Restore Taiko FCU timestamp validation allowing equal timestamps by jmadibekov · Pull Request #10810 · NethermindEth/nethermind

jmadibekov · 2026-03-12T15:57:21Z

Changes

Add IsPayloadTimestampValid virtual method to ForkchoiceUpdatedHandler (base: > for strict increase)
Override in TaikoForkchoiceUpdatedHandler as a one-liner using >= (allowing equal timestamps)
Reduce timeout-minutes from 45 to 20 in ci-surge.yml and ci-taiko.yml, add step-level 15m timeout on the test step so timeouts surface as failures instead of cancellations
Add unit tests covering equal, greater, and lesser timestamp scenarios

PR #10325 renamed IsPayloadAttributesTimestampValid → ArePayloadAttributesTimestampAndSlotNumberValid, removed virtual, and deleted the Taiko override. In Taiko, multiple L2 blocks can be derived from a single L1 block sharing the same L1 anchor timestamp, so equal timestamps must be allowed.

Types of changes

What types of changes does your code introduce?

Bugfix (a non-breaking change that fixes an issue)

Testing

Requires testing

Yes

If yes, did you write tests?

Yes

Notes on testing

Added 3 test cases in TaikoEngineApiTests verifying equal timestamps are accepted, greater timestamps are accepted, and lesser timestamps are rejected.

Integration tests passed on this PR:

Documentation

Requires documentation update

No

Requires explanation in Release Notes

No

…amps Commit 195829e (Bal devnet 2) renamed IsPayloadAttributesTimestampValid, removed the virtual keyword, and deleted TaikoForkchoiceUpdatedHandler's override that allowed equal timestamps. This broke Taiko Pacaya where multiple L2 blocks derived from a single L1 block share the same timestamp.

LukaszRozmej

Maybe make the change smaller by having something like GetMinRequiredTimestamp overridable. Thus overriding a one-liner?

smartprogrammer93 · 2026-03-12T16:13:16Z

@copilot implement the following suggestion to this PR::

Maybe make the change smaller by having something like GetMinRequiredTimestamp overridable. Thus overriding a one-liner?

Copilot · 2026-03-12T16:13:24Z

@smartprogrammer93 I've opened a new pull request, #10811, to work on those changes. Once the pull request is ready, I'll request review from you.

Job-level timeout 45m → 20m, add step-level 15m timeout on the test step so timeouts show as failures instead of cancellations.

LukaszRozmej · 2026-03-13T08:07:15Z

src/Nethermind/Nethermind.Merge.Plugin/Handlers/ForkchoiceUpdatedHandler.cs

-        if (newHeadBlock.Timestamp >= payloadAttributes.Timestamp)
+        if (payloadAttributes.Timestamp < GetMinRequiredTimestamp(newHeadBlock))
        {
            string error = $"Payload timestamp {payloadAttributes.Timestamp} must be greater than block timestamp {newHeadBlock.Timestamp}.";


This message should be adjusted to use GetMinRequiredTimestamp too - save it in variable.

Also not sure which would be better here < or <= (which would require amending GetMinRequiredTimestamp accordingly), WDYT?

Regarding the first comment, done! Regarding the second, I'd rather leave it as-is (that is <) because I find that more readable.

Actually, I went ahead with the approach @dipkakwani suggested below because I found that even more elegant :)

But the error message for taiko is now wrong?

dipkakwani · 2026-03-13T09:35:20Z

src/Nethermind/Nethermind.Taiko/Rpc/TaikoForkchoiceUpdatedHandler.cs


+    // Taiko Pacaya allows equal timestamps because multiple L2 blocks can be derived
+    // from a single L1 block, all sharing the same L1 anchor timestamp.
+    protected override ulong GetMinRequiredTimestamp(Block newHeadBlock) => newHeadBlock.Timestamp;


This change will allow equal timestamps for all the forks, not just Pacaya right?
We need to have conditions to return based on the current fork, similar to taiko geth here: https://github.com/taikoxyz/taiko-geth/blob/1fda81a9372dd79056427487caef38cee2be75b5/consensus/taiko/consensus.go#L158-L168

Actually, we do already have similar per-fork rules during block validation: https://github.com/NethermindEth/nethermind/blob/master/src/Nethermind/Nethermind.Taiko/TaikoHeaderValidator.cs#L204-L226.

And when it comes to fcu, nmc is actually correctly mirroring here taiko-geth because taiko-geth also allows equal timestamps for all forks unconditionally: https://github.com/taikoxyz/taiko-geth/blob/taiko/miner/worker.go#L174-L187.

So I don't think there is a need for this.

dipkakwani · 2026-03-13T09:41:40Z

src/Nethermind/Nethermind.Merge.Plugin/Handlers/ForkchoiceUpdatedHandler.cs

        return null;
    }

+    protected virtual ulong GetMinRequiredTimestamp(Block newHeadBlock) => newHeadBlock.Timestamp + 1;


This function looks a bit random, the intention of adding 1 to the timestamp is not clear.
Do you think it wil be better to have the complete logic for checking timestamp as virtual, instead of only the minimum required timestamp? Something like IsPayloadTimestampValid in the if statement of line 296, and each module can override that function?

Just noticed the linked PR, not sure why it was removed. The existing IsPayloadTimestampValid https://github.com/NethermindEth/nethermind/pull/10325/changes#diff-74bac6db7a134940f36bb275f9bd355e45f5428bf5f30cd4bd2b7fccd2b1b186

Also noticed Lukaz comment, I think we can still make IsPayloadTimestampValid one-liner in the base class instead of using GetMinRequiredTimestamp.

I like that, done!

codecov · 2026-03-13T19:37:19Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (8964a2e) to head (8ce5731).
⚠️ Report is 29 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #10810       +/-   ##
===========================================
- Coverage   50.22%        0   -50.23%     
===========================================
  Files        3207        0     -3207     
  Lines      165267        0   -165267     
  Branches    23135        0    -23135     
===========================================
- Hits        83010        0    -83010     
+ Misses      76622        0    -76622     
+ Partials     5635        0     -5635

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jmadibekov requested review from LukaszRozmej, Marchhill, MarekM25, benaadams, dipkakwani, flcl42 and smartprogrammer93 as code owners March 12, 2026 15:57

github-actions bot added bug fix + reliability taiko related to the taiko alethia rollup labels Mar 12, 2026

jmadibekov self-assigned this Mar 12, 2026

jmadibekov changed the title ~~fix: Restore Taiko FCU timestamp validation allowing equal timestamps~~ Restore Taiko FCU timestamp validation allowing equal timestamps Mar 12, 2026

LukaszRozmej reviewed Mar 12, 2026

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Resolve comment

e8fdfe3

Copilot AI mentioned this pull request Mar 12, 2026

Restore Taiko FCU timestamp validation allowing equal timestamps #10811

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smartprogrammer93 approved these changes Mar 12, 2026

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Reduce CI timeout for Surge/Taiko integration tests

8bd8bb2

Job-level timeout 45m → 20m, add step-level 15m timeout on the test step so timeouts show as failures instead of cancellations.

jmadibekov requested review from a team and rubo as code owners March 12, 2026 17:44

github-actions bot added the devops label Mar 12, 2026

LukaszRozmej reviewed Mar 13, 2026

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dipkakwani reviewed Mar 13, 2026

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jmadibekov added 3 commits March 13, 2026 11:23

Use variable

3ff4ff8

Merge branch 'master' into jmadibekov/fix-taiko-fcu-timestamp-validation

be50a25

Replace GetMinRequiredTimestamp with IsPayloadTimestampValid one-liner

40de70b

LukaszRozmej approved these changes Mar 13, 2026

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dipkakwani approved these changes Mar 13, 2026

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Use generic error message for payload timestamp validation

6020b8d

dipkakwani approved these changes Mar 13, 2026

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Merge branch 'master' into jmadibekov/fix-taiko-fcu-timestamp-validation

8ce5731

jmadibekov merged commit a438f5e into master Mar 13, 2026
415 of 416 checks passed

jmadibekov deleted the jmadibekov/fix-taiko-fcu-timestamp-validation branch March 13, 2026 19:36

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codecov bot commented Mar 13, 2026

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