libs/game/coedit (zero deps, so merge logic is testable without a socket or
a VM). Not a CRDT: transactions are host-serialized into an append-only
generation history, and a conflict is answered by handing the author the new
base so THEY re-derive their intent.
- Transaction carries the author's whole intended file, not a patch: the
diff against its declared base is derived host-side, so a stale or
malformed patch can never be applied — and an AI writes whole files anyway
- diff3 over lines with LCS anchors. Merge::Conflict deliberately carries NO
merged text: a half-merged game file that still parses is worse than an
honest rejection. Conflict -> Rebase{new base + per-generation summary of
what landed underneath}. An edit already present in the tip is refused as
NoChange rather than appended as an empty generation
- Leases are advisory as designed: a test asserts a submit SUCCEEDS while
another author holds the lease. They shape who chooses to edit; they never
gate the log. TTL expiry means a crashed author cannot lock a region
- Wire: coedit is reliable-channel ONLY — a test signs a valid submission,
sends it by datagram, and asserts it is ignored, so no datagram can
rewrite the game. Every response is addressed, never broadcast
- Arcade bridge routes in exactly one place; local agent and remote authors
share the queue and the rules, and a test asserts the local agent gets
rebased identically when it loses a race. Remote players map to
AuthorId(player+1) so a client holding player id 0 cannot impersonate the
host's agent
- 200-round deterministic fuzz: 4 authors submit against deliberately stale
bases, rebase, resubmit — asserting linear append-only numbering, no
generation claiming a base from the future, and that replaying accepted
diffs from generation 0 reproduces the head exactly
Two real bugs found building it: validate used `?` on the base lookup, so an
unknown base returned "no refusal" instead of UnknownBase; and
MAX_COEDIT_SOURCE (512 KiB) exceeded MAX_FRAME_BYTES (256 KiB), so the host
would have accepted a source it could never hand back inside a Rebase,
stranding the next author on an answer that never arrives. Both now 192 KiB.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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