ci(abi-gate): cover OutboxDiscovery and bump the asc-contracts pin

[DylanVerstraete]

Relayer twin of creditcoin3 #1316. asc-contracts #38 merged OutboxDiscovery with the automatic timelock (a4d05d7); our ABI drift gate was pinned at e300c166, main @ 2026-08-17 — before the contract existed.

What this adds

IOutboxDiscovery mirrored in write-ability (only the surface we read), asserted against the compiled artifact:

Events (5) — OutboxRegistered, OutboxRemovalScheduled, DefaultOutboxChangeScheduled, PendingDefaultCancelled, PendingRemovalCancelled
Reads (6) — defaultOutbox(uint32), activeOutboxes(uint32), isActiveOutbox, defaultDeployer(), pendingDefaultOutbox, pendingRemovalTime

A moved topic0 silently blinds a subscription, and the timelock events are our only advance notice before a default changes or an Outbox is removed. A moved selector makes a read revert with empty returndata, which the registry-first resolver cannot distinguish from "no Outbox for this chain key" — it would resolve to nothing and idle.

Notes captured in doc comments

• effectiveTime is a unix timestamp, not a block number. Our listeners are block-indexed, so there is a conversion to write.
• activeOutboxes() filters an Outbox out the moment its scheduled removal time passes, before cleanup runs. Membership disappearing is not the signal to stop watching one — we drain on our own in-flight state.

Deliberately not asserted

activeOutboxCount — present in the revision of #38 I reviewed, dropped before merge.

Pre-existing assertion unaffected

OutboxDeployer.outboxOf(uint32) still exists at a4d05d7, so the existing RegistryResolver assertion passes on the new pin. Separately (not this PR): outboxOf is a per-deployer mapping, and the confirmed cross-generation truth is OutboxDiscovery.defaultOutbox — that is the resolver rescope for #50, which this mirror now makes possible.

Verification

Gate run in strict mode (ABI_GATE_STRICT=1) against a fresh npx hardhat compile of a4d05d7: passes. cargo test --workspace 171 pass / 0 fail, clippy -D warnings clean, fmt clean, ci.yml parses, pinned SHA verified to resolve to the #38 merge commit on main.

https://claude.ai/code/session_01Kv6y52MHgtgkWmnJhdXbHB

[cursor]

PR Summary

Low Risk
Adds ABI bindings and CI drift checks only; no relayer runtime or resolver behavior changes in this diff.

Overview
Aligns the Solidity↔Rust ABI drift gate with asc-contracts #38 by pinning CI’s asc-contracts checkout to a4d05d7 (post–OutboxDiscovery + automatic timelock) instead of the pre-#38 commit.

Adds IOutboxDiscovery to write-ability — a hand-maintained sol! mirror of the registry surface the relayer will read: five timelock/registration events and six view calls (defaultOutbox, activeOutboxes, isActiveOutbox, defaultDeployer, pendingDefaultOutbox, pendingRemovalTime). Doc comments note that effectiveTime is a unix timestamp and that activeOutboxes membership alone is not a reliable “stop watching” signal.

Extends abi_surface tests to assert every mirrored event topic0 and function selector against OutboxDiscovery.json from compiled artifacts (same strict CI path as other contracts). OutboxDeployer.outboxOf assertions stay; comments point default resolution at defaultOutbox for a future resolver change. activeOutboxCount is intentionally not pinned (dropped before #38 merged).

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