feat: new planty package

packages/planty/src/lib/dialog-runner.ts

@@ -0,0 +1,52 @@
+import type { Choice, DialogNode, PlantyConfig } from './types.js';
+
+export class DialogRunner {
+  private config: PlantyConfig;
+
+  constructor(config: PlantyConfig) {
+    this.config = config;
+  }
+
+  getNode(id: string): DialogNode | null {
+    return this.config.nodes[id] ?? null;
+  }
+
+  getStartNode(): { id: string; node: DialogNode } | null {
+    const node = this.getNode(this.config.start);
+    if (!node) return null;
+    return { id: this.config.start, node };
+  }
+
+  getNextNode(currentId: string): { id: string; node: DialogNode } | null {
+    const current = this.getNode(currentId);
+    if (!current) return null;
+    if (!current.next) return null;
+    const next = this.getNode(current.next);
+    if (!next) return null;
+    return { id: current.next, node: next };
+  }
+
+  followChoice(choice: Choice): { id: string; node: DialogNode } | null {
+    if (!choice.next) return null;
+    const node = this.getNode(choice.next);
+    if (!node) return null;
+    return { id: choice.next, node };
+  }
+
+  /** Walk the main path (first choice for choice nodes) and return all node IDs. */
+  getMainPath(): string[] {
+    const path: string[] = [];
+    const visited = new Set<string>();
+    let id: string | null = this.config.start;
+    while (id && !visited.has(id)) {
+      visited.add(id);
+      path.push(id);
+      const node = this.getNode(id);
+      if (!node) break;
+      const next = node.choices?.[0]?.next ?? node.next;
+      if (next) id = next;
+      else break;
+    }
+    return path;
+  }
+}