Week 45 · 2026

Highlights

Five PRs merged this week, increasing Head capacity, fixing snapshot and persistence stalls, and improving the documentation. Four further PRs opened. There was no new Hydra release during the reporting period.

Ecosystem Support (M4). The snapshot capacity increase merged Monday, raising the maximum from 4,095 to 32,767 outputs in response to a builder's request. It uses a larger trusted setup from the Ethereum KZG ceremony. The limit includes outputs owed by pending commits and decommits alongside the Head's UTxO set. The setup switch is marked as a breaking change for the next release.

Operational Excellence (M3). The capacity stall fix merged Friday, closing #2924. Previously, a transaction could push the Head over its accumulator limit and trigger a snapshot request that every party rejected, leaving further snapshots blocked. Snapshot construction now reserves capacity for pending commits and decommits, defers deposits that do not fit, and rejects expanding decommits that depend on unconfirmed merges. TxValid still reports local ledger acceptance; confirmation comes with inclusion in a snapshot.

The SQLite and startup improvements also landed. Event writes are split into batches of at most 1,000, fixing a deadlock when a batch exceeded the bounded write queue. Startup skips unnecessary event replay and streams required history in bounded batches, reducing the amount held in memory. Test filtering now fails when it selects no tests, preventing a misleading successful result.

Maintenance and DevX (M5). The transaction guide now explains why Plutus transactions inside a Head need collateral even when fees are zero, resolving the reported NoCollateralInputs issue. Collateral must come from the Head's own UTxO set; a suitable spending input can also serve as collateral. The contributor guide was refreshed with current binary caches, a faster edit-and-test workflow, and the checks needed before submitting changes.

Next. All four PRs opened this week remained open on 8 November. The transaction payload cleanup would release pruned transaction bodies while allowing pending snapshots to recover missing payloads through retransmission. A separate snapshot stall report reproduces a transaction expiring between local acceptance and snapshot processing; that issue remained open at the week's end.

The user-defined policies proposal would let builders constrain deposits, minting, allowed assets and UTxO count, with every participant required to use the same policy. This follows the request for application-level validation in #2913.

A draft HeadLogic refactor explores composing state machines with Crem and separating protocol decisions from their execution through an interpreter. The accompanying review guide connects the rules to generated diagrams, reproducible traces and compatibility tests, making snapshot, deposit and recovery behaviour easier to inspect. The draft retains existing network and persistence formats; performance costs and recovery policies remain part of the review. Work also opened on the documentation publishing workflow.