This commit introduces a complete structural and architectural refactor of

Analysis-Ready Code (ARC). The project is now fully migrated to a modern
src/-based Python package layout, with proper packaging via pyproject.toml,
a clean Nix flake, and improved CLI entry points.

Major changes:

• Add `src/arc/` package with clean module structure:
  - arc/__init__.py now contains the main() dispatcher and clipboard helpers
  - arc/__main__.py provides a proper `python -m arc` entry point
  - arc/cli.py rewritten with full argparse-based interface
  - arc/code_processor.py modernized and relocated
  - arc/directory_handler.py rewritten with output_stream support
  - arc/tee.py added for multi-stream output (stdout + buffer)

• Remove legacy top-level modules:
  - cli.py
  - directory_handler.py
  - main.py

• Introduce fully PEP-517 compliant pyproject.toml with console script:
  - arc = arc.__main__:main

• Add Nix flake (`flake.nix`) providing:
  - buildPythonApplication package `arc`
  - `nix run .#arc` app
  - development shell with Python + xclip

• Add Makefile overhaul:
  - automatic detection of Nix vs Python installation
  - unified install/uninstall targets
  - Nix wrapper installation into ~/.local/bin
  - improved help text and shell safety

• Add GitHub CI pipelines:
  - ci-python.yml for Python builds + Makefile tests + arc --help
  - ci-nix.yml for Nix builds, flake checks, dev-shell tests, and `nix run .#arc`

• Refactor and extend unit tests:
  - test_arc.py updated for src/ imports
  - new tests: test_cli.py, test_main.py, test_tee.py
  - improved CodeProcessor and DirectoryHandler tests

• Add egg-info metadata for local builds

• Add build/lib/ tree for compatibility with setuptools (generated)

Overall, this commit modernizes ARC into a clean, robust, and fully packaged
Python/Nix hybrid tool, enabling reproducible builds, solid CLI behavior,
testable architecture, and CI automation.

https://chatgpt.com/share/693933a0-e280-800f-9cf0-26036d15be04

tests/unit/test_tee.py

@@ -0,0 +1,54 @@
+# tests/unit/test_tee.py
+import io
+import os
+import sys
+import unittest
+
+# Ensure src/ is on sys.path when running via discover
+PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
+SRC_ROOT = os.path.join(PROJECT_ROOT, "src")
+if SRC_ROOT not in sys.path:
+    sys.path.insert(0, SRC_ROOT)
+
+from arc.tee import Tee  # noqa: E402
+
+
+class TestTee(unittest.TestCase):
+    def test_write_writes_to_all_streams(self):
+        buf1 = io.StringIO()
+        buf2 = io.StringIO()
+
+        tee = Tee(buf1, buf2)
+        tee.write("hello")
+        tee.write(" world")
+
+        self.assertEqual(buf1.getvalue(), "hello world")
+        self.assertEqual(buf2.getvalue(), "hello world")
+
+    def test_flush_flushes_all_streams(self):
+        class DummyStream:
+            def __init__(self):
+                self.flushed = False
+                self.data = ""
+
+            def write(self, s):
+                self.data += s
+
+            def flush(self):
+                self.flushed = True
+
+        s1 = DummyStream()
+        s2 = DummyStream()
+
+        tee = Tee(s1, s2)
+        tee.write("x")
+        tee.flush()
+
+        self.assertTrue(s1.flushed)
+        self.assertTrue(s2.flushed)
+        self.assertEqual(s1.data, "x")
+        self.assertEqual(s2.data, "x")
+
+
+if __name__ == "__main__":
+    unittest.main()