verify: whether the local simulator can be hosted on a2d-ai.com #279

What needs verifying

Whether the local gateway simulator (BG §1.4, #187) can additionally be
hosted on a2d-ai.com, and what that would require.

The vision deck raises this four times: the Phase 1 at-a-glance marks both the
simulator and the conformance plugin "maybe valid for A2D too", the examples
section titles the simulator slide "A governed gateway | A2D alternative", and
the simulator's design-rules slide lists it under "alternative and/or additive
path — investigate bringing this into a2d-ai.com; prototyping and mocking is
already hosted on a2d."

Concretely: can a2d-ai.com host an arbitrary HTTP mock service, can it serve
the captured rejection fixtures byte-identically, and can it emit the
x-donkey-simulator: true header #189 requires?

Why it blocks work

It does not block #187 — the pip-installable simulator ships regardless and
remains the supported path. It decides whether a hosted mode is in scope at
all, which affects #191's story for teams that cannot run a local server in CI.
Filed now so the answer exists before Phase 2 rather than being rediscovered
then.

Done when

• Confirmed whether a2d-ai.com can host the simulator, with the owning team
  named.
• If yes: the byte-identical-response and x-donkey-simulator constraints
  are confirmed satisfiable, and a scoping issue is filed against a phase.
• If no: recorded here as declined, with the reason, and the "maybe A2D
  too" framing is dropped from BG §1.4.
• No _verify.blocked(...) guard or docs/verified-apis.md row is added
  either way — this is a hosting question, not a gateway contract.

Related

• simulator: donkey mock — a local HTTP server that replays real rejection fixtures #187, simulator: the honesty guarantee — x-donkey-simulator header and a stock-client test #189, testing: the pytest plugin and the conformance suite customers run against their own agent #191