fix: use JSON.stringify for caption text escaping in generated JS

[hobostay]

Summary

• Replace manual single-quote escaping with JSON.stringify() in caption JS generation
• Manual escaping only handled backslash and single quotes, missing newlines, carriage returns, and other special characters that break generated JavaScript syntax

Details

Affected file: packages/studio/src/captions/generator.ts (lines 306-313)

A caption segment containing a literal newline (e.g. from a multiline caption) would produce broken JS like:

segVar.textContent = 'line1
line2';  // SyntaxError: Invalid or unexpected token

JSON.stringify handles all special characters correctly and produces a double-quoted string literal that is always valid JS.

Test plan

• Create captions with special characters (newlines, quotes, backslashes) and verify the generated HTML is valid
• Verify existing single-line captions still render correctly

🤖 Generated with Claude Code

[jrusso1020]

Verified — generator.ts:306 only handles \\ and ', so a caption segment with a literal newline (or a U+2028/U+2029) emits broken JS. Switching to JSON.stringify is the right call: it returns a complete double-quoted JS string literal that handles all control chars and line separators, and the surrounding quotes are correctly removed at the call sites. LGTM.

[vanceingalls]

Additive review at 49d4dbba — @jrusso1020 already verified and approved.

Audited

• packages/studio/src/captions/generator.ts:306-313 (the JSON.stringify replacement)
• CI: all required green ✓

Strength

James covered the correctness — JSON.stringify produces a complete double-quoted JS string literal that handles control chars, U+2028/U+2029, embedded quotes, and backslashes correctly. The two failure modes the old manual regex missed (literal newlines, line separators) are both fixed. ✓

Important — supersedes the caption portion of #794 and #795

Both #794 (Jefsky) and #795 (Jefsky) ship the same caption fix (JSON.stringify(seg.text)) but bundle it with broken LayersPanel.tsx new-file additions that would clobber existing code on merge. Recommend merging this single-purpose PR and closing #794 + the caption portion of #795 to keep the surface clean. I've flagged the same in those PRs.

Nit

• A positive-pin test for the contract would be small and high-value here — expect(generateCaptionJs("line1\nline2")).toContain('"line1\\nline2"') pins the JSON.stringify behavior against a future "let's roll our own escaping again" regression. Out of scope for this PR, but worth a follow-up.

Verdict

Verdict: COMMENT
Reasoning: Fix is correct (James verified); single-purpose diff, CI green. Vance check before merging — this is external-contributor code but it's the canonical one of three competing PRs for this bug. Recommend landing this and closing #794 + the caption portion of #795.

— Vai

[vanceingalls]

hobostay's caption JSON.stringify escape fix. @jrusso1020 already APPROVED on this SHA. CLEAN merge state. (Note: there's a duplicate-shape #794 from Jefsky against a broken bundle — close that one in favor of this.) Vance authorized the stamp.

Verdict: APPROVE
Reasoning: James verified, correct fix shape, CLEAN.

— Vai