fix: remove backend-path to resolve ValueError: paths must be inside … (#231)

* fix: remove backend-path to resolve ValueError: paths must be inside source tree

python -m build fails in CI with:
  ValueError: paths must be inside source tree

This is thrown by pyproject_hooks.BuildBackendHookCaller.__init__ which
validates that all backend-path entries resolve inside the package source
directory. The backend-path = ["../../versioning/helper"] in each package's
pyproject.toml points outside the package tree, triggering this check before
any build code runs. Setting PYTHONPATH has no effect since the error fires
during path validation, not import.

Fix: remove backend-path from all 14 packages. The CI pipeline already exports
PYTHONPATH="${ROOT_DIR}/versioning/helper" which makes build_backend importable
in the hook subprocess. The custom backend and its S360 version constraint
injection are unaffected. uv build from the repo root continues to work for
local development.

* Set PYTHONPATH for install step in CI workflow

Added PYTHONPATH environment variable pointing to versioning/helper during the "Install the project" step in the CI workflow. This ensures Python can locate necessary modules during installation.

* fix: set PYTHONPATH at job level so all steps can import build_backend

Step-level env only applies to a single step. uv sync passed but uv build
and tox steps still failed with ModuleNotFoundError: No module named build_backend.

Moving PYTHONPATH to job-level env ensures it is available for all steps:
uv sync, uv build, tox, and any future steps that invoke the build backend.

Also fix docstring example in build_backend.py to include packaging in
build-system.requires, matching what the packages actually declare.

---------

Co-authored-by: Grant Harris <96964444+gwharris7@users.noreply.github.com>

Author: sellakumaran

.github/workflows/ci.yml

@@ -85,6 +85,8 @@ jobs:
     defaults:
       run:
         working-directory: ./
+    env:
+      PYTHONPATH: ${{ github.workspace }}/versioning/helper
 
     strategy:
       matrix:

libraries/microsoft-agents-a365-notifications/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-notifications"

libraries/microsoft-agents-a365-observability-core/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-core"

libraries/microsoft-agents-a365-observability-extensions-agentframework/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-extensions-agent-framework"

libraries/microsoft-agents-a365-observability-extensions-langchain/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-extensions-langchain"

libraries/microsoft-agents-a365-observability-extensions-openai/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-extensions-openai"

libraries/microsoft-agents-a365-observability-extensions-semantickernel/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-extensions-semantic-kernel"

libraries/microsoft-agents-a365-observability-hosting/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-observability-hosting"

libraries/microsoft-agents-a365-runtime/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-runtime"

libraries/microsoft-agents-a365-tooling-extensions-agentframework/pyproject.toml

@@ -1,7 +1,6 @@
 [build-system]
 requires = ["setuptools>=68", "wheel", "tzdata", "tomlkit", "packaging"]
 build-backend = "build_backend"
-backend-path = ["../../versioning/helper"]
 
 [project]
 name = "microsoft-agents-a365-tooling-extensions-agentframework"