chore: message parser limit on the client

[gabriellsh]

Proposed changes (including videos or screenshots)

This PR is a complementary of #40306. On this PR we are making consistent the behavior between the BE and FE regarding message parsing, with the use of the new MESSAGE_MAX_PARSE_LENGTH environment variable.

Issue(s)

CORE-2211

Steps to test or reproduce

1. Setup: Run Rocket.Chat with the MESSAGE_MAX_PARSE_LENGTH environment variable set to 100.

2. Under Limit: Send a message with < 100 characters containing markdown (e.g., Hello **bold**). Verify the markdown renders correctly. In the database, the message must contain the md property.

3. Over Limit: Send a message with > 100 characters containing markdown. Verify it renders as plain text (raw asterisks).

4. Contexts: Verify the same behavior (under vs. over limit) inside a Thread and when Quoting/Replying.

5. Editing: Edit a short message (currently rendered) and add text to exceed 100 characters. Verify it loses markdown formatting upon saving.

6. Translations: Enable Auto Translate in a room (Administration > Settings > Message > Auto Translate — requires a translation service configured as per the Auto Translate documentation). Set the target language and send a message in a different language with > 100 characters containing markdown. Verify that the message renders as plain text using the translated text, not the original source language. Also verify the "Translated" indicator is still shown. Repeat inside a Thread parent preview and when Quoting/Replying.

7. Disabled State: Re-run Rocket.Chat with the MESSAGE_MAX_PARSE_LENGTH env var set to 0. Verify that every message now render markdown correctly again (0 means disabled).

Further comments

[dionisio-bot]

Looks like this PR is not ready to merge, because of the following issues:

• This PR is missing the 'stat: QA assured' label
• This PR is targeting the wrong base branch. It should target 8.6.0, but it targets 8.5.0

Please fix the issues and try again

If you have any trouble, please check the PR guidelines

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Latest commit: cc9a123

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[codecov]

Codecov Report

❌ Patch coverage is 94.75524% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.58%. Comparing base (cedda23) to head (cc9a123).
⚠️ Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #40600      +/-   ##
===========================================
- Coverage    69.80%   69.58%   -0.23%     
===========================================
  Files         3325     3330       +5     
  Lines       122974   125254    +2280     
  Branches     21943    21922      -21     
===========================================
+ Hits         85839    87153    +1314     
- Misses       33784    34795    +1011     
+ Partials      3351     3306      -45     

Flag	Coverage Δ
unit	69.76% <95.07%> (-0.75%)	⬇️

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[Copilot]

Pull request overview

This PR aligns the client-side rendering/parsing behavior with the server’s new MESSAGE_MAX_PARSE_LENGTH setting by skipping markdown parsing when message text exceeds the configured limit, falling back to plain-text rendering.

Changes:

• Add client-side limit resolution (rc-message-parser-max-length meta) and caching utilities (getPageMeta, getMarkdownParserLimit).
• Enforce the limit in key parsing/rendering paths (parseMessageTextToAstMarkdown, normalizeThreadMessage, MarkdownText, omnichannel contact history).
• Add unit tests covering limit behavior across parsing and UI components.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
apps/meteor/client/views/omnichannel/contactHistory/MessageList/ContactHistoryMessage.tsx	Render plain message.msg when md is absent (e.g., parsing skipped).
apps/meteor/client/lib/parseMessageTextToAstMarkdown.ts	Skip parsing and return a plain-text AST when text exceeds the configured limit.
apps/meteor/client/lib/parseMessageTextToAstMarkdown.spec.ts	Add tests for “over limit” plain-text AST behavior (message + attachments).
apps/meteor/client/lib/normalizeThreadMessage.tsx	Apply the parser limit to thread preview normalization, falling back to plain-text tokens.
apps/meteor/client/lib/normalizeThreadMessage.spec.tsx	Add tests validating “within limit” vs “over limit” behavior and error handling.
apps/meteor/client/lib/getPageMeta.ts	Add meta tag reader with in-memory caching.
apps/meteor/client/lib/getPageMeta.spec.ts	Add tests for meta reading and caching behavior.
apps/meteor/client/lib/getMarkdownParserLimit.ts	Resolve the markdown parser limit from meta/default constant with “0 disables” semantics.
apps/meteor/client/lib/getMarkdownParserLimit.spec.ts	Add tests for limit resolution from meta/default constant.
apps/meteor/client/components/message/content/attachments/QuoteAttachment.tsx	Adjust quote rendering fallback when md is missing (but introduces a regression risk).
apps/meteor/client/components/MarkdownTextInner.tsx	Extract previous MarkdownText parsing/sanitization implementation into an inner component.
apps/meteor/client/components/MarkdownText.tsx	Add limit-based early return to render plain text without parsing.
apps/meteor/client/components/MarkdownText.spec.tsx	Add tests for limit-based plain-text vs parsed rendering.

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