Argument-0005 Retention at Rank 3

Report Date	Date of submission (2025/12/08)
Submitted by	Andrei Sandu

Member details

• Matrix username: @sandreim:parity.io
• Polkadot address: 13QdJvnJgfoitjrxESwrCWTaLMN8KvXxufDUucXM6EWGuxqh
• Current rank: 3
• Date of initial induction: 2023/07/18
• Date of last report: 2025/06/09
• Area(s) of Expertise/Interest: Parachain Consensus, Node Performance Engineering, Observability, Stress and integration testing

Reporting period

• Start date: 2025/06/10
• End date: 2025/12/08

Argument

My primary objective during this period was to enhance the Polkadot Web3 application user experience by enabling faster and more reliable block times. Initially, I concentrated on the deployment of Elastic Scaling on Polkadot. In the latter half of the period, I developed a strategy to improve parachain block production reliability and delivered a few improvements in 2025. My contributions also included code supporting the investigation of block confidence issues and enhancements to the collator protocol's reliability.

Elastic Scaling: Launch

Elastic Scaling was launched on the Polkadot RC in Sep 2025 after a series of consensus issues linked to the new V2 CandidateReceipt. The most recent issue resulted in a 30-minute block production stall on Kusama, highlighting a long-standing bug. I published the postmortem on the forum and created the fix, tests, the 1.6.2 release (Polkadot), 1.7.1 (Kusama), and the referendums to patch the networks.

I worked on releasing the collator-side support for Elastic Scaling in the 2509 stable release. I implemented docs updates, a CI runtime upgrade test, a small fix for 500ms blocks, and ran long-duration tests.

Elastic Scaling: Community Support

I provided direct assistance to the Peaq team to optimize their maximum Transaction Per Second (TPS) on their 500ms blocks testnet setup: PRs.

Improved Parachain Block Production Reliability

I started this project by creating the plan to improve block confidence in 2025 and 2026. Block confidence is defined as the ratio of finalized to produced blocks. The goal is to increase transaction in-block status confidence, which is critical for low-latency Web3 applications.

I worked with my team to deploy the Kusama Canary parachain, which provided logs to analyze and identify the top issues affecting block confidence.

I improved collator connectivity with a pre-connect mechanism implemented in #9929, #10305, #10446, as well as observability improvements in #9417 and #9844.

Polkadot advocacy

I actively participated in the Polkadot Builder Party:

• Gave a talk on the scalability of the Polkadot Cloud.
• Developed an on-chain tic-tac-toe game for a live demonstration at the event. This showcased the improved user experience enabled by shorter block times (500ms blocks). The game backend is available in this PR and the frontend code in this repository.

Voting record

Ranks	Activity thresholds	Agreement thresholds	Member's voting activities	Comments
III	70%	100%	100%	58 out of the 58

Misc

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