DRAFT / PROTOTYPE — opening this to evaluate the shape of the change. Builds on #27959 (bus eager-subscribe) and is orthogonal to #28187 (sync EffectBridge).

The problem

Today every sync.run produces two GlobalBus events with two different payload shapes:

1. From bus.publish itself — the projection view:

   { payload: { id, type: "session.created", properties } }
   

2. From sync/index.ts — the source-of-truth envelope:

   { payload: { type: "sync", syncEvent: { type: "session.created.1", id, seq, aggregateID, data } } }
   

Consumers discriminate via payload.type — either a real event type or the sentinel "sync". The two emits live in different files. The dual-emit is the source of "wait, which payload is this?" confusion.

History

• d88912abf0 (Dec 2025): Dax added GlobalBus.emit inside bus.publish.
• b22add292c (refactor(core): publish sync events to global event stream #22347, Apr 2026): James consolidated sync events onto GlobalBus by adding a second emit with the source envelope. Stated intent: "consolidate events into a single stream."

Two emits with different shapes on one channel isn't quite a single stream. One emit per event with a unified shape is.

What this PR does

Collapses the two emits into one:

{ payload: { id, type: "session.created", properties, sync?: { name, seq, aggregateID, data } } }

• bus.publish accepts an optional sync?: SyncMetadata option.
• sync/index.ts passes it; the second GlobalBus.emit is removed.
• BusEvent.effectPayloads() adds an optional sync field to every event schema.
• SyncEvent.effectPayloads() is no longer included in the wire schema (subsumed).
• Consumers migrate from payload.type === \"sync\" to payload.sync != null. workspace.ts reconstructs SerializedEvent from { id, sync.* } for replay.

Breaking change

This is a breaking SDK wire-format change. External consumers reading `payload.type === "sync"` or `payload.syncEvent` will need to migrate.

Inside opencode, all internal consumers were migrated in this PR:

• `cli/cmd/tui/context/event.ts`
• `cli/cmd/run/stream.transport.ts`
• `control-plane/workspace.ts`
• `app/src/context/global-sdk.tsx` (the web app)

Side-note: schema drift fixed

While doing this I noticed the runtime emit was using `payload.syncEvent` (nested) while the SDK schema (`SyncEvent.effectPayloads()`) declared the fields at top level under `type: "sync"`. They had drifted. Collapsing to one emit fixes this by definition.

Test plan

• `bun typecheck` from root — clean (all workspaces)
• `bun run test test/sync/index.test.ts test/bus/bus-effect.test.ts test/server/httpapi-event.test.ts test/server/httpapi-event-diagnostics.test.ts` — 29/29 green
• `bun run test test/server/httpapi-sdk.test.ts -t "streams sync-backed"` — green
• SDK regenerated via `packages/sdk/js/script/build.ts`

Net diff

~10 files. Includes regenerated SDK types.

Why draft

This is a wire-protocol change. Worth a deliberate decision on:

1. Whether the SDK breakage is acceptable now or needs coordination/version bump.
2. Whether the projection+envelope coupling is the right axis.
3. Whether to ship after fix(bus): acquire PubSub subscription eagerly to close /event race #27959 and refactor(sync): publish via EffectBridge.fork for codebase consistency #28187 land.

Happy to convert to ready-for-review or close, whichever you prefer.