Next development steps

5 files changed, 1093 insertions, 7 deletions

diff --git a/src/core/chess.c b/src/core/chess.c
new file mode 100644
index 0000000..94d35a6
--- /dev/null
+++ b/src/core/chess.c
@@ -0,0 +1,668 @@
+#if defined(__linux__)
+#define _DEFAULT_SOURCE
+#endif
+
+#include "hybbx/chess.h"
+#include "hybbx/session.h"
+#include "hybbx/service.h"
+#include "hybbx/log.h"
+#include "hybbx/util.h"
+#include "hybbx/config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+static chess_game_t g_games[CHESS_GAME_MAX];
+static unsigned g_max_games = CHESS_DEFAULT_MAX;
+
+/* ── Board init ────────────────────────────────────────────── */
+
+static void board_init(chess_board_t *b)
+{
+    static const char back[] = "RNBQKBNR";
+    unsigned f;
+
+    memset(b, 0, sizeof(*b));
+    for (f = 0; f < 8; f++) {
+        b->sq[0][f] = back[f];
+        b->sq[1][f] = 'P';
+        b->sq[6][f] = 'p';
+        b->sq[7][f] = (char)tolower((unsigned char)back[f]);
+    }
+    for (unsigned r = 2; r < 6; r++)
+        for (f = 0; f < 8; f++)
+            b->sq[r][f] = CHESS_EMPTY;
+}
+
+void hybbx_chess_init(void)
+{
+    memset(g_games, 0, sizeof(g_games));
+    g_max_games = CHESS_DEFAULT_MAX;
+}
+
+void hybbx_chess_shutdown(void)
+{
+    unsigned i;
+    for (i = 0; i < g_max_games; i++)
+        g_games[i].active = 0;
+}
+
+void hybbx_chess_config_apply(const struct hybbx_config *config)
+{
+    unsigned val;
+
+    if (config != NULL) {
+        val = hybbx_config_get_uint(config, "chess", "max_games",
+                                     CHESS_DEFAULT_MAX, 1, CHESS_GAME_MAX);
+    } else {
+        val = CHESS_DEFAULT_MAX;
+    }
+    g_max_games = val;
+    hybbx_log_info("[chess] max_games=%u", g_max_games);
+}
+
+unsigned hybbx_chess_max_games(void)
+{
+    return g_max_games;
+}
+
+/* ── Helpers ───────────────────────────────────────────────── */
+
+static int parse_square(const char *s, unsigned *rank, unsigned *file)
+{
+    if (s == NULL || strlen(s) < 2)
+        return 0;
+    if (s[0] < 'a' || s[0] > 'h' || s[1] < '1' || s[1] > '8')
+        return 0;
+    *file = (unsigned)(s[0] - 'a');
+    *rank = (unsigned)(s[1] - '1');
+    return 1;
+}
+
+static chess_color_t piece_color(char p)
+{
+    if (p == CHESS_EMPTY) return CHESS_COLOR_NONE;
+    return (p >= 'A' && p <= 'Z') ? CHESS_WHITE : CHESS_BLACK;
+}
+
+static char piece_upper(char p)
+{
+    return (char)toupper((unsigned char)p);
+}
+
+static int in_bounds(unsigned r, unsigned f)
+{
+    return r < 8 && f < 8;
+}
+
+/* ── Check detection ───────────────────────────────────────── */
+
+static int square_attacked_by(const chess_board_t *b, unsigned rank,
+                              unsigned file, chess_color_t by)
+{
+    unsigned r, f;
+    int dr, df;
+    char pawn, knight, bishop, rook, queen, king;
+
+    if (by == CHESS_WHITE) {
+        pawn = 'P'; knight = 'N'; bishop = 'B';
+        rook = 'R'; queen = 'Q'; king = 'K';
+    } else {
+        pawn = 'p'; knight = 'n'; bishop = 'b';
+        rook = 'r'; queen = 'q'; king = 'k';
+    }
+
+    /* Pawn attacks */
+    if (by == CHESS_WHITE) {
+        if (rank > 0 && file > 0 && b->sq[rank - 1][file - 1] == pawn) return 1;
+        if (rank > 0 && file < 7 && b->sq[rank - 1][file + 1] == pawn) return 1;
+    } else {
+        if (rank < 7 && file > 0 && b->sq[rank + 1][file - 1] == pawn) return 1;
+        if (rank < 7 && file < 7 && b->sq[rank + 1][file + 1] == pawn) return 1;
+    }
+
+    /* Knight */
+    {
+        static const int kr[] = {2,2,-2,-2,1,1,-1,-1};
+        static const int kf[] = {1,-1,1,-1,2,-2,2,-2};
+        for (unsigned i = 0; i < 8; i++) {
+            int nr = (int)rank + kr[i], nf = (int)file + kf[i];
+            if (nr >= 0 && nr < 8 && nf >= 0 && nf < 8)
+                if (b->sq[nr][nf] == knight) return 1;
+        }
+    }
+
+    /* Sliding: bishop/queen diagonals */
+    {
+        static const int drs[] = {1,1,-1,-1};
+        static const int dfs[] = {1,-1,1,-1};
+        for (unsigned d = 0; d < 4; d++) {
+            dr = drs[d]; df = dfs[d];
+            r = rank; f = file;
+            while (1) {
+                r = (unsigned)((int)r + dr);
+                f = (unsigned)((int)f + df);
+                if (!in_bounds(r, f)) break;
+                if (b->sq[r][f] != CHESS_EMPTY) {
+                    if (b->sq[r][f] == bishop || b->sq[r][f] == queen) return 1;
+                    break;
+                }
+            }
+        }
+    }
+
+    /* Sliding: rook/queen straights */
+    {
+        static const int drs[] = {1,-1,0,0};
+        static const int dfs[] = {0,0,1,-1};
+        for (unsigned d = 0; d < 4; d++) {
+            dr = drs[d]; df = dfs[d];
+            r = rank; f = file;
+            while (1) {
+                r = (unsigned)((int)r + dr);
+                f = (unsigned)((int)f + df);
+                if (!in_bounds(r, f)) break;
+                if (b->sq[r][f] != CHESS_EMPTY) {
+                    if (b->sq[r][f] == rook || b->sq[r][f] == queen) return 1;
+                    break;
+                }
+            }
+        }
+    }
+
+    /* King */
+    {
+        static const int drs[] = {1,1,1,0,0,-1,-1,-1};
+        static const int dfs[] = {1,0,-1,1,-1,1,0,-1};
+        for (unsigned d = 0; d < 8; d++) {
+            int nr = (int)rank + drs[d], nf = (int)file + dfs[d];
+            if (nr >= 0 && nr < 8 && nf >= 0 && nf < 8)
+                if (b->sq[nr][nf] == king) return 1;
+        }
+    }
+
+    return 0;
+}
+
+static int find_king(const chess_board_t *b, chess_color_t color,
+                     unsigned *kr, unsigned *kf)
+{
+    char king = (color == CHESS_WHITE) ? 'K' : 'k';
+    for (unsigned r = 0; r < 8; r++)
+        for (unsigned f = 0; f < 8; f++)
+            if (b->sq[r][f] == king) { *kr = r; *kf = f; return 1; }
+    return 0;
+}
+
+static int is_in_check(const chess_board_t *b, chess_color_t side)
+{
+    unsigned kr, kf;
+    chess_color_t opp = (side == CHESS_WHITE) ? CHESS_BLACK : CHESS_WHITE;
+    if (!find_king(b, side, &kr, &kf)) return 0;
+    return square_attacked_by(b, kr, kf, opp);
+}
+
+/* ── Move legality ─────────────────────────────────────────── */
+
+static int pseudo_legal_pawn(const chess_board_t *b, unsigned fr,
+                             unsigned ff, unsigned tr, unsigned tf,
+                             chess_color_t side)
+{
+    int dir = (side == CHESS_WHITE) ? 1 : -1;
+    int start_rank = (side == CHESS_WHITE) ? 1 : 6;
+    int dr = (int)tr - (int)fr;
+    int df = (int)tf - (int)ff;
+
+    if (df == 0) {
+        if (dr == dir && b->sq[tr][tf] == CHESS_EMPTY) return 1;
+        if (dr == 2 * dir && (int)fr == start_rank &&
+            b->sq[fr + (unsigned)dir][ff] == CHESS_EMPTY &&
+            b->sq[tr][tf] == CHESS_EMPTY) return 1;
+    }
+    if ((df == 1 || df == -1) && dr == dir) {
+        if (b->sq[tr][tf] != CHESS_EMPTY) return 1;
+    }
+    return 0;
+}
+
+static int pseudo_legal_knight(unsigned fr, unsigned ff, unsigned tr,
+                               unsigned tf)
+{
+    int dr = abs((int)tr - (int)fr);
+    int df = abs((int)tf - (int)ff);
+    return (dr == 2 && df == 1) || (dr == 1 && df == 2);
+}
+
+static int sliding_clear(const chess_board_t *b, unsigned fr, unsigned ff,
+                         unsigned tr, unsigned tf)
+{
+    int dr = 0, df = 0;
+    unsigned r, f;
+
+    if ((int)tr > (int)fr) dr = 1;
+    else if ((int)tr < (int)fr) dr = -1;
+    if ((int)tf > (int)ff) df = 1;
+    else if ((int)tf < (int)ff) df = -1;
+
+    r = (unsigned)((int)fr + dr);
+    f = (unsigned)((int)ff + df);
+    while (r != tr || f != tf) {
+        if (!in_bounds(r, f) || b->sq[r][f] != CHESS_EMPTY) return 0;
+        r = (unsigned)((int)r + dr);
+        f = (unsigned)((int)f + df);
+    }
+    return 1;
+}
+
+static int pseudo_legal(const chess_board_t *b, unsigned fr, unsigned ff,
+                        unsigned tr, unsigned tf, chess_color_t side)
+{
+    char piece = b->sq[fr][ff];
+    int dr = abs((int)tr - (int)fr);
+    int df = abs((int)tf - (int)ff);
+    chess_color_t target_color;
+
+    if (piece == CHESS_EMPTY) return 0;
+    if (piece_color(piece) != side) return 0;
+
+    target_color = piece_color(b->sq[tr][tf]);
+    if (target_color == side) return 0;
+
+    switch (piece_upper(piece)) {
+    case 'P': return pseudo_legal_pawn(b, fr, ff, tr, tf, side);
+    case 'N': return pseudo_legal_knight(fr, ff, tr, tf);
+    case 'B':
+        if (dr != df || dr == 0) return 0;
+        return sliding_clear(b, fr, ff, tr, tf);
+    case 'R':
+        if (fr != tr && ff != tf) return 0;
+        return sliding_clear(b, fr, ff, tr, tf);
+    case 'Q':
+        if (fr != tr && ff != tf && dr != df) return 0;
+        return sliding_clear(b, fr, ff, tr, tf);
+    case 'K':
+        return dr <= 1 && df <= 1 && (dr + df > 0);
+    }
+    return 0;
+}
+
+static int has_any_legal_move(chess_board_t *b, chess_color_t side);
+
+static int is_legal_move(chess_board_t *b, unsigned fr, unsigned ff,
+                         unsigned tr, unsigned tf, chess_color_t side)
+{
+    chess_board_t tmp;
+
+    if (!pseudo_legal(b, fr, ff, tr, tf, side)) return 0;
+
+    memcpy(&tmp, b, sizeof(tmp));
+    tmp.sq[tr][tf] = tmp.sq[fr][ff];
+    tmp.sq[fr][ff] = CHESS_EMPTY;
+
+    /* Auto-promote to queen */
+    if (piece_upper(tmp.sq[tr][tf]) == 'P') {
+        if ((side == CHESS_WHITE && tr == 7) ||
+            (side == CHESS_BLACK && tr == 0)) {
+            tmp.sq[tr][tf] = (side == CHESS_WHITE) ? 'Q' : 'q';
+        }
+    }
+
+    return !is_in_check(&tmp, side);
+}
+
+static int has_any_legal_move(chess_board_t *b, chess_color_t side)
+{
+    for (unsigned fr = 0; fr < 8; fr++)
+        for (unsigned ff = 0; ff < 8; ff++) {
+            if (piece_color(b->sq[fr][ff]) != side) continue;
+            for (unsigned tr = 0; tr < 8; tr++)
+                for (unsigned tf = 0; tf < 8; tf++)
+                    if (is_legal_move(b, fr, ff, tr, tf, side))
+                        return 1;
+        }
+    return 0;
+}
+
+/* ── SAN notation (simplified) ─────────────────────────────── */
+
+static void make_san(char *out, size_t outlen, char piece,
+                     unsigned ff, unsigned tr, unsigned tf,
+                     int capture, int check, int mate, char promote)
+{
+    char *p = out;
+    size_t room = outlen;
+
+    if (piece_upper(piece) == 'P') {
+        if (capture) {
+            int n = snprintf(p, room, "%cx%c%d", 'a' + ff, 'a' + tf, tr + 1);
+            p += n; room -= (size_t)n;
+        } else {
+            int n = snprintf(p, room, "%c%d", 'a' + tf, tr + 1);
+            p += n; room -= (size_t)n;
+        }
+    } else {
+        int n = snprintf(p, room, "%c%c%d", piece_upper(piece),
+                         'a' + tf, tr + 1);
+        p += n; room -= (size_t)n;
+    }
+    if (promote) {
+        snprintf(p, room, "=%c", piece_upper(promote));
+    } else if (mate) {
+        snprintf(p, room, "#");
+    } else if (check) {
+        snprintf(p, room, "+");
+    }
+}
+
+/* ── Game management ───────────────────────────────────────── */
+
+chess_game_t *hybbx_chess_get_game(unsigned index)
+{
+    if (index >= CHESS_GAME_MAX) return NULL;
+    return &g_games[index];
+}
+
+chess_game_t *hybbx_chess_create_game(struct hybbx_session *white,
+                                      const char *white_name)
+{
+    unsigned i;
+    for (i = 0; i < g_max_games; i++) {
+        if (!g_games[i].active) {
+            memset(&g_games[i], 0, sizeof(g_games[i]));
+            g_games[i].active = 1;
+            hybbx_strlcpy(g_games[i].white_name, white_name,
+                          sizeof(g_games[i].white_name));
+            g_games[i].white_session = white;
+            board_init(&g_games[i].board);
+            g_games[i].turn = CHESS_WHITE;
+            g_games[i].move_number = 1;
+            snprintf(g_games[i].game_id, sizeof(g_games[i].game_id),
+                     "G%u", i + 1);
+            hybbx_log_info("[chess] game %s created by %s",
+                           g_games[i].game_id, white_name);
+            return &g_games[i];
+        }
+    }
+    return NULL;
+}
+
+chess_game_t *hybbx_chess_find_open_game(void)
+{
+    unsigned i;
+    for (i = 0; i < g_max_games; i++)
+        if (g_games[i].active && g_games[i].black_session == NULL)
+            return &g_games[i];
+    return NULL;
+}
+
+chess_game_t *hybbx_chess_find_game_by_id(const char *id)
+{
+    unsigned i;
+    if (id == NULL) return NULL;
+    for (i = 0; i < g_max_games; i++)
+        if (g_games[i].active && strcasecmp(g_games[i].game_id, id) == 0)
+            return &g_games[i];
+    return NULL;
+}
+
+int hybbx_chess_join_game(chess_game_t *game, struct hybbx_session *black,
+                          const char *black_name)
+{
+    if (game == NULL || game->black_session != NULL) return 0;
+    game->black_session = black;
+    hybbx_strlcpy(game->black_name, black_name, sizeof(game->black_name));
+    hybbx_log_info("[chess] %s joined game %s as black", black_name,
+                   game->game_id);
+    return 1;
+}
+
+int hybbx_chess_add_spectator(chess_game_t *game,
+                              struct hybbx_session *spec)
+{
+    unsigned i;
+    if (game == NULL || spec == NULL) return 0;
+    if (hybbx_chess_is_player(game, spec)) return 0;
+    for (i = 0; i < game->spectator_count; i++)
+        if (game->spectators[i] == spec) return 1;
+    if (game->spectator_count >= CHESS_SPECTATOR_MAX) return 0;
+    game->spectators[game->spectator_count++] = spec;
+    return 1;
+}
+
+void hybbx_chess_remove_spectator(chess_game_t *game,
+                                  struct hybbx_session *spec)
+{
+    unsigned i;
+    if (game == NULL || spec == NULL) return;
+    for (i = 0; i < game->spectator_count; i++) {
+        if (game->spectators[i] == spec) {
+            game->spectators[i] = game->spectators[--game->spectator_count];
+            return;
+        }
+    }
+}
+
+int hybbx_chess_is_player(const chess_game_t *game,
+                          const struct hybbx_session *session)
+{
+    if (game == NULL || session == NULL) return 0;
+    return game->white_session == session || game->black_session == session;
+}
+
+int hybbx_chess_is_spectator(const chess_game_t *game,
+                             const struct hybbx_session *session)
+{
+    unsigned i;
+    if (game == NULL || session == NULL) return 0;
+    for (i = 0; i < game->spectator_count; i++)
+        if (game->spectators[i] == session) return 1;
+    return 0;
+}
+
+chess_color_t hybbx_chess_player_color(const chess_game_t *game,
+                                       const struct hybbx_session *session)
+{
+    if (game == NULL || session == NULL) return CHESS_COLOR_NONE;
+    if (game->white_session == session) return CHESS_WHITE;
+    if (game->black_session == session) return CHESS_BLACK;
+    return CHESS_COLOR_NONE;
+}
+
+/* ── Move execution ────────────────────────────────────────── */
+
+int hybbx_chess_make_move(chess_game_t *game, const char *from,
+                          const char *to, char promote, char *err,
+                          size_t errlen)
+{
+    unsigned fr, ff, tr, tf;
+    char piece, captured;
+    int check, mate;
+    chess_color_t side, opp;
+
+    if (game == NULL || game->result != CHESS_RESULT_NONE) {
+        if (err) snprintf(err, errlen, "Game is over.");
+        return 0;
+    }
+
+    side = game->turn;
+
+    if (!parse_square(from, &fr, &ff)) {
+        if (err) snprintf(err, errlen, "Invalid square: %s", from);
+        return 0;
+    }
+    if (!parse_square(to, &tr, &tf)) {
+        if (err) snprintf(err, errlen, "Invalid square: %s", to);
+        return 0;
+    }
+
+    piece = game->board.sq[fr][ff];
+    if (piece_color(piece) != side) {
+        if (err) snprintf(err, errlen, "Not your piece.");
+        return 0;
+    }
+
+    if (!is_legal_move(&game->board, fr, ff, tr, tf, side)) {
+        if (err) snprintf(err, errlen, "Illegal move.");
+        return 0;
+    }
+
+    captured = game->board.sq[tr][tf];
+    game->board.sq[tr][tf] = piece;
+    game->board.sq[fr][ff] = CHESS_EMPTY;
+
+    /* Pawn promotion */
+    if (piece_upper(piece) == 'P') {
+        if ((side == CHESS_WHITE && tr == 7) ||
+            (side == CHESS_BLACK && tr == 0)) {
+            char pp = promote ? (char)toupper((unsigned char)promote) : 'Q';
+            game->board.sq[tr][tf] = (side == CHESS_WHITE) ? pp :
+                                      (char)tolower((unsigned char)pp);
+        }
+    }
+
+    opp = (side == CHESS_WHITE) ? CHESS_BLACK : CHESS_WHITE;
+    check = is_in_check(&game->board, opp);
+    mate = check && !has_any_legal_move(&game->board, opp);
+
+    make_san(game->last_move_san, sizeof(game->last_move_san), piece,
+             ff, tr, tf, captured != CHESS_EMPTY, check, mate, promote);
+
+    if (mate) {
+        game->result = (side == CHESS_WHITE) ? CHESS_WHITE_WINS :
+                                                CHESS_BLACK_WINS;
+    } else if (!has_any_legal_move(&game->board, opp)) {
+        game->result = CHESS_DRAW_STALEMATE;
+    }
+
+    game->turn = opp;
+    if (opp == CHESS_WHITE) game->move_number++;
+    game->tick_counter = 0;
+
+    hybbx_log_info("[chess] %s: %s %s", game->game_id,
+                   (side == CHESS_WHITE) ? game->white_name : game->black_name,
+                   game->last_move_san);
+    return 1;
+}
+
+/* ── Resign / Draw ─────────────────────────────────────────── */
+
+void hybbx_chess_resign(chess_game_t *game, struct hybbx_session *who)
+{
+    if (game == NULL || game->result != CHESS_RESULT_NONE) return;
+    if (game->white_session == who)
+        game->result = CHESS_BLACK_WINS;
+    else if (game->black_session == who)
+        game->result = CHESS_WHITE_WINS;
+}
+
+void hybbx_chess_offer_draw(chess_game_t *game, struct hybbx_session *who)
+{
+    (void)who;
+    if (game == NULL || game->result != CHESS_RESULT_NONE) return;
+    game->result = CHESS_DRAW_AGREEMENT;
+}
+
+/* ── Board rendering ───────────────────────────────────────── */
+
+void hybbx_chess_render_board(const chess_board_t *board,
+                              struct hybbx_session *session,
+                              const char *label)
+{
+    static const char *glyph = ".KQRBNPkqrbnp";
+    char line[96];
+    unsigned r, f;
+
+    if (label && label[0])
+        hybbx_session_write_line(session, label);
+
+    hybbx_session_write_line(session,
+        "  +---+---+---+---+---+---+---+---+");
+
+    for (r = 0; r < 8; r++) {
+        unsigned rank = 7 - r;
+        int n = snprintf(line, sizeof(line), "%u |", rank + 1);
+        for (f = 0; f < 8; f++) {
+            char p = board->sq[rank][f];
+            const char *ch;
+            switch (p) {
+            case 'K': ch = "K"; break; case 'Q': ch = "Q"; break;
+            case 'R': ch = "R"; break; case 'B': ch = "B"; break;
+            case 'N': ch = "N"; break; case 'P': ch = "P"; break;
+            case 'k': ch = "k"; break; case 'q': ch = "q"; break;
+            case 'r': ch = "r"; break; case 'b': ch = "b"; break;
+            case 'n': ch = "n"; break; case 'p': ch = "p"; break;
+            default:  ch = "."; break;
+            }
+            n += snprintf(line + n, sizeof(line) - (size_t)n, " %s |", ch);
+        }
+        hybbx_session_write_line(session, line);
+        hybbx_session_write_line(session,
+            "  +---+---+---+---+---+---+---+---+");
+    }
+    hybbx_session_write_line(session,
+        "    a   b   c   d   e   f   g   h");
+}
+
+void hybbx_chess_send_board(chess_game_t *game,
+                            struct hybbx_session *session)
+{
+    char label[96];
+    const char *turn_name;
+
+    if (game == NULL || session == NULL) return;
+
+    turn_name = (game->turn == CHESS_WHITE) ? game->white_name :
+                                                game->black_name;
+
+    if (game->result != CHESS_RESULT_NONE) {
+        const char *result_str;
+        switch (game->result) {
+        case CHESS_WHITE_WINS:     result_str = "1-0 White wins"; break;
+        case CHESS_BLACK_WINS:     result_str = "0-1 Black wins"; break;
+        case CHESS_DRAW_STALEMATE: result_str = "1/2-1/2 Stalemate"; break;
+        case CHESS_DRAW_AGREEMENT: result_str = "1/2-1/2 Draw"; break;
+        default:                   result_str = "Game over"; break;
+        }
+        snprintf(label, sizeof(label), "[%s] %s vs %s  %s  Move %u",
+                 game->game_id, game->white_name, game->black_name,
+                 result_str, game->move_number);
+    } else {
+        snprintf(label, sizeof(label),
+                 "[%s] %s(W) vs %s(B)  %s to move  %s  Move %u",
+                 game->game_id, game->white_name, game->black_name,
+                 turn_name,
+                 game->last_move_san[0] ? game->last_move_san : "",
+                 game->move_number);
+    }
+
+    hybbx_chess_render_board(&game->board, session, label);
+}
+
+/* ── 15-second broadcast tick ──────────────────────────────── */
+
+void hybbx_chess_tick(struct hybbx_service *service)
+{
+    unsigned i, j;
+
+    (void)service;
+
+    for (i = 0; i < g_max_games; i++) {
+        chess_game_t *g = &g_games[i];
+
+        if (!g->active) continue;
+        if (g->black_session == NULL) continue;
+
+        g->tick_counter++;
+        if (g->tick_counter < CHESS_REFRESH_SEC) continue;
+        g->tick_counter = 0;
+
+        if (g->white_session)
+            hybbx_chess_send_board(g, g->white_session);
+        if (g->black_session)
+            hybbx_chess_send_board(g, g->black_session);
+        for (j = 0; j < g->spectator_count; j++)
+            hybbx_chess_send_board(g, g->spectators[j]);
+    }
+}
diff --git a/src/core/chess_cmd.c b/src/core/chess_cmd.c
new file mode 100644
index 0000000..6ad1058
--- /dev/null
+++ b/src/core/chess_cmd.c
@@ -0,0 +1,397 @@
+/* ── Chess command handler ──────────────────────────────────── */
+
+#include "hybbx/chess.h"
+#include "hybbx/session.h"
+#include "hybbx/service.h"
+#include "hybbx/hybbx.h"
+
+#include <string.h>
+#include <strings.h>
+#include <stdio.h>
+#include <ctype.h>
+
+static int str_ieq(const char *a, const char *b)
+{
+    if (a == NULL || b == NULL) return 0;
+    while (*a != '\0' && *b != '\0') {
+        char ca = (char)(*a >= 'A' && *a <= 'Z' ? *a + 32 : *a);
+        char cb = (char)(*b >= 'A' && *b <= 'Z' ? *b + 32 : *b);
+        if (ca != cb) return 0;
+        a++; b++;
+    }
+    return *a == '\0' && *b == '\0';
+}
+
+hybbx_result_t cmd_chess(hybbx_service_t *service,
+                         hybbx_session_t *session,
+                         const hybbx_parsed_command_t *cmd)
+{
+    const char *sub;
+    chess_game_t *game;
+    char line[128];
+
+    (void)service;
+
+    if (!hybbx_session_logged_in(session)) {
+        hybbx_session_write_line(session, "Log in to play chess.");
+        return HYBBX_ERR_DENIED;
+    }
+
+    sub = (cmd->argc >= 1) ? cmd->argv[0] : "help";
+
+    /* ── /chess help ───────────────────────────────────────── */
+    if (str_ieq(sub, "help") || str_ieq(sub, "?")) {
+        hybbx_session_write_line(session, "Chess commands:");
+        hybbx_session_write_line(session,
+            "  /chess new        - Create a new game (you are White)");
+        hybbx_session_write_line(session,
+            "  /chess join       - Join an open game as Black");
+        hybbx_session_write_line(session,
+            "  /chess join G2    - Join a specific game by ID");
+        hybbx_session_write_line(session,
+            "  /chess watch      - Watch a game as spectator");
+        hybbx_session_write_line(session,
+            "  /chess watch G2   - Watch a specific game");
+        hybbx_session_write_line(session,
+            "  /chess board      - Show current board");
+        hybbx_session_write_line(session,
+            "  /chess move e2 e4 - Move piece (alias: /mv e2 e4)");
+        hybbx_session_write_line(session,
+            "  /chess resign     - Resign the game");
+        hybbx_session_write_line(session,
+            "  /chess draw       - Offer/accept draw");
+        hybbx_session_write_line(session,
+            "  /chess list       - List games with board + spectators");
+        hybbx_session_write_line(session,
+            "  /chess leave      - Stop watching");
+        hybbx_session_write_line(session,
+            "Board auto-refreshes every 15 seconds for all.");
+        return HYBBX_OK;
+    }
+
+    /* ── /chess list ───────────────────────────────────────── */
+    if (str_ieq(sub, "list") || str_ieq(sub, "ls")) {
+        unsigned found = 0;
+        unsigned i;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            game = hybbx_chess_get_game(i);
+            if (game == NULL || !game->active) continue;
+
+            /* Header: game id, players, state */
+            {
+                const char *state =
+                    (game->result != CHESS_RESULT_NONE) ? "finished" :
+                    (game->black_session == NULL) ? "waiting for Black" : "playing";
+                snprintf(line, sizeof(line),
+                         "[%s] %s(W) vs %s(B)  %s  move %u",
+                         game->game_id, game->white_name,
+                         game->black_session ? game->black_name : "...",
+                         state, game->move_number);
+            }
+            hybbx_session_write_line(session, line);
+
+            /* Board */
+            hybbx_chess_send_board(game, session);
+
+            /* Spectators */
+            if (game->spectator_count > 0) {
+                unsigned j;
+                int n = snprintf(line, sizeof(line), "  Spectators (%u): ",
+                                 game->spectator_count);
+                for (j = 0; j < game->spectator_count; j++) {
+                    const char *sname = hybbx_session_display_name(
+                                            game->spectators[j]);
+                    if (j > 0)
+                        n += snprintf(line + n, sizeof(line) - (size_t)n, ", ");
+                    n += snprintf(line + n, sizeof(line) - (size_t)n, "%s",
+                                  sname ? sname : "?");
+                }
+                hybbx_session_write_line(session, line);
+            }
+
+            hybbx_session_write_line(session, "");
+            found++;
+        }
+        if (!found)
+            hybbx_session_write_line(session, "  No active games.");
+        return HYBBX_OK;
+    }
+
+    /* ── /chess new ────────────────────────────────────────── */
+    if (str_ieq(sub, "new") || str_ieq(sub, "create")) {
+        unsigned i;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            game = hybbx_chess_get_game(i);
+            if (game && game->active &&
+                hybbx_chess_is_player(game, session)) {
+                hybbx_session_write_line(session,
+                    "You are already in a game. /chess resign first.");
+                return HYBBX_ERR_DENIED;
+            }
+        }
+        game = hybbx_chess_create_game(session,
+                                       hybbx_session_username(session));
+        if (game == NULL) {
+            hybbx_session_write_line(session, "No free game slots.");
+            return HYBBX_ERR_DENIED;
+        }
+        snprintf(line, sizeof(line), "Game %s created. You are White.",
+                 game->game_id);
+        hybbx_session_write_line(session, line);
+        hybbx_session_write_line(session,
+            "Waiting for Black to /chess join...");
+        hybbx_chess_send_board(game, session);
+        return HYBBX_OK;
+    }
+
+    /* ── /chess join [id] ──────────────────────────────────── */
+    if (str_ieq(sub, "join")) {
+        const char *id = (cmd->argc >= 2) ? cmd->argv[1] : NULL;
+        unsigned i;
+
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            game = hybbx_chess_get_game(i);
+            if (game && game->active &&
+                hybbx_chess_is_player(game, session)) {
+                hybbx_session_write_line(session,
+                    "You are already in a game. /chess resign first.");
+                return HYBBX_ERR_DENIED;
+            }
+        }
+
+        if (id) {
+            game = hybbx_chess_find_game_by_id(id);
+            if (game == NULL || !game->active) {
+                hybbx_session_write_line(session, "Game not found.");
+                return HYBBX_ERR_NOT_FOUND;
+            }
+            if (game->black_session != NULL) {
+                hybbx_session_write_line(session, "Game is full.");
+                return HYBBX_ERR_DENIED;
+            }
+        } else {
+            game = hybbx_chess_find_open_game();
+            if (game == NULL) {
+                hybbx_session_write_line(session,
+                    "No open games. /chess new to create one.");
+                return HYBBX_ERR_NOT_FOUND;
+            }
+        }
+
+        hybbx_chess_join_game(game, session,
+                              hybbx_session_username(session));
+        snprintf(line, sizeof(line), "Joined %s as Black. Game on!",
+                 game->game_id);
+        hybbx_session_write_line(session, line);
+        hybbx_chess_send_board(game, game->white_session);
+        hybbx_chess_send_board(game, session);
+        return HYBBX_OK;
+    }
+
+    /* ── /chess watch [id] ─────────────────────────────────── */
+    if (str_ieq(sub, "watch") || str_ieq(sub, "spectate")) {
+        const char *id = (cmd->argc >= 2) ? cmd->argv[1] : NULL;
+        unsigned i;
+
+        if (id) {
+            game = hybbx_chess_find_game_by_id(id);
+        } else {
+            game = NULL;
+            for (i = 0; i < hybbx_chess_max_games(); i++) {
+                chess_game_t *g = hybbx_chess_get_game(i);
+                if (g && g->active && g->black_session != NULL) {
+                    game = g;
+                    break;
+                }
+            }
+        }
+        if (game == NULL || !game->active) {
+            hybbx_session_write_line(session, "No game to watch.");
+            return HYBBX_ERR_NOT_FOUND;
+        }
+        if (!hybbx_chess_add_spectator(game, session)) {
+            hybbx_session_write_line(session, "Spectator list full.");
+            return HYBBX_ERR_DENIED;
+        }
+        snprintf(line, sizeof(line),
+                 "Watching %s. Board refreshes every %ds.",
+                 game->game_id, CHESS_REFRESH_SEC);
+        hybbx_session_write_line(session, line);
+        hybbx_chess_send_board(game, session);
+        return HYBBX_OK;
+    }
+
+    /* ── /chess leave ──────────────────────────────────────── */
+    if (str_ieq(sub, "leave") || str_ieq(sub, "unwatch")) {
+        unsigned i;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            game = hybbx_chess_get_game(i);
+            if (game && game->active &&
+                hybbx_chess_is_spectator(game, session)) {
+                hybbx_chess_remove_spectator(game, session);
+                hybbx_session_write_line(session, "Stopped watching.");
+                return HYBBX_OK;
+            }
+        }
+        hybbx_session_write_line(session,
+            "You are not watching any game.");
+        return HYBBX_ERR_NOT_FOUND;
+    }
+
+    /* ── /chess board ──────────────────────────────────────── */
+    if (str_ieq(sub, "board") || str_ieq(sub, "show")) {
+        unsigned i;
+        game = NULL;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            chess_game_t *g = hybbx_chess_get_game(i);
+            if (g && g->active &&
+                (hybbx_chess_is_player(g, session) ||
+                 hybbx_chess_is_spectator(g, session))) {
+                game = g;
+                break;
+            }
+        }
+        if (game == NULL) {
+            hybbx_session_write_line(session,
+                "Not in a game. /chess new, join, or watch.");
+            return HYBBX_ERR_NOT_FOUND;
+        }
+        hybbx_chess_send_board(game, session);
+        return HYBBX_OK;
+    }
+
+    /* ── /chess move e2 e4 ─────────────────────────────────── */
+    if (str_ieq(sub, "move") || str_ieq(sub, "mv") || str_ieq(sub, "m")) {
+        const char *from, *to;
+        char err[64];
+        unsigned i;
+
+        if (cmd->argc < 3) {
+            hybbx_session_write_line(session,
+                "Usage: /chess move e2 e4");
+            return HYBBX_ERR_INVALID;
+        }
+        from = cmd->argv[1];
+        to   = cmd->argv[2];
+
+        game = NULL;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            chess_game_t *g = hybbx_chess_get_game(i);
+            if (g && g->active && g->result == CHESS_RESULT_NONE &&
+                hybbx_chess_is_player(g, session)) {
+                chess_color_t color = hybbx_chess_player_color(g, session);
+                if (color == g->turn) {
+                    game = g;
+                    break;
+                }
+            }
+        }
+        if (game == NULL) {
+            hybbx_session_write_line(session,
+                "Not your turn or no active game.");
+            return HYBBX_ERR_DENIED;
+        }
+
+        if (!hybbx_chess_make_move(game, from, to, 0, err, sizeof(err))) {
+            snprintf(line, sizeof(line), "Illegal: %s", err);
+            hybbx_session_write_line(session, line);
+            return HYBBX_ERR_INVALID;
+        }
+
+        /* Broadcast to all */
+        if (game->white_session)
+            hybbx_chess_send_board(game, game->white_session);
+        if (game->black_session)
+            hybbx_chess_send_board(game, game->black_session);
+        {
+            unsigned j;
+            for (j = 0; j < game->spectator_count; j++)
+                hybbx_chess_send_board(game, game->spectators[j]);
+        }
+
+        if (game->result != CHESS_RESULT_NONE) {
+            const char *res;
+            unsigned j;
+            switch (game->result) {
+            case CHESS_WHITE_WINS:     res = "White wins!"; break;
+            case CHESS_BLACK_WINS:     res = "Black wins!"; break;
+            case CHESS_DRAW_STALEMATE: res = "Stalemate!"; break;
+            case CHESS_DRAW_AGREEMENT: res = "Draw!"; break;
+            default:                   res = "Game over."; break;
+            }
+            snprintf(line, sizeof(line), "[%s] %s", game->game_id, res);
+            if (game->white_session)
+                hybbx_session_write_line(game->white_session, line);
+            if (game->black_session)
+                hybbx_session_write_line(game->black_session, line);
+            for (j = 0; j < game->spectator_count; j++)
+                hybbx_session_write_line(game->spectators[j], line);
+        }
+
+        return HYBBX_OK;
+    }
+
+    /* ── /chess resign ─────────────────────────────────────── */
+    if (str_ieq(sub, "resign")) {
+        unsigned i;
+        game = NULL;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            chess_game_t *g = hybbx_chess_get_game(i);
+            if (g && g->active && hybbx_chess_is_player(g, session)) {
+                game = g;
+                break;
+            }
+        }
+        if (game == NULL) {
+            hybbx_session_write_line(session, "You are not in a game.");
+            return HYBBX_ERR_NOT_FOUND;
+        }
+        hybbx_chess_resign(game, session);
+        snprintf(line, sizeof(line), "[%s] %s resigned.",
+                 game->game_id, hybbx_session_username(session));
+        if (game->white_session)
+            hybbx_session_write_line(game->white_session, line);
+        if (game->black_session)
+            hybbx_session_write_line(game->black_session, line);
+        {
+            unsigned j;
+            for (j = 0; j < game->spectator_count; j++)
+                hybbx_session_write_line(game->spectators[j], line);
+        }
+        return HYBBX_OK;
+    }
+
+    /* ── /chess draw ───────────────────────────────────────── */
+    if (str_ieq(sub, "draw")) {
+        unsigned i;
+        game = NULL;
+        for (i = 0; i < hybbx_chess_max_games(); i++) {
+            chess_game_t *g = hybbx_chess_get_game(i);
+            if (g && g->active && hybbx_chess_is_player(g, session)) {
+                game = g;
+                break;
+            }
+        }
+        if (game == NULL) {
+            hybbx_session_write_line(session, "You are not in a game.");
+            return HYBBX_ERR_NOT_FOUND;
+        }
+        hybbx_chess_offer_draw(game, session);
+        snprintf(line, sizeof(line), "[%s] Draw agreed.",
+                 game->game_id);
+        if (game->white_session)
+            hybbx_session_write_line(game->white_session, line);
+        if (game->black_session)
+            hybbx_session_write_line(game->black_session, line);
+        {
+            unsigned j;
+            for (j = 0; j < game->spectator_count; j++)
+                hybbx_session_write_line(game->spectators[j], line);
+        }
+        return HYBBX_OK;
+    }
+
+    hybbx_session_write_line(session,
+        "Unknown chess command. /chess help for list.");
+    return HYBBX_ERR_NOT_FOUND;
+}
diff --git a/src/core/command.c b/src/core/command.c
index b60ee35..8cd4e5c 100644
--- a/src/core/command.c
+++ b/src/core/command.c
@@ -18,6 +18,7 @@
 #include "hybbx/password.h"
 #include "hybbx/traffic.h"
 #include "hybbx/monitor.h"
+#include "hybbx/chess.h"
 #include "hybbx/util.h"
 
 #include <stdio.h>
@@ -2311,6 +2312,11 @@ hybbx_result_t hybbx_command_dispatch(hybbx_service_t *service,
         return cmd_monitor(service, session, cmd);
     }
 
+    if (str_ieq(cmd->verb, "chess") || str_ieq(cmd->verb, "play")) {
+        return cmd_chess(service, session, cmd);
+    }
+
+
     if (str_ieq(cmd->verb, "users")) {
         return cmd_users(service, session);
     }
diff --git a/src/core/commands_registry.c b/src/core/commands_registry.c
index 6f63178..6b0be63 100644
--- a/src/core/commands_registry.c
+++ b/src/core/commands_registry.c
@@ -1312,15 +1312,15 @@ void hybbx_commands_registry_show_menu(hybbx_session_t *session)
     }
 
     /*
-     * Allow-list grants are not Sysop — their menu layout has no Sysop area.
-     * Append filtered Sysop area so /monitor is visible when granted.
+     * Allow-list grants are not Sysop - their menu layout has no Monitor area.
+     * Append filtered Monitor area so /monitor is visible when granted.
      */
     if (hybbx_monitor_session_may_use(session) &&
         !hybbx_user_level_is_sysop(level)) {
-        const menu_area_t *sysop = area_find("Sysop");
+        const menu_area_t *monitor = area_find("Monitor");
 
-        if (sysop != NULL) {
-            render_area(session, sysop, level, 1);
+        if (monitor != NULL) {
+            render_area(session, monitor, level, 1);
         }
     }
 }
@@ -1335,11 +1335,11 @@ void hybbx_commands_registry_show_index(hybbx_session_t *session)
 
     level = hybbx_session_user_level(session);
     hybbx_session_write_line(session, g_registry.index_header);
-    /* Filter by access — Sysop cmds (incl. /monitor) only for Sysop + grants. */
+    /* No access filter - /index lists ALL commands for every user level. */
     render_area_labels(session,
                        (const char (*)[16])g_registry.index_labels,
                        g_registry.index_label_count,
-                       level, 1);
+                       level, 0);
 }
 
 void hybbx_commands_registry_show_aliases(hybbx_session_t *session)
diff --git a/src/core/service.c b/src/core/service.c
index a8bd402..6cf2b16 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -26,6 +26,8 @@ void hybbx_mains_proxy_plugin_tick(void);
 #include "hybbx/instance.h"
 #include "hybbx/log.h"
 #include "hybbx/monitor.h"
+#include "hybbx/chess.h"
+#include <errno.h>
 #include "hybbx/security.h"
 #include "hybbx/security_ban.h"
 #include "hybbx/util.h"
@@ -166,6 +168,7 @@ void hybbx_service_destroy(hybbx_service_t *service)
     }
 
     hybbx_monitor_shutdown();
+    hybbx_chess_init();
     hybbx_log_shutdown();
     hybbx_security_log_shutdown();
     hybbx_security_ban_shutdown();
@@ -978,10 +981,21 @@ hybbx_result_t hybbx_service_run(hybbx_service_t *service)
         Sleep(1000);
 #else
         static unsigned prune_tick;
+        static unsigned health_tick;
 
         sleep(1);
+
+        /* Periodic health log — every 300s (5 min) */
+        health_tick++;
+        if (health_tick >= 300u) {
+            health_tick = 0;
+            hybbx_log_info("[service] health: running=%d transports=%u sessions_active (tick)",
+                           svc->running, svc->transport_count);
+        }
+
         hybbx_security_ban_tick();
         hybbx_monitor_tick(service);
+        hybbx_chess_tick(service);
         hybbx_broadcast_ax25_tick(service);
 #ifdef HYBBX_HAVE_PLUGIN_MAINS_PROXY
         hybbx_mains_proxy_plugin_tick();
@@ -1209,6 +1223,7 @@ hybbx_result_t hybbx_service_apply_config(hybbx_service_t *service,
     hybbx_log_config_apply(config);
     hybbx_security_log_config_apply(config);
     hybbx_monitor_config_apply(config);
+    hybbx_chess_config_apply(config);
     hybbx_security_ban_config_apply(config);
     service_apply_texts(svc, config);
     hybbx_chat_config_apply(&svc->chat, config);