feat(durable-messaging): add envelope and routing contracts - #11282

Problem

Durable Messaging needs shared envelope, routing and handler contracts so inbox, outbox and hosting can be reviewed as focused layers.

Solution

Provide serialized envelopes, hierarchical correlation keys, delivery outcomes, validated options, inbox/outbox interfaces and typed handler-routing helpers in the eventual Microsoft.Orleans.DurableMessaging assembly.

Outgoing messages use explicit preparation before shared state changes. IDurableOutbox.PrepareSendAsync(IReadOnlyList<DurableEnvelope>, CancellationToken) copies and validates outgoing intents and acquires their durable wakeup prerequisite. It returns an opaque, activation-local IPreparedOutboxBatch : IDisposable; synchronous Send(IPreparedOutboxBatch) stages the prepared output.

Handlers use PrepareAsync -> ValueTask<Action>: await preparation through context.Outbox, then apply complete business mutations and send the batch from the matching synchronous action. Ordinary callers await each preparation and retain/dispose its batch through the mutation and ordinary journal-write scope. Runtime layers own started acquisitions, late results, actual persistence outcomes and delivery eligibility. Duplicate sends coalesce within their valid scope; caller cancellation preserves owned scheduling through completion.

Rationale and scope

Preparation, synchronous safe-to-commit updates and ordinary atomic journal writes keep application policy with its owner. The Journaling foundation retains its established public API and capture/replay/reset/acknowledgement protocol. A failed initial recovery completes that attempt with its original error and leaves the manager uninitialized. A subsequent explicit InitializeAsync resets and replays the existing instances from the beginning; writes become available after successful recovery. One lifetime work-loop task handles recovery attempts and persistence. After a failed attempt, that same task waits for a queued explicit initialization request; stale signals are consumed while it waits. Initialization admission and owner shutdown are serialized under the manager lock. Registration stays closed after initialization begins, and admitted persistence failures retain terminal handling. Feature owners handle failed writes and cleanup directly. Deletion follows the explicit owner workflow: stop and drain messaging, await actual journal deletion, then dispose or deactivate; subsequent work uses a fresh owner.

This intermediate project stays non-packable while runtime and hosting are assembled. Envelope aliases/member IDs, routing, payload metadata and the DeliverAsync wire manifest are preserved. Contract tests retain the external-consumer boundary and exercise internal adapters through public interfaces and reflection.

Depends on #11326 at 901d42432a8e7daa1308aa7a232f02e3f1adc67a, based on selected main 0bfd95e8561699b3bb7c619b0b0d2378d84395bc. Published head: fb911fa47667b91215371d9f43298c5178619de0; all eleven contracts commits remain equivalent. Review the immutable incremental diff. Inbox, outbox and final composition follow in #11284, #11285 and #10693.

Microsoft Reviewers: Open in CodeFlow