diff --git a/packages/cli/src/config/env.ts b/packages/cli/src/config/env.ts
new file mode 100644
index 0000000..9e7b8cd
--- /dev/null
+++ b/packages/cli/src/config/env.ts
@@ -0,0 +1,6 @@
+export const STELLAR_EXPLAIN_TOKEN_ENV = "STELLAR_EXPLAIN_TOKEN";
+
+export function getEnvApiToken(env: NodeJS.ProcessEnv = process.env): string | undefined {
+  const token = env[STELLAR_EXPLAIN_TOKEN_ENV]?.trim();
+  return token || undefined;
+}
diff --git a/packages/cli/src/index.ts b/packages/cli/src/index.ts
index 168856b..442fb64 100644
--- a/packages/cli/src/index.ts
+++ b/packages/cli/src/index.ts
@@ -8,7 +8,7 @@ import { registerHealth } from "./commands/health.js";
 import { registerBatch } from "./commands/batch.js";
 import { registerExplain } from "./commands/explain.js";
 import { registerWatch } from "./commands/watch.js";
-import { registerCompletion } from "./commands/completion.js";
+import { registerCompletionCommand } from "./commands/completion.js";
 import { registerConfigSet } from "./commands/configSet.js";
 import { registerConfigGet } from "./commands/configGet.js";
 import { registerConfigList } from "./commands/configList.js";
@@ -19,36 +19,9 @@ import { readConfigFile } from "./lib/configFile.js";
 import { getCliVersion } from "./lib/pkgVersion.js";
 
 const program = new Command();
+const version = getCliVersion();
 
 program
-  .name('stellar-explain')
-  .description('CLI for exploring and explaining Stellar transactions and accounts')
-  .version('0.1.0');
-
-// ── Existing commands (stubs shown; replace with real implementations) ────────
-
-program
-  .command('tx <hash>')
-  .description('Look up and explain a Stellar transaction')
-  .action((hash: string) => {
-    addEntry('tx', hash);
-    // TODO: delegate to tx command handler
-    console.log(`Looking up transaction: ${hash}`);
-  });
-
-program
-  .command('account <id>')
-  .description('Look up and explain a Stellar account')
-  .action((id: string) => {
-    addEntry('account', id);
-    // TODO: delegate to account command handler
-    console.log(`Looking up account: ${id}`);
-  });
-
-registerHistoryCommand(program);    // #441 / #442 / #443
-registerCompletionCommand(program); // #440
-
-program.parse(process.argv);
   .name(BIN_NAME)
   .version(version)
   .option("--url <url>", "API base URL")
@@ -75,7 +48,7 @@ registerHealth(program);
 registerBatch(program);
 registerExplain(program);
 registerWatch(program);
-registerCompletion(program);
+registerCompletionCommand(program);
 registerConfigSet(program);
 registerConfigGet(program);
 registerConfigList(program);
diff --git a/packages/cli/src/lib/client.ts b/packages/cli/src/lib/client.ts
index 0581453..c0e8791 100644
--- a/packages/cli/src/lib/client.ts
+++ b/packages/cli/src/lib/client.ts
@@ -4,12 +4,14 @@ import type {
   AccountExplanation,
   HealthResponse,
 } from "../types/index.js";
+import { getEnvApiToken } from "../config/env.js";
 
 export interface ClientOptions {
   baseUrl: string;
   timeout: number;  // #276
   verbose: boolean; // #277
   retries: number; // #414
+  apiToken?: string;
 }
 
 async function requestOnce<T>(
@@ -19,9 +21,11 @@ async function requestOnce<T>(
   const controller = new AbortController();
   const timer = setTimeout(() => controller.abort(), opts.timeout);
   const start = Date.now();
+  const apiToken = opts.apiToken ?? getEnvApiToken();
+  const headers = apiToken ? { Authorization: `Bearer ${apiToken}` } : undefined;
 
   try {
-    const res = await fetch(url, { signal: controller.signal });
+    const res = await fetch(url, { signal: controller.signal, headers });
     const duration = Date.now() - start;
 
     if (opts.verbose) {
diff --git a/packages/cli/tests/client.test.ts b/packages/cli/tests/client.test.ts
index 815065f..cfd02ec 100644
--- a/packages/cli/tests/client.test.ts
+++ b/packages/cli/tests/client.test.ts
@@ -27,6 +27,7 @@ describe("createClient", () => {
 
   afterEach(() => {
     vi.restoreAllMocks();
+    vi.unstubAllEnvs();
   });
 
   // ── Success cases ──────────────────────────────────────────────
@@ -90,6 +91,37 @@ describe("createClient", () => {
         expect.objectContaining({ signal: expect.any(AbortSignal) }),
       );
     });
+
+    it("sends STELLAR_EXPLAIN_TOKEN as a Bearer token", async () => {
+      vi.stubEnv("STELLAR_EXPLAIN_TOKEN", "secret-token");
+      vi.stubGlobal("fetch", mockFetchResponse(200, { status: "ok" }));
+
+      const client = createClient(defaultOpts);
+      await client.getHealth();
+
+      expect(fetch).toHaveBeenCalledWith(
+        "http://localhost:4000/health",
+        expect.objectContaining({
+          headers: { Authorization: "Bearer secret-token" },
+          signal: expect.any(AbortSignal),
+        }),
+      );
+    });
+
+    it("prefers an explicit apiToken over STELLAR_EXPLAIN_TOKEN", async () => {
+      vi.stubEnv("STELLAR_EXPLAIN_TOKEN", "env-token");
+      vi.stubGlobal("fetch", mockFetchResponse(200, { status: "ok" }));
+
+      const client = createClient({ ...defaultOpts, apiToken: "option-token" });
+      await client.getHealth();
+
+      expect(fetch).toHaveBeenCalledWith(
+        "http://localhost:4000/health",
+        expect.objectContaining({
+          headers: { Authorization: "Bearer option-token" },
+        }),
+      );
+    });
   });
 
   // ── 404 Not Found ──────────────────────────────────────────────