feat(core): engine run loop (1.N) + built-in ToolRegistry (1.T)

CLAUDE.md

@@ -48,8 +48,10 @@ ADR-0030 seam-shape amendment — and the **ADR-0031 multimodal seam-shape amend
 reserved generator methods, shape-only, landed before the seam's exhaustive consumers. The
 `FallbackChain` runner (1.K, PR #13) is now landed and fully covered. The
 [`@relavium/core` engine](docs/roadmap/phases/phase-1-engine-and-llm.md) lane has since landed the
-**`WorkflowYAMLParser` (1.L, PR #14)** and the **`{{ … }}` interpolation engine + parse-time secret-taint
-gate (1.L2, PR #15)**; active work continues with the **DAG builder + `RunPlan` (1.M)**; see
+**`WorkflowYAMLParser` (1.L, PR #14)**, the **`{{ … }}` interpolation engine + parse-time secret-taint
+gate (1.L2, PR #15)**, and the **DAG builder + `RunPlan` (1.M)** plus the **QuickJS-wasm expression
+sandbox (1.AB)** (PR #16, 2026-06-13); active work continues with the **run loop — `WorkflowEngine` +
+`RunEventBus` (1.N)**; see
 [docs/roadmap/current.md](docs/roadmap/current.md). See [README.md](README.md) for the public overview.
 
 ## Non-negotiable rules for AI agents

README.md

@@ -38,8 +38,9 @@ vendor type crossing it (PR #7–#9), followed by the **ADR-0031 multimodal seam
 reserved generator methods, landed **shape-only** before the seam's exhaustive consumers exist
 (PR #11, 2026-06-10). The seam's last policy layer — the `FallbackChain` runner (1.K) — then landed
 (PR #13, 2026-06-11), completing the LLM lane. The `@relavium/core` engine lane has since landed the
-**`WorkflowYAMLParser`** (1.L, PR #14) and the **`{{ … }}` interpolation engine + parse-time
-secret-taint gate** (1.L2, PR #15) — both with zero platform imports. Next on the critical path: the
-**DAG builder + `RunPlan`** (1.M), then the run loop, checkpoint/resume, and retry, plus the
+**`WorkflowYAMLParser`** (1.L, PR #14), the **`{{ … }}` interpolation engine + parse-time
+secret-taint gate** (1.L2, PR #15), and the **DAG builder + `RunPlan`** (1.M) together with the
+**QuickJS-wasm expression sandbox** (1.AB) (PR #16, 2026-06-13) — all with zero platform imports.
+Next on the critical path: the run loop (1.N), then checkpoint/resume and retry, plus the
 **AgentSession** runtime + export-to-workflow sub-spine. See
 [docs/roadmap/current.md](docs/roadmap/current.md) for live status.

docs/architecture/execution-model.md

@@ -138,10 +138,18 @@ After every node completes, the engine writes a checkpoint to local SQLite — r
 status, per-node states, completed and pending node IDs, and (for an orchestrator)
 its message history. This is the foundation for resume and retry; see
 [shared-core-engine.md](shared-core-engine.md#checkpoint-and-resume). There is **no separate
-checkpoint table** — the checkpoint is reconstructed (by a `Checkpointer`) from `step_executions`
-+ `run_events` (+ `messages` for an orchestrator's history), all defined in
+checkpoint table** — the checkpoint is reconstructed (by a `Checkpointer`) from `step_executions`,
+`run_events` (and `messages` for an orchestrator's history), all defined in
 [../reference/desktop/database-schema.md](../reference/desktop/database-schema.md).
 
+Three run-loop substrate rules make this reliable ([ADR-0036](../decisions/0036-run-loop-substrate-event-bus-and-execution-host.md)):
+a node-boundary / terminal event is **persisted before it is delivered** to consumers, so a crash
+between emit and write can never re-run a completed node or lose its output; the
+**monotonic, gap-free `sequenceNumber` is assigned at a single producer-side point** (one counter per
+run/session), so concurrent fan-out branches cannot duplicate or invert numbers; and gate / run
+`timeout_ms` deadlines are armed as **one-shot timers from an injected clock — not a sleep/poll loop**,
+so the completion-driven scheduler stays event-driven.
+
 ### 6. Finish
 
 On the last node the engine writes the final output and a cost record to SQLite,

docs/architecture/shared-core-engine.md

@@ -85,9 +85,10 @@ The artifact contracts it consumes and produces live in
   [../standards/architectural-principles.md](../standards/architectural-principles.md).) See
   [../reference/shared-core/built-in-tools.md](../reference/shared-core/built-in-tools.md)
   and [../reference/shared-core/mcp-integration.md](../reference/shared-core/mcp-integration.md).
-- **`RunEventBus`** — an `EventEmitter` that carries the typed run events
-  surfaces subscribe to. The event contract is the
-  [SSE event schema](../reference/contracts/sse-event-schema.md).
+- **`RunEventBus`** — an in-house, **platform-free** typed event bus (pub/sub) over the `RunEvent`
+  union that surfaces subscribe to. It is built in `packages/core`, **not** Node's `node:events` (the
+  engine has zero platform imports — [ADR-0036](../decisions/0036-run-loop-substrate-event-bus-and-execution-host.md)).
+  The event contract is the [SSE event schema](../reference/contracts/sse-event-schema.md).
 
 ## YAML → DAG compilation