#20286: Matrix: render LaTeX for Element Desktop by emitting data-mx-maths in formatted_body

## Summary - Problem: Matrix messages containing LaTeX (`.........`, `.........`) were sent as plain Markdown HTML (`<p>.........</p>`), which Element does not render as math. - Why it matters: Users see raw LaTeX text instead of rendered equations, making math-heavy chats difficult to read. Element is the most used and feature-riched client for Matrix. - What changed: Updated `extensions/matrix/src/matrix/send/formatting.ts` to detect inline/block LaTeX and emit Element-compatible `data-mx-maths` markup in `formatted_body`. - What did NOT change (scope boundary): No changes to non-math Markdown rendering behavior, no protocol-level Matrix API changes, no config schema changes. ## Change Type (select all) - [x] Bug fix - [ ] Feature - [ ] Refactor - [ ] Docs - [ ] Security hardening - [ ] Chore/infra ## Scope (select all touched areas) - [ ] Gateway / orchestration - [ ] Skills / tool execution - [ ] Auth / tokens - [ ] Memory / storage - [x] Integrations - [ ] API / contracts - [x] UI / DX - [ ] CI/CD / infra ## Linked Issue/PR - Closes #20276 ## User-visible / Behavior Changes - Matrix messages containing LaTeX now render in Element when sent by OpenClaw: - Inline math: `$$x^2$$` → `<span data-mx-maths="x^2"><code>x^2</code></span>` - Display math: `E=mc2E = mc^2E=mc2` → `<div data-mx-maths="E = mc^2"><code>E = mc^2</code></div>` - Non-math messages are unchanged. ## Security Impact (required) - New permissions/capabilities? (`No`) - Secrets/tokens handling changed? (`No`) - New/changed network calls? (`No`) - Command/tool execution surface changed? (`No`) - Data access scope changed? (`No`) ## Repro + Verification ### Environment - OS: Ubuntu 24.04.4 LTS - Runtime/container: OpenClaw gateway local runtime - Model/provider: ChatGPT Codex 5.3 - Integration/channel (if any): Matrix (Element Desktop) - Relevant config (redacted): Matrix plugin enabled; standard `org.matrix.custom.html` message formatting path ### Steps 1. Send a Matrix message via OpenClaw containing `E=mc2E = mc^2E=mc2`. 2. Inspect sent event `content.formatted_body`. 3. Open message in Element Desktop and verify rendering. 4. Repeat for inline example `$$x^2$$` embedded in normal text. ### Expected - `formatted_body` contains `data-mx-maths` markup for detected math. - Element renders equations as math, not raw `$` delimiters. ### Actual - Before fix: `formatted_body` contained `<p>E=mc2E = mc^2E=mc2</p>` (raw text shown in Element). - After fix: `formatted_body` contains `data-mx-maths` HTML and renders correctly. ## Evidence Attach at least one: - [ ] Failing test/log before + passing after - [x] Trace/log snippets - [] Screenshot/recording - [ ] Perf numbers (if relevant) ## Human Verification (required) What you personally verified (not just CI), and how: - Verified scenarios: - Display math-only message renders in Element. - Inline math in mixed text renders. - Normal non-math markdown remains unchanged. - Edge cases checked: - Multiple math expressions in one message. - Multiline display-math capture with `.........`. - What you did **not** verify: - Full escaped-dollar edge cases (e.g. `\$`) across all clients. - Behavior in non-Element Matrix clients. ## Compatibility / Migration - Backward compatible? (`Yes`) - Config/env changes? (`No`) - Migration needed? (`No`) ## Failure Recovery (if this breaks) - How to disable/revert this change quickly: - Revert commit affecting `extensions/matrix/src/matrix/send/formatting.ts`. - Files/config to restore: - `extensions/matrix/src/matrix/send/formatting.ts` - Known bad symptoms reviewers should watch for: - Raw placeholders like `OC_MATH_BLOCK_*` appearing in chat. - Missing or malformed `formatted_body`. - Regressions in non-math markdown formatting. ## Risks and Mitigations List only real risks for this PR. Add/remove entries as needed. If none, write `None`. None <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR adds LaTeX math rendering support for Matrix messages in Element by detecting `$...$` (inline) and `$$...$$` (block) delimiters and converting them to Element-compatible `data-mx-maths` HTML markup. The implementation uses a placeholder-based approach: math expressions are extracted before markdown rendering, then re-injected as proper HTML elements afterward. - **Critical: Inline math regex false-positives on currency text.** The pattern `\$([^\n$]+?)\$` will match text like `$10 and $20` as a single math expression, corrupting non-math messages. This needs word-boundary guards (e.g. `(?<!\w)\$...\$(?!\w)`) to avoid treating dollar amounts as LaTeX delimiters. - **No test coverage** for the new `extractMath`/`injectMath` logic — the existing test file only covers `markdownToMatrixHtml`. Given the regex edge cases, tests are important for confidence in this change. - The overall architecture (extract → render markdown → inject) is reasonable and the `escapeHtml` usage correctly prevents injection in the `data-mx-maths` attribute. <h3>Confidence Score: 2/5</h3> - The inline math regex will corrupt messages containing dollar amounts, which is a common real-world scenario - Score of 2 reflects that while the approach is architecturally sound, the inline math regex has a confirmed false-positive bug with currency text (e.g. "$10 and $20" gets treated as math). This would corrupt normal messages in production. Additionally, there are no tests for the new logic. - `extensions/matrix/src/matrix/send/formatting.ts` — the inline math regex at line 51 needs word-boundary guards to prevent false positives on currency text _{Last reviewed commit: 3e845bd} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->