Update audit document to reflect implemented changes

Co-authored-by: ishaan <ishaan@berri.ai>

docs/external_dependencies_audit.md

@@ -177,67 +177,41 @@ export LITELLM_LOCAL_MODEL_COST_MAP=True
 
 ---
 
-## Proposed Code Changes for Enhanced Safety
+## Implemented Code Changes
 
-### 1. Add Validation to `get_model_cost_map.py`
+### 1. Runtime Validation in `get_model_cost_map.py` ✅ IMPLEMENTED
 
-```python
-def validate_model_cost_map(data: dict) -> bool:
-    """Validate that fetched data is a valid model cost map."""
-    if not isinstance(data, dict):
-        return False
-    if len(data) < 100:  # Sanity check - should have many models
-        return False
-    # Check a sample of entries have required fields
-    for key, value in list(data.items())[:10]:
-        if key == "sample_spec":
-            continue
-        if not isinstance(value, dict):
-            return False
-        if "litellm_provider" not in value:
-            return False
-    return True
+The `get_model_cost_map()` function now:
+- Validates JSON structure before accepting remote data
+- Checks for required fields (`litellm_provider`)
+- Validates mode values against allowed list
+- Validates numeric cost fields
+- Falls back to local backup if validation fails
+- Logs warnings when falling back
 
-def get_model_cost_map(url: str) -> dict:
-    # ... existing code ...
-    try:
-        response = httpx.get(url, timeout=5)
-        response.raise_for_status()
-        content = response.json()
-        
-        # NEW: Validate before accepting
-        if not validate_model_cost_map(content):
-            verbose_logger.warning(
-                "Remote model cost map failed validation, using local backup"
-            )
-            return _load_local_backup()
-        
-        return content
-    except Exception:
-        return _load_local_backup()
-```
+### 2. Enhanced CI Validation ✅ IMPLEMENTED
 
-### 2. Enhanced CI Validation
+`.github/workflows/test-model-map.yaml` now:
+- Validates JSON syntax (fast fail with `jq`)
+- Runs comprehensive schema validation via `scripts/validate_model_cost_map.py`
+- Validates both main file and backup file
+- Checks backup freshness
 
-Add comprehensive validation to `.github/workflows/test-model-map.yaml`:
+### 3. Validation Script ✅ IMPLEMENTED
 
-```yaml
-- name: Validate model_prices_and_context_window.json
-  run: |
-    python scripts/validate_model_cost_map.py
-```
+`scripts/validate_model_cost_map.py` provides:
+- Validates all entries have required fields
+- Checks mode values against allowed modes
+- Validates numeric fields are actually numeric
+- Sanity checks for suspiciously high costs
+- Detailed error reporting with exit codes for CI
 
-### 3. Add Monitoring/Alerting
+### 4. Observability ✅ IMPLEMENTED
 
-Log when falling back to local backup:
-
-```python
-if using_local_backup:
-    verbose_logger.warning(
-        "Using local model cost map backup. "
-        "Remote fetch failed or returned invalid data."
-    )
-```
+The code now logs warnings when:
+- Falling back to local backup due to network errors
+- Falling back due to validation failures
+- Using local backup mode
 
 ---