review-comment: Fix form-urlencoded percent-decoding fallback

#7585 (comment)

Author: 43jay

Sources/Swift/Integrations/SessionReplay/SentryReplayNetworkDetails.swift

@@ -161,13 +161,8 @@ enum NetworkBodyWarning: String {
                     warnings.append(.bodyParseError)
                     return parseText(data, encoding: encoding, warnings: &warnings)
                 }
-                // In form-urlencoded, + means space (rdar://40751862).
-                let key = comps[0]
-                    .replacingOccurrences(of: "+", with: " ")
-                    .removingPercentEncoding ?? comps[0]
-                let value = comps.dropFirst().joined(separator: "=")
-                    .replacingOccurrences(of: "+", with: " ")
-                    .removingPercentEncoding ?? comps[1]
+                let key = decodeFormComponent(comps[0])
+                let value = decodeFormComponent(comps.dropFirst().joined(separator: "="))
                 guard !key.isEmpty else { continue }
                 if let existing = formData[key] {
                     if var list = existing as? [String] {
@@ -183,6 +178,13 @@ enum NetworkBodyWarning: String {
             return Body(content: formData, warnings: warnings)
         }
 
+        /// Decodes a form-urlencoded component: converts `+` to space and removes percent-encoding.
+        /// Falls back to the `+`-to-space result if percent-decoding fails (e.g. `%ZZ`).
+        private static func decodeFormComponent(_ component: String) -> String {
+            let plusDecoded = component.replacingOccurrences(of: "+", with: " ")
+            return plusDecoded.removingPercentEncoding ?? plusDecoded
+        }
+
         private static func parseText(_ data: Data, encoding: String.Encoding = .utf8, warnings: inout [NetworkBodyWarning]) -> Body {
             // Truncation at a multi-byte boundary (e.g. UTF-8 CJK, emoji) makes
             // String(data:encoding:) return nil. Try dropping up to 3 trailing bytes

Tests/SentryTests/Networking/SentryReplayNetworkDetailsBodyTests.swift

@@ -295,6 +295,20 @@ class SentryReplayNetworkDetailsBodyTests: XCTestCase {
         XCTAssertEqual(dict["name"] as? String, "Jane Doe")
     }
 
+    func testFormEncoded_malformedPercentEncoding_shouldPreservePlusDecodingAndEquals() throws {
+        // %ZZ is invalid percent-encoding → removingPercentEncoding returns nil.
+        // The fallback should still preserve +-to-space and = in values.
+        let body = try XCTUnwrap(Body(
+            data: "key=a%ZZ=b&greeting=hello+world".data(using: .utf8)!,
+            contentType: "application/x-www-form-urlencoded; charset=utf-8"
+        ))
+
+        let dict = try XCTUnwrap(body.serialize()["body"] as? [String: Any])
+        // Value preserves the joined "=" and the +-to-space conversion on the valid pair
+        XCTAssertEqual(dict["key"] as? String, "a%ZZ=b")
+        XCTAssertEqual(dict["greeting"] as? String, "hello world")
+    }
+
     // MARK: - Multi-byte Truncation
 
     func testInit_withTruncatedMultiByteUTF8_shouldRecoverValidPrefix() throws {