Render LaTeX equations with KaTeX in Content

[3mdistal]

Summary

• render canonical inline and block LaTeX with KaTeX in editable documents and read-only/public readers
• render equations in standalone HTML and PDF-ready exports while preserving canonical source in Markdown
• keep malformed equations visible and repairable, with KaTeX trust disabled and accessible MathML output
• document the syntax for agents and add a Content changelog entry
• cover rendering, security, editing, copy/paste, export, and NFM round-trips

Why

Content already parses inline $...$ and block $$ delimiters into structured NFM atoms, but those atoms were displayed as plain labels. This completes the presentation and export layers without changing the canonical source format or adding a second math grammar.

Validation

• 225 focused Vitest tests passed across math rendering, exports, NFM, editor interactions, and the public route
• production Content build passed and bundles KaTeX for client and server rendering
• frozen lockfile install and diff checks passed
• independent real-Chrome QA passed inline, display, malformed-source fallback, terminal-caret editing with refresh persistence, accessibility exposure, and narrow-viewport math overflow
• repository-wide typecheck still reports 152 pre-existing errors; none reference changed files

Notes

The local-file page actions menu does not expose HTML/PDF export, so export output is covered by focused integration tests rather than manual download QA.

[github-actions]

Visual recap — generation failed

The visual recap could not be generated for this pull request. This is informational only and does not block the PR.

Diagnostic:

No plan URL: create-visual-recap failed 422 Unprocessable Entity: {"error":"Could not parse expression with acorn"}

Agent output: Authored recap-source.json for PR #2131. It includes the full file map, editor/error wireframes, rendering-flow diagram, and five key-code review tabs. --- ⠀ 🟢 Visual Recap source is ready for CI’s deterministic publisher. stderr: Reading additional input from stdin... 2026-07-14T21:59:55.281064Z ERROR codex_core::session::session: failed to load skill /home/runner/work/agent-native/agent-native/.agents/skills/agent-native-toolkit/SKILL.md: missing YAML frontmatter delimited by ---

[builder-io-integration]

Builder reviewed your changes and found 2 potential issues 🟡

Review Details

Incremental Code Review Summary

The latest commit addresses both previously reported issues: MathRenderer now emits KaTeX markup during render for SSR/first paint, and the export parser protects inline math/code spans with collision-resistant placeholders so surrounding emphasis and links remain parseable. I resolved both prior review threads after verifying those changes in the latest diff. KaTeX remains configured with trust: false, accessible HTML+MathML output, bounded expansion, and visible malformed-source fallbacks.

New Findings

• 🟡 MEDIUM — The placeholder scanner still tokenizes escaped $/backtick delimiters as real math or code syntax, so explicitly escaped literal examples can be transformed in HTML/PDF exports.
• 🟡 MEDIUM — Display-math parsing is only handled by the top-level line walker; indented block equations under list items or nested structures can be emitted as sibling blocks and lose document structure.

This remains a standard-risk change affecting shared editor rendering and export behavior. The dev server is healthy, but browser executors again lacked navigation/DOM/screenshot tools; no live visual cases could be verified. Static/unit coverage exists for the main rendering and export paths, but not for these two new edge cases.

🧪 Browser testing: Could not verify — browser automation tools were unavailable in the executor environment; all planned cases were reported as environment-blocked.