feat(preview): update preview to use perspective and source

[cngonzalez]

Description

As we convert things to sources, we can also get rid of some complexity. There wasn't much sense in having separate preview and projection stores, at least without access to schemas. The projection store has batched querying and status coalescing and everything else we need in previews.

This PR removes the preview store and leaves some deprecated functions that pass through to the projection store to maintain backwards compatibility. The React hook uses useDocumentProjection directly, which means we can remove the deprecated functions in v3.

Some helpers were moved around and updated to prepare for this as well.

What to review

• The new preview transformation logic in previewProjectionUtils.ts
• The refactored useDocumentPreview hook implementation
• The updated e2e tests that verify preview functionality
• The kitchensink app changes that demonstrate the preview functionality

Testing

Added comprehensive unit tests for:

• transformProjectionToPreview utility
• getPreviewState function
• resolvePreview function
• useDocumentPreview hook

Also updated e2e tests in the kitchensink app to verify that preview results are displayed correctly and update in real-time when document content changes.

Fun gif

FIXES SDK-761

[vercel]

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Project	Deployment	Actions	Updated (UTC)
sdk-docs	Ready	Preview, Comment	Feb 6, 2026 4:48pm
sdk-kitchensink-react	Ready	Preview, Comment	Feb 6, 2026 4:48pm

[cngonzalez]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• refactor(presence): convert presence to use source #735
• refactor: localize not using resource on client to the client store #734
• feat(releases): update releases store to use sources #733
• feat(preview): update preview to use perspective and source #731 👈 (View in Graphite)
• feat(document): update document store to accept sources #730
• test(e2e): create e2e tests for recent source changes #728
• feat(projection): update projection store to use source and perspective #723
• test: make sign-in tests more lenient #732
• main

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[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🟢	Lines	95.37% (🎯 95%)	7803 / 8181
🟢	Statements	95.37% (🎯 95%)	7803 / 8181
🟢	Functions	95.94% (🎯 95%)	379 / 395
🟢	Branches	92.87% (🎯 90%)	2306 / 2483

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
packages/core/src/preview/getPreviewState.ts	100%	83.33%	75%	100%
packages/core/src/preview/previewProjectionUtils.ts	100%	95.65%	100%	100%
packages/core/src/preview/resolvePreview.ts	100%	100%	100%	100%
packages/core/src/projection/types.ts	0%	0%	0%	0%
packages/react/src/hooks/preview/useDocumentPreview.tsx	92.59%	66.66%	100%	92.59%	113-114

Generated in workflow #2924 for commit d32d02a by the Vitest Coverage Report Action