Fix index console output and completion UX

USER_GUIDE.md

@@ -633,6 +633,7 @@ cdidx ./myproject
 cdidx ./myproject --rebuild     # full rebuild from scratch
 cdidx ./myproject --verbose     # show per-file details
 cdidx ./myproject --duration-format seconds  # show elapsed time as seconds
+cdidx ./myproject --notify=osc9 # terminal notification after long runs
 cdidx ./myproject --watch       # stay running and reindex on file changes
 cdidx ./myproject --watch --debounce 200   # coalesce bursts within a 200 ms window
 ```
@@ -678,7 +679,9 @@ Done.
 
 During long-running indexing on an interactive terminal, `Indexing...` stays live as a spinner instead of dropping to a fixed line until the next 50-file progress update. Warnings still print immediately, but the spinner resumes right after each warning so the run does not look frozen. When stdout is redirected (for example `cdidx . > out.txt`), cdidx prints a single `Indexing...` line to stdout, keeps warnings on stderr, and emits only line-based progress updates to stdout.
 
-Human output formats elapsed index time with unit labels by default: milliseconds under 1 second, seconds under 1 minute, minutes/seconds under 1 hour, and hours/minutes/seconds after that. Use `--duration-format seconds` for decimal seconds or `--duration-format hms` for the legacy `HH:MM:SS` display. JSON output continues to expose raw `elapsed_ms` for machine consumers.
+Human output uses invariant numeric formatting (`.` decimal separator and `,` thousands separators) regardless of the process locale, matching JSON's culture-independent contract. Elapsed index time uses unit labels by default: milliseconds under 1 second, seconds under 1 minute, minutes/seconds under 1 hour, and hours/minutes/seconds after that. Use `--duration-format seconds` for decimal seconds or `--duration-format hms` for the legacy `HH:MM:SS` display. JSON output continues to expose raw `elapsed_ms` for machine consumers.
+
+For index runs that take at least five seconds, `--notify=<auto|bell|osc9|desktop|none>` controls a completion signal on stderr. `auto` rings the terminal bell only for interactive terminals and stays silent for redirected output; `desktop` currently maps to OSC 9 terminal notification text for terminals that support it. `CDIDX_NOTIFY` sets the same default, and `--quiet` suppresses completion notifications.
 
 Machine-readable output also reports the post-run readiness bits directly:
 
@@ -2323,6 +2326,7 @@ name-based tools では `exactName` を使い、`exact` は後方互換 client 
 | Search snippet lines | `8`（`--snippet-lines`、最大 `20`） | CLI help と search runner |
 | Max line width | `512`（`--max-line-width`、`0` で無効） | `LineWidthFormatter.DefaultMaxLineWidth` |
 | Index max file size | `CDIDX_MAX_FILE_BYTES` 未設定時は `4MiB` | index runner help |
+| Index completion notification | `auto`（interactive terminal は bell、redirected output は none）。`--notify` / `CDIDX_NOTIFY` で上書き | index runner help |
 | Watch debounce | `500` ms（`--debounce`） | index watch runner |
 | Status stale-after hint | `24h`。`--stale-after` / `CDIDX_STALE_AFTER` / `.cdidxrc.json` で上書き | status runner |
 | Color mode | `auto`。`--color` / `CLICOLOR_FORCE` / `NO_COLOR` / `CLICOLOR=0` で上書き | `ConsoleUi` |

changelog.d/unreleased/1629.fixed.md

@@ -0,0 +1,15 @@
+---
+category: fixed
+issues:
+  - 1629
+affected:
+  - src/CodeIndex/Cli/ConsoleUi.cs
+---
+
+## English
+
+- **Console width detection no longer hides unexpected failures (#1629)** — width probing now catches only documented console exceptions, records fallback use, honors `COLUMNS` after failed probing, and emits a one-time verbose trace.
+
+## 日本語
+
+- **console width 検出が想定外の失敗を隠さないようになりました (#1629)** — 幅取得は既知の console 例外だけを捕捉し、fallback 使用を記録し、失敗時に `COLUMNS` を優先し、verbose で一度だけ trace を出します。

changelog.d/unreleased/1662.fixed.md

@@ -0,0 +1,18 @@
+---
+category: fixed
+issues:
+  - 1662
+affected:
+  - src/CodeIndex/Cli/ConsoleUi.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.FullScan.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.Update.cs
+  - USER_GUIDE.md
+---
+
+## English
+
+- **Human CLI index output now uses invariant numeric formatting (#1662)** — progress and index summaries consistently use culture-independent decimal and thousands separators to match JSON-facing expectations.
+
+## 日本語
+
+- **人間向け CLI index 出力が invariant な数値形式を使うようになりました (#1662)** — progress と index summary は JSON の期待と揃うよう、culture に依存しない小数点と桁区切りを一貫して使います。

changelog.d/unreleased/1835.added.md

@@ -0,0 +1,20 @@
+---
+category: added
+issues:
+  - 1835
+affected:
+  - src/CodeIndex/Cli/ConsoleUi.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.Parse.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.FullScan.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.Update.cs
+  - src/CodeIndex/Cli/CliFlagSchema.cs
+  - USER_GUIDE.md
+---
+
+## English
+
+- **Added long index completion notifications (#1835)** — `cdidx index` now supports `--notify=<auto|bell|osc9|desktop|none>` plus `CDIDX_NOTIFY`, with quiet/json-safe suppression and a five-second threshold for human runs.
+
+## 日本語
+
+- **長い index 完了通知を追加しました (#1835)** — `cdidx index` は `--notify=<auto|bell|osc9|desktop|none>` と `CDIDX_NOTIFY` に対応し、人間向け実行では5秒以上の run だけ通知し、quiet/json では抑制します。

changelog.d/unreleased/1963.added.md

@@ -0,0 +1,17 @@
+---
+category: added
+issues:
+  - 1963
+affected:
+  - src/CodeIndex/Cli/ConsoleUi.cs
+  - src/CodeIndex/Cli/IndexCommandRunner.FullScan.cs
+  - USER_GUIDE.md
+---
+
+## English
+
+- **Added post-index next-step guidance (#1963)** — successful human full-scan output now prints concise search, definition, MCP, database, exclusion, and language-summary next steps while preserving JSON and quiet output.
+
+## 日本語
+
+- **index 後の next-step guidance を追加しました (#1963)** — 成功した人間向け full-scan 出力に、search / definition / MCP / database / 除外設定 / language summary の簡潔な案内を出し、JSON と quiet 出力は維持します。

src/CodeIndex/Cli/CliFlagSchema.cs

@@ -210,6 +210,7 @@ private static IReadOnlyList<CliFlag> BuildAll()
             new() { Name = "--silent", Description = "Alias for --quiet", Commands = Set(AllCommands.ToArray()) },
             new() { Name = "--profile", Description = "Emit SQL timing and EXPLAIN QUERY PLAN profile JSON after the normal result", Commands = Set(ProfileCommands) },
             new() { Name = "--verbose", Description = "Emit query debug diagnostics to stderr, or _debug JSON when combined with --json", Commands = Set(VerboseQueryCommands.Concat(new[] { "index" }).ToArray()) },
+            new() { Name = "--notify", ValuePlaceholder = "<auto|bell|osc9|desktop|none>", Description = "Signal long index completion; desktop currently emits OSC 9 terminal notification", Commands = Set("index") },
             new() { Name = "--slow-query-ms", ValuePlaceholder = "<n>", Description = "Log profiled SQL statements at or above this millisecond threshold", Commands = Set(ProfileCommands) },
             new() { Name = "--trace", ValuePlaceholder = "<none|stderr|file>", Description = "Emit one structured JSON query trace line to stderr or a daily log file", Commands = Set(TraceCommands) },
             new() { Name = "--limit", ValuePlaceholder = "<n>", Description = "Max results", Commands = Set(LimitCapableCommands) },

src/CodeIndex/Cli/ConsoleUi.cs

@@ -50,6 +50,14 @@ public enum DurationOutputFormat
     Hms = 2,
 }
 
+public enum CompletionNotificationMode
+{
+    Auto = 0,
+    None = 1,
+    Bell = 2,
+    Osc9 = 3,
+}
+
 /// <summary>
 /// Console UI helpers: spinner, progress bar, banner, and easter egg messages.
 /// コンソールUIヘルパー: スピナー、プログレスバー、バナー、イースターエッグメッセージ。
@@ -60,7 +68,7 @@ public static class ConsoleUi
 
     private static readonly (string Command, string Usage)[] CommandUsageLines =
     [
-        ("index", "cdidx index <projectPath> [--db <path>] [--rebuild] [--optimize] [--verbose] [--dry-run] [--force] [--quiet] [--json] [--memory-trace] [--duration-format <auto|seconds|hms>] [--max-file-bytes <bytes>] [--follow-symlinks <none|internal|all>] [--include-symbol-kind <kind>[,<kind>]] [--exclude-symbol-kind <kind>[,<kind>]] [--watch [--debounce <ms>]]"),
+        ("index", "cdidx index <projectPath> [--db <path>] [--rebuild] [--optimize] [--verbose] [--dry-run] [--force] [--quiet] [--json] [--memory-trace] [--duration-format <auto|seconds|hms>] [--notify <auto|bell|osc9|desktop|none>] [--max-file-bytes <bytes>] [--follow-symlinks <none|internal|all>] [--include-symbol-kind <kind>[,<kind>]] [--exclude-symbol-kind <kind>[,<kind>]] [--watch [--debounce <ms>]]"),
         ("hooks", "cdidx hooks <install|uninstall|status> [--project <path>] [--force] [--json]"),
         ("backfill-fold", "cdidx backfill-fold [--db <path>] [--dry-run] [--json]"),
         ("optimize", "cdidx optimize [--db <path>] [--json]"),
@@ -130,6 +138,12 @@ internal static string Counted(int count, string singular, string? plural = null
         return $"{formatted} {(count == 1 ? singular : plural ?? singular + "s")}";
     }
 
+    internal static string FormatNumber(long value, string format = "N0")
+        => value.ToString(format, CultureInfo.InvariantCulture);
+
+    internal static string FormatNumber(int value, string format = "N0")
+        => value.ToString(format, CultureInfo.InvariantCulture);
+
     internal static string FoundSummary(int count, string singular, string? plural = null)
     {
         plural ??= singular + "s";
@@ -367,6 +381,9 @@ public static string[] GetSpinnerFrames(string? easterEgg)
     // Track last progress line length for clearing / クリア用に最後のプログレス行の長さを記録
     private static int _lastProgressLineLength;
     private static bool _asciiOutputForced;
+    private static bool _widthDetectionFailed;
+    private static bool _widthDetectionTraceWritten;
+    private static bool _traceWidthDetectionFailures;
 
     /// <summary>
     /// Set progress bar spinner theme (reuses GetSpinnerFrames).
@@ -424,7 +441,9 @@ internal static string FormatProgressLine(int current, int total, int windowWidt
     {
         const int barWidth = 32;
         var pct = (double)current / total;
-        var percentAndCounts = $"{pct * 100,5:F1}%  [{current:N0}/{total:N0}]";
+        var percentAndCounts = string.Create(
+            CultureInfo.InvariantCulture,
+            $"{pct * 100,5:F1}%  [{current:N0}/{total:N0}]");
 
         if (useUnicodeGlyphs && windowWidth < 40)
             return percentAndCounts;
@@ -507,6 +526,55 @@ public static void PrintBanner()
         Console.WriteLine(banner);
     }
 
+    public static void PrintIndexCompleteSummary(
+        string projectRoot,
+        string resolvedDbPath,
+        bool incremental,
+        int filesScanned,
+        IReadOnlyDictionary<string, int> languageCounts)
+    {
+        Console.WriteLine(incremental ? "Next steps (incremental):" : "Next steps:");
+        Console.WriteLine("  - Search code: cdidx search \"authenticate\" --path src/");
+        Console.WriteLine("  - Find a definition: cdidx definition SymbolName");
+        Console.WriteLine($"  - Start MCP: cdidx mcp --db {QuoteForDisplay(resolvedDbPath)}");
+        Console.WriteLine($"  - Database: {resolvedDbPath}");
+        Console.WriteLine("  - Exclude paths with .gitignore or .cdidxignore, then rerun cdidx index .");
+        Console.WriteLine($"  - Scanned {Counted(filesScanned, "file", format: "N0")} under {projectRoot}");
+        if (languageCounts.Count > 0)
+        {
+            var summary = string.Join(
+                ", ",
+                languageCounts
+                    .OrderByDescending(static pair => pair.Value)
+                    .ThenBy(static pair => pair.Key, StringComparer.Ordinal)
+                    .Take(6)
+                    .Select(static pair => $"{pair.Key} {pair.Value.ToString("N0", CultureInfo.InvariantCulture)}"));
+            Console.WriteLine($"  - Languages: {summary}");
+        }
+        Console.WriteLine();
+    }
+
+    public static void EmitCompletionNotification(CompletionNotificationMode mode, string message)
+    {
+        var resolved = mode == CompletionNotificationMode.Auto
+            ? ShouldUseInteractiveConsole() ? CompletionNotificationMode.Bell : CompletionNotificationMode.None
+            : mode;
+        if (resolved == CompletionNotificationMode.None)
+            return;
+
+        var safeMessage = message.Replace('\r', ' ').Replace('\n', ' ');
+        if (resolved == CompletionNotificationMode.Osc9)
+            Console.Error.Write($"\u001b]9;{safeMessage}\a");
+        else
+            Console.Error.Write('\a');
+        Console.Error.Flush();
+    }
+
+    private static string QuoteForDisplay(string value)
+        => value.IndexOfAny([' ', '\t', '"']) < 0
+            ? value
+            : $"\"{value.Replace("\"", "\\\"", StringComparison.Ordinal)}\"";
+
     // --- Easter eggs / イースターエッグ ---
 
     /// <summary>
@@ -799,6 +867,7 @@ private static void PrintFlagReference(Action<string> WriteHelpLine)
         Console.WriteLine("  --memory-trace             Include phase memory samples in index JSON output");
         Console.WriteLine("  --quiet, -q, --silent      Suppress informational stderr output; errors still print (also honors CDIDX_QUIET=1)");
         Console.WriteLine("  --duration-format <format> Index elapsed time format: `auto` (default), `seconds`, or `hms`; JSON keeps raw elapsed_ms");
+        WriteHelpLine("  --notify <mode>           Long index completion signal: auto, bell, osc9, desktop, or none (also honors CDIDX_NOTIFY; quiet/json suppress it)");
         WriteHelpLine("  --max-file-bytes <bytes>  Index only files up to this size (default: 4MiB; also honors CDIDX_MAX_FILE_BYTES; accepts K/M/G suffixes)");
         WriteHelpLine("  --parallelism <n>         Full-scan extraction workers (default: CPU count capped at 16; also honors CDIDX_INDEX_PARALLELISM)");
         WriteHelpLine("  --follow-symlinks <mode>  Directory symlink policy: none (default), internal, or all");
@@ -2027,6 +2096,10 @@ private static bool IsUnicodeLocale(string locale)
 
     internal static bool IsAsciiOutputForced() => _asciiOutputForced;
 
+    internal static bool WidthDetectionFailed => _widthDetectionFailed;
+
+    internal static void SetWidthDetectionTracing(bool enabled) => _traceWidthDetectionFailures = enabled;
+
     /// <summary>
     /// Get console window width safely (some environments throw IOException).
     /// コンソール幅を安全に取得する（一部環境ではIOExceptionが発生する）。
@@ -2039,12 +2112,32 @@ internal static int GetWindowWidth()
         try
         {
             var w = Console.WindowWidth;
-            return w > 0 ? w : 80;
+            if (w > 0)
+                return w;
+        }
+        catch (IOException ex)
+        {
+            return GetFallbackWindowWidth(ex);
         }
-        catch
+        catch (NotSupportedException ex)
         {
-            return 80;
+            return GetFallbackWindowWidth(ex);
         }
+
+        return GetFallbackWindowWidth(null);
+    }
+
+    private static int GetFallbackWindowWidth(Exception? exception)
+    {
+        _widthDetectionFailed = true;
+        if (_traceWidthDetectionFailures && !_widthDetectionTraceWritten)
+        {
+            var suffix = exception == null ? string.Empty : $" ({exception.GetType().Name}: {exception.Message})";
+            Console.Error.WriteLine($"cdidx: console width detection failed; using COLUMNS or 80 columns{suffix}");
+            _widthDetectionTraceWritten = true;
+        }
+
+        return TryGetColumnsEnvironmentWidth(out var columnsWidth) ? columnsWidth : 80;
     }
 
     private static bool TryGetColumnsEnvironmentWidth(out int width)