Route all non-markdown code highlighting through the off-main-thread Shiki
worker, removing react-syntax-highlighter and prismjs entirely.
- Extend the worker with highlightLines: tokenize a whole block once and return
per-line inner HTML, so per-line layouts (diffs, gutters, virtualization) make
one worker call instead of one highlighter per line.
- Add shared WorkerHighlightedCode (whole-block) and useWorkerHighlightedLines
(per-line) primitives. Colors resolve via the --md-syntax-* CSS variables, so
theme changes never re-highlight.
- Migrate all 12 react-syntax-highlighter call sites: PermissionCard,
ToolPart, ContextSidebarTab, ToolOutputDialog (whole block) and
DiffPreview/WritePreview (per line).
- Migrate VirtualizedCodeBlock off prismjs to the worker, keeping virtua
virtualization; whole-block tokenization also restores cross-line syntax
context that per-line highlighting lost.
- Drop react-syntax-highlighter (+types) from ui and web, prismjs (+types) from
ui, and the orphaned create-element type shim.
Bohdan Triapitsyn
e41e5bac91