Show failed creations in dstack preset

`list_agent_sessions` dropped any session whose status was not `running`,
`interrupted` or `success`, so a creation that failed disappeared from the
listing entirely. `_STATUS_DISPLAY` already had a red `failed` entry that
nothing could reach.

A failure is an outcome worth showing. One session here spent six hours and
seven trials establishing that a constraint was unreachable on the available
hardware, then correctly declined to save a preset. Its trials, learnings and
final report are all on disk, but the only way back to them was to already
know the preset id.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Andrey Cheptsov

src/dstack/_internal/cli/services/presets/session.py

@@ -424,7 +424,7 @@ def list_agent_sessions() -> list[dict[str, Any]]:
         path = session.path
         manifest = session.read_manifest()
         status = manifest.get("status")
-        if status not in ("running", "interrupted", "success"):
+        if status not in ("running", "interrupted", "success", "failed"):
             continue
         if status == "running" and not session_process_alive(manifest):
             status = "interrupted"

src/tests/_internal/cli/services/presets/test_create.py

@@ -833,6 +833,22 @@ def test_load_agent_session_reads_any_status(self, tmp_path, monkeypatch):
         with pytest.raises(CLIError, match="Unknown preset"):
             load_agent_session("nope0000")
 
+    def test_lists_a_failed_session(self, tmp_path, monkeypatch):
+        from dstack._internal.cli.services.presets.session import list_agent_sessions
+
+        # A creation that failed is an outcome worth showing: without this the run
+        # disappears from `dstack preset` and only its id can reach it.
+        self._session(tmp_path, "dead0000", "failed", "[t] boom\n")
+        self._session(tmp_path, "beef0000", "success", "[t] saved preset\n")
+        monkeypatch.setattr(
+            "dstack._internal.cli.services.presets.session.get_presets_dir",
+            lambda: tmp_path,
+        )
+
+        listed = {entry["id"]: entry["status"] for entry in list_agent_sessions()}
+
+        assert listed == {"dead0000": "failed", "beef0000": "success"}
+
     def test_print_session_log_dumps_log_verbatim(self, tmp_path, monkeypatch, capsys):
         session = self._session(
             tmp_path, "abcd0000", "success", "[t] trial 1 done\n[t] saved preset\n"