fix(emcn): keep Prism grammar registrations in bundle, never throw on missing grammar

[waleedlatif1]

Summary

• Selecting files in the start block's input format (file[] field) crashed immediately with The language "json" has no grammar. — and the same crash was latent in every other workflow-editor code highlighter (subflow editor, condition input, code blocks, tool-input editor, variables JSON editor).
• Root cause: consumers import { highlight, languages } from the @sim/emcn barrel, which re-exported Prism's highlight straight from prismjs. Bundlers resolved that passthrough directly from prismjs and skipped prism.ts's module body — dropping the side-effect grammar registrations, so languages.json (etc.) were undefined at runtime and Prism threw.
• Fix is centralized at the source: prism.ts now owns highlight as a local wrapper, so the grammar registrations stay in the dependency graph, and the wrapper degrades to escaped plaintext when a grammar is missing instead of throwing.
• No per-file imports or inline guards — one change covers all consumers.

Type of Change

• Bug fix

Testing

Tested manually — start-block file[] field and other workflow-editor editors no longer crash; tsc clean across @sim/emcn and apps/sim.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Jun 30, 2026 8:05pm

[cursor]

PR Summary

Low Risk
Localized UI syntax-highlighting fix with a defensive fallback; no auth, data, or API surface changes beyond safer highlighting behavior.

Overview
Fixes workflow-editor crashes (The language "json" has no grammar.) by changing how highlight is exported from prism.ts.

Instead of re-exporting Prism’s highlight from prismjs, the module now defines a local highlight wrapper that calls prismHighlight internally. That keeps the side-effect grammar component imports in the bundle graph when consumers pull { highlight, languages } from the @sim/emcn barrel—bundlers no longer resolve highlight straight from prismjs and drop the registrations.

The wrapper also falls back to HTML-escaped plaintext when grammar is undefined, so a missing or unregistered language degrades safely instead of throwing. All barrel consumers get this behavior from one centralized change.

^{Reviewed by Cursor Bugbot for commit abc3c74. Configure here.}

[greptile-apps]

Greptile Summary

This PR centralizes Prism highlighting in the EMCN code helper.

• Adds a local highlight wrapper around Prism.
• Keeps grammar registration imports in the same module as the exported helper.
• Falls back to escaped plaintext when a grammar is missing.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The wrapper preserves the existing exported names.
• The missing-grammar fallback returns escaped text in the inspected rendering path.

Important Files Changed

Filename	Overview
packages/emcn/src/components/code/prism.ts	Replaces the direct Prism highlight re-export with a local wrapper and missing-grammar plaintext fallback.

_{Reviews (1): Last reviewed commit: "fix(emcn): keep Prism grammar registrati..." | Re-trigger Greptile}