diff --git a/decnet/engine/deployer.py b/decnet/engine/deployer.py
index fe60a6fb..884c18ca 100644
--- a/decnet/engine/deployer.py
+++ b/decnet/engine/deployer.py
@@ -5,8 +5,10 @@ Deploy, teardown, and status via Docker SDK + subprocess docker compose.
 
 import asyncio
 import json
+import os
 import shutil
 import subprocess  # nosec B404
+import tempfile
 import time
 from pathlib import Path
 from typing import cast
@@ -833,7 +835,16 @@ def _teardown_order(lans: list[dict]) -> list[str]:
 
 
 def _topology_compose_path(topology_id: str) -> Path:
-    return Path(f"decnet-topology-{topology_id[:8]}-compose.yml")
+    # Anchor to a stable absolute dir so write and teardown agree
+    # regardless of process CWD — a CWD-relative path littered the
+    # install tree and let teardown's unlink() miss orphaned files.
+    base = Path(os.environ.get("DECNET_RUN_DIR", "/var/lib/decnet/topologies"))
+    try:
+        base.mkdir(parents=True, exist_ok=True)
+    except OSError:
+        base = Path(tempfile.gettempdir()) / "decnet-topologies"
+        base.mkdir(parents=True, exist_ok=True)
+    return base / f"decnet-topology-{topology_id[:8]}-compose.yml"
 
 
 def _topology_compose_project(topology_id: str) -> str:
diff --git a/tests/topology/test_deploy.py b/tests/topology/test_deploy.py
index 44cb2272..c95e171d 100644
--- a/tests/topology/test_deploy.py
+++ b/tests/topology/test_deploy.py
@@ -51,7 +51,7 @@ async def repo(tmp_path):
 
 @pytest.mark.anyio
 async def test_dry_run_writes_compose_and_preserves_pending(repo, tmp_path, monkeypatch):
-    monkeypatch.chdir(tmp_path)
+    monkeypatch.setenv("DECNET_RUN_DIR", str(tmp_path))
     plan = generate(_cfg())
     tid = await persist(repo, plan)
 
@@ -235,3 +235,22 @@ async def test_deploy_and_teardown_against_real_docker(repo, tmp_path, monkeypat
         p.unlink()
     # Sanity: Path roundtrip still resolvable
     assert isinstance(Path(str(p)), Path)
+
+
+def test_compose_path_is_absolute_and_cwd_independent(tmp_path, monkeypatch):
+    """Regression: a CWD-relative compose path littered the install dir and
+    let teardown's unlink() miss orphans. Path must be absolute and stable
+    across CWD changes so write and teardown always agree."""
+    monkeypatch.setenv("DECNET_RUN_DIR", str(tmp_path))
+    tid = "abcdef1234567890"
+
+    monkeypatch.chdir(tmp_path)
+    p1 = _topology_compose_path(tid)
+    sub = tmp_path / "elsewhere"
+    sub.mkdir()
+    monkeypatch.chdir(sub)
+    p2 = _topology_compose_path(tid)
+
+    assert p1.is_absolute()
+    assert p1 == p2, "compose path must not depend on process CWD"
+    assert p1.parent == tmp_path