feat(config): add Pydantic config models, tests, docs and infra notes

src/server/models/config.py

@@ -0,0 +1,66 @@
+from typing import List, Optional
+
+from pydantic import BaseModel, Field
+
+
+class SchedulerConfig(BaseModel):
+    enabled: bool = Field(
+        default=True, description="Whether the scheduler is enabled"
+    )
+    interval_minutes: int = Field(
+        default=60, ge=1, description="Scheduler interval in minutes"
+    )
+
+    # ge=1 on the Field enforces a positive interval; no custom validator
+    # is required.
+
+
+class LoggingConfig(BaseModel):
+    level: str = Field(default="INFO", description="Logging level")
+    file: Optional[str] = Field(
+        default=None, description="Optional file path for log output"
+    )
+    max_bytes: Optional[int] = Field(
+        default=None, ge=0, description="Max bytes per log file for rotation"
+    )
+    backup_count: Optional[int] = Field(
+        default=3, ge=0, description="Number of rotated log files to keep"
+    )
+
+
+class ValidationResult(BaseModel):
+    valid: bool = Field(..., description="Whether the configuration is valid")
+    errors: Optional[List[str]] = Field(
+        default_factory=list, description="List of validation error messages"
+    )
+
+
+class ConfigResponse(BaseModel):
+    scheduler: SchedulerConfig
+    logging: LoggingConfig
+    other: Optional[dict] = Field(
+        default_factory=dict, description="Other arbitrary config values"
+    )
+
+
+class ConfigUpdate(BaseModel):
+    scheduler: Optional[SchedulerConfig] = None
+    logging: Optional[LoggingConfig] = None
+    other: Optional[dict] = None
+
+    def apply_to(self, current: ConfigResponse) -> ConfigResponse:
+        """Return a new ConfigResponse with updates applied to the current
+        config.
+        """
+        # Use model_dump for compatibility with Pydantic v2+ (avoids deprecation)
+        data = current.model_dump()
+        if self.scheduler is not None:
+            data["scheduler"] = self.scheduler.model_dump()
+        if self.logging is not None:
+            data["logging"] = self.logging.model_dump()
+        if self.other is not None:
+            # shallow merge
+            merged = dict(current.other or {})
+            merged.update(self.other)
+            data["other"] = merged
+        return ConfigResponse(**data)