Source excerpts

typedef struct {
    uint32_t       id;                           /* unique event ID (starts at 1) */
    uint32_t       node_hash;                    /* node identity hash            */
    causal_time_t  time;                         /* when it happened              */
    causal_type_t  type;                         /* event category                */
    char           subsystem[16];                /* e.g. "sched", "fs", "tcp"     */
    char           desc[CAUSAL_DESC_LEN];        /* human-readable description    */
    uint8_t        payload[CAUSAL_PAYLOAD_LEN];  /* optional structured data      */
    uint32_t       payload_len;
    uint8_t        payload_hash[32];             /* cached when payload bytes are unavailable */
    bool           payload_hash_valid;
    uint16_t       schema_id;
    uint8_t        schema_version;
    uint32_t       parents[CAUSAL_MAX_PARENTS];  /* IDs of causal parent events   */
    uint8_t        num_parents;
    uint16_t       child_count;                  /* updated as children are added */
} causal_event_t;

static causal_event_t events[CAUSAL_MAX_EVENTS];
static uint32_t       event_count;          /* events currently in ring   */
static uint32_t       next_id = 1;          /* monotonically increasing   */
static uint64_t       lamport_clock;        /* Lamport logical clock      */
static uint32_t       node_hash;            /* mesh node identity (0=local) */
#define CAUSAL_HYDRATE_CACHE 512

static causal_event_t hydrated[CAUSAL_HYDRATE_CACHE]; /* read-through journal cache */
static uint32_t       hydrated_next;

static void seg_filename(uint32_t seg_num, char *buf, int bufsz)
{
    ksnprintf(buf, bufsz, "%s/seg-%08u.jnl", CJOURNAL_DIR, seg_num);
}

static void seg_hash_filename(uint32_t seg_num, char *buf, int bufsz)
{
    ksnprintf(buf, bufsz, "%s/seg-%08u.hsh", CJOURNAL_DIR, seg_num);
}

static void seg_root_filename(uint32_t seg_num, char *buf, int bufsz)
{
    ksnprintf(buf, bufsz, "%s/seg-%08u.ert", CJOURNAL_DIR, seg_num);
}

int replay_at(uint32_t tick, replay_snapshot_t *snap)
{
    if (!snap) return -1;

    /* Zero the snapshot */
    uint8_t *p = (uint8_t *)snap;
    for (size_t i = 0; i < sizeof(*snap); i++)
        p[i] = 0;

    snap->tick = tick;

    /* Walk the live causal ring from its oldest retained event up to the
     * newest, including every event whose wall_ticks is within [0, tick].
     * We filter rather than break: event ids are NOT strictly tick-ordered
     * (a journal restore re-emits historical events with fresh low ids but
     * their original large wall_ticks), so an early break could drop the live
     * session.  Walking the whole ring window (<= 16384 events) is cheap and,
     * unlike the old 256-event sample, yields accurate counts and the true
     * newest events at the requested tick. */
    uint32_t newest = causal_total_events();
    uint32_t oldest = causal_oldest_event_id();
    uint32_t count = 0;

static int api_causal_state_at(char *buf, int max, uint32_t tick) {
    struct sys_replaysnap snap;
    if (replay_at_tick(tick, &snap) != 0)
        return buf_append(buf, 0, max, "{\"error\":\"replay failed\"}");

    int p = 0;
    p = buf_append(buf, p, max, "{\"tick\":");
    p = buf_uint(buf, p, max, snap.tick);
    p = buf_append(buf, p, max, ",\"total_events\":");
    p = buf_uint(buf, p, max, snap.total_events);
    p = buf_append(buf, p, max, ",\"tasks\":{\"alive\":");
    p = buf_uint(buf, p, max, snap.tasks_alive);

/* SlOS — Causal Inspector: time-travel scrubber

   Scrub through the kernel's causal timeline and watch system state get
   reconstructed at any past tick via the replay engine (SYS_REPLAY_AT).

     scrub                interactive full-screen TUI (arrow keys scrub time;
                          'i' inspects an event and walks the causal DAG)
     scrub <tick>         print one reconstructed frame at <tick> and exit
     scrub event <id|last>  print one event's causal DAG focus and exit
     scrub whatif <id|last> print the counterfactual impact of dropping an event
     scrub diff <a> <b>     print what changed between tick a and tick b
     scrub json [tick]      print the reconstructed state at <tick> (or now) as JSON
*/

int timeline_create(const char *name, const char *app)
{
    if (!name || !app) return -1;

    /* Check for duplicate */
    for (int i = 0; i < TIMELINE_MAX; i++) {
        if (timelines[i].active && strcmp(timelines[i].name, name) == 0)
            return -1;
    }

    /* Find free slot */
    for (int i = 0; i < TIMELINE_MAX; i++) {
        if (!timelines[i].active) {
            memset(&timelines[i], 0, sizeof(timeline_t));
            timeline_cache_reset(i);
            strncpy(timelines[i].name, name, TIMELINE_NAME_LEN - 1);
            strncpy(timelines[i].app, app, 15);
            timelines[i].active = true;
            timelines[i].create_tick = system_ticks;

#define TELNET_PORT      23
#define NOISE_SHELL_PORT 5200
#define NAWS 31      /* Negotiate About Window Size */

case SYS_TERM_GETKEY:
    regs->REG_AX = (uint32_t)term_getkey(cur);
    break;

case SYS_CON_GETSIZE:
    {
        int rows = 25, cols = 80;
        task_get_term_size(task_current(), &rows, &cols);
        regs->REG_AX = (rows << 16) | cols;
    }
    break;

void console_clear(void) {
    if (remote_console_task())
        remote_ansi("\x1b[2J\x1b[H");
}

void console_set_cursor(int row, int col) {
    cursor_y = row;
    cursor_x = col;
    if (remote_console_task())
        remote_ansi("\x1b[%d;%dH", row + 1, col + 1);
    update_cursor();
}