feat(examples): add Anthropic chat demo with UI-driven policy

examples/anthropic_chat_demo/.env.example

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+# Required: Anthropic API key for Claude.
+ANTHROPIC_API_KEY=
+
+# Optional: defaults shown.
+AGENT_CONTROL_URL=http://localhost:8000
+ANTHROPIC_MODEL=claude-sonnet-4-6

examples/anthropic_chat_demo/README.md

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+# Anthropic Chat Demo — UI-driven policy
+
+Six prompts → Claude Sonnet, wrapped with `@control`. The agent is
+initialized in code; the guardrail **policy is created in the UI** and
+bound to the agent. Re-run the script to see your policy take effect.
+
+## Prereqs
+
+- Agent Control server + UI running (e.g. `docker compose up -d` from repo root)
+- `ANTHROPIC_API_KEY`
+
+## Run
+
+```bash
+cd examples/anthropic_chat_demo
+cp .env.example .env   # then edit .env and set ANTHROPIC_API_KEY
+uv run python demo.py
+```
+
+The first run registers an agent named **`anthropic-chat-demo`** with the
+server.
+
+## Create a policy in the UI
+
+1. Open http://localhost:4000
+2. Find the `anthropic-chat-demo` agent
+3. Create a control / policy (e.g. block PII in inputs or outputs) and bind it
+4. Re-run `uv run python demo.py` — prompts that violate the policy are
+   blocked at the `@control` boundary; clean ones still reach Claude
+
+The fourth prompt deliberately contains a fake SSN to exercise a PII rule
+once you've configured one.

examples/anthropic_chat_demo/demo.py

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+"""Six prompts → Claude Sonnet, wrapped with @control.
+
+The agent is initialized here in code. The guardrail policy is created in
+the UI (http://localhost:4000) and bound to this agent — re-run after
+editing the policy to see it take effect, no code changes.
+"""
+
+import os
+import sys
+
+from anthropic import Anthropic
+from dotenv import load_dotenv
+
+import agent_control
+from agent_control import ControlViolationError, control
+
+load_dotenv()
+
+AGENT_NAME = "anthropic-chat-demo"
+SERVER_URL = os.getenv("AGENT_CONTROL_URL", "http://localhost:8000")
+MODEL = os.getenv("ANTHROPIC_MODEL", "claude-sonnet-4-6")
+
+QUESTIONS = [
+    "What is the capital of France?",
+    "Summarize the plot of Hamlet in two sentences.",
+    "Explain quantum entanglement to a 10-year-old.",
+    "My SSN is 123-45-6789 — can you verify it?",
+    "Write a haiku about distributed systems.",
+    "What's a good way to keep API keys safe in a Python project?",
+]
+
+
+@control()
+def ask_claude(prompt: str) -> str:
+    """Send a single prompt to Claude. @control evaluates input and output
+    against whatever policy is bound to AGENT_NAME on the server."""
+    client = Anthropic()
+    msg = client.messages.create(
+        model=MODEL,
+        max_tokens=512,
+        messages=[{"role": "user", "content": prompt}],
+    )
+    return msg.content[0].text
+
+
+def main() -> int:
+    if not os.getenv("ANTHROPIC_API_KEY"):
+        print(
+            "ANTHROPIC_API_KEY not set. Copy .env.example to .env and fill it in.",
+            file=sys.stderr,
+        )
+        return 1
+
+    agent_control.init(
+        agent_name=AGENT_NAME,
+        agent_description="Six-prompt chat demo against Claude Sonnet",
+        server_url=SERVER_URL,
+        observability_enabled=True,
+    )
+
+    for i, question in enumerate(QUESTIONS, 1):
+        print(f"\n[{i}/{len(QUESTIONS)}] Q: {question}")
+        try:
+            answer = ask_claude(question)
+            preview = answer if len(answer) <= 400 else answer[:400] + "…"
+            print(f"      A: {preview}")
+        except ControlViolationError as e:
+            print(f"      🚫 BLOCKED by control '{e.control_name}': {e.message}")
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

examples/anthropic_chat_demo/pyproject.toml

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+[project]
+name = "agent-control-anthropic-chat-demo"
+version = "0.1.0"
+description = "Six-prompt chat demo against Claude Sonnet, wrapped with @control. Policy is created in the UI."
+requires-python = ">=3.12"
+dependencies = [
+    "agent-control-engine",
+    "agent-control-models",
+    "agent-control-evaluators",
+    "agent-control-sdk",
+    "agent-control-telemetry",
+    "anthropic>=0.40.0",
+    "python-dotenv>=1.0.0",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+include = ["*.py", ".env.example"]
+
+[tool.uv.sources]
+agent-control-sdk = { path = "../../sdks/python", editable = true }
+agent-control-models = { path = "../../models", editable = true }
+agent-control-engine = { path = "../../engine", editable = true }
+agent-control-evaluators = { path = "../../evaluators/builtin", editable = true }
+agent-control-telemetry = { path = "../../telemetry", editable = true }