Runtime upgrade to 2207: completing slot-based Aura consensus migration (phase 3 of 3)

This motion authorizes the enactment of runtime-2207 on Astar mainnet. It completes the slot-based Aura consensus migration that began with runtime-2204 by aligning the relay parent offset enforcement in runtime validation. This is phase 3 of 3 of the migration.

The runtime also freezes new WASM (ink!) contract uploads and instantiation as the first step of a broader WASM smart-contract sunset on Astar. Existing WASM contracts continue to execute, hold state, and accept calls normally; user funds remain in user wallets and are not affected by this change.

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Forum post (consensus migration): Runtime 2204 upgrade: migrating Astar to slot-based Aura consensus for improved fork resistance in block production

Full changelog: runtime-2207 release notes

Required client version: Astar binary v5.49.2

Operational prerequisite (collator action required)

This runtime requires Astar collator client v5.49.2 or later. Any collator still running the legacy lookahead client at the time of activation will produce invalid candidates, stop authoring blocks, and risk being removed from the active collator set.

Collator operators have been notified via direct channels and through the runtime-2204 and runtime-2206 motion descriptions. Activation of runtime-2207 should be coordinated with confirmed binary migration across the active set, verified via telemetry and the collatorSelection pallet authorship data.

What changes in runtime-2207

Aligns the relay parent offset to 1 in runtime validation. Closes the slot-based Aura consensus migration. After activation, incoming parachain candidates must carry a relay parent at R minus 1 with one descendant; non-conformant candidates are rejected at the runtime layer. This is the enforcement step that delivers the full fork-resistance benefit at the collator authoring layer.
Freezes new WASM (ink!) contract uploads and instantiation. First step of the WASM smart-contract sunset (rationale and plan below). Existing deployed WASM contracts continue to execute and respond to calls. EVM contracts, EVM precompiles, and direct extrinsic interactions are unaffected.

Three-phase rollout (closing the consensus migration)

The slot-based Aura migration is sequenced across three onchain governance events. This motion enacts the final phase.

Phase 1: runtime-2204 (enacted). Exposed RelayParentOffsetApi and GetCoreSelectorApi, with the relay parent offset held at 0.
Phase 2: runtime-2206 (enacted). Set the relay parent offset to 1 for block production in soft mode, without runtime enforcement.
Phase 3: runtime-2207 (this motion). Activates runtime validation of the relay parent offset and descendants. Closes the migration window.

WASM contract freeze

The freeze is the first step of a broader WASM smart-contract sunset on Astar and Shiden. Rationale:

pallet_contracts is upstream legacy and the ink! language has been discontinued by its maintainers. Continuing to support new WASM deployments commits Astar to long-term maintenance of a stack with no upstream future.
Onchain WASM contract activity on Astar and Shiden is minimal, with effectively no live consumer dApps.
Freezing new deployments now reduces the WASM surface area while existing state is preserved during the offboarding window.

This motion enacts the freeze only. Existing WASM contracts continue to execute and respond to calls; no migration is required, and user funds in user wallets are unaffected. Subsequent steps of the sunset (deployer outreach, eventual pallet removal on Shiden and Astar, storage-deposit returns) will be detailed in a dedicated forum post and proposed as separate governance actions.

Expected impact

Consensus migration fully active: slot-based collators benefit from reduced fork-induced reorgs across the active set; remaining wall-clock variance reflects relay-chain inclusion latency only.
Approximately 6 seconds of additional latency on incoming XCM messages (outgoing XCM unaffected).
Negligible reduction in usable proof-of-validity space due to descendant headers carried in each parachain block.
No new WASM (ink!) contracts can be uploaded or instantiated on Astar mainnet after activation. Existing WASM contracts continue to execute normally. User funds in user wallets are unaffected.

Risk considerations

Collator operators still running the legacy lookahead client at activation will produce invalid candidates and stop authoring blocks. Mitigation: confirmed binary migration of the active set via telemetry and onchain authorship data prior to enactment.
Builders intending to deploy or instantiate new WASM contracts on Astar will need to adjust their plans. Existing WASM contracts are unaffected. Identifiable WASM deployers will be contacted directly as part of the sunset process described in the forthcoming forum post.

Action requested

Approve enactment of runtime-2207 on Astar mainnet: completing the slot-based Aura consensus migration (phase 3 of 3) and initiating the first step of the WASM smart-contract sunset.