Architecture — Remove the Legacy Agent Classifier Backfill

Status

Design for a review-driven change on an open pull request. This document is the single source of truth; the supporting docs (agent-classifier-backfill-removal-plan.md and agent-classifier-backfill-removal-testing.md) reuse the names, method signatures, and file paths defined here verbatim.

Note: an unrelated architecture.md / testing.md already exist in this directory for the Agent Worker design. This change owns the agent-classifier-backfill-removal-* file set and does not touch those.

Problem statement

The PR branch reintroduced a private backfill routine, AgentService.backfillLegacyAgentExecutionClassifiers(), in commit add-backfill-method, together with an end-to-end test that reflectively invokes it. Review feedback is explicit and takes precedence over the test:

@v1r3n: "do not add back backfillLegacyAgentExecutionClassifiers method. This method should not be added back."
@v1r3n: the test AgentSpanDeploymentContractEndToEndTest.legacyAgentClassifierBackfillUsesConcreteExecutionTimeBounds() currently fails with NoSuchMethodException for that method and must be fixed.

These two statements are only mutually consistent one way: the method stays removed, and the test that depends on it is removed as well. The test cannot be "fixed" by restoring the method, because restoring the method is precisely what the reviewer forbids. The correct resolution is therefore a removal, not an addition.

Scope and non-goals

This is a minimal, review-scoped change.

In scope

Remove the backfillLegacyAgentExecutionClassifiers() method and every private helper and constant that exists only to serve it.
Remove the end-to-end test that reflectively invokes the removed method.
Remove any import or injected field that becomes unused solely as a result of the removals above.

Out of scope

Any change to the compile/deploy classifier stamping that happens on the normal deploy() path.
The unrelated task-name "backfill" helpers (WorkflowTaskUtils.ensureAllTaskNames, referenced by MultiAgentCompiler); these are a different concept and must not be touched.
Adding a replacement backfill entry point of any kind.

Overview & tech stack

Language / build: Java 21, Gradle.
Affected runtime module: agentspan — the embedded agent runtime.
Affected test module: test-harness — cross-module integration tests.
Relevant collaborators of AgentService: MetadataDAO, ExecutionDAO, IndexDAO, and the workflow search service. Which of these remain injected is determined in agent-classifier-backfill-removal-plan.md by checking for other usages; none is removed unless it becomes unused only because of this change.

Complete file layout (files touched)

Only two source files are edited. No files are created; no new production code is written.

File	Responsibility	Change
`agentspan/src/main/java/org/conductoross/conductor/ai/agentspan/runtime/service/AgentService.java`	Embedded agent deploy/start/search service	Delete the backfill method chain and its now-dead constants/helpers/imports (see below).
`test-harness/src/test/java/com/netflix/conductor/test/integration/agent/AgentSpanDeploymentContractEndToEndTest.java`	Deployment-contract end-to-end tests	Delete the single test that reflectively invokes the removed method.

Shared contract — the exact removal set

Every supporting document refers to the identifiers in this table by these exact names. An identifier is removed only if its sole remaining caller is another member of this set (transitive dead-code elimination rooted at the backfill method).

In `AgentService.java`

Identifier	Kind	Current signature / value	Removed because
`backfillLegacyAgentExecutionClassifiers`	method	`private void backfillLegacyAgentExecutionClassifiers()`	Directly forbidden by review. Root of the dead-code chain.
`backfillVersionOf`	method	`private static int backfillVersionOf(Map<String, Object> metadata)`	Only caller is the backfill method.
`reindexAgentExecutions`	method	`private void reindexAgentExecutions(String agentName)`	Only caller is the backfill method (confirmed no other references in the file).
`AGENT_CLASSIFIER_BACKFILL_VERSION`	constant	`private static final String AGENT_CLASSIFIER_BACKFILL_VERSION = "agent_classifier_backfill_version"`	Only read by the removed methods.
`AGENT_CLASSIFIER_BACKFILL_VERSION_VALUE`	constant	`private static final int AGENT_CLASSIFIER_BACKFILL_VERSION_VALUE = 2`	Only read by the removed methods.

Imports and injected fields (indexDAO, executionDAO, the workflow search service, WorkflowSummary, SearchResult, WorkflowClassifiers, etc.) are removed case by case and only when a repository-wide check shows the removed methods were their last user. The concrete determination lives in agent-classifier-backfill-removal-plan.md.

In `AgentSpanDeploymentContractEndToEndTest.java`

Identifier	Kind	Removed because
`legacyAgentClassifierBackfillUsesConcreteExecutionTimeBounds`	`@Test` method	Its entire body exercises the forbidden method via reflection (`AgentService.class.getDeclaredMethod("backfillLegacyAgentExecutionClassifiers")`). With the method gone the test can only fail; it is deleted rather than restored.

Any import (e.g. java.lang.reflect.Method) left unused only by deleting this test method is also removed.

Consistency invariants

No new entry point. After the change there is no method — public, package-private, or private — named or aliased backfill*Classifiers on AgentService.
Symmetric removal. The production method and the test that references it are removed in the same change; neither is left orphaned.
Metadata key untouched at runtime. The string literal "agent_classifier_backfill_version" is only removed as an unused constant; the normal deploy path is not modified to write it (it did not, outside the backfill routine).
Compiles clean. No unused private members and no unused imports remain, so the module still builds under the project's strict formatting/lint settings.

Verification (design-level, not run here)

./gradlew :agentspan:compileJava — module compiles with the members removed.
./gradlew :test-harness:test --tests '*AgentSpanDeploymentContractEndToEndTest*' — the remaining tests pass; the deleted test no longer references a missing method.
./gradlew spotlessApply — formatting normalized after edits.