contentHash was left empty on every capture; hashReferencedElsewhere returns
false for empty hashes, so every remove looked like a last reference. Add
FNV-1a hashBytes to capture_paths, wire into both commit paths. NOTE: this
activates index dedup-by-hash in production — a bit-identical re-capture now
collapses onto the existing entry instead of adding a duplicate (spec-intended).
Timer-driven realtime capture behind ICaptureBackend (begin/tick/abort via
OnTimer, non-blocking). Records master into a hidden temp track, moved to the
bank non-destructively with idempotent restore across every terminal path.
Pure phase machine unit-tested. Track/item deferred; realtime is non-deterministic.
daniel