@remotion/studio: Let rulers cover the full canvas

[JonnyBurger]

Summary

• let the horizontal and vertical Studio rulers cover the full inset canvas
• avoid applying the ruler width twice when sizing the ruler canvases
• add a regression test for both ruler orientations

Testing

• bun test packages/studio/src/test/canvas-rulers.test.ts
• bun run build
• bun run stylecheck
• verified in Remotion Studio

Closes #9343

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Project	Deployment	Actions	Updated (UTC)
bugs	Ready	Preview, Comment	Jul 24, 2026 8:33am
remotion	Ready	Preview, Comment	Jul 24, 2026 8:33am

[pullfrog]

Reviewed changes — fixes a double-subtraction bug where rulers were sized too small, and adds a regression test.

• Extract getRulerCanvasSize helper — the horizontal ruler now spans the full inset size.width and the vertical ruler spans the full inset size.height, instead of subtracting RULER_WIDTH a second time on top of the inset already applied by applyRulerInsetsToCanvasSize.
• Add regression test — verifies both ruler orientations use the full inset dimensions after applyRulerInsetsToCanvasSize has been applied.

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• Mode: Review (initial)
• Files reviewed: 3
• Commits reviewed: 1
• Base: main (bf0206d)
• Head: codex/fix-studio-ruler-size (b6e91fa)
• Reviewed commits:
  • b6e91fa — @remotion/studio: Let rulers cover the full canvas
• Prior pullfrog review: none
• Submitted at: 2026-07-24T00:00:00Z
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