The JSONL append merge driver sorted timestamped entries by (0, ts) with no
further tiebreaker. Equal-ts entries then fell back to stable-sort insertion
order (base, ours, theirs), but git assigns the local side to "ours", so two
machines resolving the same conflict emitted equal-ts lines in opposite order.
The merged files diverged and never converged. gstack-telemetry-log uses
second-granularity timestamps, so same-ts collisions are routine.
Add the line content as the final sort tiebreaker so the order is total and
side-independent. Add a regression test that runs the driver with the two
sides swapped and asserts identical output.
Jayesh Betala