diff --git a/agent/lsp/servers.py b/agent/lsp/servers.py
index 90eeea708e..954db12ff2 100644
--- a/agent/lsp/servers.py
+++ b/agent/lsp/servers.py
@@ -165,13 +165,7 @@ def _spawn_pyright(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
 
 
 def _pm_store_python() -> Optional[str]:
-    """The pm-provisioned interpreter (facts + store layout), or None.
-
-    Under no-boot-through-venv the running process is the store python and
-    ``VIRTUAL_ENV`` is unset, so the old ambient-env probe had nothing to
-    offer; pm's ``python`` fact names the store entry that owns the
-    runtime. It takes the precedence the ambient ``VIRTUAL_ENV`` probe used
-    to have; project-local candidates follow."""
+    """The PM interpreter used when the analyzed project has no environment."""
     try:
         from pm import paths
         from pm.lock import Facts
@@ -189,14 +183,10 @@ def _pm_store_python() -> Optional[str]:
 
 
 def _detect_python(root: str) -> Optional[str]:
-    # pm's store interpreter resolves to a full exe path (its layout is not
-    # a venv), so it is checked directly rather than through the v/sub probe.
-    pm_python = _pm_store_python()
-    if pm_python:
-        return pm_python
+    # Pyright needs the project's dependencies, not Hermes's runtime packages.
     venvs = [v for v in (os.environ.get("VIRTUAL_ENV"), os.path.join(root, ".venv"), os.path.join(root, "venv")) if v]
     paths = (os.path.join(v, sub) for v in venvs for sub in ("bin/python", "bin/python3", "Scripts/python.exe"))
-    return next((p for p in paths if os.path.exists(p)), None)
+    return next((p for p in paths if os.path.exists(p)), None) or _pm_store_python()
 
 
 _warned_once: set = set()
diff --git a/tests/agent/lsp/test_install_and_lint_fixes.py b/tests/agent/lsp/test_install_and_lint_fixes.py
index 731954f49d..ae8c04d063 100644
--- a/tests/agent/lsp/test_install_and_lint_fixes.py
+++ b/tests/agent/lsp/test_install_and_lint_fixes.py
@@ -81,15 +81,15 @@ def test_install_pip_finds_windows_scripts_launcher(tmp_path, monkeypatch):
 
     from agent.lsp import install as install_mod
 
-    def fake_run(cmd, **kwargs):
+    def fake_pip_install(args, **kwargs):
         scripts_dir = install_mod.hermes_lsp_bin_dir().parent / "python-packages" / "Scripts"
         scripts_dir.mkdir(parents=True, exist_ok=True)
         launcher = scripts_dir / "fake-language-server.exe"
-        launcher.write_text("launcher\n")
+        launcher.write_text("launcher\n", encoding="utf-8")
         launcher.chmod(0o755)
         return MagicMock(returncode=0, stderr="")
 
-    monkeypatch.setattr(install_mod.subprocess, "run", fake_run)
+    monkeypatch.setattr("hermes_cli.tools_config._pip_install", fake_pip_install)
 
     resolved = install_mod._install_pip("fake-lsp", "fake-language-server")
 
diff --git a/tests/agent/lsp/test_python_discovery.py b/tests/agent/lsp/test_python_discovery.py
index ee968e9d15..074f4f7991 100644
--- a/tests/agent/lsp/test_python_discovery.py
+++ b/tests/agent/lsp/test_python_discovery.py
@@ -1,14 +1,8 @@
-"""LSP python discovery must resolve the pm store interpreter, not sniff
-VIRTUAL_ENV.
-
-Under no-boot-through-venv the process is the store python
-(``sys.prefix == sys.base_prefix``) and ``VIRTUAL_ENV`` is unset in bundled
-installs, so the old ambient-env probe silently degraded to project-dir
-probing. pm's ``python`` fact (facts.json + store layout) is the authority.
-"""
+"""Pyright uses the project environment before the Hermes runtime fallback."""
 
 import json
 import os
+import subprocess
 import sys
 from pathlib import Path
 
@@ -81,3 +75,37 @@ def test_missing_store_entry_is_not_an_answer(tmp_path, monkeypatch):
     monkeypatch.setenv("HERMES_RUNTIME_DIR", str(store))
 
     assert _pm_store_python() is None
+
+
+def test_pyright_uses_the_project_interpreter_before_hermes(tmp_path, monkeypatch):
+    from agent.lsp import servers
+
+    project = tmp_path / "project"
+    project.mkdir()
+    monkeypatch.delenv("VIRTUAL_ENV", raising=False)
+    monkeypatch.setattr(servers, "_pm_store_python", lambda: sys.executable)
+    context = servers.ServerContext(
+        workspace_root=str(project), install_strategy="off",
+        binary_overrides={"pyright": [sys.executable]},
+    )
+    server = servers.find_server_for_file(str(project / "app.py"))
+    assert server is not None
+    spec = server.build_spawn(str(project), context)
+    assert spec.initialization_options["python"]["pythonPath"] == sys.executable
+
+    for environment in (project / ".venv", tmp_path / "explicit-environment"):
+        subprocess.run(
+            [sys.executable, "-m", "venv", "--without-pip", str(environment)],
+            check=True, capture_output=True, text=True, timeout=30,
+        )
+        python = environment / ("Scripts/python.exe" if os.name == "nt" else "bin/python")
+        if environment.name == "explicit-environment":
+            monkeypatch.setenv("VIRTUAL_ENV", str(environment))
+        spec = server.build_spawn(str(project), context)
+        selected = spec.initialization_options["python"]["pythonPath"]
+        assert Path(selected) == python
+        child = subprocess.run(
+            [selected, "-I", "-c", "import sys; print(sys.prefix)"],
+            check=True, capture_output=True, text=True, timeout=10,
+        )
+        assert Path(child.stdout.strip()) == environment