The cycle/self-embed/depth guard (PAGE_EMBED_MAX_DEPTH=5) lives only on the
client and is the sole protection against runaway nested rendering — and was
untested. Extract the inline predicates into pure, behavior-identical exported
helpers (isPageEmbedCycle, isPageEmbedTooDeep in the ancestry context;
filterPageEmbedOptions in the picker) so they're unit-testable without mounting
the heavy Tiptap NodeView, and add vitest coverage (20 tests): ancestry chain/
host accumulation, cycle (ancestor-in-chain + top-level self-embed), too-deep at
the cap, and picker host-exclusion.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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