#4679 — composite catch-up guard + unskip fixture (root cause fixed in JasperFx.Events 2.9.0)

[jeremydmiller]

Closes #4679.

Root cause

The reporter's instinct — that composite projections were the trigger — was exactly right. Composite projection member stages built their shard names as:

var shardName = new ShardName(projection.Name, ShardName.All, projection.Version); // store-global — tenant dropped

Under catchUpPerTenantAsync (per-tenant event partitioning), each tenant iteration rebuilt the same store-global member progression row, so the second tenant's InsertProjectionProgress (SequenceFloor 0) violated pk_mt_event_progression → 23505 on the bare :All identity. That matches the report exactly: every global :All shard, failing once the loop hits a second tenant.

Fix (already shipped upstream)

jasperfx#419 changed composite ProjectionStage to compose member shard names with the parent's tenant id:

var shardName = ShardName.Compose(projection.Name, tenantId: parent.TenantId, version: projection.Version);

(its fix comment names marten#4679 as the root cause). This shipped in JasperFx.Events 2.9.0 and is already referenced by Marten — now 2.9.1. So #4679 is resolved for anyone on Marten 9.7.0 / JasperFx.Events ≥ 2.9.0; the report was on 2.8.2.

This PR

• Sharded/Bug_4679_sharded_catch_up_23505 — adds a multi-stage CompositeProjectionFor catch-up guard (3 tenants on one shard) asserting that both the composite's own shard (…Composite:All:tenant) and every member stage (…:All:tenant) write tenant-scoped progression rows. This exercises the exact path Revisit Event Type Registration #419 corrected; it would have failed pre-2.9.0.
• Regressions/Bug_4679_catch_up_per_tenant_23505 — unskipped (the fix is in the referenced JasperFx.Events). This single-DB SingleStream repro never triggered the 23505 on its own — the real trigger was composite projections — but it stays as a per-tenant catch-up advance + no-23505 guard.

All three Bug_4679 tests pass against JasperFx.Events 2.9.1.

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