Adversarial review (standards#145) of the storage/migration surface found four
real defects, all data-integrity. All confirmed against the code and fixed; no
false positives.
BLOCKER - concurrent save race. saveChannelMessages / saveMessages are
read-modify-write with an await gap, so two saves to the same key raced and the
second clobbered the first, silently losing messages (e.g. a message and its
delivery ack arriving together). BlobStore now provides synchronized(key, ...),
a per-key operation chain; every RMW - merge-save, remove, and the load-path
legacy migration - runs through it. Different keys stay concurrent. New test
fires two concurrent saves and asserts the union survives.
BLOCKER - non-atomic DB relocation. The documents->support move copied and
deleted each file (.sqlite/-wal/-shm) in turn, so a failure after the main file
moved stranded the DB across two locations and corrupted it. Now copies all
files, verifies each by size, and only then deletes the sources; on any failure
it rolls back the destination and leaves the original intact.
MAJOR - load-path legacy migration raced save. The #194 index->PSK adoption did
a blind write to the PSK key that could clobber a save that landed first. It now
runs under the key lock and MERGES (union) instead of overwriting, so both the
adopted history and any fresh message survive.
MINOR - channel merge key lacked a sender. Two senders posting identical text at
the same timestamp without a messageId would collide and lose one. The key now
includes the sender, matching MessageStore.
flutter analyze clean, dart format clean, 509 tests pass. Full Gemini log in
docs/llm-consultations/.
Strycher
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