docs(relayBench): note the NIP-62/09/40 sync-fairness gap in effectiveEvents

The harness's reconcile reference only collapses replaceable kinds; it ignores
NIP-62 Request to Vanish, NIP-09 deletions, and NIP-40 expiration. So a
compliant relay (geode, which honors NIP-62) is falsely flagged "did not
converge" and the phantom events inflate its reconcile round count, masking
negentropy speedups at the wire. Documents the symptom (traced to one
ALL_RELAYS vanish pubkey in the damus corpus), the census (7 vanish pubkeys,
381 expiry events, 0 deletions in the first 200k), and the fix design for
whoever implements it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012EZeWww5TJnzBZKPoc6mvU

relayBench/plans/2026-07-04-sync-fairness-nip62-09-40.md

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+# relayBench sync fairness: account for NIP-62 / NIP-09 / NIP-40
+
+**Status: note / not yet implemented.** Captures a measurement bug found while
+validating the negentropy work, so the next person doesn't re-derive it.
+
+## The problem
+
+`SyncBenchmark.effectiveEvents` builds the "reference" set the harness
+reconciles against by collapsing **replaceable/addressable** kinds to their
+newest version — and nothing else. But a spec-compliant relay stores strictly
+*less* than that, because it also honors:
+
+- **NIP-62 Request to Vanish** (kind 62). A `["relay","ALL_RELAYS"]` (or
+  this-relay) vanish request means the relay deletes **all** events from that
+  pubkey. geode implements this (`RightToVanishModule`); strfry does not.
+- **NIP-09 deletions** (kind 5). Both geode and strfry apply these, but the
+  harness reference keeps the deleted events *and* the deletion.
+- **NIP-40 expiration** (`expiration` tag). geode drops expired events; strfry's
+  support differs.
+
+So the harness reference over-counts: it retains events a compliant relay is
+*required* to have removed.
+
+## The symptom
+
+The sync pair is flagged **"did not converge ✗"** even when the relays are
+behaving correctly. In the 1M-corpus run this showed as geode "missing" 28
+events vs the reference — all traced to a **single NIP-62 vanish pubkey**
+(`fa0778c1ccbb…`, `["relay","ALL_RELAYS"]`): geode correctly purged that user's
+31 events, strfry kept them, and the harness expected them present.
+
+Two concrete distortions:
+
+1. **False non-convergence.** `converged` (SyncBenchmark ~line 273) compares
+   the relays' stored sets to the unfiltered reference, so a NIP-62/40-compliant
+   relay can never converge against a corpus that contains vanish/expiry events.
+2. **Inflated reconcile cost.** The identical-set reconcile uses the unfiltered
+   `effective` as the *initiator's local set*. Those phantom events are real
+   leaves negentropy must hunt, so geode's steady-state reconcile ran **3 rounds
+   / ~520 ms** instead of the **1 round / ~110 ms** it would take against a
+   matching set — which masks negentropy speedups (v1.1.1/v1.2.0) at the wire
+   behind the extra round-trips.
+
+## The census (first 200k of the damus 1M corpus)
+
+- NIP-62 vanish requests: **7 distinct pubkeys**
+- NIP-09 deletions: **0**
+- NIP-40 expiration-tagged events: **381**
+
+## The fix (when someone picks this up)
+
+Make the reference model what a compliant relay actually stores, in
+`effectiveEvents` (or a new `compliantEffective`):
+
+1. Collect vanish pubkeys (kind 62); drop every event from them, and the vanish
+   request itself, whose `created_at` is at/under the vanish request's time (or
+   unconditionally for `ALL_RELAYS`).
+2. Apply kind-5 deletions: drop referenced `e`/`a` targets authored by the same
+   pubkey.
+3. Drop events whose `expiration` tag is in the past (needs a fixed "now").
+
+Then a compliant relay (geode) converges cleanly, and a relay that ignores these
+NIPs (strfry) is correctly flagged as retaining events it should have dropped —
+which is the honest comparison, not a geode penalty. The steady-state reconcile
+also becomes a real 1-round measurement, so negentropy improvements show at the
+wire.
+
+Until then, a clean wire-level sync measurement needs a **pre-filtered corpus**
+(drop vanish-pubkey events + expiry-tagged events); see the geode↔geode run that
+accompanies this note.