The Node driver sends {field: /re/} as a BSON regex element (type 0x0B),
which the matcher previously only handled via the $regex operator form;
and dot paths with numeric segments (tags.0) were ignored because array
descent only recursed into embedded docs. Both are part of standard
MongoDB query semantics and were caught by the driver e2e suite.
server: unbounded Io async limit so the accept loop never wedges, and
treat header-read failures (client RST on pool teardown) as clean
disconnects. With the default cpu_count-1 limit, groupAsync's eager
fallback ran connection handlers inline on the accept-loop fiber once
that many connections were alive, stalling accept() and timing out
handshakes for further clients.
Add tests/e2e/: official driver CRUD, concurrency, and kill -9 recovery
suites (29 + 2 + 3 checks), plus unit tests for the query fixes.
The original dispatch restructure placed the unlock defers inside switch
prongs, where Zig runs them when the prong block exits — immediately after
acquisition. All commands therefore ran with no lock at all, which the new
stress test caught deterministically (two writers inside Engine.insert at
once). Lock acquisition now happens in the prongs and the command body runs
via dispatch_impl, so the defers (still prong-scoped) release the lock only
after the command finishes.
