Add mock mode support - demo runs without Tinker API key

Author: haasonsaas

logger.py

@@ -0,0 +1,92 @@
+"""
+Structured logging utilities for the training loop.
+"""
+
+import json
+import logging
+import sys from datetime import datetime
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+
+class StructuredLogger:
+    """JSON-structured logger for training metrics and events."""
+    
+    def __init__(self, run_dir: Optional[Path] = None, log_level: int = logging.INFO):
+        """
+        Initialize structured logger.
+        
+        Args:
+            run_dir: Directory to write metrics.jsonl. If None, logs to stdout only.
+            log_level: Logging level (default INFO).
+        """
+        self.run_dir = run_dir
+        self.run_id = datetime.now().strftime("%Y%m%d_%H%M%S")
+        
+        if run_dir:
+            run_dir.mkdir(parents=True, exist_ok=True)
+            self.metrics_file = run_dir / "metrics.jsonl"
+        else:
+            self.metrics_file = None
+        
+        self.logger = logging.getLogger("tinker_eval_loop")
+        self.logger.setLevel(log_level)
+        
+        handler = logging.StreamHandler(sys.stdout)
+        handler.setLevel(log_level)
+        formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
+        handler.setFormatter(formatter)
+        self.logger.addHandler(handler)
+    
+    def log_event(self, event_type: str, data: Dict[str, Any], level: str = "INFO"):
+        """
+        Log a structured event.
+        
+        Args:
+            event_type: Type of event (e.g., "training_start", "eval_complete").
+            data: Event data dictionary.
+            level: Log level (INFO, WARNING, ERROR).
+        """
+        log_entry = {
+            "timestamp": datetime.now().isoformat(),
+            "run_id": self.run_id,
+            "event": event_type,
+            **data
+        }
+        
+        if self.metrics_file:
+            with open(self.metrics_file, "a") as f:
+                f.write(json.dumps(log_entry) + "\n")
+        
+        log_fn = getattr(self.logger, level.lower(), self.logger.info)
+        log_fn(f"[{event_type}] {json.dumps(data, indent=None)}")
+    
+    def log_training_step(self, round_num: int, step: int, lr: float, loss: Optional[float] = None):
+        """Log a training step."""
+        self.log_event("training_step", {
+            "round": round_num,
+            "step": step,
+            "learning_rate": lr,
+            "loss": loss,
+        })
+    
+    def log_evaluation(self, round_num: int, score: float, threshold: float, passed: bool, metrics: Optional[Dict] = None):
+        """Log an evaluation result."""
+        self.log_event("evaluation", {
+            "round": round_num,
+            "score": score,
+            "threshold": threshold,
+            "passed": passed,
+            "metrics": metrics or {},
+        })
+    
+    def log_checkpoint(self, round_num: int, checkpoint_uri: str):
+        """Log a checkpoint save."""
+        self.log_event("checkpoint", {
+            "round": round_num,
+            "checkpoint_uri": checkpoint_uri,
+        })
+    
+    def log_config(self, config: Dict[str, Any]):
+        """Log the run configuration."""
+        self.log_event("config", config)

run_demo.sh

@@ -7,17 +7,18 @@ echo "╚═══════════════════════
 echo ""
 
 if [ -z "$TINKER_API_KEY" ]; then
-    echo "❌ Error: TINKER_API_KEY environment variable not set"
+    echo "⚠️  No TINKER_API_KEY found - running in MOCK MODE"
     echo ""
-    echo "Please set your Tinker API key:"
+    echo "Mock mode simulates Tinker training locally (no GPU, no cloud calls)."
+    echo "To use real Tinker infrastructure, set:"
     echo "  export TINKER_API_KEY=sk-your-key-here"
     echo ""
-    exit 1
+    export TINKER_MOCK=1
+else
+    echo "✓ Tinker API key found - using real Tinker infrastructure"
+    echo ""
 fi
 
-echo "✓ Tinker API key found"
-echo ""
-
 if [ ! -d ".venv" ]; then
     echo "📦 Creating virtual environment..."
     python3 -m venv .venv

trainer_with_eval.py

@@ -28,11 +28,20 @@
 
 import numpy as np
 
-try:
-    import tinker
-    from tinker import types
-except ImportError:
-    tinker = None
+USE_MOCK = os.getenv("TINKER_MOCK", "0") == "1"
+
+if USE_MOCK:
+    print("[MOCK MODE] Using offline mock Tinker client")
+    from mock_tinker import create_mock_tinker_module
+    tinker = create_mock_tinker_module()
+    types = tinker.types
+else:
+    try:
+        import tinker
+        from tinker import types
+    except ImportError:
+        tinker = None
+        types = None
 
 try:
     from inspect_ai import Task, task