Why a small, closed verb set matters here specifically

How do we define and fill systemic gaps — what a genuinely enumerable protocol buys an analytical tool.

§"Protocol" in the research sense, made literal

In ordinary research method, a protocol is a fixed procedure written down precisely enough that someone else can follow it and expect the same outcome — a lab procedure, a coding scheme for qualitative analysis, a checklist for how evidence is logged. The word is used loosely by most software as "the API," but here the two meanings genuinely coincide: the literal HTTP contract is the fixed procedure, because everything the system can be made to do is already named, in advance, on the list in 5.3 — there is no informal, undocumented way to make it do something else.

§The gap: most tools' real capability outruns their documentation

A large enough system, built the ordinary way, tends to accumulate capability faster than anyone writes it down — undocumented parameters, side effects nobody meant to expose, behaviour reachable only by knowing an internal implementation detail. For an analytical platform this is a genuine liability, not just an inconvenience: if you cannot enumerate everything the system might have done to produce a result, you cannot fully audit how that result came to exist. Keeping the outward surface to three roads, and keeping every capability behind them named and registered rather than merely reachable, closes that gap directly — the list in 5.3 is not a curated subset of what is possible; the register is what is possible, because nothing gets a name without also getting an entry.

§Adding a capability is registration, not discovery

Because the surface is closed this way, extending it is a deliberate, visible act: one new row in the ingest register, or one new row in the projection register — never a capability that simply emerges from wiring things together informally. This mirrors, at the level of the whole system's outward face, exactly the same discipline Part 3 applies to one single fragment: nothing exists until it is declared, and the declaration itself is where anyone auditing the system later goes to find out what it can do.

§What a closed verb set does not protect against

None of this stops a badly designed capability from being registered and used — a poorly specified act can still be added to the ingest register and still do something unwise. What it protects is narrower and, again, exactly the thing worth protecting: that nothing the system does was ever reachable by an undocumented path. Every effect traces to a named entry someone can read, in full, in 5.3 — which is precisely what makes that list worth publishing whole rather than describing only in general terms.