Field Notes
Reasoning vs Execution: Where AI Actually Fits in Automation
Durable automation systems separate AI-driven interpretation from deterministic execution instead of treating models as the entire workflow engine.
For the past couple of years, I’ve noticed a repeating pattern across teams building AI-powered workflows.
Someone identifies a manual process that should be automated.
The first instinct is almost always:
Input → AI Model → Output
The specific implementation varies, but the model sits at the center of the workflow.
At first, it feels magical. The demo works. It appears flexible. The possibilities seem endless.
Then reality starts to set in...
The workflow becomes slow. Outputs become unreliable. Edge cases pile up. Nobody fully understands why certain failures happen. The prompt grows from 20 lines to 400. Eventually, the system becomes harder to maintain than the original process it was supposed to replace.
This isn’t because AI is bad, it’s that we’re often using AI for the wrong parts of the system. The most reliable automation systems I’ve seen don’t treat AI as the entire workflow engine. They separate reasoning from execution.
The Core Mistake: Using AI to Hide Broken Processes
One of the biggest traps in AI automation is using models as a band-aid for operational problems that already existed. Often the real problem is that the process isn’t well defined and the underlying data isn’t trustworthy.
Instead of fixing the underlying process, teams wrap it in a prompt.
The system may initially appear more intelligent, but often it’s just obscuring complexity instead of removing it.
This creates what I’d call fuzzy infrastructure: systems that become increasingly difficult to reason about, test, and scale over time.
A deterministic system failing usually produces a reproducible bug whereas an AI-driven system failing often degrades unpredictably: inconsistent outputs, edge-case hallucinations, and confidence without reliability.
That difference becomes painfully obvious in production environments.
AI Is Excellent at Interpretation
The important nuance is that AI is incredibly valuable in automation systems, just not always where people first apply it.
AI excels at interpretation: extracting structure from messy inputs, identifying intent, summarizing information, and filling gaps humans would normally reason through.
In other words, AI is strongest where ambiguity genuinely exists.
But many workflows don’t actually contain much ambiguity.
Many enterprise workflows are fundamentally about state management, validation, orchestration, and enforcing business rules. Traditional software engineering is still the better tool for these problems.
The dangerous pattern looks like this:
Entire workflow → AI black box
More durable patterns look like this:
Messy input → AI interpretation → deterministic execution pipeline
OR
Structured input → deterministic execution pipeline
That distinction may seem subtle, but it completely changes the reliability of the system.
Deterministic Systems Compound Over Time
One reason traditional automation ages better is because deterministic systems compound operationally. They become easier to reason about, debug, and scale because the rules remain explicit and failures reproducible.
Meanwhile, many AI-first workflows accumulate hidden complexity over time. Larger prompts, undocumented business logic, model-specific behavior. Ironically, some “AI automations” end up recreating the same problems legacy systems had, just with less observability.
That doesn’t mean AI isn’t worth using. AI excels at interpretation of truly ambiguous data, summarization, and increasingly reasoning over information. But if the workflow already has structured inputs, stable requirements, and deterministic outputs, traditional software is often the better tool.
Before applying AI to every problem you face, ask yourself “Do I understand the workflow clearly? Could I design it better to automate using traditional methods? Is there actually ambiguity involved that justifies using AI?”
Backtesting and Evaluation Matter More Than Ever
Another issue I see constantly is teams treating AI workflows as inherently difficult to test or treating evaluation frameworks as an afterthought. In my experience, AI systems require more testing discipline, not less. Without proper evaluation, new prompts, tools, and models are added into a black box system with no way to understand if the system is actually improving with each change.
One of the best uses of AI, ironically, is helping engineers rapidly build and iterate deterministic systems that can actually be tested rigorously.
That’s increasingly become my preferred workflow:
- Use AI to accelerate development
- Use AI to identify edge cases
- Use AI to interpret unstructured inputs
- Use deterministic systems for execution
- Escalate uncertain cases to humans
This tends to produce systems that are both flexible and reliable.
A Practical Framework
Use deterministic systems when:
Rules are explicit, outputs must be auditable, and failures are expensive.
Use AI when:
Inputs are unstructured, ambiguity is unavoidable, and human-like interpretation is required.
Use hybrid systems when:
AI can interpret or normalize inputs before deterministic systems execute the workflow reliably.
In practice, the hybrid model is where I think most durable automation systems will land.
The Real Opportunity
AI should help systems understand. Deterministic infrastructure should help systems reliably act.
The future of automation probably isn’t fully deterministic systems or fully autonomous AI agents. It’s systems that clearly separate reasoning from execution.