fix: add appium: vendor prefix to iOS capabilities for Appium v3 (#810)

* fix: add appium: vendor prefix to iOS capabilities for Appium v3

Appium v3 enforces the W3C WebDriver spec strictly, requiring
non-standard capabilities to use vendor prefixes. The iOS provider
was sending capabilities like `automationName`, `noReset`, `deviceName`,
`platformVersion`, and `udid` without the required `appium:` prefix,
causing session creation to fail with InvalidArgumentError.

This change prefixes all non-standard capabilities with `appium:` while
leaving standard W3C capabilities (`platformName`, `browserName`)
unprefixed. Backwards-compatible with Appium v2, which accepts both
formats.

Fixes #629

* fix: extract build_ios_capabilities for testable production code path

Addresses review feedback: removes unused `mut manager` warning and
validates the actual capability-building logic instead of reconstructing
JSON inline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/native/webdriver/appium.rs

@@ -40,32 +40,45 @@ impl AppiumManager {
         })
     }
 
+    pub fn build_ios_capabilities(
+        device_udid: Option<&str>,
+        device_name: Option<&str>,
+        platform_version: Option<&str>,
+    ) -> Value {
+        let mut caps = json!({
+            "platformName": "iOS",
+            "appium:automationName": "XCUITest",
+            "browserName": "Safari",
+            "appium:noReset": true,
+        });
+
+        if let Some(name) = device_name {
+            caps["appium:deviceName"] = json!(name);
+        } else {
+            caps["appium:deviceName"] = json!("iPhone");
+        }
+
+        if let Some(ver) = platform_version {
+            caps["appium:platformVersion"] = json!(ver);
+        }
+
+        if let Some(udid) = device_udid {
+            caps["appium:udid"] = json!(udid);
+        }
+
+        caps
+    }
+
     pub async fn create_ios_session(
         &mut self,
         device_name: Option<&str>,
         platform_version: Option<&str>,
     ) -> Result<Value, String> {
-        let mut caps = json!({
+        let caps = Self::build_ios_capabilities(
-            "platformName": "iOS",
+            self.device_udid.as_deref(),
-            "automationName": "XCUITest",
+            device_name,
-            "browserName": "Safari",
+            platform_version,
-            "noReset": true,
+        );
-        });
-
-        if let Some(name) = device_name {
-            caps["deviceName"] = json!(name);
-        } else {
-            caps["deviceName"] = json!("iPhone");
-        }
-
-        if let Some(ver) = platform_version {
-            caps["platformVersion"] = json!(ver);
-        }
-
-        if let Some(ref udid) = self.device_udid {
-            caps["udid"] = json!(udid);
-        }
-
         self.client.create_session(caps).await
     }
 
@@ -198,4 +211,30 @@ mod tests {
         assert_eq!(APPIUM_DEFAULT_PORT, 4723);
         assert_eq!(APPIUM_STARTUP_TIMEOUT_SECS, 30);
     }
+
+    #[test]
+    fn test_ios_capabilities_use_vendor_prefix() {
+        let caps = AppiumManager::build_ios_capabilities(
+            Some("TEST-UDID-123"),
+            Some("iPhone 16 Pro"),
+            Some("18.5"),
+        );
+
+        // W3C standard capabilities must NOT have vendor prefix
+        assert!(caps.get("platformName").is_some());
+        assert!(caps.get("browserName").is_some());
+
+        // Non-standard capabilities MUST have appium: vendor prefix
+        assert!(caps.get("appium:automationName").is_some());
+        assert!(caps.get("appium:noReset").is_some());
+        assert!(caps.get("appium:deviceName").is_some());
+        assert!(caps.get("appium:platformVersion").is_some());
+        assert!(caps.get("appium:udid").is_some());
+
+        // Must NOT have unprefixed non-standard capabilities
+        assert!(caps.get("automationName").is_none());
+        assert!(caps.get("noReset").is_none());
+        assert!(caps.get("deviceName").is_none());
+        assert!(caps.get("udid").is_none());
+    }
 }