Phase 7: MCP handler (25 tests), NIP-04 encrypt/decrypt (15 tests), CVM server skeleton

- mcp_handler.c/h: 4 tools (get_config, set_config, get_balance, wallet_send)
- nip04.c/h: AES-256-CBC + ECDH with 0x02 compressed pubkey prefix
  - Fixed IV copy bug: mbedTLS AES-CBC modifies IV in-place
  - Base64 encode/decode for ciphertext transport
  - PKCS7 padding
- cvm_server.c/h: Nostr DM listener with FreeRTOS task
- config: cvm_enabled, cvm_relays fields
- 156 total tests passing across 10 test binaries

1 files changed, 148 insertions, 0 deletions

diff --git a/tests/unit/test_mcp_handler.c b/tests/unit/test_mcp_handler.c
new file mode 100644
index 0000000..aaa199d
--- /dev/null
+++ b/tests/unit/test_mcp_handler.c
@@ -0,0 +1,148 @@
+#include "test_framework.h"
+#include "mcp_handler.h"
+#include "config.h"
+#include "nucula_wallet.h"
+#include "cJSON.h"
+#include <string.h>
+#include <stdio.h>
+
+static tollgate_config_t g_test_config;
+static uint64_t g_wallet_balance = 0;
+static int g_wallet_proof_count = 0;
+static int g_wallet_send_rc = 0;
+static char g_wallet_send_token[256] = "cashuA_test_token";
+
+const tollgate_config_t *tollgate_config_get(void) {
+    return &g_test_config;
+}
+
+uint64_t nucula_wallet_balance(void) {
+    return g_wallet_balance;
+}
+
+int nucula_wallet_proof_count(void) {
+    return g_wallet_proof_count;
+}
+
+int nucula_wallet_send(uint64_t amount, char *token_out, size_t token_max) {
+    (void)amount;
+    (void)token_max;
+    if (g_wallet_send_rc == 0) {
+        strncpy(token_out, g_wallet_send_token, token_max - 1);
+    }
+    return g_wallet_send_rc;
+}
+
+static void test_mcp_parse_tool(void)
+{
+    printf("\n=== MCP tool parsing ===\n");
+    ASSERT_EQ_INT(MCP_TOOL_GET_CONFIG, mcp_parse_tool("get_config"), "get_config");
+    ASSERT_EQ_INT(MCP_TOOL_SET_CONFIG, mcp_parse_tool("set_config"), "set_config");
+    ASSERT_EQ_INT(MCP_TOOL_GET_BALANCE, mcp_parse_tool("get_balance"), "get_balance");
+    ASSERT_EQ_INT(MCP_TOOL_WALLET_SEND, mcp_parse_tool("wallet_send"), "wallet_send");
+    ASSERT_EQ_INT(MCP_TOOL_UNKNOWN, mcp_parse_tool("foo"), "unknown tool");
+    ASSERT_EQ_INT(MCP_TOOL_UNKNOWN, mcp_parse_tool(NULL), "NULL tool");
+}
+
+static void test_mcp_get_config(void)
+{
+    printf("\n=== MCP get_config ===\n");
+    memset(&g_test_config, 0, sizeof(g_test_config));
+    strncpy(g_test_config.ap_ssid, "TollGate-TEST", sizeof(g_test_config.ap_ssid) - 1);
+    strncpy(g_test_config.metric, "bytes", sizeof(g_test_config.metric) - 1);
+    g_test_config.price_per_step = 21;
+    g_test_config.step_size_ms = 60000;
+    g_test_config.step_size_bytes = 22020096;
+    strncpy(g_test_config.mint_url, "https://testnut.cashu.space", sizeof(g_test_config.mint_url) - 1);
+
+    mcp_response_t resp = mcp_handle_get_config();
+    ASSERT(resp.success, "get_config succeeds");
+
+    cJSON *result = cJSON_Parse(resp.result_json);
+    ASSERT(result != NULL, "result is valid JSON");
+    ASSERT_EQ_STR("bytes", cJSON_GetObjectItem(result, "metric")->valuestring, "metric=bytes");
+    ASSERT_EQ_INT(21, cJSON_GetObjectItem(result, "price_per_step")->valueint, "price=21");
+    cJSON_Delete(result);
+}
+
+static void test_mcp_set_config(void)
+{
+    printf("\n=== MCP set_config ===\n");
+    memset(&g_test_config, 0, sizeof(g_test_config));
+    g_test_config.price_per_step = 21;
+
+    const char *params = "{\"price_per_step\":42,\"metric\":\"milliseconds\"}";
+    mcp_response_t resp = mcp_handle_set_config(params);
+    ASSERT(resp.success, "set_config succeeds");
+    ASSERT_EQ_INT(42, g_test_config.price_per_step, "price updated to 42");
+    ASSERT_EQ_STR("milliseconds", g_test_config.metric, "metric updated");
+
+    resp = mcp_handle_set_config("not json");
+    ASSERT(!resp.success, "invalid JSON fails");
+}
+
+static void test_mcp_get_balance(void)
+{
+    printf("\n=== MCP get_balance ===\n");
+    g_wallet_balance = 500;
+    g_wallet_proof_count = 8;
+
+    mcp_response_t resp = mcp_handle_get_balance();
+    ASSERT(resp.success, "get_balance succeeds");
+
+    cJSON *result = cJSON_Parse(resp.result_json);
+    ASSERT(result != NULL, "result is valid JSON");
+    ASSERT_EQ_INT(500, (int)cJSON_GetObjectItem(result, "balance_sats")->valuedouble, "balance=500");
+    ASSERT_EQ_INT(8, cJSON_GetObjectItem(result, "proof_count")->valueint, "proofs=8");
+    cJSON_Delete(result);
+}
+
+static void test_mcp_wallet_send(void)
+{
+    printf("\n=== MCP wallet_send ===\n");
+    g_wallet_send_rc = 0;
+    strncpy(g_wallet_send_token, "cashuA_send_test", sizeof(g_wallet_send_token) - 1);
+
+    const char *params = "{\"amount\":21}";
+    mcp_response_t resp = mcp_handle_wallet_send(params);
+    ASSERT(resp.success, "wallet_send succeeds");
+
+    cJSON *result = cJSON_Parse(resp.result_json);
+    ASSERT(result != NULL, "result is valid JSON");
+    ASSERT_EQ_STR("cashuA_send_test", cJSON_GetObjectItem(result, "token")->valuestring, "token matches");
+    cJSON_Delete(result);
+
+    printf("\n--- wallet_send missing amount ---\n");
+    resp = mcp_handle_wallet_send("{}");
+    ASSERT(!resp.success, "missing amount fails");
+
+    printf("\n--- wallet_send send fails ---\n");
+    g_wallet_send_rc = -1;
+    resp = mcp_handle_wallet_send("{\"amount\":100}");
+    ASSERT(!resp.success, "send failure reported");
+}
+
+static void test_mcp_dispatch(void)
+{
+    printf("\n=== MCP dispatch ===\n");
+    mcp_request_t req = {0};
+    req.tool = MCP_TOOL_UNKNOWN;
+    strncpy(req.method, "bogus", sizeof(req.method) - 1);
+    mcp_response_t resp = mcp_dispatch(&req);
+    ASSERT(!resp.success, "unknown tool dispatch fails");
+
+    resp = mcp_dispatch(NULL);
+    ASSERT(!resp.success, "NULL request dispatch fails");
+}
+
+int main(void)
+{
+    printf("=== test_mcp_handler ===\n");
+    test_mcp_parse_tool();
+    test_mcp_get_config();
+    test_mcp_set_config();
+    test_mcp_get_balance();
+    test_mcp_wallet_send();
+    test_mcp_dispatch();
+    TEST_SUMMARY();
+}