feat: add auto-RTL for mixed-script content in auto mode

[alinadaf]

Summary

Adds a new setting Auto-RTL for mixed LTR/RTL content (disabled by default) that, when enabled in auto mode, overrides the browser's first-strong-character heuristics for lines containing RTL scripts.

Details

Problem

When a line starts with English text but contains Arabic, Hebrew, or Persian later (e.g. Hello سلام), the browser's dir="auto" sees the first strong character (Latin) and renders the line LTR — which is incorrect.

Solution

• EditorPlugin.ts: Modified buildDecorations() to check each line for RTL characters when auto mode + setting enabled, applying dir="rtl" when found.
• MarkdownPostProcessor.ts: Added applyMixedContentRTL() that applies dir="rtl" to block elements (p, li, h1-h6, td, th, blockquote) containing RTL scripts in reading view.
• direction.util.ts: Added shared RTL_CHAR_REGEX and hasRtlChar() utility.
• settingsTab.ts: New boolean setting autoRTLForMixedContent with UI toggle.

Testing

Set default direction to Auto, enable the new setting, and type mixed LTR/RTL content in a note.

[esm7]

Hi Ali,

First, we cannot call it "auto", as "auto RTL" is the common and universal name for the "BIDI algorithm" which is exactly the default behavior: decide based on the first letter with strong directionality.

What you want is a different logic that I don't know how to call, perhaps something like "RTL-preferred auto". As it gives precedence to switching to RTL regardless of where the relevant characters are in the sentence.

However, I find this logic very uncommon and very counter-intuitive. Do you really want sentences like "I wrote a message to my friend Ali (علي), who said RTL needs to be improved" to switch to RTL? Can you explain the need, and whether you know any software that behaves like that?

[alinadaf]

Hi esm7, I’ve been using your “RTL Support” plugin in Obsidian and ran into an issue with mixed Farsi–English content. In Farsi text, we sometimes need to mix English and Farsi words within the same sentence to explain some concept—particularly when the first word can't be translated because it's something like a Git command, and the rest of the sentence explains it in Farsi. For example: """ دستورات مهم گیت: git status: وضعیت مخزن را نشان می‌دهد. git commit -m "توضیح": تغییرات را به مخزن می‌فرستد و یک Commit ایجاد می‌کند. git checkout -b <نام شاخه>: یک شاخه جدید ایجاد می‌کند و به آن می‌رود. """ When I use the "RTL Support" plugin in Obsidian with the "Default text direction" set to "Auto", these kinds of sentences consistently break and become unreadable. The issue is that although the sentence should be read right-to-left, the editor renders it left-to-right because the first word is in English. To address this, I submitted a pull request on GitHub proposing that my changes be merged into the original code. My solution introduces new logic to handle this scenario, and users can deliberately enable it through the plugin's settings.

[esm7]

Hi Ali,

Since RTL and BIDI support is a well-established doctrine, I don't want us to make up behaviors that no app ever uses.
As far as I know, your "any RTL character wins" algorithm is uncommon and not used by any software.
Let's work to find a solution to your described use case that is within well-established norms.

For example, how about we add a syntax to a block to mark it as RTL, e.g. decide that if the block opening includes # direction: rtl, it is forced RTL?
This is much more consistent with how BIDI-compatible software behaves. Lots of software, from MS Word to web apps, usually have auto, RTL or LTR, while nothing has the logic of "RTL if some character in the middle is RTL".