The special discovery-index account was keyed as "@index", which the consumer's
normalizeUsername collapses to "index" — colliding with a real user named
"index" (who could then hijack/tamper the global index document). Introduce a
reserved-account namespace (a sentinel key unreachable by any typed username) so
the index account can never collide with user input. Test proves a user named
"index"/"@index" resolves to a DIFFERENT document than the reserved index
account. 80 tests pass; tsc rc=0.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Add a generic discovery-index surface: submitToIndex(ref) deposits a reference
into the index document's inbox; readIndex() returns the materialized entries. A
reserved special account (@index) owns the index document; deposits flow through
the emulated inbox and are materialized by the emulated curator (the dedup/
moderation point). This replaces cross-account fan-out as the discovery path and
is more faithful to the target (a single owned index fed via its inbox). Generic
(the consumer supplies the reference to index). 79 tests pass; tsc rc=0.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Sylvain Duchesne