fix(auth): persist agent token signing key

tests/unit/agent-auth.test.ts

@@ -0,0 +1,45 @@
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { afterEach, describe, expect, it } from "vitest";
+import {
+  createAgentToken,
+  initializeAgentTokenSigningKey,
+  validateAgentToken,
+} from "../../src/main/agent-auth";
+import { FatalError } from "../../src/main/errors";
+
+const tempDirs: string[] = [];
+
+async function createTempDir() {
+  const dir = await mkdtemp(join(tmpdir(), "agentcompany-agent-auth-"));
+  tempDirs.push(dir);
+  return dir;
+}
+
+afterEach(async () => {
+  await Promise.all(tempDirs.splice(0).map((dir) => rm(dir, { recursive: true, force: true })));
+});
+
+describe("agent token signing key", () => {
+  it("keeps existing run tokens valid across profile reinitialization", async () => {
+    const profileDir = await createTempDir();
+    initializeAgentTokenSigningKey(profileDir);
+    const token = createAgentToken("agent-1", "company-1", "run-1");
+
+    initializeAgentTokenSigningKey(profileDir);
+
+    expect(validateAgentToken(token)).toMatchObject({
+      agentId: "agent-1",
+      companyId: "company-1",
+      runId: "run-1",
+    });
+  });
+
+  it("treats a corrupt signing key as fatal state", async () => {
+    const profileDir = await createTempDir();
+    await writeFile(join(profileDir, "agent-api-signing.key"), Buffer.from("too-short"));
+
+    expect(() => initializeAgentTokenSigningKey(profileDir)).toThrow(FatalError);
+  });
+});