Having .star file in directory breaks fizzbee

[GilbertBckr]

Hello everyone, great project!
I believe to have found a bug.
Let me know if you need any more clarification on my part :)

Description

When a .star file exists in the same directory as a .fizz specification, FizzBee attempts to parse the .star file and crashes with a parsing error, even when explicitly running fizz main.fizz.

I discovered this while trying to use a .star file to take advantage of Starlark language server features for development.

Expected Behavior

fizz main.fizz should only process main.fizz and ignore unrelated .star files in the directory, or at minimum provide a clear error message if .star files must follow specific syntax.

Actual Behavior

FizzBee automatically loads all .star files in the directory and crashes with a parsing error, preventing any specifications from running.

Steps to Reproduce

1. Create an empty directory and navigate to it
2. Create a main.fizz file with the following content:

   action Init:
     state = "init"
   
   action Next:
     state = "next"

3. Create any arbitrary .star file (e.g., test.star) with any content
4. Run fizz main.fizz

Error Output

Model checking main.json
configFileName: fizz.yaml
fizz.yaml not found. Using default options
StateSpaceOptions: options:{max_actions:100  max_concurrent_actions:2}
main.star
panic: main.star:1:12: got identifier, want newline

goroutine 1 [running]:
github.com/fizzbee-io/fizzbee/modelchecker.LoadModule({0x1400000e160, 0x9})
        modelchecker/processor.go:123 +0xa4
github.com/fizzbee-io/fizzbee/modelchecker.HandleModules({0x1025f8350?, 0x4?})
        modelchecker/processor.go:101 +0x11c
github.com/fizzbee-io/fizzbee/modelchecker.(*Processor).InitializeNode(0x14000290000)
        modelchecker/processor.go:1050 +0x8c
github.com/fizzbee-io/fizzbee/modelchecker.(*Processor).Start(0x14000290000)
        modelchecker/processor.go:1096 +0x4c
main.startModelChecker(0x14000290000)
        main.go:739 +0x8c
main.modelCheckSingleSpec(0x1400011c000, 0x14000181aa0, {0x1025f8350, 0x1}, {0x1400018e100, 0x1b}, {0x14000120830, 0x9}, 0x0)
        main.go:479 +0x274
main.main()
        main.go:75 +0x3a0

Environment

• OS: macOS Tahoe 26.2
• FizzBee version: 0.3.1 (installed via Homebrew)

Workaround

Remove all .star files from the working directory before running FizzBee specifications.

[jp-fizzbee]

@GilbertBckr Thanks for reporting this issue. I was working on a workaround to speed up and a way to allow using existing starlark files as is to make it easy. But couldn't fully complete and haven't figured out the right import syntax. That said, the presence of .star file shouldn't cause it to fail.
For me, this works.

utils.star

def double(x):
    return x * 2

Counter.fizz

---
deadlock_detection: false
---
# utils.star is auto-imported as `utils` namespace.

action Init:
    x = 0

atomic action Step:
    require x < 8
    x = utils.double(x) + 1

---

Is the .star file a valid file?
I want to disable auto import and do explicit imports. But a bit unsure whether to use python like syntax or starlark style.

python style

import filename
import filename as alias
# probably we could skip `from` clause 

starlark style load function

load("filename.star", "var1", "function1")  

If we support python style, there is also a difference when we want to support importing .fizz files. Should import filename look for filename.fizz or filename.star and if both are present, which one should take precedence.

For now, I am gravitating towards python style import, and look for .fizz first followed by .star.

Do you have any thoughts on this? As a temporary fix, I think I must also make sure if there is any parsing error with the auto-imported files, it should fail only when it is used.

[jp-fizzbee]

@GilbertBckr Merged a PR #327 to not fail if a star file lead to a parser error.