feat: split gotestsum logs into per-test files

[ajsutton]

Summary

Adds two scripts under ops/scripts/:

• split-test-logs.sh — takes a gotestsum JSON log file and splits it into one .log file per test, organized as per-test/<package>/<TestName>.log next to the source JSON file.
• gotestsum-split.sh — drop-in gotestsum wrapper that runs gotestsum, then calls split-test-logs.sh. Preserves gotestsum's exit code so splits happen even on test failure (when they're most useful). If --jsonfile isn't provided, adds one automatically (tmp/testlogs/log.json) so per-test logs are always generated.

All gotestsum invocations in justfiles and CI config now use the wrapper. The one exception is the xargs-based parallel sharding in kona action tests, which calls gotestsum directly (xargs invokes it multiple times appending to one jsonfile) then calls split-test-logs.sh once at the end.

Per-test logs land under tmp/testlogs/per-test/ which is already captured by existing CircleCI store_artifacts steps.

Also migrates rust/op-reth/crates/tests from plain go test to gotestsum via the wrapper for consistency.

Files touched

File	Change
ops/scripts/split-test-logs.sh	New — splits a JSON log file into per-test files
ops/scripts/gotestsum-split.sh	New — gotestsum wrapper that auto-splits
justfile	Use wrapper in _go-tests-ci-internal and go-tests-fraud-proofs-ci
op-e2e/justfile	Use wrapper in _go_test variable
rust/kona/tests/justfile	Use wrapper + direct split for xargs case
rust/op-reth/tests/justfile	Use wrapper in test-e2e-sysgo
rust/op-reth/crates/tests/justfile	Migrate to gotestsum via wrapper
.circleci/continue/main.yml	Use wrapper for cannon tests

Test plan

• Verify split-test-logs.sh correctly splits a gotestsum JSON file into per-test logs locally
• Verify gotestsum-split.sh auto-adds --jsonfile when not provided
• Verify CI jobs still pass (test results and artifacts captured)
• Verify per-test logs appear in CircleCI artifacts under testlogs/per-test/
• Verify the split runs on test failure (exit code preserved)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.5%. Comparing base (ba64213) to head (0c1073e).
⚠️ Report is 16 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #19575     +/-   ##
==========================================
- Coverage     75.5%    75.5%   -0.1%     
==========================================
  Files          675      675             
  Lines        71562    71562             
==========================================
- Hits         54071    54059     -12     
- Misses       17347    17359     +12     
  Partials       144      144             

Flag	Coverage Δ
cannon-go-tests-64	66.4% <ø> (ø)
contracts-bedrock-tests	80.2% <ø> (ø)
unit	75.5% <ø> (-0.1%)	⬇️

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see 6 files with indirect coverage changes

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