Runtime v2 implementation notes

Archived on 2026-07-13. These notes describe the initial Phase 1–4 skeleton; the backend architecture chapters and current source now describe the active runtime.

Status: Phase 1–4 skeleton landed (compile-safe, tested). The production SessionManager.sendMessage hot path is unchanged; the v2 seam exists in parallel so future work can migrate onto it incrementally.

Source plan: docs/archive/runtime-v2-architecture-evolution.md.

What landed

Core contract (@maka/core)

• packages/core/src/runtime-event.ts — the canonical RuntimeEvent fact model (role / author / status enums, content discriminated union, actions, refs, pure helpers isTerminalRuntimeEvent / runtimeEventHasModelVisibleContent / createRuntimeEventId).
• packages/core/src/__tests__/runtime-event.test.ts — focused contract tests.
• New subpath export @maka/core/runtime-event. The later public-API cleanup removed the package root barrel, so this subpath is now the only public route.

Runtime v2 seam (@maka/runtime)

Five new modules, each importable via its canonical subpath AND re-exported (selectively) from the runtime barrel:

Module	Subpath	Role
model-history.ts	@maka/runtime/model-history	Policy-driven buildModelHistoryFromRuntimeEvents() replacing ad-hoc StoredMessage filtering.
invocation-context.ts	@maka/runtime/invocation-context	InvocationRequest / InvocationContext spine, injectable newId/now providers, InvocationResult envelope.
runtime-runner.ts	@maka/runtime/runtime-runner	RuntimeRunner.run() collecting shell: preflight gate → context → user event → flow dispatch → terminal collection.
agent-flow.ts	@maka/runtime/agent-flow	Formal AgentFlow / AgentFlowControl / FlowInput seam.
ai-sdk-flow.ts	@maka/runtime/ai-sdk-flow	AiSdkFlow wrapping an AgentBackend; mapSessionEventToRuntimeEvent() placeholder mapping.

Each module shipped with co-located tests for the initial migration seam.

Exports consolidated by the steward

• packages/core/package.json — added "./runtime-event".
• packages/runtime/package.json — added the runtime-v2 subpath exports.
• The later public-API cleanup removed both package root barrels in favor of explicit domain subpaths.

Reconciled: single InvocationContext type

InvocationContext is now owned by invocation-context.ts and reused by the formal flow seam:

• invocation-context.ts — the canonical runner/flow spine (required source, startedAt, request, newId, now).
• agent-flow.ts — imports and re-exports that canonical type for the AgentFlow.run(ctx, input) contract.

The runtime barrel re-exports the canonical InvocationContext from invocation-context.ts; the previous duplicate flow-local context was removed so runner and flow code share the same identity/provider spine.

What remains (by phase)

• Phase 5 — Tool-event actions: promote tool_output_delta / tool_progress SessionEvents to a dedicated tool-progress runtime action (currently partial tool-role heartbeats). Refine mapSessionEventToRuntimeEvent role/author policy.
• Phase 6 — RuntimeGate: implement the real preflight (connection readiness/rebind, blocked/running/waiting guards) behind RuntimeGate and inject it into desktop + bot/gateway entrypoints.
• Phase 7 — Projection: drive StoredMessage / TurnRecord / SessionHeader / AgentRunStore / RunTrace / TelemetryRepo writes from InvocationResult.events. Wire buildModelHistoryFromRuntimeEvents() into the live AiSdkBackend.materializePriorMessages path.
• SessionManager delegation: replace the body of SessionManager.sendMessage with RuntimeRunner.run(...) behind a feature flag, mapping InvocationResult.events → existing SessionEvent projection. A streaming async *stream() variant may be added then if the renderer needs live deltas. Today RuntimeRunner.run() is collecting (returns Promise<InvocationResult>), not streaming.
• abort + complete coalescing: AiSdkFlow is a faithful translator (the backend emits abort then a trailing complete, and the flow emits both). Coalescing into a single terminal event is a runner/projection concern.
• Flow runnable surface: RuntimeRunner depends on the centrally owned RunnableAgentFlow (Pick<AgentFlow, 'run'>) so it remains decoupled from flow metadata (kind, sessionId) while sharing the formal AgentFlow.run signature.

Verification snapshot

All commands run from the repository root ($RIVE_WORKSPACE):

npm run build                                    # all workspaces — clean
npm run typecheck                                # all workspaces — clean
npm --workspace @maka/core   run test            # 613 pass / 0 fail
npm --workspace @maka/runtime run test           # 384 pass / 0 fail
git diff --check                                 # clean

No production source (session-manager.ts, ai-sdk-backend.ts, agent-run.ts, materializer.ts) was modified. The v2 seam is purely additive.