diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 371968d6d096..0c689b10a3e7 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -1961,6 +1961,7 @@ dependencies = [
  "tracing",
  "tungstenite",
  "url",
+ "uuid",
  "wiremock",
 ]
 
diff --git a/codex-rs/codex-api/Cargo.toml b/codex-rs/codex-api/Cargo.toml
index 21f6b674250c..21d51fb15a4b 100644
--- a/codex-rs/codex-api/Cargo.toml
+++ b/codex-rs/codex-api/Cargo.toml
@@ -29,6 +29,7 @@ eventsource-stream = { workspace = true }
 regex-lite = { workspace = true }
 tokio-util = { workspace = true, features = ["codec", "io"] }
 url = { workspace = true }
+uuid = { workspace = true }
 
 [dev-dependencies]
 anyhow = { workspace = true }
diff --git a/codex-rs/codex-api/src/files.rs b/codex-rs/codex-api/src/files.rs
index c56855588537..8f3ceacedba9 100644
--- a/codex-rs/codex-api/src/files.rs
+++ b/codex-rs/codex-api/src/files.rs
@@ -11,6 +11,7 @@ use reqwest::StatusCode;
 use reqwest::header::CONTENT_LENGTH;
 use serde::Deserialize;
 use tokio::time::Instant;
+use uuid::Uuid;
 
 pub const OPENAI_FILE_URI_PREFIX: &str = "sediment://";
 pub const OPENAI_FILE_UPLOAD_LIMIT_BYTES: u64 = 512 * 1024 * 1024;
@@ -46,6 +47,27 @@ pub enum OpenAiFileError {
         #[source]
         source: reqwest::Error,
     },
+    #[error(
+        "OpenAI file blob upload to {host} failed after {elapsed_ms} ms ({error_kind}, azure_client_request_id={azure_client_request_id}): {source}"
+    )]
+    BlobUploadRequest {
+        host: String,
+        elapsed_ms: u128,
+        error_kind: &'static str,
+        azure_client_request_id: String,
+        #[source]
+        source: reqwest::Error,
+    },
+    #[error(
+        "OpenAI file blob upload to {host} failed with status {status} (azure_client_request_id={azure_client_request_id}, azure_request_id={azure_request_id}, azure_error_code={azure_error_code})"
+    )]
+    BlobUploadStatus {
+        host: String,
+        status: StatusCode,
+        azure_client_request_id: String,
+        azure_request_id: String,
+        azure_error_code: String,
+    },
     #[error("OpenAI file request to {url} failed with status {status}: {body}")]
     UnexpectedStatus {
         url: String,
@@ -139,25 +161,80 @@ pub async fn upload_openai_file(
             source,
         })?;
 
+    let upload_host = url::Url::parse(&create_payload.upload_url)
+        .ok()
+        .and_then(|url| url.host_str().map(str::to_owned))
+        .unwrap_or_else(|| "unknown-host".to_string());
+    let azure_client_request_id = Uuid::new_v4().to_string();
+    let upload_started_at = Instant::now();
     let upload_response = build_reqwest_client(http_client_factory, &create_payload.upload_url)?
         .put(&create_payload.upload_url)
         .timeout(OPENAI_FILE_REQUEST_TIMEOUT)
         .header("x-ms-blob-type", "BlockBlob")
+        .header("x-ms-client-request-id", &azure_client_request_id)
         .header(CONTENT_LENGTH, file_size_bytes)
         .body(reqwest::Body::wrap_stream(contents))
         .send()
         .await
-        .map_err(|source| OpenAiFileError::Request {
-            url: create_payload.upload_url.clone(),
-            source,
+        .map_err(|source| {
+            let elapsed_ms = upload_started_at.elapsed().as_millis();
+            let error_kind = if source.is_timeout() {
+                "timeout"
+            } else if source.is_connect() {
+                "connect"
+            } else if source.is_body() {
+                "body"
+            } else if source.is_request() {
+                "request"
+            } else {
+                "other"
+            };
+            tracing::event!(
+                target: "codex_otel.log_only",
+                tracing::Level::WARN,
+                event.name = "codex.openai_file_blob_upload_failed",
+                file_id = %create_payload.file_id,
+                host = %upload_host,
+                file_size_bytes,
+                elapsed_ms,
+                error_kind,
+                azure_client_request_id,
+                "OpenAI file blob upload transport failed"
+            );
+            OpenAiFileError::BlobUploadRequest {
+                host: upload_host.clone(),
+                elapsed_ms,
+                error_kind,
+                azure_client_request_id: azure_client_request_id.clone(),
+                source: source.without_url(),
+            }
         })?;
     let upload_status = upload_response.status();
-    let upload_body = upload_response.text().await.unwrap_or_default();
+    let cloudflare_ray_id = upload_response_header(&upload_response, "cf-ray");
+    let azure_request_id = upload_response_header(&upload_response, "x-ms-request-id");
+    let azure_error_code = upload_response_header(&upload_response, "x-ms-error-code");
     if !upload_status.is_success() {
-        return Err(OpenAiFileError::UnexpectedStatus {
-            url: create_payload.upload_url.clone(),
+        tracing::event!(
+            target: "codex_otel.log_only",
+            tracing::Level::WARN,
+            event.name = "codex.openai_file_blob_upload_failed",
+            file_id = %create_payload.file_id,
+            host = %upload_host,
+            file_size_bytes,
+            elapsed_ms = upload_started_at.elapsed().as_millis(),
+            status = %upload_status,
+            cloudflare_ray_id,
+            azure_client_request_id,
+            azure_request_id,
+            azure_error_code,
+            "OpenAI file blob upload failed"
+        );
+        return Err(OpenAiFileError::BlobUploadStatus {
+            host: upload_host,
             status: upload_status,
-            body: upload_body,
+            azure_client_request_id,
+            azure_request_id,
+            azure_error_code,
         });
     }
 
@@ -274,6 +351,15 @@ fn build_reqwest_client(
     }
 }
 
+fn upload_response_header(response: &reqwest::Response, header: &str) -> String {
+    response
+        .headers()
+        .get(header)
+        .and_then(|value| value.to_str().ok())
+        .unwrap_or("missing")
+        .to_string()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -288,6 +374,7 @@ mod tests {
     use wiremock::ResponseTemplate;
     use wiremock::matchers::body_json;
     use wiremock::matchers::header;
+    use wiremock::matchers::header_regex;
     use wiremock::matchers::method;
     use wiremock::matchers::path;
 
@@ -336,6 +423,7 @@ mod tests {
         Mock::given(method("PUT"))
             .and(path("/upload/file_123"))
             .and(header("content-length", "5"))
+            .and(header_regex("x-ms-client-request-id", "^[0-9a-f-]{36}$"))
             .respond_with(ResponseTemplate::new(200))
             .mount(&server)
             .await;
@@ -386,4 +474,81 @@ mod tests {
         assert_eq!(uploaded.mime_type, Some("text/plain".to_string()));
         assert_eq!(finalize_attempts.load(Ordering::SeqCst), 2);
     }
+
+    #[tokio::test]
+    async fn upload_openai_file_reports_blob_response_diagnostics_without_sas() {
+        let server = MockServer::start().await;
+        Mock::given(method("POST"))
+            .and(path("/backend-api/files"))
+            .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
+                "file_id": "file_123",
+                "upload_url": format!("{}/upload/file_123?sig=secret", server.uri()),
+            })))
+            .mount(&server)
+            .await;
+        Mock::given(method("PUT"))
+            .and(path("/upload/file_123"))
+            .respond_with(
+                ResponseTemplate::new(500)
+                    .insert_header("x-ms-request-id", "azure-request")
+                    .insert_header("x-ms-error-code", "ServerBusy")
+                    .set_body_string("try again"),
+            )
+            .mount(&server)
+            .await;
+
+        let error = upload_openai_file(
+            &base_url_for(&server),
+            &chatgpt_auth(),
+            &default_http_client_factory(),
+            "hello.txt".to_string(),
+            /*file_size_bytes*/ 5,
+            futures::stream::iter([Ok::<_, std::io::Error>(Bytes::from_static(b"hello"))]),
+        )
+        .await
+        .expect_err("blob response failure should be returned");
+
+        let message = error.to_string();
+        assert!(message.contains("failed with status 500"));
+        assert!(message.contains("azure_client_request_id="));
+        assert!(message.contains("azure_request_id=azure-request"));
+        assert!(message.contains("azure_error_code=ServerBusy"));
+        assert!(!message.contains("try again"));
+        assert!(!message.contains("sig=secret"));
+    }
+
+    #[tokio::test]
+    async fn upload_openai_file_reports_blob_transport_diagnostics_without_sas() {
+        let upload_listener = tokio::net::TcpListener::bind("127.0.0.1:0")
+            .await
+            .expect("bind upload address");
+        let upload_address = upload_listener.local_addr().expect("upload address");
+        drop(upload_listener);
+        let server = MockServer::start().await;
+        Mock::given(method("POST"))
+            .and(path("/backend-api/files"))
+            .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
+                "file_id": "file_123",
+                "upload_url": format!("http://{upload_address}/upload?sig=secret"),
+            })))
+            .mount(&server)
+            .await;
+
+        let error = upload_openai_file(
+            &base_url_for(&server),
+            &chatgpt_auth(),
+            &default_http_client_factory(),
+            "hello.txt".to_string(),
+            /*file_size_bytes*/ 5,
+            futures::stream::iter([Ok::<_, std::io::Error>(Bytes::from_static(b"hello"))]),
+        )
+        .await
+        .expect_err("blob transport failure should be returned");
+
+        let message = error.to_string();
+        assert!(message.contains("failed after"));
+        assert!(message.contains("(connect,"), "{message}");
+        assert!(message.contains("azure_client_request_id="));
+        assert!(!message.contains("sig=secret"));
+    }
 }