Summary

Add the ability for rhiza to control selected fields in a downstream project's pyproject.toml via a new pyproject: section in .rhiza/template.yml. This is implemented entirely within rhiza (no rhiza-cli changes needed) using a Python utility script and a new make sync-pyproject target.

Background

Currently, pyproject.toml is completely excluded from rhiza's sync system — it is project-owned. However, several fields are naturally "rhiza-owned" and drift across downstream projects:

• requires-python — should match rhiza's supported Python version matrix
• classifiers — Python version classifiers should mirror .python-version / requires-python
• [tool.*] sections like [tool.deptry.package_module_name_map] — currently duplicated manually

The idea: extend .rhiza/template.yml with an optional pyproject: section. A new make sync-pyproject target reads it and non-destructively patches pyproject.toml, preserving all project-specific fields (name, version, description, authors, dependencies, etc.).

Changes Required

1. New utility script: .rhiza/utils/sync_pyproject.py

A Python script (stdlib only — no tomlkit dep needed for the basic patch, uses tomllib to read and string-based TOML writing to patch) that:

• Reads .rhiza/template.yml (using pyyaml, already a dev dep) and extracts the pyproject: section
• Reads the existing pyproject.toml
• Applies a non-destructive patch: only sets/replaces keys declared in the pyproject: section; never touches anything else
• Writes back the updated pyproject.toml preserving structure as much as possible
• Supports --dry-run flag to preview changes without writing
• Supports --check flag (exits non-zero if changes would be made, for CI)
• Prints a human-readable diff of what changed

The script should use tomlkit (which preserves comments and formatting) as the TOML write backend. Add tomlkit>=0.13,<1.0 to pyproject.toml's [dependency-groups].dev and to .rhiza/requirements/tools.txt.

Supported pyproject: keys in template.yml:

• requires-python — sets [project].requires-python
• classifiers — replaces [project].classifiers entirely (it's a list rhiza owns)
• tool-sections — a list of dotted TOML paths (e.g. tool.deptry.package_module_name_map) that are synced wholesale from rhiza's own pyproject.toml into the downstream project's pyproject.toml

The script must:

• Never touch name, version, description, authors, keywords, dependencies, [dependency-groups], [project.urls] unless explicitly listed
• Print [INFO] No pyproject: section in template.yml, nothing to do. and exit 0 if the section is absent (graceful no-op)
• Print [INFO] pyproject.toml is already up to date. if no changes are needed
• Be callable standalone: uv run python .rhiza/utils/sync_pyproject.py [--dry-run] [--check]

2. New Makefile target in .rhiza/make.d/releasing.mk

Add a sync-pyproject target:

sync-pyproject: ## sync pyproject.toml fields from .rhiza/template.yml (supports DRY_RUN=1, CHECK=1)
	@if [ -f "pyproject.toml" ] && [ -f ".rhiza/template.yml" ]; then \
		$(MAKE) install; \
		_FLAGS=""; \
		if [ -n "$(DRY_RUN)" ]; then _FLAGS="$$_FLAGS --dry-run"; fi; \
		if [ -n "$(CHECK)" ]; then _FLAGS="$$_FLAGS --check"; fi; \
		${UV_BIN} run python .rhiza/utils/sync_pyproject.py $$_FLAGS; \
	else \
		printf "${YELLOW}[WARN] pyproject.toml or .rhiza/template.yml not found, skipping sync-pyproject${RESET}\n"; \
	fi

Add sync-pyproject to the .PHONY list in releasing.mk.

3. Update rhiza's own .rhiza/template.yml (create it — it doesn't exist in the repo itself)

Wait — rhiza skips sync on itself (the make sync target checks for jebel-quant/rhiza remote and skips). The .rhiza/template.yml file doesn't exist in the repo itself by design. Instead, add a well-documented example as .rhiza/docs/TEMPLATE_YML_EXAMPLE.md showing the new pyproject: section.

4. Update .rhiza/template-bundles.yml

Add .rhiza/utils/sync_pyproject.py to the core bundle's files list (so it syncs to all downstream projects):

      - .rhiza/utils/sync_pyproject.py

5. Update pyproject.toml in rhiza itself

Add tomlkit to [dependency-groups].dev:

"tomlkit>=0.13,<1.0",  # TOML read/write with comment preservation for sync_pyproject.py

Also add it to [tool.deptry.package_module_name_map]:

tomlkit = "tomlkit"

6. Update .rhiza/requirements/tools.txt

Add:

tomlkit>=0.13,<1.0

7. New test file: .rhiza/tests/deps/test_sync_pyproject.py

Add tests that verify:

• sync_pyproject.py exists and is importable / syntax-valid
• It is a no-op when pyproject: section is absent from template.yml
• It correctly patches requires-python when specified
• It correctly replaces classifiers when specified
• It leaves name, version, description, `dependenc...