The Katalon Blog

The Human-in-the-Loop Advantage

Written by Richie Yu | Sep 25, 2025 4:00:00 PM

If AI is the engine, human-in-the-loop is the steering.

The rise of agentic testing systems has sparked real enthusiasm and real concern. Enterprises want to move faster and scale quality efforts without ballooning headcount. But trust, explainability, and control can’t be optional.

The answer isn’t full autonomy.
It’s human-in-the-loop (HITL)  where AI accelerates, and humans stay in control.

Why HITL Is the Smart Default

AI testing agents are now capable of:

  • Parsing logs and flagging anomalies
  • Generating test cases from user stories or Swagger
  • Grouping and labeling defects
  • Summarizing test results for release meetings

That sounds great but would you trust any of those steps to happen automatically and silently?

In complex, regulated environments, judgment is the last mile.
And that’s where humans must remain actively involved.

HITL isn’t a workaround - it’s how you make AI reliable in the real world.

When HITL Is Missing: A Real Scenario

A consumer banking platform used an LLM-based test agent to generate end-to-end test scenarios from Gherkin feature files. It worked well until it didn’t.

One day, an agent incorrectly assumed a new optional field meant a required authentication flow was obsolete. It removed the test.

No one caught it.

The release went through. Customers couldn’t authenticate.
Production was rolled back. An incident report followed.

Root cause? No human reviewed the agent’s change.
There was no approval checkpoint, no audit trail, no escalation trigger.

The testing team wasn’t the problem.
The governance model was.

How HITL Works in Practice

Human-in-the-loop simply means AI makes suggestions, and humans validate or act on them.

Here are examples across the test lifecycle:

Lifecycle Stage AI Agent Suggests Human Reviews or Acts
Design Drafts test scenarios Approves, edits, flags gaps
Test Generation Produces test cases Validates logic, adds edge cases
Execution Flags flaky tests or odd logs Investigates or dismisses
Triage Clusters bugs, suggests cause Validates priority, escalates
Reporting Summarizes test coverage and risk Edits language, contextualizes insights

This gives you scale without surrendering control.

HITL Fits Enterprise Risk Postures

Why does HITL work so well for large organizations?

  • Explainability: Stakeholders can ask why something happened
  • Traceability: Every step can be audited
  • Control: Final decisions stay with accountable humans
  • Trust-building: Teams adopt AI faster when they remain involved
  • Adaptability: Humans can correct misfires in real time

Manual vs. HITL vs. Autonomous Testing

Criteria Manual Testing HITL Testing Fully Autonomous
Speed Slow Faster Fastest
Coverage Limited Expanding Expanding
Control Full Configurable Often unclear
Explainability Easy Moderate Often opaque
Risk Managed Guarded High if unbounded
Adoption Readiness Known Incremental Requires high trust

HITL strikes the balance, giving you leverage without losing visibility.

How to Implement HITL in Agentic Testing

You don’t need an elaborate orchestration platform. Here’s how to start simply:

1. Define Agent Scope

What can the agent suggest, and what must be approved?

  • ✅ Generate test cases?
  • ❌ Approve release gates?

Make boundaries explicit from Day 1.

2. Add Approval Layers

Use pull requests, ticket workflows, or in-app approvals for:

  • Generated test scripts
  • Defect categorizations
  • Coverage recommendations

If you can’t afford human review, the task probably isn’t safe for full autonomy.

3. Log Everything

Treat agent suggestions like system actions:

  • Timestamped input/output logs
  • Confidence scores (if available)
  • Who approved/overrode the suggestion

This turns AI output into an auditable asset, not a black box.

4. Use Feedback to Improve Agents

Treat humans not just as gatekeepers but as trainers:

  • Capture feedback signals
  • Use thumbs up/down, comment threads, or scoring prompts
  • Improve prompt strategies, fine-tunes, or rulesets

This turns HITL into a virtuous cycle of improvement.

HITL Is Not a Bottleneck - It’s a Flywheel

Some fear that adding human checkpoints will slow things down.

In reality, well-designed HITL systems accelerate trust and reduce downstream waste:

  • Fewer surprise regressions
  • Fewer incidents needing root cause analysis
  • More adoption across teams
  • Higher quality outputs - faster

When humans stay involved, they trust the system.
And trust unlocks scale.

Bonus: HITL as a Guardrail for LLMs

LLM-powered agents introduce unique risks:

  • Probabilistic outputs
  • Hallucination of test steps or flows
  • Lack of business context

HITL becomes the safety harness - a fast way to use LLMs responsibly:

  • Use AI to generate
  • Use humans to curate
  • Use logs to govern

This is how leading teams adopt LLM agents without waking up in incident review meetings.

Final Thought: The Future is Collaborative

Testing isn’t going fully autonomous  and it shouldn’t.
Enterprise-grade quality requires nuance, context, and accountability.

But testing can be more scalable, intelligent, and adaptive  when humans and agents collaborate by design.

Human-in-the-loop isn’t a constraint. It’s an enabler.
It’s how we scale judgment, not just automation.

Coming Up Next:

Blog 4: Governance for AI in Testing - You Can’t Just Plug It In
We'll explore how to operationalize controls, auditability, and model risk tiers so you can confidently scale agentic testing in regulated environments.