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fix: checkpoint block-shape and block-count validation gaps - #25229

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spl/fix/checkpoint-block-shape-validation
Aug 14, 2026
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fix: checkpoint block-shape and block-count validation gaps#25229
spalladino merged 1 commit into
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spl/fix/checkpoint-block-shape-validation

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@spalladino spalladino commented Aug 14, 2026

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Fixes two independent validation gaps around checkpoint shape.

1. A zero-tx block after the first in a checkpoint

There is no circuit for proving a non-first block with zero transactions. The zero-tx block-root circuit (rollup_block_root_first_empty_tx) exists only so that an epoch can be proven when there are no transactions at all, and it is pinned to index 0: it starts a fresh sponge blob and carries a non-zero in_hash, both of which the block-merge continuity checks forbid at any later index.

Validation methods had upper bounds on block contents but no lower bound, so a checkpoint carrying an empty block past the first would pass every node-side check and then be unprovable.

Fix: validateCheckpointStructure now requires every block after the first to carry at least one tx, and the sequencer floors minValidTxs at 1 for any block past index 0 so it never builds one. The archiver passes allowEmptyNonFirstBlocks on the L1-ingest path, since such a checkpoint is already final on L1 and refusing to ingest it would only stall sync.

2. Block-count ceiling in network config

Network configuration allowed maxBlocksPerCheckpoint to be set higher than the attestable limit, which would produce block indices that p2p and checkpoint validation reject. It is now capped at MAX_ATTESTABLE_BLOCKS_PER_CHECKPOINT.

Fixes A-1614

A checkpoint can only be proven if every block past the first carries at least one tx: the only
block-root circuit that handles a zero-tx block is pinned to index 0. Checkpoint validation now
enforces that lower bound, the sequencer floors minValidTxs at 1 past the first block, and the
archiver opts out of the rule so L1 ingest never stalls on a checkpoint that is already final.

Also caps maxBlocksPerCheckpoint at MAX_ATTESTABLE_BLOCKS_PER_CHECKPOINT in network consensus
config validation, so a network cannot be configured with a block geometry whose later block
indices its own nodes would reject.
@github-actions github-actions Bot added the port-to-next Forward-port this merged PR into next label Aug 14, 2026
@spalladino spalladino removed the port-to-next Forward-port this merged PR into next label Aug 14, 2026
@spalladino
spalladino enabled auto-merge (squash) August 14, 2026 14:17
@spalladino
spalladino merged commit dd95801 into merge-train/spartan-v5 Aug 14, 2026
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@spalladino
spalladino deleted the spl/fix/checkpoint-block-shape-validation branch August 14, 2026 14:20
aminsammara added a commit that referenced this pull request Aug 17, 2026
Promotes `v5-next` onto `v5` for the **v5.2.0** release.

Frozen at `ee5d2d367e` — the `v5-next` tip at cut time. Both
`merge-train/spartan-v5` and `merge-train/fairies-v5` are drained to
that same commit, so nothing staged is left behind.

### Testnet validation

This branch was cut at `a4db216abf`, which is byte-identical to the
`v5.2.0-nightly.20260815` tag — same commit, same tree
(`0b22572eace2419ede6bbab173514d6965d4e0d0`). That nightly's CI3 run is
green, its artifacts are published to npm and Docker Hub, and it has
been **running healthily on testnet since 2026-08-15**:

| Component | Image / reported version |
|---|---|
| validators, prover node, prover broker, prover agents (`testnet` ns) |
`aztecprotocol/aztec:5.2.0-nightly.20260815` |
| `v5.testnet.rpc.aztec-labs.com` | `nodeVersion=5.2.0-nightly.20260815`
|
| `canonical.testnet.rpc.aztec-labs.com` |
`nodeVersion=5.2.0-nightly.20260815` |

Chain advancing normally, no prunes or reorgs, no WARN/ERROR across node
pods since rollout.

The branch has since been fast-forwarded to `ee5d2d367e` to pick up
#25242 (configurable RPC server HTTP timeouts and CORS allowed-headers).
That is the only delta from the soaked tree — 8 files, +131/−10, no
nightly covers it yet. Its config defaults were checked against Node's
built-ins (`keepAliveTimeout` 5000 ms, `headersTimeout` 60000 ms) and
match exactly, and the CORS default path resolves to the same `cors()`
call as before, so a node that sets none of the new env vars behaves
identically. It touches no circuits, protocol contracts, or generated
constants.

### Manifest

`.release-please-manifest.json` reads `5.2.0` on this branch, which is
the released version — correct as-is, no change needed in this PR.
`v5-next` moves to `5.3.0` separately in #25240; this branch is frozen
and cannot pick that up, so the two can merge in either order.

`v5` is a strict ancestor of `v5-next` this cycle, so there was no
manifest conflict to pre-resolve.

### Scope

139 commits (86 non-merge, 23 PR-level) spanning 2026-07-14 to
2026-08-17.

| Area | Theme |
|---|---|
| `prover-node` / `prover-client` | Epoch-proving robustness:
retry-to-converge with failure declared only at submission-window
expiry, ticker-driven expiry, per-checkpoint post-mortem upload,
checkpoint-only re-proving, prune-induced fault handling (#24678,
#24982, #24983, #24990, #25027) |
| `pxe` | Sync performance: hash-pinned node read cache (#24969),
anchor-bounded tag log caching (#25074), note/event validation from
cached tx data (#25076), constrained tag sync (#24275), sender tagging
finalization from log blocks (#25045) |
| `p2p` / `validator-client` | Gossip tx validation no longer stalls
behind tx-pool finalization (#25148); startup fails when p2p fails to
start (#25177); slashing/proposing/health/`sendTx` gated on p2p
connectivity (#25185); duplicate time-sensitive proposal validation
removed (#25207); `ValidatedProposal` branding (#25222) |
| `ethereum` / `aztec-node` | L1 watchers poll `getLogs` instead of
`eth_newFilter` (#25176); block stream sync no longer resolves against
an earlier pass (#25206) |
| `stdlib` / `foundation` | Deserialization bounds hardening (#25026,
#25028, #25029, #25109); checkpoint block-shape and block-count
validation (#25229); JSON-RPC cookies (#25231) |
| `archiver` | Removed-block cleanup and ownership-checked tx-effect
deletes (#24765); L2→L1 witness from a single store snapshot (#24754) |
| `aztec` | Declarative deployment framework at `@aztec/aztec/deploy`
(#24685) |
| `slasher` | Own-validator slash-target warnings and metrics (#25058) |
| telemetry | JSON-RPC metrics (#25159) |
| JSON-RPC server | Configurable HTTP keep-alive / headers timeouts and
CORS allowed-headers, defaults preserving current behaviour (#25242) |
| toolchain | Noir bumped to `v1.0.0-beta.25` (#24907) |

**One breaking change**, inherited from the Noir bump: note types
declared directly inside a `contract` module must now be `pub`.
Everything else is additive or internal.

### Protocol constants

Built from source and compared against `v5` — a cache-free rebuild of
every protocol circuit with each ref's own nargo and bb, then
regeneration of `vk_tree.ts` and `protocol_contract_data.ts`:

- `vkTreeRoot` =
`0x2b3b6ea4412b9c8f6457a37f91a2870306f8641e07e16a49b68bda6f8bc02892` —
unchanged from v5.1.0
- `protocolContractsHash` =
`0x2c075866eafc88a1f6f9addc7e337c6e64e45d1cb7fd7c0d612ebcec72aab2ca` —
unchanged from v5.1.0

The Noir beta.24 → beta.25 bump does not reach the circuits: the release
build consumes the committed `pinned-build.tar.gz`, which is
bit-identical between v5.1.0 and this commit (blob `3bedcb1fd1…`), so
the protocol-circuit bytecode is frozen rather than recompiled. The 47
verification keys were recomputed locally from that pinned bytecode with
the cache disabled, and all 47 `check_pinned_vk` checks passed.
`protocolContractsHash` is likewise backed by the new
`pinned-protocol-contracts.tar.gz`, whose three artifacts were
byte-compared against the build. Both values were also confirmed inside
the published `@aztec/protocol-contracts` and
`@aztec/noir-protocol-circuits-types` packages for
`5.2.0-nightly.20260815`.

That makes v5.2.0 a drop-in upgrade against the current rollup rather
than a coordinated one.

✅ **Gate re-run against `ee5d2d367e` (the current head) and passed** —
both values reproduced exactly from a build at this commit, with
`vkTreeRoot` numerically evaluated rather than inferred.
`29556326ce..ee5d2d3` touches no `noir-projects/**`,
`l1-contracts/src/**`, `ConstantsGen.sol`, `constants.gen.ts` or
`constants.nr`. Scope of the check: it verifies that the pinned circuit
bytecode plus locally recomputed VKs agree with the pin — not that a
from-source recompile reproduces v5.1.0's bytecode.

<details>
<summary>Commits added after the original constants check at
2955632</summary>

`#25207` `#25222` `#25206` `#25185` `#25176` `#25163` `#25229` `#25159`
`#25162` `#25231` `#25224` `#25228` `#25230` `#25242` plus their merge
commits.
</details>

### Known gap

Migration notes carry entries under `## TBD` that arrived with the docs
baseline backport (#25017) and describe `next`-line changes not present
on the v5 line — protocol contracts removed from
`@aztec/noir-contracts.js`, and the `at(wallet)` → `withWallet(wallet)`
deprecation. Neither exists on this branch. There is also no `## 5.1.0`
heading, and the entries that ship in v5.2.0 sit under `## TBD` rather
than a version heading.

This ships in the release docs, so it is worth correcting on `v5-next`
and backporting to `v5` before the tag, rather than after.
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