feat(error): detect accessNotConfigured and guide users to enable APIs (#33)

* feat(error): detect accessNotConfigured and guide users to enable APIs

When the Google API returns a 403 with reason accessNotConfigured,
gws now:
- Extracts the GCP Console enable URL from the error message.
- Adds an optional enable_url field to the JSON error output.
- Prints an actionable hint with the enable URL to stderr.

Also adds extract_enable_url() helper with tests, and a Troubleshooting
section to README.

Fixes #31

* fix(error): trim trailing punctuation from accessNotConfigured enable URL

.changeset/access-not-configured-guidance.md

@@ -0,0 +1,20 @@
+---
+"@googleworkspace/cli": patch
+---
+
+feat(error): detect disabled APIs and guide users to enable them
+
+When the Google API returns a 403 `accessNotConfigured` error (i.e., the
+required API has not been enabled for the GCP project), `gws` now:
+
+- Extracts the GCP Console enable URL from the error message body.
+- Prints the original error JSON to stdout (machine-readable, unchanged shape
+  except for an optional new `enable_url` field added to the error object).
+- Prints a human-readable hint with the direct enable URL to stderr, along
+  with instructions to retry after enabling.
+
+This prevents a dead-end experience where users see a raw 403 JSON blob
+with no guidance. The JSON output is backward-compatible; only an optional
+`enable_url` field is added when the URL is parseable from the message.
+
+Fixes #31

README.md

@@ -264,6 +264,42 @@ gws gmail users messages get --params '...' \
 All output — success, errors, download metadata — is structured JSON.
 
 
+## Troubleshooting
+
+### API not enabled — `accessNotConfigured`
+
+If a required Google API is not enabled for your GCP project, you will see a
+403 error with reason `accessNotConfigured`:
+
+```json
+{
+  "error": {
+    "code": 403,
+    "message": "Gmail API has not been used in project 549352339482 ...",
+    "reason": "accessNotConfigured",
+    "enable_url": "https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482"
+  }
+}
+```
+
+`gws` also prints an actionable hint to **stderr**:
+
+```
+💡 API not enabled for your GCP project.
+   Enable it at: https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482
+   After enabling, wait a few seconds and retry your command.
+```
+
+**Steps to fix:**
+1. Click the `enable_url` link (or copy it from the `enable_url` JSON field).
+2. In the GCP Console, click **Enable**.
+3. Wait ~10 seconds, then retry your `gws` command.
+
+> [!TIP]
+> You can also run `gws setup` which walks you through enabling all required
+> APIs for your project automatically.
+
+
 ## Development
 
 ```bash

src/error.rs

@@ -22,6 +22,8 @@ pub enum GwsError {
         code: u16,
         message: String,
         reason: String,
+        /// For `accessNotConfigured` errors: the GCP console URL to enable the API.
+        enable_url: Option<String>,
     },
 
     #[error("{0}")]
@@ -44,13 +46,20 @@ impl GwsError {
                 code,
                 message,
                 reason,
-            } => json!({
-                "error": {
+                enable_url,
+            } => {
+                let mut error_obj = json!({
                     "code": code,
                     "message": message,
                     "reason": reason,
+                });
+                // Include enable_url in JSON output when present (accessNotConfigured errors).
+                // This preserves machine-readable compatibility while adding new optional field.
+                if let Some(url) = enable_url {
+                    error_obj["enable_url"] = json!(url);
                 }
-            }),
+                json!({ "error": error_obj })
+            }
             GwsError::Validation(msg) => json!({
                 "error": {
                     "code": 400,
@@ -84,12 +93,33 @@ impl GwsError {
 }
 
 /// Formats any error as a JSON object and prints to stdout.
+///
+/// For `accessNotConfigured` errors (HTTP 403, reason `accessNotConfigured`),
+/// additional human-readable guidance is printed to stderr explaining how to
+/// enable the API in GCP. The JSON output on stdout is unchanged (machine-readable).
 pub fn print_error_json(err: &GwsError) {
     let json = err.to_json();
     println!(
         "{}",
         serde_json::to_string_pretty(&json).unwrap_or_default()
     );
+
+    // Print actionable guidance to stderr for accessNotConfigured errors
+    if let GwsError::Api {
+        reason, enable_url, ..
+    } = err
+    {
+        if reason == "accessNotConfigured" {
+            eprintln!();
+            eprintln!("💡 API not enabled for your GCP project.");
+            if let Some(url) = enable_url {
+                eprintln!("   Enable it at: {url}");
+            } else {
+                eprintln!("   Visit the GCP Console → APIs & Services → Library to enable the required API.");
+            }
+            eprintln!("   After enabling, wait a few seconds and retry your command.");
+        }
+    }
 }
 
 #[cfg(test)]
@@ -102,11 +132,13 @@ mod tests {
             code: 404,
             message: "Not Found".to_string(),
             reason: "notFound".to_string(),
+            enable_url: None,
         };
         let json = err.to_json();
         assert_eq!(json["error"]["code"], 404);
         assert_eq!(json["error"]["message"], "Not Found");
         assert_eq!(json["error"]["reason"], "notFound");
+        assert!(json["error"]["enable_url"].is_null());
     }
 
     #[test]
@@ -144,4 +176,38 @@ mod tests {
         assert_eq!(json["error"]["message"], "Something went wrong");
         assert_eq!(json["error"]["reason"], "internalError");
     }
+
+    // --- accessNotConfigured tests ---
+
+    #[test]
+    fn test_error_to_json_access_not_configured_with_url() {
+        let err = GwsError::Api {
+            code: 403,
+            message: "Gmail API has not been used in project 549352339482 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482 then retry.".to_string(),
+            reason: "accessNotConfigured".to_string(),
+            enable_url: Some("https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482".to_string()),
+        };
+        let json = err.to_json();
+        assert_eq!(json["error"]["code"], 403);
+        assert_eq!(json["error"]["reason"], "accessNotConfigured");
+        assert_eq!(
+            json["error"]["enable_url"],
+            "https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482"
+        );
+    }
+
+    #[test]
+    fn test_error_to_json_access_not_configured_without_url() {
+        let err = GwsError::Api {
+            code: 403,
+            message: "API not enabled.".to_string(),
+            reason: "accessNotConfigured".to_string(),
+            enable_url: None,
+        };
+        let json = err.to_json();
+        assert_eq!(json["error"]["code"], 403);
+        assert_eq!(json["error"]["reason"], "accessNotConfigured");
+        // enable_url key should not appear in JSON when None
+        assert!(json["error"]["enable_url"].is_null());
+    }
 }

src/executor.rs

@@ -500,6 +500,27 @@ fn build_url(
     Ok((full_url, query_params))
 }
 
+/// Attempts to extract a GCP console enable URL from a Google API `accessNotConfigured`
+/// error message.
+///
+/// The message format is typically:
+/// `"<API> has not been used in project <N> before or it is disabled. Enable it by visiting <URL> then retry."`
+///
+/// Returns the URL string if found, otherwise `None`.
+pub fn extract_enable_url(message: &str) -> Option<String> {
+    // Look for "visiting <URL>" pattern
+    let after_visiting = message.split("visiting ").nth(1)?;
+    // URL ends at the next whitespace character
+    let url = after_visiting
+        .split_whitespace()
+        .next()
+        .map(|s| {
+            s.trim_end_matches(|c: char| ['.', ',', ';', ':', ')', ']', '"', '\''].contains(&c))
+        })
+        .filter(|s| s.starts_with("http"))?;
+    Some(url.to_string())
+}
+
 fn handle_error_response(
     status: reqwest::StatusCode,
     error_body: &str,
@@ -526,19 +547,30 @@ fn handle_error_response(
                 .and_then(|m| m.as_str())
                 .unwrap_or("Unknown error")
                 .to_string();
+
+            // Reason can appear in "errors[0].reason" or at the top-level "reason" field.
             let reason = err_obj
                 .get("errors")
                 .and_then(|e| e.as_array())
                 .and_then(|arr| arr.first())
                 .and_then(|e| e.get("reason"))
                 .and_then(|r| r.as_str())
+                .or_else(|| err_obj.get("reason").and_then(|r| r.as_str()))
                 .unwrap_or("unknown")
                 .to_string();
 
+            // For accessNotConfigured, extract the GCP enable URL from the message.
+            let enable_url = if reason == "accessNotConfigured" {
+                extract_enable_url(&message)
+            } else {
+                None
+            };
+
             return Err(GwsError::Api {
                 code,
                 message,
                 reason,
+                enable_url,
             });
         }
     }
@@ -547,6 +579,7 @@ fn handle_error_response(
         code: status.as_u16(),
         message: error_body.to_string(),
         reason: "httpError".to_string(),
+        enable_url: None,
     })
 }
 
@@ -1130,6 +1163,7 @@ mod tests {
                 code,
                 message,
                 reason,
+                ..
             } => {
                 assert_eq!(code, 400);
                 assert_eq!(message, "Bad Request");
@@ -1275,6 +1309,7 @@ fn test_handle_error_response_non_json() {
             code,
             message,
             reason,
+            ..
         } => {
             assert_eq!(code, 500);
             assert_eq!(message, "Internal Server Error Text");
@@ -1284,6 +1319,108 @@ fn test_handle_error_response_non_json() {
     }
 }
 
+#[test]
+fn test_extract_enable_url_typical_message() {
+    let msg = "Gmail API has not been used in project 549352339482 before or it is disabled. \
+               Enable it by visiting https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482 then retry.";
+    let url = extract_enable_url(msg);
+    assert_eq!(
+        url.as_deref(),
+        Some("https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482")
+    );
+}
+
+#[test]
+fn test_extract_enable_url_no_url() {
+    let msg = "API not enabled.";
+    assert_eq!(extract_enable_url(msg), None);
+}
+
+#[test]
+fn test_extract_enable_url_non_http() {
+    let msg = "Enable it by visiting ftp://example.com then retry.";
+    assert_eq!(extract_enable_url(msg), None);
+}
+
+#[test]
+fn test_extract_enable_url_trims_trailing_punctuation() {
+    let msg = "Enable it by visiting https://console.cloud.google.com/apis/library?project=test123. Then retry.";
+    let url = extract_enable_url(msg);
+    assert_eq!(
+        url.as_deref(),
+        Some("https://console.cloud.google.com/apis/library?project=test123")
+    );
+}
+
+#[test]
+fn test_handle_error_response_access_not_configured_with_url() {
+    // Matches the top-level "reason" field format Google actually returns for this error
+    let json_err = serde_json::json!({
+        "error": {
+            "code": 403,
+            "message": "Gmail API has not been used in project 549352339482 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482 then retry.",
+            "status": "PERMISSION_DENIED",
+            "reason": "accessNotConfigured"
+        }
+    })
+    .to_string();
+
+    let err = handle_error_response(
+        reqwest::StatusCode::FORBIDDEN,
+        &json_err,
+        &AuthMethod::OAuth,
+    )
+    .unwrap_err();
+
+    match err {
+        GwsError::Api {
+            code,
+            reason,
+            enable_url,
+            ..
+        } => {
+            assert_eq!(code, 403);
+            assert_eq!(reason, "accessNotConfigured");
+            assert_eq!(
+                enable_url.as_deref(),
+                Some("https://console.developers.google.com/apis/api/gmail.googleapis.com/overview?project=549352339482")
+            );
+        }
+        _ => panic!("Expected Api error"),
+    }
+}
+
+#[test]
+fn test_handle_error_response_access_not_configured_errors_array() {
+    // Some Google APIs put reason in errors[0].reason
+    let json_err = serde_json::json!({
+        "error": {
+            "code": 403,
+            "message": "Drive API has not been used in project 12345 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/drive.googleapis.com/overview?project=12345 then retry.",
+            "errors": [{ "reason": "accessNotConfigured" }]
+        }
+    })
+    .to_string();
+
+    let err = handle_error_response(
+        reqwest::StatusCode::FORBIDDEN,
+        &json_err,
+        &AuthMethod::OAuth,
+    )
+    .unwrap_err();
+
+    match err {
+        GwsError::Api {
+            reason, enable_url, ..
+        } => {
+            assert_eq!(reason, "accessNotConfigured");
+            assert!(enable_url.is_some());
+            assert!(enable_url.unwrap().contains("drive.googleapis.com"));
+        }
+        _ => panic!("Expected Api error"),
+    }
+}
+
 #[test]
 fn test_get_value_type_helper() {
     assert_eq!(get_value_type(&json!(null)), "null");

src/helpers/calendar.rs

@@ -248,6 +248,7 @@ async fn handle_agenda(matches: &ArgMatches) -> Result<(), GwsError> {
             code: 0,
             message: err,
             reason: "calendarList_failed".to_string(),
+            enable_url: None,
         });
     }
 

src/helpers/events/subscribe.rs

@@ -153,6 +153,7 @@ pub(super) async fn handle_subscribe(
                     code: 400,
                     message: format!("Failed to create Pub/Sub topic: {body}"),
                     reason: "pubsubError".to_string(),
+                    enable_url: None,
                 });
             }
 
@@ -177,6 +178,7 @@ pub(super) async fn handle_subscribe(
                     code: 400,
                     message: format!("Failed to create Pub/Sub subscription: {body}"),
                     reason: "pubsubError".to_string(),
+                    enable_url: None,
                 });
             }
 
@@ -339,6 +341,7 @@ async fn pull_loop(
                 code: 400,
                 message: format!("Pub/Sub pull failed: {body}"),
                 reason: "pubsubError".to_string(),
+                enable_url: None,
             });
         }
 

src/helpers/gmail/triage.rs

@@ -56,6 +56,7 @@ pub async fn handle_triage(matches: &ArgMatches) -> Result<(), GwsError> {
             code: 0,
             message: err,
             reason: "list_failed".to_string(),
+            enable_url: None,
         });
     }
 

src/helpers/gmail/watch.rs

@@ -58,6 +58,7 @@ pub(super) async fn handle_watch(
                     code: 400,
                     message: format!("Failed to create Pub/Sub topic: {body}"),
                     reason: "pubsubError".to_string(),
+                    enable_url: None,
                 });
             }
 
@@ -122,6 +123,7 @@ pub(super) async fn handle_watch(
                 code: 400,
                 message: format!("Failed to create Pub/Sub subscription: {body}"),
                 reason: "pubsubError".to_string(),
+                enable_url: None,
             });
         }
 
@@ -157,6 +159,7 @@ pub(super) async fn handle_watch(
                     serde_json::to_string(err).unwrap_or_default()
                 ),
                 reason: "gmailError".to_string(),
+                enable_url: None,
             });
         }
 
@@ -282,6 +285,7 @@ async fn watch_pull_loop(
                 code: 400,
                 message: format!("Pub/Sub pull failed: {body}"),
                 reason: "pubsubError".to_string(),
+                enable_url: None,
             });
         }
 

src/helpers/workflows.rs

@@ -249,6 +249,7 @@ async fn get_json(
             code: status.as_u16(),
             message: body,
             reason: "workflow_request_failed".to_string(),
+            enable_url: None,
         });
     }
 
@@ -516,6 +517,7 @@ async fn handle_email_to_task(matches: &ArgMatches) -> Result<(), GwsError> {
             code: status.as_u16(),
             message: body,
             reason: "task_create_failed".to_string(),
+            enable_url: None,
         });
     }
 
@@ -671,6 +673,7 @@ async fn handle_file_announce(matches: &ArgMatches) -> Result<(), GwsError> {
             code: status.as_u16(),
             message: body,
             reason: "chat_send_failed".to_string(),
+            enable_url: None,
         });
     }