feat(realtime): enhance RealtimeChannel type

[kakeluh]

What kind of change does this PR introduce?

infer payload type sent by realtime.broadcast_changes

What is the current behavior?

  on<{ record: Tables<"todos"> }>("broadcast", { event: "INSERT" }, ({ payload: { record } }) => {})

What is the new behavior?

  on<Tables<"todos">>("broadcast", { event: "INSERT" }, ({ payload: { record } }) => {})

Additional context

• https://supabase.com/docs/guides/realtime/subscribing-to-database-changes#using-broadcast
• https://github.com/supabase/realtime/blob/23a42553d43d5b4263b1436ab9850d7dea6b7602/lib/realtime/tenants/repo/migrations/20240919163303_add_payload_to_messages.ex#L29-L52

[Copilot]

Pull Request Overview

Enhances the RealtimeChannel typing so that broadcast payloads infer the record shape directly from the generic parameter.

• Introduces RealtimeBroadcast*Payload types with a shared base and specific insert/update/delete variants.
• Adds overloaded on<T> methods for BROADCAST events (ALL, INSERT, UPDATE, DELETE) returning strongly-typed payloads.

Comments suppressed due to low confidence (2)

src/RealtimeChannel.ts:441

• These new generic overloads and payload types should be covered by unit tests to ensure type inference works as expected and that events dispatch correct payload shapes.

on<T extends { [key: string]: any }>(

src/RealtimeChannel.ts:443

• For the ALL overload, the event field is typed as ALL but at runtime the payload.event will be the specific INSERT/UPDATE/DELETE. Update the type to a union of specific events or rename to avoid misleading consumers.

filter: { event: REALTIME_POSTGRES_CHANGES_LISTEN_EVENT.ALL },

[Copilot]

[nitpick] RealtimeBroadcastChangesPayloadBase overlaps with RealtimePostgresChangesPayloadBase (schema/table). Consider merging shared fields or extending one from the other to reduce duplication.

Suggested change

	type RealtimeBroadcastChangesPayloadBase = {
	id: string
	schema: string
	table: string
	}
	type RealtimeChangesPayloadBase = {
	schema: string
	table: string
	}
	type RealtimeBroadcastChangesPayloadBase = RealtimeChangesPayloadBase & {
	id: string
	}

[Copilot]

[nitpick] Using T extends { [key: string]: any } is very loose. Consider constraining to Record<string, unknown> or a more specific shape to improve type safety.

Suggested change

	on<T extends { [key: string]: any }>(
	on<T extends Record<string, unknown>>(

[Copilot]

[nitpick] The multiple overloads for broadcast events are largely repetitive. You could consolidate them using a single overload with conditional types on filter.event to reduce duplication.