feat: embed config in server log; replay_sim takes a single log path

ServerLogTask now embeds the full config in its JSON output, matching
SudLogTask — so replay_sim and analyze_log work on server logs without
needing a separate config file.

replay_sim.py switches from two positional args (date_time, sud_name) to
a single log file path, with config and plant params resolved from the
log's embedded "Config"/"PlantParams" sections when present and falling
back to config.json / hardcoded defaults for older logs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/brewpi.py

@@ -137,7 +137,7 @@ if __name__ == '__main__':
 
 	# Continuous server-session log - records from startup to shutdown
 	# regardless of Sud state; written to logs/log_{date_time}.json on exit.
-	server_log_task = ServerLogTask(tc, heater, heater_task, DT_TASK, args.logdir)
+	server_log_task = ServerLogTask(tc, heater, heater_task, DT_TASK, args.logdir, config=config)
 	taskmgr.add(server_log_task)
 
 	# Assign data flow

tasks/server_log.py

@@ -16,12 +16,13 @@ class ServerLogTask(ATask):
 	Sud state — useful for verifying controller and heater behaviour
 	outside of a scheduled brew."""
 
-	def __init__(self, tc: APid, heater: AHeater, heater_task, interval, path='./logs'):
+	def __init__(self, tc: APid, heater: AHeater, heater_task, interval, path='./logs', config=None):
 		ATask.__init__(self, interval)
 		self.tc = tc
 		self.heater = heater
 		self.heater_task = heater_task
 		self.path = path
+		self.config = config
 		self._samples = []
 		self._t0 = time.monotonic()
 		self._run_id = time.strftime("%Y%m%dT%H%M%S", time.localtime())
@@ -47,6 +48,10 @@ class ServerLogTask(ATask):
 		os.makedirs(self.path, exist_ok=True)
 		filename = 'log_{}.json'.format(self._run_id)
 		path = os.path.join(self.path, filename)
+		log_data = {'Name': ''}
+		if self.config is not None:
+			log_data['Config'] = self.config
+		log_data['Samples'] = self._samples
 		with open(path, 'w') as f:
-			json.dump({'Name': '', 'Samples': self._samples}, f, indent='\t')
+			json.dump(log_data, f, indent='\t')
 		print('Server log: wrote {} samples to {}'.format(len(self._samples), filename))

utils/replay_sim.py

@@ -13,18 +13,19 @@ plant reaches setpoint faster, overshoots less, or oscillates less than
 the original logged run, all without touching real hardware.
 
 Usage:
-    python utils/replay_sim.py <date_time> <sud_name>
+    python utils/replay_sim.py logs/log_<date_time>_<name>.json
-    python utils/replay_sim.py <date_time> <sud_name> \\
+    python utils/replay_sim.py logs/log_<date_time>_<name>.json \\
         --heat-kp 0.1 --heat-ki 0.03 --heat-kt 1.0
-    python utils/replay_sim.py <date_time> <sud_name> \\
+    python utils/replay_sim.py logs/log_<date_time>_<name>.json \\
         --plant-M 25 --plant-L 0.15 --ambient 18
 
-Plant params default to water (C=4190 J/kg·K), M=20 kg, L=0.2 W/kg·K,
+PID params and plant params are read from the log's embedded "Config" and
-Td=30 s — pass --plant-* to match the actual batch.  Max heater power is
+"PlantParams" sections when present (logs recorded since the config-in-log
-inferred from the highest power_eff step in the log.
+feature was added).  Pass --config to supply a config file for older logs
+that predate that feature.  Any --<section>-<gain> or --plant-* flag
+overrides just that one value regardless of source.
 
-By default reads PID params from config.json in the repo root.  Any
+Max heater power is inferred from the highest power_eff step in the log.
---<section>-<gain> flag overrides just that one value.
 """
 
 import argparse
@@ -160,32 +161,25 @@ def plot_replay(samples, replay, name, max_power, params_label):
 def main():
     repo_root      = Path(__file__).parent.parent
     default_config = repo_root / 'config.json'
-    default_log_dir = repo_root / 'logs'
 
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
-    parser.add_argument('date_time', help='Timestamp part of log filename, e.g. 20260628T184903')
+    parser.add_argument('log', help='Path to log_*.json file')
-    parser.add_argument('sud_name',  help='Sud name part of log filename, e.g. Sud-0010')
+    parser.add_argument('--config', default=None,
-    parser.add_argument('--log-dir', default=str(default_log_dir),
+                        help='Config file for PID params (default: embedded in log, or config.json)')
-                        help='Log directory (default: %(default)s)')
-    parser.add_argument('--config', default=str(default_config),
-                        help='Config file for base PID params (default: %(default)s)')
     parser.add_argument('--rate-soll', type=float, default=None,
                         help='Heat-rate setpoint [K/min] (default: inferred from log)')
     parser.add_argument('--ambient', type=float, default=None,
-                        help='Ambient temperature [°C] (default: from config ambient_temperature)')
+                        help='Ambient temperature [°C] (default: from config)')
 
-    # Plant model params
+    # Plant model params — all default to None so we can tell "not specified"
-    parser.add_argument('--plant-M',  type=float, default=20.0,  metavar='kg',
+    # and fall back to the log's embedded PlantParams when available.
-                        help='Plant mass [kg] (default: %(default)s)')
+    parser.add_argument('--plant-M',  type=float, default=None, metavar='kg',    help='Plant mass [kg]')
-    parser.add_argument('--plant-C',  type=float, default=4190.0, metavar='J/kgK',
+    parser.add_argument('--plant-C',  type=float, default=None, metavar='J/kgK', help='Specific heat [J/(kg·K)]')
-                        help='Specific heat capacity [J/(kg·K)] (default: %(default)s — water)')
+    parser.add_argument('--plant-L',  type=float, default=None, metavar='W/kgK', help='Heat loss coeff [W/(kg·K)]')
-    parser.add_argument('--plant-L',  type=float, default=0.2,   metavar='W/kgK',
+    parser.add_argument('--plant-Td', type=float, default=None, metavar='s',     help='Transport delay [s]')
-                        help='Heat loss coefficient [W/(kg·K)] (default: %(default)s)')
-    parser.add_argument('--plant-Td', type=float, default=30.0,  metavar='s',
-                        help='Transport delay [s] (default: %(default)s)')
     parser.add_argument('--heater-efficiency', type=float, default=1.0, metavar='0-1',
                         help='Fraction of rated heater power delivered to the plant (default: %(default)s)')
 
@@ -201,44 +195,58 @@ def main():
 
     args = parser.parse_args()
 
-    log_path = Path(args.log_dir) / 'log_{}_{}.json'.format(args.date_time, args.sud_name)
+    log_path = Path(args.log)
     if not log_path.exists():
         print('Error: log file not found: {}'.format(log_path), file=sys.stderr)
         sys.exit(1)
 
-    config_path = Path(args.config)
-    if not config_path.exists():
-        print('Error: config file not found: {}'.format(config_path), file=sys.stderr)
-        sys.exit(1)
-
     with open(log_path) as f:
         log = json.load(f)
+
+    # Config: prefer embedded in log, then --config arg, then default config.json.
+    config = log.get('Config')
+    if config is None:
+        config_path = Path(args.config) if args.config else default_config
+        if config_path.exists():
             with open(config_path) as f:
                 config = json.load(f)
+        else:
+            print('Error: no config embedded in log and config file not found: {}'.format(config_path),
+                  file=sys.stderr)
+            sys.exit(1)
+
+    # Plant params: prefer log's PlantParams[0], then --plant-* flags, then hardcoded defaults.
+    log_plant = log['PlantParams'][0]['params'] if log.get('PlantParams') else None
+    plant_params = {
+        'M':  args.plant_M  if args.plant_M  is not None else (log_plant['M']  if log_plant else 20.0),
+        'C':  args.plant_C  if args.plant_C  is not None else (log_plant['C']  if log_plant else 4190.0),
+        'L':  args.plant_L  if args.plant_L  is not None else (log_plant['L']  if log_plant else 0.2),
+        'Td': args.plant_Td if args.plant_Td is not None else (log_plant['Td'] if log_plant else 30.0),
+    }
 
     samples    = log['Samples']
-    name        = log.get('Name', '{}_{}'.format(args.date_time, args.sud_name))
+    name       = log.get('Name', log_path.stem)
     pid_params = _apply_gain_overrides(config['TempCtrl'], args)
     dt         = (samples[1]['t'] - samples[0]['t']) if len(samples) > 1 else 1.0
     max_power  = _infer_max_power(samples)
     rate_soll  = args.rate_soll if args.rate_soll is not None else _infer_heatrate_soll_set(samples)
     ambient    = args.ambient   if args.ambient   is not None else config.get('ambient_temperature', 20.0)
 
-    plant_params = {'M': args.plant_M, 'C': args.plant_C, 'L': args.plant_L, 'Td': args.plant_Td}
-
     any_override = any(
         getattr(args, '{}_{}'.format(p, g)) is not None
         for p in ('hold', 'heat', 'cool')
         for g in ('kp', 'ki', 'kd', 'kt')
     )
-    params_label = 'candidate' if any_override else 'config'
+    config_source = 'log' if log.get('Config') else 'file'
+    params_label  = 'candidate' if any_override else config_source
 
     print('Log:    {} ({} samples, dt={:.1f} s)'.format(name, len(samples), dt))
     print('Power:  max={:.0f} W'.format(max_power))
     print('Rate:   heatrate_soll_set={:.2f} K/min'.format(rate_soll))
-    print('Plant:  M={M} kg  C={C} J/kgK  L={L} W/kgK  Td={Td} s  ambient={amb} °C  heater_efficiency={eff}'.format(
+    print('Plant:  M={M} kg  C={C:.0f} J/kgK  L={L} W/kgK  Td={Td} s  ambient={amb} °C  heater_efficiency={eff}'.format(
         amb=ambient, eff=args.heater_efficiency, **plant_params))
-    print('Params: {}'.format('overridden' if any_override else 'from config'))
+    print('Params: {} ({})'.format('overridden' if any_override else 'from {}'.format(config_source),
+                                   'log' if log_plant else 'defaults'))
     print()
     for section in ('Hold', 'Heat', 'Cool'):
         p = pid_params[section]