add Signal command and control bot service

Python service for jeeves that communicates over Signal via signal-cli-rest-api.
Implements device verification via safety numbers (unverified devices cannot
run commands until verified over SSH), and a van inventory command that uses
an LLM on BOB (ollama) to parse receipt photos or text lists into structured
inventory data. The LLM backend is configurable to swap models easily.

https://claude.ai/code/session_01AKXQBuVBsW7J1YbukDiQ7A

python/signal_bot/commands/__init__.py

@@ -0,0 +1 @@
+"""Signal bot commands."""

python/signal_bot/commands/inventory.py

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+"""Van inventory command — parse receipts and item lists via LLM."""
+
+from __future__ import annotations
+
+import json
+import logging
+from typing import TYPE_CHECKING, Any
+
+from python.signal_bot.models import InventoryItem, InventoryUpdate
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    from python.signal_bot.llm_client import LLMClient
+    from python.signal_bot.models import SignalMessage
+    from python.signal_bot.signal_client import SignalClient
+
+logger = logging.getLogger(__name__)
+
+SYSTEM_PROMPT = """\
+You are an inventory assistant. Extract items from the input and return ONLY
+a JSON array. Each element must have these fields:
+  - "name": item name (string)
+  - "quantity": integer count (default 1)
+  - "category": category like "food", "tools", "supplies", etc.
+  - "notes": any extra detail (empty string if none)
+
+Example output:
+[{"name": "water bottles", "quantity": 6, "category": "supplies", "notes": "1 gallon each"}]
+
+Return ONLY the JSON array, no other text.\
+"""
+
+IMAGE_PROMPT = "Extract all items from this receipt or inventory photo."
+TEXT_PROMPT = "Extract all items from this inventory list."
+
+
+def parse_llm_response(raw: str) -> list[InventoryItem]:
+    """Parse the LLM JSON response into InventoryItem list."""
+    text = raw.strip()
+    # Strip markdown code fences if present
+    if text.startswith("```"):
+        lines = text.split("\n")
+        lines = [line for line in lines if not line.startswith("```")]
+        text = "\n".join(lines)
+
+    items_data: list[dict[str, Any]] = json.loads(text)
+    return [InventoryItem.model_validate(item) for item in items_data]
+
+
+def load_inventory(path: Path) -> list[InventoryItem]:
+    """Load existing inventory from disk."""
+    if not path.exists():
+        return []
+    data: list[dict[str, Any]] = json.loads(path.read_text())
+    return [InventoryItem.model_validate(item) for item in data]
+
+
+def save_inventory(path: Path, items: list[InventoryItem]) -> None:
+    """Save inventory to disk."""
+    path.parent.mkdir(parents=True, exist_ok=True)
+    data = [item.model_dump() for item in items]
+    path.write_text(json.dumps(data, indent=2) + "\n")
+
+
+def handle_inventory_update(
+    message: SignalMessage,
+    signal: SignalClient,
+    llm: LLMClient,
+    inventory_path: Path,
+) -> InventoryUpdate:
+    """Process an inventory update from a Signal message.
+
+    Accepts either an image (receipt photo) or text list.
+    Uses the LLM to extract structured items, then merges into inventory.
+    """
+    try:
+        if message.attachments:
+            image_data = signal.get_attachment(message.attachments[0])
+            raw_response = llm.chat_with_image(
+                IMAGE_PROMPT,
+                image_data,
+                system=SYSTEM_PROMPT,
+            )
+            source_type = "receipt_photo"
+        elif message.message.strip():
+            raw_response = llm.chat(
+                f"{TEXT_PROMPT}\n\n{message.message}",
+                system=SYSTEM_PROMPT,
+            )
+            source_type = "text_list"
+        else:
+            signal.reply(message, "Send a photo of a receipt or a text list of items to update inventory.")
+            return InventoryUpdate()
+
+        new_items = parse_llm_response(raw_response)
+        existing = load_inventory(inventory_path)
+        merged = _merge_items(existing, new_items)
+        save_inventory(inventory_path, merged)
+
+        summary = _format_summary(new_items)
+        signal.reply(message, f"Inventory updated with {len(new_items)} item(s):\n{summary}")
+
+        return InventoryUpdate(items=new_items, raw_response=raw_response, source_type=source_type)
+
+    except Exception:
+        logger.exception("Failed to process inventory update")
+        signal.reply(message, "Failed to process inventory update. Check logs for details.")
+        return InventoryUpdate()
+
+
+def _merge_items(existing: list[InventoryItem], new: list[InventoryItem]) -> list[InventoryItem]:
+    """Merge new items into existing inventory, summing quantities for matches."""
+    by_name: dict[str, InventoryItem] = {item.name.lower(): item for item in existing}
+    for item in new:
+        key = item.name.lower()
+        if key in by_name:
+            current = by_name[key]
+            by_name[key] = current.model_copy(
+                update={
+                    "quantity": current.quantity + item.quantity,
+                    "category": item.category or current.category,
+                    "notes": item.notes or current.notes,
+                },
+            )
+        else:
+            by_name[key] = item
+    return list(by_name.values())
+
+
+def _format_summary(items: list[InventoryItem]) -> str:
+    """Format items into a readable summary."""
+    lines = [f"  - {item.name} x{item.quantity} [{item.category}]" for item in items]
+    return "\n".join(lines)