feat: add spine-set-status, spine-add-note, spine-set-rating

spine.el

@@ -250,6 +250,81 @@ Signals an error on failure."
               t)
           (kill-buffer))))))
 
+(defun spine-set-status (id status)
+  "Set the TODO state of book with ID to STATUS.
+STATUS should be one of: WANT, READING, READ, ABANDONED.
+Signals an error if the book is not found."
+  (let ((org-file (expand-file-name spine-org-file)))
+    (unless (file-exists-p org-file)
+      (error "spine-set-status: file not found: %s" org-file))
+    (with-current-buffer (find-file-noselect org-file)
+      (unwind-protect
+          (progn
+            (org-element-map (org-element-parse-buffer 'headline) 'headline
+              (lambda (hl)
+                (when (= (org-element-property :level hl) 1)
+                  (let ((pos (org-element-property :begin hl)))
+                    (when (equal id (spine--prop pos "ID"))
+                      (goto-char pos)
+                      (org-todo status)))))
+              nil 'headline)
+            (unless (eq (point) (point-min))
+              (save-buffer)
+              t)
+            (when (eq (point) (point-min))
+              (error "spine-set-status: no book found with ID %s" id)))
+        (kill-buffer)))))
+
+(defun spine-add-note (id text &optional date)
+  "Append a reading note to the book with ID.
+TEXT is the note content. DATE is an optional YYYY-MM-DD string
+\(defaults to today). Signals an error if the book is not found."
+  (let ((org-file (expand-file-name spine-org-file))
+        (date-str (or date (format-time-string "%Y-%m-%d"))))
+    (unless (file-exists-p org-file)
+      (error "spine-add-note: file not found: %s" org-file))
+    (with-current-buffer (find-file-noselect org-file)
+      (unwind-protect
+          (progn
+            (org-element-map (org-element-parse-buffer 'headline) 'headline
+              (lambda (hl)
+                (when (= (org-element-property :level hl) 1)
+                  (let ((hl-id (spine--prop (org-element-property :begin hl) "ID")))
+                    (when (equal id hl-id)
+                      (goto-char (org-element-property :end hl))
+                      (skip-chars-backward " \t\n")
+                      (insert (format "\n- [%s] %s\n" date-str text))))))
+              nil 'headline)
+            (unless (eq (point) (point-min))
+              (save-buffer)
+              t)
+            (when (eq (point) (point-min))
+              (error "spine-add-note: no book found with ID %s" id)))
+        (kill-buffer)))))
+
+(defun spine-set-rating (id rating)
+  "Set the RATING property of book with ID to RATING (1-5 string).
+Signals an error if the book is not found."
+  (let ((org-file (expand-file-name spine-org-file)))
+    (unless (file-exists-p org-file)
+      (error "spine-set-rating: file not found: %s" org-file))
+    (with-current-buffer (find-file-noselect org-file)
+      (unwind-protect
+          (progn
+            (org-element-map (org-element-parse-buffer 'headline) 'headline
+              (lambda (hl)
+                (when (= (org-element-property :level hl) 1)
+                  (let ((pos (org-element-property :begin hl)))
+                    (when (equal id (spine--prop pos "ID"))
+                      (goto-char pos)
+                      (org-set-property "RATING" rating)))))
+              nil 'headline)
+            (unless (eq (point) (point-min))
+              (save-buffer)
+              t)
+            (when (eq (point) (point-min))
+              (error "spine-set-rating: no book found with ID %s" id)))
+        (kill-buffer)))))
 (defun spine--extract-notes (hl-begin hl-end)
   "Extract reading notes from headline body between HL-BEGIN and HL-END.
 Returns list of (date-string text-string) pairs."