fix(test): drain HTTP fixture server pipes to fix Windows ReadTimeout

run_example_http_server spawned the fixture worker with stdout/stderr as
PIPEs that were never drained. The server logs a line per RPC; once the
(small) Windows OS pipe buffer fills, the server blocks on write() to
stderr, freezing waitress's single asyncore I/O loop — so every later
request hangs with httpx.ReadTimeout. POSIX hid this behind its 64 KiB
pipe buffers.

Drain both pipes in background threads (stderr buffered so the exit-code
error path still surfaces it). Verified on real Windows (Python 3.14,
vgi-rpc 0.20.0): the resumable-scan file goes from a 63s timeout to 1.5s,
6 passed.

With the root cause fixed, un-skip test_continue_on_fresh_client_skips_rebind
on win32 — its "tracked for investigation" skip was this same bug — and
drop the now-unused sys import.

Also gitignore local scratch artifacts (test.json, client-tests/,
docs/time-travel-init-plan.md).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rustyconover

.gitignore

@@ -42,3 +42,8 @@ test-data/v.parquet
 
 # Cloudflare Worker scaffolding
 cloudflare/vgi-storage/node_modules/
+
+# Local scratch / experiment artifacts (not part of the package)
+/test.json
+/client-tests/
+/docs/time-travel-init-plan.md

tests/_http_fixtures.py

@@ -12,9 +12,11 @@
 import socket
 import subprocess
 import sys
+import threading
 import time
 from collections.abc import Iterator, Sequence
 from contextlib import ExitStack, contextmanager
+from io import StringIO
 
 
 def free_port() -> int:
@@ -56,6 +58,29 @@ def run_example_http_server(
         stderr=subprocess.PIPE,
         text=True,
     )
+
+    # Continuously drain stdout/stderr in background threads. The server logs
+    # one or more lines per RPC; left undrained, a chatty run fills the OS pipe
+    # buffer and the server blocks on write() to stderr — freezing waitress's
+    # single I/O loop so every subsequent request hangs (ReadTimeout). Windows
+    # pipe buffers are small enough to hit this within one test file; POSIX's
+    # 64 KiB buffers usually hide it. Buffer stderr so the exit-code check below
+    # can still surface it.
+    captured_stderr = StringIO()
+
+    def _drain(pipe: object, sink: StringIO | None) -> None:
+        assert pipe is not None
+        for line in pipe:  # type: ignore[attr-defined]
+            if sink is not None:
+                sink.write(line)
+
+    drain_threads = [
+        threading.Thread(target=_drain, args=(proc.stdout, None), daemon=True),
+        threading.Thread(target=_drain, args=(proc.stderr, captured_stderr), daemon=True),
+    ]
+    for t in drain_threads:
+        t.start()
+
     try:
         yield
     finally:
@@ -65,13 +90,14 @@ def run_example_http_server(
         except subprocess.TimeoutExpired:
             proc.kill()
             proc.wait(timeout=5)
+        for t in drain_threads:
+            t.join(timeout=5)
 
         # POSIX terminate() -> SIGTERM (-15); Windows terminate() is
         # TerminateProcess(handle, 1), so a cleanly-stopped worker reports 1.
         ok_codes = (0, 1) if sys.platform == "win32" else (0, -15)
         if proc.returncode not in ok_codes:
-            stderr = proc.stderr.read() if proc.stderr is not None else ""
-            raise RuntimeError(f"example HTTP worker exited with code {proc.returncode}: {stderr}")
+            raise RuntimeError(f"example HTTP worker exited with code {proc.returncode}: {captured_stderr.getvalue()}")
 
 
 def start_http_worker(

tests/conformance/test_resumable_scan.py

@@ -10,7 +10,6 @@
 
 from __future__ import annotations
 
-import sys
 from collections.abc import Iterator
 
 import pyarrow as pa
@@ -103,12 +102,6 @@ def test_resume_on_fresh_client_after_node_hop(http_base_url: str) -> None:
     assert rows == expected  # contiguous, complete, no duplicates
 
 
-@pytest.mark.skipif(
-    sys.platform == "win32",
-    reason="deterministic ReadTimeout on Windows CI after the preceding "
-    "resumable scans — suspected fixture-server worker degradation; "
-    "tracked for investigation (passes on every POSIX platform)",
-)
 def test_continue_on_fresh_client_skips_rebind(http_base_url: str) -> None:
     """``table_scan_continue`` resumes from the token alone — no bind/init round-trip.