## Summary
- Rewrite serial background indexing to concurrent dispatch (up to
`stateless_worker_count / 2` parallel tasks)
- Add depth-counted pause/resume mechanism: completion and
signature-help handlers pause new index dispatches to prioritize user
requests
- Report indexing progress via LSP `$/progress` notifications
(percentage + file count)
- Lower thread scheduling priority (`nice +10`) for index tasks in
stateless workers via RAII `ScopedNice` guard
## Test plan
- [x] `pixi run format` — no changes
- [x] `pixi run unit-test Debug` — 551 passed, 9 skipped (pre-existing)
- [x] `pixi run smoke-test Debug` — 2/2 passed
- [x] `pixi run integration-test Debug` — 121 passed, 3 failed (all
pre-existing on main: header_context x2, staleness x1)
- [ ] Manual test: open a large project (e.g. LLVM), verify progress bar
appears and completion remains responsive during indexing
🤖 Generated with [Claude Code](https://claude.com/claude-code)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **New Features**
* Pause/resume controls for background indexing
* Concurrent, adaptive background indexing with configurable concurrency
* LSP progress reporting (create/begin/report/end) and updated
completion metrics
* **Behavior Change**
* Code completion and signature help temporarily pause indexing for
responsiveness
* Background indexing runs with reduced scheduling priority on
non-Windows and logs "files dispatched" at finish
* **Tests**
* Test client fixture defaults init options and sets workspace cache dir
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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