perf(syntax): optimize viewport highlighting

[seatedro]

Summary

• cache syntax source text plus parsed trees instead of full-file token spans
• highlight only requested viewport byte ranges for syntax tiles
• refresh affected RenderDoc style runs instead of rebuilding the whole document per tile
• add timing logs around syntax source cache, parse, annotation, and total load time

Validation

• direnv exec . cargo check
• direnv exec . env XDG_DATA_HOME=/tmp/diffy-empty-data cargo test -p phosphor
• direnv exec . cargo test syntax_refresh_updates_only_targeted_line_runs

[capy-ai]

Added 1 comment

[capy-ai]

[🟡 Medium] [🔵 Bug]

The new cache stores both text and ParsedSyntax, but eviction sizing only counts TextStore bytes. That means actual resident memory can significantly exceed SOURCE_BYTE_BUDGET, especially for large files where tree-sitter trees are substantial, causing avoidable memory pressure and reducing the effectiveness of the LRU policy. Include parsed-tree size (or add a conservative overhead when parsed.is_some()) in entry accounting so eviction tracks true footprint.

// src/apprt/services.rs
let bytes = estimated_text_store_bytes(&source.text).max(1);
...
parsed: Option<Arc<phosphor::ParsedSyntax>>,