Context

SaaS did not only define how software is delivered. It defined how services are interacted with.

That interaction model is changing as AI agents become the next primary users of software services.

When the user is no longer a human clicking a UI, validation methods must also change.

Three Interface Generations

SaaS 1.0 — Software as a Service

Interface defaults to GUI.

Humans click, input, configure. Work is expressed as forms and workflows.

SaaS 2.0 — Service as Agent Service

Interface shifts toward language.

A sentence becomes an invocation. An agent acts across tools and systems.

This is not merely “chat inside SaaS.” It is a change in who the user is.

SaaS 3.0 — Service as Agent–Contract Service

Interface approaches semantic contract.

Execution, responsibility, and payment are expressed as a single governable unit.

The service boundary becomes:

  • executable,
  • accountable,
  • and economically settled by design.

This layer is not fully standardized yet, but the direction becomes visible once agents are treated as actors.

Why MVP Becomes Misaligned

MVP validates interaction surfaces.

But when the unit of execution is already language, UI-first validation introduces structural noise.

In language-native systems, the question is not whether a dashboard convinces a user.

The question is whether the structure is stable under execution:

  • can agents coordinate without context collision,
  • can authorization and delegation persist across runs,
  • can responsibility be reconstructed from traces.

MVS as the Correct Validation Unit

MVS validates structure, not surface.

It validates:

  • sentence formats that trigger action,
  • task grammars for multi-agent execution,
  • authorization and delegation embedded in language,
  • stability across language interfaces.

For agent-native services, shipping an interface demo can be misleading.

The relevant deliverable is a grammar.

Closing Observation

We are entering a post-SaaS transition not because software disappears, but because the user changes.

If the next user is an agent, services must be designed as structures that agents can execute.

MVS becomes the correct validation target, because structure is the new interface.