feat(l4d2-web): emit hostname in spec config with ephemeral fallback

l4d2web/services/l4d2_facade.py

@@ -11,6 +11,7 @@ from l4d2web.models import (
     Overlay,
     OverlayWorkshopItem,
     Server,
+    User,
     WorkshopItem,
 )
 from l4d2web.services import host_commands
@@ -30,6 +31,8 @@ def build_server_spec_payload(
     server: Server,
     blueprint: Blueprint,
     overlay_rows: list[tuple[int, str, bool]],
+    *,
+    resolved_hostname: str = "",
 ) -> dict:
     overlays: list[dict] = []
     for overlay_id, path, expose in overlay_rows:
@@ -45,8 +48,10 @@ def build_server_spec_payload(
         if expose
     ]
     config_lines: list[str] = exec_lines + json.loads(blueprint.config)
-    # rcon_password is appended LAST so neither overlays nor user blueprint
-    # config can override it (Source's cvar semantics are last-wins).
+    if resolved_hostname:
+        config_lines.append(f'hostname "{resolved_hostname}"')
+    # rcon_password is appended LAST so neither overlays, blueprint config,
+    # nor hostname can override it (Source's cvar semantics are last-wins).
     if server.rcon_password:
         config_lines.append(f'rcon_password "{server.rcon_password}"')
     return {
@@ -98,7 +103,17 @@ def initialize_server(server_id: int, on_stdout=None, on_stderr=None, should_can
     # than mount a partial overlay (would silently leave maps missing in-game).
     _check_workshop_overlay_caches(blueprint_id=blueprint.id)
 
-    spec_path = write_temp_spec(build_server_spec_payload(server, blueprint, overlay_rows))
+    # Resolve hostname — explicit override or ephemeral fallback
+    if server.hostname:
+        resolved_hostname = server.hostname
+    else:
+        with session_scope() as db:
+            user = db.get(User, server.user_id)
+            resolved_hostname = f"{user.username} {server.name}"
+
+    spec_path = write_temp_spec(build_server_spec_payload(
+        server, blueprint, overlay_rows, resolved_hostname=resolved_hostname,
+    ))
     try:
         host_commands.run_command(
             ["l4d2ctl", "initialize", server_unit_name(server.id), "-f", str(spec_path)],

l4d2web/tests/test_l4d2_facade.py

@@ -385,3 +385,54 @@ def test_build_server_spec_payload_omits_rcon_password_when_empty() -> None:
         assert not line.startswith("rcon_password ")
 
 
+# ---------------------------------------------------------------------------
+# build_server_spec_payload — hostname injection
+# ---------------------------------------------------------------------------
+
+
+def test_build_server_spec_payload_injects_hostname() -> None:
+    from l4d2web.services.l4d2_facade import build_server_spec_payload
+
+    bp = Blueprint(id=1, user_id=1, name="bp", arguments="[]", config='["sv_consistency 1"]')
+    srv = Server(id=1, user_id=1, blueprint_id=1, name="alpha", port=27015, rcon_password="sekret")
+    spec = build_server_spec_payload(srv, bp, [], resolved_hostname="My Server")
+    cfg = spec["config"]
+    assert 'hostname "My Server"' in cfg
+    assert cfg[-1] == 'rcon_password "sekret"'
+
+
+def test_build_server_spec_payload_omits_hostname_when_empty() -> None:
+    from l4d2web.services.l4d2_facade import build_server_spec_payload
+
+    bp = Blueprint(id=1, user_id=1, name="bp", arguments="[]", config="[]")
+    srv = Server(id=1, user_id=1, blueprint_id=1, name="alpha", port=27015, rcon_password="sekret")
+    spec = build_server_spec_payload(srv, bp, [])
+    for line in spec["config"]:
+        assert not line.startswith("hostname ")
+
+
+def test_initialize_server_resolves_fallback_hostname(
+    monkeypatch: pytest.MonkeyPatch, server_with_blueprint,
+) -> None:
+    """When server.hostname is empty, deploy emits hostname "<username> <server.name>"."""
+    from l4d2web.services.l4d2_facade import initialize_server
+
+    spec_contents: list[str] = []
+
+    def fake_run_command(cmd, **kwargs):
+        nonlocal spec_contents
+        spec_path = cmd[cmd.index("-f") + 1]
+        spec_contents.append(Path(spec_path).read_text())
+        return CommandResult(returncode=0, stdout="", stderr="")
+
+    monkeypatch.setattr("l4d2web.services.host_commands.run_command", fake_run_command)
+
+    server_id, _ = server_with_blueprint
+    initialize_server(server_id)
+
+    assert len(spec_contents) == 1
+    assert "hostname" in spec_contents[0]
+    # The fixture creates user "alice" and server named "alpha"
+    assert '"alice alpha"' in spec_contents[0]
+
+