Horizon Fidelity Monitor

"Quality is not a model property — it is a conversation property."

Horizon is a real-time conversation health monitor for AI agents. It tracks the structural dynamics of multi-turn conversations — semantic drift, information gain, ontological gap width, temporal desynchronisation, circadian cognitive load, conversation velocity, and causal reachability — dimensions that LLMs do not reliably surface from inside the conversation.

Horizon ships two measurement planes. The conversation plane (above, always present) measures the health of a dialogue turn by turn. The optional mission plane — Memento Mori — measures elapsed calendar time against goals: ages, deadlines, stalls, per-entity latency, and share of a finite horizon. It is inert until you configure a store. See Mission plane.

Horizon is not a manipulation, sycophancy, or human-influence detector — it measures conversation dynamics, not whether an agent is steering or flattering the user. See LEGAL.md §1.

Why an external monitor? LLMs have limited and unreliable self-knowledge: introspection research shows partial self-access that is brittle and degrades on complex or out-of-distribution tasks (Binder et al. 2024; arXiv:2512.12411). So rather than depend on a model reporting its own conversation dynamics, Horizon measures them externally with cheap, deterministic, always-on arithmetic that does not call the model at all.

Why this exists

Multi-turn AI agents lose accuracy. The ICLR 2026 Outstanding Paper "LLMs Get Lost In Multi-Turn Conversation" (Laban, Hayashi, Zhou & Neville — Microsoft Research / Salesforce Research) reports 39% average accuracy degradation across multi-turn evaluation — a structural property that standard observability tools (LangSmith, RAGAS, DeepEval) cannot see because they measure responses, not conversations.

Horizon was built to close that gap. It is observability first: it surfaces conversation dynamics that response-level tools miss, using cheap deterministic arithmetic with zero model calls. In four controlled A/B scenarios where Horizon events drove a re-grounding intervention we measured a +15.7% composite quality lift and 87% fewer hallucination events — but those are synthetic, scripted scenarios with a hand-tuned controller, not a production result. Treat them as promising in-house evidence, not a guaranteed outcome (see Validation and LEGAL.md §5). Every signal — information gain, divergence, estimated ontological gap width, causal reachability — is a standard information-theory or arithmetic measure computed on text embeddings and timestamps; see 4D Spacetime Signals for the full definitions.

• Read the demand proof → ICLR 2026 Outstanding Paper (Laban et al.)
• Read the category argument → docs/content/naming-the-category-conversation-dynamics-monitoring.md
• Read the engineering case → docs/content/why-every-production-agent-needs-conversation-dynamics-monitoring.md

Getting started

Three paths — pick the one that fits your workflow:

Path 1 — Hosted MCP (fastest, zero install)

The fastest way to add Horizon to any Cursor, VS Code, or Claude Desktop workspace. No Python required.

Request an alpha key → open a Discussion, then add the config for your client:

Cursor (~/.cursor/mcp.json):

{
  "mcpServers": {
    "horizon": {
      "url": "https://horizon.leocelis.com/sse",
      "headers": { "Authorization": "Bearer YOUR_KEY_HERE" }
    }
  }
}

VS Code / GitHub Copilot (.vscode/mcp.json in your workspace):

{
  "servers": {
    "horizon": {
      "type": "http",
      "url": "https://horizon.leocelis.com/sse",
      "headers": { "Authorization": "Bearer YOUR_KEY_HERE" }
    }
  }
}

VS Code note: Use "servers" (not "mcpServers") and "type": "http" — VS Code tries Streamable HTTP first and falls back to SSE automatically, so "type": "http" works with the /sse URL.

Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "horizon": {
      "url": "https://horizon.leocelis.com/sse",
      "headers": { "Authorization": "Bearer YOUR_KEY_HERE" }
    }
  }
}

That's it. Reload your MCP client and three tools appear: new_conversation, process_turn, configure_session.

Alpha access: Horizon's hosted endpoint is in private alpha. Keys are distributed to agent developers who want to monitor real projects. Open a Discussion to request one — describe your use case and we'll send a key.

Path 2 — pip install (library integration)

Not yet published to PyPI — until it is, use Path 3 (install from source) below.

pip install horizon-monitor

Verify your install (exercises the full pipeline on 5 canonical scenarios, ~25s):

horizon-validate

Path 3 — MCP server from source

pip install 'horizon-monitor[mcp]'
horizon serve                             # stdio — for Cursor, Claude Desktop
horizon serve --transport sse --port 3847 # SSE — for web/team deployments

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "horizon": { "command": "horizon", "args": ["serve"] }
  }
}

Full Cursor and Claude Desktop setup guides: docs/integrations/

What it monitors

Standard observability tools evaluate individual response quality. Horizon evaluates conversation quality — a structurally different problem:

Horizon does not replace per-response or LLM-judge quality tools. The differentiator is how it measures: deterministic, zero-LLM-call arithmetic on every single turn — effectively free and always-on — versus the alternative of sampled LLM-judge evaluations, which cost per sample and typically run offline or async rather than in real time.

Quickstart

from horizon_monitor import FidelityMonitor
from datetime import datetime, timezone

monitor = FidelityMonitor()
session_id = monitor.new_conversation(metadata={"domain": "technical"})

result = monitor.process_turn(
    session_id,
    human_message="How does Python handle memory management?",
    agent_response="Python uses reference counting and a cyclic garbage collector...",
    timestamp=datetime.now(timezone.utc).isoformat(),
)

print(f"Fidelity:         {result.fidelity_score:.2f}")
print(f"Health:           {result.health_status}")
print(f"Circadian factor: {result.circadian_factor:.2f}")
print(f"Causal horizon:   {result.reachable_turns} reachable turns")
for event in result.events:
    print(f"  Event: {event.type} (confidence={event.confidence:.2f})")

Framework integrations

OpenAI SDK

from openai import OpenAI
from horizon_monitor import FidelityMonitor

monitor = FidelityMonitor()
session_id = monitor.new_conversation()
client = monitor.wrap(OpenAI(), session_id)

response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Tell me about quantum computing."}]
)

traj = monitor.get_trajectory(session_id)
print(f"Fidelity: {traj.current_fidelity:.2f}  T*: {traj.estimated_t_star}")

monitor.wrap() accepts custom timestamp and context providers for testing and replay.

Anthropic SDK

from anthropic import Anthropic
from horizon_monitor import FidelityMonitor

monitor = FidelityMonitor()
session_id = monitor.new_conversation()
client = monitor.wrap(Anthropic(), session_id)

response = client.messages.create(
    model="claude-3-5-sonnet-20241022",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Explain RLHF."}]
)

LangChain

from langchain_openai import ChatOpenAI
from horizon_monitor import FidelityMonitor
from horizon_monitor.integrations.langchain import HorizonCallback

monitor = FidelityMonitor()
session_id = monitor.new_conversation()
callback = HorizonCallback(monitor, session_id)

llm = ChatOpenAI(callbacks=[callback])
llm.invoke("Explain the CAP theorem.")
print(f"Fidelity: {callback.last_result.fidelity_score:.2f}")

OpenAI Agents SDK

from agents import Agent, Runner
from horizon_monitor import FidelityMonitor