Scaffold-only ticket. Captures the architecture for taking the
#000061 cold-pack format and adding a second mode beside hydrate:
overlay an existing pack onto a populated shard set ("graft").
Surfaced while running the #000065 reshard cutover and fox extended
the design: each pack carries a `corpus_name` field
(wikipedia-2010, wikipedia-current, arxiv-cs, ...), making
`arborist cold graft wikipedia-current` feel like `apt install`.
Three concerns analysed:
doc/chunk/edge overlay trivial (INSERT OR IGNORE on content-
addressed PKs collapses dupes)
FTS5 overlay trivial (new chunk_ids → new fts rows)
audit chain overlay the only hard part — three approaches:
A graft receipt (chosen): one event in
host chain carrying pack_hash +
event_count + first/last hashes; pack
file is the durable witness; zero
schema cost; aligned with v8/v9
witness pattern
B re-chain everything: rejected — graft
is frequent so invalidating external
refs is wrong tradeoff (different
story from the one-time reshard)
C chain forest with chain_id col: right
answer when graft dominates lifecycle
but premature now
Long-game payoff: mesh-peer-corpus-merge. Two peers diverge over a
partition, each carries packs the other lacks, reconciliation =
exchange + graft what's missing. Makes "mesh of arborists"
coherent rather than "fleet of arborists."
Scaffold gated on (a) #000065 lands+stabilises, (b) a second
corpus exists to graft, (c) at least two peers want to exchange.
No code until then; the design lock is what the ticket buys.
Index bumped Next ID 000066→000067.
russell@unturf.com
f4397a9217