diff --git a/decnet/agent/app.py b/decnet/agent/app.py
index fb72390..cc5218c 100644
--- a/decnet/agent/app.py
+++ b/decnet/agent/app.py
@@ -59,7 +59,7 @@ class MutateRequest(BaseModel):
 
 @app.get("/health")
 async def health() -> dict[str, str]:
-    return {"status": "ok"}
+    return {"status": "ok", "marker": "push-test-2"}
 
 
 @app.get("/status")
diff --git a/decnet/env.py b/decnet/env.py
index a016c7a..cb64caa 100644
--- a/decnet/env.py
+++ b/decnet/env.py
@@ -6,9 +6,14 @@ from dotenv import load_dotenv
 # Calculate absolute path to the project root
 _ROOT: Path = Path(__file__).parent.parent.absolute()
 
-# Load .env.local first, then fallback to .env
+# Load .env.local first, then fallback to .env.
+# Also check CWD so deployments that install into site-packages (e.g. the
+# self-updater's release slots) can ship a per-host .env.local at the
+# process's working directory without having to edit site-packages.
 load_dotenv(_ROOT / ".env.local")
 load_dotenv(_ROOT / ".env")
+load_dotenv(Path.cwd() / ".env.local")
+load_dotenv(Path.cwd() / ".env")
 
 
 def _port(name: str, default: int) -> int:
diff --git a/decnet/updater/executor.py b/decnet/updater/executor.py
index 8f1813d..ee4a99e 100644
--- a/decnet/updater/executor.py
+++ b/decnet/updater/executor.py
@@ -111,6 +111,16 @@ def _venv_python(release: pathlib.Path) -> pathlib.Path:
     return release / ".venv" / "bin" / "python"
 
 
+def _shared_venv(install_dir: pathlib.Path) -> pathlib.Path:
+    """The one stable venv that agents/updaters run out of.
+
+    Release slots ship source only. We ``pip install --force-reinstall
+    --no-deps`` into this venv on promotion so shebangs never dangle
+    across a rotation.
+    """
+    return install_dir / "venv"
+
+
 # ------------------------------------------------------------------- public
 
 def read_release(release: pathlib.Path) -> Release:
@@ -167,20 +177,29 @@ def extract_tarball(tarball_bytes: bytes, dest: pathlib.Path) -> None:
 
 # ---------------------------------------------------------------- seams
 
-def _run_pip(release: pathlib.Path) -> subprocess.CompletedProcess:
-    """Create a venv in ``release/.venv`` and pip install -e . into it.
+def _run_pip(
+    release: pathlib.Path,
+    install_dir: Optional[pathlib.Path] = None,
+) -> subprocess.CompletedProcess:
+    """pip install ``release`` into the shared venv at ``install_dir/venv``.
+
+    The shared venv is bootstrapped on first use. ``--force-reinstall
+    --no-deps`` replaces site-packages for the decnet package only; the
+    rest of the env stays cached across updates.
 
     Monkeypatched in tests so the test suite never shells out.
     """
-    venv_dir = release / ".venv"
+    idir = install_dir or release.parent.parent  # releases/<slot> -> install_dir
+    venv_dir = _shared_venv(idir)
     if not venv_dir.exists():
         subprocess.run(  # nosec B603
             [sys.executable, "-m", "venv", str(venv_dir)],
             check=True, capture_output=True, text=True,
         )
-    py = _venv_python(release)
+    py = venv_dir / "bin" / "python"
     return subprocess.run(  # nosec B603
-        [str(py), "-m", "pip", "install", "-e", str(release)],
+        [str(py), "-m", "pip", "install", "--force-reinstall", "--no-deps",
+         str(release)],
         check=False, capture_output=True, text=True,
     )
 
@@ -190,41 +209,97 @@ def _spawn_agent(install_dir: pathlib.Path) -> int:
 
     Returns the new PID. Monkeypatched in tests.
     """
-    py = _venv_python(_current_symlink(install_dir).resolve())
+    decnet_bin = _shared_venv(install_dir) / "bin" / "decnet"
+    log_path = install_dir / "agent.spawn.log"
+    # cwd=install_dir so a persistent ``<install_dir>/.env.local`` gets
+    # picked up by decnet.env (which loads from CWD). The release slot
+    # itself is immutable across updates, so the env file cannot live
+    # inside it.
     proc = subprocess.Popen(  # nosec B603
-        [str(py), "-m", "decnet", "agent", "--daemon"],
+        [str(decnet_bin), "agent", "--daemon"],
         start_new_session=True,
-        stdout=subprocess.DEVNULL,
-        stderr=subprocess.DEVNULL,
+        cwd=str(install_dir),
+        stdout=open(log_path, "ab"),  # noqa: SIM115
+        stderr=subprocess.STDOUT,
     )
     _pid_file(install_dir).write_text(str(proc.pid))
     return proc.pid
 
 
-def _stop_agent(install_dir: pathlib.Path, grace: float = AGENT_RESTART_GRACE_S) -> None:
-    """SIGTERM the PID we spawned; SIGKILL if it doesn't exit in ``grace`` s."""
-    pid_file = _pid_file(install_dir)
-    if not pid_file.is_file():
-        return
-    try:
-        pid = int(pid_file.read_text().strip())
-    except (ValueError, OSError):
-        return
-    try:
-        os.kill(pid, signal.SIGTERM)
-    except ProcessLookupError:
-        return
-    deadline = time.monotonic() + grace
-    while time.monotonic() < deadline:
+def _discover_agent_pids() -> list[int]:
+    """Scan /proc for any running ``decnet agent`` process.
+
+    Used as a fallback when agent.pid is missing (e.g., the agent was started
+    by hand rather than by the updater) so an update still produces a clean
+    restart instead of leaving the old in-memory code serving requests.
+    """
+    pids: list[int] = []
+    self_pid = os.getpid()
+    for entry in pathlib.Path("/proc").iterdir():
+        if not entry.name.isdigit():
+            continue
+        pid = int(entry.name)
+        if pid == self_pid:
+            continue
         try:
-            os.kill(pid, 0)
+            raw = (entry / "cmdline").read_bytes()
+        except (FileNotFoundError, PermissionError, OSError):
+            continue
+        argv = [a for a in raw.split(b"\x00") if a]
+        if len(argv) < 2:
+            continue
+        if not argv[0].endswith(b"python") and b"python" not in pathlib.Path(argv[0].decode(errors="ignore")).name.encode():
+            # Allow direct console-script invocation too: argv[0] ends with /decnet
+            if not argv[0].endswith(b"/decnet"):
+                continue
+        if b"decnet" in b" ".join(argv) and b"agent" in argv:
+            pids.append(pid)
+    return pids
+
+
+def _stop_agent(install_dir: pathlib.Path, grace: float = AGENT_RESTART_GRACE_S) -> None:
+    """SIGTERM the agent and wait for it to exit; SIGKILL after ``grace`` s.
+
+    Prefers the PID recorded in ``agent.pid`` (processes we spawned) but
+    falls back to scanning /proc for any ``decnet agent`` so manually-started
+    agents are also restarted cleanly during an update.
+    """
+    pids: list[int] = []
+    pid_file = _pid_file(install_dir)
+    if pid_file.is_file():
+        try:
+            pids.append(int(pid_file.read_text().strip()))
+        except (ValueError, OSError):
+            pass
+    for pid in _discover_agent_pids():
+        if pid not in pids:
+            pids.append(pid)
+    if not pids:
+        return
+    for pid in pids:
+        try:
+            os.kill(pid, signal.SIGTERM)
         except ProcessLookupError:
-            return
-        time.sleep(0.2)
+            continue
+    deadline = time.monotonic() + grace
+    remaining = list(pids)
+    while remaining and time.monotonic() < deadline:
+        remaining = [p for p in remaining if _pid_alive(p)]
+        if remaining:
+            time.sleep(0.2)
+    for pid in remaining:
+        try:
+            os.kill(pid, signal.SIGKILL)
+        except ProcessLookupError:
+            pass
+
+
+def _pid_alive(pid: int) -> bool:
     try:
-        os.kill(pid, signal.SIGKILL)
+        os.kill(pid, 0)
+        return True
     except ProcessLookupError:
-        pass
+        return False
 
 
 def _probe_agent(
@@ -239,8 +314,10 @@ def _probe_agent(
     ca = agent_dir / "ca.crt"
     if not (worker_key.is_file() and worker_crt.is_file() and ca.is_file()):
         return False, f"no mTLS bundle at {agent_dir}"
-    ctx = ssl.create_default_context(cafile=str(ca))
+    ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
     ctx.load_cert_chain(certfile=str(worker_crt), keyfile=str(worker_key))
+    ctx.load_verify_locations(cafile=str(ca))
+    ctx.verify_mode = ssl.CERT_REQUIRED
     ctx.check_hostname = False
 
     last = ""
@@ -407,7 +484,7 @@ def run_update_self(
     _rotate(updater_install_dir)
     _point_current_at(updater_install_dir, _active_dir(updater_install_dir))
 
-    argv = [str(_venv_python(_active_dir(updater_install_dir))), "-m", "decnet", "updater"] + sys.argv[1:]
+    argv = [str(_shared_venv(updater_install_dir) / "bin" / "decnet"), "updater"] + sys.argv[1:]
     if exec_cb is not None:
         exec_cb(argv)  # tests stub this — we don't actually re-exec
         return {"status": "self_update_queued", "argv": argv}
diff --git a/pyproject.toml b/pyproject.toml
index d781fc8..9618637 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,7 +25,9 @@ dependencies = [
     "scapy>=2.6.1",
     "orjson>=3.10",
     "cryptography>=46.0.7",
-    "python-multipart>=0.0.20"
+    "python-multipart>=0.0.20",
+    "httpx>=0.28.1",
+    "requests>=2.33.1"
 ]
 
 [project.optional-dependencies]
diff --git a/tests/updater/test_updater_executor.py b/tests/updater/test_updater_executor.py
index f01ee4e..7eb350a 100644
--- a/tests/updater/test_updater_executor.py
+++ b/tests/updater/test_updater_executor.py
@@ -293,3 +293,25 @@ def test_update_self_pip_failure_leaves_active_intact(
         ex.run_update_self(tb, sha="U", updater_install_dir=install_dir, exec_cb=lambda a: None)
     assert (install_dir / "releases" / "active" / "marker").read_text() == "old-updater"
     assert not (install_dir / "releases" / "active.new").exists()
+
+
+def test_stop_agent_falls_back_to_proc_scan_when_no_pidfile(
+    monkeypatch: pytest.MonkeyPatch,
+    install_dir: pathlib.Path,
+) -> None:
+    """No agent.pid → _stop_agent still terminates agents found via /proc."""
+    killed: list[tuple[int, int]] = []
+
+    def fake_kill(pid: int, sig: int) -> None:
+        killed.append((pid, sig))
+        raise ProcessLookupError  # pretend it already died after SIGTERM
+
+    monkeypatch.setattr(ex, "_discover_agent_pids", lambda: [4242, 4243])
+    monkeypatch.setattr(ex.os, "kill", fake_kill)
+
+    assert not (install_dir / "agent.pid").exists()
+    ex._stop_agent(install_dir, grace=0.0)
+
+    import signal as _signal
+    assert (4242, _signal.SIGTERM) in killed
+    assert (4243, _signal.SIGTERM) in killed