fix(ts): refuse a temperature that is not a list of 3 at construction, as Python does (#502 parity) - #712

The arity-3 check is the right contract. laya/agent.py:451 refuses anything that is not a list or tuple of exactly 3, and 3 is what _decode_answers indexes, so this is parity rather than a new restriction on the TS side. I confirmed the default, the cfg path and the clamp ([100, 0, "2"] → [5, 0.5, 2]) are unchanged, that all four rejection cases in the new test fail on main, and that tsc --noEmit and the full suite are clean.

Two things to settle.

The error message does not match the Python it cites. Python raises:

Incompatible model: '/models/laya-english' temperature must be a list of 3 floats, got [1.3, 0.9]

and this raises:

Incompatible model: temperature must be a list of 3 floats, got [1.3,0.9]

The test asserts "Incompatible model: temperature must be a list of 3 floats" as a substring, but the model path sits between model: and temperature in the Python string, so that substring is not in it. The test therefore pins a message Python never emits. If the model id genuinely is not reachable from the constructor — it takes a provider, not a path — that is a fair reason not to match exactly, and providers.ts:308 and agent.ts:625 both interpolate one, so there may be an id within reach. Otherwise the assertion should be adjusted to the message this actually throws.

rawList.map reintroduces holes. Replacing [0, 1, 2].map((i) => clampTemperature(rawList[i] ?? 1.0)) with rawList.map(...) drops the guarantee that the result is dense, because Array.prototype.map skips holes. With temperature: new Array(3):

main:     length=3  hasOwnProperty(2)=true    temperature[2]=1        serialises [1,1,1]
this:     length=3  hasOwnProperty(2)=false   temperature[2]=undefined serialises [null,null,null]

Such a value passes the new arity check and then feeds undefined into the decode — the shape of failure #502 exists to prevent, arriving by a different route. It is not reachable from JSON, so it is narrow, but keeping the indexed form costs nothing:

this.temperature = [0, 1, 2].map((i) => clampTemperature(rawList[i]));

Worth noting that #710 and #711, from the same batch, take the opposite position on sparse holes and say so explicitly. This one moves the other way on the same hazard, which suggests it was not a deliberate choice.

Unrelated, but relevant to the parity claim: laya/onnx_agent.py:179 has no base-length check, only the language-override one at :190, so the two Python backends currently disagree with each other on this. Not a blocker here since the PR cites laya/agent.py and that is canonical — but "as Python does" is true of one backend and not yet of the other.