## Summary
- Replace flat `CompilationContext { directory, arguments }` with a
three-layer abstraction: `ResolvedFlags` (file-independent flags) →
`CompileCommand` (+ source file) → `to_argv()` (full argv on demand)
- `ResolvedFlags.flags` never contains source file path or
`-main-file-name`, making it directly usable as a clean cache key input
(e.g. PCH sharing across files with identical preambles)
- `to_argv()` handles `-main-file-name` insertion for cc1 mode
automatically — consumers no longer need to search/replace in the
argument list
- Eliminates the pollute-then-clean anti-pattern in `lookup()` and the
manual source-file replacement in `fill_header_context_args()`
## Test plan
- [x] `pixi run format` — no changes
- [x] `pixi run unit-test` — 481 passed
- [x] `pixi run integration-test` — 113 passed
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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## Summary by CodeRabbit
* **Refactor**
* Unified compile-command handling across the server and tools for more
consistent argument and flag behavior (driver vs frontend modes).
* **New Features**
* Added an LRU-backed in-memory cache to improve performance and
eviction control.
* **Chores**
* Added an option to control injection of resource-directory flags
(enabled by default).
* **Tests**
* Updated unit and integration tests to adopt the new command
representation and verify cache behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
2bbdf6c02b