Project isn't updated to the directory set by "directory" argument

Description

I am not sure if it is, but it looks like a bug, when I run poetry --directory path/to/project build I get an error:

WARNING: No build backend defined. Please define one in the pyproject.toml.
...

(backend is set under "path/to/project/pyproject.toml")

...
Readme path path/to/project/README.md does not exist.

It's weird because if I run Poetry from said directory by changing directory on shell it does work correctly without any issues: poetry build.

Maybe my understanding about this is wrong.

Workarounds

1. Changing directory to project manually and running build works: cd path/to/project && poetry build
2. Appending --project ./ seems to work as well. This is weird, I'd assume project is automatically set to "currect directory" when it is changed with --directory but it's not. So you have to manually switch it by doing something like this:

poetry --directory path/to/project --project ./ build

which seems to work correctly as well.

Poetry Installation Method

pip

Operating System

RHEL9

Poetry Version

2.1.1

Poetry Configuration

Fully vanilla config, only changes are source repositories which are PyPi mirrors.

Python Sysconfig

No response

Example pyproject.toml

[tool.poetry]
name = "poetry-demo"
version = "0.1.0"
description = ""
authors = ["My name", "email@example.net"]
readme = "README.md"
package-mode = true
packages = [
  { include = "src" }
]

[tool.poetry.dependencies]
python = "^3.9"
boto3 = "^1.35.54"
poethepoet = "^0.33.0"
requests = "^2.32.3"

[[tool.poetry.source]]
name = "nexus"
url = "https://nexus.net/repo/repository/pypi/simple/"
priority = "primary"

[tool.poetry.group.dev.dependencies]
nox = "^2024.10.9"
poethepoet = "^0.33.0"
pytest = "^8.3.5"
nox-poetry = "^1.2.0"

[tool.poetry.requires-plugins]
poetry-plugin-export = ">=1.8"

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

Poetry Runtime Logs

Sorry, I can't get these right now, let me know if these are mandatory.

Start by reproducing poetry --directory path/to/project build and compare it with the working cd path/to/project && poetry build and --project ./ variant. Inspect how the command resolves path/to/project/pyproject.toml and README.md; done means the build uses the target project's configuration without requiring --project ./.