A licence that repeats vault keys no longer sends an empty InsertKeys, --cdm-only no longer logs "Cached N Keys to 0/0 Vaults", and a key two tracks both licensed counts once.
Map each KID to its fragments from the ciphertext moov/moof (tenc, seig, ISM duration clock) and decode up to three windows per KID that never cross into another KID, so a clear lead cannot hide a wrong key and only the failing KID is flagged. Decode every frame (wrong-key HEVC keyframes decode clean), re-judge mid-GOP starts on keyframes, time out every FFmpeg run, and refuse to store a flagged pair again in SQLite.
The licence response lists KIDs a server vault supplied, the client proves them with the decode check, and a bad pair goes to the new session keys/bad route so the server flags its own row. Client vault keys go first over --remote, and the dashboard health warns when no SQLite vault can store flags.
Verify a vault-sourced key with an FFmpeg decode after decryption. On failure flag the KID:KEY locally with its source, restore the ciphertext, and retry through the remaining vaults and then the CDM.
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