diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index e19da74..340e54f 100644
--- a/.jules/sentinel.md
+++ b/.jules/sentinel.md
@@ -12,3 +12,7 @@
 **Vulnerability:** A process can block (deadlock) when its stdout/stderr pipe fills before the parent reads it, because the child blocks on `write()` while the parent blocks on `waitUntilExit()`.
 **Learning:** `pipe.fileHandleForReading.readDataToEndOfFile()` after `process.waitUntilExit()` is the deadlock pattern. Default macOS pipe buffer is ~64KB.
 **Prevention:** Read the pipe before/concurrently-with waiting for exit. The simplest pattern is to perform the read inside the same background queue that calls `waitUntilExit()`, capturing the bytes for the caller to use after the dispatch group resolves.
+## 2024-05-16 - Webhook Insecure HTTP Scheme Allowed
+**Vulnerability:** Autopilot configuration allowed `http` schemes for webhook URLs, risking insecure unencrypted transmission of sensitive daemon alerts.
+**Learning:** Validation logic incorrectly whitelisted both `http` and `https`, likely copy-pasted from generic URL validation instead of enforcing secure-by-default for webhooks.
+**Prevention:** Always enforce `https` scheme for outbound webhooks handling alert payloads and align validation logic with parsing logic.
diff --git a/Sources/Cacheout/Headless/StatusSocket.swift b/Sources/Cacheout/Headless/StatusSocket.swift
index 12c516e..cb084cd 100644
--- a/Sources/Cacheout/Headless/StatusSocket.swift
+++ b/Sources/Cacheout/Headless/StatusSocket.swift
@@ -708,8 +708,8 @@ public enum AutopilotConfigValidator {
             if let urlStr = webhook["url"] as? String {
                 if let url = URL(string: urlStr) {
                     let scheme = url.scheme?.lowercased() ?? ""
-                    if scheme != "http" && scheme != "https" {
-                        errors.append("webhook: url must use http or https scheme, got '\(scheme)'")
+                    if scheme != "https" {
+                        errors.append("webhook: url must use https scheme for security, got '\(scheme)'")
                     }
                     if url.host == nil || url.host?.isEmpty == true {
                         errors.append("webhook: url must be an absolute URL with a host")
diff --git a/Sources/Cacheout/Headless/WebhookAlerter.swift b/Sources/Cacheout/Headless/WebhookAlerter.swift
index 8fa8a8e..1ddfb94 100644
--- a/Sources/Cacheout/Headless/WebhookAlerter.swift
+++ b/Sources/Cacheout/Headless/WebhookAlerter.swift
@@ -336,7 +336,8 @@ extension WebhookAlerter.WebhookConfig {
     public static func parse(from json: [String: Any]) -> WebhookAlerter.WebhookConfig? {
         guard let webhook = json["webhook"] as? [String: Any],
               let urlStr = webhook["url"] as? String,
-              let url = URL(string: urlStr) else {
+              let url = URL(string: urlStr),
+              url.scheme?.lowercased() == "https" else {
             return nil
         }
         let format = webhook["format"] as? String ?? "generic"
diff --git a/Tests/CacheoutTests/HeadlessTests.swift b/Tests/CacheoutTests/HeadlessTests.swift
index ca8ccae..49f1611 100644
--- a/Tests/CacheoutTests/HeadlessTests.swift
+++ b/Tests/CacheoutTests/HeadlessTests.swift
@@ -540,6 +540,18 @@ final class AutopilotConfigValidatorTests: XCTestCase {
         XCTAssertTrue(errors.contains { $0.contains("webhook: missing") && $0.contains("timeout_s") })
     }
 
+    func testWebhookInsecureURLRejected() {
+        let json = """
+        {
+            "version": 1,
+            "enabled": true,
+            "webhook": {"url": "http://x.com", "format": "generic", "timeout_s": 5}
+        }
+        """.data(using: .utf8)!
+        let errors = AutopilotConfigValidator.validate(data: json)
+        XCTAssertTrue(errors.contains { $0.contains("https scheme") })
+    }
+
     func testWebhookInvalidFormat() {
         let json = """
         {