* fix(filer): bound retained reader cache buffers by bytes
* test(filer): keep in-flight downloads during cache trimming
* feat(mem): expose pooled allocation capacity for byte reservations
* fix(mount): share a configurable reader buffer budget across files
* fix(filer): release failed prefetch slots and memory reservations
* feat(mount): expose a soft Go runtime memory limit
* docs(filer): restore shared-download rationale in startCaching
The one-line comment replacing the original context.Background() explanation was too thin for readChunkAt to cross-reference shared resource semantics. Restore a concise note on why request cancellation must not abort a download shared by concurrent readers.
* test(filer): loosen reader cache test deadlines to 5s
Three tests used 1-second deadlines that can flake on CI under load:
TestReaderCacheBudgetInFlight, TestReaderCacheEvictionDoesNotHoldCacheLock,
and TestReaderCacheFailedPrefetchReleasesBudget. Increase to 5 seconds.
* test(filer): cover re-read after reader cache eviction
Add TestReaderCacheReReadAfterEviction: reads chunk 'a', reads chunk 'b'
(evicting 'a' via budget pressure), then re-reads 'a' and asserts a
fresh download returns correct data. Verifies the core correctness
property that eviction never exposes missing or stale data to readers.
Chris Lu