“When last we left our humble explorers, I was asking questions about whether AI-enabled browsers—AI browsers for short—should be described as Web User Agents as defined by the W3C.”

In that earlier post, the answer was mostly yes. AI-enabled browsers still retrieve web content, interpret it, and act on behalf of a user. From a purely functional perspective, they fit reasonably well within the current model.

But it’s never that easy. That answer leads to interesting follow-up questions for the web.

If AI browsers do qualify as web user agents, what, if anything, needs to change in the definition of Web User Agent? Even bigger: what might need to change in the Web Platform Design Principles and the Ethical Web Principles that come along with that definition, to make that answer a complete and comfortable yes?

As with all of my posts, these thoughts reflect my own perspective. This topic has also come up in client conversations recently, which suggests it’s starting to appear in more places than just standards discussions. But to be clear, I’m not speaking on behalf of anyone here.

This is alllll me.

To begin unpacking this, it’s useful to revisit a few of the documents that define the architectural and ethical heart of the web.

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The Priority of Constituencies as a Design Constraint

One of the foundational ideas behind the web platform is the Priority of Constituencies, which appears in the Web Platform Design Principles.

It establishes a simple ordering:

User needs come before the needs of web page authors, which come before the needs of user agent implementors, which come before the needs of specification writers, which come before theoretical purity.

This principle is more than philosophical guidance. In practice, it acts as a design constraint.

Browsers—the most common form of user agent—are expected to prioritize the interests of the person using them. Many of the web’s security and privacy mechanisms exist specifically because browsers are meant to act as a protective intermediary between users and the broader web ecosystem.

Thank you, web browsers.

If AI browsers become powerful automation systems, maintaining that role becomes more complicated.

At a minimum, the platform would need to ensure several things remain true:

• the browser continues to protect the user
• automation does not undermine user safety
• the user remains aware of actions taken on their behalf

Without those safeguards, the browser stops functioning as a user defender and becomes simply an automation tool. That would represent a significant architectural shift for the web.

Historically, the browser’s role has been fairly straightforward:

Traditional browser → shows the web to the user

But with AI-enabled features expanding, the role begins to change:

AI browser → acts on the web for the user

Both models can technically fall under the definition of a user agent. But the second introduces governance and accountability questions that the current user-agent model does not fully address.

AI browsers introduce a user proxy model

One useful way to think about AI browsers is that they introduce a user proxy model. Instead of simply exposing web content to the user, the browser becomes a representative acting on the user’s behalf.

This shift has implications for several parts of the ecosystem.

For users

The browser must remain aligned with the user’s interests.

This sounds obvious, but it becomes more complicated when decisions are delegated to automated systems. If the browser is performing actions independently, how confident can we be that those actions reflect the intent and priorities of the specific user?

For websites

Websites must decide whether to treat the browser’s actions as equivalent to the user’s actions.

If a browser automatically researches information across many pages, fills out forms, or interacts with services programmatically, does that still count as a human interaction? Or should those behaviors be treated more like automated agents or bots?

There’s some critical work going on in the IETF to standardize how to signal a website’s preferences regarding AI behavior (AI Preferences Working Group) and authentication (Web Bot Auth Working Group).

Those discussions are spicy.

For the web platform

The Priority of Constituencies places the needs of user agent implementors (e.g., browser vendors) after users and web authors, but before specification writers and theoretical purity.

In practical terms, this means the people building browsers carry a significant responsibility. They are the ones who ultimately translate design principles into working systems. Their engineering choices determine how users interact with the web and how safely those interactions occur. AI-enabled browsers introduce a new set of pressures on that role.

If browsers begin interpreting user intent and performing actions on behalf of users, implementors must grapple with questions that the traditional user-agent model largely avoided.

For example:

• How transparent should delegated actions be to the user? Remember that cognitive load is a thing that applies both to the website and the web platform.
• What boundaries should exist around autonomous browsing behavior?
• How should permissions apply when actions occur after the original user request?
• What safeguards prevent automation from drifting beyond what the user intended?

These are not purely philosophical concerns. They quickly turn into engineering questions about user interfaces, permission models, auditability, and failure modes.

Browser developers have historically acted as a stabilizing force for the web platform, implementing safeguards that protect users even when the broader ecosystem pushes in other directions. AI-enabled browsing may require a new generation of those safeguards.

In effect, browser implementors may need to decide how much autonomy is acceptable within a system that is still expected to represent and defend the interests of its users.

Hopefully, they’ll work with the standards architects to define that behavior in a way that supports interoperability across the web.

For the theoretical purists

Which brings us to the standards architects trying to define correct, interoperable behavior.

Standards architects need to determine how to describe the limits of delegated actions. But that discussion intersects with other areas of architecture and governance, including:

• permission models
• identity and authentication
• accountability mechanisms
• bot detection
• automation policies

None of these is entirely new. But the scale and autonomy implied by AI-enabled browsing could amplify them in ways that existing design assumptions did not anticipate.

What makes this particularly interesting is that many of these areas are not traditionally part of web architecture discussions.

The communities working on identity standards, for example, only partially overlap with the people working on web platform standards. The same is true for AI governance and AI technical standards. Each of these communities has its own priorities, terminology, and problem spaces.

That separation is understandable. There is simply too much work to do across the technology landscape for every standards effort to coordinate deeply with every other one. Work naturally happens in silos, focused on solving the immediate problems within a specific domain.

You can see this pattern today. Every standards organization I’m familiar with has groups focused on AI. Those groups are tackling urgent questions about safety, transparency, model behavior, and accountability.

At the same time, web standards groups continue to focus on browser behavior, APIs, security boundaries, and interoperability.

These conversations are related—but they do not always happen in the same room.

AI browsers sit right at the intersection of these worlds. They bring together web architecture, identity and delegation models, and emerging AI capabilities in a way that forces these conversations to overlap, whether the standards communities are ready for it or not.

For those concerned with architectural coherence—the theoretical purists in the Priority of Constituencies—this raises a big challenge: ensuring that the resulting systems still behave in ways that are predictable, interoperable, and aligned with the long-standing principles of the web, even when some of the critical work doesn’t think of itself as web-based at all.

A Small Shift with Large Implications

The underlying shift here is easy to describe but significant in its implications. Browsers are moving from systems that mediate interactions with the web to systems that may act within the web ecosystem on behalf of users.

That evolution does not automatically break the user-agent model. But it does place new pressure on the assumptions embedded in that model, particularly the assumption that the browser reliably represents the user’s interests.

To be clear, I think the existing design principles for the web are remarkably solid. The Priority of Constituencies, the Web Platform Design Principles, and the Ethical Web Principles have guided the development of the web for decades in ways that have generally served users well. I don’t see a need to significantly rewrite them.

What may be needed, however, is clearer guidance on how those principles apply in a world where user agents are beginning to blur the line between the user and everything acting on their behalf.

If browsers become more autonomous, maintaining alignment with the user’s interests may require stronger expectations around transparency, clearer boundaries around delegated actions, or new architectural patterns for representing user intent.

The web benefits from asking architectural questions early, before emerging behaviors become deeply embedded in the ecosystem. As “AI browsers” eventually become simply “browsers,” this seems like a good moment to start thinking about what that future should look like.

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Transcript

Introduction

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[00:00:00]

Welcome to the Digital Identity Digest, the audio companion to the blog at Spherical Cow Consulting.

I’m Heather Flanagan, and each week I break down interesting topics in digital identity—from credentials and standards to browser quirks and policy shifts.

If you work in this space but don’t have time to follow every spec or hype cycle, you’re in the right place.

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Revisiting the User Agent Question

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[00:00:26]

Let’s dive in.

In the last discussion, we explored whether AI-enabled browsers—what we might call AI browsers—should be considered web user agents.

At a high level, the answer was mostly yes.

After all, these browsers still:

• Retrieve web content
• Interpret information
• Act on behalf of the user

However, they may do so more broadly than originally intended.

[00:00:43]

From a functional standpoint, they fit the existing model.

But naturally, that leads to a deeper and more important question:

If AI browsers qualify as user agents, what needs to change in that definition?

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Defining the User Agent

---

[00:01:20]

Let’s ground this discussion in the current definition.

A user agent is:

Software that interacts with other entities on behalf of its user.

This includes:

• Operating systems
• Email clients
• PDF and ebook readers
• Credential managers and digital wallets

A web user agent, more specifically, interacts with websites—even if it’s just rendering content.

[00:01:56]

That’s our baseline.

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Why This Question Matters

---

[00:02:01]

Now, when we talk about definitions, we’re really talking about standards and principles.

So the bigger question becomes:

What needs to evolve—not just in definitions, but in the foundational principles of the web?

This includes:

• Web Platform Design Principles
• Ethical Web Principles

[00:02:21]

The goal is to move from “mostly yes” to “obviously yes.”

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The Foundation: Priority of Constituencies

---

[00:02:49]

To unpack this, we need to revisit one of the web’s most important ideas: priority of constituencies.

This principle establishes a hierarchy:

• First: Users
• Second: Web page authors
• Third: Browser developers
• Fourth: Specification writers

[00:03:33]

This isn’t just philosophical—it actively shapes how the web is built.

Browsers, as user agents, are expected to:

• Prioritize user interests
• Act as protective intermediaries
• Enforce security and privacy boundaries

In short, browsers don’t just display the web—they help defend users.

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The Complication: AI Enters the Picture

---

[00:04:01]

However, AI changes things.

AI-enabled browsers introduce new capabilities, such as:

• Researching information autonomously
• Navigating services
• Performing tasks over time

This raises critical requirements:

• The browser must still protect the user
• Automation must not reduce safety
• Users must remain aware of actions taken

[00:04:34]

If these safeguards weaken, the browser shifts from user defender to automation tool.

That’s a major architectural change.

---

From Viewer to Actor

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[00:04:47]

Traditionally, browsers show the web.

Now, they may act within the web.

This creates two models:

• Passive: Displaying content
• Active: Acting on behalf of the user

[00:05:03]

While both fit the definition of a user agent, the second introduces new challenges:

• Governance
• Accountability
• Transparency

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The Rise of the User Proxy Model

---

[00:05:13]

One useful way to think about AI browsers is as user proxies.

Instead of simply exposing content, they represent the user.

This shift affects multiple stakeholders.

For Users

[00:05:30]

The browser must remain aligned with user intent.

However, delegation complicates this.

Consider:

• Is the browser acting for this user or an average user?
• Are actions influenced by company incentives?

For Websites

[00:05:59]

Websites face a different question:

Are browser actions equivalent to user actions?

For example:

• Is automated research normal browsing?
• Or is it bot-like behavior?

This is not theoretical—active discussions are happening around:

• AI behavior signaling
• Authentication of automated actors

---

The Role of Browser Developers

---

[00:07:02]

Browser developers sit in the middle of the ecosystem.

They translate principles into real systems.

Their decisions shape:

• User experience
• Security boundaries
• Permission models
• User control

[00:07:17]

AI introduces new pressures.

Developers must now answer:

• How transparent should automated actions be?
• What limits should exist on autonomy?
• How do permissions apply over time?
• How do we prevent unintended behavior?

These are no longer abstract—they are engineering challenges.

---

The Standards Perspective

---

[00:08:25]

At the end of the hierarchy are standards bodies.

Their role is to ensure:

• Interoperability
• Predictability
• Consistency across systems

With AI browsers, their work expands into:

• Identity and authentication
• Permission frameworks
• Accountability mechanisms
• Bot detection and automation policies

[00:09:14]

The challenge?

These areas are often siloed:

• Web standards groups
• Identity communities
• AI governance bodies

Each operates differently, with its own priorities.

---

A Collision of Ecosystems

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[00:09:47]

Today, nearly every standards organization is working on AI.

At the same time:

• Web groups focus on browser behavior
• Identity groups focus on credentials
• AI groups focus on models and governance

[00:10:06]

AI browsers sit at the intersection of all three.

This forces collaboration—whether the ecosystem is ready or not.

---

So, What Does This Mean?

---

[00:10:37]

On the surface, the shift seems small.

Browsers move from:

• Mediating interactions
• To acting within the ecosystem

But the implications are significant.

[00:10:53]

It challenges a core assumption:

That browsers reliably represent user interests.

---

Do We Need to Rewrite the Web?

---

[00:11:05]

Probably not.

The existing principles have worked well for decades.

They are:

• Strong
• Practical
• User-focused

[00:11:23]

However, we may need clearer guidance on applying them in an AI-driven world.

This could include:

• Stronger transparency expectations
• Clearer boundaries on delegated actions
• New ways to represent user intent

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Looking Ahead

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[00:11:50]

Many questions remain unanswered.

However, the key takeaway is this:

We need to ask these questions now.

Before AI browsers become so embedded that they are simply “browsers.”

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Final Thoughts and Call to Action

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[00:12:08]

This is the right moment to engage.

Consider:

• Joining standards discussions
• Participating in developer communities
• Exploring real-world implications

[00:12:22]

And if this topic interests you, check the full blog post for additional resources.

There’s more to come on AI in future episodes.

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Closing

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[00:12:41]

That’s it for this week’s episode of the Digital Identity Digest.

If this helped clarify things—or sparked new ideas—share it with a colleague.

Be sure to:

• Subscribe
• Leave a review
• Connect on LinkedIn

And as always:

Stay curious. Stay engaged. And keep the conversation going.