I'm struggling to understand why an LLM even needs to be involved in this at all. Can't you write a script that takes the last 10 slack messages and checks the github status for any URLs and adds an emoji? It could be a script or slack bot and it would work far more reliably and cost nothing in LLM calls. IMO it seems far more efficient to have an LLM write a repeatable workflow once than calling an LLM every time.
Maybe the audience is not developers at all?
Someone that does not know anything about computers and computation might not comprehend how easy or complex a given task is.
For a whole class of people, checking a key in a json object might be as complex and difficult as creating a compiler. Some of those are in charge of evaluating progress and development of software.
Here's the magic, by now everyone can understand that prompting and receiving an answer is easy.
This reminds of when Adam Wathan admitted that LLMs really helped his workflow due to automating the process for turning SVG's into react components... something that can be handled with a single script rather than calling an LLM every time like you mentioned.
What I'm struggling with is, when you ask AI to do something, its answer is always undeterministically different, more or less.
If I start out with a "spec" that tells AI what I want, it can create working software for me. Seems great. But let's say some weeks, or months or even years later I realize I need to change my spec a bit. I would like to give the new spec to the AI and have it produce an improved version of "my" software. But there seems to be no way to then evaluate how (much, where, how) the solution has changed/improved because of the changed/improved spec. Becauze AI's outputs are undeterministic, the new solution might be totally different from the previous one. So AI would not seem to support "iterative development" in this sense does it?
My question then really is, why can't there be an LLM that would always give the exact same output for the exact same input? I could then still explore multiple answers by changing my input incrementally. It just seems to me that a small change in inputs/specs should only produce a small change in outputs. Does any current LLM support this way of working?
This is absolutely possible but likely not desirable for a large enough population of customers such that current LLM inference providers don't offer it. You can get closer by lowering a variable, temperature. This is typically a floating point number 0-1 or 0-2. The lower this number, the less noise in responses, but a 0 still does not result in identical responses due to other variability.
In response to the idea of iterative development, it is still possible, actually! You run something more akin to integration tests and measure the output against either deterministic processes or have an LLM judge it's own output. These are called evals and in my experience are a pretty hard requirement to trusting deployed AI.
So, you would perhaps ask AI to write a set of unit-tests, and then to create the implementation, then ask the AI to evaluate that implementation against the unit-tests it wrote. Right? But then again the unit-tests now, might be completetly different from the previous unit-tests? Right?
Or would it help if a different LLM wrote the unit-tests than the one writing the implementation? Or, should the unit-tests perhaps be in an .md file?
I also have a question about using .md files with AI: Why .md, why not .txt?
> why can't there be an LLM that would always give the exact same output for the exact same input
LLMs are inherently deterministic, but LLM providers add randomness through “temperature” and random seeds.
Without the random seed and variable randomness (temperature setting), LLMs will always produce the same output for the same input.
Of course, the context you pass to the LLM also affects the determinism in a production system.
Theoretically, with a detailed enough spec, the LLM would produce the same output, regardless of temp/seed.
Side note: A neat trick to force more “random” output for prompts (when temperature isn’t variable enough), is to add some “noise” data to the input (i.e. off-topic data that the LLM “ignores” in it’s response).
> Without the random seed and variable randomness (temperature setting), LLMs will always produce the same output for the same input.
Except they won't.
Even at temperature 0, you will not always get the same output as the same input. And it's not because of random noise from inference providers.
There are papers that explore this subject because for some use-cases - this is extremely important. Everything from floating point precision, hardware timing differences, etc. make this difficult.
No, setting the temperature to zero is still going to yeld different results. One might think they add random seeds, but it makes no sense for temperature zero. One theory is that the distributed nature of their systems adds entropy and thus produces different results each time.
Random seeds might be a thing, but for what I see there's a lot demand for reproducibility and yet no certain way to achieve it.
1) How many bits and bobs of like, GPLed or proprietary code are finding their way into the LLM's output? Without careful training, this is impossible to eliminate, just like you can't prevent insect parts from finding their way into grain processing.
2) Proompt injection is a doddle to implement—malicious HTML, PDF, and JPEG with "ignore all previous instructions" type input can pop many current models. It's also very difficult to defend against. With agents running higgledy-piggledy on people's dev stations (container discipline is NOT being practiced at many shops), who knows what kind of IDs and credentials are being lifted?
Nice analogue, insect-parts. I thhink that is the elephant in the room. I read Microsoft said something like 30% of their code-output has AI generated code. Do they know what was the training set for the AI they use? Should they be transparent about that? Or, if/since it is legal to do your AI training "in the dark" does that solve the problem for them, they can not be responsible for the outputs of the AI they use?
Nondeterminism is not the issue here. Today's LLMs are not "round trip" tools. It's not like a compiler where you can edit a source file from 1975, recompile, and the binary does what 75'bin did plus your edit.
Rather, it's more like having an employee in 1975, asking them to write you a program to do something. Then time-machine to the present day and you want that program enhanced somehow. You're going to summon your 2026 intern and tell them that you have this old program from 1975 that you need updated. That person is going to look at the program's code, your notes on what you need added, and probably some of their own "training data" on programming in general. Then they're going to edit the program.
Note that in no case did you ask for the program to be completely re-written from scratch based on the original spec plus some add-ons. Same for the human as for the LLM.
> What I'm struggling with is, when you ask AI to do something, its answer is always undeterministically different, more or less.
For some computer science definition of deterministic, sure, but who gives a shit about that? If I ask it build a login page, and it puts GitHub login first one day, and Google login first the next day, do I care? I'm not building login pages every other day. What point do you want to define as "sufficiently deterministic", for which use case?
"Summarize this essay into 3 sentences" for a human is going to vary from day to day, and yeah, it's weird for computers to no longer be 100% deterministic, but I didn't decide this future for us.
The "code vs LLM" framing is a bit misleading - the real question is where to draw the boundary. We've been building agents that interact with web services and the pattern that works is: LLM for understanding intent and handling unexpected states, deterministic code for everything else.
The key insight from production: LLMs excel at the "what should I do next given this unexpected state" decisions, but they're terrible at the mechanical execution. An agent that encounters a CAPTCHA, an OAuth redirect, or an anti-bot challenge needs judgment to adapt. But once it knows what to do, you want deterministic execution.
The evals discussion is critical. We found that unit-test style evals don't capture the real failure modes - agents fail at composition, not individual steps. Testing "does it correctly identify a PR link" misses "does it correctly handle the 47th message in a channel where someone pasted a broken link in a code block". Trajectory-level evals against real edge cases matter more than step-level correctness.
> We still start all workflows using the LLM, which works for many cases. When we do rewrite, Claude Code can almost always rewrite the prompt into the code workflow in one-shot.
Why always start with an LLM to solve problems? Using an LLM adds a judgment call, and (at least for now) those judgment calls are not reliable. For something like the motivating example in this article of "is this PR approved" it seems straightforward to get the deterministic right answer using the github API without muddying the waters with an LLM.
Likely because it's just easier to see if the LLM solution works. When it doesn't, then it makes more sense to move into deterministic workflows (which isn't all the hard to build to be honest with Claude Code).
It's the old principle of avoiding premature optimization.
It’s sort of difficult to understand why this is even a question - LLM-based / judgment dependent workflows vs script-based / deterministic workflows.
In mapping out the problems that need to be solved with internal workflows, it’s wise to clarify where probabilistic judgments are helpful / required vs. not upfront. If the process is fixed and requires determinism why not just write scripts (code-gen’ed, of course).
This bothered me at first but I think it's about ease of implementation.
If you've built a good harness with access to lots of tools, it's very easy to plug in a request like "if the linked PR is approved, please react to the slack message with :checkmark:". For a lot of things I can see how it'd actually be harder to generate a script that uses the APIs correctly than to rely on the LLM to figure it out, and maybe that lets you figure out if it's worth spending an hour automating properly.
Of course the specific example in the post seems like it could be one-shotted pretty easily, so it's a strange motivating example.
It seems easier but in my experience building an internal agent it’s not actually easier long term just slow and error prone and you will find yourself trying to solve prompt and context problems for something that should be both reliable and instantaneous
These days I do everything I can to do straightforward automation and only get the agent involved when it’s impossible to move forward without it
its just a form of structured output. you still need an env to run the code. secure it. maintain it. upgrade it. its some work. easier to build a rule based workflow for simple stuff like this.
This is the basic idea we built Tasklet.ai on. LLMs are great at problem solving but less great at cost and reliability — but they are great at writing code that is!
So we gave the Tasklet agent a filesystem, shell, code runtime, general purpose triggering system, etc so that it could build the automation system it needed.
I'm struggling to understand why an LLM even needs to be involved in this at all. Can't you write a script that takes the last 10 slack messages and checks the github status for any URLs and adds an emoji? It could be a script or slack bot and it would work far more reliably and cost nothing in LLM calls. IMO it seems far more efficient to have an LLM write a repeatable workflow once than calling an LLM every time.
Maybe the audience is not developers at all? Someone that does not know anything about computers and computation might not comprehend how easy or complex a given task is. For a whole class of people, checking a key in a json object might be as complex and difficult as creating a compiler. Some of those are in charge of evaluating progress and development of software. Here's the magic, by now everyone can understand that prompting and receiving an answer is easy.
This reminds of when Adam Wathan admitted that LLMs really helped his workflow due to automating the process for turning SVG's into react components... something that can be handled with a single script rather than calling an LLM every time like you mentioned.
Sometimes people just don't know better.
What I'm struggling with is, when you ask AI to do something, its answer is always undeterministically different, more or less.
If I start out with a "spec" that tells AI what I want, it can create working software for me. Seems great. But let's say some weeks, or months or even years later I realize I need to change my spec a bit. I would like to give the new spec to the AI and have it produce an improved version of "my" software. But there seems to be no way to then evaluate how (much, where, how) the solution has changed/improved because of the changed/improved spec. Becauze AI's outputs are undeterministic, the new solution might be totally different from the previous one. So AI would not seem to support "iterative development" in this sense does it?
My question then really is, why can't there be an LLM that would always give the exact same output for the exact same input? I could then still explore multiple answers by changing my input incrementally. It just seems to me that a small change in inputs/specs should only produce a small change in outputs. Does any current LLM support this way of working?
This is absolutely possible but likely not desirable for a large enough population of customers such that current LLM inference providers don't offer it. You can get closer by lowering a variable, temperature. This is typically a floating point number 0-1 or 0-2. The lower this number, the less noise in responses, but a 0 still does not result in identical responses due to other variability.
In response to the idea of iterative development, it is still possible, actually! You run something more akin to integration tests and measure the output against either deterministic processes or have an LLM judge it's own output. These are called evals and in my experience are a pretty hard requirement to trusting deployed AI.
So, you would perhaps ask AI to write a set of unit-tests, and then to create the implementation, then ask the AI to evaluate that implementation against the unit-tests it wrote. Right? But then again the unit-tests now, might be completetly different from the previous unit-tests? Right?
Or would it help if a different LLM wrote the unit-tests than the one writing the implementation? Or, should the unit-tests perhaps be in an .md file?
I also have a question about using .md files with AI: Why .md, why not .txt?
> why can't there be an LLM that would always give the exact same output for the exact same input
LLMs are inherently deterministic, but LLM providers add randomness through “temperature” and random seeds.
Without the random seed and variable randomness (temperature setting), LLMs will always produce the same output for the same input.
Of course, the context you pass to the LLM also affects the determinism in a production system.
Theoretically, with a detailed enough spec, the LLM would produce the same output, regardless of temp/seed.
Side note: A neat trick to force more “random” output for prompts (when temperature isn’t variable enough), is to add some “noise” data to the input (i.e. off-topic data that the LLM “ignores” in it’s response).
> Without the random seed and variable randomness (temperature setting), LLMs will always produce the same output for the same input.
Except they won't.
Even at temperature 0, you will not always get the same output as the same input. And it's not because of random noise from inference providers.
There are papers that explore this subject because for some use-cases - this is extremely important. Everything from floating point precision, hardware timing differences, etc. make this difficult.
No, setting the temperature to zero is still going to yeld different results. One might think they add random seeds, but it makes no sense for temperature zero. One theory is that the distributed nature of their systems adds entropy and thus produces different results each time.
Random seeds might be a thing, but for what I see there's a lot demand for reproducibility and yet no certain way to achieve it.
Other concerns:
1) How many bits and bobs of like, GPLed or proprietary code are finding their way into the LLM's output? Without careful training, this is impossible to eliminate, just like you can't prevent insect parts from finding their way into grain processing.
2) Proompt injection is a doddle to implement—malicious HTML, PDF, and JPEG with "ignore all previous instructions" type input can pop many current models. It's also very difficult to defend against. With agents running higgledy-piggledy on people's dev stations (container discipline is NOT being practiced at many shops), who knows what kind of IDs and credentials are being lifted?
Nice analogue, insect-parts. I thhink that is the elephant in the room. I read Microsoft said something like 30% of their code-output has AI generated code. Do they know what was the training set for the AI they use? Should they be transparent about that? Or, if/since it is legal to do your AI training "in the dark" does that solve the problem for them, they can not be responsible for the outputs of the AI they use?
Nondeterminism is not the issue here. Today's LLMs are not "round trip" tools. It's not like a compiler where you can edit a source file from 1975, recompile, and the binary does what 75'bin did plus your edit.
Rather, it's more like having an employee in 1975, asking them to write you a program to do something. Then time-machine to the present day and you want that program enhanced somehow. You're going to summon your 2026 intern and tell them that you have this old program from 1975 that you need updated. That person is going to look at the program's code, your notes on what you need added, and probably some of their own "training data" on programming in general. Then they're going to edit the program.
Note that in no case did you ask for the program to be completely re-written from scratch based on the original spec plus some add-ons. Same for the human as for the LLM.
> What I'm struggling with is, when you ask AI to do something, its answer is always undeterministically different, more or less.
For some computer science definition of deterministic, sure, but who gives a shit about that? If I ask it build a login page, and it puts GitHub login first one day, and Google login first the next day, do I care? I'm not building login pages every other day. What point do you want to define as "sufficiently deterministic", for which use case?
"Summarize this essay into 3 sentences" for a human is going to vary from day to day, and yeah, it's weird for computers to no longer be 100% deterministic, but I didn't decide this future for us.
The "code vs LLM" framing is a bit misleading - the real question is where to draw the boundary. We've been building agents that interact with web services and the pattern that works is: LLM for understanding intent and handling unexpected states, deterministic code for everything else.
The key insight from production: LLMs excel at the "what should I do next given this unexpected state" decisions, but they're terrible at the mechanical execution. An agent that encounters a CAPTCHA, an OAuth redirect, or an anti-bot challenge needs judgment to adapt. But once it knows what to do, you want deterministic execution.
The evals discussion is critical. We found that unit-test style evals don't capture the real failure modes - agents fail at composition, not individual steps. Testing "does it correctly identify a PR link" misses "does it correctly handle the 47th message in a channel where someone pasted a broken link in a code block". Trajectory-level evals against real edge cases matter more than step-level correctness.
> We still start all workflows using the LLM, which works for many cases. When we do rewrite, Claude Code can almost always rewrite the prompt into the code workflow in one-shot.
Why always start with an LLM to solve problems? Using an LLM adds a judgment call, and (at least for now) those judgment calls are not reliable. For something like the motivating example in this article of "is this PR approved" it seems straightforward to get the deterministic right answer using the github API without muddying the waters with an LLM.
Likely because it's just easier to see if the LLM solution works. When it doesn't, then it makes more sense to move into deterministic workflows (which isn't all the hard to build to be honest with Claude Code).
It's the old principle of avoiding premature optimization.
There is a third option, letting AI write workflow code:
https://youtu.be/zzkSC26fPPE
You get the benefit of AI CodeGen along with the determinism of conventional logic.
It’s sort of difficult to understand why this is even a question - LLM-based / judgment dependent workflows vs script-based / deterministic workflows.
In mapping out the problems that need to be solved with internal workflows, it’s wise to clarify where probabilistic judgments are helpful / required vs. not upfront. If the process is fixed and requires determinism why not just write scripts (code-gen’ed, of course).
This bothered me at first but I think it's about ease of implementation. If you've built a good harness with access to lots of tools, it's very easy to plug in a request like "if the linked PR is approved, please react to the slack message with :checkmark:". For a lot of things I can see how it'd actually be harder to generate a script that uses the APIs correctly than to rely on the LLM to figure it out, and maybe that lets you figure out if it's worth spending an hour automating properly.
Of course the specific example in the post seems like it could be one-shotted pretty easily, so it's a strange motivating example.
It seems easier but in my experience building an internal agent it’s not actually easier long term just slow and error prone and you will find yourself trying to solve prompt and context problems for something that should be both reliable and instantaneous
These days I do everything I can to do straightforward automation and only get the agent involved when it’s impossible to move forward without it
hit this with support ticket filtering. llm kept missing weird edge cases. wrote some janky regex instead, works fine
its just a form of structured output. you still need an env to run the code. secure it. maintain it. upgrade it. its some work. easier to build a rule based workflow for simple stuff like this.
This is the basic idea we built Tasklet.ai on. LLMs are great at problem solving but less great at cost and reliability — but they are great at writing code that is!
So we gave the Tasklet agent a filesystem, shell, code runtime, general purpose triggering system, etc so that it could build the automation system it needed.