decompose architecture into 38 atomic tasks across 12 parallel generations

Decompose the reviewed architecture specs into taskgraph-managed tasks:
- 2 setup tasks (project init, test infrastructure)
- 4 schema tasks (enums, node attrs, edge attrs, graph schemas)
- 1 error hierarchy task
- 6 graph tasks (FlowGraph class, 3 construction paths, queries, validation)
- 5 analysis tasks (type-compat, build-type-edges, ordering, template-validation, defaults)
- 5 component tasks (Operation, Sequential, Parallel, Conditional, Map)
- 2 host config tasks (GraphologyHostConfig, ReactiveHostConfig)
- 4 reactive tasks (WorkflowRoot, node-status, max-concurrency, retry-semantics)
- 3 review tasks (foundation, reactive-and-hosts, complete-library)
- 5 meta cluster tasks (schema, graph, component, reactive, analysis layers)
- 1 API exports task

Validated with taskgraph: zero cycles, 38 tasks, 12 parallel generations.
Critical path: 12 tasks through reactive execution layer.

tasks/reactive-node-status.md

@@ -0,0 +1,42 @@
+---
+id: reactive/node-status
+name: Implement node status signal management and computed preconditions + blockedByFailure
+status: pending
+depends_on:
+  - reactive/workflow-root
+  - schema/enums
+scope: moderate
+risk: high
+impact: component
+level: implementation
+---
+
+## Description
+
+Implement the reactive node status management layer: `signal<NodeStatus>` per-node lifecycle tracking, `computed<boolean>` precondition resolution, `computed<boolean>` blockedByFailure detection, and the effects that wire them together to drive automatic state transitions.
+
+## Acceptance Criteria
+
+- [ ] `src/reactive/node-status.ts` exports precondition computation, blockedByFailure computation, and status transition effects
+- [ ] `computePreconditions(node, ctx): boolean` — Sequential: previous sibling completed/skipped; Parallel: parent preconditions met; Conditional: condition evaluates; root nodes: true (no predecessors)
+- [ ] `computeBlockedByFailure(node, ctx): boolean` — any predecessor is failed/aborted
+- [ ] Start effect: `if (preconditions.value && (status === "idle" || "waiting")) → transition to "ready"`
+- [ ] Abort effect: `if (blockedByFailure.value && (status === "idle" || "waiting")) → transition to "aborted"`
+- [ ] `skipped` satisfies preconditions — a skipped predecessor is treated as "completed for precondition purposes"
+- [ ] `failed` and `aborted` block preconditions — dependents can never become ready
+- [ ] Failure follows dependency edges, not structural scope — sibling branches in Parallel are independent
+- [ ] Effects are tracked by `WorkflowReactiveRoot.effectDisposers` and cleaned up by `dispose()`
+- [ ] Unit tests: sequential preconditions, parallel preconditions, join (fork-join) preconditions, blockedByFailure cascade, skipped satisfies preconditions, failure isolation in parallel branches
+
+## References
+
+- docs/architecture/reactive-execution.md — computed preconditions, blockedByFailure, status propagation effects, failure isolation
+- docs/architecture/host-configs.md — WorkflowNode, prerequisite computation
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion