Files older than the feature components/text-overrides mark a copy text
with :text-content-attribute (any style) or :text-content-structure
(letters and styles). Migration 0034 compares each such copy with its
near main and gives it the groups its old flags allowed where it
differs; an old flag where nothing differs sets nothing. A copy whose
near main cannot be reached keeps every group its flags allowed, so it
loses no override. The migration adds the feature, so a client on the
old code cannot write the old groups into a migrated file.
Binfile import leaves the copies whose near main is in a library not
linked yet, as it does with swap slots, and converts them once the
libraries are linked: the deferred pass of the import now runs both
conversions (convert-deferred!, *defer-unreachable*).
Validation reports the old groups (:legacy-text-touched), and its
repair recomputes them against the near main; a text override group
without :content-group is still :invalid-text-touched. A shape with no
letters in it and its main no longer counts as differing in its styles.
Benchmark (lower quantile, ms; baseline / now / ratio):
deepest-edit-through-three-levels 35.2 / 34.8 / 0.99
edit-through-a-chain-of-dependents 68.9 / 65.0 / 0.94
library-update-into-copies 83.1 / 86.9 / 1.05
main-edit-into-10-copies 1.8 / 1.5 / 0.86
main-edit-into-100-copies 15.4 / 15.0 / 0.97
main-edit-into-1000-copies 153.1 / 150.6 / 0.98
variant-switch-into-copies 32.1 / 26.8 / 0.84
AI-assisted-by: claude-opus-5-5
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