30 KiB
Agent Harness: GUI-to-CLI for Open Source Software
Purpose
This harness provides a standard operating procedure (SOP) and toolkit for coding agents (Claude Code, Codex, etc.) to build powerful, stateful CLI interfaces for open-source GUI applications. The goal: let AI agents operate software that was designed for humans, without needing a display or mouse.
General SOP: Turning Any GUI App into an Agent-Usable CLI
Phase 1: Codebase Analysis
- Identify the backend engine — Most GUI apps separate presentation from logic. Find the core library/framework (e.g., MLT for Shotcut, ImageMagick for GIMP).
- Map GUI actions to API calls — Every button click, drag, and menu item corresponds to a function call. Catalog these mappings.
- Identify the data model — What file formats does it use? How is project state represented? (XML, JSON, binary, database?)
- Find existing CLI tools — Many backends ship their own CLI (
melt,ffmpeg,convert). These are building blocks. - Catalog the command/undo system — If the app has undo/redo, it likely uses a command pattern. These commands are your CLI operations.
Phase 2: CLI Architecture Design
-
Choose the interaction model:
- Stateful REPL for interactive sessions (agents that maintain context)
- Subcommand CLI for one-shot operations (scripting, pipelines)
- Both (recommended) — a CLI that works in both modes
-
Define command groups matching the app's logical domains:
- Project management (new, open, save, close)
- Core operations (the app's primary purpose)
- Import/Export (file I/O, format conversion)
- Configuration (settings, preferences, profiles)
- Session/State management (undo, redo, history, status)
-
Design the state model:
- What must persist between commands? (open project, cursor position, selection)
- Where is state stored? (in-memory for REPL, file-based for CLI)
- How does state serialize? (JSON session files)
-
Plan the output format:
- Human-readable (tables, colors) for interactive use
- Machine-readable (JSON) for agent consumption
- Both, controlled by
--jsonflag
Phase 3: Implementation
- Start with the data layer — XML/JSON manipulation of project files
- Add probe/info commands — Let agents inspect before they modify
- Add mutation commands — One command per logical operation
- Add the backend integration — A
utils/<software>_backend.pymodule that wraps the real software's CLI. This module handles:- Finding the software executable (
shutil.which()) - Invoking it with proper arguments (
subprocess.run()) - Error handling with clear install instructions if not found
- Example (LibreOffice):
# utils/lo_backend.py def convert_odf_to(odf_path, output_format, output_path=None, overwrite=False): lo = find_libreoffice() # raises RuntimeError with install instructions subprocess.run([lo, "--headless", "--convert-to", output_format, ...]) return {"output": final_path, "format": output_format, "method": "libreoffice-headless"}
- Finding the software executable (
- Add rendering/export — The export pipeline calls the backend module. Generate valid intermediate files, then invoke the real software for conversion.
- Add session management — State persistence, undo/redo
- Add the REPL with unified skin — Interactive mode wrapping the subcommands.
- Copy
repl_skin.pyfrom the plugin (cli-anything-plugin/repl_skin.py) intoutils/repl_skin.pyin your CLI package - Import and use
ReplSkinfor the REPL interface:from cli_anything.<software>.utils.repl_skin import ReplSkin skin = ReplSkin("<software>", version="1.0.0") skin.print_banner() # Branded startup box pt_session = skin.create_prompt_session() # prompt_toolkit with history + styling line = skin.get_input(pt_session, project_name="my_project", modified=True) skin.help(commands_dict) # Formatted help listing skin.success("Saved") # ✓ green message skin.error("Not found") # ✗ red message skin.warning("Unsaved") # ⚠ yellow message skin.info("Processing...") # ● blue message skin.status("Key", "value") # Key-value status line skin.table(headers, rows) # Formatted table skin.progress(3, 10, "...") # Progress bar skin.print_goodbye() # Styled exit message - Make REPL the default behavior: use
invoke_without_command=Trueon the main Click group, and invoke thereplcommand when no subcommand is given:@click.group(invoke_without_command=True) @click.pass_context def cli(ctx, ...): ... if ctx.invoked_subcommand is None: ctx.invoke(repl, project_path=None) - This ensures
cli-anything-<software>with no arguments enters the REPL
- Copy
Phase 4: Test Planning (TEST.md - Part 1)
BEFORE writing any test code, create a TEST.md file in the
agent-harness/cli_anything/<software>/tests/ directory. This file serves as your test plan and
MUST contain:
-
Test Inventory Plan — List planned test files and estimated test counts:
test_core.py: XX unit tests plannedtest_full_e2e.py: XX E2E tests planned
-
Unit Test Plan — For each core module, describe what will be tested:
- Module name (e.g.,
project.py) - Functions to test
- Edge cases to cover (invalid inputs, boundary conditions, error handling)
- Expected test count
- Module name (e.g.,
-
E2E Test Plan — Describe the real-world scenarios to test:
- What workflows will be simulated?
- What real files will be generated/processed?
- What output properties will be verified?
- What format validations will be performed?
-
Realistic Workflow Scenarios — Detail each multi-step workflow:
- Workflow name: Brief title
- Simulates: What real-world task (e.g., "photo editing pipeline", "podcast production", "product render setup")
- Operations chained: Step-by-step operations
- Verified: What output properties will be checked
This planning document ensures comprehensive test coverage before writing code.
Phase 5: Test Implementation
Now write the actual test code based on the TEST.md plan:
-
Unit tests (
test_core.py) — Every core function tested in isolation with synthetic data. No external dependencies. -
E2E tests — intermediate files (
test_full_e2e.py) — Verify the project files your CLI generates are structurally correct (valid XML, correct ZIP structure, etc.) -
E2E tests — true backend (
test_full_e2e.py) — MUST invoke the real software. Create a project, export via the actual software backend, and verify the output:- File exists and size > 0
- Correct format (PDF magic bytes
%PDF-, DOCX/XLSX/PPTX is valid ZIP/OOXML, etc.) - Content verification where possible (CSV contains expected data, etc.)
- Print artifact paths so users can manually inspect:
print(f"\n PDF: {path} ({size:,} bytes)") - No graceful degradation — if the software isn't installed, tests fail, not skip
-
Output verification — Don't trust that export works just because it exits successfully. Verify outputs programmatically:
- Magic bytes / file format validation
- ZIP structure for OOXML formats (DOCX, XLSX, PPTX)
- Pixel-level analysis for video/images (probe frames, compare brightness)
- Audio analysis (RMS levels, spectral comparison)
- Duration/format checks against expected values
-
CLI subprocess tests — Test the installed CLI command as a real user/agent would. The subprocess tests MUST also produce real final output (not just ODF intermediate). Use the
_resolve_clihelper to run the installedcli-anything-<software>command:def _resolve_cli(name): """Resolve installed CLI command; falls back to python -m for dev. Set env CLI_ANYTHING_FORCE_INSTALLED=1 to require the installed command. """ import shutil force = os.environ.get("CLI_ANYTHING_FORCE_INSTALLED", "").strip() == "1" path = shutil.which(name) if path: print(f"[_resolve_cli] Using installed command: {path}") return [path] if force: raise RuntimeError(f"{name} not found in PATH. Install with: pip install -e .") module = name.replace("cli-anything-", "cli_anything.") + "." + name.split("-")[-1] + "_cli" print(f"[_resolve_cli] Falling back to: {sys.executable} -m {module}") return [sys.executable, "-m", module] class TestCLISubprocess: CLI_BASE = _resolve_cli("cli-anything-<software>") def _run(self, args, check=True): return subprocess.run( self.CLI_BASE + args, capture_output=True, text=True, check=check, ) def test_help(self): result = self._run(["--help"]) assert result.returncode == 0 def test_project_new_json(self, tmp_dir): out = os.path.join(tmp_dir, "test.json") result = self._run(["--json", "project", "new", "-o", out]) assert result.returncode == 0 data = json.loads(result.stdout) # ... verify structureKey rules for subprocess tests:
- Always use
_resolve_cli("cli-anything-<software>")— never hardcodesys.executableor module paths directly - Do NOT set
cwd— installed commands must work from any directory - Use
CLI_ANYTHING_FORCE_INSTALLED=1in CI/release testing to ensure the installed command (not a fallback) is being tested - Test
--help,--json, project creation, key commands, and full workflows
- Always use
-
Round-trip test — Create project via CLI, open in GUI, verify correctness
-
Agent test — Have an AI agent complete a real task using only the CLI
Phase 6: Test Documentation (TEST.md - Part 2)
After running all tests successfully, append to the existing TEST.md:
- Test Results — Paste the full
pytest -v --tb=nooutput showing all tests passing with their names and status - Summary Statistics — Total tests, pass rate, execution time
- Coverage Notes — Any gaps or areas not covered by tests
The TEST.md now serves as both the test plan (written before implementation) and the test results documentation (appended after execution), providing a complete record of the testing process.
Critical Lessons Learned
Use the Real Software — Don't Reimplement It
This is the #1 rule. The CLI MUST call the actual software for rendering and export — not reimplement the software's functionality in Python.
The anti-pattern: Building a Pillow-based image compositor to replace GIMP, or generating bpy scripts without ever calling Blender. This produces a toy that can't handle real workloads and diverges from the actual software's behavior.
The correct approach:
-
Use the software's CLI/scripting interface as the backend:
- LibreOffice:
libreoffice --headless --convert-to pdf/docx/xlsx/pptx - Blender:
blender --background --python script.py - GIMP:
gimp -i -b '(script-fu-console-eval ...)' - Inkscape:
inkscape --actions="..." --export-filename=... - Shotcut/Kdenlive:
melt project.mlt -consumer avformat:output.mp4 - Audacity:
soxfor effects processing - OBS:
obs-websocketprotocol
- LibreOffice:
-
The software is a required dependency, not optional. Add it to installation instructions. The CLI is useless without the actual software.
-
Generate valid project/intermediate files (ODF, MLT XML, .blend, SVG, etc.) then hand them to the real software for rendering. Your CLI is a structured command-line interface to the software, not a replacement for it.
Example — LibreOffice CLI export pipeline:
# 1. Build the document as a valid ODF file (our XML builder)
odf_path = write_odf(tmp_path, doc_type, project)
# 2. Convert via the REAL LibreOffice (not a reimplementation)
subprocess.run([
"libreoffice", "--headless",
"--convert-to", "pdf",
"--outdir", output_dir,
odf_path,
])
# Result: a real PDF rendered by LibreOffice's full engine
The Rendering Gap
This is the #2 pitfall. Most GUI apps apply effects at render time via their engine. When you build a CLI that manipulates project files directly, you must also handle rendering — and naive approaches will silently drop effects.
The problem: Your CLI adds filters/effects to the project file format. But when rendering, if you use a simple tool (e.g., ffmpeg concat demuxer), it reads raw media files and ignores all project-level effects. The output looks identical to the input. Users can't tell anything happened.
The solution — a filter translation layer:
- Best case: Use the app's native renderer (
meltfor MLT projects). It reads the project file and applies everything. - Fallback: Build a translation layer that converts project-format effects into
the rendering tool's native syntax (e.g., MLT filters → ffmpeg
-filter_complex). - Last resort: Generate a render script the user can run manually.
Priority order for rendering: native engine → translated filtergraph → script.
Filter Translation Pitfalls
When translating effects between formats (e.g., MLT → ffmpeg), watch for:
- Duplicate filter types: Some tools (ffmpeg) don't allow the same filter twice
in a chain. If your project has both
brightnessandsaturationfilters, and both map to ffmpeg'seq=, you must merge them into a singleeq=brightness=X:saturation=Y. - Ordering constraints: ffmpeg's
concatfilter requires interleaved stream ordering:[v0][a0][v1][a1][v2][a2], NOT grouped[v0][v1][v2][a0][a1][a2]. The error message ("media type mismatch") is cryptic if you don't know this. - Parameter space differences: Effect parameters often use different scales.
MLT brightness
1.15= +15%, but ffmpegeq=brightness=0.06on a -1..1 scale. Document every mapping explicitly. - Unmappable effects: Some effects have no equivalent in the render tool. Handle gracefully (warn, skip) rather than crash.
Timecode Precision
Non-integer frame rates (29.97fps = 30000/1001) cause cumulative rounding errors:
- Use
round(), notint()for float-to-frame conversion.int(9000 * 29.97)truncates and loses frames;round()gets the right answer. - Use integer arithmetic for timecode display. Convert frames → total milliseconds
via
round(frames * fps_den * 1000 / fps_num), then decompose with integer division. Avoid intermediate floats that drift over long durations. - Accept ±1 frame tolerance in roundtrip tests at non-integer FPS. Exact equality is mathematically impossible.
Output Verification Methodology
Never assume an export is correct just because it ran without errors. Verify:
# Video: probe specific frames with ffmpeg
# Frame 0 for fade-in (should be near-black)
# Middle frames for color effects (compare brightness/saturation vs source)
# Last frame for fade-out (should be near-black)
# When comparing pixel values between different resolutions,
# exclude letterboxing/pillarboxing (black padding bars).
# A vertical video in a horizontal frame will have ~40% black pixels.
# Audio: check RMS levels at start/end for fades
# Compare spectral characteristics against source
Testing Strategy
Four test layers with complementary purposes:
- Unit tests (
test_core.py): Synthetic data, no external dependencies. Tests every function in isolation. Fast, deterministic, good for CI. - E2E tests — native (
test_full_e2e.py): Tests the project file generation pipeline (ODF structure, XML content, format validation). Verifies the intermediate files your CLI produces are correct. - E2E tests — true backend (
test_full_e2e.py): Invokes the real software (LibreOffice, Blender, melt, etc.) to produce final output files (PDF, DOCX, rendered images, videos). Verifies the output files:- Exist and have size > 0
- Have correct format (magic bytes, ZIP structure, etc.)
- Contain expected content where verifiable
- Print artifact paths so users can manually inspect results
- CLI subprocess tests (in
test_full_e2e.py): Invokes the installedcli-anything-<software>command viasubprocess.runto run the full workflow end-to-end: create project → add content → export via real software → verify output.
No graceful degradation. The real software MUST be installed. Tests must NOT skip or fake results when the software is missing — the CLI is useless without it. The software is a hard dependency, not optional.
Example — true E2E test for LibreOffice:
class TestWriterToPDF:
def test_rich_writer_to_pdf(self, tmp_dir):
proj = create_document(doc_type="writer", name="Report")
add_heading(proj, text="Quarterly Report", level=1)
add_table(proj, rows=3, cols=3, data=[...])
pdf_path = os.path.join(tmp_dir, "report.pdf")
result = export(proj, pdf_path, preset="pdf", overwrite=True)
# Verify the REAL output file
assert os.path.exists(result["output"])
assert result["file_size"] > 1000 # Not suspiciously small
with open(result["output"], "rb") as f:
assert f.read(5) == b"%PDF-" # Validate format magic bytes
print(f"\n PDF: {result['output']} ({result['file_size']:,} bytes)")
class TestCLISubprocessE2E:
CLI_BASE = _resolve_cli("cli-anything-libreoffice")
def test_full_writer_pdf_workflow(self, tmp_dir):
proj_path = os.path.join(tmp_dir, "test.json")
pdf_path = os.path.join(tmp_dir, "output.pdf")
self._run(["document", "new", "-o", proj_path, "--type", "writer"])
self._run(["--project", proj_path, "writer", "add-heading", "-t", "Title"])
self._run(["--project", proj_path, "export", "render", pdf_path, "-p", "pdf", "--overwrite"])
assert os.path.exists(pdf_path)
with open(pdf_path, "rb") as f:
assert f.read(5) == b"%PDF-"
Run tests in force-installed mode to guarantee the real command is used:
CLI_ANYTHING_FORCE_INSTALLED=1 python3 -m pytest cli_anything/<software>/tests/ -v -s
The -s flag shows the [_resolve_cli] print output confirming which backend
is being used and prints artifact paths for manual inspection.
Real-world workflow test scenarios should include:
- Multi-segment editing (YouTube-style cut/trim)
- Montage assembly (many short clips)
- Picture-in-picture compositing
- Color grading pipelines
- Audio mixing (podcast-style)
- Heavy undo/redo stress testing
- Save/load round-trips of complex projects
- Iterative refinement (add, modify, remove, re-add)
Key Principles
- Use the real software — The CLI MUST invoke the actual application for rendering and export. Generate valid intermediate files (ODF, MLT XML, .blend, SVG), then hand them to the real software. Never reimplement the rendering engine in Python.
- The software is a hard dependency — Not optional, not gracefully degraded. If
LibreOffice isn't installed,
cli-anything-libreofficemust error clearly, not silently produce inferior output with a fallback library. - Manipulate the native format directly — Parse and modify the app's native project files (MLT XML, ODF, SVG, etc.) as the data layer.
- Leverage existing CLI tools — Use
libreoffice --headless,blender --background,melt,ffmpeg,inkscape --actions,soxas subprocesses for rendering. - Verify rendering produces correct output — See "The Rendering Gap" above.
- E2E tests must produce real artifacts — PDF, DOCX, rendered images, videos. Print output paths so users can inspect. Never test only the intermediate format.
- Fail loudly and clearly — Agents need unambiguous error messages to self-correct.
- Be idempotent where possible — Running the same command twice should be safe.
- Provide introspection —
info,list,statuscommands are critical for agents to understand current state before acting. - JSON output mode — Every command should support
--jsonfor machine parsing.
Rules
- The real software MUST be a hard dependency. The CLI must invoke the actual software (LibreOffice, Blender, GIMP, etc.) for rendering and export. Do NOT reimplement rendering in Python. Do NOT gracefully degrade to a fallback library. If the software is not installed, the CLI must error with clear install instructions.
- Every
cli_anything/<software>/directory MUST contain aREADME.mdthat explains how to install the software dependency, install the CLI, run tests, and shows basic usage. - E2E tests MUST invoke the real software and produce real output files (PDF, DOCX, rendered images, videos). Tests must verify output exists, has correct format, and print artifact paths so users can inspect results. Never test only intermediate files.
- Every export/render function MUST be verified with programmatic output analysis before being marked as working. "It ran without errors" is not sufficient.
- Every filter/effect in the registry MUST have a corresponding render mapping or be explicitly documented as "project-only (not rendered)".
- Test suites MUST include real-file E2E tests, not just unit tests with synthetic data. Format assumptions break constantly with real media.
- E2E tests MUST include subprocess tests that invoke the installed
cli-anything-<software>command via_resolve_cli(). Tests must work against the actual installed package, not just source imports. - Every
cli_anything/<software>/tests/directory MUST contain aTEST.mddocumenting what the tests cover, what realistic workflows are tested, and the full test results output. - Every CLI MUST use the unified REPL skin (
repl_skin.py) for the interactive mode. Copycli-anything-plugin/repl_skin.pytoutils/repl_skin.pyand useReplSkinfor the banner, prompt, help, messages, and goodbye. REPL MUST be the default behavior when the CLI is invoked without a subcommand (invoke_without_command=True).
Directory Structure
<software>/
└── agent-harness/
├── <SOFTWARE>.md # Project-specific analysis and SOP
├── setup.py # PyPI package configuration (Phase 7)
├── cli_anything/ # Namespace package (NO __init__.py here)
│ └── <software>/ # Sub-package for this CLI
│ ├── __init__.py
│ ├── __main__.py # python3 -m cli_anything.<software>
│ ├── README.md # HOW TO RUN — required
│ ├── <software>_cli.py # Main CLI entry point (Click + REPL)
│ ├── core/ # Core modules (one per domain)
│ │ ├── __init__.py
│ │ ├── project.py # Project create/open/save/info
│ │ ├── ... # Domain-specific modules
│ │ ├── export.py # Render pipeline + filter translation
│ │ └── session.py # Stateful session, undo/redo
│ ├── utils/ # Shared utilities
│ │ ├── __init__.py
│ │ ├── <software>_backend.py # Backend: invokes the real software
│ │ └── repl_skin.py # Unified REPL skin (copy from plugin)
│ └── tests/ # Test suites
│ ├── TEST.md # Test documentation and results — required
│ ├── test_core.py # Unit tests (synthetic data)
│ └── test_full_e2e.py # E2E tests (real files)
└── examples/ # Example scripts and workflows
Critical: The cli_anything/ directory must NOT contain an __init__.py.
This is what makes it a PEP 420 namespace package — multiple separately-installed
PyPI packages can each contribute a sub-package under cli_anything/ without
conflicting. For example, cli-anything-gimp adds cli_anything/gimp/ and
cli-anything-blender adds cli_anything/blender/, and both coexist in the
same Python environment.
Note: This HARNESS.md is part of the cli-anything-plugin. Individual software directories reference this file — do NOT duplicate it.
Applying This to Other Software
This same SOP applies to any GUI application:
| Software | Backend CLI | Native Format | System Package | How the CLI Uses It |
|---|---|---|---|---|
| LibreOffice | libreoffice --headless |
.odt/.ods/.odp (ODF ZIP) | apt install libreoffice |
Generate ODF → convert to PDF/DOCX/XLSX/PPTX |
| Blender | blender --background --python |
.blend-cli.json | apt install blender |
Generate bpy script → Blender renders to PNG/MP4 |
| GIMP | gimp -i -b '(script-fu ...)' |
.xcf | apt install gimp |
Script-Fu commands → GIMP processes & exports |
| Inkscape | inkscape --actions="..." |
.svg (XML) | apt install inkscape |
Manipulate SVG → Inkscape exports to PNG/PDF |
| Shotcut/Kdenlive | melt or ffmpeg |
.mlt (XML) | apt install melt ffmpeg |
Build MLT XML → melt/ffmpeg renders video |
| Audacity | sox |
.aup3 | apt install sox |
Generate sox commands → sox processes audio |
| OBS Studio | obs-websocket |
scene.json | apt install obs-studio |
WebSocket API → OBS captures/records |
The software is a required dependency, not optional. The CLI generates valid intermediate files (ODF, MLT XML, bpy scripts, SVG) and hands them to the real software for rendering. This is what makes the CLI actually useful — it's a command-line interface TO the software, not a replacement for it.
The pattern is always the same: build the data → call the real software → verify the output.
Phase 7: PyPI Publishing and Installation
After building and testing the CLI, make it installable and discoverable.
All cli-anything CLIs use PEP 420 namespace packages under the shared
cli_anything namespace. This allows multiple CLI packages to be installed
side-by-side in the same Python environment without conflicts.
-
Structure the package as a namespace package:
agent-harness/ ├── setup.py └── cli_anything/ # NO __init__.py here (namespace package) └── <software>/ # e.g., gimp, blender, audacity ├── __init__.py # HAS __init__.py (regular sub-package) ├── <software>_cli.py ├── core/ ├── utils/ └── tests/The key rule:
cli_anything/has no__init__.py. Each sub-package (gimp/,blender/, etc.) does have__init__.py. This is what enables multiple packages to contribute to the same namespace. -
Create setup.py in the
agent-harness/directory:from setuptools import setup, find_namespace_packages setup( name="cli-anything-<software>", version="1.0.0", packages=find_namespace_packages(include=["cli_anything.*"]), install_requires=[ "click>=8.0.0", "prompt-toolkit>=3.0.0", # Add Python library dependencies here ], entry_points={ "console_scripts": [ "cli-anything-<software>=cli_anything.<software>.<software>_cli:main", ], }, python_requires=">=3.10", )Important details:
- Use
find_namespace_packages, NOTfind_packages - Use
include=["cli_anything.*"]to scope discovery - Entry point format:
cli_anything.<software>.<software>_cli:main - The system package (LibreOffice, Blender, etc.) is a hard dependency
that cannot be expressed in
install_requires. Document it in README.md and have the backend module raise a clear error with install instructions:# In utils/<software>_backend.py def find_<software>(): path = shutil.which("<software>") if path: return path raise RuntimeError( "<Software> is not installed. Install it with:\n" " apt install <software> # Debian/Ubuntu\n" " brew install <software> # macOS" )
- Use
-
All imports use the
cli_anything.<software>prefix:from cli_anything.gimp.core.project import create_project from cli_anything.gimp.core.session import Session from cli_anything.blender.core.scene import create_scene -
Test local installation:
cd /root/cli-anything/<software>/agent-harness pip install -e . -
Verify PATH installation:
which cli-anything-<software> cli-anything-<software> --help -
Run tests against the installed command:
cd /root/cli-anything/<software>/agent-harness CLI_ANYTHING_FORCE_INSTALLED=1 python3 -m pytest cli_anything/<software>/tests/ -v -sThe output must show
[_resolve_cli] Using installed command: /path/to/cli-anything-<software>confirming subprocess tests ran against the real installed binary, not a module fallback. -
Verify namespace works across packages (when multiple CLIs installed):
import cli_anything.gimp import cli_anything.blender # Both resolve to their respective source directories
Why namespace packages:
- Multiple CLIs coexist in the same Python environment without conflicts
- Clean, organized imports under a single
cli_anythingnamespace - Each CLI is independently installable/uninstallable via pip
- Agents can discover all installed CLIs via
cli_anything.* - Standard Python packaging — no hacks or workarounds