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Sylpheed/docs
Sylpheed RE agent 55bfcc77d3 re: tag_hash verified disc-wide; record keys follow a stronger own-name rule
Swept all 33 dat paks plus hidden/DefTables.pak: 7,750 IDXD objects, 190,782
records, 1,271,462 (name -> tag) pairs, 0 failures, 0 parse failures.

The key rule is stronger than first written: a record's key is tag_hash of its
own inline name, 190,782/190,782 -- no roster needed (roster-based recovery only
reaches ~30% of records). Verified independently here on UnitGroup_S02, 112/112.

The modulus is uniquely pinned, not just consistent: gcd of
poly256(name) - (tag & 0xFFFFFF) over all pairs is exactly 0x00FFFFDF, prime.

Case-sensitivity is load-bearing, not incidental: the disc has 17 name pairs
differing only in case (UNIT/Unit, TYPE/Type, STAGE/Stage, ...); name_hash
collides on all 17, tag_hash separates all 17.

Records the limit too: IXUD, the wide-string sibling, uses a DIFFERENT low-24
hash (0/19,808) though it keeps the same top-byte checksum (19,808/19,808). Its
offsets are counted in 16-bit chars (STR + 2*strsize == filesize) -- newly
decoded, all 534 parse. Its low bits are provably not a modular polynomial (gcd
= 1; exhaustive Barrett search over M in [2^20,2^25) finds nothing; fixed-position
deltas are non-constant), so it is lossy and needs the XEX.
2026-08-25 11:08:10 +00:00
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