I think this may be the right form.
It solves the bargain with the reader almost exactly. The reader is warned at the threshold, then allowed to decide how much expansion to admit. Compression remains the default. Length is never imposed wholesale; it is elected locally. That matters because the whole thesis concerns aperture, frame, and what happens when widening outruns organization.
The form also makes a severe test possible. When a span expands and the surrounding text remains unchanged, the new material has nowhere to hide. It either sharpens the projected scene or it merely brightens the chamber. Ordinary long-form model prose often escapes judgment by continually rewriting its own premises. This would deny it that escape.
There is one obvious danger. Hypertext wants to become scholia. Click a phrase, receive an explanation, a gloss, a sidebar. That would miss the point. The click should behave like an aperture adjustment, not like a footnote. The expansion has to expose more of the same object while preserving the original line of sight. Once the click starts paraphrasing the sentence from above, the form has already collapsed into commentary.
Technically, the structure is clean. I would model the piece as a tree of spans. A rendered page is one cut through that tree at a given depth. Clicking a span replaces it with its child text, which may itself contain further expandable spans. That is simple enough for a first prototype: a JSON tree, a renderer that swaps nodes inline, and a small constraint layer governing compatibility. The deeper issue is not rendering but semantics. Sibling expansions should commute whenever possible. Expanding A and then B should yield the same text as B and then A if the spans are meant to belong to one essay rather than to alternative essays. When that cannot be made true, the interface should treat the branches as forks, not as independent clicks.
This suits a language instrument unusually well. Whole essays tempt the model into atmosphere. Span-local expansion gives it a bounded task. Used as an instrument, it can propose candidate child nodes. Used as a calculator, it can help test invariants: preserve the parent claim, add one necessary relation, recompress to a stronger sentence, avoid tonal drift, and respect neighboring expansions. The human operator remains the gateway to wider context, which is precisely the role your argument assigns to the human in relation to the machine. That is not a sentimental remainder. It is a structural one. The operator chooses aperture.
I would keep a few invariants hard. The root text must read as finished prose. Each expansion must sharpen rather than annotate. Surrounding text stays fixed unless a node is explicitly marked as a larger revision. Every intermediate state must still read continuously, as writing rather than as layered markup. And every branch must recompress to something stronger than the sentence or phrase that generated it. Without recompression, the tree will grow but the essay will not.
The strongest consequence of your unchanged-surroundings constraint is what it does to endings. A final sentence can be present from the root and remain untouched through every expansion. Its force then increases because the reader has widened the frame beneath it, not because the prose has cheated by rewriting its cadence. That seems exactly the awakening effect you were after: the piece comes crisply awake without changing its voice at the point of arrival.
Your camera obscura paragraph is already a good test case. The closing sentence could remain fixed: “Attention obeys the same geometry.” Earlier spans such as “aperture,” “context,” “operator,” or “image” could expand in place. If the form works, that final sentence should become more exact with each widening. If it does not, the failure will be visible immediately: the branch added language without changing what the sentence could see.
There is also a deeper fit between form and content. The essay would not merely describe multiscale rationality; it would enact it. Each click would be a controlled relaxation of closure. Each path would show how a local exactness survives, or fails, when admitted into a wider field. The reader would experience the argument as a sequence of aperture choices.
A good first experiment would be small and unforgiving: one paragraph, one fixed ending, three expandable spans, commuting branches only, and strict recompression at every level. That is enough to tell whether the form earns extension or merely disguises sprawl.