Make prompt fontification configurable

README.md

@@ -173,6 +173,7 @@ Chat
 - `eca-chat-prompt-prefix-loading`: Prompt prefix string while a request is in progress.
 - `eca-chat-read-only-history`: Whether the chat history/output, the `---` separator and the task area are read-only so only the progress, `@`-context and prompt input lines stay editable (default `t`). Set to `nil` to keep the whole buffer writable.
 - `eca-chat-hide-markdown-markup`: Whether to hide markdown markup in chat buffers (default `t`). Set to `nil` to keep fences/backticks visible, which may avoid fenced code blocks jumping while typing or streaming.
+- `eca-chat-fontify-prompt`: Whether to apply Markdown fontification to prompt text (default `t`). Set to `nil` to skip prompt-area Markdown block scans in large chat buffers.
 - `eca-chat-history-page-size`: Number of newest messages to load when opening a persisted chat (default `50`). When non-nil, `eca-chat-resume` opens chats with a bounded window and shows a "Load older messages" control to page through earlier history on demand; set to `nil` to replay the entire history on open.
 - `eca-chat-context-prefix`: Prefix used for context references in the chat buffer (default `@`).
 - `eca-chat-filepath-prefix`: Prefix used for file path references in the chat buffer (default `#`).

eca-chat.el

@@ -325,12 +325,75 @@ typing or streaming."
   :type 'boolean
   :group 'eca)
 
+(defcustom eca-chat-fontify-prompt t
+  "Whether ECA chat applies Markdown fontification to prompt text.
+When non-nil, preserve the historical prompt rendering behavior.
+When nil, prompt edits skip Markdown block scans over chat history.
+Set this to nil if typing in large ECA chat buffers is slow."
+  :type 'boolean
+  :group 'eca)
+
 (defun eca-chat--apply-markdown-markup-visibility ()
   "Apply `eca-chat-hide-markdown-markup' in current buffer."
   (if eca-chat-hide-markdown-markup
       (add-to-invisibility-spec 'markdown-markup)
     (remove-from-invisibility-spec 'markdown-markup)))
 
+(defvar-local eca-chat--syntax-propertize-function nil
+  "Original syntax propertizer wrapped by ECA chat.")
+
+(defun eca-chat--fontification-history-end (end)
+  "Return END clipped at the prompt when prompt fontification is nil."
+  (if eca-chat-fontify-prompt
+      end
+    (if-let* ((prompt-start (eca-chat--prompt-area-start-point)))
+        (min end prompt-start)
+      end)))
+
+(defun eca-chat--syntax-propertize (beg end)
+  "Apply syntax properties from BEG to END, respecting prompt settings."
+  (let ((fontify-end (eca-chat--fontification-history-end end)))
+    (when (and eca-chat--syntax-propertize-function
+               (< beg fontify-end))
+      (funcall eca-chat--syntax-propertize-function beg fontify-end))))
+
+(defun eca-chat--font-lock-extend-region-function (beg end old-len)
+  "Extend Markdown font-lock region from BEG to END with OLD-LEN."
+  (when (fboundp 'markdown-font-lock-extend-region-function)
+    (if eca-chat-fontify-prompt
+        (markdown-font-lock-extend-region-function beg end old-len)
+      (let ((fontify-end (eca-chat--fontification-history-end end)))
+        (when (< beg fontify-end)
+          (markdown-font-lock-extend-region-function
+           beg fontify-end old-len))))))
+
+(defun eca-chat--syntax-propertize-extend-region-function (beg end)
+  "Extend Markdown syntax region from BEG to END, respecting prompt."
+  (when (fboundp 'markdown-syntax-propertize-extend-region)
+    (if eca-chat-fontify-prompt
+        (markdown-syntax-propertize-extend-region beg end)
+      (if-let* ((prompt-start (eca-chat--prompt-area-start-point)))
+          (when (<= end prompt-start)
+            (save-restriction
+              (narrow-to-region (point-min) prompt-start)
+              (markdown-syntax-propertize-extend-region beg end)))
+        (markdown-syntax-propertize-extend-region beg end)))))
+
+(defun eca-chat--install-fontification-overrides ()
+  "Install ECA chat fontification wrappers in current buffer."
+  (unless (eq syntax-propertize-function #'eca-chat--syntax-propertize)
+    (setq-local eca-chat--syntax-propertize-function syntax-propertize-function)
+    (setq-local syntax-propertize-function #'eca-chat--syntax-propertize))
+  (remove-hook 'syntax-propertize-extend-region-functions
+               #'markdown-syntax-propertize-extend-region t)
+  (add-hook 'syntax-propertize-extend-region-functions
+            #'eca-chat--syntax-propertize-extend-region-function nil t)
+  (remove-hook 'jit-lock-after-change-extend-region-functions
+               #'markdown-font-lock-extend-region-function t)
+  (add-hook 'jit-lock-after-change-extend-region-functions
+            #'eca-chat--font-lock-extend-region-function t t)
+  (setq-local font-lock-fontify-region-function #'eca-chat--fontify-region))
+
 (defvar-local eca-chat--tool-call-prepare-counters (make-hash-table :test 'equal)
   "Hash table mapping toolCall ID to message count.")
 
@@ -3167,11 +3230,13 @@ fontifier runs normally.
 
 Returns `(jit-lock-bounds BEG . END)' so jit-lock's bookkeeping
 matches the region we considered."
-  (let ((pos beg))
-    (while (< pos end)
+  (let ((pos beg)
+        (fontify-end (eca-chat--fontification-history-end end)))
+    (while (< pos fontify-end)
       (let ((skip (get-text-property pos 'eca-no-fontify))
-            (next (or (next-single-property-change pos 'eca-no-fontify nil end)
-                      end)))
+            (next (or (next-single-property-change
+                       pos 'eca-no-fontify nil fontify-end)
+                      fontify-end)))
         (unless skip
           (font-lock-default-fontify-region pos next loudly))
         (setq pos next))))
@@ -3549,10 +3614,12 @@ CHILD, NAME, DOCSTRING and BODY are passed down."
               (seq-difference font-lock-extra-managed-props
                               '(keymap help-echo mouse-face)))
 
-  ;; Skip font-lock on ranges tagged with `eca-no-fontify', currently
-  ;; used to stop gfm/markdown matchers from re-fontifying streaming
-  ;; tool-call argument bodies on every chunk (see #234).
-  (setq-local font-lock-fontify-region-function #'eca-chat--fontify-region)
+  ;; Keep chat fontification overrides together.  Skip font-lock on
+  ;; ranges tagged with `eca-no-fontify', which stops gfm/markdown
+  ;; matchers from re-fontifying streaming tool-call argument bodies on
+  ;; every chunk (see #234).  When configured, also skip prompt-area
+  ;; Markdown block scans during typing.
+  (eca-chat--install-fontification-overrides)
 
   (make-local-variable 'completion-at-point-functions)
   (setq-local completion-at-point-functions (list #'eca-chat-completion-at-point))

test/eca-chat-test.el

@@ -1055,6 +1055,200 @@ When MANUAL is non-nil the tool call requires manual approval."
                   :to-have-been-called-with 2 (point-max))
           (expect eca-chat--fontify-timer :to-be nil))))))
 
+(describe "eca-chat prompt fontification guard"
+  (it "keeps prompt markdown after-change extension enabled by default"
+    (with-temp-buffer
+      (let ((eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            markdown-called)
+        (eca-chat-mode)
+        (goto-char (eca-chat--prompt-field-start-point))
+        (expect eca-chat-fontify-prompt :to-be-truthy)
+        (cl-letf (((symbol-function 'markdown-font-lock-extend-region-function)
+                   (lambda (&rest _args)
+                     (setq markdown-called t))))
+          (run-hook-with-args 'jit-lock-after-change-extend-region-functions
+                              (point) (point) 0))
+        (expect markdown-called :to-be-truthy))))
+
+  (it "keeps prompt syntax propertize enabled by default"
+    (with-temp-buffer
+      (let ((eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (let ((prompt-start (eca-chat--prompt-field-start-point)))
+          (goto-char prompt-start)
+          (insert "prompt")
+          (expect eca-chat-fontify-prompt :to-be-truthy)
+          (setq-local eca-chat--syntax-propertize-function
+                      (lambda (beg end)
+                        (push (list beg end) calls)))
+          (funcall syntax-propertize-function prompt-start (point-max))
+          (expect (nreverse calls)
+                  :to-equal (list (list prompt-start (point-max))))))))
+
+  (it "wraps markdown syntax region extension in chat buffers"
+    (with-temp-buffer
+      (let ((eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t))
+        (eca-chat-mode)
+        (expect (memq #'eca-chat--syntax-propertize-extend-region-function
+                      syntax-propertize-extend-region-functions)
+                :to-be-truthy)
+        (expect (memq #'markdown-syntax-propertize-extend-region
+                      syntax-propertize-extend-region-functions)
+                :to-be nil))))
+
+  (it "keeps prompt syntax region extension enabled by default"
+    (with-temp-buffer
+      (let ((eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (goto-char (eca-chat--prompt-field-start-point))
+        (insert "prompt")
+        (expect eca-chat-fontify-prompt :to-be-truthy)
+        (cl-letf (((symbol-function 'markdown-syntax-propertize-extend-region)
+                   (lambda (beg end)
+                     (push (list beg end) calls)
+                     nil)))
+          (run-hook-wrapped 'syntax-propertize-extend-region-functions
+                            (lambda (fn)
+                              (funcall fn (point) (point-max))
+                              nil)))
+        (expect calls :to-be-truthy))))
+
+  (it "can skip markdown syntax extension for prompt syntax queries"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (save-excursion
+          (goto-char (eca-chat--content-insertion-point))
+          (eca-chat--insert (make-string 1000 ?x))
+          (eca-chat--insert "\n"))
+        (goto-char (eca-chat--prompt-field-start-point))
+        (insert "```\nprompt\n")
+        (cl-letf (((symbol-function 'markdown-syntax-propertize-extend-region)
+                   (lambda (beg end)
+                     (push (list beg end) calls)
+                     nil)))
+          (syntax-ppss-flush-cache (point-min))
+          (syntax-ppss (point)))
+        (expect calls :to-be nil))))
+
+  (it "still uses markdown syntax extension for history queries"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (save-excursion
+          (goto-char (eca-chat--content-insertion-point))
+          (eca-chat--insert (make-string 1000 ?x))
+          (eca-chat--insert "\n"))
+        (goto-char (point-min))
+        (forward-char 10)
+        (let ((prompt-start (eca-chat--prompt-area-start-point)))
+          (cl-letf (((symbol-function 'markdown-syntax-propertize-extend-region)
+                     (lambda (beg end)
+                       (push (list beg end (point-max)) calls)
+                       nil)))
+            (syntax-ppss-flush-cache (point-min))
+            (syntax-ppss (point)))
+          (expect calls :to-be-truthy)
+          (expect (< (caar calls) prompt-start) :to-be-truthy)
+          (expect (cl-third (car calls)) :to-equal prompt-start)))))
+
+  (it "fontifies through the prompt area by default"
+    (with-temp-buffer
+      (let ((eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (save-excursion
+          (goto-char (eca-chat--content-insertion-point))
+          (eca-chat--insert "history\n"))
+        (expect eca-chat-fontify-prompt :to-be-truthy)
+        (cl-letf (((symbol-function 'font-lock-default-fontify-region)
+                   (lambda (beg end loudly)
+                     (push (list beg end loudly) calls))))
+          (eca-chat--fontify-region (point-min) (point-max))
+          (expect (nreverse calls)
+                  :to-equal (list (list (point-min) (point-max) nil)))))))
+
+  (it "can skip markdown after-change extension for prompt edits"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            markdown-called)
+        (eca-chat-mode)
+        (goto-char (eca-chat--prompt-field-start-point))
+        (cl-letf (((symbol-function 'markdown-font-lock-extend-region-function)
+                   (lambda (&rest _args)
+                     (setq markdown-called t))))
+          (run-hook-with-args 'jit-lock-after-change-extend-region-functions
+                              (point) (point) 0))
+        (expect markdown-called :to-be nil))))
+
+  (it "can skip syntax propertize for prompt-only regions"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (goto-char (eca-chat--prompt-field-start-point))
+        (insert "prompt")
+        (setq-local eca-chat--syntax-propertize-function
+                    (lambda (beg end)
+                      (push (list beg end) calls)))
+        (funcall syntax-propertize-function
+                 (eca-chat--prompt-field-start-point)
+                 (point-max))
+        (expect calls :to-be nil))))
+
+  (it "still runs syntax propertize for history regions"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (save-excursion
+          (goto-char (eca-chat--content-insertion-point))
+          (eca-chat--insert "history\n"))
+        (let ((prompt-start (eca-chat--prompt-area-start-point)))
+          (setq-local eca-chat--syntax-propertize-function
+                      (lambda (beg end)
+                        (push (list beg end) calls)))
+          (funcall syntax-propertize-function (point-min) prompt-start)
+          (expect (nreverse calls)
+                  :to-equal (list (list (point-min) prompt-start)))))))
+
+  (it "clips chat fontification before the prompt area when disabled"
+    (with-temp-buffer
+      (let ((eca-chat-fontify-prompt nil)
+            (eca--chat-init-session (make-eca--session))
+            (eca--chat-init-skip-welcome t)
+            calls)
+        (eca-chat-mode)
+        (save-excursion
+          (goto-char (eca-chat--content-insertion-point))
+          (eca-chat--insert "history\n"))
+        (let ((prompt-start (eca-chat--prompt-area-start-point)))
+          (cl-letf (((symbol-function 'font-lock-default-fontify-region)
+                     (lambda (beg end loudly)
+                       (push (list beg end loudly) calls))))
+            (eca-chat--fontify-region (point-min) (point-max))
+            (expect (nreverse calls)
+                    :to-equal (list (list (point-min) prompt-start nil)))))))))
+
 (describe "eca-chat--render-content"
   (describe "progress finished"
     (it "clears progress text and spinner when chat-loading is nil"