diff --git a/Controllers/WorkflowsController.cs b/Controllers/WorkflowsController.cs
index f372a76..d2a3b4c 100644
--- a/Controllers/WorkflowsController.cs
+++ b/Controllers/WorkflowsController.cs
@@ -86,8 +86,9 @@ public class WorkflowsController : ControllerBase
             })
             .ToListAsync(ct);
 
-        // Latest run per workflow (status + finish time) so the list can surface
-        // the last execution in one column without a round-trip per row.
+        // Latest run per workflow (status, time + duration) and total run count so
+        // the list can surface the last execution and execution count without a
+        // round-trip per row.
         var ids = workflows.Select(w => w.Id).ToList();
         var lastRuns = await _db.WorkflowRuns
             .Where(r => r.TenantId == TenantId && ids.Contains(r.WorkflowId))
@@ -95,6 +96,7 @@ public class WorkflowsController : ControllerBase
             .Select(g => new
             {
                 WorkflowId = g.Key,
+                RunCount = g.Count(),
                 Status = g
                     .OrderByDescending(r => r.StartedAt ?? r.FinishedAt ?? DateTime.MinValue)
                     .ThenByDescending(r => r.Id)
@@ -137,8 +139,12 @@ public class WorkflowsController : ControllerBase
                 w.Version,
                 w.taskCount,
                 w.upToDate,
+                runCount = last?.RunCount ?? 0,
                 lastRunStatus = last?.Status,
                 lastRunAt = last?.FinishedAt ?? last?.StartedAt,
+                lastRunDuration = last is { StartedAt: DateTime s, FinishedAt: DateTime f }
+                    ? (f - s).TotalSeconds
+                    : (double?)null,
                 lastRunError = last?.Error,
             };
         });
@@ -429,4 +435,48 @@ public class WorkflowsController : ControllerBase
             return StatusCode(StatusCodes.Status500InternalServerError, new { error = ex.Message });
         }
     }
+
+    /// <summary>
+    /// Clears the run history for one workflow: deletes every run (and, via the
+    /// FK cascade, its task runs). The workflow definition, its tasks and its
+    /// trigger are untouched — only the history is wiped. Returns the number of
+    /// runs removed.
+    /// </summary>
+    [HttpDelete("{id:guid}/runs")]
+    [RequireScope("manage")]
+    public async Task<IActionResult> ClearRuns(Guid id, CancellationToken ct)
+    {
+        var owned = await _db.Workflows.AnyAsync(w => w.Id == id && w.TenantId == TenantId, ct);
+        if (!owned)
+            return NotFound(new { error = "Workflow not found." });
+
+        var runIds = await _db.WorkflowRuns
+            .Where(r => r.WorkflowId == id && r.TenantId == TenantId)
+            .Select(r => r.Id)
+            .ToListAsync(ct);
+
+        if (runIds.Count > 0)
+        {
+            // Remove task runs explicitly first so EF does not depend on the DB
+            // cascade for the (already configured) FK; then remove the runs.
+            var taskRuns = await _db.TaskRuns
+                .Where(t => runIds.Contains(t.RunId))
+                .ToListAsync(ct);
+            _db.TaskRuns.RemoveRange(taskRuns);
+
+            var runs = await _db.WorkflowRuns
+                .Where(r => runIds.Contains(r.Id))
+                .ToListAsync(ct);
+            _db.WorkflowRuns.RemoveRange(runs);
+
+            await _db.SaveChangesAsync(ct);
+        }
+
+        _logger.LogInformation(
+            "Cleared {Count} run(s) for workflow {WorkflowId} (tenant {TenantId})",
+            runIds.Count, id, TenantId);
+        return Ok(new ClearRunsResponse(runIds.Count));
+    }
+
+    public sealed record ClearRunsResponse(int Cleared);
 }
diff --git a/w4c-workflows-api.Tests/WorkflowsControllerListAndClearTests.cs b/w4c-workflows-api.Tests/WorkflowsControllerListAndClearTests.cs
new file mode 100644
index 0000000..b4ab049
--- /dev/null
+++ b/w4c-workflows-api.Tests/WorkflowsControllerListAndClearTests.cs
@@ -0,0 +1,155 @@
+using System.Text.Json;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging.Abstractions;
+using w4c_workflows.Controllers;
+using w4c_workflows.Data;
+using w4c_workflows.Models;
+using w4c_workflows.Services;
+using w4c_workflows.Services.Runs;
+using Xunit;
+
+using ClearRunsResponse = w4c_workflows.Controllers.WorkflowsController.ClearRunsResponse;
+
+namespace w4c_workflows.Tests;
+
+[Collection("WorkflowsPostgres")]
+public class WorkflowsControllerListAndClearTests
+{
+    private const string YamlContent = "name: linear\nmode: function\nlanguage: shell\n";
+
+    private sealed class FakeWorkflowSource : IWorkflowSource
+    {
+        public Task<IReadOnlyList<WorkflowFile>> ListAsync(CancellationToken ct)
+            => Task.FromResult<IReadOnlyList<WorkflowFile>>(Array.Empty<WorkflowFile>());
+
+        public Task<string> ReadAsync(string path, CancellationToken ct)
+            => Task.FromResult(YamlContent);
+
+        public WorkflowSourceState GetState() => new(null, false);
+    }
+
+    private readonly WorkflowsPostgresFixture _fixture;
+
+    public WorkflowsControllerListAndClearTests(WorkflowsPostgresFixture fixture)
+    {
+        _fixture = fixture;
+    }
+
+    private static WorkflowsController Controller(WorkflowsDbContext db, string tenantId)
+    {
+        var sync = new WorkflowSyncService(
+            db,
+            new WorkflowCompiler(new WorkflowValidator(new LanguageRegistry())),
+            new FakeWorkflowSource(),
+            NullLogger<WorkflowSyncService>.Instance);
+
+        var controller = new WorkflowsController(
+            db,
+            sync,
+            new FakeWorkflowSource(),
+            new MermaidGeneratorService(),
+            new WorkflowHtmlRenderer(NullLogger<WorkflowHtmlRenderer>.Instance),
+            new RenderTokenService(new ConfigurationBuilder().Build(), NullLogger<RenderTokenService>.Instance),
+            new RunLauncher(db, NullLogger<RunLauncher>.Instance),
+            new DurableStateStore(db),
+            NullLogger<WorkflowsController>.Instance)
+        {
+            ControllerContext = new ControllerContext { HttpContext = new DefaultHttpContext() },
+        };
+        controller.HttpContext.Items["TenantId"] = tenantId;
+        return controller;
+    }
+
+    private static string Tenant() => "t" + Guid.NewGuid().ToString("N")[..12];
+
+    [Fact]
+    public async Task List_returns_run_count_and_last_run_duration()
+    {
+        var tenantId = Tenant();
+        await using var db = _fixture.CreateContext();
+        var workflow = WorkflowDataHelpers.CompileAndSave(db, tenantId, WorkflowDataHelpers.LinearYaml);
+
+        // Two finished runs + one in-flight run (started longest ago so the latest
+        // run by time is the finished one) for the same workflow.
+        WorkflowDataHelpers.AddRun(db, workflow, RunStatus.Succeeded,
+            startedAt: DateTime.UtcNow.AddMinutes(-5), finishedAt: DateTime.UtcNow.AddMinutes(-4));
+        WorkflowDataHelpers.AddRun(db, workflow, RunStatus.Failed,
+            startedAt: DateTime.UtcNow.AddMinutes(-2), finishedAt: DateTime.UtcNow.AddMinutes(-1), error: "boom");
+        WorkflowDataHelpers.AddRun(db, workflow, RunStatus.Running, startedAt: DateTime.UtcNow.AddMinutes(-10));
+
+        // A workflow with no runs must default to 0 / null, not throw.
+        var empty = WorkflowDataHelpers.CompileAndSave(db, tenantId, WorkflowDataHelpers.DurableYaml, "workflows/b.yaml");
+
+        var result = Assert.IsType<OkObjectResult>(await Controller(db, tenantId).List(default));
+        var json = JsonSerializer.Serialize(result.Value, new JsonSerializerOptions(JsonSerializerDefaults.Web));
+        using var doc = JsonDocument.Parse(json);
+        var root = doc.RootElement;
+
+        var first = root.GetProperty("workflows").EnumerateArray()
+            .Single(w => w.GetProperty("id").GetGuid() == workflow.Id);
+        // The latest run is the failed one (started -2m), so duration = 60s.
+        Assert.Equal(3, first.GetProperty("runCount").GetInt32());
+        Assert.Equal(RunStatus.Failed, first.GetProperty("lastRunStatus").GetString());
+        Assert.Equal(60, first.GetProperty("lastRunDuration").GetDouble(), 1);
+
+        var second = root.GetProperty("workflows").EnumerateArray()
+            .Single(w => w.GetProperty("id").GetGuid() == empty.Id);
+        Assert.Equal(0, second.GetProperty("runCount").GetInt32());
+        Assert.Equal(JsonValueKind.Null, second.GetProperty("lastRunDuration").ValueKind);
+        Assert.Equal(JsonValueKind.Null, second.GetProperty("lastRunStatus").ValueKind);
+    }
+
+    [Fact]
+    public async Task ClearRuns_deletes_runs_and_task_runs_for_the_workflow()
+    {
+        var tenantId = Tenant();
+        await using var db = _fixture.CreateContext();
+        var workflow = WorkflowDataHelpers.CompileAndSave(db, tenantId, WorkflowDataHelpers.LinearYaml);
+        var done = WorkflowDataHelpers.AddRun(db, workflow, RunStatus.Succeeded,
+            DateTime.UtcNow.AddMinutes(-5), DateTime.UtcNow.AddMinutes(-4));
+        var failed = WorkflowDataHelpers.AddRun(db, workflow, RunStatus.Failed,
+            DateTime.UtcNow.AddMinutes(-2), DateTime.UtcNow.AddMinutes(-1), error: "boom");
+
+        var root = WorkflowDataHelpers.TaskByKey(workflow, "root");
+        db.TaskRuns.AddRange(
+            new TaskRun { Id = Guid.NewGuid(), RunId = done.Id, TaskId = root.Id, Attempt = 1, Status = TaskRunStatus.Succeeded },
+            new TaskRun { Id = Guid.NewGuid(), RunId = failed.Id, TaskId = root.Id, Attempt = 1, Status = TaskRunStatus.Failed });
+        db.SaveChanges();
+
+        var result = Assert.IsType<OkObjectResult>(await Controller(db, tenantId).ClearRuns(workflow.Id, default));
+        var body = Assert.IsType<ClearRunsResponse>(result.Value);
+        Assert.Equal(2, body.Cleared);
+
+        Assert.Empty(await db.WorkflowRuns.Where(r => r.WorkflowId == workflow.Id).ToListAsync());
+        Assert.Empty(await db.TaskRuns.Where(t => t.RunId == done.Id || t.RunId == failed.Id).ToListAsync());
+        // The workflow definition itself is untouched.
+        Assert.True(await db.Workflows.AnyAsync(w => w.Id == workflow.Id));
+    }
+
+    [Fact]
+    public async Task ClearRuns_404s_for_foreign_workflow()
+    {
+        var tenantId = Tenant();
+        await using var db = _fixture.CreateContext();
+        var other = Tenant();
+        var workflow = WorkflowDataHelpers.CompileAndSave(db, other, WorkflowDataHelpers.LinearYaml);
+
+        var result = await Controller(db, tenantId).ClearRuns(workflow.Id, default);
+        Assert.IsType<NotFoundObjectResult>(result);
+    }
+
+    [Fact]
+    public async Task ClearRuns_is_idempotent_when_no_runs_exist()
+    {
+        var tenantId = Tenant();
+        await using var db = _fixture.CreateContext();
+        var workflow = WorkflowDataHelpers.CompileAndSave(db, tenantId, WorkflowDataHelpers.LinearYaml);
+
+        var result = Assert.IsType<OkObjectResult>(await Controller(db, tenantId).ClearRuns(workflow.Id, default));
+        var body = Assert.IsType<ClearRunsResponse>(result.Value);
+        Assert.Equal(0, body.Cleared);
+    }
+}