Fix the Windows and free-threaded CI lanes

Five environment-specific failures, none of them in the computation:

- The precision lint read pyphi sources without an encoding, so Windows
  decoded them as cp1252 and failed on the first non-ASCII byte.
- The import-writes-no-log test built a minimal subprocess environment;
  without SystemRoot, Windows cannot initialize sockets and `import
  asyncio` raises WinError 10106. Inherit the environment instead.
- The campaign tests asserted an executable bit and ran run_task.sh
  through bash, neither of which exists on Windows.
- Escalating every warning to an error turns a dependency's stale escape
  sequence into a SyntaxError the first time its source is compiled,
  which aborts conftest under Python 3.14 (POT). Keep SyntaxWarning
  visible but non-fatal; ruff's W605 covers pyphi's own sources.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019TyrR7G1d7xR6ZK9i92MtF

Author: wmayner

pyproject.toml

@@ -280,6 +280,11 @@ filterwarnings = [
     # reused as a zombie and the next parallel test deadlocks in
     # `future.result()`. Keep it a visible warning, never an error.
     "default:A worker stopped while some jobs were given to the executor:UserWarning",
+    # Emitted by the compiler, so escalating it turns any dependency's stale
+    # escape sequence into a SyntaxError the first time its source is compiled
+    # (POT 0.9.6 under Python 3.14 aborts conftest this way). PyPhi's own
+    # sources are covered by ruff's W605.
+    "default::SyntaxWarning",
 ]
 
 [tool.coverage.run]

test/campaign/test_prepare.py

@@ -1,4 +1,5 @@
 import json
+import os
 
 import pytest
 
@@ -25,7 +26,8 @@ def test_prepare_writes_campaign_directory(tmp_path):
     assert task.kind == "sweep_cells"
     assert task.skip_uncomputable is True
     assert (directory / "outputs").is_dir()
-    assert (directory / "run_task.sh").stat().st_mode & 0o111
+    if os.name == "posix":  # Windows has no executable bit to set
+        assert (directory / "run_task.sh").stat().st_mode & 0o111
     submit = (directory / "pyphi.sub").read_text()
     assert "queue task_id, memory from remaining.txt" in submit
     assert "container_image" in submit

test/campaign/test_prepare_ces.py

@@ -1,4 +1,5 @@
 import json
+import os
 
 import pytest
 
@@ -442,6 +443,9 @@ def _emulate_condor_transfer(campaign_dir, scratch, inputs, preserve: bool):
             shutil.copy2(src, dest)
 
 
+@pytest.mark.skipif(
+    os.name != "posix", reason="run_task.sh needs a POSIX shell and HTCondor is Linux"
+)
 def test_condor_transfer_sandbox_end_to_end(tmp_path):
     """Run every job of a prepared campaign inside a sandbox that emulates
     HTCondor's file transfer for the generated submit file — transfer the

test/test_logging.py

@@ -77,7 +77,9 @@ def test_import_writes_no_log_file(tmp_path):
     import subprocess
     import sys
 
-    env = {"PYPHI_WELCOME_OFF": "1", "PATH": os.environ["PATH"]}
+    # Inherit the environment: a hand-built one drops the variables Windows
+    # needs to initialize sockets, and `import asyncio` then fails.
+    env = os.environ | {"PYPHI_WELCOME_OFF": "1"}
     subprocess.run(
         [sys.executable, "-c", "import pyphi"],
         cwd=tmp_path,

test/test_precision_lint.py

@@ -45,7 +45,7 @@ def _waived(lines: list[str], lineno: int) -> bool:
 
 
 def _violations(path: Path) -> list[str]:
-    source = path.read_text()
+    source = path.read_text(encoding="utf-8")
     lines = source.splitlines()
     tree = ast.parse(source)
     found = []