feat(core): add config and structured logging

Implement pydantic-settings based configuration with environment variable
support and structlog integration for JSON/console output modes.

src/veritext/core/config.py

@@ -0,0 +1,59 @@
+"""Configuration management using pydantic-settings."""
+
+from pathlib import Path
+from typing import Literal
+
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class VeritextSettings(BaseSettings):
+    """Configuration settings for Veritext."""
+
+    model_config = SettingsConfigDict(
+        env_prefix="VERITEXT_",
+        env_file=".env",
+        env_file_encoding="utf-8",
+        extra="ignore",
+    )
+
+    # Logging settings
+    log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR"] = Field(
+        default="INFO",
+        description="Logging level",
+    )
+    log_format: Literal["console", "json"] = Field(
+        default="console",
+        description="Log output format",
+    )
+
+    # Benchmark settings
+    benchmark_storage_path: Path = Field(
+        default=Path("benchmarks"),
+        description="Path to benchmark storage directory",
+    )
+
+    # Tokenisation defaults
+    tokeniser_lowercase: bool = Field(
+        default=True,
+        description="Whether to lowercase tokens by default",
+    )
+    tokeniser_remove_punctuation: bool = Field(
+        default=True,
+        description="Whether to remove punctuation by default",
+    )
+
+    # Semantic similarity settings (when available)
+    semantic_model: str = Field(
+        default="all-MiniLM-L6-v2",
+        description="Default sentence-transformers model",
+    )
+    semantic_cache_embeddings: bool = Field(
+        default=True,
+        description="Whether to cache embeddings",
+    )
+
+
+def get_settings() -> VeritextSettings:
+    """Get the current settings instance."""
+    return VeritextSettings()

src/veritext/core/logging.py

@@ -0,0 +1,79 @@
+"""Structured logging configuration using structlog."""
+
+import logging
+import sys
+from typing import Any
+
+import structlog
+
+from veritext.core.config import get_settings
+
+
+def configure_logging(
+    level: str | None = None,
+    log_format: str | None = None,
+) -> None:
+    """
+    Configure structlog for the application.
+
+    Args:
+        level: Log level (DEBUG, INFO, WARNING, ERROR). Uses settings if not provided.
+        log_format: Output format (console, json). Uses settings if not provided.
+    """
+    settings = get_settings()
+    level = level or settings.log_level
+    log_format = log_format or settings.log_format
+
+    # Configure standard library logging
+    logging.basicConfig(
+        format="%(message)s",
+        stream=sys.stderr,
+        level=getattr(logging, level),
+    )
+
+    # Shared processors
+    shared_processors: list[Any] = [
+        structlog.contextvars.merge_contextvars,
+        structlog.processors.add_log_level,
+        structlog.processors.TimeStamper(fmt="iso"),
+        structlog.stdlib.PositionalArgumentsFormatter(),
+        structlog.processors.StackInfoRenderer(),
+        structlog.processors.UnicodeDecoder(),
+    ]
+
+    if log_format == "json":
+        # JSON output for production/log aggregation
+        processors = [
+            *shared_processors,
+            structlog.processors.format_exc_info,
+            structlog.processors.JSONRenderer(),
+        ]
+    else:
+        # Console output for development
+        processors = [
+            *shared_processors,
+            structlog.dev.ConsoleRenderer(colors=True),
+        ]
+
+    structlog.configure(
+        processors=processors,
+        wrapper_class=structlog.make_filtering_bound_logger(
+            getattr(logging, level),
+        ),
+        context_class=dict,
+        logger_factory=structlog.PrintLoggerFactory(),
+        cache_logger_on_first_use=True,
+    )
+
+
+def get_logger(name: str | None = None) -> structlog.stdlib.BoundLogger:
+    """
+    Get a logger instance.
+
+    Args:
+        name: Logger name. Uses 'veritext' if not provided.
+
+    Returns:
+        A bound logger instance.
+    """
+    return structlog.get_logger(name or "veritext")