[Java] Add replay-proxy E2E coverage for inline lambda-defined tools

[Copilot]

This change covers Phase 4.5 of the Java tool-as-lambda work by adding real-session E2E validation for inline lambda-defined tools against the replay proxy. It verifies both assistant-visible behavior and in-session tool side effects while following the existing snapshot-reuse strategy.

• E2E coverage: inline lambda tool definitions

  • Extended ErgonomicToolDefinitionIT with lambdaToolDefinition().
  • Defines tools inline via ToolDefinition.from(...) + Param.of(...) (no annotation-processor path).
  • Exercises the same end-to-end prompt/tool-invocation flow used by existing tool-definition integration tests.

• Behavior asserted in-session

  • Confirms assistant response includes expected phase/search content.
  • Confirms lambda tool side effect (currentPhase) mutates to "analyzing" during the session.

• Snapshot strategy + plan bookkeeping

  • Reuses existing tools/ergonomic_tool_definition snapshot (no new test/snapshots/tools/* YAML needed).
  • Marks Phase 4.5 complete in the implementation plan checklist.

ToolDefinition setCurrentPhase = ToolDefinition.from(
    "set_current_phase",
    "Sets the current phase of the agent",
    Param.of(String.class, "phase", "The phase to transition to"),
    phase -> {
        tools.currentPhase = phase;
        return "Phase set to " + phase;
    });

[github-actions]

Cross-SDK Consistency Review ✅

This PR adds E2E replay-proxy coverage for Java's ToolDefinition.from(...) + Param.of(...) lambda-based tool definition API (Phase 4.5 of the Java tool-as-lambda work). The changes are test-only (plus a planning doc update), so I focused on whether the feature under test has equivalent coverage in other SDKs.

Summary

No cross-SDK consistency issues found. All six SDK implementations already provide their own language-idiomatic ergonomic tool definition patterns:

SDK	Ergonomic inline tool pattern
Java (this PR)	ToolDefinition.from(name, desc, Param.of(...), lambda)
Node.js	defineTool(name, { description, parameters: zodSchema, handler })
Python	define_tool(description=..., handler=fn) / @define_tool decorator
Go	DefineTool[T](name, desc, func(T, ToolInvocation) (any, error))
.NET	CopilotTool.DefineTool(name, ...) with delegate handler
Rust	ToolHandler trait + schema_for::<T>()

All SDKs have equivalent mechanisms for defining tools inline without manually constructing raw JSON schema maps. The Param.of(...) pattern is Java's idiomatic approach and is appropriately gated with @CopilotExperimental.

Minor observation

The class-level Javadoc for ErgonomicToolDefinitionIT still describes only the @CopilotTool + fromObject() path:

/**
 * Failsafe integration test for the ergonomic {`@code` `@CopilotTool`} +
 * {`@code` ToolDefinition.fromObject()} API.

Now that the class also covers the ToolDefinition.from(...) / lambda path, it may be worth updating the class-level doc to mention both approaches. This is not a blocking issue.

---

Reviewed for cross-SDK API consistency across Node.js, Python, Go, .NET, Java, and Rust implementations.

Generated by SDK Consistency Review Agent for issue #1881 · sonnet46 1.3M · ◷

[Copilot]

Pull request overview

Adds Java failsafe E2E coverage to validate the inline/lambda ToolDefinition.from(...) + Param.of(...) tool-definition path against the replay proxy, ensuring it produces the same end-to-end behavior (and snapshot compatibility) as the existing annotation-based ergonomic tool API.

Changes:

• Extends ErgonomicToolDefinitionIT with a new lambdaToolDefinition() integration test that defines tools inline using ToolDefinition.from(...) and Param.of(...).
• Asserts both assistant-visible output (phase + search results) and an in-process side effect (currentPhase mutation) during the session.
• Marks Phase 4.5 (“E2E integration test”) complete in the implementation plan checklist.

Show a summary per file

File	Description
java/src/test/java/com/github/copilot/e2e/ErgonomicToolDefinitionIT.java	Adds a new replay-proxy-backed E2E test covering inline lambda-defined tools via ToolDefinition.from(...) + Param.of(...).
1810-java-tool-ergonomics-tool-as-lambda-remove-before-merge/1810-ignorance-reduction-for-implementation-plan.md	Updates the Phase 4.5 checklist item to completed.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Low