feat: TCP connect fallback for ping, flag high latency vs. ping

- If a peer filters ICMP, measure the TCP connect time to its peer port
  instead; such values are marked with a trailing "t"
- Show ⚡ between Latency and Ping when stellar-core's latency exceeds
  the ping/TCP RTT by more than LATENCY_PING_RATIO (3), hinting at a
  VPN exit / relay in front of the actual node
- Legend below the peer table, only for markers actually shown

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -14,11 +14,29 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ./pi-stat -g / --geo             # With geolocation (implies -p)
 ./pi-stat -s / --show-ip         # Show IP column (hidden by default)
 ./pi-stat -x / --extended        # Show full RX/TX/RX-rate/TX-rate columns (default: ratio only)
-./pi-stat -i [SEC] / --interactive [SEC]  # Interactive auto-refresh (default: 10s)
+./pi-stat -i [SEC] / --interactive [SEC]  # Interactive auto-refresh (default: 5s, configurable)
 ```
 
 No build step. Requires `pip install docker` and a running Docker daemon. Runs on Linux, WSL2, and Windows.
 
+## Configuration
+
+Optional JSON config file, first match wins: `$PI_STAT_CONFIG` → `~/.config/pi-stat/config.json` → `<script dir>/pi-stat.json` (see `pi-stat.json`, shipped with the repo). Loaded by `load_config()`; missing, unreadable or non-object files fall back to defaults with a warning on stderr.
+
+| Key | Default | Meaning |
+| --- | --- | --- |
+| `refresh_interval` | `5` | Interactive auto-refresh interval in seconds (clamped to >= 1) |
+
+Precedence for the refresh interval: `-i SEC` on the command line > config file > `DEFAULT_REFRESH` (5).
+
+Standard JSON has no comment syntax; document settings with a `_comment` key instead (any key not read by `config_refresh()` is ignored), e.g.:
+```json
+{
+  "_comment": "refresh_interval in seconds, min. 1 (default: 5)",
+  "refresh_interval": 5
+}
+```
+
 ## Architecture
 
 Single self-contained script (`pi-stat`). Logic is split into helper functions and a `run_cycle()` function that collects data and renders one full screen, called either once (normal mode) or in a loop (interactive mode).
@@ -27,10 +45,11 @@ Single self-contained script (`pi-stat`). Logic is split into helper functions a
 
 - **Docker SDK** — container CPU/RAM stats; all commands run inside the auto-detected container (`mainnet` → `testnet2` → `testnet`, first running one) via `exec_run`
 - **Stellar Core HTTP API** — `exec_json()` runs `stellar-core http-command <cmd>` inside the container
-- **Horizon API** — `http://localhost:31401`
+- **Horizon API** — `curl http://127.0.0.1:8000/` run inside the container via `exec_json()`, not via the host port `31401` (host→bridge forwarding can hang until timeout if Docker's host firewall rules are broken)
 - **PostgreSQL** — `psql` inside the container; used for peer DB counts and pubkey→IP mapping
 - **ZFS CLI** — `zpool`/`zfs` commands on the host for disk health (`z01pool`); if `zpool` is not found (`HAS_ZFS = False`), falls back to `shutil.disk_usage()` — works on Linux without ZFS, WSL2, and Windows
 - **ip-api.com** — batch geolocation (Country, City), cached in `_geo_cache`; only fetched with `-g`
+- **System `ping` / TCP connect** — per peer from the host (`ping_batch()`, parallel, private IPs skipped): one ICMP ping (1 s timeout); if the peer filters ICMP, falls back to a TCP connect on the peer port from its address (1 s timeout). Shown as `Ping` next to stellar-core's `Latency` in the `-p`/`-g` table; TCP values are marked with a trailing `t` (legend printed below the table), `—` if neither answers
 
 ### Output sections (in order)
 
@@ -49,11 +68,17 @@ Single self-contained script (`pi-stat`). Logic is split into helper functions a
 
 Outbound peers are numbered in the table. Full node IDs are fetched via `peers?fullkeys=true` for the `droppeer` API call.
 
+The refresh deadline is anchored to the start of the cycle (`cycle_start`), not its end, so the update's own execution time doesn't stack on top of `refresh_interval`. Execution time is measured and a warning is printed (into the same buffered screen) when a cycle takes >= `REFRESH_WARN_RATIO` (80%) of the interval, or exceeds it outright.
+
 ### Key patterns
 
 - **Graceful degradation** — every external call is wrapped in try-except; missing data renders as `—`
 - **Dynamic column widths** — all table columns sized at runtime from actual data length
 - **NAT detection** — inbound peers with private IPs are replaced with their DB-stored public IP (`db_peer_addr` from PostgreSQL)
 - **Validator matching** — `load_validators()` parses `stellar-core.cfg` and indexes by IP, name, and public key; matched peers show a truncated key + `(Vn)` label
+- **Ping vs. Latency** — `Latency` is stellar-core's round trip to the peer *process*, `Ping` is ICMP to the peer's IP; a low ping with high latency hints at a VPN exit / relay in front of the actual node. Peers with `Latency > LATENCY_PING_RATIO (3) × Ping` get a `⚡` between the two columns (2-column cell, since `⚡` is double-width in terminals); a legend line is printed below the table only when a `⚡` or `t` marker is present
 - **Geo caching** — `_geo_cache` is a module-level dict; `geo_batch()` only fetches IPs not already cached
 - **Flag parsing** — manual `sys.argv` parsing; `-g` implies `-p`; `-i` accepts an optional next argument as the refresh interval
+- **Config precedence** — `config_refresh()` reads the config value; an explicit `-i SEC` argument overrides it
+- **Cycle timing** — `interactive_loop()` measures cycle duration and warns via `warn()` when it nears or exceeds `refresh_interval`, so a slow update doesn't silently push out the actual refresh cadence
+- **Persistent cbreak** — the tty is switched to cbreak once for the whole session (not reset to canonical between cycles); doing it per-cycle would flush unread input on the mode switch and leave the terminal line-buffered during `run_cycle()`, silently dropping keypresses (e.g. `q`) made while a cycle overruns `refresh_interval`

pi-stat

@@ -18,6 +18,7 @@ import socket
 import subprocess
 import sys
 import time
+from concurrent.futures import ThreadPoolExecutor
 from datetime import datetime, timezone
 from urllib.request import urlopen, Request
 from urllib.error import URLError
@@ -38,8 +39,16 @@ except ImportError:
 # --- Configuration ---
 HAS_ZFS              = shutil.which("zpool") is not None
 CANDIDATE_CONTAINERS = ["mainnet", "testnet2", "testnet"]
-HORIZON_URL          = "http://localhost:31401"
+HORIZON_URL          = "http://127.0.0.1:8000"  # queried from inside the container, not via the host port
 CFG_PATH             = os.path.join(os.path.dirname(os.path.realpath(__file__)), "stellar-core.cfg")
+DEFAULT_REFRESH      = 5
+REFRESH_WARN_RATIO   = 0.8  # warn if a cycle takes >= 80% of the refresh interval
+LATENCY_PING_RATIO   = 3    # mark peers with ⚡ when core latency > 3× ping/TCP RTT
+CONFIG_PATHS         = [
+    os.environ.get("PI_STAT_CONFIG"),
+    os.path.join(os.path.expanduser("~"), ".config", "pi-stat", "config.json"),
+    os.path.join(os.path.dirname(os.path.realpath(__file__)), "pi-stat.json"),
+]
 
 # --- Colors / Icons ---
 GREEN  = "\033[0;32m"
@@ -144,6 +153,110 @@ def geo_str(ip):
         return ", ".join(p for p in geo if p)
     return ""
 
+HAS_PING = shutil.which("ping") is not None
+_PING_RE = re.compile(r"[=<]\s*([\d.,]+)\s*ms", re.IGNORECASE)
+
+def ping_rtt(ip, timeout_s=1):
+    """Single ICMP ping via the system 'ping'. Returns RTT in ms, or None (no reply / filtered)."""
+    if os.name == "nt":
+        cmd = ["ping", "-n", "1", "-w", str(timeout_s * 1000), ip]
+    else:
+        cmd = ["ping", "-c", "1", "-W", str(timeout_s), "-n", ip]
+    try:
+        r = subprocess.run(cmd, capture_output=True, text=True, timeout=timeout_s + 2,
+                           env={**os.environ, "LC_ALL": "C"})
+    except Exception:
+        return None
+    if r.returncode != 0:
+        return None
+    # Linux: "time=37.5 ms", Windows: "time=37ms" / "Zeit<1ms"
+    for line in r.stdout.splitlines():
+        if "ttl" in line.lower():
+            mt = _PING_RE.search(line)
+            if mt:
+                try:
+                    return float(mt.group(1).replace(",", "."))
+                except ValueError:
+                    pass
+    return None
+
+def tcp_rtt(ip, port, timeout_s=1):
+    """TCP connect time to ip:port in ms (≈ 1 RTT: SYN → SYN/ACK), or None if not connectable."""
+    t = time.perf_counter()
+    try:
+        with socket.create_connection((ip, port), timeout=timeout_s):
+            return (time.perf_counter() - t) * 1000
+    except OSError:
+        return None
+
+def probe_rtt(ip, port):
+    """ICMP ping first; if the peer filters ICMP, fall back to a TCP connect on its peer port.
+    Returns (rtt_ms, "icmp" | "tcp") or (None, None)."""
+    if HAS_PING:
+        v = ping_rtt(ip)
+        if v is not None:
+            return v, "icmp"
+    if port:
+        v = tcp_rtt(ip, port)
+        if v is not None:
+            return v, "tcp"
+    return None, None
+
+def ping_batch(addrs):
+    """Probe all public peer addresses ("ip:port") in parallel.
+    Returns {ip: (rtt_ms, kind)}; private/invalid IPs are skipped."""
+    targets = {}
+    for addr in addrs:
+        ip, _, port = addr.rpartition(":")
+        try:
+            if ipaddress.ip_address(ip).is_private:
+                continue
+        except ValueError:
+            continue
+        targets[ip] = int(port) if port.isdigit() else None
+    if not targets:
+        return {}
+    with ThreadPoolExecutor(max_workers=min(32, len(targets))) as ex:
+        return dict(zip(targets, ex.map(lambda t: probe_rtt(*t), targets.items())))
+
+def fmt_ms(v):
+    """Format a millisecond value: one decimal below 10 ms, integer above."""
+    if v is None:
+        return "—"
+    return f"{v:.1f}ms" if v < 10 else f"{v:.0f}ms"
+
+def fmt_ping(res):
+    """Ping cell: ICMP value plain, TCP-connect value marked with a trailing 't'."""
+    v, kind = res if res else (None, None)
+    return f"{fmt_ms(v)} {'t' if kind == 'tcp' else ' '}"
+
+def load_config():
+    """Read the first existing config file (JSON object). Returns {} if none is usable."""
+    for path in CONFIG_PATHS:
+        if not path or not os.path.isfile(path):
+            continue
+        try:
+            with open(path, "r", encoding="utf-8") as fh:
+                data = json.load(fh)
+            if isinstance(data, dict):
+                return data
+            print(f"WARN: Config {path}: kein JSON-Objekt – wird ignoriert", file=sys.stderr)
+        except Exception as e:
+            print(f"WARN: Config {path} nicht lesbar: {e}", file=sys.stderr)
+        return {}
+    return {}
+
+
+def config_refresh(cfg):
+    """refresh_interval from config, clamped to >= 1 s; falls back to DEFAULT_REFRESH."""
+    val = cfg.get("refresh_interval", DEFAULT_REFRESH)
+    try:
+        return max(1, int(val))
+    except (TypeError, ValueError):
+        print(f"WARN: refresh_interval '{val}' ungültig – benutze {DEFAULT_REFRESH}s", file=sys.stderr)
+        return DEFAULT_REFRESH
+
+
 def load_validators(cfg_path):
     """Parse [[VALIDATORS]] sections, returning {ip_or_name: (index, public_key)}."""
     if not os.path.exists(cfg_path):
@@ -228,12 +341,12 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
         if raw:
             core_info = raw.get("info")
 
+    # Query Horizon via curl inside the container: independent of the host's
+    # port forwarding (31401), which can hang until timeout if Docker's
+    # firewall rules on the host are broken.
     hz_data = None
-    try:
-        with urlopen(HORIZON_URL + "/", timeout=5) as resp:
-            hz_data = json.loads(resp.read())
-    except Exception:
-        pass
+    if container:
+        hz_data = exec_json(container, ["curl", "-s", "-m", "5", HORIZON_URL + "/"])
 
     # =============================================================
     # 1. CONTAINER STATUS
@@ -339,23 +452,36 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
     hdr("🌅 API Status (Horizon)")
 
     if hz_data is None:
-        err(f"Horizon API not reachable ({HORIZON_URL})")
+        err(f"Horizon API not reachable ({HORIZON_URL} in container '{container_name}')")
     else:
         core_blk  = hz_data.get("core_latest_ledger",    0)
         hist_blk  = hz_data.get("history_latest_ledger", 0)
+        elder_blk = hz_data.get("history_elder_ledger",  0)
         ings_blk  = hz_data.get("ingest_latest_ledger",  0)
-        lag       = core_blk - ings_blk
         closed_at = hz_data.get("history_latest_ledger_closed_at", "?")
 
-        if lag <= 2:
+        # Reference ledger for the ingest lag: stellar-core's own ledger if we
+        # have it, otherwise what Horizon reports for core. core_latest_ledger
+        # is 0 when Horizon has lost its connection to stellar-core; computing
+        # the lag against 0 would give a negative value and a false "Synced".
+        ref_blk = block if core_info is not None else core_blk
+        lag     = (ref_blk - ings_blk) if ref_blk else None
+
+        if not core_blk:
+            err("Status: Horizon has no connection to stellar-core (core_latest_ledger = 0)")
+            if lag is not None and lag > 2:
+                warn(f"Ingest {lag} ledger behind core")
+        elif lag <= 2:
             ok(f"Status: Synced (Ingest lag: {lag} ledger)")
         else:
             warn(f"Status: Lagging (Ingest {lag} ledger behind core)")
         core_diff = (block - core_blk) if (core_info is not None and core_blk) else None
         core_diff_str = f"  (Δ {core_diff:+d} vs Core)" if core_diff is not None else ""
-        print(f"     Core Latest Ledger:   {core_blk}{core_diff_str}")
+        core_blk_str  = str(core_blk) if core_blk else "— (not connected)"
+        print(f"     Core Latest Ledger:   {core_blk_str}{core_diff_str}")
         print(f"     Ingest Latest Ledger: {ings_blk}  (last closed: {closed_at})")
-        print(f"     History Oldest:       {hist_blk}")
+        print(f"     History Latest:       {hist_blk}")
+        print(f"     History Oldest:       {elder_blk}")
 
     # =============================================================
     # 5. NODE METRICS (stellar-core)
@@ -502,6 +628,12 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
                     _all_ips.append(node_ip_str)
                 geo_batch([ip for ip in _all_ips if ip])
 
+            # --- Ping from this host to each peer's known IP ---
+            # Compared with stellar-core's "Latency", a low ping but high
+            # latency hints at a VPN exit / relay in front of the actual node.
+            # ICMP first, TCP connect to the peer port as fallback (marked 't').
+            ping_ms = ping_batch([p.get("address", "") for p in inbound + outbound])
+
             def _is_private(ip):
                 try:
                     return ipaddress.ip_address(ip).is_private
@@ -596,10 +728,12 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
                 ratio_total = max(ratio_total, len("RX/TX"))
                 _traffic_hdr  = f"  {'RX/TX':>{ratio_total}}"
                 _traffic_node = f"  {fmt_ratio_cell(None, ratio_l_w, ratio_r_w):>{ratio_total}}"
-            HDR      = f"  {hdr_num_prefix}{'NodeID':<{col_w}}  {'Version':<{ver_w}}{_ip_hdr_part}{_geo_hdr_part}  {'Latency':>8}  {'Uptime':<8}{_traffic_hdr}  Flow"
-            NODE_ROW = f"  {node_row_prefix}{node_id_str:<{col_w}}  {node_ver_str:<{ver_w}}{_ip_node_part}{_geo_node_part}  {'—':>8}  {node_up_str:<8}{_traffic_node}  {node_flow_str}"
+            HDR      = f"  {hdr_num_prefix}{'NodeID':<{col_w}}  {'Version':<{ver_w}}{_ip_hdr_part}{_geo_hdr_part}  {'Latency':>8} {'':2} {'Ping':>9}  {'Uptime':<8}{_traffic_hdr}  Flow"
+            NODE_ROW = f"  {node_row_prefix}{node_id_str:<{col_w}}  {node_ver_str:<{ver_w}}{_ip_node_part}{_geo_node_part}  {'—':>8} {'':2} {fmt_ping(None):>9}  {node_up_str:<8}{_traffic_node}  {node_flow_str}"
             SEP      = "  " + "─" * (len(HDR) - 2)
 
+            lat_flagged = []  # peers marked ⚡ (for the legend)
+
             def show(peers, is_out):
                 for p in sorted(peers, key=lambda p: p.get("elapsed", 0), reverse=True):
                     raw_addr = p.get("address", "?").rsplit(":", 1)[0]
@@ -615,6 +749,16 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
                     ver   = fmt_version(p.get("ver", ""))
                     lat   = p.get("latency", "?")
                     lat_s = "n/a" if lat == 86400000 else f"{lat}ms"
+                    ping_res = ping_ms.get(raw_addr)
+                    ping_s = fmt_ping(ping_res)
+                    # ⚡ when stellar-core's latency exceeds the network RTT by more than
+                    # LATENCY_PING_RATIO (possible VPN exit / relay in front of the node).
+                    # "⚡" is 2 columns wide in the terminal, so the blank is 2 spaces.
+                    rtt = ping_res[0] if ping_res else None
+                    lat_flag = ("⚡" if isinstance(lat, (int, float)) and lat != 86400000
+                                and rtt and lat > LATENCY_PING_RATIO * rtt else "  ")
+                    if lat_flag == "⚡":
+                        lat_flagged.append(pid)
                     up    = fmt_up(p.get("elapsed", 0))
                     rx      = p.get("byte_read",  0) or 0
                     tx      = p.get("byte_write", 0) or 0
@@ -643,7 +787,7 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
                     else:
                         _parts = fmt_ratio_parts(rx, tx)
                         _traffic_row = f"  {fmt_ratio_cell(_parts, ratio_l_w, ratio_r_w):>{ratio_total}}"
-                    print(f"  {row_prefix}{node_col:<{col_w}}  {ver:<{ver_w}}{_ip_row_part}{_geo_row_part}  {lat_s:>8}  {up:<8}{_traffic_row}  {flow}")
+                    print(f"  {row_prefix}{node_col:<{col_w}}  {ver:<{ver_w}}{_ip_row_part}{_geo_row_part}  {lat_s:>8} {lat_flag} {ping_s:>9}  {up:<8}{_traffic_row}  {flow}")
 
             print()
             print(HDR)
@@ -657,6 +801,15 @@ def run_cycle(client, peers_extended, geo_enabled, show_ip, interactive=False, e
                     print()
                 print("  Outbound")
                 show(outbound, True)
+            legend = []
+            if lat_flagged:
+                legend.append(f"⚡ = Latency > {LATENCY_PING_RATIO}× Ping (possible VPN exit / relay)")
+            if any(kind == "tcp" for _, kind in ping_ms.values()):
+                legend.append("Ping: t = TCP connect to peer port (ICMP filtered)")
+            if legend:
+                print()
+                for line in legend:
+                    print(f"  {line}")
 
     print()
     return outbound_numbered, container
@@ -758,56 +911,75 @@ def interactive_loop(client, refresh_interval, peers_extended, geo_enabled, show
     traffic_extended = extended_traffic  # local, toggled with 'x'
 
     old_settings = termios.tcgetattr(sys.stdin)
+    # cbreak wird EINMAL für die gesamte Session gesetzt (nicht erst nach jedem
+    # run_cycle()). Andernfalls bleibt das Terminal während der Ausführung im
+    # zeilengepufferten Modus des alten old_settings, und das anschließende
+    # tty.setcbreak(..., TCSAFLUSH) verwirft dabei sogar noch ungelesene
+    # Eingaben – eine während einer langsamen Ausführung gedrückte Taste wie
+    # 'q' würde so nie ankommen.
+    tty.setcbreak(sys.stdin.fileno())
     try:
         while True:
+            cycle_start = time.monotonic()
             buf = io.StringIO()
             with contextlib.redirect_stdout(buf):
                 outbound_peers, container = run_cycle(
                     client, peers_extended, geo_enabled, show_ip, interactive=True,
                     extended_traffic=traffic_extended
                 )
+                cycle_duration = time.monotonic() - cycle_start
+                if cycle_duration >= refresh_interval:
+                    warn(f"Update dauerte {cycle_duration:.1f}s – "
+                         f"länger als das Intervall ({refresh_interval}s). "
+                         f"Intervall (refresh_interval) erhöhen.")
+                elif cycle_duration >= refresh_interval * REFRESH_WARN_RATIO:
+                    pct = cycle_duration / refresh_interval * 100
+                    warn(f"Update dauerte {cycle_duration:.1f}s "
+                         f"({pct:.0f}% des {refresh_interval}s-Intervalls) – knapp.")
             sys.stdout.write("\033[2J\033[H" + buf.getvalue())
             sys.stdout.flush()
 
-            deadline = time.monotonic() + refresh_interval
-            tty.setcbreak(sys.stdin.fileno())
-            try:
+            # Timer läuft ab Beginn der Ausführung, nicht erst ab deren Ende –
+            # so verlängert die Update-Laufzeit nicht zusätzlich das Intervall.
+            deadline = cycle_start + refresh_interval
             last_secs = -1
             while True:
                 remaining = max(0.0, deadline - time.monotonic())
                 secs = int(remaining) + (1 if remaining % 1 > 0 else 0)
                 if secs != last_secs:
                     x_label = "RX/TX" if traffic_extended else "detail"
-                        text = f"  [d] Drop peer  [a] Drop all  [x] {x_label}  [q] Beenden  Refresh in {secs}s  "
+                    text = (f"  [d] Drop peer  [a] Drop all  [x] {x_label}  [q] Beenden  "
+                             f"Refresh in {secs}s  (Update: {cycle_duration:.1f}s)  ")
                     sys.stdout.write("\r" + text)
                     sys.stdout.flush()
                     last_secs = secs
 
-                    if remaining <= 0:
-                        break
-
-                    rlist, _, _ = select.select([sys.stdin], [], [], min(remaining, 0.25))
+                # Immer mindestens einmal (nicht-blockierend, wenn remaining
+                # bereits 0 ist) auf Eingabe prüfen – auch wenn die Deadline
+                # schon verstrichen ist, weil die Ausführung selbst länger als
+                # das Intervall dauerte. Sonst wird 'q' & Co. in diesem Fall
+                # nie abgefragt, da sofort in den nächsten Zyklus gesprungen würde.
+                timeout = min(remaining, 0.25) if remaining > 0 else 0
+                rlist, _, _ = select.select([sys.stdin], [], [], timeout)
                 if rlist:
                     ch = sys.stdin.read(1)
                     if ch in ('q', 'Q', '\x03', '\x04'):
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
                         print()
                         return
                     elif ch in ('d', 'D') and outbound_peers and container:
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
                         print()
                         do_drop_workflow(outbound_peers, container)
                         break  # trigger immediate refresh
                     elif ch in ('a', 'A') and outbound_peers and container:
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
                         print()
                         drop_all_workflow(outbound_peers, container)
                         break  # trigger immediate refresh
                     elif ch in ('x', 'X'):
                         traffic_extended = not traffic_extended
                         break  # trigger immediate refresh
-            finally:
-                termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
+
+                if remaining <= 0:
+                    break
 
     except KeyboardInterrupt:
         pass
@@ -829,9 +1001,17 @@ Options:
   -s, --show-ip          Show IP column (hidden by default)
   -x, --extended         Full RX/TX/RX-rate/TX-rate columns (default: ratio only)
   -i [SEC], --interactive [SEC]
-                         Auto-refresh mode (default interval: 10 s)
+                         Auto-refresh mode (overrides the configured interval)
   -?, --help             Show this help and exit
 
+Config file (first match wins, JSON):
+  $PI_STAT_CONFIG
+  ~/.config/pi-stat/config.json
+  <script dir>/pi-stat.json
+
+  Keys:
+    refresh_interval   Auto-refresh interval in seconds (default: 5)
+
 Interactive keys:
   d   Drop one outbound peer
   a   Drop all outbound peers
@@ -853,7 +1033,7 @@ def main():
     interactive       = "-i" in args or "--interactive" in args
     extended_traffic  = "-x" in args or "--extended" in args
 
-    refresh_interval = 10
+    refresh_interval = config_refresh(load_config())
     if interactive:
         for flag in ("-i", "--interactive"):
             if flag in args:

pi-stat.json

@@ -0,0 +1,4 @@
+{
+  "_comment": "refresh_interval in Sekunden, min. 1 (Default: 5)",
+  "refresh_interval": 10
+  }