diff --git a/CLAUDE.md b/CLAUDE.md
index c172580..0ebb884 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -140,6 +140,15 @@ wenn keines dransteht.
 Anwendung ruft `observe` und `status` nicht auf. Wer den Instanzmanager baut
 (#528, Stufe 3), liest den Befundzustand von Anfang an aus diesem Feld.
 
+## Sprache: Englisch ist die Hauptsprache (seit 2026-09-19, #661)
+
+Neue Module, Klassen, Ansichten und Menüeinträge entstehen **auf Englisch** —
+Bezeichner, Kommentare und Oberflächentexte. Texte stehen nicht fest im Code,
+sondern kommen über Sprachschlüssel aus getrennten Sprachpaketen (WebUI:
+`modules/i18n.js`, Pakete unter `wwwroot/i18n/`). Deutsch ist die erste
+Zusatzsprache. Bestehenden deutschen Code nicht nebenbei umschreiben — die
+Umstellung des Bestands ist ein eigenes Vorhaben mit niedriger Priorität.
+
 ## Weitere Handbücher
 
 | Dokument | Wofür |
diff --git a/Directory.Build.props b/Directory.Build.props
index 87075d5..380b219 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -18,7 +18,7 @@
       ClawdDotNet.Core.BuildInfo bleibt daneben bestehen: das ist ein von Hand
       gefuehrter Zaehler mit Aenderungstext, keine Versionsangabe.
     -->
-    <Version>0.1.11</Version>
+    <Version>0.1.12</Version>
 
     <!--
       Symbole in die Assembly einbetten statt als .pdb daneben zu legen.
diff --git a/src/ClawdDotNet.App/AppHost.cs b/src/ClawdDotNet.App/AppHost.cs
index d3460f5..90d94b6 100644
--- a/src/ClawdDotNet.App/AppHost.cs
+++ b/src/ClawdDotNet.App/AppHost.cs
@@ -98,6 +98,12 @@ public sealed class AppHost : IAsyncDisposable
     public TaskboardService? Board { get; private init; }
     public SqliteUsageRepository? Usage { get; private init; }
 
+    /// <summary>#660: Prompt history - prompt and response of every run.</summary>
+    public Core.Transcripts.IRunTranscriptStore? Transcripts { get; private init; }
+
+    /// <summary>#660: Usage analysis, run details and prompt history for the user interfaces.</summary>
+    public RunInsights? Insights { get; private init; }
+
     /// <summary>Modellpreise von OpenRouter - fuer Budget und Kostenprognose (#595). Laedt im Hintergrund.</summary>
     public ModelPricingCatalog? Pricing { get; private init; }
 
@@ -525,6 +531,7 @@ public sealed class AppHost : IAsyncDisposable
         var dauerfreigaben = new SqliteDauerfreigabeRepository(storage);
         var stagingGate = new StagingGate(new StagingPolicy(), stagingRepository, dauerfreigaben: dauerfreigaben);
         var usage = new SqliteUsageRepository(storage);
+        var transcripts = new Core.Transcripts.SqliteRunTranscriptStore(storage);
 
         // Preise fürs Budget: Ohne sie greift nur die Token-Grenze.
         var pricing = new ModelPricingCatalog();
@@ -539,6 +546,8 @@ public sealed class AppHost : IAsyncDisposable
             memory, usage, pricing, taskRepository, audit, stagingGate)
         {
             InstanceBudget = instance.Budget,
+            TranscriptStore = transcripts,
+            DefaultTranscriptRetention = () => instance.PromptHistory.RetentionDays,
             MaxDelegationDepth = instance.MaxDelegationDepth,
             DelegationGateTimeout = TimeSpan.FromSeconds(instance.DelegationGateTimeoutSeconds)
         };
@@ -574,6 +583,11 @@ public sealed class AppHost : IAsyncDisposable
             Staging = staging,
             Board = board,
             Usage = usage,
+            Transcripts = transcripts,
+            Insights = new RunInsights(audit, transcripts, board, staging,
+                agentId => instance.Agents.FirstOrDefault(a => a.AgentId == agentId) is { } agent
+                    ? engine.TranscriptRetentionFor(agent)
+                    : Core.Transcripts.PromptHistorySettings.Normalize(instance.PromptHistory.RetentionDays)),
             Pricing = pricing,
             TelegramClient = telegram,
             Status = new OpenRouterStatusService(instance.OpenRouterApiKey),
@@ -591,6 +605,16 @@ public sealed class AppHost : IAsyncDisposable
 
         host._shutdown.Add(() => { openRouter.Dispose(); return ValueTask.CompletedTask; });
 
+        // #660: Retention of the prompt history - per agent, falling back to the instance.
+        var janitor = new Core.Transcripts.TranscriptJanitor(
+            transcripts,
+            agentId => instance.Agents.FirstOrDefault(a => a.AgentId == agentId) is { } agent
+                ? engine.TranscriptRetentionFor(agent)
+                : Core.Transcripts.PromptHistorySettings.Normalize(instance.PromptHistory.RetentionDays),
+            loggerFactory.CreateLogger("ClawdDotNet.Core.Transcripts"));
+        janitor.Start();
+        host._shutdown.Add(janitor.DisposeAsync);
+
         // #593: Angelegt wurde der Dienst schon immer, gestartet nie — weder kopflos noch
         // mit Fenster. Die Kopfzeile der Weboberflaeche stand deshalb dauerhaft auf
         // "OpenRouter: —" und /api/status auf "Prüfe…".
diff --git a/src/ClawdDotNet.App/Services/AgentAdministration.cs b/src/ClawdDotNet.App/Services/AgentAdministration.cs
index cfd8b79..877457f 100644
--- a/src/ClawdDotNet.App/Services/AgentAdministration.cs
+++ b/src/ClawdDotNet.App/Services/AgentAdministration.cs
@@ -241,6 +241,37 @@ public sealed class AgentAdministration(AppHost host)
         return AdminResult.Success($"Rechte für '{toolName}' ({agent.DisplayName}) gespeichert.");
     }
 
+    /// <summary>
+    /// #660: Sets how long the prompt history of an agent is kept, in days
+    /// (0 = never record, -1 = forever, <c>null</c> = instance default).
+    /// </summary>
+    public AdminResult SetPromptHistoryRetention(string agentId, int? retentionDays)
+    {
+        if (Find(agentId) is not { } agent)
+            return AdminResult.Failure($"No agent with id '{agentId}'.");
+
+        agent.PromptHistory.RetentionDays = retentionDays is { } d
+            ? Core.Transcripts.PromptHistorySettings.Normalize(d)
+            : null;
+
+        PersistAgent(agent);
+        host.SaveInstance(new InstanceChange(InstanceChangeKind.Agents, agentId));
+
+        return AdminResult.Success(retentionDays is null
+            ? $"Prompt history of '{agent.DisplayName}' follows the instance default."
+            : $"Prompt history of '{agent.DisplayName}': {Core.Transcripts.PromptHistorySettings.Describe(retentionDays.Value)}.");
+    }
+
+    /// <summary>#660: Instance default retention of the prompt history, in days.</summary>
+    public AdminResult SetDefaultPromptHistoryRetention(int retentionDays)
+    {
+        host.Instance.PromptHistory.RetentionDays = Core.Transcripts.PromptHistorySettings.Normalize(retentionDays);
+        host.SaveInstance(new InstanceChange(InstanceChangeKind.Settings));
+
+        return AdminResult.Success(
+            $"Prompt history default: {Core.Transcripts.PromptHistorySettings.Describe(retentionDays)}.");
+    }
+
     public AdminResult SetToolSettings(
         string agentId, string toolName, Dictionary<string, object?> settings)
     {
diff --git a/src/ClawdDotNet.App/Services/RunInsights.cs b/src/ClawdDotNet.App/Services/RunInsights.cs
new file mode 100644
index 0000000..670a6c3
--- /dev/null
+++ b/src/ClawdDotNet.App/Services/RunInsights.cs
@@ -0,0 +1,71 @@
+using ClawdDotNet.Core.Analytics;
+using ClawdDotNet.Core.Audit;
+using ClawdDotNet.Core.Staging;
+using ClawdDotNet.Core.Tasks;
+using ClawdDotNet.Core.Transcripts;
+
+namespace ClawdDotNet.App.Services;
+
+/// <summary>Everything known about a single run (#660).</summary>
+public sealed record RunDetail(
+    string RunId,
+    RunReceipt? Receipt,
+    string? TaskTitle,
+    IReadOnlyList<AuditEntry> ToolCalls,
+    IReadOnlyList<StagedCall> Approvals,
+    RunTranscript? Transcript,
+    string? SystemPrompt,
+    string TranscriptState);
+
+/// <summary>
+/// Read side of the usage analysis and the prompt history (#660) for both user interfaces.
+/// Owns no data: receipts and audit come from the audit repository, transcripts from the
+/// transcript store, task titles from the board.
+/// </summary>
+public sealed class RunInsights(
+    IAuditRepository audit,
+    IRunTranscriptStore? transcripts,
+    TaskboardService? board,
+    StagingService? staging,
+    Func<string, int> retentionFor)
+{
+    public UsageAnalytics Analytics { get; } = new(audit, board is null
+        ? null
+        : async (id, ct) => (await board.GetAsync(id, ct))?.Title);
+
+    public IRunTranscriptStore? Transcripts => transcripts;
+
+    public async Task<RunDetail?> GetRunAsync(string runId, CancellationToken ct)
+    {
+        var receipt = await audit.GetReceiptForRunAsync(runId, ct);
+        var calls = await audit.ListForRunAsync(runId, ct);
+        var transcript = transcripts is null ? null : await transcripts.GetAsync(runId, ct);
+
+        if (receipt is null && calls.Count == 0 && transcript is null)
+            return null;
+
+        var agentId = receipt?.AgentId ?? transcript?.AgentId ?? calls.FirstOrDefault()?.AgentId ?? "";
+        var taskId = receipt?.TaskId ?? transcript?.TaskId;
+
+        return new RunDetail(
+            runId,
+            receipt,
+            taskId is not null && board is not null ? (await board.GetAsync(taskId, ct))?.Title : null,
+            // Only the completed calls; the "started" markers (#554) would double every line.
+            calls.Where(c => c.Status != AuditStatus.Started).ToList(),
+            staging is null ? [] : await staging.ListForRunAsync(runId, ct),
+            transcript,
+            transcript?.SystemPromptHash is { } hash && transcripts is not null
+                ? await transcripts.GetSystemPromptAsync(hash, ct)
+                : null,
+            TranscriptState(transcript, agentId));
+    }
+
+    /// <summary>Why there is or is not a transcript - the UI says it instead of showing an empty box.</summary>
+    private string TranscriptState(RunTranscript? transcript, string agentId)
+    {
+        if (transcript is not null) return "recorded";
+        if (transcripts is null) return "unavailable";
+        return retentionFor(agentId) == PromptHistorySettings.Never ? "disabled" : "missing";
+    }
+}
diff --git a/src/ClawdDotNet.Core/Analytics/UsageAnalytics.cs b/src/ClawdDotNet.Core/Analytics/UsageAnalytics.cs
new file mode 100644
index 0000000..953d188
--- /dev/null
+++ b/src/ClawdDotNet.Core/Analytics/UsageAnalytics.cs
@@ -0,0 +1,224 @@
+using ClawdDotNet.Core.Audit;
+
+namespace ClawdDotNet.Core.Analytics;
+
+/// <summary>Filter, sort order and page of <see cref="UsageAnalytics.QueryRunsAsync"/>.</summary>
+public sealed record RunQuery
+{
+    public DateTime FromUtc { get; init; }
+    public DateTime ToUtc { get; init; }
+    public IReadOnlyCollection<string> Agents { get; init; } = [];
+    public IReadOnlyCollection<string> Models { get; init; } = [];
+    public IReadOnlyCollection<string> Sources { get; init; } = [];
+    public IReadOnlyCollection<string> Statuses { get; init; } = [];
+    public decimal? MinCostUsd { get; init; }
+
+    /// <summary>Free text over run id, agent, model, task id, task title and result.</summary>
+    public string? Search { get; init; }
+
+    /// <summary>time, agent, model, source, status, steps, prompt, completion, tokens, cost, duration.</summary>
+    public string Sort { get; init; } = "time";
+    public bool Descending { get; init; } = true;
+    public int Offset { get; init; }
+    public int Limit { get; init; } = 50;
+}
+
+public sealed record RunRow(RunReceipt Receipt, string? TaskTitle)
+{
+    public int TotalTokens => Receipt.PromptTokens + Receipt.CompletionTokens;
+}
+
+/// <summary>Sums over the whole filter, not only the current page.</summary>
+public sealed record RunTotals(
+    int Runs, long PromptTokens, long CompletionTokens, long CachedTokens,
+    decimal CostUsd, int RunsWithUnknownCost, int NotRun);
+
+public sealed record RunPage(IReadOnlyList<RunRow> Items, int Total, RunTotals Totals);
+
+/// <summary>One stacked bar segment: <see cref="Group"/> within the bucket starting at <see cref="BucketStart"/>.</summary>
+public sealed record SeriesPoint(DateTime BucketStart, string Group, int Runs, long Tokens, decimal CostUsd);
+
+/// <summary>Something worth a marker on the time axis.</summary>
+public sealed record UsageEvent(DateTime At, string Kind, string AgentId, string Text);
+
+/// <summary>Values that occur in the range - the options of the filter dropdowns.</summary>
+public sealed record UsageFacets(
+    IReadOnlyList<string> Agents, IReadOnlyList<string> Models,
+    IReadOnlyList<string> Sources, IReadOnlyList<string> Statuses);
+
+/// <summary>
+/// Usage analysis over run receipts (#660). Receipts rather than RunUsage: only they carry
+/// run id, source, task and the runs that never happened (budget denials, #608).
+///
+/// <para>Filtering, sorting and bucketing happen in memory over the receipts of the
+/// requested range. That keeps every rule in one testable place; the volume of a single
+/// instance (a few hundred runs a day) is far below where this would matter. The range is
+/// capped at <see cref="MaxReceipts"/> receipts.</para>
+/// </summary>
+public sealed class UsageAnalytics(
+    IAuditRepository audit,
+    Func<string, CancellationToken, Task<string?>>? taskTitle = null)
+{
+    public const int MaxReceipts = 50_000;
+
+    /// <summary>Statuses of runs that were refused before any model call.</summary>
+    private static readonly HashSet<string> NotRunStatuses =
+        new(StringComparer.OrdinalIgnoreCase) { "BudgetExceeded", "ShuttingDown", "TargetBusy" };
+
+    public async Task<RunPage> QueryRunsAsync(RunQuery q, CancellationToken ct)
+    {
+        var rows = await LoadAsync(q.FromUtc, q.ToUtc, ct);
+        var filtered = rows.Where(r => Matches(r, q)).ToList();
+
+        var totals = new RunTotals(
+            filtered.Count,
+            filtered.Sum(r => (long)r.Receipt.PromptTokens),
+            filtered.Sum(r => (long)r.Receipt.CompletionTokens),
+            filtered.Sum(r => (long)r.Receipt.CachedTokens),
+            filtered.Sum(r => r.Receipt.CostUsd),
+            filtered.Count(r => !r.Receipt.CostIsKnown && !NotRunStatuses.Contains(r.Receipt.Status)),
+            filtered.Count(r => NotRunStatuses.Contains(r.Receipt.Status)));
+
+        var page = Sort(filtered, q.Sort, q.Descending)
+            .Skip(Math.Max(0, q.Offset))
+            .Take(Math.Clamp(q.Limit, 1, 500))
+            .ToList();
+
+        return new RunPage(page, filtered.Count, totals);
+    }
+
+    /// <param name="bucket"><c>hour</c> or <c>day</c>.</param>
+    /// <param name="groupBy"><c>agent</c>, <c>model</c> or <c>source</c>.</param>
+    /// <param name="utcOffset">Offset of the viewer's local time - a "day" is the viewer's day.</param>
+    public async Task<IReadOnlyList<SeriesPoint>> SeriesAsync(
+        RunQuery q, string bucket, string groupBy, TimeSpan utcOffset, CancellationToken ct)
+    {
+        var rows = (await LoadAsync(q.FromUtc, q.ToUtc, ct)).Where(r => Matches(r, q));
+
+        return rows
+            .GroupBy(r => (Start: BucketStart(r.Receipt.OccurredAt, bucket, utcOffset), Group: GroupKey(r.Receipt, groupBy)))
+            .Select(g => new SeriesPoint(
+                g.Key.Start, g.Key.Group, g.Count(),
+                g.Sum(r => (long)r.TotalTokens), g.Sum(r => r.Receipt.CostUsd)))
+            .OrderBy(p => p.BucketStart).ThenBy(p => p.Group, StringComparer.Ordinal)
+            .ToList();
+    }
+
+    /// <summary>Budget denials and model changes - the usual explanation for a jump in a chart.</summary>
+    public async Task<IReadOnlyList<UsageEvent>> EventsAsync(DateTime fromUtc, DateTime toUtc, CancellationToken ct)
+    {
+        var rows = await LoadAsync(fromUtc, toUtc, ct);
+        var events = new List<UsageEvent>();
+
+        // One marker per agent and hour is enough for a denial streak.
+        foreach (var g in rows.Where(r => r.Receipt.Status == "BudgetExceeded")
+                     .GroupBy(r => (r.Receipt.AgentId, Hour: Truncate(r.Receipt.OccurredAt, TimeSpan.FromHours(1)))))
+        {
+            events.Add(new UsageEvent(g.Min(r => r.Receipt.OccurredAt), "budget_exceeded", g.Key.AgentId,
+                $"{g.Count()} run(s) refused: daily budget exhausted"));
+        }
+
+        foreach (var agent in rows.GroupBy(r => r.Receipt.AgentId))
+        {
+            string? previous = null;
+            foreach (var r in agent.Where(r => !string.IsNullOrWhiteSpace(r.Receipt.Model)))
+            {
+                if (previous is not null && previous != r.Receipt.Model)
+                    events.Add(new UsageEvent(r.Receipt.OccurredAt, "model_changed", agent.Key,
+                        $"{previous} → {r.Receipt.Model}"));
+                previous = r.Receipt.Model;
+            }
+        }
+
+        return events.OrderBy(e => e.At).ToList();
+    }
+
+    public async Task<UsageFacets> FacetsAsync(DateTime fromUtc, DateTime toUtc, CancellationToken ct)
+    {
+        var rows = await LoadAsync(fromUtc, toUtc, ct);
+        static IReadOnlyList<string> Distinct(IEnumerable<string> values)
+            => values.Where(v => !string.IsNullOrWhiteSpace(v)).Distinct().Order(StringComparer.Ordinal).ToList();
+
+        return new UsageFacets(
+            Distinct(rows.Select(r => r.Receipt.AgentId)),
+            Distinct(rows.Select(r => r.Receipt.Model)),
+            Distinct(rows.Select(r => r.Receipt.Source)),
+            Distinct(rows.Select(r => r.Receipt.Status)));
+    }
+
+    // ─── Building blocks ───
+
+    private async Task<IReadOnlyList<RunRow>> LoadAsync(DateTime fromUtc, DateTime toUtc, CancellationToken ct)
+    {
+        var receipts = await audit.ListReceiptsAsync(fromUtc, toUtc, MaxReceipts, ct);
+        if (taskTitle is null)
+            return receipts.Select(r => new RunRow(r, null)).ToList();
+
+        var titles = new Dictionary<string, string?>();
+        foreach (var id in receipts.Select(r => r.TaskId).OfType<string>().Distinct())
+            titles[id] = await taskTitle(id, ct);
+
+        return receipts.Select(r => new RunRow(r, r.TaskId is { } id ? titles.GetValueOrDefault(id) : null)).ToList();
+    }
+
+    internal static bool Matches(RunRow row, RunQuery q)
+    {
+        var r = row.Receipt;
+        if (q.Agents.Count > 0 && !q.Agents.Contains(r.AgentId)) return false;
+        if (q.Models.Count > 0 && !q.Models.Contains(r.Model)) return false;
+        if (q.Sources.Count > 0 && !q.Sources.Contains(r.Source)) return false;
+        if (q.Statuses.Count > 0 && !q.Statuses.Contains(r.Status)) return false;
+        if (q.MinCostUsd is { } min && r.CostUsd < min) return false;
+
+        if (!string.IsNullOrWhiteSpace(q.Search))
+        {
+            var s = q.Search.Trim();
+            bool Has(string? v) => v?.Contains(s, StringComparison.OrdinalIgnoreCase) == true;
+            if (!(Has(r.RunId) || Has(r.AgentId) || Has(r.Model) || Has(r.TaskId) || Has(row.TaskTitle) || Has(r.ResultRef)))
+                return false;
+        }
+        return true;
+    }
+
+    private static IEnumerable<RunRow> Sort(IEnumerable<RunRow> rows, string sort, bool descending)
+    {
+        Func<RunRow, IComparable> key = (sort ?? "time").ToLowerInvariant() switch
+        {
+            "agent" => r => r.Receipt.AgentId,
+            "model" => r => r.Receipt.Model,
+            "source" => r => r.Receipt.Source,
+            "status" => r => r.Receipt.Status,
+            "steps" => r => r.Receipt.StepCount,
+            "prompt" => r => r.Receipt.PromptTokens,
+            "completion" => r => r.Receipt.CompletionTokens,
+            "tokens" => r => r.TotalTokens,
+            "cost" => r => r.Receipt.CostUsd,
+            "duration" => r => r.Receipt.DurationMs,
+            _ => r => r.Receipt.OccurredAt
+        };
+
+        // Newest first as the tie-breaker, whatever the primary order.
+        return descending
+            ? rows.OrderByDescending(key).ThenByDescending(r => r.Receipt.OccurredAt)
+            : rows.OrderBy(key).ThenByDescending(r => r.Receipt.OccurredAt);
+    }
+
+    internal static DateTime BucketStart(DateTime occurredUtc, string bucket, TimeSpan utcOffset)
+    {
+        var local = DateTime.SpecifyKind(occurredUtc, DateTimeKind.Utc) + utcOffset;
+        var start = bucket == "day"
+            ? local.Date
+            : new DateTime(local.Year, local.Month, local.Day, local.Hour, 0, 0);
+        return DateTime.SpecifyKind(start - utcOffset, DateTimeKind.Utc);
+    }
+
+    private static string GroupKey(RunReceipt r, string groupBy) => groupBy switch
+    {
+        "model" => string.IsNullOrWhiteSpace(r.Model) ? "(unknown)" : r.Model,
+        "source" => r.Source,
+        _ => r.AgentId
+    };
+
+    private static DateTime Truncate(DateTime value, TimeSpan unit)
+        => new(value.Ticks - value.Ticks % unit.Ticks, value.Kind);
+}
diff --git a/src/ClawdDotNet.Core/Audit/IAuditRepository.cs b/src/ClawdDotNet.Core/Audit/IAuditRepository.cs
index d4fe01e..9389733 100644
--- a/src/ClawdDotNet.Core/Audit/IAuditRepository.cs
+++ b/src/ClawdDotNet.Core/Audit/IAuditRepository.cs
@@ -24,6 +24,12 @@ public interface IAuditRepository
     /// <summary>Alle Belege zu einem Task — die Kosten pro Ergebnis (C7).</summary>
     Task<IReadOnlyList<RunReceipt>> ListReceiptsForTaskAsync(string taskId, CancellationToken ct);
 
+    /// <summary>
+    /// #660: All receipts in <c>[fromUtc, toUtc)</c>, oldest first, at most
+    /// <paramref name="limit"/> - the input of the usage analysis.
+    /// </summary>
+    Task<IReadOnlyList<RunReceipt>> ListReceiptsAsync(DateTime fromUtc, DateTime toUtc, int limit, CancellationToken ct);
+
     /// <summary>Zahl der Log-Einträge insgesamt.</summary>
     Task<int> CountAsync(CancellationToken ct);
 
diff --git a/src/ClawdDotNet.Core/Audit/SqliteAuditRepository.cs b/src/ClawdDotNet.Core/Audit/SqliteAuditRepository.cs
index 1dc9011..d53d7e3 100644
--- a/src/ClawdDotNet.Core/Audit/SqliteAuditRepository.cs
+++ b/src/ClawdDotNet.Core/Audit/SqliteAuditRepository.cs
@@ -99,6 +99,24 @@ public sealed class SqliteAuditRepository : IAuditRepository
         return await reader.ReadAsync(ct) ? ReadReceipt(reader) : null;
     }
 
+    public async Task<IReadOnlyList<RunReceipt>> ListReceiptsAsync(DateTime fromUtc, DateTime toUtc, int limit, CancellationToken ct)
+    {
+        await using var conn = await _storage.OpenConnectionAsync(ct);
+        using var cmd = conn.CreateCommand();
+        // OccurredAt is ISO-8601 UTC ("O"), so the text comparison is a time comparison.
+        cmd.CommandText = "SELECT " + ReceiptColumns +
+                          " FROM RunReceipts WHERE OccurredAt >= @from AND OccurredAt < @to ORDER BY OccurredAt LIMIT @limit";
+        cmd.Parameters.AddWithValue("@from", Format(fromUtc));
+        cmd.Parameters.AddWithValue("@to", Format(toUtc));
+        cmd.Parameters.AddWithValue("@limit", limit);
+
+        var results = new List<RunReceipt>();
+        await using var reader = await cmd.ExecuteReaderAsync(ct);
+        while (await reader.ReadAsync(ct))
+            results.Add(ReadReceipt(reader));
+        return results;
+    }
+
     public async Task<IReadOnlyList<RunReceipt>> ListReceiptsForTaskAsync(string taskId, CancellationToken ct)
     {
         await using var conn = await _storage.OpenConnectionAsync(ct);
diff --git a/src/ClawdDotNet.Core/Config/AgentConfig.cs b/src/ClawdDotNet.Core/Config/AgentConfig.cs
index c45894c..c851282 100644
--- a/src/ClawdDotNet.Core/Config/AgentConfig.cs
+++ b/src/ClawdDotNet.Core/Config/AgentConfig.cs
@@ -145,6 +145,12 @@ public sealed class AgentConfig
     [JsonPropertyName("budget")]
     public AgentBudget Budget { get; set; } = new();
 
+    /// <summary>
+    /// #660: Per-agent retention of the prompt history. <c>null</c> retention = instance default.
+    /// </summary>
+    [JsonPropertyName("promptHistory")]
+    public Transcripts.AgentPromptHistorySettings PromptHistory { get; set; } = new();
+
     /// <summary>
     /// Übersetzt <see cref="ReasoningEffort"/> in das Anfragefeld. Null heißt:
     /// nichts mitschicken, das Modell denkt wie voreingestellt.
diff --git a/src/ClawdDotNet.Core/Config/InstanceConfig.cs b/src/ClawdDotNet.Core/Config/InstanceConfig.cs
index 8760207..b7357e6 100644
--- a/src/ClawdDotNet.Core/Config/InstanceConfig.cs
+++ b/src/ClawdDotNet.Core/Config/InstanceConfig.cs
@@ -124,6 +124,13 @@ public sealed class InstanceConfig
     [JsonPropertyName("budget")]
     public InstanceBudget Budget { get; set; } = new();
 
+    /// <summary>
+    /// #660: How long prompt and response of every run are kept. Default for all agents;
+    /// each agent can override it.
+    /// </summary>
+    [JsonPropertyName("promptHistory")]
+    public Transcripts.PromptHistorySettings PromptHistory { get; set; } = new();
+
     /// <summary>
     /// Wie viele Weitergaben eine Delegationskette höchstens haben darf (B8, #206).
     /// A→B ist die Tiefe 1. Zyklen fängt die Kette selbst ab; dieser Wert begrenzt die
diff --git a/src/ClawdDotNet.Core/Engine/AgentEngine.cs b/src/ClawdDotNet.Core/Engine/AgentEngine.cs
index bbf96a7..33d2ed7 100644
--- a/src/ClawdDotNet.Core/Engine/AgentEngine.cs
+++ b/src/ClawdDotNet.Core/Engine/AgentEngine.cs
@@ -127,6 +127,15 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
 
     public event Action<string, string>? OnStepCompleted;
 
+    /// <summary>#660: Where prompt and response of every run are kept. <c>null</c> = not at all.</summary>
+    public Transcripts.IRunTranscriptStore? TranscriptStore { get; init; }
+
+    /// <summary>
+    /// #660: Instance-wide retention in days (0 = never, -1 = forever). A function, so a
+    /// changed setting applies to the next run without a restart.
+    /// </summary>
+    public Func<int> DefaultTranscriptRetention { get; init; } = () => Transcripts.PromptHistorySettings.DefaultRetentionDays;
+
     /// <summary>
     /// Wird ausgelöst wenn ein neuer ChatEntry hinzugefügt wird (agentId, role, content, source).
     /// Erlaubt der UI, Nachrichten aus Hintergrund-Runs (ToolJobs, AgentComm) live anzuzeigen.
@@ -161,9 +170,11 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
 
         var runId = Guid.NewGuid().ToString("N");
         var chain = delegation ?? DelegationChain.Root(agentConfig.AgentId);
-        var result = await RunCoreAsync(agentConfig, userMessage, instanceId, externalCt, runId, source, chain);
+        var recorder = CreateRecorder(agentConfig);
+        var result = await RunCoreAsync(agentConfig, userMessage, instanceId, externalCt, runId, source, chain, recorder);
         await RecordUsageAsync(agentConfig, result);
         await RecordReceiptAsync(runId, agentConfig, result, source ?? AuditSource.Direct, taskId);
+        await SaveTranscriptAsync(recorder, runId, agentConfig, result, source ?? AuditSource.Direct, taskId);
         return result;
     }
 
@@ -174,7 +185,8 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
         CancellationToken externalCt,
         string runId,
         string? source,
-        DelegationChain chain)
+        DelegationChain chain,
+        Transcripts.RunTranscriptRecorder recorder)
     {
         var logger = _loggerFactory.CreateLogger($"ClawdDotNet.Core.Engine.{agentConfig.AgentId}");
         var loopGuard = new LoopGuard(agentConfig.LoopGuard);
@@ -205,6 +217,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                 messages.Add(ChatMessage.System(systemPrompt));
 
             messages.Add(ChatMessage.User(MitZeit(userMessage, source)));
+            recorder.Begin(systemPrompt, messages[^1].Content?.ToString() ?? userMessage);
 
             string? finalMessage = null;
             var truncated = false;
@@ -229,6 +242,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                 // sie bezahlt ist statt danach.
                 if (await _compactor.CompactIfNeededAsync(messages, agentConfig.LoopGuard, agentConfig.Model, ct, tally.Add))
                 {
+                    recorder.Event("Context compacted");
                     OnStepCompleted?.Invoke(agentConfig.AgentId, "Context kompaktiert (RunAsync)");
                 }
 
@@ -249,6 +263,8 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                 }
 
                 var choice = response.Choices.FirstOrDefault();
+                if (choice is not null)
+                    recorder.ModelStep(choice.Message, response.Usage, choice.FinishReason);
                 if (choice is null)
                 {
                     finalMessage = "[No response from model]";
@@ -284,6 +300,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                     finally
                     {
                         AppendToolResponses(messages, assistantMessage.ToolCalls, toolResults);
+                        recorder.ToolResults(assistantMessage.ToolCalls, toolResults);
                     }
 
                     if (abbruch is not null)
@@ -304,6 +321,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                         logger.LogWarning("Leere Antwort von {AgentId} nach {Steps} Schritten - einmal nachgefasst",
                             agentConfig.AgentId, loopGuard.Steps);
                         messages.Add(ChatMessage.User(LaufAbschluss.LeerNachfrage));
+                        recorder.EngineNote(LaufAbschluss.LeerNachfrage);
                         continue;
                     }
 
@@ -314,6 +332,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                             agentConfig.AgentId);
                         messages.Add(ChatMessage.Assistant(text));
                         messages.Add(ChatMessage.User(LaufAbschluss.ErgebnisNachfrage));
+                        recorder.EngineNote(LaufAbschluss.ErgebnisNachfrage);
                         continue;
                     }
 
@@ -468,9 +487,11 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
 
         try
         {
-            var result = await ChatCoreAsync(agentConfig, userMessage, instanceId, runCts.Token, source, runId, chain);
+            var recorder = CreateRecorder(agentConfig);
+            var result = await ChatCoreAsync(agentConfig, userMessage, instanceId, runCts.Token, source, runId, chain, recorder);
             await RecordUsageAsync(agentConfig, result);
             await RecordReceiptAsync(runId, agentConfig, result, source, taskId);
+            await SaveTranscriptAsync(recorder, runId, agentConfig, result, source ?? AuditSource.Direct, taskId);
             return result;
         }
         finally
@@ -487,7 +508,8 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
         CancellationToken runCt,
         string? source,
         string runId,
-        DelegationChain chain)
+        DelegationChain chain,
+        Transcripts.RunTranscriptRecorder recorder)
     {
         var logger = _loggerFactory.CreateLogger($"ClawdDotNet.Core.Engine.Chat.{agentConfig.AgentId}");
         var loopGuard = new LoopGuard(agentConfig.LoopGuard);
@@ -532,6 +554,9 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
 
             messages.Add(ChatMessage.User(MitZeit(routedMessage, source)));
             AddChatEntry(agentConfig.AgentId, "user", userMessage, source);
+            recorder.Begin(
+                messages.Count > 0 && messages[0].Role == "system" ? messages[0].Content?.ToString() : null,
+                messages[^1].Content?.ToString() ?? userMessage);
 
             string? finalMessage = null;
             var truncated = false;
@@ -557,6 +582,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                 // nächsten Schritt. Genau ein Schritt zu spät, und der teuerste.
                 if (await _compactor.CompactIfNeededAsync(messages, agentConfig.LoopGuard, agentConfig.Model, ct, tally.Add))
                 {
+                    recorder.Event("Context compacted");
                     PersistChatState(agentConfig.AgentId);
                     OnStepCompleted?.Invoke(agentConfig.AgentId, "Context kompaktiert");
                 }
@@ -581,6 +607,8 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                 }
 
                 var choice = response.Choices.FirstOrDefault();
+                if (choice is not null)
+                    recorder.ModelStep(choice.Message, response.Usage, choice.FinishReason);
                 if (choice is null)
                 {
                     finalMessage = "[No response from model]";
@@ -614,6 +642,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                     finally
                     {
                         AppendToolResponses(messages, assistantMessage.ToolCalls, toolResults);
+                        recorder.ToolResults(assistantMessage.ToolCalls, toolResults);
                     }
 
                     if (abbruch is not null)
@@ -636,6 +665,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                         logger.LogWarning("Leere Antwort von {AgentId} nach {Steps} Schritten - einmal nachgefasst",
                             agentConfig.AgentId, loopGuard.Steps);
                         messages.Add(ChatMessage.User(LaufAbschluss.LeerNachfrage));
+                        recorder.EngineNote(LaufAbschluss.LeerNachfrage);
                         continue;
                     }
 
@@ -647,6 +677,7 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
                         messages.Add(ChatMessage.Assistant(text));
                         AddChatEntry(agentConfig.AgentId, "assistant", text, source);
                         messages.Add(ChatMessage.User(LaufAbschluss.ErgebnisNachfrage));
+                        recorder.EngineNote(LaufAbschluss.ErgebnisNachfrage);
                         continue;
                     }
 
@@ -1746,6 +1777,37 @@ public sealed class AgentEngine : IAgentMessageRouter, Staging.IFrozenCallExecut
     /// <summary>
     /// Hält den Abschluss-Beleg eines Laufs fest (Receipt). Best effort, wie beim Audit.
     /// </summary>
+    // ─── Prompt history (#660) ───
+
+    /// <summary>Retention that applies to this agent: its own setting or the instance default.</summary>
+    public int TranscriptRetentionFor(AgentConfig agentConfig)
+        => Transcripts.PromptHistorySettings.Resolve(agentConfig.PromptHistory?.RetentionDays, DefaultTranscriptRetention());
+
+    private Transcripts.RunTranscriptRecorder CreateRecorder(AgentConfig agentConfig)
+        => TranscriptStore is not null && TranscriptRetentionFor(agentConfig) != Transcripts.PromptHistorySettings.Never
+            ? new Transcripts.RunTranscriptRecorder(enabled: true, _clock)
+            : Transcripts.RunTranscriptRecorder.Disabled;
+
+    /// <summary>Best effort: a transcript that cannot be written must not fail the run.</summary>
+    private async Task SaveTranscriptAsync(
+        Transcripts.RunTranscriptRecorder recorder, string runId, AgentConfig agentConfig,
+        AgentRunResult result, string source, string? taskId)
+    {
+        if (!recorder.Enabled || TranscriptStore is null)
+            return;
+
+        try
+        {
+            var transcript = recorder.Build(runId, agentConfig.AgentId, agentConfig.Model, source, taskId, result.Status.ToString());
+            await TranscriptStore.SaveAsync(transcript, recorder.SystemPrompt, CancellationToken.None);
+        }
+        catch (Exception ex)
+        {
+            _loggerFactory.CreateLogger("ClawdDotNet.Core.Engine.Transcripts")
+                .LogWarning(ex, "Transcript of run {RunId} ({AgentId}) could not be stored", runId, agentConfig.AgentId);
+        }
+    }
+
     private async Task RecordReceiptAsync(
         string runId, AgentConfig agentConfig, AgentRunResult result, string? source, string? taskId)
     {
diff --git a/src/ClawdDotNet.Core/Staging/SqliteStagingRepository.cs b/src/ClawdDotNet.Core/Staging/SqliteStagingRepository.cs
index 0b8894d..beebe5b 100644
--- a/src/ClawdDotNet.Core/Staging/SqliteStagingRepository.cs
+++ b/src/ClawdDotNet.Core/Staging/SqliteStagingRepository.cs
@@ -122,6 +122,20 @@ public sealed class SqliteStagingRepository : IStagingRepository
         return results;
     }
 
+    public async Task<IReadOnlyList<StagedCall>> ListForRunAsync(string runId, CancellationToken ct)
+    {
+        await using var conn = await _storage.OpenConnectionAsync(ct);
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = "SELECT " + Columns + " FROM StagedCalls WHERE RunId = @runId ORDER BY Id";
+        cmd.Parameters.AddWithValue("@runId", runId);
+
+        var results = new List<StagedCall>();
+        await using var reader = await cmd.ExecuteReaderAsync(ct);
+        while (await reader.ReadAsync(ct))
+            results.Add(Read(reader));
+        return results;
+    }
+
     public async Task<int> CountExecutedAsync(string agentId, string tool, string? action, DateTime since, CancellationToken ct)
     {
         await using var conn = await _storage.OpenConnectionAsync(ct);
diff --git a/src/ClawdDotNet.Core/Staging/StagingModels.cs b/src/ClawdDotNet.Core/Staging/StagingModels.cs
index ead80e5..95cd25c 100644
--- a/src/ClawdDotNet.Core/Staging/StagingModels.cs
+++ b/src/ClawdDotNet.Core/Staging/StagingModels.cs
@@ -113,4 +113,7 @@ public interface IStagingRepository
     /// ausgefuehrt wurde (#641) - Grundlage fuer den Vorschlag "Gleichartiges kuenftig erlauben".
     /// </summary>
     Task<int> CountExecutedAsync(string agentId, string tool, string? action, DateTime since, CancellationToken ct);
+
+    /// <summary>#660: Everything a run proposed for approval - for the run detail view.</summary>
+    Task<IReadOnlyList<StagedCall>> ListForRunAsync(string runId, CancellationToken ct);
 }
diff --git a/src/ClawdDotNet.Core/Staging/StagingService.cs b/src/ClawdDotNet.Core/Staging/StagingService.cs
index 1b05db0..75325b1 100644
--- a/src/ClawdDotNet.Core/Staging/StagingService.cs
+++ b/src/ClawdDotNet.Core/Staging/StagingService.cs
@@ -93,6 +93,7 @@ public sealed class StagingService
     }
     public Task<StagedCall?> GetAsync(long id, CancellationToken ct) => _repo.GetAsync(id, ct);
     public Task<int> CountPendingAsync(CancellationToken ct) => _repo.CountPendingAsync(ct);
+    public Task<IReadOnlyList<StagedCall>> ListForRunAsync(string runId, CancellationToken ct) => _repo.ListForRunAsync(runId, ct);
 
     // ─── Dauerfreigaben (#641) ───
 
diff --git a/src/ClawdDotNet.Core/Storage/SqliteStorage.cs b/src/ClawdDotNet.Core/Storage/SqliteStorage.cs
index 1da9500..e54e4cb 100644
--- a/src/ClawdDotNet.Core/Storage/SqliteStorage.cs
+++ b/src/ClawdDotNet.Core/Storage/SqliteStorage.cs
@@ -288,6 +288,37 @@ public sealed class SqliteStorage
 
             CREATE INDEX IF NOT EXISTS IX_Dauerfreigaben_Agent
                 ON Dauerfreigaben (AgentId, Tool, Operation);
+
+            -- #660: Prompt history - prompt and response of every run, kept as long as the
+            -- retention of the agent allows. System prompts are stored once per text.
+            CREATE TABLE IF NOT EXISTS RunTranscripts (
+                RunId            TEXT    PRIMARY KEY,
+                AgentId          TEXT    NOT NULL,
+                Model            TEXT    NOT NULL DEFAULT '',
+                Source           TEXT    NOT NULL DEFAULT '',
+                TaskId           TEXT    NULL,
+                StartedAt        TEXT    NOT NULL,
+                CompletedAt      TEXT    NULL,
+                Status           TEXT    NOT NULL DEFAULT '',
+                SystemPromptHash TEXT    NULL,
+                Prompt           TEXT    NOT NULL DEFAULT '',
+                Response         TEXT    NOT NULL DEFAULT '',
+                EntriesJson      TEXT    NOT NULL DEFAULT '[]',
+                SizeChars        INTEGER NOT NULL DEFAULT 0,
+                Truncated        INTEGER NOT NULL DEFAULT 0
+            );
+
+            CREATE INDEX IF NOT EXISTS IX_RunTranscripts_Agent
+                ON RunTranscripts (AgentId, StartedAt);
+
+            CREATE INDEX IF NOT EXISTS IX_RunTranscripts_Started
+                ON RunTranscripts (StartedAt DESC);
+
+            CREATE TABLE IF NOT EXISTS SystemPrompts (
+                Hash        TEXT PRIMARY KEY,
+                Text        TEXT NOT NULL,
+                FirstSeenAt TEXT NOT NULL
+            );
             """;
 
         cmd.ExecuteNonQuery();
diff --git a/src/ClawdDotNet.Core/Transcripts/PromptHistorySettings.cs b/src/ClawdDotNet.Core/Transcripts/PromptHistorySettings.cs
new file mode 100644
index 0000000..2ac003e
--- /dev/null
+++ b/src/ClawdDotNet.Core/Transcripts/PromptHistorySettings.cs
@@ -0,0 +1,49 @@
+using System.Text.Json.Serialization;
+
+namespace ClawdDotNet.Core.Transcripts;
+
+/// <summary>
+/// How long run transcripts (prompt and response of every run) are kept (#660).
+///
+/// <para>One number of days covers the whole range the user asked for:
+/// <see cref="Never"/> (0) records nothing, <see cref="Forever"/> (-1) keeps everything,
+/// any positive value keeps that many days.</para>
+/// </summary>
+public sealed class PromptHistorySettings
+{
+    public const int Never = 0;
+    public const int Forever = -1;
+    public const int DefaultRetentionDays = 14;
+
+    /// <summary>Instance default for all agents without their own setting.</summary>
+    [JsonPropertyName("retentionDays")]
+    public int RetentionDays { get; set; } = DefaultRetentionDays;
+
+    /// <summary>
+    /// The retention that applies to an agent: its own value if set, otherwise the
+    /// instance default. Values below <see cref="Forever"/> are treated as "forever".
+    /// </summary>
+    public static int Resolve(int? agentRetentionDays, int instanceRetentionDays)
+        => Normalize(agentRetentionDays ?? instanceRetentionDays);
+
+    public static int Normalize(int days) => days < Forever ? Forever : days;
+
+    /// <summary>Human readable form for logs and the UI fallback.</summary>
+    public static string Describe(int days) => Normalize(days) switch
+    {
+        Never => "never recorded",
+        Forever => "kept forever",
+        var d => $"kept for {d} day(s)"
+    };
+}
+
+/// <summary>
+/// Per-agent override (#660): debug a single agent over a long period, or switch
+/// recording off completely for an agent that handles sensitive secrets.
+/// </summary>
+public sealed class AgentPromptHistorySettings
+{
+    /// <summary><c>null</c> = use the instance default.</summary>
+    [JsonPropertyName("retentionDays")]
+    public int? RetentionDays { get; set; }
+}
diff --git a/src/ClawdDotNet.Core/Transcripts/RunTranscript.cs b/src/ClawdDotNet.Core/Transcripts/RunTranscript.cs
new file mode 100644
index 0000000..f9ef4ce
--- /dev/null
+++ b/src/ClawdDotNet.Core/Transcripts/RunTranscript.cs
@@ -0,0 +1,103 @@
+namespace ClawdDotNet.Core.Transcripts;
+
+/// <summary>What a transcript entry is.</summary>
+public static class TranscriptEntryKind
+{
+    /// <summary>The task or message the run started with.</summary>
+    public const string User = "user";
+
+    /// <summary>A follow-up the engine itself sent (empty answer, missing result line).</summary>
+    public const string EngineNote = "engine";
+
+    /// <summary>One model response: text and/or tool calls, with the tokens of this step.</summary>
+    public const string Assistant = "assistant";
+
+    /// <summary>The result of one tool call.</summary>
+    public const string ToolResult = "tool_result";
+
+    /// <summary>Something that happened to the context, e.g. compaction.</summary>
+    public const string Event = "event";
+}
+
+/// <summary>One tool call as the model issued it.</summary>
+public sealed record TranscriptToolCall(string Id, string Name, string Arguments);
+
+/// <summary>
+/// One entry of a run transcript. Texts are stored as the model saw or wrote them, after
+/// secret scrubbing and clipping (<see cref="Clipped"/>).
+/// </summary>
+public sealed record TranscriptEntry
+{
+    public string Kind { get; init; } = "";
+    public DateTime At { get; init; }
+    public string? Text { get; init; }
+    public IReadOnlyList<TranscriptToolCall>? ToolCalls { get; init; }
+
+    /// <summary>For <see cref="TranscriptEntryKind.ToolResult"/>: which call and tool.</summary>
+    public string? ToolCallId { get; init; }
+    public string? ToolName { get; init; }
+
+    /// <summary>For <see cref="TranscriptEntryKind.Assistant"/>: usage of this single step.</summary>
+    public int? PromptTokens { get; init; }
+    public int? CompletionTokens { get; init; }
+    public int? CachedTokens { get; init; }
+    public decimal? CostUsd { get; init; }
+    public string? FinishReason { get; init; }
+
+    /// <summary>The text was shortened to stay within the limits.</summary>
+    public bool Clipped { get; init; }
+}
+
+/// <summary>
+/// Prompt and response of one run (#660), joined to receipts and audit via
+/// <see cref="RunId"/>. The system prompt is stored once per distinct text and referenced
+/// by <see cref="SystemPromptHash"/>.
+/// </summary>
+public sealed record RunTranscript
+{
+    public string RunId { get; init; } = "";
+    public string AgentId { get; init; } = "";
+    public string Model { get; init; } = "";
+    public string Source { get; init; } = "";
+    public string? TaskId { get; init; }
+    public DateTime StartedAt { get; init; }
+    public DateTime? CompletedAt { get; init; }
+    public string Status { get; init; } = "";
+    public string? SystemPromptHash { get; init; }
+    public IReadOnlyList<TranscriptEntry> Entries { get; init; } = [];
+
+    /// <summary>Characters stored, after clipping.</summary>
+    public int SizeChars { get; init; }
+
+    /// <summary>The run exceeded the size limit; later entries are shortened or omitted.</summary>
+    public bool Truncated { get; init; }
+}
+
+/// <summary>A transcript without its entries — for lists.</summary>
+public sealed record RunTranscriptSummary(
+    string RunId,
+    string AgentId,
+    string Model,
+    string Source,
+    string? TaskId,
+    DateTime StartedAt,
+    DateTime? CompletedAt,
+    string Status,
+    string Prompt,
+    string Response,
+    int SizeChars,
+    bool Truncated);
+
+/// <summary>Filter for <see cref="IRunTranscriptStore.ListAsync"/>.</summary>
+public sealed record TranscriptQuery
+{
+    public string? AgentId { get; init; }
+    public DateTime? From { get; init; }
+    public DateTime? To { get; init; }
+
+    /// <summary>Full text over the whole transcript.</summary>
+    public string? Search { get; init; }
+
+    public int Limit { get; init; } = 50;
+    public int Offset { get; init; }
+}
diff --git a/src/ClawdDotNet.Core/Transcripts/RunTranscriptRecorder.cs b/src/ClawdDotNet.Core/Transcripts/RunTranscriptRecorder.cs
new file mode 100644
index 0000000..aee898f
--- /dev/null
+++ b/src/ClawdDotNet.Core/Transcripts/RunTranscriptRecorder.cs
@@ -0,0 +1,212 @@
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.RegularExpressions;
+using ClawdDotNet.Core.Api.Models;
+
+namespace ClawdDotNet.Core.Transcripts;
+
+/// <summary>
+/// Collects the transcript of one run while it happens (#660). The engine calls it at the
+/// few points where something enters or leaves the conversation; nothing here talks to
+/// the model or the database.
+///
+/// <para>Recording is bounded: tool results are clipped to <see cref="MaxToolResultChars"/>,
+/// any single text to <see cref="MaxTextChars"/>, and the whole transcript to
+/// <see cref="MaxTotalChars"/>. Beyond that only the entry heads are kept (who called what,
+/// how many tokens), which is what an analysis of a runaway run needs anyway.</para>
+///
+/// <para>A disabled recorder (<see cref="Disabled"/>) accepts every call and keeps
+/// nothing, so the engine never has to branch.</para>
+/// </summary>
+public sealed class RunTranscriptRecorder
+{
+    public const int MaxToolResultChars = 4_000;
+    public const int MaxTextChars = 32_000;
+    public const int MaxTotalChars = 256_000;
+
+    private readonly Lock _lock = new();
+    private readonly List<TranscriptEntry> _entries = [];
+    private readonly TimeProvider _clock;
+    private int _size;
+    private bool _truncated;
+
+    public static RunTranscriptRecorder Disabled { get; } = new(enabled: false);
+
+    public bool Enabled { get; }
+    public string? SystemPrompt { get; private set; }
+    public DateTime StartedAt { get; }
+
+    public RunTranscriptRecorder(bool enabled = true, TimeProvider? clock = null)
+    {
+        Enabled = enabled;
+        _clock = clock ?? TimeProvider.System;
+        StartedAt = _clock.GetUtcNow().UtcDateTime;
+    }
+
+    // ─── Engine hooks ───
+
+    public void Begin(string? systemPrompt, string userMessage)
+    {
+        if (!Enabled) return;
+        SystemPrompt = string.IsNullOrWhiteSpace(systemPrompt) ? null : SecretScrubber.Scrub(systemPrompt);
+        Add(TranscriptEntryKind.User, userMessage, MaxTextChars);
+    }
+
+    /// <summary>A message the engine sent on its own (follow-up after an empty answer etc.).</summary>
+    public void EngineNote(string text)
+    {
+        if (!Enabled) return;
+        Add(TranscriptEntryKind.EngineNote, text, MaxTextChars);
+    }
+
+    public void Event(string text)
+    {
+        if (!Enabled) return;
+        Add(TranscriptEntryKind.Event, text, MaxTextChars);
+    }
+
+    /// <summary>One model response with the usage of exactly this request.</summary>
+    public void ModelStep(ChatMessage response, Usage? usage, string? finishReason)
+    {
+        if (!Enabled) return;
+
+        var calls = response.ToolCalls?
+            .Select(c => new TranscriptToolCall(
+                c.Id, c.Function.Name, Clip(SecretScrubber.Scrub(c.Function.Arguments ?? ""), MaxTextChars, out _)))
+            .ToList();
+
+        var (text, clipped) = Prepare(response.Content, MaxTextChars);
+
+        lock (_lock)
+        {
+            var groesse = (text?.Length ?? 0) + (calls?.Sum(c => c.Arguments.Length + c.Name.Length) ?? 0);
+            var ueber = _size + groesse > MaxTotalChars;
+            if (ueber) _truncated = true;
+
+            _entries.Add(new TranscriptEntry
+            {
+                Kind = TranscriptEntryKind.Assistant,
+                At = _clock.GetUtcNow().UtcDateTime,
+                Text = ueber ? null : text,
+                ToolCalls = ueber ? calls?.Select(c => c with { Arguments = "" }).ToList() : calls,
+                PromptTokens = usage?.PromptTokens,
+                CompletionTokens = usage?.CompletionTokens,
+                CachedTokens = usage?.CachedTokens,
+                CostUsd = usage?.Cost,
+                FinishReason = finishReason,
+                Clipped = clipped || ueber
+            });
+            if (!ueber) _size += groesse;
+        }
+    }
+
+    public void ToolResults(IReadOnlyList<ToolCall> calls, IReadOnlyList<string?> results)
+    {
+        if (!Enabled) return;
+        for (var i = 0; i < calls.Count; i++)
+        {
+            Add(TranscriptEntryKind.ToolResult, results.ElementAtOrDefault(i) ?? "(no result)", MaxToolResultChars,
+                calls[i].Id, calls[i].Function.Name);
+        }
+    }
+
+    // ─── Result ───
+
+    public RunTranscript Build(string runId, string agentId, string model, string source, string? taskId, string status)
+    {
+        lock (_lock)
+        {
+            return new RunTranscript
+            {
+                RunId = runId,
+                AgentId = agentId,
+                Model = model,
+                Source = source,
+                TaskId = taskId,
+                StartedAt = StartedAt,
+                CompletedAt = _clock.GetUtcNow().UtcDateTime,
+                Status = status,
+                SystemPromptHash = SystemPrompt is null ? null : Hash(SystemPrompt),
+                Entries = _entries.ToList(),
+                SizeChars = _size,
+                Truncated = _truncated
+            };
+        }
+    }
+
+    public static string Hash(string text)
+        => Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(text)))[..32].ToLowerInvariant();
+
+    // ─── Helpers ───
+
+    private void Add(string kind, string? text, int max, string? toolCallId = null, string? toolName = null)
+    {
+        var (prepared, clipped) = Prepare(text, max);
+        lock (_lock)
+        {
+            var ueber = _size + (prepared?.Length ?? 0) > MaxTotalChars;
+            if (ueber) _truncated = true;
+            _entries.Add(new TranscriptEntry
+            {
+                Kind = kind,
+                At = _clock.GetUtcNow().UtcDateTime,
+                Text = ueber ? null : prepared,
+                ToolCallId = toolCallId,
+                ToolName = toolName,
+                Clipped = clipped || ueber
+            });
+            if (!ueber) _size += prepared?.Length ?? 0;
+        }
+    }
+
+    private static (string? Text, bool Clipped) Prepare(string? text, int max)
+    {
+        if (string.IsNullOrEmpty(text)) return (text, false);
+        var clipped = Clip(SecretScrubber.Scrub(text), max, out var wasClipped);
+        return (clipped, wasClipped);
+    }
+
+    /// <summary>Keeps start and end — the end of a tool result is often the interesting part.</summary>
+    internal static string Clip(string text, int max, out bool clipped)
+    {
+        clipped = text.Length > max;
+        if (!clipped) return text;
+
+        var head = max * 3 / 4;
+        var tail = max - head;
+        return text[..head] + $"\n[… {text.Length - max} characters omitted …]\n" + text[^tail..];
+    }
+}
+
+/// <summary>
+/// Removes the kinds of secrets that can end up in prompts or tool results before a
+/// transcript is stored. Deliberately conservative: it targets recognisable secret
+/// formats, not arbitrary text.
+/// </summary>
+public static partial class SecretScrubber
+{
+    public const string Mask = "«redacted»";
+
+    public static string Scrub(string text)
+    {
+        if (string.IsNullOrEmpty(text)) return text;
+
+        text = ApiKey().Replace(text, Mask);
+        text = Bearer().Replace(text, "Bearer " + Mask);
+        text = PasswordAssignment().Replace(text, m => m.Groups["key"].Value + m.Groups["sep"].Value + Mask);
+        text = LicenseKey().Replace(text, Mask);
+        return text;
+    }
+
+    [GeneratedRegex(@"\b(?:sk-or-v1-|sk-or-|sk-ant-|sk-proj-|sk-|ghp_|gho_|github_pat_|xox[baprs]-)[A-Za-z0-9_\-]{16,}")]
+    private static partial Regex ApiKey();
+
+    [GeneratedRegex(@"Bearer\s+[A-Za-z0-9._~+/\-]{16,}=*", RegexOptions.IgnoreCase)]
+    private static partial Regex Bearer();
+
+    [GeneratedRegex(@"(?<key>\b(?:password|passwort|pwd|secret|api[_-]?key|token)\b)(?<sep>\s*[=:]\s*""?)[^;\s""',}]+", RegexOptions.IgnoreCase)]
+    private static partial Regex PasswordAssignment();
+
+    [GeneratedRegex(@"\b[A-Z0-9]{5}(?:-[A-Z0-9]{5}){4}\b")]
+    private static partial Regex LicenseKey();
+}
diff --git a/src/ClawdDotNet.Core/Transcripts/SqliteRunTranscriptStore.cs b/src/ClawdDotNet.Core/Transcripts/SqliteRunTranscriptStore.cs
new file mode 100644
index 0000000..1460c65
--- /dev/null
+++ b/src/ClawdDotNet.Core/Transcripts/SqliteRunTranscriptStore.cs
@@ -0,0 +1,211 @@
+using System.Globalization;
+using System.Text.Json;
+using ClawdDotNet.Core.Storage;
+using Microsoft.Data.Sqlite;
+
+namespace ClawdDotNet.Core.Transcripts;
+
+public interface IRunTranscriptStore
+{
+    Task SaveAsync(RunTranscript transcript, string? systemPrompt, CancellationToken ct);
+    Task<RunTranscript?> GetAsync(string runId, CancellationToken ct);
+    Task<string?> GetSystemPromptAsync(string hash, CancellationToken ct);
+    Task<(IReadOnlyList<RunTranscriptSummary> Items, int Total)> ListAsync(TranscriptQuery query, CancellationToken ct);
+
+    /// <summary>
+    /// Deletes what is older than each agent's retention allows. <paramref name="retentionFor"/>
+    /// returns the resolved retention in days for an agent id (0 = delete all, -1 = keep).
+    /// </summary>
+    Task<int> PurgeAsync(Func<string, int> retentionFor, DateTime now, CancellationToken ct);
+}
+
+/// <summary>
+/// Run transcripts in the instance database (#660). Entries are one JSON column per run:
+/// a transcript is always read and written as a whole, and the full-text search over
+/// it is a plain LIKE — enough for the volumes of a single instance.
+/// </summary>
+public sealed class SqliteRunTranscriptStore(SqliteStorage storage) : IRunTranscriptStore
+{
+    private static readonly JsonSerializerOptions Json = new(JsonSerializerDefaults.Web)
+    {
+        DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull,
+        // Unescaped, so the LIKE search finds "Grüße" as typed. Never rendered as HTML.
+        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping
+    };
+
+    private const string SummaryColumns =
+        "RunId, AgentId, Model, Source, TaskId, StartedAt, CompletedAt, Status, Prompt, Response, SizeChars, Truncated";
+
+    public Task SaveAsync(RunTranscript t, string? systemPrompt, CancellationToken ct)
+        => storage.WriteAsync(async conn =>
+        {
+            if (t.SystemPromptHash is not null && systemPrompt is not null)
+            {
+                using var sp = conn.CreateCommand();
+                sp.CommandText = """
+                    INSERT OR IGNORE INTO SystemPrompts (Hash, Text, FirstSeenAt) VALUES (@hash, @text, @at)
+                    """;
+                sp.Parameters.AddWithValue("@hash", t.SystemPromptHash);
+                sp.Parameters.AddWithValue("@text", systemPrompt);
+                sp.Parameters.AddWithValue("@at", Format(t.StartedAt));
+                await sp.ExecuteNonQueryAsync(ct);
+            }
+
+            using var cmd = conn.CreateCommand();
+            cmd.CommandText = """
+                INSERT OR REPLACE INTO RunTranscripts
+                    (RunId, AgentId, Model, Source, TaskId, StartedAt, CompletedAt, Status,
+                     SystemPromptHash, Prompt, Response, EntriesJson, SizeChars, Truncated)
+                VALUES
+                    (@runId, @agent, @model, @source, @task, @started, @completed, @status,
+                     @hash, @prompt, @response, @entries, @size, @truncated)
+                """;
+            cmd.Parameters.AddWithValue("@runId", t.RunId);
+            cmd.Parameters.AddWithValue("@agent", t.AgentId);
+            cmd.Parameters.AddWithValue("@model", t.Model);
+            cmd.Parameters.AddWithValue("@source", t.Source);
+            cmd.Parameters.AddWithValue("@task", (object?)t.TaskId ?? DBNull.Value);
+            cmd.Parameters.AddWithValue("@started", Format(t.StartedAt));
+            cmd.Parameters.AddWithValue("@completed", t.CompletedAt is { } c ? Format(c) : DBNull.Value);
+            cmd.Parameters.AddWithValue("@status", t.Status);
+            cmd.Parameters.AddWithValue("@hash", (object?)t.SystemPromptHash ?? DBNull.Value);
+            cmd.Parameters.AddWithValue("@prompt", Snippet(t.Entries.FirstOrDefault(e => e.Kind == TranscriptEntryKind.User)?.Text));
+            cmd.Parameters.AddWithValue("@response", Snippet(t.Entries.LastOrDefault(e => e.Kind == TranscriptEntryKind.Assistant && !string.IsNullOrWhiteSpace(e.Text))?.Text));
+            cmd.Parameters.AddWithValue("@entries", JsonSerializer.Serialize(t.Entries, Json));
+            cmd.Parameters.AddWithValue("@size", t.SizeChars);
+            cmd.Parameters.AddWithValue("@truncated", t.Truncated ? 1 : 0);
+            await cmd.ExecuteNonQueryAsync(ct);
+            return true;
+        }, ct);
+
+    public async Task<RunTranscript?> GetAsync(string runId, CancellationToken ct)
+    {
+        await using var conn = await storage.OpenConnectionAsync(ct);
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            SELECT RunId, AgentId, Model, Source, TaskId, StartedAt, CompletedAt, Status,
+                   SystemPromptHash, EntriesJson, SizeChars, Truncated
+              FROM RunTranscripts WHERE RunId = @runId
+            """;
+        cmd.Parameters.AddWithValue("@runId", runId);
+        await using var r = await cmd.ExecuteReaderAsync(ct);
+        if (!await r.ReadAsync(ct)) return null;
+
+        return new RunTranscript
+        {
+            RunId = r.GetString(0),
+            AgentId = r.GetString(1),
+            Model = r.GetString(2),
+            Source = r.GetString(3),
+            TaskId = r.IsDBNull(4) ? null : r.GetString(4),
+            StartedAt = Parse(r.GetString(5)),
+            CompletedAt = r.IsDBNull(6) ? null : Parse(r.GetString(6)),
+            Status = r.GetString(7),
+            SystemPromptHash = r.IsDBNull(8) ? null : r.GetString(8),
+            Entries = JsonSerializer.Deserialize<List<TranscriptEntry>>(r.GetString(9), Json) ?? [],
+            SizeChars = r.GetInt32(10),
+            Truncated = r.GetInt32(11) != 0
+        };
+    }
+
+    public async Task<string?> GetSystemPromptAsync(string hash, CancellationToken ct)
+    {
+        await using var conn = await storage.OpenConnectionAsync(ct);
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = "SELECT Text FROM SystemPrompts WHERE Hash = @hash";
+        cmd.Parameters.AddWithValue("@hash", hash);
+        return await cmd.ExecuteScalarAsync(ct) as string;
+    }
+
+    public async Task<(IReadOnlyList<RunTranscriptSummary> Items, int Total)> ListAsync(TranscriptQuery q, CancellationToken ct)
+    {
+        await using var conn = await storage.OpenConnectionAsync(ct);
+
+        var where = new List<string>();
+        void Bind(SqliteCommand c)
+        {
+            if (!string.IsNullOrWhiteSpace(q.AgentId)) c.Parameters.AddWithValue("@agent", q.AgentId);
+            if (q.From is { } f) c.Parameters.AddWithValue("@from", Format(f));
+            if (q.To is { } t) c.Parameters.AddWithValue("@to", Format(t));
+            if (!string.IsNullOrWhiteSpace(q.Search)) c.Parameters.AddWithValue("@q", "%" + Escape(q.Search.Trim()) + "%");
+        }
+        if (!string.IsNullOrWhiteSpace(q.AgentId)) where.Add("AgentId = @agent");
+        if (q.From is not null) where.Add("StartedAt >= @from");
+        if (q.To is not null) where.Add("StartedAt < @to");
+        if (!string.IsNullOrWhiteSpace(q.Search)) where.Add("EntriesJson LIKE @q ESCAPE '\\'");
+        var filter = where.Count == 0 ? "" : " WHERE " + string.Join(" AND ", where);
+
+        using var count = conn.CreateCommand();
+        count.CommandText = "SELECT COUNT(*) FROM RunTranscripts" + filter;
+        Bind(count);
+        var total = Convert.ToInt32(await count.ExecuteScalarAsync(ct));
+
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = $"SELECT {SummaryColumns} FROM RunTranscripts{filter} ORDER BY StartedAt DESC LIMIT @limit OFFSET @offset";
+        Bind(cmd);
+        cmd.Parameters.AddWithValue("@limit", Math.Clamp(q.Limit, 1, 500));
+        cmd.Parameters.AddWithValue("@offset", Math.Max(0, q.Offset));
+
+        var items = new List<RunTranscriptSummary>();
+        await using var r = await cmd.ExecuteReaderAsync(ct);
+        while (await r.ReadAsync(ct))
+        {
+            items.Add(new RunTranscriptSummary(
+                r.GetString(0), r.GetString(1), r.GetString(2), r.GetString(3),
+                r.IsDBNull(4) ? null : r.GetString(4),
+                Parse(r.GetString(5)),
+                r.IsDBNull(6) ? null : Parse(r.GetString(6)),
+                r.GetString(7), r.GetString(8), r.GetString(9), r.GetInt32(10), r.GetInt32(11) != 0));
+        }
+        return (items, total);
+    }
+
+    public Task<int> PurgeAsync(Func<string, int> retentionFor, DateTime now, CancellationToken ct)
+        => storage.WriteAsync(async conn =>
+        {
+            var agents = new List<string>();
+            using (var list = conn.CreateCommand())
+            {
+                list.CommandText = "SELECT DISTINCT AgentId FROM RunTranscripts";
+                await using var r = await list.ExecuteReaderAsync(ct);
+                while (await r.ReadAsync(ct)) agents.Add(r.GetString(0));
+            }
+
+            var deleted = 0;
+            foreach (var agent in agents)
+            {
+                var days = PromptHistorySettings.Normalize(retentionFor(agent));
+                if (days == PromptHistorySettings.Forever) continue;
+
+                using var del = conn.CreateCommand();
+                del.CommandText = "DELETE FROM RunTranscripts WHERE AgentId = @agent AND StartedAt < @cutoff";
+                del.Parameters.AddWithValue("@agent", agent);
+                // Never (0): everything goes, including what was recorded before the switch.
+                del.Parameters.AddWithValue("@cutoff", Format(days == PromptHistorySettings.Never ? DateTime.MaxValue : now.AddDays(-days)));
+                deleted += await del.ExecuteNonQueryAsync(ct);
+            }
+
+            using var orphans = conn.CreateCommand();
+            orphans.CommandText = """
+                DELETE FROM SystemPrompts
+                 WHERE Hash NOT IN (SELECT SystemPromptHash FROM RunTranscripts WHERE SystemPromptHash IS NOT NULL)
+                """;
+            await orphans.ExecuteNonQueryAsync(ct);
+            return deleted;
+        }, ct);
+
+    private static string Snippet(string? text)
+    {
+        if (string.IsNullOrWhiteSpace(text)) return "";
+        var t = text.Trim();
+        return t.Length <= 300 ? t : t[..300] + "…";
+    }
+
+    private static string Escape(string s) => s.Replace("\\", "\\\\").Replace("%", "\\%").Replace("_", "\\_");
+
+    private static string Format(DateTime value)
+        => (value == DateTime.MaxValue ? value : value.ToUniversalTime()).ToString("O", CultureInfo.InvariantCulture);
+
+    private static DateTime Parse(string value)
+        => DateTime.Parse(value, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind).ToUniversalTime();
+}
diff --git a/src/ClawdDotNet.Core/Transcripts/TranscriptJanitor.cs b/src/ClawdDotNet.Core/Transcripts/TranscriptJanitor.cs
new file mode 100644
index 0000000..1269004
--- /dev/null
+++ b/src/ClawdDotNet.Core/Transcripts/TranscriptJanitor.cs
@@ -0,0 +1,58 @@
+using Microsoft.Extensions.Logging;
+
+namespace ClawdDotNet.Core.Transcripts;
+
+/// <summary>
+/// Enforces the prompt history retention (#660): once at start and then every hour,
+/// transcripts older than their agent's retention are deleted. An agent switched to
+/// "never" loses everything recorded before the switch — that is the point of the switch.
+/// </summary>
+public sealed class TranscriptJanitor(
+    IRunTranscriptStore store,
+    Func<string, int> retentionFor,
+    ILogger logger,
+    TimeProvider? clock = null,
+    TimeSpan? interval = null) : IAsyncDisposable
+{
+    private readonly TimeProvider _clock = clock ?? TimeProvider.System;
+    private readonly CancellationTokenSource _cts = new();
+    private Task? _loop;
+
+    public void Start() => _loop ??= RunAsync(_cts.Token);
+
+    public async Task<int> PurgeOnceAsync(CancellationToken ct)
+    {
+        var deleted = await store.PurgeAsync(retentionFor, _clock.GetUtcNow().UtcDateTime, ct);
+        if (deleted > 0)
+            logger.LogInformation("Prompt history: {Count} transcript(s) past their retention deleted", deleted);
+        return deleted;
+    }
+
+    private async Task RunAsync(CancellationToken ct)
+    {
+        using var timer = new PeriodicTimer(interval ?? TimeSpan.FromHours(1), _clock);
+        do
+        {
+            try
+            {
+                await PurgeOnceAsync(ct);
+            }
+            catch (Exception ex) when (ex is not OperationCanceledException)
+            {
+                logger.LogWarning(ex, "Prompt history cleanup failed");
+            }
+        }
+        while (await timer.WaitForNextTickAsync(ct));
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        await _cts.CancelAsync();
+        if (_loop is not null)
+        {
+            try { await _loop; }
+            catch (OperationCanceledException) { }
+        }
+        _cts.Dispose();
+    }
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/app.css b/src/ClawdDotNet.Manager.Web/wwwroot/app.css
index b87d265..c781a6d 100644
--- a/src/ClawdDotNet.Manager.Web/wwwroot/app.css
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/app.css
@@ -1415,3 +1415,309 @@ button.klein {
   margin-top: 10px;
   font-size: 14px;
 }
+
+/* ─── Token usage analysis and prompt history (#660) ─── */
+
+.nav-unterlink {
+  padding-left: 42px;
+  font-size: 13px;
+}
+
+.seitenleiste.kollabiert .nav-unterlink {
+  display: none;
+}
+
+.filter-leiste {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: flex-end;
+  gap: 10px 14px;
+  margin: 12px 0 16px;
+}
+
+.filter-feld {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  font-size: 12px;
+  color: var(--gedaempft);
+}
+
+.filter-feld select,
+.filter-feld input {
+  min-width: 140px;
+}
+
+.filter-suche input {
+  min-width: 220px;
+}
+
+.filter-eigen {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.filter-aktionen {
+  display: flex;
+  gap: 6px;
+}
+
+.kennzahlen-raster {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+  gap: 12px;
+}
+
+.kennzahl {
+  border: 1px solid var(--divider);
+  padding: 10px 12px;
+}
+
+.kennzahl-wert {
+  font-size: 20px;
+  font-weight: 600;
+}
+
+.kennzahl-titel {
+  font-size: 12px;
+  color: var(--gedaempft);
+}
+
+.tabelle-scroll,
+.diagramm-scroll {
+  overflow-x: auto;
+}
+
+.daten-tabelle td.zahl,
+.daten-tabelle th.zahl {
+  text-align: right;
+  font-variant-numeric: tabular-nums;
+}
+
+.sortier-knopf {
+  background: none;
+  border: 0;
+  padding: 0;
+  font: inherit;
+  color: inherit;
+  text-transform: inherit;
+  letter-spacing: inherit;
+  cursor: pointer;
+}
+
+.klickbar {
+  cursor: pointer;
+}
+
+.klickbar:focus-visible {
+  outline: 2px solid var(--accent);
+}
+
+.blaettern {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+  margin-top: 12px;
+}
+
+.zurueck-link {
+  display: inline-block;
+  margin-bottom: 8px;
+}
+
+.diagramm-steuerung {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px 24px;
+  margin-bottom: 12px;
+}
+
+.zeitverlauf .raster {
+  stroke: var(--divider);
+  stroke-width: 1;
+}
+
+.zeitverlauf .achse {
+  fill: var(--gedaempft);
+  font-size: 11px;
+}
+
+.zeitverlauf .balken {
+  cursor: pointer;
+}
+
+.zeitverlauf .balken:hover,
+.zeitverlauf .balken:focus {
+  opacity: 0.8;
+  outline: none;
+}
+
+.zeitverlauf .ereignis line {
+  stroke-width: 1.5;
+  stroke-dasharray: 4 3;
+}
+
+.zeitverlauf .ereignis-budget line,
+.zeitverlauf .ereignis-budget path {
+  stroke: var(--gefahr);
+  fill: var(--gefahr);
+}
+
+.zeitverlauf .ereignis-modell line,
+.zeitverlauf .ereignis-modell path {
+  stroke: var(--accent);
+  fill: var(--accent);
+}
+
+.legende {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px 16px;
+  margin-top: 10px;
+  font-size: 13px;
+}
+
+.legende-eintrag {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.legende-farbe {
+  width: 12px;
+  height: 12px;
+  display: inline-block;
+}
+
+.legende-marke {
+  width: 0;
+  height: 12px;
+  display: inline-block;
+  border-left: 2px dashed;
+}
+
+.legende-marke.ereignis-budget {
+  border-color: var(--gefahr);
+}
+
+.legende-marke.ereignis-modell {
+  border-color: var(--accent);
+}
+
+.transkript-system {
+  margin-bottom: 12px;
+}
+
+.transkript-eintrag {
+  border-left: 3px solid var(--divider);
+  padding: 6px 0 6px 12px;
+  margin: 10px 0;
+}
+
+.transkript-eintrag.art-user { border-left-color: var(--accent); }
+.transkript-eintrag.art-assistant { border-left-color: var(--erfolg); }
+.transkript-eintrag.art-tool_result { border-left-color: var(--warnung); }
+.transkript-eintrag.art-engine,
+.transkript-eintrag.art-event { border-left-color: var(--gedaempft); }
+
+.transkript-kopf {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 4px;
+}
+
+.transkript-text {
+  white-space: pre-wrap;
+  word-break: break-word;
+  max-height: 420px;
+  overflow-y: auto;
+  margin: 4px 0;
+}
+
+.transkript-aufruf {
+  margin-top: 6px;
+}
+
+.schlichte-liste {
+  list-style: none;
+  padding: 0;
+  margin: 0;
+}
+
+.schlichte-liste li {
+  padding: 4px 0;
+}
+
+.verlauf-eintrag {
+  border: 1px solid var(--divider);
+  padding: 10px 12px;
+  margin-bottom: 10px;
+}
+
+.verlauf-eintrag:hover {
+  background: var(--surface-hover);
+}
+
+.verlauf-kopf {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 10px;
+  margin-bottom: 6px;
+}
+
+.verlauf-zeile {
+  display: flex;
+  gap: 10px;
+  font-size: 14px;
+  margin: 2px 0;
+}
+
+.verlauf-marke {
+  flex: 0 0 80px;
+  color: var(--gedaempft);
+  font-size: 12px;
+  text-transform: uppercase;
+}
+
+.verlauf-text {
+  flex: 1;
+  overflow: hidden;
+  display: -webkit-box;
+  -webkit-line-clamp: 2;
+  -webkit-box-orient: vertical;
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+.aufbewahrung input[type="number"] {
+  width: 80px;
+}
+
+@media (max-width: 768px) {
+  .filter-feld select,
+  .filter-feld input,
+  .filter-suche input {
+    min-width: 0;
+    width: 100%;
+  }
+
+  .filter-feld {
+    flex: 1 1 140px;
+  }
+
+  .verlauf-zeile {
+    flex-direction: column;
+    gap: 2px;
+  }
+}
+
+span.klein,
+div.klein,
+td.klein {
+  font-size: 12px;
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/app.js b/src/ClawdDotNet.Manager.Web/wwwroot/app.js
index 556fa99..6595cf7 100644
--- a/src/ClawdDotNet.Manager.Web/wwwroot/app.js
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/app.js
@@ -30,6 +30,11 @@ import { rendereInstanzen, stoppePolling as stoppeInstanzenPolling } from "./vie
 import { rendereEinstellungen } from "./views/settings.js";
 import { rendereSicherung } from "./views/backup.js";
 import { rendereAgentenChats, trenneAgentenChatsStream } from "./views/agent-chats.js";
+import { loadLanguage, translateDocument } from "./modules/i18n.js";
+import { renderUsageRuns } from "./views/usage-runs.js";
+import { renderUsageTimeline } from "./views/usage-timeline.js";
+import { renderRunDetail } from "./views/run-detail.js";
+import { renderPromptHistory } from "./views/prompt-history.js";
 
 // ─── 1. Routen registrieren ───
 
@@ -48,6 +53,12 @@ registriereRoute("/aufgaben", () => { verlasseAnsicht(); return rendereAufgaben(
 registriereRoute("/dienste", () => { verlasseAnsicht(); return rendereDienste(); });
 registriereRoute("/staging", () => { verlasseAnsicht(); return rendereStaging(); });
 registriereRoute("/verbrauch", () => { verlasseAnsicht(); return rendereVerbrauch(); });
+// #660: token usage sub-views and the prompt history
+registriereRoute("/verbrauch/runs", () => { verlasseAnsicht(); return renderUsageRuns(); });
+registriereRoute("/verbrauch/runs/:runId", (p) => { verlasseAnsicht(); return renderRunDetail(p.runId, "/verbrauch/runs"); });
+registriereRoute("/verbrauch/timeline", () => { verlasseAnsicht(); return renderUsageTimeline(); });
+registriereRoute("/prompt-history", () => { verlasseAnsicht(); return renderPromptHistory(); });
+registriereRoute("/prompt-history/:runId", (p) => { verlasseAnsicht(); return renderRunDetail(p.runId, "/prompt-history"); });
 registriereRoute("/agenten-chats", () => { verlasseAnsicht(); return rendereAgentenChats(); });
 registriereRoute("/protokoll", () => { verlasseAnsicht(); return rendereProtokoll(); });
 registriereRoute("/sicherung", () => { verlasseAnsicht(); return rendereSicherung(); });
@@ -352,6 +363,10 @@ async function starteHauptAnwendung(instanzen) {
     }
   });
 
+  // #661: language packs before the first render
+  await loadLanguage();
+  translateDocument();
+
   // Router initialisieren
   initialisiereRouter();
 }
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/i18n/de.json b/src/ClawdDotNet.Manager.Web/wwwroot/i18n/de.json
new file mode 100644
index 0000000..2d711ff
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/i18n/de.json
@@ -0,0 +1,141 @@
+{
+  "nav.usage.runs": "Läufe",
+  "nav.usage.timeline": "Zeitverlauf",
+  "nav.promptHistory": "Prompt-Verlauf",
+
+  "common.loading": "Lade…",
+  "common.previous": "Zurück",
+  "common.next": "Weiter",
+
+  "filter.range": "Zeitraum",
+  "filter.range.24h": "Letzte 24 Stunden",
+  "filter.range.7d": "Letzte 7 Tage",
+  "filter.range.30d": "Letzte 30 Tage",
+  "filter.range.90d": "Letzte 90 Tage",
+  "filter.range.custom": "Eigener…",
+  "filter.from": "Von",
+  "filter.to": "Bis",
+  "filter.agent": "Agent",
+  "filter.model": "Modell",
+  "filter.event": "Ereignis",
+  "filter.status": "Status",
+  "filter.all": "Alle",
+  "filter.minCost": "Kosten ab ($)",
+  "filter.search": "Suche",
+  "filter.search.placeholder": "Aufgabe, Ergebnis, Lauf-ID…",
+  "filter.apply": "Anwenden",
+  "filter.reset": "Zurücksetzen",
+
+  "source.task": "Aufgabe",
+  "source.direct": "Direkter Lauf",
+  "source.approval": "Freigabe",
+  "source.webview": "Chat (Fenster)",
+  "source.webui": "Chat (Web)",
+  "source.telegram": "Telegram",
+  "source.agentcomm": "Delegation",
+  "source.job": "Job",
+  "source.unknown": "Unbekannt",
+
+  "runs.title": "Tokennutzung › Läufe",
+  "runs.unavailable": "Keine Verbrauchsdaten",
+  "runs.totals": "Summen für diesen Filter",
+  "runs.total.runs": "Läufe",
+  "runs.total.prompt": "Prompt-Tokens",
+  "runs.total.completion": "Antwort-Tokens",
+  "runs.total.cached": "Aus dem Cache",
+  "runs.total.cost": "Kosten",
+  "runs.total.notRun": "Abgewiesen (Budget, Herunterfahren)",
+  "runs.unknownCost": "{n} Lauf/Läufe ohne bekannten Preis sind mit 0 $ gezählt.",
+  "runs.empty.title": "Keine Läufe",
+  "runs.empty.text": "Kein Lauf passt zu diesem Filter.",
+  "runs.list": "Läufe",
+  "runs.page": "{from}–{to} von {total}",
+  "runs.col.time": "Zeit",
+  "runs.col.agent": "Agent",
+  "runs.col.model": "Modell",
+  "runs.col.event": "Ereignis",
+  "runs.col.status": "Status",
+  "runs.col.steps": "Schritte",
+  "runs.col.prompt": "Prompt",
+  "runs.col.completion": "Antwort",
+  "runs.col.cost": "Kosten",
+  "runs.col.duration": "Dauer",
+
+  "detail.back": "← Zurück",
+  "detail.title": "Lauf",
+  "detail.notFound": "Lauf nicht gefunden",
+  "detail.runId": "Lauf-ID",
+  "detail.tokens": "Tokens",
+  "detail.tokensValue": "{prompt} Prompt · {completion} Antwort · {cached} aus dem Cache",
+  "detail.result": "Ergebnis",
+  "detail.receipt": "Beleg",
+  "detail.transcript": "Prompt und Antwort",
+  "detail.transcript.disabled": "Für diesen Agenten ist der Prompt-Verlauf abgeschaltet (Aufbewahrung: nie).",
+  "detail.transcript.unavailable": "Diese Instanz zeichnet keinen Prompt-Verlauf auf.",
+  "detail.transcript.missing": "Kein Transkript zu diesem Lauf – er lief vor Beginn der Aufzeichnung oder ist über seine Aufbewahrungsfrist hinaus.",
+  "detail.transcript.truncated": "Dieser Lauf hat die Größengrenze des Prompt-Verlaufs überschritten; spätere Einträge sind gekürzt.",
+  "detail.transcript.size": "{n} Einträge, {chars} Zeichen",
+  "detail.systemPrompt": "Systemprompt ({n} Zeichen)",
+  "detail.entry.user": "Auftrag / Nachricht",
+  "detail.entry.engine": "Nachfrage der Engine",
+  "detail.entry.event": "Ereignis",
+  "detail.entry.assistant": "Modellschritt {n}",
+  "detail.entry.usage": "{prompt} rein · {completion} raus",
+  "detail.entry.tool_result": "Ergebnis: {tool}",
+  "detail.entry.call": "Ruft {tool} auf",
+  "detail.entry.clipped": "gekürzt",
+  "detail.tool": "Werkzeug",
+  "detail.arguments": "Argumente",
+  "detail.toolCalls": "Werkzeugaufrufe",
+  "detail.toolCalls.hint": "Aus dem Audit-Log – auch ohne Transkript vorhanden.",
+  "detail.approvals": "Zur Freigabe vorgelegt",
+
+  "timeline.title": "Tokennutzung › Zeitverlauf",
+  "timeline.chart": "Zeitverlauf",
+  "timeline.metric": "Maß",
+  "timeline.metric.cost": "Kosten",
+  "timeline.metric.tokens": "Tokens",
+  "timeline.metric.runs": "Läufe",
+  "timeline.groupBy": "Nach",
+  "timeline.groupBy.agent": "Agent",
+  "timeline.groupBy.model": "Modell",
+  "timeline.groupBy.source": "Ereignis",
+  "timeline.bucket": "Je",
+  "timeline.bucket.hour": "Stunde",
+  "timeline.bucket.day": "Tag",
+  "timeline.tooltipRuns": "{n} Lauf/Läufe",
+  "timeline.event.budget_exceeded": "Budget erschöpft",
+  "timeline.event.model_changed": "Modell gewechselt",
+  "timeline.hint": "Ein Klick auf einen Balken zeigt dessen Läufe.",
+
+  "history.title": "Prompt-Verlauf",
+  "history.intro": "Prompt und Antwort jedes Laufs, durchsuchbar über das ganze Gespräch samt Werkzeugaufrufen und Ergebnissen.",
+  "history.unavailable": "Prompt-Verlauf nicht verfügbar",
+  "history.empty.title": "Nichts aufgezeichnet",
+  "history.empty.text": "Keine Transkripte in diesem Zeitraum. Die Aufzeichnung beginnt mit Version 0.1.12 und folgt der Aufbewahrung unten.",
+  "history.empty.search": "Kein Transkript enthält diesen Text.",
+  "history.list": "Transkripte ({n})",
+  "history.prompt": "Prompt",
+  "history.response": "Antwort",
+  "history.truncated": "Größengrenze erreicht ({chars} Zeichen gespeichert).",
+
+  "history.settings.title": "Aufbewahrung",
+  "history.settings.intro": "Wie lange Prompts und Antworten aufbewahrt werden. Die Vorgabe gilt für jeden Agenten ohne eigene Einstellung; „nie“ löscht auch, was vorher aufgezeichnet wurde.",
+  "history.settings.default": "Vorgabe für alle Agenten:",
+  "history.settings.agent": "Agent",
+  "history.settings.retention": "Aufbewahrung",
+  "history.settings.effective": "Gilt",
+  "history.settings.mode": "Aufbewahrung",
+  "history.settings.mode.inherit": "Vorgabe",
+  "history.settings.mode.never": "Nie aufzeichnen",
+  "history.settings.mode.days": "Tage",
+  "history.settings.mode.forever": "Unbegrenzt",
+  "history.settings.days": "Tage",
+  "history.settings.daysUnit": "Tage",
+  "history.settings.effective.never": "wird nicht aufgezeichnet",
+  "history.settings.effective.forever": "unbegrenzt",
+  "history.settings.effective.days": "{n} Tage",
+  "history.settings.save": "Aufbewahrung speichern",
+  "history.settings.saved": "Aufbewahrung gespeichert.",
+  "history.settings.failed": "Speichern fehlgeschlagen: {error}"
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/i18n/en.json b/src/ClawdDotNet.Manager.Web/wwwroot/i18n/en.json
new file mode 100644
index 0000000..4264f1b
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/i18n/en.json
@@ -0,0 +1,141 @@
+{
+  "nav.usage.runs": "Runs",
+  "nav.usage.timeline": "Timeline",
+  "nav.promptHistory": "Prompt History",
+
+  "common.loading": "Loading…",
+  "common.previous": "Previous",
+  "common.next": "Next",
+
+  "filter.range": "Period",
+  "filter.range.24h": "Last 24 hours",
+  "filter.range.7d": "Last 7 days",
+  "filter.range.30d": "Last 30 days",
+  "filter.range.90d": "Last 90 days",
+  "filter.range.custom": "Custom…",
+  "filter.from": "From",
+  "filter.to": "To",
+  "filter.agent": "Agent",
+  "filter.model": "Model",
+  "filter.event": "Event",
+  "filter.status": "Status",
+  "filter.all": "All",
+  "filter.minCost": "Cost from ($)",
+  "filter.search": "Search",
+  "filter.search.placeholder": "Task, result, run id…",
+  "filter.apply": "Apply",
+  "filter.reset": "Reset",
+
+  "source.task": "Task",
+  "source.direct": "Direct run",
+  "source.approval": "Approval",
+  "source.webview": "Chat (window)",
+  "source.webui": "Chat (web)",
+  "source.telegram": "Telegram",
+  "source.agentcomm": "Delegation",
+  "source.job": "Job",
+  "source.unknown": "Unknown",
+
+  "runs.title": "Token usage › Runs",
+  "runs.unavailable": "No usage data",
+  "runs.totals": "Totals for this filter",
+  "runs.total.runs": "Runs",
+  "runs.total.prompt": "Prompt tokens",
+  "runs.total.completion": "Completion tokens",
+  "runs.total.cached": "From cache",
+  "runs.total.cost": "Cost",
+  "runs.total.notRun": "Refused (budget, shutdown)",
+  "runs.unknownCost": "{n} run(s) without a known price are counted with 0 $.",
+  "runs.empty.title": "No runs",
+  "runs.empty.text": "No run matches this filter.",
+  "runs.list": "Runs",
+  "runs.page": "{from}–{to} of {total}",
+  "runs.col.time": "Time",
+  "runs.col.agent": "Agent",
+  "runs.col.model": "Model",
+  "runs.col.event": "Event",
+  "runs.col.status": "Status",
+  "runs.col.steps": "Steps",
+  "runs.col.prompt": "Prompt",
+  "runs.col.completion": "Response",
+  "runs.col.cost": "Cost",
+  "runs.col.duration": "Duration",
+
+  "detail.back": "← Back",
+  "detail.title": "Run",
+  "detail.notFound": "Run not found",
+  "detail.runId": "Run id",
+  "detail.tokens": "Tokens",
+  "detail.tokensValue": "{prompt} prompt · {completion} response · {cached} from cache",
+  "detail.result": "Result",
+  "detail.receipt": "Receipt",
+  "detail.transcript": "Prompt and response",
+  "detail.transcript.disabled": "Prompt history is switched off for this agent (retention: never).",
+  "detail.transcript.unavailable": "This instance does not record a prompt history.",
+  "detail.transcript.missing": "No transcript for this run - it ran before recording started or is past its retention.",
+  "detail.transcript.truncated": "This run exceeded the size limit of the prompt history; later entries are shortened.",
+  "detail.transcript.size": "{n} entries, {chars} characters",
+  "detail.systemPrompt": "System prompt ({n} characters)",
+  "detail.entry.user": "Task / message",
+  "detail.entry.engine": "Follow-up by the engine",
+  "detail.entry.event": "Event",
+  "detail.entry.assistant": "Model step {n}",
+  "detail.entry.usage": "{prompt} in · {completion} out",
+  "detail.entry.tool_result": "Result: {tool}",
+  "detail.entry.call": "Calls {tool}",
+  "detail.entry.clipped": "shortened",
+  "detail.tool": "Tool",
+  "detail.arguments": "Arguments",
+  "detail.toolCalls": "Tool calls",
+  "detail.toolCalls.hint": "From the audit log - available even without a transcript.",
+  "detail.approvals": "Proposed for approval",
+
+  "timeline.title": "Token usage › Timeline",
+  "timeline.chart": "Timeline",
+  "timeline.metric": "Measure",
+  "timeline.metric.cost": "Cost",
+  "timeline.metric.tokens": "Tokens",
+  "timeline.metric.runs": "Runs",
+  "timeline.groupBy": "By",
+  "timeline.groupBy.agent": "Agent",
+  "timeline.groupBy.model": "Model",
+  "timeline.groupBy.source": "Event",
+  "timeline.bucket": "Per",
+  "timeline.bucket.hour": "Hour",
+  "timeline.bucket.day": "Day",
+  "timeline.tooltipRuns": "{n} run(s)",
+  "timeline.event.budget_exceeded": "Budget exhausted",
+  "timeline.event.model_changed": "Model changed",
+  "timeline.hint": "Click a bar to see its runs.",
+
+  "history.title": "Prompt History",
+  "history.intro": "Prompt and response of every run, searchable over the whole conversation including tool calls and results.",
+  "history.unavailable": "Prompt history not available",
+  "history.empty.title": "Nothing recorded",
+  "history.empty.text": "No transcripts in this period. Recording starts with version 0.1.12 and follows the retention below.",
+  "history.empty.search": "No transcript contains this text.",
+  "history.list": "Transcripts ({n})",
+  "history.prompt": "Prompt",
+  "history.response": "Response",
+  "history.truncated": "Size limit reached ({chars} characters stored).",
+
+  "history.settings.title": "Retention",
+  "history.settings.intro": "How long prompts and responses are kept. The default applies to every agent without its own setting; \"never\" also deletes what was recorded before.",
+  "history.settings.default": "Default for all agents:",
+  "history.settings.agent": "Agent",
+  "history.settings.retention": "Retention",
+  "history.settings.effective": "Applies",
+  "history.settings.mode": "Retention",
+  "history.settings.mode.inherit": "Default",
+  "history.settings.mode.never": "Never record",
+  "history.settings.mode.days": "Days",
+  "history.settings.mode.forever": "Keep forever",
+  "history.settings.days": "Days",
+  "history.settings.daysUnit": "days",
+  "history.settings.effective.never": "not recorded",
+  "history.settings.effective.forever": "kept forever",
+  "history.settings.effective.days": "kept {n} days",
+  "history.settings.save": "Save retention",
+  "history.settings.saved": "Retention saved.",
+  "history.settings.failed": "Saving failed: {error}"
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/index.html b/src/ClawdDotNet.Manager.Web/wwwroot/index.html
index ce9a013..e9e52a8 100644
--- a/src/ClawdDotNet.Manager.Web/wwwroot/index.html
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/index.html
@@ -71,12 +71,24 @@
 
       <div class="nav-gruppe">
         <div class="nav-gruppe-titel">Analyse</div>
-        <a href="#/verbrauch" class="nav-link" title="Tokennutzung">
+        <a href="#/verbrauch" class="nav-link" title="Tokennutzung" data-exakt>
           <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
             <path d="M3 3v18h18 M7 15v4 M11 11v8 M15 7v12 M19 12v7"/>
           </svg>
           <span class="nav-label">Tokennutzung</span>
         </a>
+        <a href="#/verbrauch/runs" class="nav-link nav-unterlink" data-i18n-title="nav.usage.runs">
+          <span class="nav-label" data-i18n="nav.usage.runs">Runs</span>
+        </a>
+        <a href="#/verbrauch/timeline" class="nav-link nav-unterlink" data-i18n-title="nav.usage.timeline">
+          <span class="nav-label" data-i18n="nav.usage.timeline">Timeline</span>
+        </a>
+        <a href="#/prompt-history" class="nav-link" data-i18n-title="nav.promptHistory">
+          <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
+            <path d="M12 8v4l3 2 M3.05 11a9 9 0 1 1 .5 4 M3 20v-5h5"/>
+          </svg>
+          <span class="nav-label" data-i18n="nav.promptHistory">Prompt History</span>
+        </a>
         <a href="#/agenten-chats" class="nav-link" title="Agenten-Chats">
           <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
             <path d="M8 12h.01M12 12h.01M16 12h.01 M21 12c0 4.4-4 8-9 8-1.3 0-2.6-.2-3.7-.7L3 20l1-4.2C3.4 14.6 3 13.3 3 12c0-4.4 4-8 9-8s9 3.6 9 8Z"/>
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/modules/i18n.js b/src/ClawdDotNet.Manager.Web/wwwroot/modules/i18n.js
new file mode 100644
index 0000000..a703281
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/modules/i18n.js
@@ -0,0 +1,63 @@
+// ClawdDotNet — translations (#661)
+//
+// English is the main language: every key has its English text in i18n/en.json, and that
+// pack is always loaded as the fallback. Other languages live in their own packs next to
+// it (i18n/de.json, ...), separate from the code. A missing key falls back to English,
+// a key missing there too shows the key itself - visible, so it gets noticed.
+//
+// The language selection itself is part of #661; until then the choice is read from
+// localStorage ("clawd.language") and defaults to English.
+
+export const LANGUAGE_KEY = "clawd.language";
+export const DEFAULT_LANGUAGE = "en";
+
+let fallbackPack = {};
+let activePack = {};
+let activeLanguage = DEFAULT_LANGUAGE;
+
+async function loadPack(language) {
+  try {
+    const response = await fetch(`i18n/${encodeURIComponent(language)}.json`, { cache: "no-cache" });
+    return response.ok ? await response.json() : {};
+  } catch {
+    return {};
+  }
+}
+
+/** Loads English plus the selected language. Call once before the first render. */
+export async function loadLanguage() {
+  let wanted = DEFAULT_LANGUAGE;
+  try {
+    wanted = localStorage.getItem(LANGUAGE_KEY) || DEFAULT_LANGUAGE;
+  } catch {
+    // Storage blocked: stay with English.
+  }
+
+  fallbackPack = await loadPack(DEFAULT_LANGUAGE);
+  activePack = wanted === DEFAULT_LANGUAGE ? fallbackPack : await loadPack(wanted);
+  activeLanguage = wanted;
+  document.documentElement.lang = wanted;
+}
+
+export function currentLanguage() {
+  return activeLanguage;
+}
+
+/**
+ * Text for a key. Placeholders in braces are replaced: t("runs.count", { n: 3 }).
+ * Values are inserted as plain text - callers put the result into textContent.
+ */
+export function t(key, values = {}) {
+  const text = activePack[key] ?? fallbackPack[key] ?? key;
+  return text.replace(/\{(\w+)\}/g, (match, name) => (name in values ? String(values[name]) : match));
+}
+
+/** Translates static markup: every element with data-i18n gets its text from the pack. */
+export function translateDocument(root = document) {
+  for (const element of root.querySelectorAll("[data-i18n]")) {
+    element.textContent = t(element.dataset.i18n);
+  }
+  for (const element of root.querySelectorAll("[data-i18n-title]")) {
+    element.title = t(element.dataset.i18nTitle);
+  }
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/modules/router.js b/src/ClawdDotNet.Manager.Web/wwwroot/modules/router.js
index 17ee310..c91b733 100644
--- a/src/ClawdDotNet.Manager.Web/wwwroot/modules/router.js
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/modules/router.js
@@ -39,10 +39,24 @@ export function navigiere(hash) {
 
 function parseHash() {
   const hash = window.location.hash || "#/chat";
-  const pfad = hash.startsWith("#") ? hash.slice(1) : hash;
+  let pfad = hash.startsWith("#") ? hash.slice(1) : hash;
+  // #660: Filters travel in the address ("#/verbrauch/runs?agent=x") so a view can be
+  // linked. They are not part of the route pattern.
+  const frage = pfad.indexOf("?");
+  if (frage >= 0) pfad = pfad.slice(0, frage);
   return pfad.startsWith("/") ? pfad : `/${pfad}`;
 }
 
+/**
+ * Query parameters of the current hash address (#660).
+ * @returns {URLSearchParams}
+ */
+export function currentQuery() {
+  const hash = window.location.hash || "";
+  const frage = hash.indexOf("?");
+  return new URLSearchParams(frage >= 0 ? hash.slice(frage + 1) : "");
+}
+
 function findePassendeRoute(pfad) {
   const pfadTeile = pfad.split("/").filter(Boolean);
 
@@ -98,7 +112,15 @@ function aktualisiereAktivenNavEintrag(pfad) {
     const zielPfad = href.startsWith("#") ? href.slice(1) : href;
     const zielBasis = "/" + zielPfad.split("/").filter(Boolean)[0];
 
-    if (basisPfad === zielBasis) {
+    // #660: Sub-entries match their own path (and what lies below it), the parent entry
+    // only its exact path - otherwise "Token usage" and "Runs" would both light up.
+    const treffer = link.classList.contains("nav-unterlink")
+      ? pfad === zielPfad || pfad.startsWith(zielPfad + "/")
+      : link.dataset.exakt !== undefined
+        ? pfad === zielPfad
+        : basisPfad === zielBasis;
+
+    if (treffer) {
       link.classList.add("aktiv");
     } else {
       link.classList.remove("aktiv");
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/modules/usage-filters.js b/src/ClawdDotNet.Manager.Web/wwwroot/modules/usage-filters.js
new file mode 100644
index 0000000..0209749
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/modules/usage-filters.js
@@ -0,0 +1,156 @@
+// ClawdDotNet — filter bar of the usage analysis (#660)
+//
+// The filter lives in the hash address ("#/verbrauch/runs?range=7d&agent=hausmeister"), so a
+// filtered view can be bookmarked and shared, and back/forward work. Each view reads it with
+// readFilters() and writes it with applyFilters().
+
+import { api } from "./api.js";
+import { erstelleElement } from "./dom.js";
+import { currentQuery, navigiere } from "./router.js";
+import { t } from "./i18n.js";
+
+export const RANGES = ["24h", "7d", "30d", "90d", "custom"];
+
+// bucket, groupBy and metric belong to the timeline; the API query ignores them.
+const FILTER_KEYS = ["range", "from", "to", "agent", "model", "source", "status", "minCost", "q", "sort", "dir",
+  "bucket", "groupBy", "metric"];
+
+/** The filter of the current address, with defaults. */
+export function readFilters() {
+  const query = currentQuery();
+  const filters = {};
+  for (const key of FILTER_KEYS) {
+    const value = query.get(key);
+    if (value) filters[key] = value;
+  }
+  filters.range ??= "7d";
+  filters.offset = Number(query.get("offset") || 0);
+  return filters;
+}
+
+/** Navigates to the same view with a new filter. Resets paging unless offset is given. */
+export function applyFilters(path, filters) {
+  const query = new URLSearchParams();
+  for (const [key, value] of Object.entries(filters)) {
+    if (value === undefined || value === null || value === "" || (key === "offset" && !value)) continue;
+    query.set(key, String(value));
+  }
+  const text = query.toString();
+  navigiere(`#${path}${text ? "?" + text : ""}`);
+}
+
+/** Start and end of the selected range as ISO strings (UTC). */
+export function rangeOf(filters) {
+  const now = new Date();
+  if (filters.range === "custom") {
+    // Date inputs are local calendar days; "to" includes the whole day.
+    const from = filters.from ? new Date(`${filters.from}T00:00:00`) : new Date(now.getTime() - 7 * 864e5);
+    const to = filters.to ? new Date(new Date(`${filters.to}T00:00:00`).getTime() + 864e5) : now;
+    return { from: from.toISOString(), to: to.toISOString() };
+  }
+  const hours = { "24h": 24, "7d": 168, "30d": 720, "90d": 2160 }[filters.range] ?? 168;
+  return { from: new Date(now.getTime() - hours * 36e5).toISOString(), to: new Date(now.getTime() + 60e3).toISOString() };
+}
+
+/** Query string for the API: range plus every set filter. */
+export function toApiQuery(filters, extra = {}) {
+  const { from, to } = rangeOf(filters);
+  const query = new URLSearchParams({ from, to });
+  for (const key of ["agent", "model", "source", "status", "minCost", "q", "sort", "dir"]) {
+    if (filters[key]) query.set(key, filters[key]);
+  }
+  for (const [key, value] of Object.entries(extra)) {
+    if (value !== undefined && value !== null && value !== "") query.set(key, String(value));
+  }
+  return query.toString();
+}
+
+export async function loadFacets(filters) {
+  const { from, to } = rangeOf(filters);
+  try {
+    return await api(`/usage/facets?${new URLSearchParams({ from, to })}`);
+  } catch {
+    return { agents: [], models: [], sources: [], statuses: [] };
+  }
+}
+
+function select(name, label, options, current, allText) {
+  const element = erstelleElement("select", { name, "aria-label": label });
+  element.append(erstelleElement("option", { value: "", text: allText }));
+  for (const option of options) {
+    const value = typeof option === "string" ? option : option.value;
+    const text = typeof option === "string" ? option : option.text;
+    element.append(erstelleElement("option", { value, text }));
+  }
+  element.value = current || "";
+  return erstelleElement("label", { klasse: "filter-feld" }, erstelleElement("span", { text: label }), element);
+}
+
+/**
+ * The bar itself. `fields` chooses what is shown, e.g. ["range", "agent", "q"].
+ * `onApply(filters)` receives the complete new filter.
+ */
+export function buildFilterBar(filters, facets, onApply, fields = ["range", "agent", "model", "source", "status", "minCost", "q"]) {
+  const form = erstelleElement("form", { klasse: "filter-leiste" });
+  const show = (field) => fields.includes(field);
+
+  if (show("range")) {
+    form.append(select("range", t("filter.range"),
+      RANGES.map((r) => ({ value: r, text: t(`filter.range.${r}`) })), filters.range, t("filter.range.7d")));
+    const rangeSelect = form.querySelector("select[name=range]");
+    rangeSelect.querySelector("option[value='']").remove();
+
+    const from = erstelleElement("input", { type: "date", name: "from", value: filters.from || "", "aria-label": t("filter.from") });
+    const to = erstelleElement("input", { type: "date", name: "to", value: filters.to || "", "aria-label": t("filter.to") });
+    const custom = erstelleElement("span", { klasse: "filter-eigen" }, from, erstelleElement("span", { text: "–" }), to);
+    custom.hidden = filters.range !== "custom";
+    rangeSelect.addEventListener("change", () => { custom.hidden = rangeSelect.value !== "custom"; });
+    form.append(custom);
+  }
+
+  if (show("agent")) form.append(select("agent", t("filter.agent"), facets.agents ?? [], filters.agent, t("filter.all")));
+  if (show("model")) form.append(select("model", t("filter.model"), facets.models ?? [], filters.model, t("filter.all")));
+  if (show("source")) {
+    form.append(select("source", t("filter.event"),
+      (facets.sources ?? []).map((s) => ({ value: s, text: t(`source.${s}`) === `source.${s}` ? s : t(`source.${s}`) })),
+      filters.source, t("filter.all")));
+  }
+  if (show("status")) form.append(select("status", t("filter.status"), facets.statuses ?? [], filters.status, t("filter.all")));
+
+  if (show("minCost")) {
+    form.append(erstelleElement("label", { klasse: "filter-feld" },
+      erstelleElement("span", { text: t("filter.minCost") }),
+      erstelleElement("input", { type: "number", name: "minCost", min: "0", step: "0.001", value: filters.minCost || "", placeholder: "0.00" })));
+  }
+
+  if (show("q")) {
+    form.append(erstelleElement("label", { klasse: "filter-feld filter-suche" },
+      erstelleElement("span", { text: t("filter.search") }),
+      erstelleElement("input", { type: "search", name: "q", value: filters.q || "", placeholder: t("filter.search.placeholder") })));
+  }
+
+  const apply = erstelleElement("button", { type: "submit", klasse: "schaltflaeche primaer klein", text: t("filter.apply") });
+  const reset = erstelleElement("button", {
+    type: "button",
+    klasse: "schaltflaeche flach klein",
+    text: t("filter.reset"),
+    onclick: () => onApply({ range: "7d" })
+  });
+  form.append(erstelleElement("div", { klasse: "filter-aktionen" }, apply, reset));
+
+  form.addEventListener("submit", (event) => {
+    event.preventDefault();
+    const data = new FormData(form);
+    const next = { sort: filters.sort, dir: filters.dir };
+    for (const [key, value] of data.entries()) {
+      if (value) next[key] = String(value);
+    }
+    if (next.range !== "custom") {
+      delete next.from;
+      delete next.to;
+    }
+    onApply(next);
+  });
+
+  return form;
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/views/prompt-history.js b/src/ClawdDotNet.Manager.Web/wwwroot/views/prompt-history.js
new file mode 100644
index 0000000..8e7b3a9
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/views/prompt-history.js
@@ -0,0 +1,202 @@
+// ClawdDotNet — Analysis › Prompt History (#660)
+//
+// Recorded prompts and responses of every run, searchable over the full transcript, plus
+// how long they are kept: an instance default (14 days unless changed) and an override per
+// agent - "never" for an agent that handles secrets, "forever" or many days to debug one.
+//
+// Transcripts are foreign text and only ever inserted via textContent.
+
+import { api } from "../modules/api.js";
+import { erstelleElement, erstelleKarte, formatiereDatumZeit, formatiereTokens, zeigeMeldung } from "../modules/dom.js";
+import { navigiere } from "../modules/router.js";
+import { t } from "../modules/i18n.js";
+import { readFilters, applyFilters, rangeOf, loadFacets, buildFilterBar } from "../modules/usage-filters.js";
+import { statusBadge, sourceLabel } from "./usage-runs.js";
+
+const PATH = "/prompt-history";
+const PAGE_SIZE = 25;
+const NEVER = 0;
+const FOREVER = -1;
+
+export async function renderPromptHistory() {
+  const container = document.getElementById("ansicht-inhalt");
+  if (!container) return;
+
+  const filters = readFilters();
+  const layout = erstelleElement("div", { klasse: "verbrauch-ansicht" });
+  layout.append(
+    erstelleElement("h1", { text: t("history.title") }),
+    erstelleElement("p", { klasse: "hinweis", text: t("history.intro") }));
+
+  const facets = await loadFacets(filters);
+  layout.append(buildFilterBar(filters, facets, (next) => applyFilters(PATH, next), ["range", "agent", "q"]));
+
+  const list = erstelleElement("div", {}, erstelleElement("div", { klasse: "hinweis-zentriert", text: t("common.loading") }));
+  const settings = erstelleElement("div", {});
+  layout.append(list, settings);
+  container.replaceChildren(layout);
+
+  await Promise.all([loadList(list, filters), loadSettings(settings)]);
+}
+
+async function loadList(target, filters) {
+  const { from, to } = rangeOf(filters);
+  const query = new URLSearchParams({ from, to, offset: String(filters.offset || 0), limit: String(PAGE_SIZE) });
+  if (filters.agent) query.set("agent", filters.agent);
+  if (filters.q) query.set("q", filters.q);
+
+  let page;
+  try {
+    page = await api(`/prompt-history?${query}`);
+  } catch (err) {
+    target.replaceChildren(erstelleKarte(t("history.unavailable"), [erstelleElement("p", { klasse: "gedaempft", text: err.message })]));
+    return;
+  }
+
+  if (page.items.length === 0) {
+    target.replaceChildren(erstelleKarte(t("history.empty.title"), [
+      erstelleElement("p", { klasse: "gedaempft", text: filters.q ? t("history.empty.search") : t("history.empty.text") })
+    ]));
+    return;
+  }
+
+  const items = page.items.map((item) => {
+    const open = () => navigiere(`#${PATH}/${encodeURIComponent(item.runId)}`);
+    const card = erstelleElement("div", { klasse: "verlauf-eintrag klickbar", tabindex: "0", onclick: open });
+    card.addEventListener("keydown", (event) => { if (event.key === "Enter") open(); });
+
+    card.append(
+      erstelleElement("div", { klasse: "verlauf-kopf" },
+        erstelleElement("strong", { text: item.agentId }),
+        erstelleElement("span", { klasse: "gedaempft klein", text: `${formatiereDatumZeit(item.startedAt)} · ${sourceLabel(item.source)} · ${item.model}` }),
+        statusBadge(item.status)),
+      erstelleElement("div", { klasse: "verlauf-zeile" },
+        erstelleElement("span", { klasse: "verlauf-marke", text: t("history.prompt") }),
+        erstelleElement("span", { klasse: "verlauf-text", text: item.prompt || "—" })),
+      erstelleElement("div", { klasse: "verlauf-zeile" },
+        erstelleElement("span", { klasse: "verlauf-marke", text: t("history.response") }),
+        erstelleElement("span", { klasse: "verlauf-text", text: item.response || "—" })));
+
+    if (item.truncated) {
+      card.append(erstelleElement("div", { klasse: "gedaempft klein", text: t("history.truncated", { chars: formatiereTokens(item.sizeChars) }) }));
+    }
+    return card;
+  });
+
+  const offset = filters.offset || 0;
+  const pager = erstelleElement("div", { klasse: "blaettern" },
+    erstelleElement("button", {
+      type: "button", klasse: "schaltflaeche flach klein", text: t("common.previous"), disabled: offset <= 0,
+      onclick: () => applyFilters(PATH, { ...filters, offset: Math.max(0, offset - PAGE_SIZE) })
+    }),
+    erstelleElement("span", { klasse: "gedaempft", text: t("runs.page", { from: offset + 1, to: offset + page.items.length, total: page.total }) }),
+    erstelleElement("button", {
+      type: "button", klasse: "schaltflaeche flach klein", text: t("common.next"), disabled: offset + PAGE_SIZE >= page.total,
+      onclick: () => applyFilters(PATH, { ...filters, offset: offset + PAGE_SIZE })
+    }));
+
+  target.replaceChildren(erstelleKarte(t("history.list", { n: page.total }), [...items, pager]));
+}
+
+// ─── Retention settings ───
+
+function modeOf(days) {
+  if (days === null || days === undefined) return "inherit";
+  if (days === NEVER) return "never";
+  if (days === FOREVER) return "forever";
+  return "days";
+}
+
+/** A mode select plus a day count that is only shown for "days". */
+function retentionInput(days, allowInherit) {
+  const modes = allowInherit ? ["inherit", "never", "days", "forever"] : ["never", "days", "forever"];
+  const mode = erstelleElement("select", { "aria-label": t("history.settings.mode") });
+  for (const m of modes) mode.append(erstelleElement("option", { value: m, text: t(`history.settings.mode.${m}`) }));
+  mode.value = modeOf(days);
+
+  const count = erstelleElement("input", {
+    type: "number", min: "1", step: "1", value: days > 0 ? String(days) : "14", "aria-label": t("history.settings.days")
+  });
+  const unit = erstelleElement("span", { klasse: "gedaempft klein", text: t("history.settings.daysUnit") });
+  const dayBox = erstelleElement("span", { klasse: "gruppe-horizontal" }, count, unit);
+  const sync = () => { dayBox.hidden = mode.value !== "days"; };
+  mode.addEventListener("change", sync);
+  sync();
+
+  return {
+    element: erstelleElement("span", { klasse: "gruppe-horizontal aufbewahrung" }, mode, dayBox),
+    value() {
+      switch (mode.value) {
+        case "inherit": return null;
+        case "never": return NEVER;
+        case "forever": return FOREVER;
+        default: return Math.max(1, Math.round(Number(count.value) || 14));
+      }
+    }
+  };
+}
+
+function describe(days) {
+  if (days === NEVER) return t("history.settings.effective.never");
+  if (days === FOREVER) return t("history.settings.effective.forever");
+  return t("history.settings.effective.days", { n: days });
+}
+
+async function loadSettings(target) {
+  let settings;
+  try {
+    settings = await api("/prompt-history/settings");
+  } catch (err) {
+    target.replaceChildren();
+    return;
+  }
+
+  const instance = retentionInput(settings.defaultRetentionDays, false);
+  const rows = [];
+
+  const table = erstelleElement("table", { klasse: "daten-tabelle" });
+  const head = erstelleElement("tr", {});
+  for (const label of ["history.settings.agent", "history.settings.retention", "history.settings.effective"]) {
+    head.append(erstelleElement("th", { text: t(label) }));
+  }
+  table.append(head);
+
+  for (const agent of settings.agents) {
+    const input = retentionInput(agent.retentionDays, true);
+    rows.push({ agentId: agent.agentId, input, before: agent.retentionDays ?? null });
+    table.append(erstelleElement("tr", {},
+      erstelleElement("td", { text: agent.displayName }),
+      erstelleElement("td", {}, input.element),
+      erstelleElement("td", { klasse: "gedaempft", text: describe(agent.effectiveRetentionDays) })));
+  }
+
+  const save = erstelleElement("button", {
+    type: "button",
+    klasse: "schaltflaeche primaer klein",
+    text: t("history.settings.save"),
+    onclick: async () => {
+      const body = { defaultRetentionDays: instance.value(), agents: [] };
+      for (const row of rows) {
+        const value = row.input.value();
+        if (value !== row.before) body.agents.push({ agentId: row.agentId, retentionDays: value });
+      }
+      save.disabled = true;
+      try {
+        const result = await api("/prompt-history/settings", { method: "PUT", body });
+        zeigeMeldung(result?.message ?? t("history.settings.saved"), "erfolg");
+        await loadSettings(target);
+      } catch (err) {
+        zeigeMeldung(t("history.settings.failed", { error: err.message }), "gefahr");
+        save.disabled = false;
+      }
+    }
+  });
+
+  target.replaceChildren(erstelleKarte(t("history.settings.title"), [
+    erstelleElement("p", { klasse: "hinweis", text: t("history.settings.intro") }),
+    erstelleElement("div", { klasse: "gruppe-horizontal" },
+      erstelleElement("strong", { text: t("history.settings.default") }), instance.element),
+    erstelleElement("div", { klasse: "tabelle-scroll" }, table),
+    save
+  ]));
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/views/run-detail.js b/src/ClawdDotNet.Manager.Web/wwwroot/views/run-detail.js
new file mode 100644
index 0000000..5b07683
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/views/run-detail.js
@@ -0,0 +1,195 @@
+// ClawdDotNet — run detail: prompt, response and every step in between (#660)
+//
+// Reached from Token usage › Runs and from Prompt History. Shows the receipt, the recorded
+// transcript (task, each model step with its tokens and cost, each tool call and result),
+// the system prompt, and what the run proposed for approval.
+//
+// Everything in a transcript is foreign text - model output, web pages, database rows.
+// It is only ever inserted via textContent.
+
+import { api } from "../modules/api.js";
+import {
+  erstelleElement,
+  erstelleKarte,
+  erstellePlakette,
+  formatiereDatumZeit,
+  formatiereTokens,
+  formatiereKosten
+} from "../modules/dom.js";
+import { t } from "../modules/i18n.js";
+import { statusBadge, sourceLabel, formatDuration } from "./usage-runs.js";
+
+export async function renderRunDetail(runId, backPath) {
+  const container = document.getElementById("ansicht-inhalt");
+  if (!container) return;
+
+  const back = erstelleElement("a", { href: `#${backPath}`, klasse: "zurueck-link", text: t("detail.back") });
+  // Back to the filtered list if we came from one.
+  back.addEventListener("click", (event) => {
+    if (window.history.length > 1) {
+      event.preventDefault();
+      window.history.back();
+    }
+  });
+
+  const layout = erstelleElement("div", { klasse: "verbrauch-ansicht lauf-detail" }, back,
+    erstelleElement("h1", { text: t("detail.title") }),
+    erstelleElement("div", { klasse: "hinweis-zentriert", text: t("common.loading") }));
+  container.replaceChildren(layout);
+
+  let run;
+  try {
+    run = await api(`/runs/${encodeURIComponent(runId)}`);
+  } catch (err) {
+    layout.lastChild.replaceWith(erstelleKarte(t("detail.notFound"), [
+      erstelleElement("p", { klasse: "gedaempft", text: err.message })
+    ]));
+    return;
+  }
+
+  const parts = [buildReceipt(run)];
+  parts.push(run.transcript ? buildTranscript(run) : buildTranscriptState(run));
+  if (!run.transcript && run.toolCalls.length > 0) parts.push(buildToolCalls(run.toolCalls));
+  if (run.approvals.length > 0) parts.push(buildApprovals(run.approvals));
+
+  layout.lastChild.replaceWith(...parts);
+}
+
+function buildReceipt(run) {
+  const r = run.receipt;
+  const list = erstelleElement("dl", { klasse: "datenliste" });
+  const add = (label, value) => list.append(
+    erstelleElement("dt", { text: t(label) }),
+    value instanceof Node ? erstelleElement("dd", {}, value) : erstelleElement("dd", { text: value ?? "—" }));
+
+  add("detail.runId", run.runId);
+  if (r) {
+    add("runs.col.time", formatiereDatumZeit(r.occurredAt));
+    add("runs.col.agent", r.agentId);
+    add("runs.col.model", r.model);
+    add("runs.col.event", r.taskTitle ? `${sourceLabel(r.source)} · ${r.taskTitle}` : sourceLabel(r.source));
+    add("runs.col.status", statusBadge(r.status));
+    add("runs.col.steps", String(r.stepCount));
+    add("detail.tokens", t("detail.tokensValue", {
+      prompt: formatiereTokens(r.promptTokens),
+      completion: formatiereTokens(r.completionTokens),
+      cached: formatiereTokens(r.cachedTokens)
+    }));
+    add("runs.col.cost", r.costIsKnown || r.costUsd > 0 ? formatiereKosten(r.costUsd) : "—");
+    add("runs.col.duration", formatDuration(r.durationMs));
+    if (r.result) add("detail.result", r.result);
+  }
+  return erstelleKarte(t("detail.receipt"), [list]);
+}
+
+function buildTranscriptState(run) {
+  const text = {
+    disabled: t("detail.transcript.disabled"),
+    unavailable: t("detail.transcript.unavailable"),
+    missing: t("detail.transcript.missing")
+  }[run.transcriptState] ?? t("detail.transcript.missing");
+  return erstelleKarte(t("detail.transcript"), [erstelleElement("p", { klasse: "gedaempft", text })]);
+}
+
+function pre(text) {
+  return erstelleElement("pre", { klasse: "code-block transkript-text", text: text ?? "" });
+}
+
+function prettyJson(text) {
+  if (!text) return "";
+  try {
+    return JSON.stringify(JSON.parse(text), null, 2);
+  } catch {
+    return text;
+  }
+}
+
+function buildTranscript(run) {
+  const transcript = run.transcript;
+  const items = [];
+
+  if (run.systemPrompt) {
+    const details = erstelleElement("details", { klasse: "transkript-system" },
+      erstelleElement("summary", { text: t("detail.systemPrompt", { n: run.systemPrompt.length }) }),
+      pre(run.systemPrompt));
+    items.push(details);
+  }
+
+  if (transcript.truncated) {
+    items.push(erstelleElement("div", { klasse: "hinweis-box warnung", text: t("detail.transcript.truncated") }));
+  }
+
+  let step = 0;
+  for (const entry of transcript.entries) {
+    const kind = entry.kind;
+    const block = erstelleElement("div", { klasse: `transkript-eintrag art-${kind}` });
+    const head = erstelleElement("div", { klasse: "transkript-kopf" });
+
+    if (kind === "assistant") {
+      step++;
+      head.append(erstelleElement("strong", { text: t("detail.entry.assistant", { n: step }) }));
+      if (entry.promptTokens !== undefined && entry.promptTokens !== null) {
+        head.append(erstellePlakette(t("detail.entry.usage", {
+          prompt: formatiereTokens(entry.promptTokens),
+          completion: formatiereTokens(entry.completionTokens ?? 0)
+        }), "neutral"));
+      }
+      if (entry.costUsd) head.append(erstellePlakette(formatiereKosten(entry.costUsd), "neutral"));
+      if (entry.finishReason && entry.finishReason !== "stop" && entry.finishReason !== "tool_calls") {
+        head.append(erstellePlakette(entry.finishReason, "warnung"));
+      }
+    } else {
+      head.append(erstelleElement("strong", {
+        text: kind === "tool_result"
+          ? t("detail.entry.tool_result", { tool: entry.toolName ?? "?" })
+          : t(`detail.entry.${kind}`)
+      }));
+    }
+    head.append(erstelleElement("span", { klasse: "gedaempft klein", text: formatiereDatumZeit(entry.at) }));
+    if (entry.clipped) head.append(erstellePlakette(t("detail.entry.clipped"), "warnung"));
+    block.append(head);
+
+    if (entry.text) block.append(pre(entry.text));
+
+    for (const call of entry.toolCalls ?? []) {
+      block.append(erstelleElement("div", { klasse: "transkript-aufruf" },
+        erstelleElement("span", { klasse: "klein", text: t("detail.entry.call", { tool: call.name }) }),
+        pre(prettyJson(call.arguments))));
+    }
+
+    items.push(block);
+  }
+
+  const summary = t("detail.transcript.size", { n: transcript.entries.length, chars: formatiereTokens(transcript.sizeChars) });
+  return erstelleKarte(t("detail.transcript"), [erstelleElement("p", { klasse: "hinweis", text: summary }), ...items]);
+}
+
+function buildToolCalls(calls) {
+  const table = erstelleElement("table", { klasse: "daten-tabelle" });
+  const head = erstelleElement("tr", {});
+  for (const label of ["runs.col.time", "detail.tool", "runs.col.status", "detail.arguments"]) {
+    head.append(erstelleElement("th", { text: t(label) }));
+  }
+  table.append(head);
+  for (const call of calls) {
+    table.append(erstelleElement("tr", {},
+      erstelleElement("td", { text: formatiereDatumZeit(call.at) }),
+      erstelleElement("td", { text: call.tool }),
+      erstelleElement("td", { text: call.status }),
+      erstelleElement("td", {}, pre(prettyJson(call.arguments)))));
+  }
+  return erstelleKarte(t("detail.toolCalls"), [
+    erstelleElement("p", { klasse: "hinweis", text: t("detail.toolCalls.hint") }),
+    erstelleElement("div", { klasse: "tabelle-scroll" }, table)
+  ]);
+}
+
+function buildApprovals(approvals) {
+  const list = erstelleElement("ul", { klasse: "schlichte-liste" });
+  for (const a of approvals) {
+    list.append(erstelleElement("li", {},
+      erstelleElement("strong", { text: `#${a.id} ${a.tool}.${a.action ?? "?"} ` }),
+      erstellePlakette(a.status, a.status === "Executed" ? "erfolg" : a.status === "Pending" ? "warnung" : "neutral")));
+  }
+  return erstelleKarte(t("detail.approvals"), [list]);
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-runs.js b/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-runs.js
new file mode 100644
index 0000000..4c9d9a5
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-runs.js
@@ -0,0 +1,187 @@
+// ClawdDotNet — Token usage › Runs (#660)
+//
+// Every run of the selected range: filterable by agent, model, event (source), status,
+// cost and free text; sortable by every column; totals over the whole filter, not only
+// the visible page. A row opens the run detail with prompt and response.
+//
+// Strictly DOM API, no innerHTML: results and task titles are foreign text.
+
+import { api } from "../modules/api.js";
+import {
+  erstelleElement,
+  erstelleKarte,
+  erstellePlakette,
+  formatiereDatumZeit,
+  formatiereTokens,
+  formatiereKosten
+} from "../modules/dom.js";
+import { navigiere } from "../modules/router.js";
+import { t } from "../modules/i18n.js";
+import { readFilters, applyFilters, toApiQuery, loadFacets, buildFilterBar } from "../modules/usage-filters.js";
+
+const PATH = "/verbrauch/runs";
+const PAGE_SIZE = 50;
+
+const COLUMNS = [
+  { key: "time", label: "runs.col.time" },
+  { key: "agent", label: "runs.col.agent" },
+  { key: "model", label: "runs.col.model" },
+  { key: "source", label: "runs.col.event" },
+  { key: "status", label: "runs.col.status" },
+  { key: "steps", label: "runs.col.steps", numeric: true },
+  { key: "prompt", label: "runs.col.prompt", numeric: true },
+  { key: "completion", label: "runs.col.completion", numeric: true },
+  { key: "cost", label: "runs.col.cost", numeric: true },
+  { key: "duration", label: "runs.col.duration", numeric: true }
+];
+
+export function statusBadge(status) {
+  const kind = {
+    Completed: "erfolg",
+    BudgetExceeded: "warnung",
+    Truncated: "warnung",
+    LoopLimitExceeded: "gefahr",
+    RepeatedFailure: "gefahr",
+    Failed: "gefahr",
+    Cancelled: "neutral"
+  }[status] ?? "neutral";
+  return erstellePlakette(status, kind);
+}
+
+export function sourceLabel(source) {
+  const key = `source.${source}`;
+  const text = t(key);
+  return text === key ? source : text;
+}
+
+export async function renderUsageRuns() {
+  const container = document.getElementById("ansicht-inhalt");
+  if (!container) return;
+
+  const filters = readFilters();
+  filters.sort ??= "time";
+  filters.dir ??= "desc";
+
+  const layout = erstelleElement("div", { klasse: "verbrauch-ansicht" });
+  layout.append(erstelleElement("h1", { text: t("runs.title") }));
+
+  const facets = await loadFacets(filters);
+  layout.append(buildFilterBar(filters, facets, (next) => applyFilters(PATH, next)));
+
+  const content = erstelleElement("div", {}, erstelleElement("div", { klasse: "hinweis-zentriert", text: t("common.loading") }));
+  layout.append(content);
+  container.replaceChildren(layout);
+
+  let page;
+  try {
+    page = await api(`/usage/runs?${toApiQuery(filters, { offset: filters.offset, limit: PAGE_SIZE })}`);
+  } catch (err) {
+    content.replaceChildren(erstelleKarte(t("runs.unavailable"), [
+      erstelleElement("p", { klasse: "gedaempft", text: err.message })
+    ]));
+    return;
+  }
+
+  content.replaceChildren(buildTotals(page.totals), buildTable(page, filters));
+}
+
+function buildTotals(totals) {
+  const tiles = [
+    [t("runs.total.runs"), String(totals.runs)],
+    [t("runs.total.prompt"), formatiereTokens(totals.promptTokens)],
+    [t("runs.total.completion"), formatiereTokens(totals.completionTokens)],
+    [t("runs.total.cached"), formatiereTokens(totals.cachedTokens)],
+    [t("runs.total.cost"), formatiereKosten(totals.costUsd)],
+    [t("runs.total.notRun"), String(totals.notRun)]
+  ];
+
+  const grid = erstelleElement("div", { klasse: "kennzahlen-raster" });
+  for (const [label, value] of tiles) {
+    grid.append(erstelleElement("div", { klasse: "kennzahl" },
+      erstelleElement("div", { klasse: "kennzahl-wert", text: value }),
+      erstelleElement("div", { klasse: "kennzahl-titel", text: label })));
+  }
+
+  const parts = [grid];
+  if (totals.runsWithUnknownCost > 0) {
+    parts.push(erstelleElement("p", { klasse: "hinweis", text: t("runs.unknownCost", { n: totals.runsWithUnknownCost }) }));
+  }
+  return erstelleKarte(t("runs.totals"), parts);
+}
+
+function buildTable(page, filters) {
+  if (page.items.length === 0) {
+    return erstelleKarte(t("runs.empty.title"), [erstelleElement("p", { klasse: "gedaempft", text: t("runs.empty.text") })]);
+  }
+
+  const table = erstelleElement("table", { klasse: "daten-tabelle lauf-tabelle" });
+  const head = erstelleElement("tr", {});
+  for (const column of COLUMNS) {
+    const active = filters.sort === column.key;
+    const arrow = active ? (filters.dir === "asc" ? " ▲" : " ▼") : "";
+    const button = erstelleElement("button", {
+      type: "button",
+      klasse: "sortier-knopf",
+      text: t(column.label) + arrow,
+      onclick: () => applyFilters(PATH, {
+        ...filters,
+        offset: 0,
+        sort: column.key,
+        dir: active && filters.dir === "desc" ? "asc" : "desc"
+      })
+    });
+    head.append(erstelleElement("th", { klasse: column.numeric ? "zahl" : "", "aria-sort": active ? (filters.dir === "asc" ? "ascending" : "descending") : "none" }, button));
+  }
+  table.append(erstelleElement("thead", {}, head));
+
+  const body = erstelleElement("tbody", {});
+  for (const run of page.items) {
+    const open = () => navigiere(`#${PATH}/${encodeURIComponent(run.runId)}`);
+    const row = erstelleElement("tr", { klasse: "klickbar", tabindex: "0", onclick: open });
+    row.addEventListener("keydown", (event) => { if (event.key === "Enter") open(); });
+
+    const event = erstelleElement("td", {}, erstelleElement("div", { text: sourceLabel(run.source) }));
+    if (run.taskTitle || run.taskId) {
+      event.append(erstelleElement("div", { klasse: "gedaempft klein", text: run.taskTitle || run.taskId }));
+    }
+
+    row.append(
+      erstelleElement("td", { text: formatiereDatumZeit(run.occurredAt) }),
+      erstelleElement("td", { text: run.agentId }),
+      erstelleElement("td", { klasse: "klein", text: run.model || "—" }),
+      event,
+      erstelleElement("td", {}, statusBadge(run.status)),
+      erstelleElement("td", { klasse: "zahl", text: String(run.stepCount) }),
+      erstelleElement("td", { klasse: "zahl", text: formatiereTokens(run.promptTokens) }),
+      erstelleElement("td", { klasse: "zahl", text: formatiereTokens(run.completionTokens) }),
+      erstelleElement("td", { klasse: "zahl", text: run.costIsKnown || run.costUsd > 0 ? formatiereKosten(run.costUsd) : "—" }),
+      erstelleElement("td", { klasse: "zahl", text: formatDuration(run.durationMs) })
+    );
+    body.append(row);
+  }
+  table.append(body);
+
+  const offset = filters.offset || 0;
+  const pager = erstelleElement("div", { klasse: "blaettern" },
+    erstelleElement("button", {
+      type: "button", klasse: "schaltflaeche flach klein", text: t("common.previous"), disabled: offset <= 0,
+      onclick: () => applyFilters(PATH, { ...filters, offset: Math.max(0, offset - PAGE_SIZE) })
+    }),
+    erstelleElement("span", {
+      klasse: "gedaempft",
+      text: t("runs.page", { from: offset + 1, to: offset + page.items.length, total: page.total })
+    }),
+    erstelleElement("button", {
+      type: "button", klasse: "schaltflaeche flach klein", text: t("common.next"), disabled: offset + PAGE_SIZE >= page.total,
+      onclick: () => applyFilters(PATH, { ...filters, offset: offset + PAGE_SIZE })
+    }));
+
+  return erstelleKarte(t("runs.list"), [erstelleElement("div", { klasse: "tabelle-scroll" }, table), pager]);
+}
+
+export function formatDuration(ms) {
+  if (!ms) return "—";
+  if (ms < 1000) return `${ms} ms`;
+  const seconds = ms / 1000;
+  return seconds < 60 ? `${seconds.toFixed(1)} s` : `${Math.floor(seconds / 60)}:${String(Math.round(seconds % 60)).padStart(2, "0")} min`;
+}
diff --git a/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-timeline.js b/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-timeline.js
new file mode 100644
index 0000000..d29d8d4
--- /dev/null
+++ b/src/ClawdDotNet.Manager.Web/wwwroot/views/usage-timeline.js
@@ -0,0 +1,234 @@
+// ClawdDotNet — Token usage › Timeline (#660)
+//
+// Stacked bars per hour or day, grouped by agent, model or event, measuring cost, tokens or
+// runs. Budget denials and model changes are drawn as markers on the axis - the usual
+// explanation for a jump. Clicking a bar opens the runs of exactly that bucket and group.
+//
+// Inline SVG built with the DOM API: the manager runs offline, no chart library.
+
+import { api } from "../modules/api.js";
+import { erstelleElement, erstelleKarte, formatiereTokens, formatiereKosten } from "../modules/dom.js";
+import { t } from "../modules/i18n.js";
+import { readFilters, applyFilters, toApiQuery, loadFacets, buildFilterBar, rangeOf } from "../modules/usage-filters.js";
+import { sourceLabel } from "./usage-runs.js";
+
+const PATH = "/verbrauch/timeline";
+const SVG = "http://www.w3.org/2000/svg";
+
+// Distinguishable in light and dark theme; repeats after ten groups.
+const PALETTE = ["#4e79a7", "#f28e2b", "#59a14f", "#e15759", "#76b7b2", "#edc948", "#b07aa1", "#ff9da7", "#9c755f", "#bab0ac"];
+
+function svg(tag, attributes = {}, ...children) {
+  const element = document.createElementNS(SVG, tag);
+  for (const [key, value] of Object.entries(attributes)) element.setAttribute(key, String(value));
+  for (const child of children) element.append(child);
+  return element;
+}
+
+function title(text) {
+  const element = document.createElementNS(SVG, "title");
+  element.textContent = text;
+  return element;
+}
+
+export async function renderUsageTimeline() {
+  const container = document.getElementById("ansicht-inhalt");
+  if (!container) return;
+
+  const filters = readFilters();
+  const bucket = filters.bucket ?? (["24h", "7d"].includes(filters.range) ? "hour" : "day");
+  const groupBy = filters.groupBy ?? "agent";
+  const metric = filters.metric ?? "cost";
+
+  const layout = erstelleElement("div", { klasse: "verbrauch-ansicht" });
+  layout.append(erstelleElement("h1", { text: t("timeline.title") }));
+
+  const facets = await loadFacets(filters);
+  layout.append(buildFilterBar(filters, facets, (next) => applyFilters(PATH, { ...next, bucket, groupBy, metric })));
+  layout.append(buildControls(filters, bucket, groupBy, metric));
+
+  const content = erstelleElement("div", {}, erstelleElement("div", { klasse: "hinweis-zentriert", text: t("common.loading") }));
+  layout.append(content);
+  container.replaceChildren(layout);
+
+  let points;
+  let events;
+  try {
+    const tzOffset = -new Date().getTimezoneOffset();
+    [points, events] = await Promise.all([
+      api(`/usage/series?${toApiQuery(filters, { bucket, groupBy, tzOffset })}`),
+      api(`/usage/events?${toApiQuery(filters)}`)
+    ]);
+  } catch (err) {
+    content.replaceChildren(erstelleKarte(t("runs.unavailable"), [erstelleElement("p", { klasse: "gedaempft", text: err.message })]));
+    return;
+  }
+
+  if (points.length === 0) {
+    content.replaceChildren(erstelleKarte(t("runs.empty.title"), [erstelleElement("p", { klasse: "gedaempft", text: t("runs.empty.text") })]));
+    return;
+  }
+
+  content.replaceChildren(buildChart(points, events, filters, bucket, groupBy, metric));
+}
+
+function buildControls(filters, bucket, groupBy, metric) {
+  const bar = erstelleElement("div", { klasse: "reiter-leiste diagramm-steuerung" });
+
+  const group = (name, options, current) => {
+    const wrapper = erstelleElement("div", { klasse: "gruppe-horizontal" },
+      erstelleElement("span", { klasse: "gedaempft klein", text: t(`timeline.${name}`) }));
+    for (const option of options) {
+      wrapper.append(erstelleElement("button", {
+        type: "button",
+        klasse: `reiter-schaltflaeche${option === current ? " aktiv" : ""}`,
+        text: t(`timeline.${name}.${option}`),
+        onclick: () => applyFilters(PATH, { ...readFilters(), bucket, groupBy, metric, [name]: option })
+      }));
+    }
+    return wrapper;
+  };
+
+  bar.append(
+    group("metric", ["cost", "tokens", "runs"], metric),
+    group("groupBy", ["agent", "model", "source"], groupBy),
+    group("bucket", ["hour", "day"], bucket));
+  return bar;
+}
+
+function bucketsBetween(from, to, bucket) {
+  const step = bucket === "day" ? 864e5 : 36e5;
+  const start = new Date(from);
+  if (bucket === "day") start.setHours(0, 0, 0, 0);
+  else start.setMinutes(0, 0, 0);
+  const list = [];
+  for (let time = start.getTime(); time < new Date(to).getTime() && list.length < 2000; time += step) {
+    list.push(time);
+  }
+  return list;
+}
+
+function formatBucket(time, bucket) {
+  const date = new Date(time);
+  return bucket === "day"
+    ? date.toLocaleDateString(undefined, { day: "2-digit", month: "2-digit" })
+    : date.toLocaleString(undefined, { day: "2-digit", month: "2-digit", hour: "2-digit", minute: "2-digit" });
+}
+
+function formatValue(value, metric) {
+  return metric === "cost" ? formatiereKosten(value) : metric === "tokens" ? formatiereTokens(value) : String(value);
+}
+
+function buildChart(points, events, filters, bucket, groupBy, metric) {
+  const valueOf = (p) => (metric === "cost" ? Number(p.costUsd) : metric === "tokens" ? p.tokens : p.runs);
+  const { from, to } = rangeOf(filters);
+
+  // The API only returns buckets that have runs; the axis shows the whole range.
+  const firstPoint = Math.min(...points.map((p) => new Date(p.bucketStart).getTime()));
+  const buckets = bucketsBetween(Math.min(new Date(from).getTime(), firstPoint), to, bucket);
+  const step = bucket === "day" ? 864e5 : 36e5;
+  const indexOf = (time) => Math.floor((time - buckets[0]) / step);
+
+  const groups = [...new Set(points.map((p) => p.group))].sort();
+  const color = (group) => PALETTE[groups.indexOf(group) % PALETTE.length];
+
+  const stacks = buckets.map(() => []);
+  for (const p of points) {
+    const i = indexOf(new Date(p.bucketStart).getTime());
+    if (i >= 0 && i < stacks.length) stacks[i].push(p);
+  }
+  const max = Math.max(...stacks.map((s) => s.reduce((sum, p) => sum + valueOf(p), 0)), 0) || 1;
+
+  const barWidth = Math.max(4, Math.min(28, Math.floor(1100 / buckets.length)));
+  const left = 70;
+  const top = 16;
+  const height = 260;
+  const width = left + buckets.length * barWidth + 20;
+  const chart = svg("svg", {
+    class: "zeitverlauf",
+    viewBox: `0 0 ${width} ${height + top + 50}`,
+    width,
+    height: height + top + 50,
+    role: "img",
+    "aria-label": t("timeline.title")
+  });
+
+  // Axis and grid: four lines with the value.
+  for (let i = 0; i <= 4; i++) {
+    const y = top + height - (height * i) / 4;
+    chart.append(svg("line", { x1: left, x2: width - 10, y1: y, y2: y, class: "raster" }));
+    const label = svg("text", { x: left - 6, y: y + 4, "text-anchor": "end", class: "achse" });
+    label.textContent = formatValue((max * i) / 4, metric);
+    chart.append(label);
+  }
+
+  const labelEvery = Math.ceil(buckets.length / 12);
+  stacks.forEach((stack, i) => {
+    const x = left + i * barWidth;
+    let y = top + height;
+    for (const p of stack) {
+      const h = (valueOf(p) / max) * height;
+      if (h <= 0) continue;
+      y -= h;
+      const rect = svg("rect", {
+        x: x + 1, y, width: barWidth - 2, height: h, fill: color(p.group), class: "balken", tabindex: 0
+      }, title(`${formatBucket(buckets[i], bucket)} · ${groupBy === "source" ? sourceLabel(p.group) : p.group}: ` +
+        `${formatValue(valueOf(p), metric)} (${t("timeline.tooltipRuns", { n: p.runs })})`));
+      rect.addEventListener("click", () => openBucket(filters, buckets[i], step, groupBy, p.group));
+      chart.append(rect);
+    }
+    if (i % labelEvery === 0) {
+      const label = svg("text", { x: x + barWidth / 2, y: top + height + 16, "text-anchor": "middle", class: "achse" });
+      label.textContent = formatBucket(buckets[i], bucket);
+      chart.append(label);
+    }
+  });
+
+  for (const event of events) {
+    const time = new Date(event.at).getTime();
+    const i = (time - buckets[0]) / step;
+    if (i < 0 || i > buckets.length) continue;
+    const x = left + i * barWidth;
+    const kind = event.kind === "budget_exceeded" ? "ereignis-budget" : "ereignis-modell";
+    chart.append(svg("g", { class: `ereignis ${kind}` },
+      svg("line", { x1: x, x2: x, y1: top, y2: top + height }),
+      svg("path", { d: `M${x - 5},${top + height + 22} L${x + 5},${top + height + 22} L${x},${top + height + 30} Z` }),
+      title(`${new Date(event.at).toLocaleString()} · ${event.agentId}: ${t(`timeline.event.${event.kind}`)} – ${event.text}`)));
+  }
+
+  const legend = erstelleElement("div", { klasse: "legende" });
+  for (const group of groups) {
+    const total = points.filter((p) => p.group === group).reduce((sum, p) => sum + valueOf(p), 0);
+    legend.append(erstelleElement("span", { klasse: "legende-eintrag" },
+      erstelleElement("span", { klasse: "legende-farbe", stil: { background: color(group) } }),
+      erstelleElement("span", { text: `${groupBy === "source" ? sourceLabel(group) : group}: ${formatValue(total, metric)}` })));
+  }
+  if (events.length > 0) {
+    legend.append(
+      erstelleElement("span", { klasse: "legende-eintrag" },
+        erstelleElement("span", { klasse: "legende-marke ereignis-budget" }),
+        erstelleElement("span", { text: t("timeline.event.budget_exceeded") })),
+      erstelleElement("span", { klasse: "legende-eintrag" },
+        erstelleElement("span", { klasse: "legende-marke ereignis-modell" }),
+        erstelleElement("span", { text: t("timeline.event.model_changed") })));
+  }
+
+  return erstelleKarte(t("timeline.chart"), [
+    erstelleElement("div", { klasse: "diagramm-scroll" }, chart),
+    legend,
+    erstelleElement("p", { klasse: "hinweis", text: t("timeline.hint") })
+  ]);
+}
+
+function openBucket(filters, start, step, groupBy, group) {
+  const day = (time) => {
+    const d = new Date(time);
+    return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, "0")}-${String(d.getDate()).padStart(2, "0")}`;
+  };
+  const next = { ...filters, range: "custom", from: day(start), to: day(start + step - 1), offset: 0 };
+  delete next.bucket;
+  delete next.groupBy;
+  delete next.metric;
+  next[groupBy === "source" ? "source" : groupBy] = group;
+  applyFilters("/verbrauch/runs", next);
+}
diff --git a/src/ClawdDotNet.Web/Endpoints/AnalyticsEndpoints.cs b/src/ClawdDotNet.Web/Endpoints/AnalyticsEndpoints.cs
new file mode 100644
index 0000000..3b1bb09
--- /dev/null
+++ b/src/ClawdDotNet.Web/Endpoints/AnalyticsEndpoints.cs
@@ -0,0 +1,279 @@
+using ClawdDotNet.App;
+using ClawdDotNet.App.Services;
+using ClawdDotNet.Core.Analytics;
+using ClawdDotNet.Core.Transcripts;
+using ClawdDotNet.Web.Contracts;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+
+namespace ClawdDotNet.Web.Endpoints;
+
+/// <summary>
+/// Usage analysis and prompt history (#660).
+///
+/// <list type="bullet">
+/// <item><c>GET /api/usage/runs</c> - filterable, sortable, paged list of runs with totals over the whole filter</item>
+/// <item><c>GET /api/usage/series</c> - stacked buckets per hour or day for the timeline</item>
+/// <item><c>GET /api/usage/events</c> - markers for the timeline (budget denials, model changes)</item>
+/// <item><c>GET /api/usage/facets</c> - the values the filter dropdowns offer</item>
+/// <item><c>GET /api/runs/{runId}</c> - one run: receipt, tool calls, approvals, transcript</item>
+/// <item><c>GET /api/prompt-history</c> - recorded transcripts with full-text search</item>
+/// <item><c>GET|PUT /api/prompt-history/settings</c> - retention per instance and per agent</item>
+/// </list>
+///
+/// Filters use the same query parameters everywhere: <c>from</c>, <c>to</c> (ISO 8601),
+/// <c>agent</c>, <c>model</c>, <c>source</c>, <c>status</c> (comma separated),
+/// <c>minCost</c>, <c>q</c>. Without <c>from</c> the last 7 days are shown.
+/// </summary>
+public static class AnalyticsEndpoints
+{
+    private static readonly TimeSpan DefaultRange = TimeSpan.FromDays(7);
+
+    public static void MapAnalytics(this RouteGroupBuilder api)
+    {
+        api.MapGet("/usage/runs", async (AppHost host, HttpRequest request, CancellationToken ct) =>
+        {
+            if (host.Insights is not { } insights)
+                return ApiEndpoints.Unavailable("No usage data: agents are not active.");
+
+            var page = await insights.Analytics.QueryRunsAsync(ParseQuery(request), ct);
+            return Results.Ok(new RunPageDto(
+                page.Items.Select(ToDto).ToList(),
+                page.Total,
+                new RunTotalsDto(page.Totals.Runs, page.Totals.PromptTokens, page.Totals.CompletionTokens,
+                    page.Totals.CachedTokens, page.Totals.CostUsd, page.Totals.RunsWithUnknownCost, page.Totals.NotRun)));
+        });
+
+        api.MapGet("/usage/series", async (
+            AppHost host, HttpRequest request, CancellationToken ct,
+            string bucket = "hour", string groupBy = "agent", int tzOffset = 0) =>
+        {
+            if (host.Insights is not { } insights)
+                return ApiEndpoints.Unavailable("No usage data: agents are not active.");
+
+            var points = await insights.Analytics.SeriesAsync(
+                ParseQuery(request),
+                bucket == "day" ? "day" : "hour",
+                groupBy is "model" or "source" ? groupBy : "agent",
+                TimeSpan.FromMinutes(Math.Clamp(tzOffset, -14 * 60, 14 * 60)),
+                ct);
+            return Results.Ok(points.Select(p => new SeriesPointDto(p.BucketStart, p.Group, p.Runs, p.Tokens, p.CostUsd)).ToList());
+        });
+
+        api.MapGet("/usage/events", async (AppHost host, HttpRequest request, CancellationToken ct) =>
+        {
+            if (host.Insights is not { } insights)
+                return ApiEndpoints.Unavailable("No usage data: agents are not active.");
+
+            var (from, to) = ParseRange(request);
+            var events = await insights.Analytics.EventsAsync(from, to, ct);
+            return Results.Ok(events.Select(e => new UsageEventDto(e.At, e.Kind, e.AgentId, e.Text)).ToList());
+        });
+
+        api.MapGet("/usage/facets", async (AppHost host, HttpRequest request, CancellationToken ct) =>
+        {
+            if (host.Insights is not { } insights)
+                return ApiEndpoints.Unavailable("No usage data: agents are not active.");
+
+            var (from, to) = ParseRange(request);
+            var f = await insights.Analytics.FacetsAsync(from, to, ct);
+            return Results.Ok(new UsageFacetsDto(f.Agents, f.Models, f.Sources, f.Statuses));
+        });
+
+        api.MapGet("/runs/{runId}", async (AppHost host, string runId, CancellationToken ct) =>
+        {
+            if (host.Insights is not { } insights)
+                return ApiEndpoints.Unavailable("No usage data: agents are not active.");
+
+            return await insights.GetRunAsync(runId, ct) is { } detail
+                ? Results.Ok(ToDto(detail))
+                : Results.NotFound(new OutcomeDto(false, $"No run with id '{runId}'."));
+        });
+
+        api.MapGet("/prompt-history", async (
+            AppHost host, HttpRequest request, CancellationToken ct, int offset = 0, int limit = 50) =>
+        {
+            if (host.Insights?.Transcripts is not { } store)
+                return ApiEndpoints.Unavailable("Prompt history is not available in this instance.");
+
+            var (from, to) = ParseRange(request);
+            var (items, total) = await store.ListAsync(new TranscriptQuery
+            {
+                AgentId = request.Query["agent"].FirstOrDefault(),
+                From = from,
+                To = to,
+                Search = request.Query["q"].FirstOrDefault(),
+                Offset = offset,
+                Limit = limit
+            }, ct);
+
+            return Results.Ok(new TranscriptPageDto(items.Select(i => new TranscriptSummaryDto(
+                i.RunId, i.AgentId, i.Model, i.Source, i.TaskId, i.StartedAt, i.CompletedAt,
+                i.Status, i.Prompt, i.Response, i.SizeChars, i.Truncated)).ToList(), total));
+        });
+
+        api.MapGet("/prompt-history/settings", (AppHost host) => Results.Ok(SettingsDto(host)));
+
+        api.MapPut("/prompt-history/settings", (AppHost host, PromptHistorySettingsInputDto input) =>
+        {
+            var messages = new List<string>();
+
+            if (input.DefaultRetentionDays is { } days)
+            {
+                var result = host.AgentAdmin.SetDefaultPromptHistoryRetention(days);
+                if (!result.Ok) return result.ToResponse();
+                messages.Add(result.Message);
+            }
+
+            foreach (var agent in input.Agents ?? [])
+            {
+                var result = host.AgentAdmin.SetPromptHistoryRetention(agent.AgentId, agent.RetentionDays);
+                if (!result.Ok) return result.ToResponse();
+                messages.Add(result.Message);
+            }
+
+            return Results.Ok(new OutcomeDto(true, messages.Count == 0 ? "Nothing changed." : string.Join(" ", messages)));
+        });
+    }
+
+    // ─── Parsing ───
+
+    internal static (DateTime From, DateTime To) ParseRange(HttpRequest request)
+    {
+        var to = ParseDate(request.Query["to"].FirstOrDefault()) ?? DateTime.UtcNow.AddMinutes(1);
+        var from = ParseDate(request.Query["from"].FirstOrDefault()) ?? to - DefaultRange;
+        return (from, to);
+    }
+
+    internal static RunQuery ParseQuery(HttpRequest request)
+    {
+        var (from, to) = ParseRange(request);
+        var query = request.Query;
+
+        static IReadOnlyCollection<string> List(string? value)
+            => string.IsNullOrWhiteSpace(value)
+                ? []
+                : value.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries).ToHashSet();
+
+        return new RunQuery
+        {
+            FromUtc = from,
+            ToUtc = to,
+            Agents = List(query["agent"].FirstOrDefault()),
+            Models = List(query["model"].FirstOrDefault()),
+            Sources = List(query["source"].FirstOrDefault()),
+            Statuses = List(query["status"].FirstOrDefault()),
+            MinCostUsd = decimal.TryParse(query["minCost"].FirstOrDefault(), System.Globalization.NumberStyles.Any,
+                System.Globalization.CultureInfo.InvariantCulture, out var min) ? min : null,
+            Search = query["q"].FirstOrDefault(),
+            Sort = query["sort"].FirstOrDefault() ?? "time",
+            Descending = !string.Equals(query["dir"].FirstOrDefault(), "asc", StringComparison.OrdinalIgnoreCase),
+            Offset = int.TryParse(query["offset"].FirstOrDefault(), out var o) ? o : 0,
+            Limit = int.TryParse(query["limit"].FirstOrDefault(), out var l) ? l : 50
+        };
+    }
+
+    private static DateTime? ParseDate(string? value)
+        => DateTime.TryParse(value, System.Globalization.CultureInfo.InvariantCulture,
+               System.Globalization.DateTimeStyles.AdjustToUniversal | System.Globalization.DateTimeStyles.AssumeUniversal, out var d)
+            ? DateTime.SpecifyKind(d, DateTimeKind.Utc)
+            : null;
+
+    // ─── Mapping ───
+
+    private static RunRowDto ToDto(RunRow row)
+    {
+        var r = row.Receipt;
+        return new RunRowDto(r.RunId, r.AgentId, r.Model, r.Source, r.TaskId, row.TaskTitle, r.Status,
+            r.StepCount, r.PromptTokens, r.CompletionTokens, r.CachedTokens, r.CostUsd, r.CostIsKnown,
+            r.DurationMs, r.ResultRef, r.OccurredAt);
+    }
+
+    private static RunDetailDto ToDto(RunDetail d) => new(
+        d.RunId,
+        d.Receipt is { } r
+            ? new RunRowDto(r.RunId, r.AgentId, r.Model, r.Source, r.TaskId, d.TaskTitle, r.Status, r.StepCount,
+                r.PromptTokens, r.CompletionTokens, r.CachedTokens, r.CostUsd, r.CostIsKnown, r.DurationMs, r.ResultRef, r.OccurredAt)
+            : null,
+        d.ToolCalls.Select(c => new RunToolCallDto(c.OccurredAt, c.Tool, c.Status.ToString(), c.Arguments, c.Summary, c.DurationMs, c.Source)).ToList(),
+        d.Approvals.Select(c => c.ToDto()).ToList(),
+        d.Transcript is { } t
+            ? new TranscriptDto(t.RunId, t.AgentId, t.Model, t.Source, t.TaskId, t.StartedAt, t.CompletedAt, t.Status,
+                t.Entries, t.SizeChars, t.Truncated)
+            : null,
+        d.SystemPrompt,
+        d.TranscriptState);
+
+    private static PromptHistorySettingsDto SettingsDto(AppHost host)
+    {
+        var instanceDays = PromptHistorySettings.Normalize(host.Instance.PromptHistory.RetentionDays);
+        return new PromptHistorySettingsDto(
+            instanceDays,
+            host.Instance.Agents.Select(a => new AgentRetentionDto(
+                a.AgentId,
+                string.IsNullOrWhiteSpace(a.DisplayName) ? a.AgentId : a.DisplayName,
+                a.PromptHistory.RetentionDays,
+                PromptHistorySettings.Resolve(a.PromptHistory.RetentionDays, instanceDays))).ToList());
+    }
+}
+
+// ─── DTOs (#660) ───
+
+public sealed record RunRowDto(
+    string RunId, string AgentId, string Model, string Source, string? TaskId, string? TaskTitle,
+    string Status, int StepCount, int PromptTokens, int CompletionTokens, int CachedTokens,
+    decimal CostUsd, bool CostIsKnown, long DurationMs, string Result, DateTime OccurredAt);
+
+public sealed record RunTotalsDto(
+    int Runs, long PromptTokens, long CompletionTokens, long CachedTokens,
+    decimal CostUsd, int RunsWithUnknownCost, int NotRun);
+
+public sealed record RunPageDto(IReadOnlyList<RunRowDto> Items, int Total, RunTotalsDto Totals);
+
+public sealed record SeriesPointDto(DateTime BucketStart, string Group, int Runs, long Tokens, decimal CostUsd);
+
+public sealed record UsageEventDto(DateTime At, string Kind, string AgentId, string Text);
+
+public sealed record UsageFacetsDto(
+    IReadOnlyList<string> Agents, IReadOnlyList<string> Models,
+    IReadOnlyList<string> Sources, IReadOnlyList<string> Statuses);
+
+public sealed record RunToolCallDto(
+    DateTime At, string Tool, string Status, string Arguments, string Summary, long DurationMs, string Source);
+
+/// <summary>
+/// Entries go out as recorded. They contain model output and tool results - untrusted
+/// text; the UI inserts them as text, never as HTML.
+/// </summary>
+public sealed record TranscriptDto(
+    string RunId, string AgentId, string Model, string Source, string? TaskId,
+    DateTime StartedAt, DateTime? CompletedAt, string Status,
+    IReadOnlyList<TranscriptEntry> Entries, int SizeChars, bool Truncated);
+
+/// <param name="TranscriptState">recorded, disabled (retention "never"), missing, unavailable.</param>
+public sealed record RunDetailDto(
+    string RunId,
+    RunRowDto? Receipt,
+    IReadOnlyList<RunToolCallDto> ToolCalls,
+    IReadOnlyList<StagedCallDto> Approvals,
+    TranscriptDto? Transcript,
+    string? SystemPrompt,
+    string TranscriptState);
+
+public sealed record TranscriptSummaryDto(
+    string RunId, string AgentId, string Model, string Source, string? TaskId,
+    DateTime StartedAt, DateTime? CompletedAt, string Status,
+    string Prompt, string Response, int SizeChars, bool Truncated);
+
+public sealed record TranscriptPageDto(IReadOnlyList<TranscriptSummaryDto> Items, int Total);
+
+/// <param name="RetentionDays">Own setting of the agent; <c>null</c> = instance default.</param>
+/// <param name="EffectiveRetentionDays">What applies: 0 = never, -1 = forever.</param>
+public sealed record AgentRetentionDto(string AgentId, string DisplayName, int? RetentionDays, int EffectiveRetentionDays);
+
+public sealed record PromptHistorySettingsDto(int DefaultRetentionDays, IReadOnlyList<AgentRetentionDto> Agents);
+
+public sealed record AgentRetentionInputDto(string AgentId, int? RetentionDays);
+
+public sealed record PromptHistorySettingsInputDto(int? DefaultRetentionDays, IReadOnlyList<AgentRetentionInputDto>? Agents);
diff --git a/src/ClawdDotNet.Web/Endpoints/ApiEndpoints.cs b/src/ClawdDotNet.Web/Endpoints/ApiEndpoints.cs
index 9436f3b..92b2fe4 100644
--- a/src/ClawdDotNet.Web/Endpoints/ApiEndpoints.cs
+++ b/src/ClawdDotNet.Web/Endpoints/ApiEndpoints.cs
@@ -29,6 +29,7 @@ internal static class ApiEndpoints
         api.MapTasks();
         api.MapStaging();
         api.MapUsage();
+        api.MapAnalytics();
         api.MapLogs();
 
         app.MapEvents();
diff --git a/tests/ClawdDotNet.App.Tests/Services/AdministrationTests.cs b/tests/ClawdDotNet.App.Tests/Services/AdministrationTests.cs
index 5cca1d1..11b93aa 100644
--- a/tests/ClawdDotNet.App.Tests/Services/AdministrationTests.cs
+++ b/tests/ClawdDotNet.App.Tests/Services/AdministrationTests.cs
@@ -198,6 +198,25 @@ public sealed class AgentAdministrationTests
         host.Host.AgentAdmin.Find("scout")!.Tools["Database"].ShouldContainKey("erlaubt");
     }
 
+    // ─── #660: prompt history retention ───
+
+    [Fact]
+    public void Prompt_history_retention_is_stored_per_agent_and_for_the_instance()
+    {
+        using var host = new TestHost();
+        host.Host.AgentAdmin.Add(new NewAgent("tresor", "Tresor", "modell"));
+
+        host.Host.AgentAdmin.SetPromptHistoryRetention("tresor", 0).Ok.ShouldBeTrue();
+        host.Host.AgentAdmin.SetDefaultPromptHistoryRetention(30).Ok.ShouldBeTrue();
+
+        var reloaded = host.Host.Directories.LoadInstanceConfig(host.Host.InstancePath);
+        reloaded.PromptHistory.RetentionDays.ShouldBe(30);
+        reloaded.Agents.Single(a => a.AgentId == "tresor").PromptHistory.RetentionDays.ShouldBe(0);
+
+        host.Host.AgentAdmin.SetPromptHistoryRetention("tresor", null).Ok.ShouldBeTrue();
+        host.Host.AgentAdmin.Find("tresor")!.PromptHistory.RetentionDays.ShouldBeNull("back to the instance default");
+    }
+
     [Fact]
     public void Rechte_nur_fuer_zugewiesene_Werkzeuge()
     {
diff --git a/tests/ClawdDotNet.Core.Tests/Analytics/UsageAnalyticsTests.cs b/tests/ClawdDotNet.Core.Tests/Analytics/UsageAnalyticsTests.cs
new file mode 100644
index 0000000..c8bf04d
--- /dev/null
+++ b/tests/ClawdDotNet.Core.Tests/Analytics/UsageAnalyticsTests.cs
@@ -0,0 +1,143 @@
+using ClawdDotNet.Core.Analytics;
+using ClawdDotNet.Core.Audit;
+using ClawdDotNet.Core.Tests.Infrastructure;
+using Shouldly;
+
+namespace ClawdDotNet.Core.Tests.Analytics;
+
+/// <summary>
+/// Usage analysis (#660): filter, sort, page and bucket run receipts. Totals cover the whole
+/// filter, not only the page; runs refused before any model call are counted separately.
+/// </summary>
+public sealed class UsageAnalyticsTests
+{
+    private static readonly DateTime Day = new(2026, 9, 19, 0, 0, 0, DateTimeKind.Utc);
+
+    private static RunReceipt Receipt(string agent, int hour, decimal cost, string model = "gemini", string status = "Completed",
+        string source = "task", string? task = null, int prompt = 1000, string result = "ERGEBNIS: ok")
+        => new()
+        {
+            RunId = Guid.NewGuid().ToString("N"),
+            AgentId = agent,
+            Model = model,
+            Source = source,
+            TaskId = task,
+            Status = status,
+            StepCount = 3,
+            PromptTokens = prompt,
+            CompletionTokens = 100,
+            CostUsd = cost,
+            CostIsKnown = cost > 0,
+            ResultRef = result,
+            OccurredAt = Day.AddHours(hour)
+        };
+
+    private static UsageAnalytics Analytics(params RunReceipt[] receipts)
+    {
+        var audit = new InMemoryAuditRepository();
+        foreach (var r in receipts) audit.Receipts.Enqueue(r);
+        return new UsageAnalytics(audit, (id, _) => Task.FromResult<string?>(id == "t-1" ? "Wetter abrufen" : null));
+    }
+
+    private static RunQuery All => new() { FromUtc = Day, ToUtc = Day.AddDays(1) };
+
+    [Fact]
+    public async Task Totals_cover_the_whole_filter_not_only_the_page()
+    {
+        var analytics = Analytics(
+            Receipt("wetter", 1, 0.01m), Receipt("wetter", 2, 0.02m), Receipt("kurse", 3, 0.04m),
+            Receipt("kurse", 4, 0m, status: "BudgetExceeded", prompt: 0));
+
+        var page = await analytics.QueryRunsAsync(All with { Limit = 1 }, default);
+
+        page.Items.Count.ShouldBe(1);
+        page.Total.ShouldBe(4);
+        page.Totals.CostUsd.ShouldBe(0.07m);
+        page.Totals.NotRun.ShouldBe(1);
+        page.Totals.RunsWithUnknownCost.ShouldBe(0, "a refused run has no cost to know");
+    }
+
+    [Fact]
+    public async Task Filters_combine()
+    {
+        var analytics = Analytics(
+            Receipt("wetter", 1, 0.01m, model: "haiku"), Receipt("wetter", 2, 0.02m, model: "gemini"),
+            Receipt("kurse", 3, 0.04m, model: "gemini"));
+
+        var page = await analytics.QueryRunsAsync(All with { Agents = ["wetter"], Models = ["gemini"] }, default);
+
+        page.Total.ShouldBe(1);
+        page.Items.Single().Receipt.CostUsd.ShouldBe(0.02m);
+        (await analytics.QueryRunsAsync(All with { MinCostUsd = 0.015m }, default)).Total.ShouldBe(2);
+    }
+
+    [Fact]
+    public async Task The_search_covers_task_title_and_result()
+    {
+        var analytics = Analytics(
+            Receipt("wetter", 1, 0.01m, task: "t-1"),
+            Receipt("kurse", 2, 0.01m, result: "ERGEBNIS: NVDA bei 120"));
+
+        (await analytics.QueryRunsAsync(All with { Search = "wetter abrufen" }, default)).Items.Single().TaskTitle.ShouldBe("Wetter abrufen");
+        (await analytics.QueryRunsAsync(All with { Search = "nvda" }, default)).Items.Single().Receipt.AgentId.ShouldBe("kurse");
+    }
+
+    [Theory]
+    [InlineData("cost", true, 0.04)]
+    [InlineData("cost", false, 0.01)]
+    [InlineData("time", true, 0.02)]
+    public async Task Every_column_sorts(string sort, bool descending, double firstCost)
+    {
+        var analytics = Analytics(Receipt("a", 1, 0.01m), Receipt("b", 5, 0.02m), Receipt("c", 3, 0.04m));
+
+        var page = await analytics.QueryRunsAsync(All with { Sort = sort, Descending = descending }, default);
+
+        page.Items[0].Receipt.CostUsd.ShouldBe((decimal)firstCost);
+    }
+
+    [Fact]
+    public async Task Series_stack_per_bucket_and_group()
+    {
+        var analytics = Analytics(Receipt("wetter", 1, 0.01m), Receipt("wetter", 1, 0.02m), Receipt("kurse", 1, 0.04m), Receipt("wetter", 5, 0.1m));
+
+        var points = await analytics.SeriesAsync(All, "hour", "agent", TimeSpan.Zero, default);
+
+        points.Count.ShouldBe(3);
+        points.Single(p => p.Group == "wetter" && p.BucketStart == Day.AddHours(1)).CostUsd.ShouldBe(0.03m);
+        points.Single(p => p.Group == "wetter" && p.BucketStart == Day.AddHours(1)).Runs.ShouldBe(2);
+    }
+
+    [Fact]
+    public void A_day_is_the_viewers_day()
+    {
+        // 23:30 UTC is already the next day in Berlin (UTC+2).
+        var bucket = UsageAnalytics.BucketStart(Day.AddHours(23.5), "day", TimeSpan.FromHours(2));
+        bucket.ShouldBe(Day.AddDays(1).AddHours(-2), "local midnight of 20.09 expressed in UTC");
+    }
+
+    [Fact]
+    public async Task Budget_denials_and_model_changes_become_events()
+    {
+        var analytics = Analytics(
+            Receipt("wetter", 1, 0.01m, model: "haiku"),
+            Receipt("wetter", 2, 0.01m, model: "gemini"),
+            Receipt("wetter", 3, 0m, status: "BudgetExceeded", model: "gemini"),
+            Receipt("wetter", 3, 0m, status: "BudgetExceeded", model: "gemini"));
+
+        var events = await analytics.EventsAsync(Day, Day.AddDays(1), default);
+
+        events.Single(e => e.Kind == "model_changed").Text.ShouldBe("haiku → gemini");
+        events.Single(e => e.Kind == "budget_exceeded").Text.ShouldContain("2 run(s)");
+    }
+
+    [Fact]
+    public async Task Facets_list_what_occurs()
+    {
+        var analytics = Analytics(Receipt("wetter", 1, 0.01m, source: "task"), Receipt("kurse", 1, 0.01m, source: "webui", model: "haiku"));
+
+        var facets = await analytics.FacetsAsync(Day, Day.AddDays(1), default);
+
+        facets.Agents.ShouldBe(["kurse", "wetter"]);
+        facets.Sources.ShouldBe(["task", "webui"]);
+    }
+}
diff --git a/tests/ClawdDotNet.Core.Tests/Infrastructure/EngineFixture.cs b/tests/ClawdDotNet.Core.Tests/Infrastructure/EngineFixture.cs
index de96218..cbceec1 100644
--- a/tests/ClawdDotNet.Core.Tests/Infrastructure/EngineFixture.cs
+++ b/tests/ClawdDotNet.Core.Tests/Infrastructure/EngineFixture.cs
@@ -26,7 +26,7 @@ internal sealed class EngineFixture
 
     public EngineFixture(
         IAuditRepository? audit = null, StagingGate? staging = null, TimeProvider? clock = null,
-        IUsageRepository? usage = null)
+        IUsageRepository? usage = null, Core.Transcripts.IRunTranscriptStore? transcripts = null)
     {
         Engine = new AgentEngine(
             Client,
@@ -37,7 +37,10 @@ internal sealed class EngineFixture
             usageRepository: usage,
             auditRepository: audit,
             stagingGate: staging,
-            clock: clock);
+            clock: clock)
+        {
+            TranscriptStore = transcripts
+        };
 
         // Kein Agent-Verzeichnis → keine Persistenz auf die Platte während der Tests.
         Engine.SetAgentConfigProvider(() => _agents, "test-instance", _ => null);
diff --git a/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryAuditRepository.cs b/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryAuditRepository.cs
index 84e60a9..67f25b9 100644
--- a/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryAuditRepository.cs
+++ b/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryAuditRepository.cs
@@ -36,6 +36,11 @@ internal sealed class InMemoryAuditRepository : IAuditRepository
     public Task<IReadOnlyList<RunReceipt>> ListReceiptsForTaskAsync(string taskId, CancellationToken ct)
         => Task.FromResult<IReadOnlyList<RunReceipt>>(Receipts.Where(r => r.TaskId == taskId).ToList());
 
+    public Task<IReadOnlyList<RunReceipt>> ListReceiptsAsync(DateTime fromUtc, DateTime toUtc, int limit, CancellationToken ct)
+        => Task.FromResult<IReadOnlyList<RunReceipt>>(Receipts
+            .Where(r => r.OccurredAt >= fromUtc && r.OccurredAt < toUtc)
+            .OrderBy(r => r.OccurredAt).Take(limit).ToList());
+
     public Task<int> CountAsync(CancellationToken ct) => Task.FromResult(Entries.Count);
 
     /// <summary>Spiegelt die SQL-Regel: Started ohne späteren Abschluss derselben CallId.</summary>
diff --git a/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryStagingRepository.cs b/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryStagingRepository.cs
index 41c515d..19cd1cd 100644
--- a/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryStagingRepository.cs
+++ b/tests/ClawdDotNet.Core.Tests/Infrastructure/InMemoryStagingRepository.cs
@@ -20,6 +20,9 @@ internal sealed class InMemoryStagingRepository : IStagingRepository
     public Task<StagedCall?> GetAsync(long id, CancellationToken ct)
         => Task.FromResult(_calls.GetValueOrDefault(id));
 
+    public Task<IReadOnlyList<StagedCall>> ListForRunAsync(string runId, CancellationToken ct)
+        => Task.FromResult<IReadOnlyList<StagedCall>>(_calls.Values.Where(c => c.RunId == runId).OrderBy(c => c.Id).ToList());
+
     public Task<int> CountExecutedAsync(string agentId, string tool, string? action, DateTime since, CancellationToken ct)
         => Task.FromResult(_calls.Values.Count(c =>
             c.Status == StagingStatus.Executed && c.AgentId == agentId && c.Tool == tool
diff --git a/tests/ClawdDotNet.Core.Tests/Transcripts/PromptHistoryTests.cs b/tests/ClawdDotNet.Core.Tests/Transcripts/PromptHistoryTests.cs
new file mode 100644
index 0000000..5b66999
--- /dev/null
+++ b/tests/ClawdDotNet.Core.Tests/Transcripts/PromptHistoryTests.cs
@@ -0,0 +1,244 @@
+using ClawdDotNet.Core.Api.Models;
+using ClawdDotNet.Core.Storage;
+using ClawdDotNet.Core.Tests.Infrastructure;
+using ClawdDotNet.Core.Transcripts;
+using Shouldly;
+
+namespace ClawdDotNet.Core.Tests.Transcripts;
+
+/// <summary>
+/// Prompt history (#660): prompt and response of every run are recorded, bounded in size,
+/// scrubbed of recognisable secrets, searchable, and deleted once the retention of the
+/// agent - or the instance default - says so.
+/// </summary>
+public sealed class PromptHistoryTests : IDisposable
+{
+    private readonly string _directory;
+    private readonly SqliteStorage _storage;
+    private readonly SqliteRunTranscriptStore _store;
+
+    public PromptHistoryTests()
+    {
+        _directory = Path.Combine(Path.GetTempPath(), "clawd-tests", Guid.NewGuid().ToString("N"));
+        _storage = new SqliteStorage(Path.Combine(_directory, "state.db"));
+        _store = new SqliteRunTranscriptStore(_storage);
+    }
+
+    public void Dispose()
+    {
+        Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
+        try { Directory.Delete(_directory, recursive: true); }
+        catch { /* cleanup is best effort */ }
+    }
+
+    private static ToolCall Call(string id, string name, string args)
+        => new() { Id = id, Function = new ToolCallFunction { Name = name, Arguments = args } };
+
+    // ─── Retention settings ───
+
+    [Theory]
+    [InlineData(null, 14, 14)]
+    [InlineData(0, 14, 0)]
+    [InlineData(-1, 14, -1)]
+    [InlineData(365, 14, 365)]
+    [InlineData(null, 0, 0)]
+    [InlineData(-7, 14, -1)]
+    public void The_agent_setting_overrides_the_instance_default(int? agent, int instance, int expected)
+        => PromptHistorySettings.Resolve(agent, instance).ShouldBe(expected);
+
+    // ─── Recorder ───
+
+    [Fact]
+    public void The_recorder_keeps_task_steps_tool_results_and_usage()
+    {
+        var recorder = new RunTranscriptRecorder();
+        recorder.Begin("You are a test.", "Fetch the weather.");
+        recorder.ModelStep(new ChatMessage { Role = "assistant", Content = "Let me look.", ToolCalls = [Call("c1", "WebFetch", "{\"url\":\"x\"}")] },
+            new Usage { PromptTokens = 120, CompletionTokens = 30, Cost = 0.0004m }, "tool_calls");
+        recorder.ToolResults([Call("c1", "WebFetch", "{}")], ["18 °C"]);
+        recorder.ModelStep(new ChatMessage { Role = "assistant", Content = "ERGEBNIS: ok - 18 °C" }, null, "stop");
+
+        var t = recorder.Build("run-1", "wetter", "m", "task", "t-1", "Completed");
+
+        t.Entries.Select(e => e.Kind).ShouldBe(["user", "assistant", "tool_result", "assistant"]);
+        t.Entries[1].ToolCalls!.Single().Name.ShouldBe("WebFetch");
+        t.Entries[1].PromptTokens.ShouldBe(120);
+        t.Entries[1].CostUsd.ShouldBe(0.0004m);
+        t.Entries[2].ToolName.ShouldBe("WebFetch");
+        t.SystemPromptHash.ShouldNotBeNull();
+        recorder.SystemPrompt.ShouldBe("You are a test.");
+    }
+
+    [Fact]
+    public void Long_tool_results_keep_start_and_end()
+    {
+        var recorder = new RunTranscriptRecorder();
+        var text = "START" + new string('x', 20_000) + "END";
+        recorder.ToolResults([Call("c", "FileRW", "{}")], [text]);
+
+        var entry = recorder.Build("r", "a", "m", "task", null, "Completed").Entries.Single();
+        entry.Clipped.ShouldBeTrue();
+        entry.Text!.Length.ShouldBeLessThan(RunTranscriptRecorder.MaxToolResultChars + 100);
+        entry.Text.ShouldStartWith("START");
+        entry.Text.ShouldEndWith("END");
+    }
+
+    [Fact]
+    public void A_runaway_run_stops_storing_text_but_keeps_the_heads()
+    {
+        var recorder = new RunTranscriptRecorder();
+        for (var i = 0; i < 100; i++)
+            recorder.ToolResults([Call($"c{i}", "WebFetch", "{}")], [new string('y', 4_000)]);
+
+        var t = recorder.Build("r", "a", "m", "task", null, "LoopLimitExceeded");
+        t.Truncated.ShouldBeTrue();
+        t.SizeChars.ShouldBeLessThanOrEqualTo(RunTranscriptRecorder.MaxTotalChars);
+        t.Entries.Count.ShouldBe(100, "every call is still listed");
+        t.Entries.Last().Text.ShouldBeNull();
+    }
+
+    [Theory]
+    [InlineData("key sk-or-v1-0123456789abcdef0123456789abcdef here")]
+    [InlineData("Server=db;Password=geheim123;Database=x")]
+    [InlineData("Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.abcdefghijk")]
+    [InlineData("Lizenz ABCDE-12345-FGHIJ-67890-KLMNO")]
+    public void Recognisable_secrets_are_scrubbed(string text)
+    {
+        var recorder = new RunTranscriptRecorder();
+        recorder.Begin(null, text);
+
+        var stored = recorder.Build("r", "a", "m", "task", null, "Completed").Entries.Single().Text!;
+        stored.ShouldContain(SecretScrubber.Mask);
+        stored.ShouldNotContain("geheim123");
+        stored.ShouldNotContain("0123456789abcdef0123456789abcdef");
+    }
+
+    [Fact]
+    public void A_disabled_recorder_keeps_nothing()
+    {
+        var recorder = RunTranscriptRecorder.Disabled;
+        recorder.Begin("s", "u");
+        recorder.Enabled.ShouldBeFalse();
+    }
+
+    // ─── Store ───
+
+    private static RunTranscript Transcript(string runId, string agent, DateTime started, string text = "Hallo Grüße")
+        => new()
+        {
+            RunId = runId,
+            AgentId = agent,
+            Model = "m",
+            Source = "task",
+            StartedAt = started,
+            CompletedAt = started.AddSeconds(5),
+            Status = "Completed",
+            Entries =
+            [
+                new TranscriptEntry { Kind = TranscriptEntryKind.User, At = started, Text = text },
+                new TranscriptEntry { Kind = TranscriptEntryKind.Assistant, At = started, Text = "ERGEBNIS: ok" }
+            ],
+            SizeChars = text.Length + 12
+        };
+
+    [Fact]
+    public async Task A_transcript_is_stored_and_read_back_with_its_system_prompt()
+    {
+        var t = Transcript("run-1", "wetter", DateTime.UtcNow) with { SystemPromptHash = RunTranscriptRecorder.Hash("sys") };
+        await _store.SaveAsync(t, "sys", default);
+
+        var back = (await _store.GetAsync("run-1", default)).ShouldNotBeNull();
+        back.Entries.Count.ShouldBe(2);
+        back.Entries[0].Text.ShouldBe("Hallo Grüße");
+        (await _store.GetSystemPromptAsync(t.SystemPromptHash!, default)).ShouldBe("sys");
+    }
+
+    [Fact]
+    public async Task The_search_finds_text_with_umlauts_and_filters_by_agent()
+    {
+        await _store.SaveAsync(Transcript("a", "wetter", DateTime.UtcNow, "Unwetterwarnung für Berlin"), null, default);
+        await _store.SaveAsync(Transcript("b", "kurse", DateTime.UtcNow, "Kurs von NVDA"), null, default);
+
+        var (items, total) = await _store.ListAsync(new TranscriptQuery { Search = "für Berlin" }, default);
+        total.ShouldBe(1);
+        items.Single().RunId.ShouldBe("a");
+        items.Single().Prompt.ShouldBe("Unwetterwarnung für Berlin");
+        items.Single().Response.ShouldBe("ERGEBNIS: ok");
+
+        (await _store.ListAsync(new TranscriptQuery { AgentId = "kurse" }, default)).Total.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task Purge_follows_the_retention_of_each_agent()
+    {
+        var now = DateTime.UtcNow;
+        await _store.SaveAsync(Transcript("old-default", "a", now.AddDays(-20)), null, default);
+        await _store.SaveAsync(Transcript("new-default", "a", now.AddDays(-2)), null, default);
+        await _store.SaveAsync(Transcript("old-forever", "debug", now.AddDays(-400)), null, default);
+        await _store.SaveAsync(Transcript("fresh-never", "secret", now), null, default);
+
+        var deleted = await _store.PurgeAsync(agent => agent switch
+        {
+            "debug" => PromptHistorySettings.Forever,
+            "secret" => PromptHistorySettings.Never,
+            _ => 14
+        }, now, default);
+
+        deleted.ShouldBe(2);
+        (await _store.GetAsync("old-default", default)).ShouldBeNull();
+        (await _store.GetAsync("new-default", default)).ShouldNotBeNull();
+        (await _store.GetAsync("old-forever", default)).ShouldNotBeNull();
+        (await _store.GetAsync("fresh-never", default)).ShouldBeNull("never also removes what was recorded before");
+    }
+
+    // ─── Engine ───
+
+    [Fact]
+    public async Task Every_run_leaves_its_transcript()
+    {
+        var fixture = new EngineFixture(transcripts: _store).WithTool(FakeTool.Returning("18 °C", "Wetter"));
+        var agent = fixture.AddAgent("wetterdienst", "Wetter");
+        fixture.Client.RespondsWithToolCall("Wetter", "{\"ort\":\"Berlin\"}").RespondsWithText("Es sind 18 °C.");
+
+        await fixture.Engine.RunAsync(agent, "Wie ist das Wetter?", "test-instance", default);
+
+        var (items, _) = await _store.ListAsync(new TranscriptQuery(), default);
+        var t = (await _store.GetAsync(items.Single().RunId, default)).ShouldNotBeNull();
+        t.AgentId.ShouldBe("wetterdienst");
+        t.Entries.Select(e => e.Kind).ShouldBe(["user", "assistant", "tool_result", "assistant"]);
+        t.Entries[0].Text.ShouldContain("Wie ist das Wetter?");
+        t.Entries[2].Text.ShouldNotBeNull().ShouldContain("18 °C", Case.Sensitive, "stored as the model saw it, frame included");
+        t.Entries[3].Text.ShouldBe("Es sind 18 °C.");
+        (await _store.GetSystemPromptAsync(t.SystemPromptHash!, default)).ShouldNotBeNull().ShouldContain("wetterdienst");
+    }
+
+    [Fact]
+    public async Task An_agent_set_to_never_is_not_recorded()
+    {
+        var fixture = new EngineFixture(transcripts: _store);
+        var agent = fixture.AddAgent("tresor");
+        agent.PromptHistory.RetentionDays = PromptHistorySettings.Never;
+        fixture.Client.RespondsWithText("geheim");
+
+        await fixture.Engine.RunAsync(agent, "Passwort?", "test-instance", default);
+
+        (await _store.ListAsync(new TranscriptQuery(), default)).Total.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task Chats_are_recorded_per_run_not_as_the_whole_history()
+    {
+        var fixture = new EngineFixture(transcripts: _store);
+        var agent = fixture.AddAgent("assistent");
+        fixture.Client.RespondsWithText("Erste Antwort").RespondsWithText("Zweite Antwort");
+
+        await fixture.Engine.ChatAsync(agent, "Erste Frage", "test-instance", default);
+        await fixture.Engine.ChatAsync(agent, "Zweite Frage", "test-instance", default);
+
+        var (items, _) = await _store.ListAsync(new TranscriptQuery(), default);
+        items.Count.ShouldBe(2);
+        var second = (await _store.GetAsync(items.First().RunId, default)).ShouldNotBeNull();
+        second.Entries.Count(e => e.Kind == TranscriptEntryKind.User).ShouldBe(1);
+        second.Entries[0].Text.ShouldContain("Zweite Frage");
+    }
+}