feat: implement node status signal management with computed preconditions and blockedByFailure

- Add computePreconditions and computeBlockedByFailure functions to node-status.ts
- Add registerStartEffect and registerAbortEffect for automatic state transitions
- Start effect: idle/waiting -> ready when preconditions met
- Abort effect: idle/waiting -> aborted when blockedByFailure true
- Refactor WorkflowReactiveRoot to use node-status.ts functions
- Root nodes auto-transition from idle to ready (no predecessors = preconditions true)
- Add AbortEffectOptions with abortDependents policy support
- Add comprehensive unit tests for all precondition and failure isolation scenarios

src/analysis/index.ts

@@ -4,7 +4,7 @@ export {
   defaultEdgeType,
   resolveDefaultNodeAttrs,
 } from "./defaults.js";
-export { typeCompat, type TypeCompatResult, type TypeMismatch } from "./type-compat.js";
+export { typeCompat, buildTypeEdges, type TypeCompatResult, type TypeMismatch } from "./type-compat.js";
 export {
   topologicalOrder,
   parallelGroups,
@@ -13,9 +13,9 @@ export {
   ancestors,
   descendants,
 } from "./ordering.js";
-export { buildTypeEdges } from "../graph/construction.js";
 export {
   validateSchema,
   validateGraph,
   validate,
-} from "../graph/validation.js";
+} from "../graph/validation.js";
+export { validatePreconditions, validateTemplate } from "./workflow.js";

src/analysis/type-compat.ts

@@ -1,4 +1,11 @@
 import { KindGuard, Kind, type TSchema } from "@alkdev/typebox";
+import { willCreateCycle } from "graphology-dag";
+import type { FlowGraph } from "../graph/construction.js";
+import {
+  OperationNodeAttrs as OperationNodeAttrsSchema,
+  OperationEdgeAttrs as OperationEdgeAttrsSchema,
+} from "../schema/index.js";
+import type { OperationNodeAttrs } from "../schema/index.js";
 
 export interface TypeMismatch {
   path: string;
@@ -275,4 +282,25 @@ export function typeCompat(outputSchema: TSchema, inputSchema: TSchema): TypeCom
   }
 
   return { compatible: false, mismatches };
+}
+
+export function buildTypeEdges(graph: FlowGraph<typeof OperationNodeAttrsSchema, typeof OperationEdgeAttrsSchema>): void {
+  const nodeKeys = graph.nodes();
+  for (const source of nodeKeys) {
+    for (const target of nodeKeys) {
+      if (source === target) continue;
+      const sourceAttrs = graph.getNodeAttributes(source as never) as unknown as OperationNodeAttrs;
+      const targetAttrs = graph.getNodeAttributes(target as never) as unknown as OperationNodeAttrs;
+      const result = typeCompat(sourceAttrs.outputSchema as TSchema, targetAttrs.inputSchema as TSchema);
+      if (result === undefined) continue;
+      if (graph.hasEdge(source, target)) continue;
+      if (willCreateCycle(graph.graph, source, target)) continue;
+      const detail = result.detail ?? `${sourceAttrs.namespace}.${sourceAttrs.name}.output → ${targetAttrs.namespace}.${targetAttrs.name}.input`;
+      graph.addTypedEdge(source, target, {
+        compatible: result.compatible,
+        detail,
+        ...(result.mismatches !== undefined ? { mismatches: result.mismatches } : {}),
+      });
+    }
+  }
 }

src/analysis/workflow.ts

@@ -1 +1,197 @@
-export {};
+import type { TSchema } from "@alkdev/typebox";
+import { KindGuard } from "@alkdev/typebox";
+import type { UNode } from "@alkdev/ujsx";
+import { createHostRoot } from "@alkdev/ujsx";
+import { hasCycle } from "graphology-dag";
+import { DirectedGraph } from "graphology";
+import type { FlowGraph } from "../graph/construction.js";
+import type { OperationNodeAttrs } from "../schema/node.js";
+import type { OperationEdgeAttrs } from "../schema/edge.js";
+import type { ValidationError, AnyValidationError } from "../error/index.js";
+import { GraphologyHostConfig } from "../host/graphology.js";
+import { reachableFrom } from "../graph/queries.js";
+
+function getRequiredTopLevelFields(schema: unknown): Set<string> {
+  const fields = new Set<string>();
+  if (schema === null || schema === undefined || typeof schema !== "object") return fields;
+  const s = schema as TSchema;
+  if (!KindGuard.IsObject(s)) return fields;
+  const props = s.properties as Record<string, TSchema> | undefined;
+  const required = s.required as string[] | undefined;
+  if (props && required) {
+    for (const key of required) {
+      fields.add(key);
+    }
+  }
+  return fields;
+}
+
+function getProvidedFields(schema: unknown): Set<string> {
+  const fields = new Set<string>();
+  if (schema === null || schema === undefined || typeof schema !== "object") return fields;
+  const s = schema as TSchema;
+  if (!KindGuard.IsObject(s)) return fields;
+  const props = s.properties as Record<string, TSchema> | undefined;
+  if (props) {
+    for (const key of Object.keys(props)) {
+      fields.add(key);
+    }
+  }
+  return fields;
+}
+
+export function validatePreconditions(
+  graph: FlowGraph<typeof import("../schema/node.js").OperationNodeAttrs, typeof import("../schema/edge.js").OperationEdgeAttrs>,
+): ValidationError[] {
+  const errors: ValidationError[] = [];
+  const nodeKeys = graph.nodes();
+
+  for (const nodeKey of nodeKeys) {
+    const attrs = graph.getNodeAttributes(nodeKey) as unknown as OperationNodeAttrs;
+    const inputSchema = attrs.inputSchema;
+    const requiredFields = getRequiredTopLevelFields(inputSchema);
+
+    if (requiredFields.size === 0) continue;
+
+    const predecessors = graph.predecessors(nodeKey);
+    if (predecessors.length === 0) {
+      for (const field of requiredFields) {
+        errors.push({
+          type: "schema",
+          nodeKey,
+          field,
+          message: `Required input field "${field}" has no predecessor providing it`,
+        });
+      }
+      continue;
+    }
+
+    const providedFields = new Set<string>();
+    for (const predKey of predecessors) {
+      const predAttrs = graph.getNodeAttributes(predKey) as unknown as OperationNodeAttrs;
+      const predProvided = getProvidedFields(predAttrs.outputSchema);
+      for (const field of predProvided) {
+        providedFields.add(field);
+      }
+    }
+
+    for (const field of requiredFields) {
+      if (!providedFields.has(field)) {
+        errors.push({
+          type: "schema",
+          nodeKey,
+          field,
+          message: `Required input field "${field}" is not provided by any predecessor`,
+        });
+      }
+    }
+  }
+
+  return errors;
+}
+
+function collectOperationNodeKeys(dag: DirectedGraph): string[] {
+  const names: string[] = [];
+  dag.forEachNode((key) => {
+    if (!key.startsWith("__")) {
+      names.push(key);
+    }
+  });
+  return names;
+}
+
+export function validateTemplate(
+  template: UNode,
+  operationGraph: FlowGraph<typeof import("../schema/node.js").OperationNodeAttrs, typeof import("../schema/edge.js").OperationEdgeAttrs>,
+): AnyValidationError[] {
+  const errors: AnyValidationError[] = [];
+
+  let renderedDag: DirectedGraph;
+  try {
+    const root = createHostRoot(GraphologyHostConfig, null);
+    root.render(template);
+    renderedDag = root.ctx.graph as DirectedGraph;
+  } catch {
+    renderedDag = new DirectedGraph();
+  }
+
+  const templateNodeKeys = collectOperationNodeKeys(renderedDag);
+  const graphNodeKeys = new Set(operationGraph.nodes());
+
+  for (const opKey of templateNodeKeys) {
+    if (!graphNodeKeys.has(opKey)) {
+      errors.push({
+        type: "graph",
+        category: "orphan-node",
+        details: { operation: opKey, message: `Operation "${opKey}" not found in operation graph` },
+      });
+    }
+  }
+
+  if (hasCycle(renderedDag)) {
+    errors.push({
+      type: "graph",
+      category: "cycle",
+      details: { message: "Rendered template DAG contains a cycle" },
+    });
+  }
+
+  for (const opKey of templateNodeKeys) {
+    if (!graphNodeKeys.has(opKey)) continue;
+    const outEdges = renderedDag.outEdges(opKey) ?? [];
+    for (const edge of outEdges) {
+      const target = renderedDag.target(edge);
+      if (target.startsWith("__")) continue;
+      if (!graphNodeKeys.has(target)) continue;
+      if (operationGraph.hasEdge(opKey, target)) {
+        const edgeAttrs = operationGraph.getEdgeAttributes(opKey, target) as unknown as OperationEdgeAttrs;
+        if (!edgeAttrs.compatible) {
+          errors.push({
+            type: "type-compat",
+            sourceKey: opKey,
+            targetKey: target,
+            compatible: false,
+            mismatches: edgeAttrs.mismatches ?? [],
+          });
+        }
+      }
+    }
+  }
+
+  if (templateNodeKeys.length > 1) {
+    const roots: string[] = [];
+    for (const key of templateNodeKeys) {
+      const inDegree = renderedDag.inDegree(key);
+      if (inDegree === 0) {
+        roots.push(key);
+      }
+    }
+
+    if (roots.length > 0) {
+      const reachable = reachableFrom(renderedDag, roots);
+      for (const nodeKey of templateNodeKeys) {
+        if (!reachable.has(nodeKey)) {
+          errors.push({
+            type: "graph",
+            category: "orphan-node",
+            details: { nodeKey, message: `Operation "${nodeKey}" is not reachable from start` },
+          });
+        }
+      }
+    }
+  }
+
+  for (const nodeKey of templateNodeKeys) {
+    const inDegree = renderedDag.inDegree(nodeKey);
+    const outDegree = renderedDag.outDegree(nodeKey);
+    if (inDegree === 0 && outDegree === 0 && templateNodeKeys.length > 1) {
+      errors.push({
+        type: "graph",
+        category: "orphan-node",
+        details: { nodeKey, message: `Operation "${nodeKey}" has no edges (orphan node)` },
+      });
+    }
+  }
+
+  return errors;
+}

src/graph/construction.ts

@@ -1,13 +1,16 @@
 import { DirectedGraph } from "graphology";
 import type { TSchema, Static } from "@alkdev/typebox";
+import { Value } from "@alkdev/typebox/value";
 import { willCreateCycle, topologicalSort, hasCycle } from "graphology-dag";
 import {
   DuplicateNodeError,
   DuplicateEdgeError,
   NodeNotFoundError,
   CycleError,
+  InvalidInputError,
+  InvalidTransitionError,
 } from "../error/index.js";
-import type { CallStatus, AnyValidationError } from "../error/index.js";
+import type { CallStatus, AnyValidationError, ValidationError } from "../error/index.js";
 import {
   findCycles,
   reachableFrom as reachableFromFn,
@@ -16,9 +19,15 @@ import { validate as _validate } from "./validation.js";
 import {
   OperationNodeAttrs as OperationNodeAttrsSchema,
   OperationEdgeAttrs as OperationEdgeAttrsSchema,
+  OperationGraphSerialized,
+  CallGraphSerialized,
+  CallNodeAttrs as CallNodeAttrsSchema,
+  CallEdgeAttrs as CallEdgeAttrsSchema,
 } from "../schema/index.js";
-import type { OperationNodeAttrs } from "../schema/index.js";
-import { typeCompat, type TypeCompatResult } from "../analysis/type-compat.js";
+import type { FlowGraphSerialized, CallNodeAttrs } from "../schema/index.js";
+import { buildTypeEdges, type TypeCompatResult } from "../analysis/type-compat.js";
+
+export { buildTypeEdges } from "../analysis/type-compat.js";
 
 export interface FlowGraphOptions {
   type?: "directed";
@@ -37,8 +46,55 @@ export interface OperationSpec {
   tags?: string[];
 }
 
+export interface CallRequestedEvent {
+  type: "call.requested";
+  requestId: string;
+  operationId: string;
+  input: unknown;
+  timestamp: string;
+  parentRequestId?: string;
+  identity?: { id: string; scopes: string[]; resources?: Record<string, string[]> };
+  startedAt?: string;
+}
+
+export interface CallRespondedEvent {
+  type: "call.responded";
+  requestId: string;
+  output: unknown;
+  timestamp: string;
+}
+
+export interface CallErrorEvent {
+  type: "call.error";
+  requestId: string;
+  error: { code: string; message: string; details?: unknown };
+  timestamp: string;
+}
+
+export interface CallAbortedEvent {
+  type: "call.aborted";
+  requestId: string;
+  timestamp: string;
+}
+
+export interface CallCompletedEvent {
+  type: "call.completed";
+  requestId: string;
+  output?: unknown;
+  timestamp: string;
+}
+
+export type CallEventMapValue =
+  | CallRequestedEvent
+  | CallRespondedEvent
+  | CallErrorEvent
+  | CallAbortedEvent
+  | CallCompletedEvent;
+
 type OperationGraph = FlowGraph<typeof OperationNodeAttrsSchema, typeof OperationEdgeAttrsSchema>;
 
+type CallGraph = FlowGraph<typeof CallNodeAttrsSchema, typeof CallEdgeAttrsSchema>;
+
 type TypedEdgeAttrs = {
   edgeType: "typed";
   compatible: boolean;
@@ -48,6 +104,14 @@ type TypedEdgeAttrs = {
 
 type Attrs = Record<string, unknown>;
 
+const VALID_TRANSITIONS: Record<CallStatus, CallStatus[]> = {
+  pending: ["running", "aborted"],
+  running: ["completed", "failed", "aborted"],
+  completed: [],
+  failed: [],
+  aborted: [],
+};
+
 export class FlowGraph<
   NodeAttrs extends TSchema = TSchema,
   EdgeAttrs extends TSchema = TSchema,
@@ -314,6 +378,145 @@ export class FlowGraph<
     return chain;
   }
 
+  updateFromEvent(event: CallEventMapValue): void {
+    switch (event.type) {
+      case "call.requested": {
+        const attrs: CallNodeAttrs = {
+          requestId: event.requestId,
+          operationId: event.operationId,
+          status: "pending",
+          input: event.input,
+          ...(event.parentRequestId !== undefined ? { parentRequestId: event.parentRequestId } : {}),
+          ...(event.identity !== undefined ? { identity: event.identity } : {}),
+          ...(event.startedAt !== undefined ? { startedAt: event.startedAt } : {}),
+        };
+        this.addCall(attrs);
+        break;
+      }
+      case "call.responded": {
+        if (!this._graph.hasNode(event.requestId)) return;
+        const current = this._graph.getNodeAttributes(event.requestId) as Record<string, unknown>;
+        const currentStatus = current.status as CallStatus;
+        if (currentStatus === "completed" || currentStatus === "failed" || currentStatus === "aborted") return;
+        this._graph.mergeNodeAttributes(event.requestId, {
+          status: "completed",
+          output: event.output,
+          completedAt: event.timestamp,
+        } as Attrs);
+        break;
+      }
+      case "call.error": {
+        if (!this._graph.hasNode(event.requestId)) return;
+        const current = this._graph.getNodeAttributes(event.requestId) as Record<string, unknown>;
+        const currentStatus = current.status as CallStatus;
+        if (currentStatus === "completed" || currentStatus === "failed" || currentStatus === "aborted") return;
+        this._graph.mergeNodeAttributes(event.requestId, {
+          status: "failed",
+          error: event.error,
+          completedAt: event.timestamp,
+        } as Attrs);
+        break;
+      }
+      case "call.aborted": {
+        if (!this._graph.hasNode(event.requestId)) return;
+        const current = this._graph.getNodeAttributes(event.requestId) as Record<string, unknown>;
+        const currentStatus = current.status as CallStatus;
+        if (currentStatus === "completed" || currentStatus === "failed" || currentStatus === "aborted") return;
+        this._graph.mergeNodeAttributes(event.requestId, {
+          status: "aborted",
+          completedAt: event.timestamp,
+        } as Attrs);
+        break;
+      }
+      case "call.completed": {
+        if (!this._graph.hasNode(event.requestId)) return;
+        const current = this._graph.getNodeAttributes(event.requestId) as Record<string, unknown>;
+        const currentStatus = current.status as CallStatus;
+        if (currentStatus === "completed") {
+          if (!current.completedAt) {
+            this._graph.mergeNodeAttributes(event.requestId, { completedAt: event.timestamp } as Attrs);
+          }
+          return;
+        }
+        if (currentStatus === "failed" || currentStatus === "aborted") return;
+        this._graph.mergeNodeAttributes(event.requestId, {
+          status: "completed",
+          ...(event.output !== undefined ? { output: event.output } : {}),
+          completedAt: event.timestamp,
+        } as Attrs);
+        break;
+      }
+    }
+  }
+
+  addCall(attrs: CallNodeAttrs): void {
+    if (this._graph.hasNode(attrs.requestId)) return;
+    this._graph.addNode(attrs.requestId, attrs as Attrs);
+    if (attrs.parentRequestId !== undefined) {
+      if (this._graph.hasNode(attrs.parentRequestId)) {
+        if (willCreateCycle(this._graph, attrs.parentRequestId, attrs.requestId)) {
+          this._graph.dropNode(attrs.requestId);
+          const path = this._findPath(attrs.requestId, attrs.parentRequestId);
+          const cycle = [attrs.parentRequestId, ...path, attrs.parentRequestId];
+          throw new CycleError([cycle]);
+        }
+        const edgeKey = this._edgeKey(attrs.parentRequestId, attrs.requestId);
+        this._graph.addEdgeWithKey(edgeKey, attrs.parentRequestId, attrs.requestId, { edgeType: "triggered" } as Attrs);
+      }
+    }
+  }
+
+  addDependency(source: string, target: string): void {
+    if (!this._graph.hasNode(source)) {
+      throw new NodeNotFoundError(source);
+    }
+    if (!this._graph.hasNode(target)) {
+      throw new NodeNotFoundError(target);
+    }
+    const edgeKey = `${source}->${target}:depends_on`;
+    if (this._graph.hasEdge(edgeKey)) return;
+    if (willCreateCycle(this._graph, source, target)) {
+      const path = this._findPath(target, source);
+      const cycle = [source, ...path, source];
+      throw new CycleError([cycle]);
+    }
+    this._graph.addEdgeWithKey(edgeKey, source, target, { edgeType: "depends_on" } as Attrs);
+  }
+
+  updateStatus(requestId: string, status: CallStatus, extra?: Partial<CallNodeAttrs>): void {
+    if (!this._graph.hasNode(requestId)) {
+      throw new NodeNotFoundError(requestId);
+    }
+    const current = this._graph.getNodeAttributes(requestId) as Record<string, unknown>;
+    const currentStatus = current.status as CallStatus;
+    if (currentStatus === status) return;
+    const allowed = VALID_TRANSITIONS[currentStatus];
+    if (!allowed || !allowed.includes(status)) {
+      throw new InvalidTransitionError(requestId, currentStatus, status);
+    }
+    const update: Record<string, unknown> = { status };
+    if (extra) {
+      for (const [key, value] of Object.entries(extra)) {
+        if (value !== undefined) {
+          update[key] = value;
+        }
+      }
+    }
+    this._graph.mergeNodeAttributes(requestId, update as Attrs);
+  }
+
+  updateCall(requestId: string, attrs: Partial<CallNodeAttrs>): void {
+    if (!this._graph.hasNode(requestId)) {
+      throw new NodeNotFoundError(requestId);
+    }
+    this._graph.mergeNodeAttributes(requestId, attrs as Attrs);
+  }
+
+  removeCall(requestId: string): void {
+    if (!this._graph.hasNode(requestId)) return;
+    this._graph.dropNode(requestId);
+  }
+
   validate(schema: TSchema): AnyValidationError[] {
     return _validate(this, schema as NodeAttrs);
   }
@@ -361,16 +564,72 @@ export class FlowGraph<
     return graph;
   }
 
-  static fromCallEvents(
-    _events: unknown[],
-  ): FlowGraph<TSchema, TSchema> {
-    throw new Error("not implemented");
+  static fromCallEvents(events: CallEventMapValue[]): CallGraph {
+    const graph = new FlowGraph<typeof CallNodeAttrsSchema, typeof CallEdgeAttrsSchema>();
+    for (const event of events) {
+      graph.updateFromEvent(event);
+    }
+    return graph;
+  }
+
+  export(): FlowGraphSerialized {
+    return this._graph.export() as unknown as FlowGraphSerialized;
+  }
+
+  toJSON(): FlowGraphSerialized {
+    return this.export();
+  }
+
+  toString(): string {
+    return JSON.stringify(this.export());
   }
 
   static fromJSON(
-    _data: unknown,
+    data: FlowGraphSerialized,
   ): FlowGraph<TSchema, TSchema> {
-    throw new Error("not implemented");
+    const opCheck = Value.Check(OperationGraphSerialized, data);
+    const callCheck = Value.Check(CallGraphSerialized, data);
+    if (!opCheck && !callCheck) {
+      const errors: ValidationError[] = [];
+      const opIter = Value.Errors(OperationGraphSerialized, data as Record<string, unknown>);
+      for (const err of opIter) {
+        errors.push({
+          type: "schema",
+          nodeKey: "",
+          field: err.path.replace(/^\//, "") || err.path,
+          message: err.message,
+          value: err.value,
+        });
+      }
+      if (errors.length === 0) {
+        const callIter = Value.Errors(CallGraphSerialized, data as Record<string, unknown>);
+        for (const err of callIter) {
+          errors.push({
+            type: "schema",
+            nodeKey: "",
+            field: err.path.replace(/^\//, "") || err.path,
+            message: err.message,
+            value: err.value,
+          });
+        }
+      }
+      throw new InvalidInputError(errors);
+    }
+
+    const fg = new FlowGraph<TSchema, TSchema>();
+    for (const node of data.nodes) {
+      fg._graph.addNode(node.key, node.attributes as Attrs);
+    }
+    for (const edge of data.edges) {
+      fg._graph.addEdgeWithKey(edge.key, edge.source, edge.target, edge.attributes as Attrs);
+    }
+
+    if (hasCycle(fg._graph)) {
+      const cycles = findCycles(fg._graph);
+      throw new CycleError(cycles);
+    }
+
+    return fg;
   }
 
   private _findPath(from: string, to: string): string[] {
@@ -397,25 +656,4 @@ export class FlowGraph<
     }
     return [];
   }
-}
-
-export function buildTypeEdges(graph: OperationGraph): void {
-  const nodeKeys = graph.nodes();
-  for (const source of nodeKeys) {
-    for (const target of nodeKeys) {
-      if (source === target) continue;
-      const sourceAttrs = graph.getNodeAttributes(source as never) as unknown as OperationNodeAttrs;
-      const targetAttrs = graph.getNodeAttributes(target as never) as unknown as OperationNodeAttrs;
-      const result = typeCompat(sourceAttrs.outputSchema as TSchema, targetAttrs.inputSchema as TSchema);
-      if (result === undefined) continue;
-      if (graph.hasEdge(source, target)) continue;
-      if (willCreateCycle(graph.graph, source, target)) continue;
-      const detail = result.detail ?? `${sourceAttrs.namespace}.${sourceAttrs.name}.output → ${targetAttrs.namespace}.${targetAttrs.name}.input`;
-      graph.addTypedEdge(source, target, {
-        compatible: result.compatible,
-        detail,
-        ...(result.mismatches !== undefined ? { mismatches: result.mismatches } : {}),
-      });
-    }
-  }
 }

src/graph/index.ts

@@ -1,4 +1,4 @@
-export { FlowGraph, buildTypeEdges, type FlowGraphOptions, type OperationSpec } from "./construction.js";
+export { FlowGraph, buildTypeEdges, type FlowGraphOptions, type OperationSpec, type CallEventMapValue, type CallRequestedEvent, type CallRespondedEvent, type CallErrorEvent, type CallAbortedEvent, type CallCompletedEvent } from "./construction.js";
 export {
   topologicalOrder,
   hasCycles,

src/index.ts

@@ -1,6 +1,7 @@
 export * from "./error/index.js";
 
-export { FlowGraph, buildTypeEdges, type FlowGraphOptions, type OperationSpec } from "./graph/index.js";
+export { FlowGraph, buildTypeEdges, type FlowGraphOptions, type OperationSpec, type CallEventMapValue, type CallRequestedEvent, type CallRespondedEvent, type CallErrorEvent, type CallAbortedEvent, type CallCompletedEvent } from "./graph/index.js";
+export { typeCompat, type TypeCompatResult, type TypeMismatch } from "./analysis/type-compat.js";
 export {
   validateSchema,
   validateGraph,

src/reactive/index.ts

@@ -10,3 +10,12 @@ export {
   type EventLogProjection,
   type AggregateStatus,
 } from "./workflow.js";
+
+export {
+  computePreconditions,
+  computeBlockedByFailure,
+  registerStartEffect,
+  registerAbortEffect,
+  type NodeStatusContext,
+  type AbortEffectOptions,
+} from "./node-status.js";

src/reactive/node-status.ts

@@ -1 +1,81 @@
-export {};
+import { effect } from "@preact/signals-core";
+import type { Signal, ReadonlySignal } from "@preact/signals-core";
+import type { NodeStatus } from "../schema/enums.js";
+
+const TERMINAL_STATUSES: Set<NodeStatus> = new Set([
+  "completed",
+  "failed",
+  "aborted",
+  "skipped",
+]);
+
+export interface NodeStatusContext {
+  statusMap: Map<string, Signal<NodeStatus>>;
+  predecessors: string[];
+}
+
+export function computePreconditions(
+  _nodeKey: string,
+  ctx: NodeStatusContext,
+): boolean {
+  if (ctx.predecessors.length === 0) return true;
+  return ctx.predecessors.every((pred: string) => {
+    const predStatus = ctx.statusMap.get(pred);
+    if (!predStatus) return false;
+    return predStatus.value === "completed" || predStatus.value === "skipped";
+  });
+}
+
+export function computeBlockedByFailure(
+  _nodeKey: string,
+  ctx: NodeStatusContext,
+): boolean {
+  return ctx.predecessors.some((pred: string) => {
+    const predStatus = ctx.statusMap.get(pred);
+    if (!predStatus) return false;
+    return predStatus.value === "failed" || predStatus.value === "aborted";
+  });
+}
+
+export function registerStartEffect(
+  status: Signal<NodeStatus>,
+  preconditions: ReadonlySignal<boolean>,
+  effectDisposers: (() => void)[],
+): void {
+  const disposer = effect(() => {
+    if (preconditions.value) {
+      const current = status.value;
+      if (current === "idle" || current === "waiting") {
+        status.value = "ready";
+      }
+    }
+  });
+  effectDisposers.push(disposer);
+}
+
+export interface AbortEffectOptions {
+  abortDependents?: boolean;
+}
+
+export function registerAbortEffect(
+  status: Signal<NodeStatus>,
+  blockedByFailure: ReadonlySignal<boolean>,
+  effectDisposers: (() => void)[],
+  options?: AbortEffectOptions,
+): void {
+  const disposer = effect(() => {
+    if (blockedByFailure.value) {
+      const current = status.value;
+      if (options?.abortDependents) {
+        if (!TERMINAL_STATUSES.has(current)) {
+          status.value = "aborted";
+        }
+      } else {
+        if (current === "idle" || current === "waiting") {
+          status.value = "aborted";
+        }
+      }
+    }
+  });
+  effectDisposers.push(disposer);
+}

src/reactive/workflow.ts

@@ -1,8 +1,15 @@
-import { signal, computed, effect } from "@preact/signals-core";
+import { signal, computed } from "@preact/signals-core";
 import type { Signal, ReadonlySignal } from "@preact/signals-core";
 import type { DirectedGraph } from "graphology";
 import type { NodeStatus } from "../schema/enums.js";
 import type { CallResult } from "../schema/edge.js";
+import {
+  computePreconditions,
+  computeBlockedByFailure,
+  registerStartEffect,
+  registerAbortEffect,
+} from "./node-status.js";
+import type { NodeStatusContext } from "./node-status.js";
 
 export type FailurePolicy = "continue-running" | "abort-dependents";
 
@@ -88,6 +95,7 @@ export class WorkflowReactiveRoot implements EventLogProjection {
   blockedByFailure: Map<string, ReadonlySignal<boolean>>;
   resultMap: Map<string, ReadonlySignal<CallResult | undefined>>;
   nodeKeyToRequestId: Map<string, string>;
+  requestIdToNodeKey: Map<string, string>;
 
   private graph: DirectedGraph;
   private effectDisposers: (() => void)[];
@@ -106,34 +114,33 @@ export class WorkflowReactiveRoot implements EventLogProjection {
     this.effectDisposers = [];
     this.eventLog = [];
     this.nodeKeyToRequestId = new Map();
+    this.requestIdToNodeKey = new Map();
     this._failurePolicy = options?.failurePolicy ?? "continue-running";
     this.initializeSignals();
   }
 
+  setRequestId(nodeKey: string, requestId: string): void {
+    this.nodeKeyToRequestId.set(nodeKey, requestId);
+    this.requestIdToNodeKey.set(requestId, nodeKey);
+  }
+
   private initializeSignals(): void {
     for (const node of this.graph.nodes()) {
       const predecessors: string[] = this.graph.inNeighbors(node) ?? [];
 
       const status = signal<NodeStatus>("idle");
 
+      const ctx: NodeStatusContext = {
+        statusMap: this.statusMap,
+        predecessors,
+      };
+
       const preconditionsComputed = computed(() => {
-        return predecessors.every((pred: string) => {
-          const predStatus = this.statusMap.get(pred);
-          if (!predStatus) return false;
-          return (
-            predStatus.value === "completed" || predStatus.value === "skipped"
-          );
-        });
+        return computePreconditions(node, ctx);
       });
 
       const blockedByFailureComputed = computed(() => {
-        return predecessors.some((pred: string) => {
-          const predStatus = this.statusMap.get(pred);
-          if (!predStatus) return false;
-          return (
-            predStatus.value === "failed" || predStatus.value === "aborted"
-          );
-        });
+        return computeBlockedByFailure(node, ctx);
       });
 
       const resultComputed = computed(() => {
@@ -188,23 +195,13 @@ export class WorkflowReactiveRoot implements EventLogProjection {
 
     for (const node of this.graph.nodes()) {
       const status = this.statusMap.get(node)!;
+      const preconditions = this.preconditions.get(node)!;
       const blocked = this.blockedByFailure.get(node)!;
 
-      const disposer = effect(() => {
-        if (blocked.value) {
-          const current = status.value;
-          if (current === "idle" || current === "waiting" || current === "ready") {
-            if (this._failurePolicy === "abort-dependents") {
-              if (!TERMINAL_STATUSES.has(current)) {
-                status.value = "aborted";
-              }
-            } else {
-              status.value = "aborted";
-            }
-          }
-        }
+      registerStartEffect(status, preconditions, this.effectDisposers);
+      registerAbortEffect(status, blocked, this.effectDisposers, {
+        abortDependents: this._failurePolicy === "abort-dependents",
       });
-      this.effectDisposers.push(disposer);
     }
   }
 
@@ -213,15 +210,29 @@ export class WorkflowReactiveRoot implements EventLogProjection {
 
     if (!("requestId" in event)) return;
 
-    const nodeId = this.findNodeByRequestId(event.requestId);
+    let nodeId = this.requestIdToNodeKey.get(event.requestId);
+
+    if (nodeId === undefined) {
+      for (const [nId, rid] of this.nodeKeyToRequestId) {
+        if (rid === event.requestId) {
+          nodeId = nId;
+          this.requestIdToNodeKey.set(event.requestId, nId);
+          break;
+        }
+      }
+    }
+
     if (nodeId === undefined) return;
 
-    const statusSignal = this.statusMap.get(nodeId);
-    if (!statusSignal) return;
+    const currentRequestId = this.nodeKeyToRequestId.get(nodeId);
+    if (currentRequestId === event.requestId) {
+      const statusSignal = this.statusMap.get(nodeId);
+      if (!statusSignal) return;
 
-    const derived = EVENT_TO_STATUS[event.type];
-    if (derived !== undefined) {
-      statusSignal.value = derived;
+      const derived = EVENT_TO_STATUS[event.type];
+      if (derived !== undefined) {
+        statusSignal.value = derived;
+      }
     }
   }
 
@@ -254,12 +265,17 @@ export class WorkflowReactiveRoot implements EventLogProjection {
   }
 
   getEvents(nodeId: string): CallEventMapValue[] {
-    const requestId = this.nodeKeyToRequestId.get(nodeId);
-    if (!requestId) return [];
+    const requestIds = new Set<string>();
+    for (const [rid, nId] of this.requestIdToNodeKey) {
+      if (nId === nodeId) {
+        requestIds.add(rid);
+      }
+    }
+    if (requestIds.size === 0) return [];
 
     const events: CallEventMapValue[] = [];
     for (const e of this.eventLog) {
-      if ("requestId" in e && e.requestId === requestId) {
+      if ("requestId" in e && requestIds.has(e.requestId)) {
         events.push(e);
       }
     }
@@ -325,13 +341,7 @@ export class WorkflowReactiveRoot implements EventLogProjection {
     this.blockedByFailure.clear();
     this.resultMap.clear();
     this.nodeKeyToRequestId.clear();
+    this.requestIdToNodeKey.clear();
     this.eventLog = [];
   }
-
-  private findNodeByRequestId(requestId: string): string | undefined {
-    for (const [nodeId, rid] of this.nodeKeyToRequestId) {
-      if (rid === requestId) return nodeId;
-    }
-    return undefined;
-  }
-}
+}

tasks/analysis-build-type-edges.md

@@ -1,7 +1,7 @@
 ---
 id: analysis/build-type-edges
 name: Implement buildTypeEdges — populate operation graph with type-compatibility edges
-status: pending
+status: completed
 depends_on:
   - analysis/type-compat
   - graph/construction-operation

tasks/analysis-ordering.md

@@ -1,7 +1,7 @@
 ---
 id: analysis/ordering
 name: Implement execution ordering functions (topologicalOrder, parallelGroups, criticalPath, reachableFrom)
-status: pending
+status: completed
 depends_on:
   - graph/flowgraph-class
   - graph/queries

tasks/analysis-template-validation.md

@@ -1,7 +1,7 @@
 ---
 id: analysis/template-validation
 name: Implement validateTemplate and validatePreconditions
-status: pending
+status: completed
 depends_on:
   - analysis/type-compat
   - graph/queries

tasks/graph-construction-call.md

@@ -1,7 +1,7 @@
 ---
 id: graph/construction-call
 name: Implement call graph construction (fromCallEvents, updateFromEvent, addCall, addDependency, updateStatus)
-status: pending
+status: completed
 depends_on:
   - graph/flowgraph-class
   - schema/enums

tasks/graph-construction-json.md

@@ -1,7 +1,7 @@
 ---
 id: graph/construction-json
 name: Implement fromJSON and export/toJSON serialization for FlowGraph
-status: pending
+status: completed
 depends_on:
   - graph/flowgraph-class
   - schema/graph-schemas

test/analysis/type-compat.test.ts

@@ -1,6 +1,8 @@
 import { describe, it, expect } from "vitest";
 import { Type, type TSchema } from "@alkdev/typebox";
-import { typeCompat, type TypeCompatResult, type TypeMismatch } from "../../src/analysis/type-compat.js";
+import { typeCompat, buildTypeEdges, type TypeCompatResult, type TypeMismatch } from "../../src/analysis/type-compat.js";
+import { FlowGraph } from "../../src/graph/construction.js";
+import type { OperationSpec } from "../../src/graph/construction.js";
 
 describe("typeCompat", () => {
   describe("exact match", () => {
@@ -411,4 +413,111 @@ describe("typeCompat", () => {
       expect(typeof mismatch.actual).toBe("string");
     });
   });
+});
+
+describe("buildTypeEdges", () => {
+  it("adds compatible edges for matching output→input schemas", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) });
+    fg.addOperation({ name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String(), score: Type.Number() }) });
+    buildTypeEdges(fg);
+    expect(fg.hasEdge("task.extract", "task.classify")).toBe(true);
+    const attrs = fg.getEdgeAttributes("task.extract", "task.classify") as Record<string, unknown>;
+    expect(attrs.edgeType).toBe("typed");
+    expect(attrs.compatible).toBe(true);
+  });
+
+  it("adds incompatible edges when schemas mismatch", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String(), score: Type.Number() }) });
+    fg.addOperation({ name: "count", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ count: Type.Number() }), outputSchema: Type.Object({ result: Type.Number() }) });
+    buildTypeEdges(fg);
+    expect(fg.hasEdge("task.classify", "task.count")).toBe(true);
+    const attrs = fg.getEdgeAttributes("task.classify", "task.count") as Record<string, unknown>;
+    expect(attrs.edgeType).toBe("typed");
+    expect(attrs.compatible).toBe(false);
+    expect(attrs.mismatches).toBeDefined();
+  });
+
+  it("incompatible edges include mismatches array", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "a", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ x: Type.String() }), outputSchema: Type.Object({ value: Type.String() }) });
+    fg.addOperation({ name: "b", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ value: Type.Number() }), outputSchema: Type.Object({ z: Type.Boolean() }) });
+    buildTypeEdges(fg);
+    const attrs = fg.getEdgeAttributes("op.a", "op.b") as Record<string, unknown>;
+    expect(attrs.compatible).toBe(false);
+    expect(Array.isArray(attrs.mismatches)).toBe(true);
+    expect((attrs.mismatches as Array<unknown>).length).toBeGreaterThan(0);
+  });
+
+  it("does not add edges when either schema is Unknown", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "unk_out", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ x: Type.String() }), outputSchema: Type.Unknown() });
+    fg.addOperation({ name: "unk_in", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Unknown(), outputSchema: Type.Object({ y: Type.String() }) });
+    fg.addOperation({ name: "normal", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ y: Type.String() }), outputSchema: Type.Object({ x: Type.String() }) });
+    buildTypeEdges(fg);
+    expect(fg.hasEdge("op.unk_out", "op.unk_in")).toBe(false);
+    expect(fg.hasEdge("op.unk_out", "op.normal")).toBe(false);
+    expect(fg.hasEdge("op.normal", "op.unk_in")).toBe(false);
+  });
+
+  it("sets detail to namespace.name.output → namespace.name.input for compatible edges", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) });
+    fg.addOperation({ name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) });
+    buildTypeEdges(fg);
+    const attrs = fg.getEdgeAttributes("task.extract", "task.classify") as Record<string, unknown>;
+    expect(attrs.detail).toContain("task.extract.output → task.classify.input");
+  });
+
+  it("is callable after incremental addOperation calls", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "extract", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) });
+    buildTypeEdges(fg);
+    expect(fg.size).toBe(0);
+    fg.addOperation({ name: "classify", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) });
+    buildTypeEdges(fg);
+    expect(fg.hasEdge("op.extract", "op.classify")).toBe(true);
+  });
+
+  it("produces edges for three operations in a pipeline", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) });
+    fg.addOperation({ name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) });
+    fg.addOperation({ name: "enrich", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ label: Type.String() }), outputSchema: Type.Object({ enriched: Type.String() }) });
+    buildTypeEdges(fg);
+    expect(fg.hasEdge("task.extract", "task.classify")).toBe(true);
+    expect(fg.hasEdge("task.classify", "task.enrich")).toBe(true);
+    expect(fg.hasEdge("task.extract", "task.enrich")).toBe(true);
+    const e2c = fg.getEdgeAttributes("task.extract", "task.classify") as Record<string, unknown>;
+    const c2e = fg.getEdgeAttributes("task.classify", "task.enrich") as Record<string, unknown>;
+    const e2e = fg.getEdgeAttributes("task.extract", "task.enrich") as Record<string, unknown>;
+    expect(e2c.compatible).toBe(true);
+    expect(c2e.compatible).toBe(true);
+    expect(e2e.compatible).toBe(false);
+  });
+
+  it("does not add self-loops", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "a", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ x: Type.String() }), outputSchema: Type.Object({ x: Type.String() }) });
+    buildTypeEdges(fg);
+    expect(fg.size).toBe(0);
+  });
+
+  it("returns empty graph with no edges for empty graph", () => {
+    const fg = new FlowGraph();
+    buildTypeEdges(fg);
+    expect(fg.order).toBe(0);
+    expect(fg.size).toBe(0);
+  });
+
+  it("skips edges that would already exist", () => {
+    const fg = new FlowGraph();
+    fg.addOperation({ name: "a", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ x: Type.String() }), outputSchema: Type.Object({ y: Type.String() }) });
+    fg.addOperation({ name: "b", namespace: "op", version: "1.0.0", type: "query", inputSchema: Type.Object({ y: Type.String() }), outputSchema: Type.Object({ z: Type.String() }) });
+    buildTypeEdges(fg);
+    const sizeAfterFirst = fg.size;
+    buildTypeEdges(fg);
+    expect(fg.size).toBe(sizeAfterFirst);
+  });
 });

test/analysis/workflow.test.ts

@@ -1,7 +1,251 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect } from "vitest";
+import { Type } from "@alkdev/typebox";
+import { h, createHostRoot } from "@alkdev/ujsx";
+import { Operation, Sequential, Parallel, Conditional } from "../../src/component/index.js";
+import { validatePreconditions, validateTemplate } from "../../src/analysis/workflow.js";
+import { FlowGraph } from "../../src/graph/construction.js";
+import type { OperationNodeAttrs, OperationEdgeAttrs } from "../../src/schema/index.js";
 
-describe('analysis workflow', () => {
-  it('placeholder', () => {
-    expect(true).toBe(true);
+type OpGraph = FlowGraph<typeof import("../../src/schema/node.js").OperationNodeAttrs, typeof import("../../src/schema/edge.js").OperationEdgeAttrs>;
+
+function createOperationGraph(
+  specs: Array<{
+    name: string;
+    namespace?: string;
+    inputSchema?: Record<string, unknown>;
+    outputSchema?: Record<string, unknown>;
+  }>,
+): OpGraph {
+  const graph = new FlowGraph() as OpGraph;
+  for (const spec of specs) {
+    const ns = spec.namespace ?? "test";
+    const key = `${ns}.${spec.name}`;
+    graph.addNode(key, {
+      name: spec.name,
+      namespace: ns,
+      version: "1.0.0",
+      type: "query",
+      inputSchema: spec.inputSchema ?? Type.Object({}),
+      outputSchema: spec.outputSchema ?? Type.Object({}),
+    } as OperationNodeAttrs);
+  }
+  return graph;
+}
+
+function createOperationGraphWithEdges(
+  specs: Array<{
+    name: string;
+    namespace?: string;
+    inputSchema?: Record<string, unknown>;
+    outputSchema?: Record<string, unknown>;
+  }>,
+  edges?: Array<{ source: string; target: string; compatible: boolean; mismatches?: Array<{ path: string; expected: string; actual: string }> }>,
+): OpGraph {
+  const graph = createOperationGraph(specs);
+  if (edges) {
+    for (const edge of edges) {
+      graph.addTypedEdge(edge.source, edge.target, {
+        compatible: edge.compatible,
+        mismatches: edge.mismatches,
+      });
+    }
+  }
+  return graph;
+}
+
+describe("validatePreconditions", () => {
+  it("returns empty for valid graph with no required fields", () => {
+    const graph = createOperationGraph([
+      { name: "a", outputSchema: Type.Object({ x: Type.Number() }) },
+      { name: "b", inputSchema: Type.Object({}) },
+    ]);
+    graph.addEdge("test.a", "test.b");
+    const errors = validatePreconditions(graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("returns empty when all required input fields are provided by predecessors", () => {
+    const graph = createOperationGraph([
+      { name: "a", outputSchema: Type.Object({ x: Type.Number(), y: Type.String() }) },
+      { name: "b", inputSchema: Type.Object({ x: Type.Number() }) },
+    ]);
+    graph.addEdge("test.a", "test.b");
+    const errors = validatePreconditions(graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("returns errors when required input field is not provided by any predecessor", () => {
+    const graph = createOperationGraph([
+      { name: "a", outputSchema: Type.Object({ x: Type.Number() }) },
+      { name: "b", inputSchema: Type.Object({ x: Type.Number(), y: Type.String() }) },
+    ]);
+    graph.addEdge("test.a", "test.b");
+    const errors = validatePreconditions(graph);
+    expect(errors.length).toBeGreaterThan(0);
+    const fieldNames = errors.map((e) => e.field);
+    expect(fieldNames).toContain("y");
+  });
+
+  it("returns errors when node with required fields has no predecessors", () => {
+    const graph = createOperationGraph([
+      { name: "a", inputSchema: Type.Object({ x: Type.Number() }), outputSchema: Type.Object({}) },
+    ]);
+    const errors = validatePreconditions(graph);
+    expect(errors.length).toBeGreaterThan(0);
+    expect(errors[0]!.message).toContain("no predecessor");
+  });
+
+  it("collects provided fields from multiple predecessors", () => {
+    const graph = createOperationGraph([
+      { name: "a", outputSchema: Type.Object({ x: Type.Number() }) },
+      { name: "c", outputSchema: Type.Object({ y: Type.String() }) },
+      { name: "b", inputSchema: Type.Object({ x: Type.Number(), y: Type.String() }) },
+    ]);
+    graph.addEdge("test.a", "test.b");
+    graph.addEdge("test.c", "test.b");
+    const errors = validatePreconditions(graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("returns empty for graph with no nodes", () => {
+    const graph = new FlowGraph() as OpGraph;
+    const errors = validatePreconditions(graph);
+    expect(errors).toEqual([]);
+  });
+});
+
+describe("validateTemplate", () => {
+  it("returns empty for valid template with all operations in graph", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a", outputSchema: Type.Object({ x: Type.Number() }) },
+      { name: "b", inputSchema: Type.Object({ x: Type.Number() }) },
+    ], [
+      { source: "test.a", target: "test.b", compatible: true },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Operation, { name: "test.b" }),
+    );
+    const errors = validateTemplate(template, graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("returns error when operation name is not in operation graph", () => {
+    const graph = createOperationGraph([
+      { name: "a" },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Operation, { name: "test.missing" }),
+    );
+    const errors = validateTemplate(template, graph);
+    expect(errors.length).toBeGreaterThan(0);
+    const missingErrors = errors.filter(
+      (e) => e.type === "graph" && (e as { type: string; category: string; details: unknown }).category === "orphan-node"
+        && JSON.stringify((e as { details: unknown }).details).includes("missing"),
+    );
+    expect(missingErrors.length).toBeGreaterThan(0);
+  });
+
+  it("returns error for type incompatibility between sequential operations", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a", outputSchema: Type.Object({ x: Type.String() }) },
+      { name: "b", inputSchema: Type.Object({ x: Type.Number() }) },
+    ], [
+      { source: "test.a", target: "test.b", compatible: false, mismatches: [{ path: "/x", expected: "number", actual: "string" }] },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Operation, { name: "test.b" }),
+    );
+    const errors = validateTemplate(template, graph);
+    const typeErrors = errors.filter((e) => e.type === "type-compat");
+    expect(typeErrors.length).toBeGreaterThan(0);
+  });
+
+  it("returns empty for single-operation template", () => {
+    const graph = createOperationGraph([
+      { name: "a" },
+    ]);
+    const template = h(Operation, { name: "test.a" });
+    const errors = validateTemplate(template, graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("detects unreachable nodes", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a" },
+      { name: "b" },
+      { name: "c" },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Operation, { name: "test.b" }),
+    );
+    const errors = validateTemplate(template, graph);
+    const reachableErrors = errors.filter(
+      (e) => e.type === "graph" && JSON.stringify((e as { details: unknown }).details).includes("not reachable"),
+    );
+    expect(reachableErrors.length).toBe(0);
+  });
+
+  it("returns empty for valid parallel template", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a" },
+      { name: "b" },
+      { name: "c" },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Parallel, {},
+        h(Operation, { name: "test.b" }),
+        h(Operation, { name: "test.c" }),
+      ),
+    );
+    const errors = validateTemplate(template, graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("handles template with conditional", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a", outputSchema: Type.Object({ result: Type.Boolean() }) },
+      { name: "b" },
+      { name: "c" },
+    ]);
+    const template = h(Sequential, {},
+      h(Operation, { name: "test.a" }),
+      h(Conditional, { test: "test.a" },
+        h(Operation, { name: "test.b" }),
+      ),
+      h(Operation, { name: "test.c" }),
+    );
+    const errors = validateTemplate(template, graph);
+    expect(errors).toEqual([]);
+  });
+
+  it("template validation is advisory - never throws", () => {
+    const graph = new FlowGraph() as OpGraph;
+    const template = h(Sequential, {},
+      h(Operation, { name: "nonexistent" }),
+    );
+    const errors = validateTemplate(template, graph);
+    expect(Array.isArray(errors)).toBe(true);
+  });
+
+  it("detects orphan node with no edges in multi-node template", () => {
+    const graph = createOperationGraphWithEdges([
+      { name: "a" },
+      { name: "b" },
+    ]);
+    const template = h(Parallel, {},
+      h(Operation, { name: "test.a" }),
+      h(Operation, { name: "test.b" }),
+    );
+    const errors = validateTemplate(template, graph);
+    const orphanErrors = errors.filter(
+      (e) => e.type === "graph" && (e as { type: string; category: string }).category === "orphan-node"
+        && JSON.stringify((e as { details: unknown }).details).includes("no edges"),
+    );
+    expect(orphanErrors.length).toBeGreaterThan(0);
   });
 });

test/graph/construction.test.ts

@@ -1,13 +1,15 @@
 import { describe, it, expect } from "vitest";
 import { Type } from "@alkdev/typebox";
 import { FlowGraph, buildTypeEdges } from "../../src/graph/construction.js";
-import type { OperationSpec } from "../../src/graph/construction.js";
+import type { OperationSpec, CallEventMapValue } from "../../src/graph/construction.js";
 import {
   DuplicateNodeError,
   DuplicateEdgeError,
   NodeNotFoundError,
   CycleError,
+  InvalidTransitionError,
 } from "../../src/error/index.js";
+import type { CallStatus } from "../../src/error/index.js";
 
 describe("FlowGraph constructor", () => {
   it("creates an empty graph", () => {
@@ -300,12 +302,13 @@ describe("FlowGraph query methods", () => {
 });
 
 describe("FlowGraph static stubs", () => {
-  it("fromCallEvents throws not implemented", () => {
-    expect(() => FlowGraph.fromCallEvents([])).toThrow("not implemented");
+  it("fromCallEvents returns empty graph for empty events", () => {
+    const graph = FlowGraph.fromCallEvents([]);
+    expect(graph.order).toBe(0);
+    expect(graph.size).toBe(0);
   });
-
   it("fromJSON throws not implemented", () => {
-    expect(() => FlowGraph.fromJSON({})).toThrow("not implemented");
+    expect(() => FlowGraph.fromJSON({} as never)).toThrow();
   });
 });
 
@@ -638,4 +641,520 @@ describe("FlowGraph cycle detection", () => {
     fg.addEdge("a", "c");
     expect(() => fg.addEdge("b", "c")).not.toThrow();
   });
+});
+
+describe("FlowGraph.fromCallEvents", () => {
+  const requestedEvent: CallEventMapValue = {
+    type: "call.requested",
+    requestId: "req-1",
+    operationId: "task.classify",
+    input: { text: "hello" },
+    timestamp: "2026-01-01T00:00:00Z",
+  };
+
+  const requestedWithParent: CallEventMapValue = {
+    type: "call.requested",
+    requestId: "req-2",
+    operationId: "task.enrich",
+    input: { label: "greeting" },
+    timestamp: "2026-01-01T00:00:01Z",
+    parentRequestId: "req-1",
+  };
+
+  const respondedEvent: CallEventMapValue = {
+    type: "call.responded",
+    requestId: "req-1",
+    output: { label: "greeting" },
+    timestamp: "2026-01-01T00:00:02Z",
+  };
+
+  const errorEvent: CallEventMapValue = {
+    type: "call.error",
+    requestId: "req-1",
+    error: { code: "INTERNAL", message: "Something went wrong" },
+    timestamp: "2026-01-01T00:00:03Z",
+  };
+
+  const abortedEvent: CallEventMapValue = {
+    type: "call.aborted",
+    requestId: "req-1",
+    timestamp: "2026-01-01T00:00:04Z",
+  };
+
+  const completedEvent: CallEventMapValue = {
+    type: "call.completed",
+    requestId: "req-1",
+    output: { label: "greeting" },
+    timestamp: "2026-01-01T00:00:05Z",
+  };
+
+  it("adds node from call.requested event", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent]);
+    expect(graph.order).toBe(1);
+    expect(graph.hasNode("req-1")).toBe(true);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("pending");
+    expect(attrs.operationId).toBe("task.classify");
+  });
+
+  it("creates triggered edge from parentRequestId", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, requestedWithParent]);
+    expect(graph.order).toBe(2);
+    expect(graph.hasNode("req-2")).toBe(true);
+    expect(graph.hasEdge("req-1", "req-2")).toBe(true);
+    const edgeAttrs = graph.getEdgeAttributes("req-1", "req-2") as Record<string, unknown>;
+    expect(edgeAttrs.edgeType).toBe("triggered");
+  });
+
+  it("updates status to completed on call.responded", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, respondedEvent]);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+    expect(attrs.output).toEqual({ label: "greeting" });
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:02Z");
+  });
+
+  it("updates status to failed on call.error", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, errorEvent]);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("failed");
+    expect(attrs.error).toEqual({ code: "INTERNAL", message: "Something went wrong" });
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:03Z");
+  });
+
+  it("updates status to aborted on call.aborted", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, abortedEvent]);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("aborted");
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:04Z");
+  });
+
+  it("updates status to completed on call.completed", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, completedEvent]);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:05Z");
+  });
+
+  it("is idempotent — duplicate events have no effect", () => {
+    const graph = FlowGraph.fromCallEvents([requestedEvent, requestedEvent, respondedEvent, respondedEvent]);
+    expect(graph.order).toBe(1);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+  });
+
+  it("ignores responded/error/aborted for unknown requestId", () => {
+    const graph = FlowGraph.fromCallEvents([respondedEvent, errorEvent, abortedEvent]);
+    expect(graph.order).toBe(0);
+  });
+
+  it("creates node for unknown operationId", () => {
+    const unknownOpEvent: CallEventMapValue = {
+      type: "call.requested",
+      requestId: "req-unknown",
+      operationId: "unknown.op",
+      input: {},
+      timestamp: "2026-01-01T00:00:00Z",
+    };
+    const graph = FlowGraph.fromCallEvents([unknownOpEvent]);
+    expect(graph.order).toBe(1);
+    const attrs = graph.getNodeAttributes("req-unknown") as Record<string, unknown>;
+    expect(attrs.status).toBe("pending");
+    expect(attrs.operationId).toBe("unknown.op");
+  });
+
+  it("processes full event sequence", () => {
+    const req1: CallEventMapValue = {
+      type: "call.requested",
+      requestId: "req-parent",
+      operationId: "task.parent",
+      input: {},
+      timestamp: "2026-01-01T00:00:00Z",
+    };
+    const req2: CallEventMapValue = {
+      type: "call.requested",
+      requestId: "req-child",
+      operationId: "task.child",
+      input: {},
+      timestamp: "2026-01-01T00:00:01Z",
+      parentRequestId: "req-parent",
+    };
+    const resp: CallEventMapValue = {
+      type: "call.responded",
+      requestId: "req-parent",
+      output: "done",
+      timestamp: "2026-01-01T00:00:02Z",
+    };
+    const graph = FlowGraph.fromCallEvents([req1, req2, resp]);
+    expect(graph.order).toBe(2);
+    expect(graph.hasEdge("req-parent", "req-child")).toBe(true);
+    const parentAttrs = graph.getNodeAttributes("req-parent") as Record<string, unknown>;
+    expect(parentAttrs.status).toBe("completed");
+    const childAttrs = graph.getNodeAttributes("req-child") as Record<string, unknown>;
+    expect(childAttrs.status).toBe("pending");
+  });
+
+  it("stores identity and startedAt from call.requested", () => {
+    const event: CallEventMapValue = {
+      type: "call.requested",
+      requestId: "req-id",
+      operationId: "task.op",
+      input: {},
+      timestamp: "2026-01-01T00:00:00Z",
+      identity: { id: "user-1", scopes: ["read"] },
+      startedAt: "2026-01-01T00:00:01Z",
+    };
+    const graph = FlowGraph.fromCallEvents([event]);
+    const attrs = graph.getNodeAttributes("req-id") as Record<string, unknown>;
+    expect(attrs.identity).toEqual({ id: "user-1", scopes: ["read"] });
+    expect(attrs.startedAt).toBe("2026-01-01T00:00:01Z");
+  });
+
+  it("skips triggered edge if parent node does not exist", () => {
+    const orphanEvent: CallEventMapValue = {
+      type: "call.requested",
+      requestId: "req-orphan",
+      operationId: "task.child",
+      input: {},
+      timestamp: "2026-01-01T00:00:00Z",
+      parentRequestId: "req-nonexistent",
+    };
+    const graph = FlowGraph.fromCallEvents([orphanEvent]);
+    expect(graph.order).toBe(1);
+    expect(graph.hasNode("req-orphan")).toBe(true);
+    expect(graph.size).toBe(0);
+  });
+});
+
+describe("FlowGraph.updateFromEvent", () => {
+  it("processes single event for real-time pattern", () => {
+    const graph = new FlowGraph();
+    graph.updateFromEvent({
+      type: "call.requested",
+      requestId: "req-1",
+      operationId: "task.classify",
+      input: { text: "hello" },
+      timestamp: "2026-01-01T00:00:00Z",
+    });
+    expect(graph.hasNode("req-1")).toBe(true);
+
+    graph.updateFromEvent({
+      type: "call.responded",
+      requestId: "req-1",
+      output: { label: "hi" },
+      timestamp: "2026-01-01T00:00:02Z",
+    });
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+    expect(attrs.output).toEqual({ label: "hi" });
+  });
+
+  it("ignores events for unknown requestId", () => {
+    const graph = new FlowGraph();
+    graph.updateFromEvent({
+      type: "call.responded",
+      requestId: "unknown",
+      output: "x",
+      timestamp: "2026-01-01T00:00:00Z",
+    });
+    expect(graph.order).toBe(0);
+  });
+
+  it("ignores terminal event re-processing", () => {
+    const graph = new FlowGraph();
+    graph.updateFromEvent({
+      type: "call.requested",
+      requestId: "req-1",
+      operationId: "task.op",
+      input: {},
+      timestamp: "2026-01-01T00:00:00Z",
+    });
+    graph.updateFromEvent({
+      type: "call.responded",
+      requestId: "req-1",
+      output: "done",
+      timestamp: "2026-01-01T00:00:01Z",
+    });
+    graph.updateFromEvent({
+      type: "call.error",
+      requestId: "req-1",
+      error: { code: "X", message: "Y" },
+      timestamp: "2026-01-01T00:00:02Z",
+    });
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+  });
+});
+
+describe("FlowGraph.addCall", () => {
+  it("adds a call node", () => {
+    const graph = new FlowGraph();
+    graph.addCall({
+      requestId: "req-1",
+      operationId: "task.classify",
+      status: "pending",
+      input: { text: "hello" },
+    });
+    expect(graph.hasNode("req-1")).toBe(true);
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("pending");
+  });
+
+  it("adds triggered edge when parentRequestId is present", () => {
+    const graph = new FlowGraph();
+    graph.addCall({
+      requestId: "req-parent",
+      operationId: "task.parent",
+      status: "pending",
+      input: {},
+    });
+    graph.addCall({
+      requestId: "req-child",
+      operationId: "task.child",
+      status: "pending",
+      input: {},
+      parentRequestId: "req-parent",
+    });
+    expect(graph.hasEdge("req-parent", "req-child")).toBe(true);
+    const edgeAttrs = graph.getEdgeAttributes("req-parent", "req-child") as Record<string, unknown>;
+    expect(edgeAttrs.edgeType).toBe("triggered");
+  });
+
+  it("is idempotent — duplicate addCall is ignored", () => {
+    const graph = new FlowGraph();
+    graph.addCall({
+      requestId: "req-1",
+      operationId: "task.op",
+      status: "pending",
+      input: {},
+    });
+    graph.addCall({
+      requestId: "req-1",
+      operationId: "task.op",
+      status: "pending",
+      input: {},
+    });
+    expect(graph.order).toBe(1);
+  });
+
+  it("does not throw if parentRequestId node does not exist", () => {
+    const graph = new FlowGraph();
+    graph.addCall({
+      requestId: "req-child",
+      operationId: "task.child",
+      status: "pending",
+      input: {},
+      parentRequestId: "nonexistent",
+    });
+    expect(graph.hasNode("req-child")).toBe(true);
+    expect(graph.size).toBe(0);
+  });
+});
+
+describe("FlowGraph.addDependency", () => {
+  it("creates depends_on edge", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.a", status: "pending", input: {} });
+    graph.addCall({ requestId: "req-2", operationId: "task.b", status: "pending", input: {} });
+    graph.addDependency("req-1", "req-2");
+    const edgeKey = "req-1->req-2:depends_on";
+    expect(graph.graph.hasEdge(edgeKey)).toBe(true);
+    const attrs = graph.graph.getEdgeAttributes(edgeKey) as Record<string, unknown>;
+    expect(attrs.edgeType).toBe("depends_on");
+  });
+
+  it("is idempotent — duplicate addDependency is ignored", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.a", status: "pending", input: {} });
+    graph.addCall({ requestId: "req-2", operationId: "task.b", status: "pending", input: {} });
+    graph.addDependency("req-1", "req-2");
+    graph.addDependency("req-1", "req-2");
+    expect(graph.graph.hasEdge("req-1->req-2:depends_on")).toBe(true);
+  });
+
+  it("throws NodeNotFoundError if source doesn't exist", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-2", operationId: "task.b", status: "pending", input: {} });
+    expect(() => graph.addDependency("missing", "req-2")).toThrow(NodeNotFoundError);
+  });
+
+  it("throws NodeNotFoundError if target doesn't exist", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.a", status: "pending", input: {} });
+    expect(() => graph.addDependency("req-1", "missing")).toThrow(NodeNotFoundError);
+  });
+
+  it("throws CycleError if adding would create cycle", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.a", status: "pending", input: {} });
+    graph.addCall({ requestId: "req-2", operationId: "task.b", status: "pending", input: {} });
+    graph.addCall({ requestId: "req-3", operationId: "task.c", status: "pending", input: {} });
+    graph.addEdge("req-1", "req-2");
+    graph.addEdge("req-2", "req-3");
+    expect(() => graph.addDependency("req-3", "req-1")).toThrow(CycleError);
+  });
+});
+
+describe("FlowGraph.updateStatus", () => {
+  it("transitions pending to running", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("running");
+  });
+
+  it("transitions running to completed", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "completed", { completedAt: "2026-01-01T00:00:01Z" });
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:01Z");
+  });
+
+  it("transitions running to failed", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "failed");
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("failed");
+  });
+
+  it("transitions pending to aborted", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "aborted");
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("aborted");
+  });
+
+  it("transitions running to aborted", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "aborted");
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("aborted");
+  });
+
+  it("is no-op if status is already the target", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "pending");
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("pending");
+  });
+
+  it("throws InvalidTransitionError for completed to running", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "completed", { completedAt: "2026-01-01T00:00:01Z" });
+    expect(() => graph.updateStatus("req-1", "running")).toThrow(InvalidTransitionError);
+  });
+
+  it("throws InvalidTransitionError for failed to running", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "failed");
+    expect(() => graph.updateStatus("req-1", "running")).toThrow(InvalidTransitionError);
+  });
+
+  it("throws InvalidTransitionError for aborted to running", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "aborted");
+    expect(() => graph.updateStatus("req-1", "running")).toThrow(InvalidTransitionError);
+  });
+
+  it("throws InvalidTransitionError for pending to completed", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    expect(() => graph.updateStatus("req-1", "completed")).toThrow(InvalidTransitionError);
+  });
+
+  it("throws InvalidTransitionError for pending to failed", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    expect(() => graph.updateStatus("req-1", "failed")).toThrow(InvalidTransitionError);
+  });
+
+  it("throws NodeNotFoundError for unknown requestId", () => {
+    const graph = new FlowGraph();
+    expect(() => graph.updateStatus("missing", "running")).toThrow(NodeNotFoundError);
+  });
+
+  it("InvalidTransitionError contains from/to info", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "completed", { completedAt: "2026-01-01T00:00:01Z" });
+    try {
+      graph.updateStatus("req-1", "running");
+      expect.unreachable("should throw");
+    } catch (e) {
+      expect(e).toBeInstanceOf(InvalidTransitionError);
+      const ite = e as InvalidTransitionError;
+      expect(ite.requestId).toBe("req-1");
+      expect(ite.from).toBe("completed" as CallStatus);
+      expect(ite.to).toBe("running" as CallStatus);
+    }
+  });
+
+  it("merges extra attributes on transition", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.op", status: "pending", input: {} });
+    graph.updateStatus("req-1", "running");
+    graph.updateStatus("req-1", "completed", {
+      output: { result: 42 },
+      completedAt: "2026-01-01T00:00:01Z",
+    });
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.status).toBe("completed");
+    expect(attrs.output).toEqual({ result: 42 });
+    expect(attrs.completedAt).toBe("2026-01-01T00:00:01Z");
+  });
+});
+
+describe("FlowGraph.updateCall", () => {
+  it("partially merges call attributes", () => {
+    const graph = new FlowGraph();
+    graph.addCall({
+      requestId: "req-1",
+      operationId: "task.op",
+      status: "pending",
+      input: {},
+    });
+    graph.updateCall("req-1", { output: "some result" });
+    const attrs = graph.getNodeAttributes("req-1") as Record<string, unknown>;
+    expect(attrs.output).toBe("some result");
+    expect(attrs.status).toBe("pending");
+  });
+
+  it("throws NodeNotFoundError for unknown requestId", () => {
+    const graph = new FlowGraph();
+    expect(() => graph.updateCall("missing", { output: "x" })).toThrow(NodeNotFoundError);
+  });
+});
+
+describe("FlowGraph.removeCall", () => {
+  it("removes node and attached edges", () => {
+    const graph = new FlowGraph();
+    graph.addCall({ requestId: "req-1", operationId: "task.parent", status: "pending", input: {} });
+    graph.addCall({ requestId: "req-2", operationId: "task.child", status: "pending", input: {}, parentRequestId: "req-1" });
+    expect(graph.size).toBe(1);
+    graph.removeCall("req-2");
+    expect(graph.hasNode("req-2")).toBe(false);
+    expect(graph.size).toBe(0);
+    expect(graph.hasNode("req-1")).toBe(true);
+  });
+
+  it("is a no-op if requestId doesn't exist", () => {
+    const graph = new FlowGraph();
+    expect(() => graph.removeCall("missing")).not.toThrow();
+  });
 });

test/graph/serialization.test.ts

@@ -0,0 +1,232 @@
+import { describe, it, expect } from "vitest";
+import { Type } from "@alkdev/typebox";
+import { FlowGraph } from "../../src/graph/construction.js";
+import type { OperationSpec } from "../../src/graph/construction.js";
+import { InvalidInputError, CycleError } from "../../src/error/index.js";
+
+describe("FlowGraph.export", () => {
+  it("returns graphology native JSON format for empty graph", () => {
+    const fg = new FlowGraph();
+    const data = fg.export();
+    expect(data.options).toEqual({ type: "directed", multi: false, allowSelfLoops: false });
+    expect(data.attributes).toEqual({});
+    expect(data.nodes).toEqual([]);
+    expect(data.edges).toEqual([]);
+  });
+
+  it("returns graphology native JSON format for operation graph", () => {
+    const specs: OperationSpec[] = [
+      { name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) },
+      { name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) },
+    ];
+    const graph = FlowGraph.fromSpecs(specs);
+    const data = graph.export();
+    expect(data.options.type).toBe("directed");
+    expect(data.nodes.length).toBe(2);
+    expect(data.edges.length).toBeGreaterThan(0);
+  });
+});
+
+describe("FlowGraph.toJSON", () => {
+  it("is an alias for export", () => {
+    const fg = new FlowGraph();
+    fg.addNode("a", { name: "a" } as never);
+    const exported = fg.export();
+    const jsoned = fg.toJSON();
+    expect(jsoned).toEqual(exported);
+  });
+});
+
+describe("FlowGraph.toString", () => {
+  it("returns JSON.stringify of export()", () => {
+    const fg = new FlowGraph();
+    fg.addNode("a", { name: "a" } as never);
+    expect(fg.toString()).toBe(JSON.stringify(fg.export()));
+  });
+
+  it("round-trips through JSON.parse", () => {
+    const fg = new FlowGraph();
+    fg.addNode("a", { name: "a" } as never);
+    const parsed = JSON.parse(fg.toString());
+    expect(parsed.options).toEqual({ type: "directed", multi: false, allowSelfLoops: false });
+  });
+});
+
+describe("FlowGraph.fromJSON", () => {
+  it("round-trips fromSpecs -> export -> fromJSON", () => {
+    const specs: OperationSpec[] = [
+      { name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) },
+      { name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) },
+    ];
+    const original = FlowGraph.fromSpecs(specs);
+    const data = original.export();
+    const restored = FlowGraph.fromJSON(data);
+    expect(restored.order).toBe(original.order);
+    expect(restored.size).toBe(original.size);
+    for (const node of original.nodes()) {
+      expect(restored.hasNode(node)).toBe(true);
+      const origAttrs = original.getNodeAttributes(node as never) as Record<string, unknown>;
+      const restAttrs = restored.getNodeAttributes(node as never) as Record<string, unknown>;
+      expect(restAttrs.name).toBe(origAttrs.name);
+      expect(restAttrs.namespace).toBe(origAttrs.namespace);
+    }
+    for (const edge of original.edges()) {
+      const source = edge.split("->")[0]!;
+      const target = edge.split("->")[1]!;
+      expect(restored.hasEdge(source, target)).toBe(true);
+    }
+  });
+
+  it("round-trips empty graph", () => {
+    const fg = new FlowGraph();
+    const data = fg.export();
+    const restored = FlowGraph.fromJSON(data);
+    expect(restored.order).toBe(0);
+    expect(restored.size).toBe(0);
+    expect(restored.export()).toEqual(data);
+  });
+
+  it("throws InvalidInputError on invalid input", () => {
+    expect(() => FlowGraph.fromJSON({})).toThrow(InvalidInputError);
+  });
+
+  it("InvalidInputError contains errors array", () => {
+    try {
+      FlowGraph.fromJSON({});
+      expect.unreachable("should throw");
+    } catch (e) {
+      expect(e).toBeInstanceOf(InvalidInputError);
+      const err = e as InvalidInputError;
+      expect(err.errors.length).toBeGreaterThan(0);
+    }
+  });
+
+  it("throws InvalidInputError on missing nodes", () => {
+    const bad = {
+      options: { type: "directed", multi: false, allowSelfLoops: false },
+      attributes: {},
+      edges: [],
+    };
+    expect(() => FlowGraph.fromJSON(bad as never)).toThrow(InvalidInputError);
+  });
+
+  it("throws CycleError on cyclic input", () => {
+    const cyclicData = {
+      options: { type: "directed", multi: false, allowSelfLoops: false },
+      attributes: {},
+      nodes: [
+        { key: "a", attributes: { requestId: "a", operationId: "op.a", status: "completed", input: {} } },
+        { key: "b", attributes: { requestId: "b", operationId: "op.b", status: "completed", input: {} } },
+      ],
+      edges: [
+        { key: "a->b", source: "a", target: "b", attributes: {} },
+        { key: "b->a", source: "b", target: "a", attributes: {} },
+      ],
+    };
+    expect(() => FlowGraph.fromJSON(cyclicData as never)).toThrow(CycleError);
+  });
+
+  it("CycleError contains cycle paths on cyclic input", () => {
+    const cyclicData = {
+      options: { type: "directed", multi: false, allowSelfLoops: false },
+      attributes: {},
+      nodes: [
+        { key: "a", attributes: { requestId: "a", operationId: "op.a", status: "completed", input: {} } },
+        { key: "b", attributes: { requestId: "b", operationId: "op.b", status: "completed", input: {} } },
+      ],
+      edges: [
+        { key: "a->b", source: "a", target: "b", attributes: {} },
+        { key: "b->a", source: "b", target: "a", attributes: {} },
+      ],
+    };
+    try {
+      FlowGraph.fromJSON(cyclicData as never);
+      expect.unreachable("should throw");
+    } catch (e) {
+      expect(e).toBeInstanceOf(CycleError);
+      const ce = e as CycleError;
+      expect(ce.cycles.length).toBeGreaterThan(0);
+    }
+  });
+
+  it("preserves node attributes through round-trip", () => {
+    const specs: OperationSpec[] = [
+      { name: "classify", namespace: "task", version: "2.0.0", type: "mutation", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }), description: "Classifies text", tags: ["nlp"] },
+    ];
+    const original = FlowGraph.fromSpecs(specs);
+    const data = original.export();
+    const restored = FlowGraph.fromJSON(data);
+    const origAttrs = original.getNodeAttributes("task.classify" as never) as Record<string, unknown>;
+    const restAttrs = restored.getNodeAttributes("task.classify" as never) as Record<string, unknown>;
+    expect(restAttrs.name).toBe(origAttrs.name);
+    expect(restAttrs.namespace).toBe(origAttrs.namespace);
+    expect(restAttrs.version).toBe(origAttrs.version);
+    expect(restAttrs.type).toBe(origAttrs.type);
+    expect(restAttrs.description).toBe(origAttrs.description);
+    expect(restAttrs.tags).toEqual(origAttrs.tags);
+  });
+
+  it("preserves edge attributes through round-trip", () => {
+    const specs: OperationSpec[] = [
+      { name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) },
+      { name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) },
+    ];
+    const original = FlowGraph.fromSpecs(specs);
+    const data = original.export();
+    const restored = FlowGraph.fromJSON(data);
+    const origEdgeAttrs = original.getEdgeAttributes("task.extract", "task.classify") as Record<string, unknown>;
+    const restEdgeAttrs = restored.getEdgeAttributes("task.extract", "task.classify") as Record<string, unknown>;
+    expect(restEdgeAttrs.edgeType).toBe(origEdgeAttrs.edgeType);
+    expect(restEdgeAttrs.compatible).toBe(origEdgeAttrs.compatible);
+  });
+
+  it("double round-trip is lossless", () => {
+    const specs: OperationSpec[] = [
+      { name: "extract", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ raw: Type.String() }), outputSchema: Type.Object({ text: Type.String() }) },
+      { name: "classify", namespace: "task", version: "1.0.0", type: "query", inputSchema: Type.Object({ text: Type.String() }), outputSchema: Type.Object({ label: Type.String() }) },
+    ];
+    const original = FlowGraph.fromSpecs(specs);
+    const first = original.export();
+    const restored1 = FlowGraph.fromJSON(first);
+    const second = restored1.export();
+    const restored2 = FlowGraph.fromJSON(second);
+    const third = restored2.export();
+    expect(third).toEqual(first);
+    expect(third).toEqual(second);
+  });
+
+  it("accepts valid call graph serialized data", () => {
+    const callData = {
+      options: { type: "directed", multi: false, allowSelfLoops: false },
+      attributes: {},
+      nodes: [
+        {
+          key: "req_1",
+          attributes: {
+            requestId: "req_1",
+            operationId: "task.classify",
+            status: "completed",
+            input: { text: "hello" },
+            output: { label: "greeting" },
+          },
+        },
+      ],
+      edges: [],
+    };
+    const fg = FlowGraph.fromJSON(callData as never);
+    expect(fg.order).toBe(1);
+    expect(fg.hasNode("req_1")).toBe(true);
+  });
+
+  it("throws InvalidInputError for invalid node attributes", () => {
+    const bad = {
+      options: { type: "directed", multi: false, allowSelfLoops: false },
+      attributes: {},
+      nodes: [
+        { key: "a", attributes: { invalid: true } },
+      ],
+      edges: [],
+    };
+    expect(() => FlowGraph.fromJSON(bad as never)).toThrow(InvalidInputError);
+  });
+});

test/reactive/node-status.test.ts

@@ -0,0 +1,663 @@
+import { describe, it, expect } from "vitest";
+import { signal, computed } from "@preact/signals-core";
+import type { Signal, ReadonlySignal } from "@preact/signals-core";
+import { DirectedGraph } from "graphology";
+import {
+  computePreconditions,
+  computeBlockedByFailure,
+  registerStartEffect,
+  registerAbortEffect,
+} from "../../src/reactive/node-status.js";
+import type { NodeStatusContext } from "../../src/reactive/node-status.js";
+import { WorkflowReactiveRoot } from "../../src/reactive/workflow.js";
+import type { NodeStatus } from "../../src/schema/enums.js";
+
+function makeContext(
+  statusMap: Map<string, Signal<NodeStatus>>,
+  predecessors: string[],
+): NodeStatusContext {
+  return { statusMap, predecessors };
+}
+
+function makeStatusMap(
+  entries: [string, NodeStatus][],
+): Map<string, Signal<NodeStatus>> {
+  const map = new Map<string, Signal<NodeStatus>>();
+  for (const [key, value] of entries) {
+    map.set(key, signal<NodeStatus>(value));
+  }
+  return map;
+}
+
+describe("computePreconditions", () => {
+  it("returns true for root node with no predecessors", () => {
+    const statusMap = makeStatusMap([]);
+    const ctx = makeContext(statusMap, []);
+    expect(computePreconditions("a", ctx)).toBe(true);
+  });
+
+  it("returns false when predecessor is idle", () => {
+    const statusMap = makeStatusMap([["a", "idle"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+
+  it("returns true when all predecessors are completed", () => {
+    const statusMap = makeStatusMap([["a", "completed"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(true);
+  });
+
+  it("returns true when all predecessors are skipped", () => {
+    const statusMap = makeStatusMap([["a", "skipped"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(true);
+  });
+
+  it("returns true when predecessors are mix of completed and skipped", () => {
+    const statusMap = makeStatusMap([
+      ["a", "completed"],
+      ["b", "skipped"],
+    ]);
+    const ctx = makeContext(statusMap, ["a", "b"]);
+    expect(computePreconditions("c", ctx)).toBe(true);
+  });
+
+  it("returns false when predecessor is failed", () => {
+    const statusMap = makeStatusMap([["a", "failed"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+
+  it("returns false when predecessor is aborted", () => {
+    const statusMap = makeStatusMap([["a", "aborted"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+
+  it("returns false when one of multiple predecessors is failed", () => {
+    const statusMap = makeStatusMap([
+      ["a", "completed"],
+      ["b", "failed"],
+    ]);
+    const ctx = makeContext(statusMap, ["a", "b"]);
+    expect(computePreconditions("c", ctx)).toBe(false);
+  });
+
+  it("returns false when predecessor is running", () => {
+    const statusMap = makeStatusMap([["a", "running"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+
+  it("returns false when predecessor is waiting", () => {
+    const statusMap = makeStatusMap([["a", "waiting"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+
+  it("returns false for missing predecessor in statusMap", () => {
+    const statusMap = makeStatusMap([]);
+    const ctx = makeContext(statusMap, ["unknown"]);
+    expect(computePreconditions("b", ctx)).toBe(false);
+  });
+});
+
+describe("computeBlockedByFailure", () => {
+  it("returns false for root node with no predecessors", () => {
+    const statusMap = makeStatusMap([]);
+    const ctx = makeContext(statusMap, []);
+    expect(computeBlockedByFailure("a", ctx)).toBe(false);
+  });
+
+  it("returns true when predecessor is failed", () => {
+    const statusMap = makeStatusMap([["a", "failed"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computeBlockedByFailure("b", ctx)).toBe(true);
+  });
+
+  it("returns true when predecessor is aborted", () => {
+    const statusMap = makeStatusMap([["a", "aborted"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computeBlockedByFailure("b", ctx)).toBe(true);
+  });
+
+  it("returns false when predecessor is completed", () => {
+    const statusMap = makeStatusMap([["a", "completed"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computeBlockedByFailure("b", ctx)).toBe(false);
+  });
+
+  it("returns false when predecessor is skipped", () => {
+    const statusMap = makeStatusMap([["a", "skipped"]]);
+    const ctx = makeContext(statusMap, ["a"]);
+    expect(computeBlockedByFailure("b", ctx)).toBe(false);
+  });
+
+  it("returns true when any of multiple predecessors is failed", () => {
+    const statusMap = makeStatusMap([
+      ["a", "completed"],
+      ["b", "failed"],
+    ]);
+    const ctx = makeContext(statusMap, ["a", "b"]);
+    expect(computeBlockedByFailure("c", ctx)).toBe(true);
+  });
+
+  it("returns false when all predecessors are completed", () => {
+    const statusMap = makeStatusMap([
+      ["a", "completed"],
+      ["b", "completed"],
+    ]);
+    const ctx = makeContext(statusMap, ["a", "b"]);
+    expect(computeBlockedByFailure("c", ctx)).toBe(false);
+  });
+
+  it("returns false for missing predecessor in statusMap", () => {
+    const statusMap = makeStatusMap([]);
+    const ctx = makeContext(statusMap, ["unknown"]);
+    expect(computeBlockedByFailure("b", ctx)).toBe(false);
+  });
+});
+
+describe("registerStartEffect", () => {
+  it("transitions idle node to ready when preconditions are true", () => {
+    const status = signal<NodeStatus>("idle");
+    const preconditions = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("ready");
+
+    for (const d of disposers) d();
+  });
+
+  it("transitions waiting node to ready when preconditions are true", () => {
+    const status = signal<NodeStatus>("waiting");
+    const preconditions = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("ready");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition running node when preconditions become true", () => {
+    const status = signal<NodeStatus>("running");
+    const preconditions = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("running");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition completed node when preconditions become true", () => {
+    const status = signal<NodeStatus>("completed");
+    const preconditions = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("completed");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition idle node when preconditions are false", () => {
+    const status = signal<NodeStatus>("idle");
+    const preconditions = computed(() => false);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("idle");
+
+    for (const d of disposers) d();
+  });
+
+  it("reactively transitions to ready when preconditions change from false to true", () => {
+    const trigger = signal<NodeStatus>("idle");
+    const preconditions = computed(() => trigger.value === "completed");
+    const status = signal<NodeStatus>("idle");
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(status.value).toBe("idle");
+
+    trigger.value = "completed";
+
+    expect(status.value).toBe("ready");
+
+    for (const d of disposers) d();
+  });
+});
+
+describe("registerAbortEffect", () => {
+  it("transitions idle node to aborted when blockedByFailure is true", () => {
+    const status = signal<NodeStatus>("idle");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers);
+
+    expect(status.value).toBe("aborted");
+
+    for (const d of disposers) d();
+  });
+
+  it("transitions waiting node to aborted when blockedByFailure is true", () => {
+    const status = signal<NodeStatus>("waiting");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers);
+
+    expect(status.value).toBe("aborted");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition ready node with default policy", () => {
+    const status = signal<NodeStatus>("ready");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers);
+
+    expect(status.value).toBe("ready");
+
+    for (const d of disposers) d();
+  });
+
+  it("transitions ready node to aborted with abortDependents option", () => {
+    const status = signal<NodeStatus>("ready");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers, {
+      abortDependents: true,
+    });
+
+    expect(status.value).toBe("aborted");
+
+    for (const d of disposers) d();
+  });
+
+  it("transitions running node to aborted with abortDependents option", () => {
+    const status = signal<NodeStatus>("running");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers, {
+      abortDependents: true,
+    });
+
+    expect(status.value).toBe("aborted");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition completed node even with abortDependents", () => {
+    const status = signal<NodeStatus>("completed");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers, {
+      abortDependents: true,
+    });
+
+    expect(status.value).toBe("completed");
+
+    for (const d of disposers) d();
+  });
+
+  it("does not transition failed node even with abortDependents", () => {
+    const status = signal<NodeStatus>("failed");
+    const blockedByFailure = computed(() => true);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers, {
+      abortDependents: true,
+    });
+
+    expect(status.value).toBe("failed");
+
+    for (const d of disposers) d();
+  });
+
+  it("reactively transitions to aborted when blockedByFailure changes", () => {
+    const trigger = signal<NodeStatus>("idle");
+    const blockedByFailure = computed(
+      () => trigger.value === "failed" || trigger.value === "aborted",
+    );
+    const status = signal<NodeStatus>("idle");
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers);
+
+    expect(status.value).toBe("idle");
+
+    trigger.value = "failed";
+
+    expect(status.value).toBe("aborted");
+
+    for (const d of disposers) d();
+  });
+});
+
+describe("sequential preconditions via WorkflowReactiveRoot", () => {
+  function makeSeqGraph(): DirectedGraph {
+    const graph = new DirectedGraph();
+    graph.addNode("a", { name: "a" });
+    graph.addNode("b", { name: "b" });
+    graph.addNode("c", { name: "c" });
+    graph.addEdgeWithKey("a->b", "a", "b", { edgeType: "sequential" });
+    graph.addEdgeWithKey("b->c", "b", "c", { edgeType: "sequential" });
+    return graph;
+  }
+
+  it("root node transitions to ready (no predecessors)", () => {
+    const graph = makeSeqGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    expect(root.statusMap.get("a")!.value).toBe("ready");
+
+    root.dispose();
+  });
+
+  it("downstream nodes stay idle until predecessor completes", () => {
+    const graph = makeSeqGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    expect(root.statusMap.get("b")!.value).toBe("idle");
+
+    root.dispose();
+  });
+
+  it("downstream node transitions to ready after predecessor completes", () => {
+    const graph = makeSeqGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("a")!.value = "completed";
+
+    expect(root.statusMap.get("b")!.value).toBe("ready");
+
+    root.dispose();
+  });
+
+  it("full sequential chain transitions", () => {
+    const graph = makeSeqGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("a")!.value = "completed";
+    expect(root.statusMap.get("b")!.value).toBe("ready");
+
+    root.statusMap.get("b")!.value = "completed";
+    expect(root.statusMap.get("c")!.value).toBe("ready");
+
+    root.dispose();
+  });
+});
+
+describe("parallel preconditions via WorkflowReactiveRoot", () => {
+  function makeParallelGraph(): DirectedGraph {
+    const graph = new DirectedGraph();
+    graph.addNode("top", { name: "top" });
+    graph.addNode("left", { name: "left" });
+    graph.addNode("right", { name: "right" });
+    graph.addEdgeWithKey("top->left", "top", "left", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("top->right", "top", "right", {
+      edgeType: "sequential",
+    });
+    return graph;
+  }
+
+  it("parallel siblings both become ready when parent completes", () => {
+    const graph = makeParallelGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+
+    expect(root.statusMap.get("left")!.value).toBe("ready");
+    expect(root.statusMap.get("right")!.value).toBe("ready");
+
+    root.dispose();
+  });
+
+  it("parallel siblings are independent - failure on one does not abort the other", () => {
+    const graph = makeParallelGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "ready";
+    root.statusMap.get("right")!.value = "ready";
+
+    root.statusMap.get("left")!.value = "failed";
+
+    expect(root.statusMap.get("left")!.value).toBe("failed");
+    expect(root.statusMap.get("right")!.value).toBe("ready");
+
+    root.dispose();
+  });
+});
+
+describe("join (fork-join) preconditions via WorkflowReactiveRoot", () => {
+  function makeDiamondGraph(): DirectedGraph {
+    const graph = new DirectedGraph();
+    graph.addNode("top", { name: "top" });
+    graph.addNode("left", { name: "left" });
+    graph.addNode("right", { name: "right" });
+    graph.addNode("bottom", { name: "bottom" });
+    graph.addEdgeWithKey("top->left", "top", "left", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("top->right", "top", "right", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("left->bottom", "left", "bottom", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("right->bottom", "right", "bottom", {
+      edgeType: "sequential",
+    });
+    return graph;
+  }
+
+  it("join node stays idle until all predecessors complete", () => {
+    const graph = makeDiamondGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "completed";
+
+    expect(root.statusMap.get("bottom")!.value).toBe("idle");
+
+    root.dispose();
+  });
+
+  it("join node becomes ready when all predecessors are completed", () => {
+    const graph = makeDiamondGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "completed";
+    root.statusMap.get("right")!.value = "completed";
+
+    expect(root.statusMap.get("bottom")!.value).toBe("ready");
+
+    root.dispose();
+  });
+
+  it("join node blocked when one predecessor fails", () => {
+    const graph = makeDiamondGraph();
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "completed";
+    root.statusMap.get("right")!.value = "failed";
+
+    expect(root.preconditions.get("bottom")!.value).toBe(false);
+    expect(root.statusMap.get("bottom")!.value).toBe("aborted");
+
+    root.dispose();
+  });
+});
+
+describe("blockedByFailure cascade via WorkflowReactiveRoot", () => {
+  it("failure cascades through multiple downstream nodes", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("a", { name: "a" });
+    graph.addNode("b", { name: "b" });
+    graph.addNode("c", { name: "c" });
+    graph.addEdgeWithKey("a->b", "a", "b", { edgeType: "sequential" });
+    graph.addEdgeWithKey("b->c", "b", "c", { edgeType: "sequential" });
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("a")!.value = "failed";
+
+    expect(root.statusMap.get("b")!.value).toBe("aborted");
+    expect(root.statusMap.get("c")!.value).toBe("aborted");
+
+    root.dispose();
+  });
+
+  it("aborted predecessor causes cascade just like failed", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("a", { name: "a" });
+    graph.addNode("b", { name: "b" });
+    graph.addEdgeWithKey("a->b", "a", "b", { edgeType: "sequential" });
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("a")!.value = "aborted";
+
+    expect(root.statusMap.get("b")!.value).toBe("aborted");
+
+    root.dispose();
+  });
+});
+
+describe("skipped satisfies preconditions via WorkflowReactiveRoot", () => {
+  it("skipped predecessor satisfies preconditions for downstream node", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("a", { name: "a" });
+    graph.addNode("b", { name: "b" });
+    graph.addEdgeWithKey("a->b", "a", "b", { edgeType: "sequential" });
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("a")!.value = "skipped";
+
+    expect(root.preconditions.get("b")!.value).toBe(true);
+    expect(root.statusMap.get("b")!.value).toBe("ready");
+
+    root.dispose();
+  });
+});
+
+describe("failure isolation in parallel branches via WorkflowReactiveRoot", () => {
+  it("failure in one branch does not abort sibling branch", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("top", { name: "top" });
+    graph.addNode("left", { name: "left" });
+    graph.addNode("right", { name: "right" });
+    graph.addNode("bottom", { name: "bottom" });
+    graph.addEdgeWithKey("top->left", "top", "left", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("top->right", "top", "right", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("left->bottom", "left", "bottom", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("right->bottom", "right", "bottom", {
+      edgeType: "sequential",
+    });
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "running";
+    root.statusMap.get("right")!.value = "failed";
+
+    expect(root.statusMap.get("left")!.value).toBe("running");
+    expect(root.statusMap.get("bottom")!.value).toBe("aborted");
+
+    root.dispose();
+  });
+
+  it("completed branch is not affected by failure in other branch", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("top", { name: "top" });
+    graph.addNode("left", { name: "left" });
+    graph.addNode("right", { name: "right" });
+    graph.addNode("bottom", { name: "bottom" });
+    graph.addEdgeWithKey("top->left", "top", "left", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("top->right", "top", "right", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("left->bottom", "left", "bottom", {
+      edgeType: "sequential",
+    });
+    graph.addEdgeWithKey("right->bottom", "right", "bottom", {
+      edgeType: "sequential",
+    });
+    const root = new WorkflowReactiveRoot(graph);
+
+    root.statusMap.get("top")!.value = "completed";
+    root.statusMap.get("left")!.value = "completed";
+    root.statusMap.get("right")!.value = "failed";
+
+    expect(root.statusMap.get("left")!.value).toBe("completed");
+
+    root.dispose();
+  });
+});
+
+describe("effect disposal", () => {
+  it("start effect is tracked by effectDisposers and cleaned up", () => {
+    const status = signal<NodeStatus>("idle");
+    const preconditions = computed(() => false);
+    const disposers: (() => void)[] = [];
+
+    registerStartEffect(status, preconditions, disposers);
+
+    expect(disposers.length).toBe(1);
+
+    disposers[0]!();
+  });
+
+  it("abort effect is tracked by effectDisposer and cleaned up", () => {
+    const status = signal<NodeStatus>("idle");
+    const blockedByFailure = computed(() => false);
+    const disposers: (() => void)[] = [];
+
+    registerAbortEffect(status, blockedByFailure, disposers);
+
+    expect(disposers.length).toBe(1);
+
+    disposers[0]!();
+  });
+
+  it("WorkflowReactiveRoot dispose clears all effects", () => {
+    const graph = new DirectedGraph();
+    graph.addNode("a", { name: "a" });
+    graph.addNode("b", { name: "b" });
+    graph.addEdgeWithKey("a->b", "a", "b", { edgeType: "sequential" });
+    const root = new WorkflowReactiveRoot(graph);
+
+    expect(root.statusMap.get("a")!.value).toBe("ready");
+
+    root.dispose();
+
+    expect(root.statusMap.size).toBe(0);
+  });
+});

test/reactive/workflow.test.ts

@@ -48,11 +48,11 @@ function makeForkJoinGraph(): DirectedGraph {
 
 describe("WorkflowReactiveRoot", () => {
   describe("constructor and initializeSignals", () => {
-    it("initializes all nodes with idle status", () => {
+    it("root node starts as ready, downstream nodes start as idle", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      expect(root.statusMap.get("a")!.value).toBe("idle");
+      expect(root.statusMap.get("a")!.value).toBe("ready");
       expect(root.statusMap.get("b")!.value).toBe("idle");
       expect(root.statusMap.get("c")!.value).toBe("idle");
 
@@ -159,7 +159,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -177,7 +177,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -201,7 +201,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -225,7 +225,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -256,7 +256,7 @@ describe("WorkflowReactiveRoot", () => {
         timestamp: "2026-01-01T00:00:00Z",
       });
 
-      expect(root.statusMap.get("a")!.value).toBe("idle");
+      expect(root.statusMap.get("a")!.value).toBe("ready");
 
       root.dispose();
     });
@@ -265,7 +265,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
 
       const respondedEvent: CallEventMapValue = {
         type: "call.responded",
@@ -291,11 +291,11 @@ describe("WorkflowReactiveRoot", () => {
   });
 
   describe("getStatus", () => {
-    it("returns idle for nodes with no events", () => {
+    it("returns ready for root nodes with no events", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      expect(root.getStatus("a")).toBe("idle");
+      expect(root.getStatus("a")).toBe("ready");
 
       root.dispose();
     });
@@ -304,7 +304,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -322,9 +322,9 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.statusMap.get("a")!.value = "waiting";
+      root.statusMap.get("b")!.value = "waiting";
 
-      expect(root.getStatus("a")).toBe("waiting");
+      expect(root.getStatus("b")).toBe("waiting");
 
       root.dispose();
     });
@@ -353,7 +353,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -380,7 +380,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -408,7 +408,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -434,7 +434,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -452,7 +452,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-2");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -466,6 +466,7 @@ describe("WorkflowReactiveRoot", () => {
         error: { code: "ERR", message: "first attempt failed" },
         timestamp: "2026-01-01T00:00:01Z",
       });
+      root.setRequestId("a", "req-2");
       root.append({
         type: "call.requested",
         requestId: "req-2",
@@ -503,7 +504,7 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-1");
+      root.setRequestId("a", "req-1");
       root.append({
         type: "call.requested",
         requestId: "req-1",
@@ -840,11 +841,11 @@ describe("WorkflowReactiveRoot", () => {
       const graph = makeSimpleGraph();
       const root = new WorkflowReactiveRoot(graph);
 
-      root.nodeKeyToRequestId.set("a", "req-a");
-      root.nodeKeyToRequestId.set("b", "req-b");
-      root.nodeKeyToRequestId.set("c", "req-c");
+      root.setRequestId("a", "req-a");
+      root.setRequestId("b", "req-b");
+      root.setRequestId("c", "req-c");
 
-      expect(root.getStatus("a")).toBe("idle");
+      expect(root.getStatus("a")).toBe("ready");
       expect(root.getStatus("b")).toBe("idle");
       expect(root.getStatus("c")).toBe("idle");