Docs: Update dev log to reflect JSON export implementation

Updated dev record to document JSON export feature instead of markdown:
- Environment-aware paths (local vs HF Spaces)
- Full error message preservation
- Pretty formatted for readability and code processing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

dev/dev_260103_16_huggingface_llm_integration.md

@@ -117,11 +117,14 @@ Successfully integrated HuggingFace LLM API as free LLM fallback tier, completin
    - Updated `validate_environment()` to check HF_TOKEN at agent startup
    - Shows ⚠️ WARNING if HF_TOKEN missing
 
-3. **app.py** - Updated UI and added export functionality
+3. **app.py** - Updated UI and added JSON export functionality
    - Added HF_TOKEN to `check_api_keys()` display in Test & Debug tab
-   - Added `export_results_to_markdown()` - Exports evaluation results to ~/Downloads/gaia_results_TIMESTAMP.md
-   - Updated `run_and_submit_all()` - ALL return paths now export results (success and error cases)
-   - Added export_output UI component in Full Evaluation tab to display exported file path
+   - Added `export_results_to_json()` - Exports evaluation results as clean JSON
+     - Local: ~/Downloads/gaia_results_TIMESTAMP.json
+     - HF Spaces: ./exports/gaia_results_TIMESTAMP.json (environment-aware)
+     - Full error messages preserved (no truncation), easy code processing
+   - Updated `run_and_submit_all()` - ALL return paths now export results
+   - Added gr.File download button - Direct download instead of text display
 
 4. **src/tools/__init__.py** - Fixed TOOLS schema bug (earlier in session)
    - Changed parameters from list to dict format
@@ -327,10 +330,13 @@ def validate_environment() -> List[str]:
 3. **app.py**
    - Updated `check_api_keys()` - Added HF_TOKEN status display in Test & Debug tab
    - UI now shows: "HF_TOKEN (HuggingFace): ✓ SET" or "✗ MISSING"
-   - Added `export_results_to_markdown(results_log, submission_status)` - Export evaluation results to markdown file
-   - Updated `run_and_submit_all()` - ALL return paths now export results to ~/Downloads/gaia_results_TIMESTAMP.md
-   - Added export_output UI component in Full Evaluation tab - Displays exported file path to user
-   - Updated run_button click handler - Now outputs 3 values (status, table, export_path)
+   - Added `export_results_to_json(results_log, submission_status)` - Export evaluation results as JSON
+     - Local: ~/Downloads/gaia_results_TIMESTAMP.json
+     - HF Spaces: ./exports/gaia_results_TIMESTAMP.json
+     - Pretty formatted (indent=2), full error messages, easy code processing
+   - Updated `run_and_submit_all()` - ALL return paths now export results
+   - Added gr.File download button - Direct download of JSON file
+   - Updated run_button click handler - Outputs 3 values (status, table, export_path)
 
 4. **src/tools/__init__.py** (Fixed earlier in session)
    - Fixed TOOLS schema bug - Changed parameters from list to dict format