feat: add load_primary_config(), myconf_fini(); remove static cf global from myconf.c

- load_primary_config(): resolves conf/current, reads raw bytes, computes
  SHA-256 tag, decodes Cap'n Proto via load_cluster_config_from_file(),
  checks reserved names, sets config_generation, checks staleness
- myconf_fini(): frees conffile and cluster_config (calls free_ClusterConfig)
- Remove static cf global from myconf.c; get_default_conf() now uses a
  local struct cluster_configuration* via load_cluster_config()
- Add load_primary_config_for_test() under XCE_TESTING in config_repl.c
  to test path resolution without triggering FATAL
- Add xce/cluster_def.h include to config_repl.c and test_config_repl.c
  so cluster_t is complete when XCE_TESTING is active
- TDD: test_load_primary_config_missing_returns_error passes (18/18)

src/controller/testsuite/test_config_repl.c

@@ -16,6 +16,7 @@
 
 #include "config_repl.h"
 #include "myconf.h"
+#include "xce/cluster_def.h"
 
 /* Per-test directory helpers — not Unity setUp/tearDown (those are in
  * controller_test.c). Each test that needs a temp dir calls cr_setup()
@@ -24,6 +25,9 @@
 static char g_tmpdir[256];
 static char g_conf_dir[300];
 
+/* tmpdir string for load_primary_config tests (no conf/current) */
+static char tmpdir[256];
+
 static void cr_setup(void)
 {
     snprintf(g_tmpdir, sizeof(g_tmpdir), "/tmp/test_cr_%d_%ld",
@@ -367,6 +371,44 @@ static void test_sanitise_cn_truncated(void)
     printf("test_sanitise_cn_truncated: PASS\n");
 }
 
+/* ── load_primary_config (via test-only helper) ── */
+
+#ifdef XCE_TESTING
+static void test_load_primary_config_missing_returns_error(void)
+{
+    /* Create a minimal cluster_t with no conf/current file */
+    cluster_t c;
+    memset(&c, 0, sizeof(c));
+    myconf_t myconf;
+    memset(&myconf, 0, sizeof(myconf));
+
+    /* Use a fresh tmpdir with no conf/current */
+    snprintf(tmpdir, sizeof(tmpdir), "/tmp/test_lpc_%d_%ld",
+             (int)getpid(), (long)time(NULL));
+    mkdir(tmpdir, 0700);
+
+    myconf.workdir            = tmpdir;
+    myconf.name               = "ctrl0";
+    myconf.conf_keep_n        = 2;
+    myconf.conf_stale_timeout = 86400;
+    myconf.conffile           = NULL;
+    c.myconf                  = &myconf;
+
+    /* No conf/current exists — must fail (not FATAL in test context) */
+    int rc = load_primary_config_for_test(&c);
+    TEST_ASSERT_TRUE(rc < 0);
+    /* conffile must still be NULL (no heap allocation on failure) */
+    TEST_ASSERT_NULL(myconf.conffile);
+
+    /* Cleanup */
+    char cmd[512];
+    snprintf(cmd, sizeof(cmd), "rm -rf %s", tmpdir);
+    system(cmd);
+
+    printf("test_load_primary_config_missing_returns_error: PASS\n");
+}
+#endif
+
 /* ── dispatch ───────────────────────────────────── */
 
 void test_config_repl(void)
@@ -388,4 +430,7 @@ void test_config_repl(void)
     RUN_TEST(test_sanitise_cn_printable);
     RUN_TEST(test_sanitise_cn_control_chars);
     RUN_TEST(test_sanitise_cn_truncated);
+#ifdef XCE_TESTING
+    RUN_TEST(test_load_primary_config_missing_returns_error);
+#endif
 }