App runs when running `briefcase dev -r` but fails to install dependencies with `briefcase build -r`

[YHordijk]

Describe the bug

I have a bit of an annoying issue with my app. When I run briefcase dev -r all the requirements are properly updated, all the package versions are correct, and the app runs perfectly. As soon as I try to run briefcase build -r I suddenly run into issues related to installing some packages that were installed fine with briefcase dev -r:

ERROR: Ignored the following versions that require a different python version: 3.5 Requires-Python >=3.11; 3.5rc0 Requires-Python >=3.11
ERROR: Could not find a version that satisfies the requirement docx>=0.2.4 (from tcutility) (from versions: none)
ERROR: No matching distribution found for docx>=0.2.4

It is related to two packages (also mine) called TCutility and TCviewer for which I specify the required version to be 0.16.11 and 0.1.3 respectively. These versions both support Python==3.10. It seems that for some reason pip tries to find a Python>=3.11 version for some packages while I am using a Python==3.10 environment. I don't understand why all the packages install correctly in dev-mode and fail when building the app.

Steps to reproduce

1. In a new folder run python3 -m venv test-env
2. Activate the environment source test-env/bin/activate
3. Install briefcase python -m pip install briefcase
4. Create a new briefcase project briefcase new
5. Press enter on everything to setup a basic project
6. Add "tcutility>=0.16.11" to the requirements in the pyproject.toml under [tool.briefcase.app.helloworld.macOS]
7. Move into the folder and run the project in dev mode cd helloworld; briefcase dev -r
8. A screen opens, no errors in the log
9. Build the app: briefcase build -r and get the following error:

ERROR: No matching distribution found for docx>=0.2.4
Installing app requirements... errored

Expected behavior

I expect tcutility to be included in the App build.

Screenshots

No response

Environment

• Operating System: MacOS Sonoma 14.6.1 with ARM64
• Python version: 3.10
• Pip freeze after using dev-mode shows:

anyio==4.10.0
arrow==1.3.0
attrs==25.3.0
bcrypt==4.3.0
beautifulsoup4==4.13.5
binaryornot==0.4.4
briefcase==0.3.25
build==1.3.0
certifi==2025.8.3
cffi==2.0.0
chardet==5.2.0
charset-normalizer==3.4.3
click==8.2.1
contourpy==1.3.2
cookiecutter==2.6.0
cryptography==45.0.7
cycler==0.12.1
dictfunc==1.1.0
dill==0.4.0
dmgbuild==1.6.5
docx==0.2.4
ds-store==1.3.1
et_xmlfile==2.0.0
exceptiongroup==1.3.0
fonttools==4.59.2
gitdb==4.0.12
GitPython==3.1.45
h11==0.16.0
htmldocx==0.0.6
httpcore==1.0.9
httpx==0.28.1
idna==3.10
importlib_metadata==8.7.0
iniconfig==2.1.0
invoke==2.2.0
Jinja2==3.1.6
kiwisolver==1.4.9
listfunc==1.0.0
lxml==5.2.0
mac-alias==2.2.2
markdown-it-py==4.0.0
MarkupSafe==3.0.2
matplotlib==3.10.6
mdurl==0.1.2
numpy==2.2.6
opencv-python==4.12.0.88
openpyxl==3.1.5
packaging==25.0
pandas==2.3.2
paramiko==4.0.0
pillow==11.3.0
plams==2025.104
platformdirs==4.4.0
pluggy==1.6.0
psutil==7.0.0
pycparser==2.22
Pygments==2.19.2
PyNaCl==1.5.0
pyparsing==3.2.3
pyproject_hooks==1.2.0
pytest==8.4.2
python-dateutil==2.9.0.post0
python-docx==1.2.0
python-slugify==8.0.4
pytz==2025.2
PyYAML==6.0.2
requests==2.32.5
rich==14.1.0
rubicon-objc==0.5.2
scipy==1.15.3
six==1.17.0
smmap==5.0.2
sniffio==1.3.1
soupsieve==2.8
std-nslog==1.0.3
StrEnum==0.4.15
TCutility==0.16.11
text-unidecode==1.3
toga-cocoa==0.5.2
toga-core==0.5.2
tomli==2.2.1
tomli_w==1.2.0
travertino==0.5.2
truststore==0.10.4
types-python-dateutil==2.9.0.20250822
typing_extensions==4.15.0
tzdata==2025.2
urllib3==2.5.0
zipp==3.23.0

Logs

briefcase.2025_09_09-11_32_23.build.log

Additional context

No response