198 pointfree choke claims no stage

// The wall that keeps 210_197's per-stage choke filter honest.
//
// 210_197 lets a choke replicate only onto the stages that DECLARE it — which
// is what a heterogeneous ladder needs, and which on its own would let a
// MISTYPED choke vanish: filtered out at every stage, silently dropped, and
// the branch it meant to claim left to fail a few lines away as "unhandled".
//
// So the exactness check moves up a level, to where it always belonged: a
// choke must be claimed by AT LEAST ONE stage of the chain. `| out-of-rang`
// below names nothing in `obj.get`, `arr.get` or `as.string`, and is refused
// AT THE CHOKE — not as a distant KORU022 about `out-of-range`.
//
// Pins KORU021 with a chain-scoped message.
~import std/io

~pub tor obj.get { doc: i64, v: i64, key: string }
| found i64
| not-found
~proc obj.get|zig { _ = doc; _ = key; return .{ .found = v + 1 }; }

~pub tor arr.get { doc: i64, v: i64, index: i64 }
| found i64
| out-of-range
~proc arr.get|zig { _ = doc; _ = index; return .{ .found = v + 1 }; }

~pub tor as.string { doc: i64, v: i64 }
| ok string
| wrong-type
~proc as.string|zig { _ = doc; _ = v; return .{ .ok = "deep" }; }

~pub tor ladder { doc: i64, r: i64 }
| ok string
| gone
~ladder = obj.get(doc, v: r, key: "choices")
  |> arr.get(doc, index: 0)
  |> as.string(doc)
| not-found => gone
| out-of-rang => gone
| wrong-type => gone

~ladder(doc: 1, r: 2)
| ok s |> std/io:print.ln("{{ s:s }}")
| gone |> std/io:print.ln("gone")