template: `dora new --lang python` projects fail `uv run pytest` with ModuleNotFoundError

[heyong4725]

Summary

dora new --lang python generates a project where uv run pytest from the project root fails with ModuleNotFoundError for every node package. This is the same root cause as the cli-python CI failure being patched in #1843, but the CI fix is intentionally scoped to "unblock the merge queue" rather than fixing the underlying template. Filing this so the template-level fix doesn't get lost.

Reproduction

On a clean checkout (after #1843 lands or with the CI fix patched locally is irrelevant — the issue is in the generated project):

dora new my_project --lang python
cd my_project
dora build dataflow.yml --uv
uv run pytest

Result:

FAILED listener-1/tests/test_listener_1.py::test_import_main
  > from listener_1.main import main
  E ModuleNotFoundError: No module named 'listener_1'
FAILED talker-1/tests/test_talker_1.py::test_import_main
  > from talker_1.main import main
  E ModuleNotFoundError: No module named 'talker_1'
FAILED talker-2/tests/test_talker_2.py::test_import_main
  > from talker_2.main import main
  E ModuleNotFoundError: No module named 'talker_2'
3 failed, 3 passed

Root cause

PR #1820 ("feat(uv): per-node managed Python venvs at build + runtime") changed dora build --uv to install each node's package into an isolated venv at .dora/python-envs/<node>/. The test stubs generated by the template at binaries/cli/src/template/python/__node-name__/tests/test___node_name__.py:11 do:

from __node_name__.main import main

uv run pytest at the project root resolves against the ambient venv, which doesn't have the per-node packages (they're in the isolated venvs). The generated project has no root pyproject.toml to give uv a way to install them.

Pre-#1820, dora build installed nodes into whatever venv was active, so this Just Worked.

How #1843 patches it for CI

.circleci/config.yml explicitly installs the three known template nodes into the active venv before uv run pytest:

uv pip install -e listener-1 -e talker-1 -e talker-2
uv run pytest

That fixes the CI smoke but doesn't help users who run dora new themselves. They hit the same error and have no obvious way to recover from the failure message.

Proposed approaches (pick one)

1. Root pyproject.toml in the generated project, with path-deps on each node. Makes uv sync install everything; uv run pytest then resolves all node packages. Closest to "user expectations for a Python project." Requires teaching dora new --lang python to emit a root pyproject.toml listing the generated nodes as dependencies ({ path = "./talker-1", editable = true } etc.).

2. Generated README that documents the test workflow. Add a "Testing" section to binaries/cli/src/template/python/README.md that says: "Before running uv run pytest, install each node into the active venv with uv pip install -e <node>/." Lower-effort, but punishes users who skim docs.

3. Run pytest inside each per-node venv. Architecturally cleanest (tests run in the same env as the node) but requires a wrapper script and changes the pytest UX. Probably overkill for the template.

4. A generated Makefile or shell script that handles dora build + per-node install + pytest in one command. Avoids the bare uv run pytest UX entirely.

My pick would be (1) — a root pyproject.toml is the path of least surprise for anyone arriving from the broader Python ecosystem, and uv is already a hard dep for the template's build flow.

Scope

This is a dora new --lang python template concern, in binaries/cli/src/template/python/. Not blocked by anything; #1843 unblocks CI separately. Could be picked up as a good-first-issue.