1.3: Fix files parameter in agent.py — attachments now visible to LLM

Previously respond() accepted files but silently dropped them.
Now when files are attached:
- Images are base64-encoded as image_url content parts
- Text files are read and inlined as text content parts
- The last user message is converted to multipart format

Follows the same encoding pattern used in tools/image.py.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cheddahbot/agent.py

@@ -2,10 +2,12 @@
 
 from __future__ import annotations
 
+import base64
 import json
 import logging
 import uuid
 from collections.abc import Generator
+from pathlib import Path
 
 from .config import Config
 from .db import Database
@@ -16,6 +18,49 @@ log = logging.getLogger(__name__)
 
 MAX_TOOL_ITERATIONS = 5
 
+_IMAGE_MIME = {
+    ".png": "image/png",
+    ".jpg": "image/jpeg",
+    ".jpeg": "image/jpeg",
+    ".gif": "image/gif",
+    ".webp": "image/webp",
+    ".bmp": "image/bmp",
+}
+
+
+def _build_file_content_parts(files: list[str]) -> list[dict]:
+    """Encode file attachments as content parts for the LLM message.
+
+    Images → base64 image_url parts; text files → inline text parts.
+    """
+    parts: list[dict] = []
+    for file_path in files:
+        p = Path(file_path).resolve()
+        if not p.exists():
+            parts.append({"type": "text", "text": f"[File not found: {file_path}]"})
+            continue
+
+        suffix = p.suffix.lower()
+        if suffix in _IMAGE_MIME:
+            try:
+                data = base64.b64encode(p.read_bytes()).decode("utf-8")
+                mime = _IMAGE_MIME[suffix]
+                parts.append({
+                    "type": "image_url",
+                    "image_url": {"url": f"data:{mime};base64,{data}"},
+                })
+            except Exception as e:
+                parts.append({"type": "text", "text": f"[Error reading image {p.name}: {e}]"})
+        else:
+            try:
+                text = p.read_text(encoding="utf-8", errors="replace")
+                if len(text) > 10000:
+                    text = text[:10000] + "\n... (truncated)"
+                parts.append({"type": "text", "text": f"[File: {p.name}]\n{text}"})
+            except Exception as e:
+                parts.append({"type": "text", "text": f"[Error reading {p.name}: {e}]"})
+    return parts
+
 
 class Agent:
     def __init__(self, config: Config, db: Database, llm: LLMAdapter):
@@ -73,6 +118,20 @@ class Agent:
             system_prompt, history, self.config.memory.max_context_messages
         )
 
+        # If files are attached, replace the last user message with multipart content
+        if files:
+            file_parts = _build_file_content_parts(files)
+            if file_parts:
+                # Find the last user message and convert to multipart
+                for i in range(len(messages) - 1, -1, -1):
+                    if messages[i]["role"] == "user":
+                        text_content = messages[i]["content"]
+                        messages[i]["content"] = [
+                            {"type": "text", "text": text_content},
+                            *file_parts,
+                        ]
+                        break
+
         # Agent loop: LLM call → tool execution → repeat
         seen_tool_calls: set[str] = set()  # track (name, args_json) to prevent duplicates