fix(executor): add Content-Length: 0 for body-less POST requests (#183)

* fix(executor): add Content-Length: 0 header for body-less POST/PUT/PATCH requests

Google API servers return HTTP 411 (Length Required) when a POST request
is sent without a Content-Length header, even if there is no body.
This affects all Discovery API methods where httpMethod is POST but no
requestBody is defined (e.g. gmail users.messages.trash).

Fixes #182

* chore: add changeset for content-length fix

.changeset/fix-content-length-bodyless-post.md

@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+Add Content-Length: 0 header for POST/PUT/PATCH requests with no body to fix HTTP 411 errors

src/executor.rs

@@ -191,6 +191,8 @@ async fn build_http_request(
         } else if let Some(ref body_val) = input.body {
             request = request.header("Content-Type", "application/json");
             request = request.json(body_val);
+        } else if matches!(method.http_method.as_str(), "POST" | "PUT" | "PATCH") {
+            request = request.header("Content-Length", "0");
         }
     }
 
@@ -1817,3 +1819,84 @@ fn test_get_value_type_helper() {
     assert_eq!(get_value_type(&json!([1, 2])), "array");
     assert_eq!(get_value_type(&json!({"a": 1})), "object");
 }
+
+#[tokio::test]
+async fn test_post_without_body_sets_content_length_zero() {
+    let client = reqwest::Client::new();
+    let method = RestMethod {
+        http_method: "POST".to_string(),
+        path: "messages/trash".to_string(),
+        ..Default::default()
+    };
+    let input = ExecutionInput {
+        full_url: "https://example.com/messages/trash".to_string(),
+        body: None,
+        params: Map::new(),
+        query_params: HashMap::new(),
+        is_upload: false,
+    };
+
+    let request = build_http_request(&client, &method, &input, None, &AuthMethod::None, None, 0, None)
+        .await
+        .unwrap();
+
+    let built = request.build().unwrap();
+    assert_eq!(
+        built.headers().get("Content-Length").map(|v| v.to_str().unwrap()),
+        Some("0"),
+        "POST with no body must include Content-Length: 0"
+    );
+}
+
+#[tokio::test]
+async fn test_post_with_body_does_not_add_content_length_zero() {
+    let client = reqwest::Client::new();
+    let method = RestMethod {
+        http_method: "POST".to_string(),
+        path: "files".to_string(),
+        ..Default::default()
+    };
+    let input = ExecutionInput {
+        full_url: "https://example.com/files".to_string(),
+        body: Some(json!({"name": "test"})),
+        params: Map::new(),
+        query_params: HashMap::new(),
+        is_upload: false,
+    };
+
+    let request = build_http_request(&client, &method, &input, None, &AuthMethod::None, None, 0, None)
+        .await
+        .unwrap();
+
+    let built = request.build().unwrap();
+    // When body is present, Content-Length should NOT be "0"
+    let cl = built.headers().get("Content-Length").map(|v| v.to_str().unwrap().to_string());
+    assert!(cl.is_none() || cl.as_deref() != Some("0"));
+}
+
+#[tokio::test]
+async fn test_get_does_not_set_content_length_zero() {
+    let client = reqwest::Client::new();
+    let method = RestMethod {
+        http_method: "GET".to_string(),
+        path: "files".to_string(),
+        ..Default::default()
+    };
+    let input = ExecutionInput {
+        full_url: "https://example.com/files".to_string(),
+        body: None,
+        params: Map::new(),
+        query_params: HashMap::new(),
+        is_upload: false,
+    };
+
+    let request = build_http_request(&client, &method, &input, None, &AuthMethod::None, None, 0, None)
+        .await
+        .unwrap();
+
+    let built = request.build().unwrap();
+    assert!(
+        built.headers().get("Content-Length").is_none(),
+        "GET with no body should not have Content-Length header"
+    );
+}