Introduce the presentation-free RuntimeEntityDirectory and RuntimeEntityRecord as the sole owners of server GUIDs, INSTANCE_TS incarnations, accepted snapshots, authority versions, retryable tombstones, session epochs, and local-ID allocation. Convert LiveEntityRuntime into an App projection sidecar host resolved through canonical record identity without a second GUID map.
Preserve the existing synchronous and reentrant projection lifecycle, including retryable registration/delete/session teardown. Add Runtime-only identity/lifetime tests and App ownership guards.
Validated by the Release solution build and 8,441 complete Release tests with five existing skips.
Co-authored-by: Codex <codex@openai.com>
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