The Address String Form

The rule: Address.ToString(), Address.ToFullString(), the implicit string conversion and the JSON AddressConverter all write ONE form: outermost_host~…~host~path. For an unhosted address that is just its Path. The implicit string → Address parser reads that same form back, so (Address)address.ToString() equals address, including nested hosts.

Why this needed fixing (#6604)

Until #6604, ToString() rendered path~host, but the parser splits on the FIRST ~ and treats the left side as the host. Every key minted with ToString() and then parsed back therefore came back REVERSED. sync/g~ui/c became ui/c hosted on sync/g. The keys that do this round trip are:

• the IPodHubGrain key. PodHubGrain turns its primary key into an Address (Address address = AddressPath) and looks up the local route with it.
• a MessageHubGrain key, resolved by GetAddress(key) on activation.

Neither raised an error. The pod-hub grain simply looked up the wrong local route, answered PodHubNotHere, and the router fell back.

The parser, the wire serializer, AccessContext.ObjectId and UserNodeType.IsPortalIdentity all used host~path already. ToString() was the outlier, and it now delegates to ToFullString().

Rules for callers

• Want the node path? Use Address.Path. The host chain says where an address is activated, not what it is. Never split ToString() to find a path or a type. Address.Type is Segments[0].
• A segment holds neither / nor ~. Both are structural in the string form. A node id that could contain ~ is escaped before it becomes a segment (AppDirectory encodes ~ as ~7E). A raw ~ in a segment cannot round-trip, and the parser will read it as a host separator.
• Exact equality round-trips only when no segment holds /. Production does build such addresses: KernelContainer writes new Address("kernelExec", hub.Address.Path), a whole path in ONE segment. Its string is the same text, and it parses back with the same Path, Type and host chain, but re-segmented (kernelExec, activity, x, y instead of kernelExec, activity/x/y), so Address.Equals is false. StreamRoutingHotPathTest pins that shape as production behaviour. So the guarantee is: ToString() and parsing agree on Path and on the host chain for every address, and on Equals for an address whose segments hold no /. Compare a key that may carry an embedded / by Path (or by its string), never by Equals against a parsed copy.

The one text that crosses a roll

Grain keys and memory-stream ids are in-memory only, so nothing persisted used the old form. The one cross-process TEXT that did is the shutdown banner, Hub {subject} is shutting down, inside a NACK message. During a roll an old pod's NACK is read by a new pod. So:

• ShutdownNack.Banner writes the owner's Path as the subject, with no host chain.
• ShutdownNack.IsAnsweredByOwner reads a subject up to its first ~. A banner from this release has no ~. A banner from the previous release had path~host, and its path is the part before the first ~.

Where it is pinned

• AddressStringRoundTripTest (MeshWeaver.Messaging.Hub.Test): seeded property test over one to four segments and zero to three nested hosts. It checks the parse round trip and that the wire form agrees. A negative control shows the old rendering does not round-trip. AnEmbeddedSlash_KeepsPathAndHost_ButNotSegmentation pins the narrower guarantee for a segment that holds /.
• OwnerAnswerRecognitionGuard.ABannerFromThePreviousRelease_IsStillRecognised (MeshWeaver.Hosting.Test): the roll window.