(defun self-fix-replace-all (string part replacement)
  (with-output-to-string (out)
    (loop with part-length = (length part)
          for old-pos = 0 then (+ pos part-length)
          for pos = (search part string :start2 old-pos)
          do (write-string string out :start old-pos :end (or pos (length string)))
          when pos do (write-string replacement out)
          while pos)))

(defun self-fix-apply (action context)
  "Applies a surgical code fix directly to the target file."
  (declare (ignore context))
  (let* ((payload (getf action :payload))
         (target-file (getf payload :file))
         (old-code (getf payload :old))
         (new-code (getf payload :new)))
    (org-agent:kernel-log "SELF-FIX - Attempting surgical fix on ~a..." target-file)
    (if (uiop:file-exists-p target-file)
        (let ((content (uiop:read-file-string target-file)))
          (if (search old-code content)
              (let ((new-content (self-fix-replace-all content old-code new-code)))
                (with-open-file (out target-file :direction :output :if-exists :supersede)
                  (write-string new-content out))
                (org-agent:kernel-log "SELF-FIX SUCCESS - Applied fix to ~a" target-file)
                t)
              (progn
                (org-agent:kernel-log "SELF-FIX FAILURE - Could not find old code in ~a" target-file)
                nil)))
        (progn
          (org-agent:kernel-log "SELF-FIX FAILURE - File not found: ~a" target-file)
          nil))))

(defun neuro-skill-self-fix (context)
  "Neural stage: Synthesizes a surgical code modification based on the hypothesis."
  (let* ((payload (getf context :payload))
         (hypothesis (getf payload :hypothesis))
         (failure-log (getf payload :failure-log)))
    (org-agent:ask-neuro 
     (format nil "Based on the hypothesis '~a' and failure '~a', provide the exact Lisp code to fix it. 
Return a Lisp plist: (:target :self-fix :action :apply :file \"path/to/file.lisp\" :old \"old code\" :new \"new code\")" 
             hypothesis failure-log)
     :system-prompt "You are the PSF Repair Actuator. You MUST return ONLY a Lisp plist.")))