…lback

…eadlineExpired and ResponseDropped.

…ed-inbound-responses

…ed-inbound-responses

…lbacks_with_enqueued_response invariant in CanisterQueues doc comment.

…ed-inbound-responses

…ry reject response that will result in a critical eror anyway (and the response being dropped).

… as a dummy canister ID.

Assign type parameters to canister queues and references, to designate them as either input/inbound or output/outbound.

Ensures that input queues can only hold inbound references; and output queues can only hold outbound references. Implements separate logic (for inbound and outbound references) for determining staleness, lookup and removal.

… the two specific `MessageStore<_>` implementations into `MessageStoreImpl`.

…t cleam-ups.

…nt when decoding CanisterQueue from proto.

…(but still CanisterInput by value for input queues).

…d to InboundReference / OutboundReference, to make it clear that the functions may panic (even though the two types are essentially private to the module).

…e item types declare their own context (inbound vs outbound) and use that when constructing a new reference of the given type.

Generate compact reject responses upon best-effort callback expiration. And inflate them into SYS_UNKNOWN reject responses when peeking/popping.

…eStore::callbacks_with_enqueued_response(); fix typo; move inner function definition before use.

…::is_stale() for better readability. Make all asserts for the right context type into debug_asserts().

…_response() and Reference::is_outbound_guaranteed_request() methods and use them to more concisely check for the respective message types.