Add ProjectIndexer (project_lib, QtConcurrent + QFutureWatcher, 6 tests):
runs listFiles/listSymbols on the thread pool, delivers results on the UI
thread via filesReady/symbolsReady, caches per project root, and drops
stale results via a per-root generation counter.
Switchers now open the palette immediately — cache hit is instant, miss
shows a transient 'Indexing…' placeholder — and repopulate when the
background job finishes. The ~0.5-1s ctags stall on Alt+G no longer
blocks the UI thread. Cache invalidated on KateProjectBridge::
projectChanged. Register QList<Symbol> metatype; link Qt6::Concurrent.
Item building factored into buildFileItems/buildSymbolItems (shared by
the cache and async paths).
Add a benchmark harness (src/project/bench_switcher.cpp, manual target)
that times the Go-to-File/Symbol pipeline against a real project and
writes a metrics file. Measured on mobydick (12.2k files, 17.2k symbols);
findings in docs/PERF.md.
Bottleneck: PaletteModel::setQuery re-scored all N every keystroke
(Debug: 270-600ms/keystroke; cost grew with query length). Fix: when the
query is a pure append, re-score only the currently-visible subset — the
match set is monotonic under appending, so this is exact. Later keystrokes
drop from O(N) to O(matches) (symbols 'server' 30ms -> 9ms in Release).
Guarded by test_palettemodel::incrementalMatchesFullScan.
Also documented: shipped plugin is a Debug build (~5-8x slower than
Release), and ctags/listFiles run ~0.1-1s synchronously on open (move
off-thread = open follow-up).
Levi Neely