chore(amber): remove unused OrderingEnforcer

[aglinxinyuan]

What changes were proposed in this PR?

Deletes OrderingEnforcer, a generic helper in the amber engine with no production caller. Pure deletion, no behaviour change: −203 lines.

Removed	Lines	Why it is dead
architecture/messaginglayer/OrderingEnforcer.scala	53	last caller removed by #2208
architecture/messaginglayer/OrderingEnforcerSpec.scala	150	covers only the above

OrderingEnforcer was the extracted, generic form of the FIFO / exactly-once reorder buffer. #2208 ("Refactoring of amber engine", 2023-11-15) inlined that logic into AmberFIFOChannel, which still carries the identical header comment /* The abstracted FIFO/exactly-once logic */ and re-declares the same members:

OrderingEnforcer[T]  (deleted)        AmberFIFOChannel  (live, unchanged)
  ofoMap: LongMap[T]                    ofoMap: HashMap[Long, WorkflowFIFOMessage]
  current: Long                         current: Long
  isDuplicated / isAhead                isDuplicated / isAhead
  stash / enforceFIFO                   stash / enforceFIFO

The generic copy has been stranded for two and a half years.

Reviewer note: there is a separate, live OrderEnforcer trait (no -ing) in architecture/logreplay/, used by InputGateway/NetworkInputGateway. It is unrelated and untouched — only the messaginglayer OrderingEnforcer is removed here.

It acquired unit tests during the 2026 coverage work (#4721), which is why it currently looks live despite having been unreachable since 2023.

Scope change after review: this PR originally also removed Utils.retry. Per @Yicong-Huang's review it has been restored and is untouched here — Utils.scala and UtilsSpec.scala are byte-identical to main.

Any related issues, documentation, discussions?

Closes #7027

How was this PR tested?

Existing tests only — this PR adds none, since it removes code and the spec that covered it.

Locally, from the repo root with Java 17:

• sbt "scalafixAll --check" — clean.
• sbt scalafmtCheckAll — clean.
• sbt "WorkflowExecutionService/testOnly *UtilsSpec" — 74 tests, all pass (Utils.retry and its three tests are back and green).

Verification that nothing references the removed class, re-runnable by a reviewer:

git grep -nw OrderingEnforcer      # only the two deleted files

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Claude Opus 5)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• No candidates found from git blame history.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.26%. Comparing base (a61702f) to head (88ac489).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7028      +/-   ##
============================================
+ Coverage     79.20%   79.26%   +0.05%     
+ Complexity     3786     3775      -11     
============================================
  Files          1160     1159       -1     
  Lines         46118    46110       -8     
  Branches       5114     5113       -1     
============================================
+ Hits          36529    36549      +20     
+ Misses         7969     7942      -27     
+ Partials       1620     1619       -1     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)		Carriedforward from 3ff77d3
agent-service	76.76% <ø> (ø)		Carriedforward from 3ff77d3
amber	72.58% <ø> (+0.15%)	⬆️
computing-unit-managing-service	20.49% <ø> (ø)		Carriedforward from 3ff77d3
config-service	66.66% <ø> (ø)		Carriedforward from 3ff77d3
file-service	67.21% <ø> (ø)		Carriedforward from 3ff77d3
frontend	83.08% <ø> (ø)		Carriedforward from 3ff77d3
notebook-migration-service	78.94% <ø> (ø)		Carriedforward from 3ff77d3
pyamber	96.34% <ø> (ø)		Carriedforward from 3ff77d3
workflow-compiling-service	26.31% <ø> (ø)		Carriedforward from 3ff77d3

*This pull request uses carry forward flags. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

⚠️ Benchmark changes need a look

🟢 0 better · 🔴 15 worse · ⚪ 0 noise (<±5%) · 0 without baseline

CI benchmark results are noisy; treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	328	0.2	28,641/41,432/41,432 us	🔴 +163.3% / 🔴 +162.7%
🔴	bs=100 sw=10 sl=64	773	0.472	130,308/162,294/162,294 us	🔴 +42.8% / 🔴 +51.2%
🔴	bs=1000 sw=10 sl=64	891	0.544	1,111,614/1,218,279/1,218,279 us	🔴 +12.5% / 🔴 +18.6%

Baseline details

Latest main a61702f from 2026-07-29T14:37:20.598Z

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	328 tuples/sec	750.01 tuples/sec	786.12 tuples/sec	-56.3%	-58.3%
bs=10 sw=10 sl=64	MB/s	0.2 MB/s	0.458 MB/s	0.48 MB/s	-56.3%	-58.3%
bs=10 sw=10 sl=64	p50	28,641 us	12,994 us	12,305 us	+120.4%	+132.8%
bs=10 sw=10 sl=64	p95	41,432 us	15,738 us	15,774 us	+163.3%	+162.7%
bs=10 sw=10 sl=64	p99	41,432 us	18,799 us	18,978 us	+120.4%	+118.3%
bs=100 sw=10 sl=64	throughput	773 tuples/sec	938.38 tuples/sec	999.71 tuples/sec	-17.6%	-22.7%
bs=100 sw=10 sl=64	MB/s	0.472 MB/s	0.573 MB/s	0.61 MB/s	-17.6%	-22.6%
bs=100 sw=10 sl=64	p50	130,308 us	106,490 us	100,616 us	+22.4%	+29.5%
bs=100 sw=10 sl=64	p95	162,294 us	113,622 us	107,356 us	+42.8%	+51.2%
bs=100 sw=10 sl=64	p99	162,294 us	123,806 us	113,255 us	+31.1%	+43.3%
bs=1000 sw=10 sl=64	throughput	891 tuples/sec	966.12 tuples/sec	1,031 tuples/sec	-7.8%	-13.6%
bs=1000 sw=10 sl=64	MB/s	0.544 MB/s	0.59 MB/s	0.63 MB/s	-7.7%	-13.6%
bs=1000 sw=10 sl=64	p50	1,111,614 us	1,035,855 us	980,328 us	+7.3%	+13.4%
bs=1000 sw=10 sl=64	p95	1,218,279 us	1,083,196 us	1,027,528 us	+12.5%	+18.6%
bs=1000 sw=10 sl=64	p99	1,218,279 us	1,097,913 us	1,054,298 us	+11.0%	+15.6%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,610.05,200,128000,328,0.200,28641.07,41431.81,41431.81
1,100,10,64,20,2588.81,2000,1280000,773,0.472,130308.42,162294.41,162294.41
2,1000,10,64,20,22436.29,20000,12800000,891,0.544,1111614.35,1218279.48,1218279.48