fix(tui): show scan failure reason

strix/interface/tui/app.py

@@ -36,7 +36,7 @@ from strix.config.models import is_recommended_or_frontier_model
 from strix.core.hooks import BudgetExceededError
 from strix.core.inputs import DEFAULT_MAX_TURNS
 from strix.core.runner import run_strix_scan
-from strix.interface.tui.live_view import TuiLiveView
+from strix.interface.tui.live_view import SCAN_FAILURE_AGENT_ID, TuiLiveView
 from strix.interface.tui.messages import send_user_message_to_agent
 from strix.interface.tui.renderers import render_tool_widget
 from strix.interface.tui.renderers.agent_message_renderer import AgentMessageRenderer
@@ -814,6 +814,7 @@ class StrixTUIApp(App):  # type: ignore[misc]
         self._scan_stop_event = threading.Event()
         self._scan_completed = threading.Event()
         self._scan_error: BaseException | None = None
+        self._scan_error_noted = False
         self._error_noted_agents: set[str] = set()
         self._budget_pause_notified = False
 
@@ -1000,6 +1001,8 @@ class StrixTUIApp(App):  # type: ignore[misc]
         except (ValueError, Exception):
             return
 
+        self._record_scan_error_if_needed()
+
         self._sync_agent_graph()
 
         for agent_id, agent_data in list(self.live_view.agents.items()):
@@ -1017,6 +1020,16 @@ class StrixTUIApp(App):  # type: ignore[misc]
 
         self._update_vulnerabilities_panel()
 
+    def _record_scan_error_if_needed(self) -> None:
+        if self._scan_error is None or self._scan_error_noted:
+            return
+        error_message = str(self._scan_error).strip() or type(self._scan_error).__name__
+        self.live_view.record_scan_error(error_message)
+        self._scan_error_noted = True
+        if not self.selected_agent_id:
+            self.selected_agent_id = SCAN_FAILURE_AGENT_ID
+            self._displayed_events.clear()
+
     def _sync_agent_graph(self) -> None:
         future = self._agent_graph_sync_future
         if future is not None:

strix/interface/tui/live_view.py

@@ -14,6 +14,12 @@ from strix.core.paths import runtime_state_dir
 from strix.interface.tui.history import load_session_history
 
 
+SCAN_FAILURE_AGENT_ID = "scan"
+SCAN_FAILURE_AGENT_NAME = "Scan"
+SCAN_FAILURE_MESSAGE_PREFIX = "Scan failed"
+SCAN_FAILURE_RECOVERY_HINT = "Fix the cause and start a new scan."
+
+
 class TuiLiveView:
     def __init__(self) -> None:
         self.agents: dict[str, dict[str, Any]] = {}
@@ -97,6 +103,23 @@ class TuiLiveView:
             },
         )
 
+    def record_scan_error(self, error: str) -> None:
+        self.upsert_agent(
+            SCAN_FAILURE_AGENT_ID,
+            name=SCAN_FAILURE_AGENT_NAME,
+            status="failed",
+            error_message=error,
+        )
+        self._append_event(
+            SCAN_FAILURE_AGENT_ID,
+            "chat",
+            {
+                "role": "assistant",
+                "content": f"{SCAN_FAILURE_MESSAGE_PREFIX}: {error}\n{SCAN_FAILURE_RECOVERY_HINT}",
+                "metadata": {"source": "scan_error"},
+            },
+        )
+
     def record_user_message(self, agent_id: str, content: str) -> None:
         self._append_event(
             agent_id,

tests/test_tui_scan_failure.py

@@ -0,0 +1,55 @@
+"""Tests for surfacing scan-level failures in the TUI."""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+from typing import TYPE_CHECKING
+
+from strix.interface.tui.app import StrixTUIApp
+
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    import pytest
+
+
+SCAN_FAILURE_TEXT = "model context input is too large"
+
+
+def test_tui_records_scan_failure_once(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.chdir(tmp_path)
+    app = StrixTUIApp(
+        SimpleNamespace(
+            run_name="scan-error-test",
+            targets_info=[],
+            instruction=None,
+            diff_scope={"active": False},
+            scan_mode="deep",
+            non_interactive=False,
+            local_sources=[],
+            scope_mode="auto",
+            diff_base=None,
+            user_explicit_instruction=None,
+        )
+    )
+    app._scan_error = RuntimeError(SCAN_FAILURE_TEXT)
+    app._scan_error_noted = False
+    app.selected_agent_id = None
+    app._displayed_events = []
+
+    app._record_scan_error_if_needed()
+    app._record_scan_error_if_needed()
+
+    scan_agent = app.live_view.agents["scan"]
+    events = app.live_view.events_for_agent("scan")
+
+    assert scan_agent["status"] == "failed"
+    assert scan_agent["error_message"] == SCAN_FAILURE_TEXT
+    assert app.selected_agent_id == "scan"
+    assert len(events) == 1
+    assert "Scan failed" in events[0]["data"]["content"]
+    assert SCAN_FAILURE_TEXT in events[0]["data"]["content"]