diff --git a/pm/environment.py b/pm/environment.py
index e48a533623..80877a6421 100644
--- a/pm/environment.py
+++ b/pm/environment.py
@@ -19,6 +19,33 @@ from typing import TextIO
 from pm.package import InstallError
 
 
+def prune_site_pth(venv_dir: Path) -> None:
+    """Drop .pth files that must never execute inside a shipped payload.
+
+    ``uv sync`` leaves two behind: ``_virtualenv.pth`` (repoints
+    ``sys.prefix`` at the venv) and the project's ``__editable__`` pointer
+    (names the BUILD machine — the payload wires the repo snapshot itself,
+    see scripts/build/launcher_wrapper.py). Bundled launchers process every
+    other .pth with ``site.addsitedir()``; pywin32.pth is load-bearing on
+    Windows (win32\\lib on sys.path is what makes ``import pywintypes``
+    resolve, which portalocker/concurrent-log-handler need to write logs).
+    """
+    if (venv_dir / "Scripts").is_dir():
+        sites = [venv_dir / "Lib" / "site-packages"]
+    else:
+        lib = venv_dir / "lib"
+        sites = sorted(lib.glob("python*/site-packages")) if lib.is_dir() else []
+    for site_dir in sites:
+        if not site_dir.is_dir():
+            continue
+        for pth in site_dir.glob("*.pth"):
+            if pth.name == "_virtualenv.pth" or pth.name.startswith("__editable__"):
+                try:
+                    pth.unlink()
+                except OSError:
+                    pass
+
+
 def _run_streaming(command: list[str], *, cwd: Path, env: dict[str, str],
                    timeout: int, output: TextIO) -> subprocess.CompletedProcess:
     """Keep CI progress live, a bounded diagnostic tail, and a wall-clock timeout."""
diff --git a/scripts/build/launcher_wrapper.py b/scripts/build/launcher_wrapper.py
index 9b5c3399bf..d7197d3e2e 100644
--- a/scripts/build/launcher_wrapper.py
+++ b/scripts/build/launcher_wrapper.py
@@ -17,7 +17,11 @@ The wrapper replaces everything the old rust shim + its sidecar did
     on sys.path (same order, same reason as the old shim: the repo's
     hermes_cli wins over anything stale in site-packages — the sealed
     payload's venv has no working editable install, its pointer names the
-    BUILD machine),
+    BUILD machine). The site entry goes through ``site.addsitedir()`` —
+    the only mechanism that runs ``.pth`` files — because pywin32.pth is
+    what puts win32\\lib on sys.path and therefore what makes
+    ``import pywintypes`` resolve on Windows bundles (portalocker's
+    Win32Locker → concurrent-log-handler → hermes_logging.py's files),
   * drop inherited PYTHONPATH / PYTHONHOME so foreign installs can never
     shadow the bundle,
   * default sys.pycache_prefix to the user-level cache (%LOCALAPPDATA%
@@ -31,6 +35,7 @@ directly (tests/scripts/test_desktop_cli_wrapper.py).
 
 import importlib
 import os
+import site
 import sys
 
 HERMES_ENTRY_MODULE = "__HERMES_ENTRY_MODULE__"
@@ -78,8 +83,21 @@ def configure(here, environ=None):
     # the stdlib entirely.
     environ.pop("PYTHONPATH", None)
     environ.pop("PYTHONHOME", None)
-    entries = payload_sys_paths(here)
-    sys.path[0:0] = entries
+    repo_entry, site_entry = payload_sys_paths(here)
+    # Repo snapshot first — its hermes_cli wins over anything stale in
+    # site-packages (the sealed payload has no working editable install).
+    sys.path.insert(0, repo_entry)
+    # addsitedir(), not a raw append: only it processes the venv's .pth
+    # files. pywin32.pth is load-bearing on Windows — it puts win32\lib
+    # on sys.path, which is what makes `import pywintypes` resolve, and
+    # without that portalocker's Win32Locker dies and
+    # concurrent-log-handler silently drops every file-log record (the
+    # same trap gateway/run.py's MCP venv bootstrap works around). Keep
+    # site-packages directly after the repo, ahead of .pth-added dirs.
+    site.addsitedir(site_entry)
+    if site_entry in sys.path:
+        sys.path.remove(site_entry)
+    sys.path.insert(1 if sys.path and sys.path[0] == repo_entry else 0, site_entry)
     if not environ.get("PYTHONPYCACHEPREFIX"):
         default = default_pycache_dir(environ)
         if default:
@@ -88,7 +106,7 @@ def configure(here, environ=None):
             # startup, but setting it in os.environ cannot retro-activate
             # it — sys.pycache_prefix is the live switch.
             sys.pycache_prefix = default
-    return entries
+    return [repo_entry, site_entry]
 
 
 def main(argv=None):
diff --git a/scripts/build/launchers.py b/scripts/build/launchers.py
index 99135bc85c..c7afcfc34d 100644
--- a/scripts/build/launchers.py
+++ b/scripts/build/launchers.py
@@ -42,7 +42,11 @@ export HERMES_NODE="$root/tools/node/data/data/com.termux/files/usr/bin/node"
 export HERMES_RUNTIME_DIR="$root/tools"
 export PATH="$root/tools/npm/bin:$root/tools/node/data/data/com.termux/files/usr/bin:$root/tools/ffmpeg/data/data/com.termux/files/usr/bin:$root/tools/ripgrep:$PATH"
 '''
-    code = f"import sys; sys.argv[0]={name!r}; from {module} import {func}; sys.exit({func}())"
+    code = (
+        f"import os, site, sys; sys.argv[0]={name!r}; "
+        "site.addsitedir(os.environ['HERMES_SITE']); "
+        f"from {module} import {func}; sys.exit({func}())"
+    )
     return f'''{header}
 set -eu
 self="$0"
@@ -60,6 +64,11 @@ SITE={shell_path(site)}
 [ -x "$PYTHON" ] || {{ printf '%s\\n' 'Bundled interpreter missing; reinstall Hermes.' >&2; exit 2; }}
 unset PYTHONPATH PYTHONHOME
 export PYTHONPATH="$REPO:$SITE"
+# PYTHONPATH cannot process .pth files (only site.addsitedir() can), and
+# the venv's .pth files are load-bearing (pywin32.pth -> win32\\lib ->
+# `import pywintypes` on Windows bundles; the win32 wrapper mirrors this
+# in launcher_wrapper.py). The -c bootstrap below runs addsitedir() on it.
+export HERMES_SITE="$SITE"
 export PYTHONPYCACHEPREFIX="${{PYTHONPYCACHEPREFIX:-${{XDG_CACHE_HOME:-$HOME/.cache}}/hermes-pycache}}"
 {extra}exec "$PYTHON" -P -c {shlex.quote(code)} "$@"
 '''
diff --git a/scripts/build/python_env.py b/scripts/build/python_env.py
index b45cdb8972..5a13d87843 100644
--- a/scripts/build/python_env.py
+++ b/scripts/build/python_env.py
@@ -14,7 +14,7 @@ import shutil
 import subprocess
 import sys
 
-from pm.environment import PythonEnvironment
+from pm.environment import PythonEnvironment, prune_site_pth
 from pm.package import InstallError
 
 
@@ -44,6 +44,11 @@ def build_python_environment(
         environment.sync(source, extras=extras, all_extras=all_extras,
                          no_install_project=no_install_project)
         environment.check()
+        # The sealed payload must never process uv's venv-marker or
+        # editable-install .pth files (see pm.environment.prune_site_pth):
+        # the launcher addsitedirs the venv, and those two would repoint
+        # sys.prefix / shadow the repo snapshot with build-machine paths.
+        prune_site_pth(out)
     except BaseException:
         shutil.rmtree(out, ignore_errors=True)
         raise
diff --git a/tests/pm/test_environment_build.py b/tests/pm/test_environment_build.py
index 809aecdf4d..a65640394a 100644
--- a/tests/pm/test_environment_build.py
+++ b/tests/pm/test_environment_build.py
@@ -34,6 +34,39 @@ def _run(command, *, cwd: Path, env: dict) -> str:
     return result.stdout.strip()
 
 
+def test_prune_site_pth_keeps_only_load_bearing_pth(tmp_path):
+    """The payload venv must not carry uv's venv-marker or editable-install
+    .pth files: the launcher addsitedirs the venv, and those two would repoint
+    sys.prefix / shadow the repo snapshot with build-machine paths. Everything
+    else (pywin32.pth!) must survive — it is what makes `import pywintypes`
+    resolve on Windows bundles."""
+    from pm.environment import prune_site_pth
+
+    # Windows layout (Scripts/ present).
+    win_venv = tmp_path / "win-venv"
+    (win_venv / "Scripts").mkdir(parents=True)
+    win_site = win_venv / "Lib" / "site-packages"
+    win_site.mkdir(parents=True)
+    # POSIX layout (bin/ present, versioned site-packages).
+    posix_venv = tmp_path / "posix-venv"
+    (posix_venv / "bin").mkdir(parents=True)
+    posix_site = posix_venv / "lib" / "python3.14" / "site-packages"
+    posix_site.mkdir(parents=True)
+
+    for site in (win_site, posix_site):
+        (site / "pywin32.pth").write_text("win32\nwin32\\lib\nimport pywin32_bootstrap\n", encoding="utf-8")
+        (site / "_virtualenv.pth").write_text("import _virtualenv\n", encoding="utf-8")
+        (site / "__editable__.hermes_agent-0.21.1.pth").write_text(
+            "import __editable___hermes_agent_0_21_1_finder\n", encoding="utf-8"
+        )
+
+    prune_site_pth(win_venv)
+    prune_site_pth(posix_venv)
+
+    assert sorted(p.name for p in win_site.glob("*.pth")) == ["pywin32.pth"]
+    assert sorted(p.name for p in posix_site.glob("*.pth")) == ["pywin32.pth"]
+
+
 @pytest.fixture
 def locked_project(tmp_path):
     uv = shutil.which("uv")
diff --git a/tests/scripts/test_desktop_cli_wrapper.py b/tests/scripts/test_desktop_cli_wrapper.py
index aa60bc693f..88c8ee7c49 100644
--- a/tests/scripts/test_desktop_cli_wrapper.py
+++ b/tests/scripts/test_desktop_cli_wrapper.py
@@ -91,6 +91,36 @@ def test_configure_prepends_repo_then_site_packages(tmp_path):
         sys.path[:] = original
 
 
+def test_configure_processes_site_pth_files(tmp_path):
+    """site-packages goes through site.addsitedir(), not a raw append.
+
+    Only addsitedir() runs .pth files, and pywin32.pth is load-bearing on
+    Windows bundles: it puts win32\\lib on sys.path, which is what makes
+    `import pywintypes` resolve (portalocker's Win32Locker →
+    concurrent-log-handler → hermes_logging.py's file handlers). The old
+    raw sys.path[0:0] = entries skipped .pth processing entirely, silently
+    killing file logging on Windows bundles (and any future .pth-based
+    dependency on every platform).
+    """
+    ns = _load()
+    here = str(tmp_path / "bin")
+    site = os.path.join(here, "..", "venv", "Lib", "site-packages")
+    os.makedirs(site)
+    added = tmp_path / "pth-added"
+    added.mkdir()
+    with open(os.path.join(site, "load-bearing.pth"), "w", encoding="utf-8") as f:
+        f.write(f"{added}\n")
+    original = list(sys.path)
+    try:
+        ns["configure"](here, environ={})
+        repo = os.path.join(here, "..", "repo")
+        # Repo first, site second, .pth-added dirs after both.
+        assert sys.path[:2] == [repo, site]
+        assert sys.path.index(str(added)) > 1
+    finally:
+        sys.path[:] = original
+
+
 def test_configure_drops_inherited_pythonpath_and_pythonhome(tmp_path):
     ns = _load()
     original = list(sys.path)