diff --git a/lisp/security-dispatcher.lisp b/lisp/security-dispatcher.lisp
index 21fdb0b..e3f4048 100644
--- a/lisp/security-dispatcher.lisp
+++ b/lisp/security-dispatcher.lisp
@@ -23,7 +23,9 @@
     ".kube/config" "kubeconfig"
     "*.cert" "*.crt" "*.csr"
     "*password*" "*passwd*")
-  "Path patterns blocked from file reads.")
+  "Path patterns blocked from file reads.
+Core file protection (core-*.org, core-*.lisp) handled separately by
+dispatcher-check-core-path for self-build safety.")
 
 (defvar *dispatcher-exposure-patterns*
   '((:pem-key "-----BEGIN +(RSA|DSA|EC|OPENSSH|PGP) +PRIVATE +KEY *-----")
@@ -60,6 +62,12 @@
                 "\\*" (cl-ppcre:quote-meta-chars pattern) ".*")))
     (cl-ppcre:scan regex path)))
 
+(defun dispatcher-check-core-path (filepath)
+  "Returns T if FILEPATH matches a core-* self-build protected pattern."
+  (when (and filepath (stringp filepath))
+    (or (and (>= (length filepath) 5) (string-equal (subseq filepath 0 5) "core-"))
+        (cl-ppcre:scan "core-.*\\.(org|lisp)" filepath))))
+
 (defun dispatcher-check-secret-path (filepath)
   "Returns the matching pattern if FILEPATH matches a protected path, nil otherwise."
   (when (and filepath (stringp filepath))
@@ -229,6 +237,15 @@ privacy tags, privacy text, shell safety, network exfil, high-impact approval."
                :payload (list :level :error
                               :text (format nil "Action blocked: Attempted read of protected path '~a'" filepath)))))
 
+      ;; Vector 2b: Self-build safety — core file writes require HITL approval
+      ((and filepath content
+            (string-equal (uiop:getenv "SELF_BUILD_MODE") "true")
+            (dispatcher-check-core-path filepath))
+       (log-message "SELF-BUILD: Core file write to '~a' requires approval" filepath)
+       (list :type :EVENT :level :approval-required
+             :payload (list :sensor :approval-required :action action
+                            :message (format nil "Core file write blocked: '~a' requires HITL approval via Flight Plan." filepath))))
+
       ;; Vector 3: Content contains secret patterns
       ((and text (dispatcher-exposure-scan text))
        (let ((matched (dispatcher-exposure-scan text)))
@@ -429,6 +446,22 @@ Recognized formats:
   (is (dispatcher-check-secret-path "id_rsa"))
   (is (not (dispatcher-check-secret-path "README.org"))))
 
+(test test-self-build-core-protection
+  "Contract v0.4.0: core-* paths are protected; write produces approval-required in SELF_BUILD_MODE."
+  ;; Core paths are recognized
+  (is (passepartout::dispatcher-check-core-path "core-loop-reason.org"))
+  (is (passepartout::dispatcher-check-core-path "core-memory.lisp"))
+  (is (not (passepartout::dispatcher-check-core-path "gateway-tui-view.org")))
+  ;; With SELF_BUILD_MODE=true, core writes produce approval-required
+  (let ((action '(:type :REQUEST :target :tool :payload (:tool "write-file" :args (:filepath "core-loop-reason.org" :content "x")))))
+    (setf (uiop:getenv "SELF_BUILD_MODE") "true")
+    (let ((result (dispatcher-check action nil)))
+      (is (eq :approval-required (getf result :level)))
+      (setf (uiop:getenv "SELF_BUILD_MODE") "false"))
+    ;; With SELF_BUILD_MODE=false (default), writes pass through
+    (let ((result (dispatcher-check action nil)))
+      (is (eq :REQUEST (getf result :type))))))
+
 (test test-check-shell-safety
   "Contract 3: dispatcher-check-shell-safety detects dangerous commands."
   (is (dispatcher-check-shell-safety "rm -rf /"))
diff --git a/org/security-dispatcher.org b/org/security-dispatcher.org
index 3bf153e..f0d15ec 100644
--- a/org/security-dispatcher.org
+++ b/org/security-dispatcher.org
@@ -95,7 +95,9 @@ Path patterns (with * wildcards) that are blocked from file reads. Covers SSH ke
     ".kube/config" "kubeconfig"
     "*.cert" "*.crt" "*.csr"
     "*password*" "*passwd*")
-  "Path patterns blocked from file reads.")
+  "Path patterns blocked from file reads.
+Core file protection (core-*.org, core-*.lisp) handled separately by
+dispatcher-check-core-path for self-build safety.")
 #+end_src
 
 ** Content exposure patterns (*dispatcher-exposure-patterns*)
@@ -157,6 +159,15 @@ Destructive and injection patterns that are blocked in shell commands. Covers ~r
     (cl-ppcre:scan regex path)))
 
 #+end_src
+** dispatcher-check-core-path
+;; REPL-VERIFIED: 2026-05-06T18:00:00
+#+begin_src lisp
+(defun dispatcher-check-core-path (filepath)
+  "Returns T if FILEPATH matches a core-* self-build protected pattern."
+  (when (and filepath (stringp filepath))
+    (or (and (>= (length filepath) 5) (string-equal (subseq filepath 0 5) "core-"))
+        (cl-ppcre:scan "core-.*\\.(org|lisp)" filepath))))
+#+end_src
 ** dispatcher-check-secret-path
 ;; REPL-VERIFIED: 2026-05-03T13:00:00
 #+begin_src lisp
@@ -377,6 +388,15 @@ privacy tags, privacy text, shell safety, network exfil, high-impact approval."
                :payload (list :level :error
                               :text (format nil "Action blocked: Attempted read of protected path '~a'" filepath)))))
 
+      ;; Vector 2b: Self-build safety — core file writes require HITL approval
+      ((and filepath content
+            (string-equal (uiop:getenv "SELF_BUILD_MODE") "true")
+            (dispatcher-check-core-path filepath))
+       (log-message "SELF-BUILD: Core file write to '~a' requires approval" filepath)
+       (list :type :EVENT :level :approval-required
+             :payload (list :sensor :approval-required :action action
+                            :message (format nil "Core file write blocked: '~a' requires HITL approval via Flight Plan." filepath))))
+
       ;; Vector 3: Content contains secret patterns
       ((and text (dispatcher-exposure-scan text))
        (let ((matched (dispatcher-exposure-scan text)))
@@ -646,6 +666,22 @@ Recognized formats:
   (is (dispatcher-check-secret-path "id_rsa"))
   (is (not (dispatcher-check-secret-path "README.org"))))
 
+(test test-self-build-core-protection
+  "Contract v0.4.0: core-* paths are protected; write produces approval-required in SELF_BUILD_MODE."
+  ;; Core paths are recognized
+  (is (passepartout::dispatcher-check-core-path "core-loop-reason.org"))
+  (is (passepartout::dispatcher-check-core-path "core-memory.lisp"))
+  (is (not (passepartout::dispatcher-check-core-path "gateway-tui-view.org")))
+  ;; With SELF_BUILD_MODE=true, core writes produce approval-required
+  (let ((action '(:type :REQUEST :target :tool :payload (:tool "write-file" :args (:filepath "core-loop-reason.org" :content "x")))))
+    (setf (uiop:getenv "SELF_BUILD_MODE") "true")
+    (let ((result (dispatcher-check action nil)))
+      (is (eq :approval-required (getf result :level)))
+      (setf (uiop:getenv "SELF_BUILD_MODE") "false"))
+    ;; With SELF_BUILD_MODE=false (default), writes pass through
+    (let ((result (dispatcher-check action nil)))
+      (is (eq :REQUEST (getf result :type))))))
+
 (test test-check-shell-safety
   "Contract 3: dispatcher-check-shell-safety detects dangerous commands."
   (is (dispatcher-check-shell-safety "rm -rf /"))