feat: inject thread progress into agent prompt (#127)

Agents now receive a Thread Progress section showing current step number
and role visit count, eliminating tool calls to count turns.

- util-agent: new buildThreadProgress() helper
- agent-hermes: inject before continuation/first-visit prompt
- agent-claude-code: same injection point

Fixes #127

packages/util-agent/src/build-thread-progress.ts

@@ -0,0 +1,27 @@
+import type { StepContext } from "@united-workforce/protocol";
+
+/**
+ * Build a compact thread-progress summary so the agent knows where it is
+ * in the conversation without making tool calls to count steps.
+ *
+ * Example output:
+ *   ## Thread Progress
+ *   Thread step 6. You (proponent) have spoken 2 times before this turn.
+ */
+export function buildThreadProgress(steps: StepContext[], role: string): string {
+  const totalSteps = steps.length;
+  const roleVisits = steps.filter((s) => s.role === role).length;
+
+  const parts = [`## Thread Progress`];
+  if (totalSteps === 0) {
+    parts.push(
+      `This is the first step of the thread. You (${role}) are speaking for the first time.`,
+    );
+  } else {
+    parts.push(
+      `Thread step ${totalSteps + 1}. You (${role}) have spoken ${roleVisits} time${roleVisits === 1 ? "" : "s"} before this turn.`,
+    );
+  }
+
+  return parts.join("\n");
+}

packages/util-agent/src/index.ts

@@ -1,6 +1,7 @@
 export { buildContinuationPrompt } from "./build-continuation-prompt.js";
 export { buildOutputFormatInstruction } from "./build-output-format-instruction.js";
 export { buildRolePrompt } from "./build-role-prompt.js";
+export { buildThreadProgress } from "./build-thread-progress.js";
 export type { BuildContextMeta } from "./context.js";
 export { buildContext, buildContextWithMeta } from "./context.js";
 export type { ExtractResult, ResolvedLlmProvider } from "./extract.js";