fix: Loguru formatting and narrow exception handling

src/copilot_usage/cli.py

@@ -313,12 +313,12 @@ def summary(
     path = path or ctx.obj.get("path")
     try:
         sessions = get_all_sessions(path)
-        render_summary(
-            sessions, since=ensure_aware_opt(since), until=ensure_aware_opt(until)
-        )
-    except Exception as exc:  # noqa: BLE001
-        click.echo(f"Error: {exc}", err=True)
+    except OSError as exc:
+        click.echo(f"Error reading sessions: {exc}", err=True)
         sys.exit(1)
+    render_summary(
+        sessions, since=ensure_aware_opt(since), until=ensure_aware_opt(until)
+    )
 
 
 # ---------------------------------------------------------------------------
@@ -341,45 +341,42 @@ def session(ctx: click.Context, session_id: str, path: Path | None) -> None:
     path = path or ctx.obj.get("path")
     try:
         event_paths = discover_sessions(path)
-        if not event_paths:
-            click.echo("No sessions found.", err=True)
-            sys.exit(1)
-
-        # Fast path: skip directories that clearly cannot match the prefix.
-        # Only apply the pre-filter on UUID-shaped directory names (36 chars
-        # with 4 dashes), where the directory name IS the session ID.
-        # Non-UUID dirs (e.g. test fixtures) always need a full parse.
-        available: list[str] = []
-        for events_path in event_paths:
-            dir_name = events_path.parent.name
-            is_uuid_dir = len(dir_name) == 36 and dir_name.count("-") == 4
-            if (
-                len(session_id) >= 4
-                and is_uuid_dir
-                and not dir_name.startswith(session_id)
-            ):
-                available.append(dir_name[:8])
-                continue
-            events = parse_events(events_path)
-            if not events:
-                continue
-            s = build_session_summary(events, session_dir=events_path.parent)
-            if s.session_id.startswith(session_id):
-                render_session_detail(events, s)
-                return
-            if s.session_id:
-                available.append(s.session_id[:8])
-
-        click.echo(f"Error: no session matching '{session_id}'", err=True)
-        if available:
-            click.echo(f"Available: {', '.join(available)}", err=True)
+    except OSError as exc:
+        click.echo(f"Error reading sessions: {exc}", err=True)
         sys.exit(1)
-    except SystemExit:
-        raise
-    except Exception as exc:  # noqa: BLE001
-        click.echo(f"Error: {exc}", err=True)
+    if not event_paths:
+        click.echo("No sessions found.", err=True)
         sys.exit(1)
 
+    # Fast path: skip directories that clearly cannot match the prefix.
+    # Only apply the pre-filter on UUID-shaped directory names (36 chars
+    # with 4 dashes), where the directory name IS the session ID.
+    # Non-UUID dirs (e.g. test fixtures) always need a full parse.
+    available: list[str] = []
+    for events_path in event_paths:
+        dir_name = events_path.parent.name
+        is_uuid_dir = len(dir_name) == 36 and dir_name.count("-") == 4
+        if len(session_id) >= 4 and is_uuid_dir and not dir_name.startswith(session_id):
+            available.append(dir_name[:8])
+            continue
+        try:
+            events = parse_events(events_path)
+        except OSError:
+            continue
+        if not events:
+            continue
+        s = build_session_summary(events, session_dir=events_path.parent)
+        if s.session_id.startswith(session_id):
+            render_session_detail(events, s)
+            return
+        if s.session_id:
+            available.append(s.session_id[:8])
+
+    click.echo(f"Error: no session matching '{session_id}'", err=True)
+    if available:
+        click.echo(f"Available: {', '.join(available)}", err=True)
+    sys.exit(1)
+
 
 # ---------------------------------------------------------------------------
 # cost
@@ -417,16 +414,16 @@ def cost(
     path = path or ctx.obj.get("path")
     try:
         sessions = get_all_sessions(path)
-
-        render_cost_view(
-            sessions,
-            since=ensure_aware_opt(since),
-            until=ensure_aware_opt(until),
-        )
-    except Exception as exc:  # noqa: BLE001
-        click.echo(f"Error: {exc}", err=True)
+    except OSError as exc:
+        click.echo(f"Error reading sessions: {exc}", err=True)
         sys.exit(1)
 
+    render_cost_view(
+        sessions,
+        since=ensure_aware_opt(since),
+        until=ensure_aware_opt(until),
+    )
+
 
 # ---------------------------------------------------------------------------
 # live
@@ -447,7 +444,7 @@ def live(ctx: click.Context, path: Path | None) -> None:
     path = path or ctx.obj.get("path")
     try:
         sessions = get_all_sessions(path)
-        render_live_sessions(sessions)
-    except Exception as exc:  # noqa: BLE001
-        click.echo(f"Error: {exc}", err=True)
+    except OSError as exc:
+        click.echo(f"Error reading sessions: {exc}", err=True)
         sys.exit(1)
+    render_live_sessions(sessions)

src/copilot_usage/parser.py

@@ -354,8 +354,8 @@ def get_all_sessions(base_path: Path | None = None) -> list[SessionSummary]:
     for events_path in paths:
         try:
             events = parse_events(events_path)
-        except (FileNotFoundError, OSError) as exc:
-            logger.warning("Skipping vanished session %s: %s", events_path, exc)
+        except OSError as exc:
+            logger.warning("Skipping vanished session {}: {}", events_path, exc)
             continue
         if not events:
             continue

tests/copilot_usage/test_cli.py

@@ -268,7 +268,7 @@ def test_summary_invalid_path() -> None:
 
 
 def test_summary_error_handling(tmp_path: Path, monkeypatch: Any) -> None:
-    """Exercise the except-Exception branch (lines 77-79) in summary."""
+    """OSError in get_all_sessions produces a friendly error message."""
 
     def _exploding_sessions(_base: Path | None = None) -> list[object]:
         msg = "disk on fire"
@@ -279,6 +279,7 @@ def _exploding_sessions(_base: Path | None = None) -> list[object]:
     result = runner.invoke(main, ["summary", "--path", str(tmp_path)])
     assert result.exit_code != 0
     assert "disk on fire" in result.output
+    assert "Traceback" not in (result.output or "")
 
 
 def test_session_no_sessions(tmp_path: Path, monkeypatch: Any) -> None:
@@ -319,7 +320,7 @@ def _fake_discover(_base: Path | None = None) -> list[Path]:
 
 
 def test_session_error_handling(tmp_path: Path, monkeypatch: Any) -> None:
-    """Trigger an exception in session detail → friendly error (lines 129-131)."""
+    """PermissionError in discover_sessions produces a friendly error message."""
 
     def _exploding_discover(_base: Path | None = None) -> list[Path]:
         msg = "permission denied"
@@ -387,31 +388,33 @@ def test_cost_zero_multiplier_model(tmp_path: Path) -> None:
 
 
 def test_cost_error_handling(tmp_path: Path, monkeypatch: Any) -> None:
-    """Exercise the except-Exception branch (lines 226-228) in cost."""
+    """OSError in get_all_sessions produces a friendly error message."""
 
     def _exploding_sessions(_base: Path | None = None) -> list[object]:
         msg = "cost explosion"
-        raise RuntimeError(msg)
+        raise OSError(msg)
 
     monkeypatch.setattr("copilot_usage.cli.get_all_sessions", _exploding_sessions)
     runner = CliRunner()
     result = runner.invoke(main, ["cost", "--path", str(tmp_path)])
     assert result.exit_code != 0
     assert "cost explosion" in result.output
+    assert "Traceback" not in (result.output or "")
 
 
 def test_live_error_handling(tmp_path: Path, monkeypatch: Any) -> None:
-    """Exercise the except-Exception branch (lines 248-250) in live."""
+    """OSError in get_all_sessions produces a friendly error message."""
 
     def _exploding_sessions(_base: Path | None = None) -> list[object]:
         msg = "live explosion"
-        raise RuntimeError(msg)
+        raise OSError(msg)
 
     monkeypatch.setattr("copilot_usage.cli.get_all_sessions", _exploding_sessions)
     runner = CliRunner()
     result = runner.invoke(main, ["live", "--path", str(tmp_path)])
     assert result.exit_code != 0
     assert "live explosion" in result.output
+    assert "Traceback" not in (result.output or "")
 
 
 # ---------------------------------------------------------------------------