") " wrapping a " (code "
") " before the actual content. The tree structure " (em "is") " the semantic structure. Every node is either content or control, and the distinction is syntactically obvious: controls have " (code "sx-") " attributes, content does not.")
- (p :class "text-stone-600"
- "And unlike JSON hypermedia, the AI does not need to understand a media type specification to interpret the controls. The controls are HTML-like elements with method and target attributes — a pattern every LLM already understands from training on web content. SX inherits the discoverability of HTML (controls are self-describing) without the noise (no closing tags, no attribute soup, no CSS class archaeology).")
- (p :class "text-stone-600"
- "The " (a :href "/sx/(etc.(essay.sx-and-ai))" :class "text-violet-600 hover:underline" "spec fits in a context window") ". The complete SX language — evaluator, parser, renderer, all primitives — is roughly 3,000 lines. An AI agent that loads the spec into its context can not only read SX responses but " (em "generate") " them. It can produce new pages, new components, new interactions — because the language it reads and the language it writes are the same, and both fit in memory at once."))
+ "In an SX hypermedia system, the controls in the response " (em "are") " the capability. Not a description of capability. Not a pointer to capability. The control itself — its structure, its attributes, its evaluable URL — carries everything needed to act on it. And the rules for interpreting the control are carried by the same language the control is written in. There is no indirection. There is no separate layer where meaning must be maintained. The response means what it says, and it says what it means, because it carries its own interpreter."))
- (~docs/section :title "VIII. What MCP gets wrong" :id "mcp"
+ (~docs/section :title "VIII. There is only the hypermedium" :id "the-hypermedium"
(p :class "text-stone-600"
- "MCP's design reflects a fundamental confusion: it treats capability as a catalogue rather than an affordance. The server lists every tool. The model reads the list. The model calls a tool. The response is data. The model must maintain its own mental model of the server's state to know which tools are appropriate next.")
+ "The hypermedia discourse frames the question as a competition between formats: HTML vs JSON, server-rendered vs client-rendered, REST vs RPC. Blow adds a new axis — human clients vs AI agents — and asks which format serves both. These are all the wrong questions. They assume that hypermedia is a property that a format can have in greater or lesser degree, and the task is to find the format with the most of it.")
(p :class "text-stone-600"
- "This is the exact inversion of the hypermedia principle. In a hypermedia system, the server tells you what you can do " (em "in each response") ". You do not need a mental model of the server because the server renders its own state into the controls it offers you. Following controls is safe because the server would not offer a control that is not valid right now.")
+ "Hypermedia is not a spectrum. It is a threshold. Either a format can define its own interpretation, or it cannot. If it cannot, it depends on external meaning — an RFC, a browser engine, a media type specification — and that dependency makes it something less than a " (em "medium") ". A medium is self-sustaining. It does not require a separate system to explain what it is. Sheet music is a medium because a musician can read it and produce sound. A JSON object with " (code "\"type\": \"sheet-music\"") " is not a medium. It is data that requires a separate program, written in a separate language, consulting a separate specification, to become anything at all.")
(p :class "text-stone-600"
- "SX pages embody this principle. Each response contains exactly the controls that are available from the current state. The server evaluates the conditions — " (code "can-cancel") ", " (code "can-refund") ", " (code "shipped") " — and renders only the applicable controls. The client, human or AI, does not need to reason about what is possible. It just reads what is offered.")
+ "By this criterion, HTML is not hypermedia. It is the closest the web has come — close enough that the browser's deep internalization of the spec creates the " (em "illusion") " of self-interpretation. But the illusion breaks the moment you step outside the browser. Give HTML to a new client — an AI agent, a screen reader, a search crawler — and that client must reimagine the spec from training data, heuristics, and hope. The meaning was never in the HTML. It was in the browser.")
(p :class "text-stone-600"
- "This is why the htmx camp's insistence on HTML hypermedia is not mere nostalgia. The principle is correct: the server should author the interaction. Where htmx falls short is in choosing a format that is optimized for human visual consumption at the expense of machine interpretability. SX resolves this by using a format that is equally transparent to both — because s-expressions are the " (em "simplest possible") " structured representation, and simplicity is readable by anything."))
-
- (~docs/section :title "IX. Beyond the format wars" :id "beyond"
+ "JSON is not hypermedia and never will be, no matter how many link relations you attach to it. The meaning is always elsewhere.")
(p :class "text-stone-600"
- "The deeper issue with the \"JSON vs HTML for hypermedia\" debate is the assumption that content and control are separate concerns that a format must somehow reunite. HTML reunites them through rendering semantics. JSON formats try to reunite them through metadata conventions. Both accept the premise that there are two things — data and interaction — and the question is how to ship them together.")
+ "There is only the hypermedium: a representation that defines its own interpretation. A representation where the spec is written in the language, and the spec " (em "is") " the language — executable, bootstrappable, self-sustaining. S-expressions are not the only possible instance of this. Any homoiconic, metacircular language could satisfy the criterion. But s-expressions are the simplest. The minimal syntax — " (code "(head args...)") " — is the minimal overhead between a format and self-definition. McCarthy arrived at this in 1958. It has taken sixty-eight years for the rest of computing to need it.")
(p :class "text-stone-600"
- "S-expressions reject the premise. In a homoiconic language, data and code are the same thing. A list that describes a button is also an instruction to render a button. A list that describes a link is also a navigable reference. The component that renders an order card " (em "is") " the order card. There is no gap between the representation and the thing represented because the representation is executable.")
+ "The age of AI makes the need urgent. When your clients are no longer just browsers with built-in specs but arbitrary agents that must learn interpretation on the fly, a format that carries its own interpreter is not a luxury. It is the only thing that works. Not because it is clever. Because everything else depends on meaning that lives somewhere else — and " (em "somewhere else") " is the one place an ad-hoc agent cannot be guaranteed to look.")
(p :class "text-stone-600"
- "This is what Blow is reaching for when he says resources should be state machines with hyperlinks as transitions. He is describing a system where the response does not merely " (em "describe") " the available transitions but " (em "enacts") " them — where clicking a link is not interpreting a JSON object but following a control that the server authored into the response. HTML does this for humans. SX does this for both humans and machines. And SX does it with a grammar so minimal that generating it is nearly trivial for any system that can produce structured text.")
- (p :class "text-stone-600"
- "The age of AI does not need a new hypermedia format. It needs to notice that the oldest structured notation in computing — McCarthy's parenthesized lists from 1958 — already solves the problem. Content, control, code, in one syntax, readable by anything, generable by anything, evaluable anywhere. The true hypermedium was " (a :href "/sx/(etc.(essay.self-defining-medium))" :class "text-violet-600 hover:underline" "always already here") "."))))
+ "SX represents the hypermedium. Not a new format in the format wars. Not a better JSON. Not a simpler HTML. The thing itself — a representation that " (em "means what it says") " because it carries the rules for saying it."))))