diff --git a/packages/cli-json-cas/src/cli.test.ts b/packages/cli-json-cas/src/cli.test.ts
index 90146d5..51186cf 100644
--- a/packages/cli-json-cas/src/cli.test.ts
+++ b/packages/cli-json-cas/src/cli.test.ts
@@ -315,6 +315,207 @@ describe("ucas render command", () => {
   });
 });
 
+describe("Schema Hash Validation in put command", () => {
+  test("put with non-existent literal hash should fail", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr, exitCode } = await runCliAlias(
+      "put",
+      "AAAAAAAAAAAAA",
+      payloadFile,
+    );
+
+    expect(exitCode).not.toBe(0);
+    expect(stderr).toContain("Schema not found: AAAAAAAAAAAAA");
+  });
+
+  test("put with different non-existent literal hash should fail", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr, exitCode } = await runCliAlias(
+      "put",
+      "ZZZZZZZZZZZZZ",
+      payloadFile,
+    );
+
+    expect(exitCode).not.toBe(0);
+    expect(stderr).toContain("Schema not found: ZZZZZZZZZZZZZ");
+  });
+
+  test("put with malformed hash should fail", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr, exitCode } = await runCliAlias(
+      "put",
+      "INVALID_HASH",
+      payloadFile,
+    );
+
+    expect(exitCode).not.toBe(0);
+    expect(stderr.length).toBeGreaterThan(0);
+  });
+
+  test("put with non-existent @alias should fail with clear message", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr, exitCode } = await runCliAlias(
+      "put",
+      "@nonexistent",
+      payloadFile,
+    );
+
+    expect(exitCode).not.toBe(0);
+    expect(stderr).toContain("Schema not found");
+    expect(stderr).toContain("@nonexistent");
+  });
+
+  test("put with valid @string alias should succeed (regression)", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify("hello"));
+
+    const { stdout, stderr, exitCode } = await runCliAlias(
+      "put",
+      "@string",
+      payloadFile,
+    );
+
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(stdout).toMatch(/^[0-9A-HJKMNP-TV-Z]{13}$/);
+  });
+
+  test("put with valid @number alias should succeed (regression)", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, "42");
+
+    const { stdout, stderr, exitCode } = await runCliAlias(
+      "put",
+      "@number",
+      payloadFile,
+    );
+
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(stdout).toMatch(/^[0-9A-HJKMNP-TV-Z]{13}$/);
+  });
+
+  test("put with valid @object alias should succeed (regression)", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ key: "value" }));
+
+    const { stdout, stderr, exitCode } = await runCliAlias(
+      "put",
+      "@object",
+      payloadFile,
+    );
+
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(stdout).toMatch(/^[0-9A-HJKMNP-TV-Z]{13}$/);
+  });
+
+  test("put with explicit valid schema hash should succeed (regression)", async () => {
+    await runCliAlias("init");
+
+    // First, create a custom schema
+    const schemaFile = join(testDir, "schema.json");
+    writeFileSync(
+      schemaFile,
+      JSON.stringify({
+        type: "object",
+        properties: { name: { type: "string" } },
+      }),
+    );
+    const { stdout: schemaHash } = await runCliAlias(
+      "schema",
+      "put",
+      schemaFile,
+    );
+
+    // Now create a node with that schema
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ name: "test" }));
+
+    const { stdout, stderr, exitCode } = await runCliAlias(
+      "put",
+      schemaHash.trim(),
+      payloadFile,
+    );
+
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(stdout).toMatch(/^[0-9A-HJKMNP-TV-Z]{13}$/);
+  });
+
+  test("all bootstrap schema aliases should work (regression)", async () => {
+    await runCliAlias("init");
+
+    const aliases = ["@string", "@number", "@object", "@array", "@bool"];
+    const payloads = [
+      JSON.stringify("test"),
+      "123",
+      JSON.stringify({}),
+      JSON.stringify([]),
+      "true",
+    ];
+
+    for (let i = 0; i < aliases.length; i++) {
+      const payloadFile = join(testDir, `payload-${i}.json`);
+      writeFileSync(payloadFile, payloads[i] ?? "");
+
+      const { exitCode } = await runCliAlias(
+        "put",
+        aliases[i] ?? "",
+        payloadFile,
+      );
+
+      expect(exitCode).toBe(0);
+    }
+  });
+
+  test("error message should preserve original input (hash)", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr } = await runCliAlias("put", "AAAAAAAAAAAAA", payloadFile);
+
+    // Error should show the original hash, not a resolved version
+    expect(stderr).toContain("AAAAAAAAAAAAA");
+  });
+
+  test("error message should preserve original input (alias)", async () => {
+    await runCliAlias("init");
+
+    const payloadFile = join(testDir, "payload.json");
+    writeFileSync(payloadFile, JSON.stringify({ test: "data" }));
+
+    const { stderr } = await runCliAlias("put", "@invalid", payloadFile);
+
+    // Error should show the original alias, not a resolved hash
+    expect(stderr).toContain("@invalid");
+  });
+});
+
 describe("Suite 6: CLI Integration with Templates", () => {
   test("6.1 CLI with Template (Default Parameters)", async () => {
     const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
diff --git a/packages/cli-json-cas/src/index.ts b/packages/cli-json-cas/src/index.ts
index 51bdf4d..158e6a1 100644
--- a/packages/cli-json-cas/src/index.ts
+++ b/packages/cli-json-cas/src/index.ts
@@ -294,6 +294,12 @@ async function cmdPut(args: string[]): Promise<void> {
   const typeHash = await resolveTypeHash(typeHashOrAlias);
   const payload = readJsonFile(file);
   const store = openStore();
+
+  // Check if schema exists before storing
+  if (!store.has(typeHash)) {
+    die(`Schema not found: ${typeHashOrAlias}`);
+  }
+
   const hash = await store.put(typeHash, payload);
   console.log(hash);
 }