Corrects a foundational error: "handler type unchanged -> retract skipped,
process diffs" was never actually true. StoreBind unconditionally calls
Dispatch.retractUnder before every re-dispatch (already stated in the
original dispatch model doc) -- Tag's old assert(v==nil) was taken at
face value and the general rule was wrongly back-derived from it.
Tag, Ref, Slot, and Attribute (the last three designed earlier this same
session) all inherited the flawed premise. Fixes across all four:
- Tag: rewritten around kTagMap/tagNameMap reference counting so
AddTag is entirely process's job, RemoveTag entirely retract's,
using a Contains hint to skip engine calls that would be immediately
redone. Also fixes the case where two independent Tag(...) values at
different positions share a name (union semantics, like className).
- Ref/Slot: drop the incorrect assert(v==nil), split into "retract
unbinds/destroys the old, process binds/mounts the new" with an
identity check on both sides to avoid spurious re-fire.
- Attribute: AttributeKeyHandler.retract gated on v==nil so ordinary
value updates don't flicker the attribute to nil; the group's
"unchanged name" delegation now also retracts before reprocessing,
since skipping it was silently stacking chain entries every cycle.
Reversal preserved in archive/retract-always-fires-reversed.md.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
