# Giving AI Agents a Deterministic Clock (Zero LLM in the Loop)

> Source: <https://dev.to/jservodotcom/giving-ai-agents-a-deterministic-clock-zero-llm-in-the-loop-3fk5>
> Published: 2026-08-29 19:50:18+00:00

When building autonomous AI systems, developers eventually hit a fundamental architectural wall. Your coding agent asks you a question, and you step away from the keyboard. Today, nothing happens. The session hangs, the question rots, and the work stalls.

At [J. Servo LLC](https://jservo.com), we architect enterprise AI systems to operate predictably. We built [Sundial](https://github.com/bigjoe-oti/sundial) to act as the missing half of the human-in-the-loop framework[cite: 1]. It operates on a single defining principle: Sundial measures absence, not time[cite: 1].

When the human becomes the blocker, the agent's clock keeps running[cite: 1]. It nudges you on your desktop, escalates politely through your absence, and greets you with continuity upon your return[cite: 1]. If you never answer, the agent proceeds on its stated judgment or stands down[cite: 1]. It does this deterministically, with zero model calls, and runs 100% locally[cite: 1].

Relying on a Large Language Model to determine if a user has abandoned a session violates lean architecture principles. Time tracking belongs at the system level. The separation of actors is the design[cite: 2].

Sundial enforces a strict architectural boundary across three main components:

`HIDIdleTime`

, `lsappinfo`

, and `pmset`

on macOS, and `xprintidle`

or `loginctl`

on Linux[cite: 1]. Any missing sensor returns `None`

and softens to wall time rather than blocking the system[cite: 1].`launchd`

that handles presence classification and escalation[cite: 1, 2]. It uses zero LLMs[cite: 2].`data/`

directory[cite: 2]. State is written atomically using `NamedTemporaryFile`

, `fsync()`

, and `os.replace()`

, serialized by inter-process locking via `fcntl.flock`

[cite: 1]. Escalation advances only while you genuinely have not seen the chat[cite: 1]. Sundial categorizes your presence into three strict states:

The system enforces urgency tiers[cite: 1]. A high-urgency task utilizes a retimed ladder of 5, 10, and 20 minutes, backed by a hard 40-minute wall ceiling that forces a final resolution regardless of sensor data[cite: 1].

A ripe nudge never fires mid-keystroke[cite: 1]. Drawing from Interruption Science, the daemon holds ripe notifications for up to three minutes waiting for a natural typing gap or application switch before delivering[cite: 1].

Sound courtesy is strictly enforced. Chimes escalate with urgency, but they mute unconditionally if your screen is locked or if you have been away for more than 30 minutes[cite: 1].

Agents must stop guessing execution durations using fabricated calendar weeks[cite: 1]. Sundial tracks the empirical ratio distribution of actual versus estimated time across completed tasks[cite: 1].

The estimation engine (`lib/estimator.py`

) operates purely mathematically to compute empirical P50 and P90 execution durations[cite: 1]. It applies a small-n honesty floor, utilizing a 2.0x multiplier when sample sizes are below five, ensuring the system never provides confident numbers from thin data[cite: 1, 2].

The trigger path never thinks[cite: 2]. When an agent blocks on an `awaiting-reply`

question, the ladder climbs until expiry, triggering the Autonomy Gate in `lib/policy.py`

[cite: 1].

The agent is forced into a deterministic verdict:

The absolute autonomy rule: Silence-while-present is an answer, whereas silence-while-absent is a void[cite: 1]. They receive distinct, deterministic responses[cite: 1].

Sundial integrates via a generic hook protocol passing JSON on `stdin`

and outputting text blocks to `stdout`

[cite: 1]. It supports ready-made adapters for `claude-code`

, `hermes`

, and generic environments[cite: 1].

```
bash
# Clone the repository
git clone [https://github.com/bigjoe-oti/sundial.git](https://github.com/bigjoe-oti/sundial.git) ~/sundial
cd ~/sundial

# Run the installer for your target platform
./setup.sh --name "YourName" --fresh

Built with obsession by Yousef Ali and the engineering team at J. Servo LLC.
```