The prototype contains commented-out debug code, PoC-style printouts, and unused variables. Cleaning these up brings the code to production quality and makes it suitable for code review. This also includes removing the old O search code path that the augmented skiplist replaces.

Tasks

• src/block/block_ext.c — Remove all commented-out debug code: printout_skiplist, update_max_size_clone, debug printfs, assertion blocks (criterion: grep -n "^//|printf" src/block/block_ext.c returns no PoC artifacts)
• src/block/block_ext.c — Remove WT_UNUSED macros for variables that should be properly used or deleted (tmp, i, bstack, estack, ext, ext1) (criterion: no spurious WT_UNUSED in block_ext.c)
• src/block/block_ext.c, src/include/block.h — Fix indentation, spacing, and comment style per WiredTiger conventions (criterion: cd dist && ./s_all -q reports no style violations in changed files)
• src/block/block_ext.c — Replace C++ style // comments with C style /* */ (criterion: no // comments in production code paths)
• src/block/block_ext.c — Verify __block_first_srch is fully replaced or disabled; remove old O code path (criterion: no callers of the legacy function remain)

Files to create or modify

• src/block/block_ext.c — skiplist implementation
• src/include/block.h — structure definitions

Definition of Done

• All debug/PoC code removed
• Old O __block_first_srch code path removed
• Code conforms to WiredTiger C style (passes dist/s_all checks)
• No commented-out code, unused variables, or debug printfs remain