add unit test coverage for agent-service workflow-crud-tools (add / modify / delete operator tools)

[mengw15]

Task Summary

agent-service/src/agent/tools/workflow-crud-tools.ts (codecov ~22%) exports createAddOperatorTool, createModifyOperatorTool, createDeleteOperatorTool — factories returning AI-SDK tools whose execute(args) mutate an in-memory WorkflowState. Unit-testable with bun test: construct a real WorkflowState, build the tool, call tool.execute(args), assert the state change + returned result. Only mock is context.metadataStore.validateOperatorProperties for the validation branches — no network. See tools/tools-utility.spec.ts for the pattern.

Behavior to cover

createDeleteOperatorTool

• operator exists -> removes it (and connected links); returns "Deleted operator: {operatorId}"
• operator absent -> createErrorResult("Operator {operatorId} not found")

createAddOperatorTool

• unknown operatorType (no schema entry) -> error
• operatorId not matching /^op\d+$/ -> error
• operatorId already present -> error ("... already exists. Use modifyOperator ...")
• properties failing validation -> error carrying the validation messages
• inputOperatorIds referencing a missing source operator -> error ("Source operator ... not found")
• target port index NaN / negative / >= inputPorts.length -> error
• valid args -> adds operator + creates links; returns success

createModifyOperatorTool

• operator not found -> createErrorResult("Operator {operatorId} not found ...")
• merged properties failing validation -> error via formatValidationErrors(validation)
• valid args -> updates the operator's properties; returns success

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other