupTasks,
+    runtime_timeout: Duration,
+) -> anyhow::Result<bool> {
+    let stale_task_ids: Vec<_> = startup_tasks
+        .launching_items
+        .iter()
+        .filter_map(|(task_id, item)| {
+            (item.started_at.elapsed() >= runtime_timeout).then_some(*task_id)
+        })
+        .collect();
+    if stale_task_ids.is_empty() {
+        return Ok(false);
+    }
+
+    for task_id in stale_task_ids {
+        let Some(item) = startup_tasks.launching_items.remove(&task_id) else {
+            continue;
+        };
+        item.abort_handle.abort();
+        let error_message =
+            format!("worker exceeded max runtime of {runtime_timeout:?} before startup completed");
+        db.mark_agent_job_item_failed(job_id, item.item_id.as_str(), error_message.as_str())
+            .await?;
+        tracing::warn!(
+            job_id,
+            item_id = item.item_id,
+            ?task_id,
+            "agent job worker startup timed out"
+        );
+    }
+    Ok(true)
+}
+
+async fn handle_worker_startup_result(
+    session: Arc<Session>,
+    db: Arc<codex_state::StateRuntime>,
+    job_id: &str,
+    active_items: &mut HashMap<ThreadId, ActiveJobItem>,
+    startup_tasks: &mut StartupTasks,
+    result: Result<(TaskId, WorkerStartup), JoinError>,
+    starting_items_len: usize,
+) -> anyhow::Result<()> {
+    match result {
+        Ok((task_id, startup)) => {
+            startup_tasks.launching_items.remove(&task_id);
+            match startup.result {
+                Ok(thread_id) => {
+                    let thread_id_str = thread_id.to_string();
+                    let assigned = db
+                        .set_agent_job_item_thread(
+                            job_id,
+                            startup.item_id.as_str(),
+                            thread_id_str.as_str(),
+                        )
+                        .await?;
+                    if !assigned {
+                        let _ = session
+                            .services
+                            .agent_control
+                            .shutdown_live_agent(thread_id)
+                            .await;
+                        tracing::debug!(
+                            job_id,
+                            item_id = startup.item_id,
+                            thread_id = %thread_id,
+                            "agent job worker startup finished after item left running state"
+                        );
+                        return Ok(());
+                    }
+
+                    let item_id = startup.item_id;
+                    active_items.insert(
+                        thread_id,
+                        ActiveJobItem {
+                            item_id: item_id.clone(),
+                            started_at: startup.started_at,
+                            status_rx: session
+                                .services
+                                .agent_control
+                                .subscribe_status(thread_id)
+                                .await
+                                .ok(),
+                        },
+                    );
+                    tracing::info!(
+                        job_id,
+                        item_id,
+                        thread_id = %thread_id,
+                        spawn_latency_ms = startup.spawn_latency.as_millis() as u64,
+                        active_items = active_items.len(),
+                        starting_items = starting_items_len,
+                        "agent job worker startup completed"
+                    );
+                }
+                Err(CodexErr::AgentLimitReached { .. }) => {
+                    let _ = db
+                        .mark_agent_job_item_pending(
+                            job_id,
+                            startup.item_id.as_str(),
+                            /*error_message*/ None,
+                        )
+                        .await?;
+                    tracing::debug!(
+                        job_id,
+                        item_id = startup.item_id,
+                        starting_items = starting_items_len,
+                        "agent job worker startup hit agent limit"
+                    );
+                }
+                Err(err) => {
+                    let error_message = format!("failed to spawn worker: {err}");
+                    let _ = db
+                        .mark_agent_job_item_failed(
+                            job_id,
+                            startup.item_id.as_str(),
+                            error_message.as_str(),
+                        )
+                        .await?;
+                    tracing::warn!(
+                        job_id,
+                        item_id = startup.item_id,
+                        error = %err,
+                        "agent job worker startup failed"
+                    );
+                }
+            }
+        }
+        Err(join_error) => {
+            let task_id = join_error.id();
+            let Some(item) = startup_tasks.launching_items.remove(&task_id) else {
+                return Ok(());
+            };
+            let error_message = format!("worker startup task failed: {join_error}");
+            let _ = db
+                .mark_agent_job_item_failed(job_id, item.item_id.as_str(), error_message.as_str())
+                .await?;
+            tracing::warn!(
+                job_id,
+                item_id = item.item_id,
+                error = %join_error,
+                "agent job worker startup task exited unexpectedly"
+            );
+        }
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+    use std::sync::Arc;
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::atomic::Ordering;
+    use tokio::sync::Barrier;
+    use tokio::time::timeout;
+
+    #[tokio::test]
+    async fn spawn_tracked_startup_task_starts_multiple_workers_without_serial_waiting() {
+        let mut startup_tasks = StartupTasks::default();
+        let started = Arc::new(AtomicUsize::new(0));
+        let barrier = Arc::new(Barrier::new(4));
+
+        for idx in 0..3usize {
+            let started = Arc::clone(&started);
+            let barrier = Arc::clone(&barrier);
+            spawn_tracked_startup_task(
+                &mut startup_tasks,
+                format!("item-{idx}"),
+                Instant::now(),
+                async move {
+                    started.fetch_add(1, Ordering::SeqCst);
+                    barrier.wait().await;
+                    WorkerStartup {
+                        item_id: format!("item-{idx}"),
+                        started_at: Instant::now(),
+                        spawn_latency: Duration::ZERO,
+                        result: Err(CodexErr::ThreadNotFound(ThreadId::new())),
+                    }
+                },
+            );
+        }
+
+        timeout(Duration::from_secs(1), async {
+            while started.load(Ordering::SeqCst) < 3 {
+                tokio::task::yield_now().await;
+            }
+        })
+        .await
+        .expect("all startup tasks should begin running");
+
+        assert_eq!(startup_tasks.len(), 3);
+        assert_eq!(startup_tasks.launching_items.len(), 3);
+
+        barrier.wait().await;
+
+        let mut outputs = Vec::new();
+        while let Some(result) = startup_tasks.starting_items.join_next().await {
+            outputs.push(result.expect("startup task should complete").item_id);
+        }
+        outputs.sort();
+        assert_eq!(outputs, vec!["item-0", "item-1", "item-2"]);
+    }
+}
diff --git a/codex-rs/state/src/runtime/agent_jobs.rs b/codex-rs/state/src/runtime/agent_jobs.rs
index 3f5526c58d..bbc7dc4d1e 100644
--- a/codex-rs/state/src/runtime/agent_jobs.rs
+++ b/codex-rs/state/src/runtime/agent_jobs.rs
@@ -319,15 +319,14 @@ WHERE id = ?
         let now = Utc::now().timestamp();
         let result = sqlx::query(
             r#"
-UPDATE agent_job_items
-SET
-    status = ?,
-    assigned_thread_id = NULL,
-    attempt_count = attempt_count + 1,
-    updated_at = ?,
-    last_error = NULL
-WHERE job_id = ? AND item_id = ? AND status = ?
-            "#,
+	UPDATE agent_job_items
+	SET
+	    status = ?,
+	    assigned_thread_id = NULL,
+	    updated_at = ?,
+	    last_error = NULL
+	WHERE job_id = ? AND item_id = ? AND status = ?
+	            "#,
         )
         .bind(AgentJobItemStatus::Running.as_str())
         .bind(now)
@@ -407,10 +406,10 @@ WHERE job_id = ? AND item_id = ? AND status = ?
         let now = Utc::now().timestamp();
         let result = sqlx::query(
             r#"
-UPDATE agent_job_items
-SET assigned_thread_id = ?, updated_at = ?
-WHERE job_id = ? AND item_id = ? AND status = ?
-            "#,
+	UPDATE agent_job_items
+	SET assigned_thread_id = ?, attempt_count = attempt_count + 1, updated_at = ?
+	WHERE job_id = ? AND item_id = ? AND status = ?
+	            "#,
         )
         .bind(thread_id)
         .bind(now)
@@ -681,4 +680,60 @@ mod tests {
         assert_eq!(item.last_error, Some("missing report".to_string()));
         Ok(())
     }
+
+    #[tokio::test]
+    async fn set_agent_job_item_thread_increments_attempt_count_after_claim() -> anyhow::Result<()>
+    {
+        let codex_home = unique_temp_dir();
+        let runtime = StateRuntime::init(codex_home, "test-provider".to_string()).await?;
+        let job_id = "job-1".to_string();
+        let item_id = "item-1".to_string();
+        runtime
+            .create_agent_job(
+                &AgentJobCreateParams {
+                    id: job_id.clone(),
+                    name: "test-job".to_string(),
+                    instruction: "Return a result".to_string(),
+                    auto_export: true,
+                    max_runtime_seconds: None,
+                    output_schema_json: None,
+                    input_headers: vec!["path".to_string()],
+                    input_csv_path: "/tmp/in.csv".to_string(),
+                    output_csv_path: "/tmp/out.csv".to_string(),
+                },
+                &[AgentJobItemCreateParams {
+                    item_id: item_id.clone(),
+                    row_index: 0,
+                    source_id: None,
+                    row_json: json!({"path":"file-1"}),
+                }],
+            )
+            .await?;
+        runtime.mark_agent_job_running(job_id.as_str()).await?;
+
+        let claimed = runtime
+            .mark_agent_job_item_running(job_id.as_str(), item_id.as_str())
+            .await?;
+        assert!(claimed);
+
+        let item = runtime
+            .get_agent_job_item(job_id.as_str(), item_id.as_str())
+            .await?
+            .expect("job item should exist");
+        assert_eq!(item.attempt_count, 0);
+        assert_eq!(item.assigned_thread_id, None);
+
+        let assigned = runtime
+            .set_agent_job_item_thread(job_id.as_str(), item_id.as_str(), "thread-1")
+            .await?;
+        assert!(assigned);
+
+        let item = runtime
+            .get_agent_job_item(job_id.as_str(), item_id.as_str())
+            .await?
+            .expect("job item should exist");
+        assert_eq!(item.attempt_count, 1);
+        assert_eq!(item.assigned_thread_id, Some("thread-1".to_string()));
+        Ok(())
+    }
 }