🐛 Transform every pending op by each fixup op

[alecgibson]

Fixes #717

At the moment, when the server acknowledges an op carrying fixup ops, Doc._opAcknowledged() loops over pendingOps with an inner index j, but indexes the array with i — the outer loop variable, which enumerates the fixup ops instead.

Since transformX() mutates both of its arguments in place, this isn't a harmless redundant pass. We transform pendingOps[0] once per pending op rather than once, and never transform pendingOps[1] onwards at all, so the client and the server end up disagreeing about the order of the remaining pending ops. Worse, if there are more fixup ops than pending ops, we hand undefined to transformX(), which throws a TypeError that escapes all the way out of Connection.handleMessage().

The existing tests all miss this, since they have at most one fixup op and one pending op, where i and j are both always 0.

This change indexes pendingOps with the inner loop variable, and renames both variables to fixupIndex and pendingIndex so the two can't be confused again. The equivalent loop in Doc._handleOp() was already correct.

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

[coveralls]

coverage: 97.467%. remained the same — fix-fixup-transforms-wrong-pending-op into master