Function idx853_supervised_autowatch_check

tests/test_mcp.c:9766–9838

helper used only by the POSIX fork harness below */

#ifndef _WIN32 /* helper used only by the POSIX fork harness below */
static int idx853_supervised_autowatch_check(const char *repo_dir, const char *cache_dir) {
    /* Become a supervisor host with the kill switch OFF — the real prod MCP
     * server's state. Done in the FORKED CHILD only (see harness) so the parent
     * test-runner's process-wide host mark stays clear (#845 invariant). Bound the
     * worker so a stuck spawn cannot run long under the fork+alarm net. */
    cbm_index_supervisor_mark_host();
    cbm_unsetenv("CBM_INDEX_SUPERVISOR");
    cbm_setenv("CBM_INDEX_MAX_RESTARTS", "1", 1);
    cbm_setenv("CBM_INDEX_WORKER_TIMEOUT_S", "30", 1);

    cbm_config_t *cfg = cbm_config_open(cache_dir);
    cbm_store_t *wstore = cbm_store_open_memory();
    cbm_watcher_t *watcher = wstore ? cbm_watcher_new(wstore, NULL, NULL) : NULL;
    if (!cfg || !watcher) {
        if (watcher) {
            cbm_watcher_free(watcher);
        }
        if (wstore) {
            cbm_store_close(wstore);
        }
        if (cfg) {
            cbm_config_close(cfg);
        }
        return IDX853_SETUP_FAIL;
    }
    /* auto_index=true → maybe_auto_index launches autoindex_thread for the fresh
     * project; auto_watch=false → the gate this guard exercises. */
    cbm_config_set(cfg, CBM_CONFIG_AUTO_INDEX, "true");
    cbm_config_set(cfg, CBM_CONFIG_AUTO_WATCH, "false");

    /* detect_session derives session_root/session_project from the cwd. */
    char old_cwd[1024];
    if (!cbm_getcwd(old_cwd, sizeof(old_cwd)) || cbm_chdir(repo_dir) != 0) {
        cbm_watcher_free(watcher);
        cbm_store_close(wstore);
        cbm_config_close(cfg);
        return IDX853_SETUP_FAIL;
    }

    int spawns_before = cbm_index_supervisor_spawn_count();
    int code = IDX853_SETUP_FAIL;

    cbm_mcp_server_t *srv = cbm_mcp_server_new(NULL);
    if (srv) {
        cbm_mcp_server_set_watcher(srv, watcher);
        cbm_mcp_server_set_config(srv, cfg);
        char *resp = cbm_mcp_server_handle(
            srv, "{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{}}");
        free(resp);
        /* free() joins the autoindex thread → the supervised worker has finished
         * and the registration decision (buggy or gated) has executed. */
        cbm_mcp_server_free(srv);

        int spawns_after = cbm_index_supervisor_spawn_count();
        int watch_count = cbm_watcher_watch_count(watcher);

        if (spawns_after == spawns_before) {
            code = IDX853_NO_SPAWN; /* supervised branch never ran — not a valid probe */