refactor(amber): rename Controller to Coordinator

[Yicong-Huang]

What changes were proposed in this PR?

Renames the Amber master actor from Controller to Coordinator across the whole engine — classes, variables, comments, protobuf, and tests:

Area	Change
Scala package	architecture.controller → architecture.coordinator (dirs moved with git mv)
Scala classes	Controller → Coordinator, ControllerProcessor → CoordinatorProcessor, ControllerConfig → CoordinatorConfig, ControllerAsyncRPCHandlerInitializer, ControllerTimerService, ControllerSpec → Coordinator*
gRPC proto	controllerservice.proto → coordinatorservice.proto; service ControllerService → CoordinatorService; rpc ControllerInitiateQueryStatistics → CoordinatorInitiateQueryStatistics; scalapb extends option and proto comments
Python runtime	controller_interface / _controller_service_stub / controller_stub → coordinator_*; generated betterproto bindings are gitignored and regenerate from the renamed proto (bin/python-proto-gen.sh verified)
Actor identity	CONTROLLER ActorVirtualIdentity constant → COORDINATOR (Scala + Python)
Location preference	PreferController → PreferCoordinator (workflow-core)
Variables / comments	all camelCase & snake_case variants (controllerConfig, controllerTimerService, controllerAddress, …) and prose in scaladoc/docstrings

The rename is purely mechanical (case-preserving substring replacement, verified exhaustively): grep -ri controller over amber/ and common/ returns zero matches afterwards. Untouched on purpose: Angular's HttpTestingController, the Web AbortController in agent-service, and Envoy's gatewayclass-controller in the k8s templates.

Follows #6123 (merged), which freed the Coordinator name by renaming the region-scheduling coordinators to managers.

Any related issues, documentation, discussions?

Closes #6122.

How was this PR tested?

Refactor with no behavior change — existing tests stay green with no assertion edits:

sbt "WorkflowCore/testOnly org.apache.texera.amber.core.workflow.WorkflowCoreTypesSpec org.apache.texera.amber.core.workflow.PhysicalOpSpec org.apache.texera.amber.util.VirtualIdentityUtilsSpec"
sbt "WorkflowOperator/testOnly org.apache.texera.amber.operator.SpecialPhysicalOpFactorySpec"
sbt "WorkflowExecutionService/testOnly org.apache.texera.amber.engine.architecture.coordinator.CoordinatorSpec org.apache.texera.amber.engine.architecture.coordinator.ClientEventSpec org.apache.texera.amber.engine.architecture.coordinator.WorkflowSchedulerSpec org.apache.texera.amber.engine.architecture.scheduling.WorkflowExecutionManagerSpec org.apache.texera.amber.engine.architecture.scheduling.RegionExecutionManagerSpec"
cd amber && python -m pytest src/test/python/core/architecture/rpc/test_async_rpc_client.py src/test/python/core/util/test_virtual_identity.py src/test/python/core/runnables/test_console_message.py src/test/python/core/runnables/test_data_processor.py src/test/python/core/runnables/test_main_loop.py src/test/python/pytexera/storage/test_large_binary_manager.py

Full Test/compile of WorkflowCore, WorkflowOperator, and WorkflowExecutionService passes; Python bindings regenerated via bin/python-proto-gen.sh and 68 pytest cases pass.

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

Generated-by: Claude Code (Claude Fable 5)

[github-actions]

Automated Reviewer Suggestions

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

• Contributors with relevant context: @aglinxinyuan, @Ma77Ball, @kunwp1
  You can notify them by mentioning @aglinxinyuan, @Ma77Ball, @kunwp1 in a comment.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.21277% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.15%. Comparing base (3084881) to head (63ef84c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../engine/architecture/coordinator/Coordinator.scala	66.66%	6 Missing and 1 partial ⚠️
...exera/amber/engine/common/client/ClientActor.scala	66.66%	1 Missing and 2 partials ⚠️
.../texera/web/service/WorkflowExecutionService.scala	25.00%	3 Missing ⚠️
...rg/apache/texera/web/service/WorkflowService.scala	0.00%	3 Missing ⚠️
...ber/engine/architecture/worker/DataProcessor.scala	66.66%	2 Missing ⚠️
amber/src/main/python/core/runnables/main_loop.py	80.00%	1 Missing ⚠️
...hitecture/common/PekkoActorRefMappingService.scala	0.00%	0 Missing and 1 partial ⚠️
...inator/CoordinatorAsyncRPCHandlerInitializer.scala	50.00%	0 Missing and 1 partial ⚠️
...promisehandlers/RetrieveWorkflowStateHandler.scala	0.00%	1 Missing ⚠️
...dinator/promisehandlers/RetryWorkflowHandler.scala	0.00%	1 Missing ⚠️
... and 5 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6124      +/-   ##
============================================
+ Coverage     59.14%   59.15%   +0.01%     
- Complexity     3201     3207       +6     
============================================
  Files          1132     1132              
  Lines         43681    43681              
  Branches       4734     4734              
============================================
+ Hits          25833    25838       +5     
+ Misses        16416    16407       -9     
- Partials       1432     1436       +4     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)
agent-service	44.59% <ø> (ø)		Carriedforward from 3084881
amber	63.16% <67.85%> (+0.04%)	⬆️
computing-unit-managing-service	0.00% <ø> (ø)
config-service	52.30% <ø> (ø)
file-service	62.81% <ø> (ø)
frontend	51.37% <ø> (ø)		Carriedforward from 3084881
notebook-migration-service	78.57% <ø> (ø)
pyamber	91.14% <90.00%> (-0.05%)	⬇️
workflow-compiling-service	55.14% <ø> (ø)

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

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[github-actions]

⚠️ Benchmark changes need a look

🟢 2 better · 🔴 7 worse · ⚪ 6 noise (<±5%) · 0 without baseline

Compared against main 3a12e62 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	368	0.224	26,885/32,284/32,284 us	🔴 +13.0% / 🔴 +113.2%
🔴	bs=100 sw=10 sl=64	769	0.469	130,745/153,998/153,998 us	🔴 +10.8% / 🔴 +42.7%
⚪	bs=1000 sw=10 sl=64	896	0.547	1,114,774/1,152,459/1,152,459 us	⚪ within ±5% / 🔴 +12.6%

Baseline details

Latest main 3a12e62 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	368 tuples/sec	401 tuples/sec	776.36 tuples/sec	-8.2%	-52.6%
bs=10 sw=10 sl=64	MB/s	0.224 MB/s	0.245 MB/s	0.474 MB/s	-8.6%	-52.7%
bs=10 sw=10 sl=64	p50	26,885 us	23,782 us	12,636 us	+13.0%	+112.8%
bs=10 sw=10 sl=64	p95	32,284 us	35,710 us	15,143 us	-9.6%	+113.2%
bs=10 sw=10 sl=64	p99	32,284 us	35,710 us	18,954 us	-9.6%	+70.3%
bs=100 sw=10 sl=64	throughput	769 tuples/sec	809 tuples/sec	985.33 tuples/sec	-4.9%	-22.0%
bs=100 sw=10 sl=64	MB/s	0.469 MB/s	0.494 MB/s	0.601 MB/s	-5.1%	-22.0%
bs=100 sw=10 sl=64	p50	130,745 us	123,461 us	101,671 us	+5.9%	+28.6%
bs=100 sw=10 sl=64	p95	153,998 us	138,992 us	107,939 us	+10.8%	+42.7%
bs=100 sw=10 sl=64	p99	153,998 us	138,992 us	113,798 us	+10.8%	+35.3%
bs=1000 sw=10 sl=64	throughput	896 tuples/sec	911 tuples/sec	1,016 tuples/sec	-1.6%	-11.8%
bs=1000 sw=10 sl=64	MB/s	0.547 MB/s	0.556 MB/s	0.62 MB/s	-1.6%	-11.8%
bs=1000 sw=10 sl=64	p50	1,114,774 us	1,091,741 us	989,693 us	+2.1%	+12.6%
bs=1000 sw=10 sl=64	p95	1,152,459 us	1,144,658 us	1,028,327 us	+0.7%	+12.1%
bs=1000 sw=10 sl=64	p99	1,152,459 us	1,144,658 us	1,059,969 us	+0.7%	+8.7%

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
0,10,10,64,20,544.12,200,128000,368,0.224,26885.04,32284.48,32284.48
1,100,10,64,20,2601.08,2000,1280000,769,0.469,130744.76,153998.48,153998.48
2,1000,10,64,20,22330.96,20000,12800000,896,0.547,1114773.91,1152459.44,1152459.44