The clone command hardcoded a 10-minute context deadline with no way to raise or disable it, and the deadline did not reliably interrupt a slow clone.

- RepoCloneCmd gains a --timeout flag (default 10m, matching the old behavior; 0 disables the deadline for very large repositories). cloneContext branches away from context.WithTimeout for a non-positive timeout -- WithTimeout(parent, 0) yields an already-expired deadline, which would abort instantly the very clone the flag exists to unbound.

- The whole-repository crosslink sweep now observes context cancellation. It runs after the exchange-round loop, so it had no round boundary of its own at which the deadline could fire -- on a large repository it could run long past the deadline uninterrupted. manifest.CrosslinkContext checks the context every 256 candidates; manifest.Crosslink stays a background-context wrapper so its ~30 existing callers are unchanged. processResponse gains the same batched check so a large single-round batch is interruptible too, and the sync session's and the serve handler's post-convergence sweeps are wired to their contexts for the same reason.

Each cancellation point is pinned by a test that fails without it: the crosslink and processResponse tests drive a context that survives the first poll and dies before the second, so only the batched check can observe it; the crosslink-sweep test cancels after a zero-card final round, so nothing before the sweep is left to notice.

Also adds a clone -> serve -> reclone fidelity regression guard (#114), built with the canonical fossil binary rather than this library's Commit. Commit does not deltify, so a corpus built through it holds zero delta rows and never reaches the serve side's deltified-row expansion branch -- a green result from such a corpus proves nothing about #114. The guard now asserts the source holds delta rows before measuring anything, and compares the second-generation clone's tip, artifact count, blob-store size, delta-row count and checked-out tree content against the source.

Measured against that corpus (71 artifacts, 54 delta rows), #114 does not reproduce: gen1 and gen2 both hold the same 54 delta rows, the same tip and artifact count, a 1.009 store ratio, identical checked-out content, and pass fossil test-integrity. The receive path re-deltifies what the serve side expanded, via content.Deltify on the crosslink mlink path, so the expansion the serve side performs does not survive into the store. check-in: a02c9572da user: [email protected] tags: trunk