Argument-0005: Retention at Rank 1

Report Date	2026-01-20
Submitted by	Timothy Wu

Member details

• Matrix username: @timwu20:matrix.org
• Polkadot address: 1RaxuqWvyd6sdAEiansxmtget47PVcsSR38d9V2uPzKu2vo
• Current rank: 1
• Date of initial induction: Seeding
• Date of last report: 2025-10-06
• Area(s) of Expertise/Interest: Consensus protocols, Networking, Availability, Parachain consensus

Reporting period

• Start date: 2025-07-05
• End date: 2025-01-20

Argument

During this reporting period, I served as Technical Team Lead for the Parity <> ChainSafe Q3/Q4 2025 engagement, a treasury-funded collaboration to contribute directly to Polkadot-SDK development. In this role, I led a team of senior engineers working closely with Parity on initiatives including speculative availability, approval checking rewards, and WebRTC transport improvements.

My individual contributions during this period include:

Polkadot SDK - Speculative Availability

Implemented speculative availability chunk requests within the Availability Distribution subsystem in PR #10563 (open, awaiting review). This feature enables nodes to fetch erasure-encoded chunks from backing groups before candidates are actually backed on-chain by:

• Listening to ActiveLeavesUpdate events and querying Prospective Parachains for backable candidates
• Moving request_backable_candidates from Provisioner to subsystem-util for shared use
• Introducing CoreInfo and CoreInfoOrigin types to distinguish between scheduled (speculative) and occupied (on-chain backed) fetch origins
• Adding AvailabilityStoreMessage::NoteBackableCandidate message type to pre-store validation metadata
• Including CLI flag --speculative-availability for feature activation
• Adding metrics tracking with origin labels on polkadot_parachain_fetched_chunks_total
• Zombienet functional test validating chunk fetching for parachains supporting elastic scaling

RFCs - Approval Checking Rewards

Authored RFC for Approval Checking Rewards in ChainSafe/RFCs PR #1 (open). This RFC proposes revisions to the Rewards RFC, specifically addressing:

• Tallies submission via signed extrinsics
• How validator points are assigned to validators based on rewards computation

Also contributed spelling and terminology fixes to the base Rewards RFC in burdges/Polkadot-RFCs PR #2 (open). Waiting for this PR to be merged before creating the upstream PR to polkadot-fellows/RFCs.

str0m - WebRTC Library Upstream Contributions

Contributed upstream to the str0m WebRTC library (dependency of litep2p):

• PR #711 (merged September 30, 2025): Restored the ability to disable DTLS fingerprint verification via RtcConfig.set_fingerprint_verification and fixed STUN username attribute decoding. This addresses issue #549 and enables litep2p's WebRTC transport to function correctly.

litep2p - WebRTC Transport Improvements

Contributed to the litep2p networking library used by Polkadot nodes:

• PR #422 (merged August 14, 2025): Updated the str0m WebRTC library dependency and refactored code to work with its breaking API changes. This update was included in litep2p v0.11.0 release.

• PR #513 (open, 2 approvals): Implementing proper graceful shutdown for WebRTC substreams by adding support for the FIN/FIN_ACK handshake protocol per libp2p spec. Key implementation details:

  • State machine flow: Open → Closing → FinSent → FinAcked
  • 5-second timeout protection to prevent indefinite waiting (matching go-libp2p)
  • Unified message variants and fixed flag handling logic
  • Closes issue #476

Summary

My contributions demonstrate expertise in:

• Availability subsystem - Speculative chunk fetching to improve parachain availability
• Networking - WebRTC transport layer improvements for litep2p
• Consensus economics - RFC work on approval checking rewards

Voting record

Provide your voting record in relation to required thresholds for your rank.

Ranks	Activity thresholds	Agreement thresholds	Member's voting activities	Comments
I	90%	N/A	I have voted on 0 out of 0 referenda in which I was eligible to vote.
II	80%	N/A
III	70%	100%
IV	60%	90%
V	50%	80%
VI	40%	70%

Misc

• Question(s):

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