Fix Flyspell: Persistent Highlights After Saving Words

Hey guys, ever been in that super productive zone, cranking out code or prose in Emacs, only to hit save word with Flyspell and watch all your beautiful red squiggly lines vanish into thin air? It's a real buzzkill, isn't it? You've got flyspell-persistent-highlight set to t, you expect those misspellings to stay highlighted, but nope, they're gone! This common Emacs quirk can be super frustrating, especially when you're trying to keep your documents spick and span. But don't worry, you're not alone, and more importantly, we're going to dive deep into why this happens and, more importantly, how to fix it so your Flyspell highlighting stays put like a good little highlight should. We'll explore everything from understanding the root cause to advanced Elisp tricks, making sure your Emacs setup is as smooth and efficient as possible. So, grab your favorite beverage, let's get your Flyspell highlights to truly persist, making your writing and coding experience much more seamless. This isn't just about a quick fix; it's about understanding and mastering your Emacs environment for peak productivity.

Understanding the Problem: Why Flyspell Highlighting Disappears

Alright, let's cut to the chase and understand why Flyspell highlighting disappears after a "save word" action, even when you've meticulously set flyspell-persistent-highlight to t. This issue often boils down to how Emacs's display engine, specifically font-lock-mode, interacts with Flyspell's re-scanning process. When you tell Flyspell to save a word, what actually happens under the hood is a series of actions: Flyspell updates its dictionary or ignore list, and then, for the change to take effect, it often re-scans the current buffer or a portion of it. This re-scan, while necessary to apply the new spelling status, can sometimes inadvertently trigger a refresh of font-lock-mode, which is responsible for all syntax highlighting, including Flyspell's. Think of font-lock-mode as the big boss of how things look in your buffer; when it refreshes, it essentially re-evaluates what should be highlighted, and sometimes, this process doesn't perfectly re-apply all the previous Flyspell highlights, especially if the re-scan isn't comprehensive or if other minor modes interfere. Even with flyspell-persistent-highlight enabled, which is designed to keep highlights around, the very act of saving a word and the subsequent buffer updates can cause a temporary flicker or a complete clearing of existing marks if the refresh mechanism isn't perfectly synchronized. It's like asking a librarian to re-shelve one book, but they end up reorganizing the entire section, and in the process, a bookmark you had placed gets lost. The intention of flyspell-persistent-highlight is to ensure that highlights don't get cleared just by moving your cursor or switching buffers, but a structural change like saving a word and initiating a re-scan is a different beast entirely. We're essentially dealing with a slight disconnect between Flyspell's internal state management and Emacs's display refreshing cycle, leading to this frustrating temporary loss of visual cues. Understanding this interplay between Flyspell's logic and Emacs's display rendering is the first crucial step to finding a robust solution. We're looking for ways to ensure that after Flyspell does its thing, the display engine is properly told to re-apply those persistent highlights without any hiccups, keeping your Emacs experience smooth and visually consistent. This phenomenon isn't a bug per se, but rather an interaction that can be optimized for a better user experience, ensuring that your save word action doesn't accidentally wipe out your visual progress. So, we're not just fixing an annoyance; we're refining how Emacs handles spell-checking feedback to make it truly reliable and unobtrusive during your workflow.

Initial Troubleshooting Steps: Checking Your Setup

Before we dive into any complex Elisp wizardry, let's start with some initial troubleshooting steps to ensure your Flyspell setup is configured correctly and to rule out any simple misconfigurations. This methodical approach can save you a lot of headache, folks, because sometimes the fix is much simpler than you think. First and foremost, you absolutely need to verify flyspell-persistent-highlight. While you mentioned it's set to t, it's always good to double-check in your current Emacs session. You can do this by typing M-x describe-variable RET flyspell-persistent-highlight RET. Make sure the value displayed is indeed t. If it's nil for some reason, that's your immediate culprit! You can set it directly by adding (setq flyspell-persistent-highlight t) to your init.el or ~/.emacs file. Next up, consider your Emacs version and Flyspell version. Emacs is constantly evolving, and sometimes these seemingly minor quirks are resolved in newer versions. Are you running the latest stable Emacs release? If not, an upgrade might mysteriously fix the issue, as newer Flyspell versions or font-lock-mode implementations could have improved their interaction. Check your Emacs version with M-x emacs-version. It's always a good idea to keep your Emacs up-to-date, not just for bug fixes but for all the fantastic new features too. Another critical area to investigate is conflicting packages. Emacs's strength lies in its extensibility, but sometimes, different minor modes or other installed packages can unintentionally interfere with Flyspell's behavior. Think about any other modes that might modify highlighting, buffer refreshing, or interact with spell checking. Are you using company-mode, ivy, helm, or any other completion frameworks that might trigger buffer refreshes? Perhaps a specific language mode has its own highlighting rules that clash? To identify potential conflicts, try running Emacs with a minimal init.el. This means starting Emacs with emacs -Q (which loads no init.el at all) and then manually enabling flyspell-mode in a test buffer. If the issue doesn't reproduce, you've narrowed it down to something in your configuration. Then, you can gradually add parts of your init.el back in until the problem reappears, pinpointing the problematic package or setting. This minimal init.el test is invaluable for debugging and helps isolate the problem faster than anything else. Trust me, many an Emacs mystery has been solved by this simple yet powerful method. Don't forget to also check for any custom advice (C-h f advise-add RET) or hooks that might be running after a save action or a buffer modification, as these could also be inadvertently clearing the highlights. A thorough check of these basic elements will often reveal the root cause or at least provide valuable clues for further investigation, setting us up nicely for more advanced solutions if these don't quite hit the mark.

Advanced Solutions: Restoring Highlights Manually or Automatically

If the basic troubleshooting steps didn't quite nail it, fear not! We're now diving into advanced solutions for restoring Flyspell highlights, focusing on both manual and automatic approaches that leverage Emacs's powerful Elisp capabilities. The most immediate, though inconvenient, fix is simply re-running flyspell-buffer. After you save a word and notice the highlights disappear, executing M-x flyspell-buffer RET will force Flyspell to re-scan and re-highlight the entire buffer. This confirms that Flyspell can highlight the buffer correctly, it's just not doing it automatically after the save action. While effective, doing this manually every time is a productivity killer, right? So, let's automate it! This is where Emacs hooks come into play, offering a brilliant way to trigger actions automatically after specific events. One powerful hook you could consider is after-save-hook. This hook runs every time you save a buffer. You could add a function to this hook that re-runs flyspell-buffer. A simple example would be: (add-hook 'after-save-hook #'flyspell-buffer). However, be cautious with this! flyspell-buffer can be resource-intensive on very large files, and you might not want it running after every single save. A more nuanced approach might involve using post-command-hook, but with conditions. This hook runs after every command, which is even more frequent, so you'd need to write a custom function that checks if the last command was flyspell-correct-word (or flyspell-word or flyspell-correct-at-point) and only then re-applies highlighting. This requires a bit more Elisp know-how, but it gives you finer control. For instance, you could define a function like this:

(defun my-flyspell-rehighlight-after-save-word ()
  "Re-highlight buffer with flyspell after saving a word."
  (when (eq last-command 'flyspell-correct-word)
    (flyspell-buffer)))
(add-hook 'post-command-hook #'my-flyspell-rehighlight-after-save-word)

This is a basic example and might need refinement depending on the exact Flyspell function you use to save words. You might also want to explore if flyspell-mode offers its own, more specific hooks. While flyspell-post-save-word-hook isn't a standard Emacs hook, you could potentially advise (using C-h f advise-add) the flyspell-correct-word function to run flyspell-buffer after its original execution. This is a more advanced technique but very powerful for injecting custom behavior into existing functions without rewriting them. Leveraging font-lock-mode interaction is also key here. Sometimes, simply telling font-lock-mode to re-highlight the current region can be enough. (font-lock-flush) followed by (font-lock-ensure) can sometimes force a re-evaluation of the current buffer's highlighting. Combining these with a conditional hook or advice could provide a very robust solution. Another angle is to use timer functions or idle-timer to re-scan the buffer after a short delay, ensuring that all underlying processes have settled before re-applying the highlights. This can prevent race conditions where Flyspell's re-scan might clear highlights before font-lock has a chance to properly render the persistent ones. The goal here is to find the right balance between responsiveness and thoroughness, ensuring that your Emacs doesn't feel sluggish while still providing those persistent, helpful spell-check highlights. Experiment with these different Emacs Elisp approaches, guys, and you'll find the custom function or auto-highlighting hook that perfectly fits your workflow, making your Flyspell experience truly seamless.

Community Wisdom and Best Practices

When you're dealing with Emacs, especially with these nuanced interactions between modes, tapping into community wisdom is often one of the quickest ways to find solutions or at least gain deeper insights. Seriously, guys, the Emacs community is incredibly active and helpful! If the previous steps haven't fully resolved your persistent highlighting woes, consider seeking advice on Emacs forums like r/emacs on Reddit, the GNU Emacs mailing lists, or Emacs-specific sections on Stack Exchange. When you post for help, remember to emphasize reproducible steps. This is absolutely crucial! Clearly describe what you're doing, what you expect to happen, and what actually happens. Include your Emacs version, OS, and the relevant parts of your init.el (especially anything related to Flyspell, font-lock-mode, or hooks). A minimal example that demonstrates the issue (using emacs -Q as a starting point) is gold for anyone trying to help you. Think of it as providing a clear map to your problem, making it easier for others to navigate and offer solutions. Beyond specific fixes, there are also some general tips for a smooth Emacs experience with Flyspell. Always try to keep your Emacs and installed packages updated. Package managers like straight.el or package.el make this incredibly easy. Updates often include bug fixes and performance improvements that can quietly resolve issues you might not even know you have. Also, regularly review your init.el for any redundant or conflicting settings. Sometimes, old configurations can linger and cause unexpected behavior with newer Emacs versions or packages. Keep your configuration clean and modular; use use-package for organizing your configurations, as it helps prevent conflicts and makes your init.el much more readable and maintainable. If you're experimenting with custom Elisp code, ensure it's robust and handles potential errors gracefully. Using (condition-case ERR ...) blocks can prevent minor errors in your custom functions from crashing your entire Emacs session. Remember that debugging Flyspell issues often involves looking at messages in the *Messages* buffer (check C-h e) and understanding how font-lock interacts with minor modes. Sometimes, the problem might not be with Flyspell itself, but how another mode is refreshing or interfering with the buffer's display properties. By following these Emacs community best practices, not only will you increase your chances of finding a solution, but you'll also contribute to the collective knowledge base, helping others who might encounter similar problems down the line. It's all about collaborative problem-solving in the wonderful world of Emacs, ensuring everyone has the most efficient and enjoyable text-editing environment possible. Don't be shy about asking questions; that's how we all learn and grow within this amazing ecosystem.

Conclusion

So, there you have it, folks! We've journeyed through the sometimes-tricky world of Flyspell's persistent highlighting in Emacs, covering everything from understanding why highlights disappear to implementing advanced Elisp solutions. The key takeaway here is that while Flyspell aims for persistence, the dynamic nature of Emacs's display engine and various buffer actions can sometimes cause temporary visual hiccups. But with a bit of understanding and the right configuration, you can absolutely get those red squigglies to stay put after a "save word" action. We talked about verifying flyspell-persistent-highlight, checking for conflicting packages, and the power of a minimal init.el for debugging. Then, we dove into more sophisticated Emacs Elisp techniques, like using hooks and advising functions to automatically trigger re-highlighting, ensuring that your Emacs productivity remains at its peak. Remember, the Emacs community is a treasure trove of knowledge, so don't hesitate to reach out if you hit a wall, always providing clear, reproducible steps. By combining careful configuration, a bit of Elisp magic, and community collaboration, you can ensure your spell-checking feedback is not only accurate but also visually consistent, making your writing and coding experience in Emacs as seamless and enjoyable as possible. Keep experimenting with these Flyspell summary tips, tailor them to your specific needs, and truly master your Emacs environment. Happy Emacs-ing!