The live Yjs document materializes the editor-schema default `indent: 0` on
every paragraph/heading (and on the paragraph inside every list item, callout,
and table cell), but a body re-imported from git — parsed from clean markdown —
carries no indent attribute. So every live block's merge key differed from the
same block coming back from git: the three-way merge could anchor on nothing,
and the trailing unit that git's export already contained (but the merge could
not match against the byte-identical live tail) was re-appended on every
reconcile cycle. Each grown export then diverged from the last-pushed base by one
more unit — a self-sustaining, unbounded whole-body duplication loop with no
client connected.
The prior fix (0c7b73f7) excluded the volatile block `id` from the key, which
was necessary but not sufficient: `indent: 0` is a CONTENT attribute the editor
stamps as a default, so it was never stripped. Normalize editor-materialized
schema defaults (`indent: 0`) out of the block key — only the default value, so a
genuine `indent: 2` still diffs and lands — so a live block compares equal to its
git-round-tripped twin and the resync is a true no-op.
Regression test (yjs-body-merge.idempotency.spec.ts) encodes the invariant on a
body of byte-identical units (heading + paragraph + callout + table with empty
cells): a live fragment carrying indent:0 + ids merged against the git-derived
fragment (neither) with a stale-by-one base applies 0 ops and does not grow — RED
before, GREEN after.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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