diff --git a/pyproject.toml b/pyproject.toml
index 6f14751a..100686a3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -93,7 +93,7 @@ testing = [
 repl = [
   "pyperclip>=1.9.0",
   "prompt-toolkit>=3.0.50",
-  "xonsh>=0.22.8",
+  "xonsh>=0.23.0",
   "psutil>=7.0.0",
 ]
 lint = [
@@ -134,7 +134,7 @@ sync_pause = {requires-python = ">=3.13, <3.14"}
 # xonsh = { git = 'https://github.com/anki-code/xonsh.git', branch = 'prompt_next_suggestion' }
 # ^ https://github.com/xonsh/xonsh/pull/6048
 # xonsh = { git = 'https://github.com/xonsh/xonsh.git', branch = 'main' }
-xonsh = { path = "../xonsh", editable = true }
+# xonsh = { path = "../xonsh", editable = true }
 
 # [tool.uv.sources.pdbp]
 # XXX, in case we need to tmp patch again.
@@ -203,7 +203,35 @@ all_bullets = true
 
 [tool.pytest.ini_options]
 minversion = '6.0'
-timeout = 200  # per-test hard limit
+# NOTE: `pytest-timeout`'s global per-test cap is intentionally
+# NOT set — both of its enforcement methods break trio's
+# runtime under our fork-based spawn backends:
+#
+# - `method='signal'` (the default; SIGALRM) raises `Failed`
+#   synchronously from the signal handler in trio's main
+#   thread, which leaves `GLOBAL_RUN_CONTEXT` half-installed
+#   ("Trio guest run got abandoned"). EVERY subsequent
+#   `trio.run()` in the same pytest session then bails with
+#   `RuntimeError: Attempted to call run() from inside a
+#   run()` — full-session poison: a single 200s hang
+#   cascades into 30+ false-positive failures across
+#   downstream test files.
+#
+# - `method='thread'` calls `_thread.interrupt_main()` which
+#   can let the resulting `KeyboardInterrupt` escape trio's
+#   `KIManager` under fork-cascade teardown races, killing
+#   the whole pytest session.
+#
+# For tests that legitimately need a wall-clock cap, use
+# `with trio.fail_after(N):` INSIDE the test — trio's own
+# Cancelled machinery handles the timeout cleanly through
+# the actor nursery without disturbing global state. See
+# `tests/test_advanced_streaming.py::test_dynamic_pub_sub`'s
+# module-level NOTE for the canonical pattern.
+#
+# CI environments should rely on job-level wall-clock
+# timeouts (e.g. GitHub Actions `timeout-minutes`) for an
+# escape hatch on genuinely-stuck suites.
 # https://docs.pytest.org/en/stable/reference/reference.html#configuration-options
 testpaths = [
   'tests'