`MollifierBuffer.ack` previously deleted the entry hash. It now sets
`materialised=true` and resets the TTL to a 30s grace window via a new
atomic `ackMollifierEntry` Lua script. The entry hash persists past
materialisation as a read-fallback safety net for the brief PG replica
lag window between drainer-side write and reader-side visibility (Q1
D2).
`BufferEntrySchema` gains an optional `materialised` boolean (string
"true"/"false" in Redis → boolean in JS). Accept still refuses while
*any* entry exists for the runId — including materialised ones — as
defense-in-depth against runId reuse.
The drainer's "drains one queued entry … and acks" test now asserts
`materialised=true` instead of entry deletion. The "re-accept after
ack works" test is inverted to "accept refused while a previously-acked
entry is still inside its grace TTL".
Dan Sutton
22dbbc90fa