feat: replace edgePrompt null check with isFirstVisit (Phase 2)

- Add isFirstVisit: boolean to AgentContext
- Compute from steps history: !steps.some(s => s.role === role)
- hermes.ts: use isFirstVisit for first-entry vs re-entry logic
- buildInitialPrompt: always append edgePrompt as Moderator Instruction
- edgePrompt is never blanked — always the real moderator instruction
- New tests for first-visit, re-entry, and fallback scenarios

Refs #405, #407, #404

packages/workflow-agent-kit/src/context.ts

@@ -142,6 +142,7 @@ export async function buildContext(threadId: ThreadId, role: string): Promise<Ag
 
   const steps = await buildHistory(store, chain.stepsNewestFirst);
   const edgePrompt = readEdgePrompt();
+  const isFirstVisit = !steps.some((s) => s.role === role);
 
   return {
     threadId,
@@ -152,6 +153,7 @@ export async function buildContext(threadId: ThreadId, role: string): Promise<Ag
     store,
     outputFormatInstruction: "",
     edgePrompt,
+    isFirstVisit,
   };
 }
 
@@ -189,6 +191,7 @@ export async function buildContextWithMeta(
 
   const steps = await buildHistory(store, chain.stepsNewestFirst);
   const edgePrompt = readEdgePrompt();
+  const isFirstVisit = !steps.some((s) => s.role === role);
 
   return {
     threadId,
@@ -199,6 +202,7 @@ export async function buildContextWithMeta(
     store,
     outputFormatInstruction: "",
     edgePrompt,
+    isFirstVisit,
     meta: { storageRoot, store, schemas, headHash, chain },
   };
 }

packages/workflow-agent-kit/src/types.ts

@@ -14,9 +14,13 @@ export type AgentContext = ModeratorContext & {
   outputFormatInstruction: string;
   /**
    * Edge prompt from the graph transition that led to this role (UWF_EDGE_PROMPT).
-   * Phase 2 will use visit history to choose full role definition vs continuation.
+   * Always the real moderator instruction for this step.
    */
   edgePrompt: string;
+  /**
+   * True when the current role has not appeared in steps history before this invocation.
+   */
+  isFirstVisit: boolean;
 };
 
 export type AgentRunResult = {