[nstepien]

vp pack compiles src/ with React Compiler, which skips every component or hook it can't compile. On main, it skips DataGrid, EditCell, GroupedRow, useCalculatedColumns, useColumnWidths, and useViewportRows. After this PR, all of them are compiled, and if a bail-out comes back, oxlint reports it and vp pack fails in CI.

Unsupported syntax

• useColumnWidths: replace ||= with an if statement. hasChanges = hasChanges || … would trip eslint/logical-assignment-operators.
• useCalculatedColumns / useViewportRows: replace x++ on variables captured by nested functions with x += 1.
• Enable react/todo, which reports both. It was turned off in oxlint: configure react rules #4155, before React Compiler was set up, while the generators couldn't be compiled either. Replace iterateOverViewportColumnsForRow with mapViewportColumns, and fix cells hidden by colSpan #4225 removed them.

Immutability

• GroupedRow: let idx was incremented in the mapViewportColumns callback when the first rendered column was the select column, and GroupCell compared it with column.idx. The group-by columns follow the select column in groupBy order, so GroupedRow now compares each column's key with groupBy[row.level] and passes the result to GroupCell as isLevelMatching.

Hoisted functions

• DataGrid: the useImperativeHandle callback read setPosition, which is declared further down. The handle now exposes setPositionLatest, which also keeps its setActivePosition stable across renders, and the react/immutability suppression is gone.
• EditCell: the useLayoutEffect cleanup called cancelTask, which was declared after the effect. It moves to module scope and takes the two refs: declared in the component, it would have to be an effect dependency, and the effect must not clean up between re-renders, as the comment there explains. onClose also moves above the useEffectEvent that calls it. The TODO: report React Compiler bug note and its react/invariant suppression are gone.

Build

• compiler: { reportDiagnostics: true } turns the code React Compiler skips into plugin warnings. vp pack already fails on warnings in CI and agent sessions (failOnWarn: isAgent || 'ci-only'), and vp dev, vp build, and vp test log them. Unlike lint, a suppression comment doesn't hide them. panicThreshold: 'all_errors' would fail every build, including the dev server and tests while code is being edited, and 'critical_errors' misses unsupported syntax like x++.
• One react() instance now serves both Vite and vp pack. It produces identical lib/ and website builds, and the same dev-server modules. vp pack can't use lazyPlugins, so its plugins were already created on every config load. The plugin keeps some per-run state, like whether to emit development JSX, which is fine because Vite and vp pack never run in the same process.
• .d.ts files stay excluded: vp pack passes the declaration files it generates through the plugin, and without the exclusion, lib/index.d.ts becomes export {}, which publint doesn't catch. node_modules stays excluded too, as setting exclude replaces the plugin's default.
• AGENTS.md mentions that vp pack fails on code React Compiler can't compile.

vp run ci passes.

🤖 Generated with Claude Code

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.13%. Comparing base (5ffecb4) to head (ec1fa41).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4162      +/-   ##
==========================================
+ Coverage   98.96%   99.13%   +0.16%     
==========================================
  Files          46       46              
  Lines        2030     2186     +156     
  Branches      792      961     +169     
==========================================
+ Hits         2009     2167     +158     
+ Misses         21       19       -2     

Files with missing lines	Coverage Δ
src/DataGrid.tsx	99.06% <100.00%> (+0.17%)	⬆️
src/EditCell.tsx	98.88% <100.00%> (+1.74%)	⬆️
src/GroupCell.tsx	100.00% <ø> (ø)
src/GroupedRow.tsx	100.00% <100.00%> (ø)
src/hooks/useCalculatedColumns.ts	100.00% <100.00%> (ø)
src/hooks/useColumnWidths.ts	98.68% <100.00%> (+0.05%)	⬆️
src/hooks/useViewportRows.ts	100.00% <100.00%> (+1.63%)	⬆️

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