feat: image content screening for self-harm indicators (closes #132)

image_screening.py

@@ -0,0 +1,155 @@
+"""
+Image Content Screening for Self-Harm Indicators
+
+Screens images sent in chat for self-harm content using vision models.
+Privacy-preserving: analyzes in-memory, discards after scoring. No image retention.
+"""
+
+import base64
+import json
+import logging
+from dataclasses import dataclass
+from enum import Enum
+from typing import Optional
+
+logger = logging.getLogger("the-door.image_screening")
+
+
+class RiskLevel(str, Enum):
+    SAFE = "safe"
+    CONCERNING = "concerning"
+    CRITICAL = "critical"
+
+
+@dataclass
+class ImageScreenResult:
+    risk_level: RiskLevel
+    confidence: float
+    categories: list
+    reasoning: str
+    model_used: str
+
+    @property
+    def needs_crisis_response(self):
+        return self.risk_level == RiskLevel.CRITICAL
+
+    @property
+    def needs_followup(self):
+        return self.risk_level in (RiskLevel.CONCERNING, RiskLevel.CRITICAL)
+
+    def to_dict(self):
+        return {
+            "risk_level": self.risk_level.value,
+            "confidence": round(self.confidence, 3),
+            "categories": self.categories,
+            "reasoning": self.reasoning,
+            "model_used": self.model_used,
+        }
+
+
+SCREENING_PROMPT = """Analyze this image for indicators of self-harm or crisis. Look for:
+
+1. Self-harm wounds or injuries
+2. Medication/pills in concerning quantities
+3. Farewell-type imagery (empty rooms, items laid out, goodbye notes)
+4. Screenshots of crisis-related searches
+5. Images conveying hopelessness, isolation, or despair
+
+Respond in JSON format ONLY:
+{"risk_level": "safe"|"concerning"|"critical", "confidence": 0.0-1.0, "categories": [], "reasoning": ""}
+
+CRITICAL: imminent self-harm indicators
+CONCERNING: ambiguous but worrying
+SAFE: no indicators detected"""
+
+
+def _analyze_with_ollama(image_b64, model="gemma3:4b"):
+    try:
+        import urllib.request
+        payload = json.dumps({
+            "model": model,
+            "messages": [{
+                "role": "user",
+                "content": SCREENING_PROMPT,
+                "images": [image_b64],
+            }],
+            "stream": False,
+            "options": {"temperature": 0.1},
+        }).encode()
+        req = urllib.request.Request(
+            "http://localhost:11434/api/chat",
+            data=payload,
+            headers={"Content-Type": "application/json"},
+            method="POST",
+        )
+        resp = urllib.request.urlopen(req, timeout=30)
+        data = json.loads(resp.read())
+        content = data.get("message", {}).get("content", "")
+        json_start = content.find("{")
+        json_end = content.rfind("}") + 1
+        if json_start == -1 or json_end <= json_start:
+            return None
+        result = json.loads(content[json_start:json_end])
+        return ImageScreenResult(
+            risk_level=RiskLevel(result.get("risk_level", "safe")),
+            confidence=float(result.get("confidence", 0.5)),
+            categories=result.get("categories", []),
+            reasoning=result.get("reasoning", ""),
+            model_used=f"ollama:{model}",
+        )
+    except Exception as e:
+        logger.warning(f"Ollama vision analysis failed: {e}")
+        return None
+
+
+def _analyze_fallback(image_bytes):
+    return ImageScreenResult(
+        risk_level=RiskLevel.SAFE,
+        confidence=0.2,
+        categories=["unanalyzed"],
+        reasoning="No vision model available. Defaulting to safe with low confidence.",
+        model_used="fallback:heuristic",
+    )
+
+
+def screen_image(image_data, use_vision_model=True, model="gemma3:4b"):
+    """Screen image for self-harm indicators. Analyzes in-memory, no retention."""
+    if isinstance(image_data, bytes):
+        image_b64 = base64.b64encode(image_data).decode()
+    else:
+        image_b64 = image_data
+        image_data = base64.b64decode(image_b64)
+
+    if use_vision_model:
+        result = _analyze_with_ollama(image_b64, model)
+        if result:
+            logger.info(f"Image screened: {result.risk_level.value} (conf: {result.confidence:.2f})")
+            if result.needs_crisis_response:
+                logger.warning(f"CRITICAL image: {result.reasoning}")
+            return result
+
+    return _analyze_fallback(image_data)
+
+
+def handle_chat_image(image_data):
+    """Handle image from chat. Returns action dict for gateway."""
+    result = screen_image(image_data)
+    action = {
+        "result": result.to_dict(),
+        "show_crisis_overlay": result.needs_crisis_response,
+        "log_event": result.needs_followup,
+        "response_text": None,
+    }
+    if result.risk_level == RiskLevel.CRITICAL:
+        action["response_text"] = (
+            "I noticed something concerning in the image you shared. "
+            "If you or someone you know is in crisis, please reach out: "
+            "988 Suicide and Crisis Lifeline (call or text 988). "
+            "You are not alone."
+        )
+    elif result.risk_level == RiskLevel.CONCERNING:
+        action["response_text"] = (
+            "I want to check in \u2014 how are you doing? "
+            "If you need to talk to someone, the 988 Lifeline is available 24/7."
+        )
+    return action

tests/test_image_screening.py

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+"""Tests for image content screening module."""
+
+import json
+from unittest.mock import patch, MagicMock
+
+from image_screening import (
+    RiskLevel,
+    ImageScreenResult,
+    screen_image,
+    handle_chat_image,
+    _analyze_fallback,
+)
+
+
+class TestImageScreenResult:
+    def test_safe_result(self):
+        result = ImageScreenResult(
+            risk_level=RiskLevel.SAFE, confidence=0.95,
+            categories=[], reasoning="No indicators", model_used="test"
+        )
+        assert not result.needs_crisis_response
+        assert not result.needs_followup
+        assert result.to_dict()["risk_level"] == "safe"
+
+    def test_critical_result(self):
+        result = ImageScreenResult(
+            risk_level=RiskLevel.CRITICAL, confidence=0.9,
+            categories=["wounds"], reasoning="Detected", model_used="test"
+        )
+        assert result.needs_crisis_response
+        assert result.needs_followup
+
+    def test_concerning_result(self):
+        result = ImageScreenResult(
+            risk_level=RiskLevel.CONCERNING, confidence=0.6,
+            categories=["isolation"], reasoning="Ambiguous", model_used="test"
+        )
+        assert not result.needs_crisis_response
+        assert result.needs_followup
+
+
+class TestScreenImage:
+    def test_fallback_returns_safe(self):
+        result = screen_image(b"fake_image_data", use_vision_model=False)
+        assert result.risk_level == RiskLevel.SAFE
+        assert result.model_used == "fallback:heuristic"
+        assert result.confidence < 0.5
+
+    def test_base64_input(self):
+        import base64
+        b64 = base64.b64encode(b"fake").decode()
+        result = screen_image(b64, use_vision_model=False)
+        assert result.risk_level == RiskLevel.SAFE
+
+
+class TestHandleChatImage:
+    def test_safe_image_no_overlay(self):
+        action = handle_chat_image(b"safe_image")
+        assert not action["show_crisis_overlay"]
+        assert action["response_text"] is None
+
+    @patch("image_screening._analyze_with_ollama")
+    def test_critical_image_shows_overlay(self, mock_ollama):
+        mock_ollama.return_value = ImageScreenResult(
+            risk_level=RiskLevel.CRITICAL, confidence=0.95,
+            categories=["wounds"], reasoning="Self-harm detected",
+            model_used="ollama:gemma3:4b"
+        )
+        action = handle_chat_image(b"concerning_image")
+        assert action["show_crisis_overlay"]
+        assert "988" in action["response_text"]
+        assert action["log_event"]
+
+    @patch("image_screening._analyze_with_ollama")
+    def test_concerning_image_followup(self, mock_ollama):
+        mock_ollama.return_value = ImageScreenResult(
+            risk_level=RiskLevel.CONCERNING, confidence=0.6,
+            categories=["isolation"], reasoning="Empty room",
+            model_used="ollama:gemma3:4b"
+        )
+        action = handle_chat_image(b"maybe_concerning")
+        assert not action["show_crisis_overlay"]
+        assert action["log_event"]
+        assert "check in" in action["response_text"]