fix(files): allowlist the schemes a markdown link may target

[waleedlatif1]

Summary

• normalizeLinkHref rejected only file for a scheme:// target and returned every other scheme unchanged. scheme:// is well-formed for any scheme, so a blocklist can't be complete here — switched it to an allowlist of http(s), ftp(s), mailto, tel.
• The rendered anchor for a linked image is built from a node attribute rather than a link mark, so the editor's own URI validation never inspects it. That made this function the step deciding whether such a target reaches the DOM.
• Committing an edit whose target normalizes away no longer unsets the link. The edit field is seeded with the current href, so committing an untouched one used to delete a link the user had only opened; refusing a target isn't the same instruction as removing one. Clearing the field still removes the link.
• Collapsed the scheme check to a single regex and dropped the now-unused one, matching how the other rules in the file are written.

Type of Change

• Bug fix

Testing

• Added coverage for the slash-bearing and unknown-scheme cases, a property test over the paddings and interior whitespace a browser strips before resolving a scheme, a test that a linked image's target is refused before it can become an anchor, and tests for all three applyLink outcomes. Each was verified to fail against the previous behavior.
• Confirmed no effect on stored documents: normalization runs on the render and edit paths only, never on parse or serialize, so a refused target still round-trips byte-identical. Verified across 21 schemes.
• Relative, anchor, protocol-relative, bare-domain, and host:port handling are unchanged, as are sim: mention links, which take a different branch.
• bun run type-check, bun run lint and the full bun run check:audits (33 audits) pass; 770 tests in the affected area pass.

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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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Aug 23, 2026 11:57am

[cursor]

PR Summary

Medium Risk
Touches XSS-relevant href sanitization in the markdown editor. The change is a tightening of existing checks with tests, not a new auth or data path.

Overview
Closes a hole in normalizeLinkHref: scheme:// was treated as a network URL and only file was blocked, so javascript://… and unknown schemes could still become clickable anchors (including linked images, whose href lives on a node attr, not a link mark).

Schemes are now allowlisted (http(s), ftp(s), mailto, tel). Everything else is dropped to '' so callers render inert text. Relative, hash, protocol-relative, and host:port handling is unchanged.

applyLink no longer unsets the mark when a non-empty target normalizes away — refusing an unsafe href is not the same as clearing the field. Tests cover slash-bearing/unknown schemes, whitespace smuggling, linked-image targets, and the three applyLink outcomes. Normalization still does not rewrite stored markdown.

^{Reviewed by Cursor Bugbot for commit 383c010. Configure here.}

[greptile-apps]

Greptile Summary

This PR replaces markdown link scheme blocklisting with an explicit allowlist and distinguishes clearing a link from refusing an unsafe target.

• Allows only HTTP(S), FTP(S), mailto:, and tel: explicit schemes while preserving relative, protocol-relative, and host-port handling.
• Prevents refused linked-image targets from becoming anchors.
• Keeps an existing link unchanged when an untouched nonempty target is refused, while explicit clearing still removes it.
• Adds normalization, linked-image, round-trip, and link-editing outcome coverage.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete blocking or independently actionable non-blocking issues identified.

The allowlist closes the unsafe explicit-scheme path across the known render and editing callers, and the revised edit behavior preserves links only when a refused nonempty target is submitted while explicit clearing continues to remove them.

Important Files Changed

Filename	Overview
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/markdown-fidelity.ts	Replaces permissive explicit-scheme handling with a focused safe-scheme allowlist while retaining established relative and bare-host behavior.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/menus/link-editing.tsx	Separates explicit link removal from rejection of a nonempty unsafe target so opening and committing an unchanged refused link does not delete it.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/menus/link-editing.test.ts	Covers setting, clearing, and refusing links through the shared applyLink helper.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/round-trip.test.ts	Expands coverage for unknown and executable schemes, browser-normalized whitespace variants, and linked-image target sanitization.

_{Reviews (1): Last reviewed commit: "fix(files): allowlist the schemes a mark..." | Re-trigger Greptile}