diff --git a/contrib/Makefile b/contrib/Makefile
index 79145668f..4e4ef4df6 100644
--- a/contrib/Makefile
+++ b/contrib/Makefile
@@ -95,6 +95,15 @@ showConfig:
 	@echo CONFIGURATION: $(CONFIGURATION)
 	@echo BASEAPPDIR: $(BASEAPPDIR)
 
+showApiLogs:
+	@sudo journalctl -u yavscApi.service -S "2 min ago" | tee yavscApi.log
+
+showOrgLogs:
+	@sudo journalctl -u yavscOrg.service -S "2 min ago" | tee yavscOrg.log
+
+showBlogsLogs:
+	@sudo journalctl -u yavscBlogs.service -S "2 min ago" | tee yavscBlogs.log
+
 clean:
 	@rm -rf generated
 
diff --git a/src/PostIt/PostIt.Tests/EstimateEditionPageViewModelTests.cs b/src/PostIt/PostIt.Tests/EstimateEditionPageViewModelTests.cs
new file mode 100644
index 000000000..db70e25fa
--- /dev/null
+++ b/src/PostIt/PostIt.Tests/EstimateEditionPageViewModelTests.cs
@@ -0,0 +1,270 @@
+using System.Net.Http;
+using PostIt.ViewModels;
+using Yavsc;
+using Yavsc.Api.Client;
+
+namespace PostIt.Tests;
+
+public class EstimateEditionPageViewModelTests
+{
+    private static BillingQuerySummaryDto SampleQuery() => new()
+    {
+        Id = 42,
+        BillingCode = "Brush",
+        ActivityCode = "hair",
+        PerformerId = "perf-1",
+        ClientId = "cli-1",
+        Status = QueryStatus.InProgress,
+        Description = "Coupe simple",
+        EventDate = new DateTime(2026, 9, 12, 10, 0, 0, DateTimeKind.Utc),
+    };
+
+    private static EstimateEditionPageViewModel CreateViewModel(StubEstimateApi api, BillingQuerySummaryDto? query = null)
+    {
+        var client = new EstimateApiClient(api, "https://business.example/api/v1/");
+        return new EstimateEditionPageViewModel(query ?? SampleQuery(), client);
+    }
+
+    [Fact]
+    public void Constructor_prefills_description_and_adds_a_first_line()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+
+        Assert.Equal("Coupe simple", vm.EstimateDescription);
+        Assert.Single(vm.Lines);
+        Assert.Same(vm.Lines[0], vm.SelectedLine);
+        Assert.Contains("#42", vm.ContextLabel);
+        Assert.Contains("cli-1", vm.ContextLabel);
+    }
+
+    [Fact]
+    public void AddLine_appends_and_selects_the_new_line()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+
+        vm.AddLineCommand.Execute(null);
+
+        Assert.Equal(2, vm.Lines.Count);
+        Assert.Same(vm.Lines[1], vm.SelectedLine);
+    }
+
+    [Fact]
+    public void RemoveLine_removes_the_selected_line()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        var first = vm.Lines[0];
+
+        vm.RemoveLineCommand.Execute(null);
+
+        Assert.Empty(vm.Lines);
+        Assert.Null(vm.SelectedLine);
+        Assert.False(vm.RemoveLineCommand.CanExecute(null));
+        Assert.DoesNotContain(first, vm.Lines);
+    }
+
+    [Fact]
+    public void Total_sums_line_totals_and_tracks_edits()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+
+        vm.Lines[0].Count = 2;
+        vm.Lines[0].UnitaryCost = 15.5m;
+
+        Assert.Equal(31m, vm.Total);
+        Assert.Equal($"{31m:0.00} EUR", vm.TotalLabel);
+
+        vm.AddLineCommand.Execute(null);
+        vm.Lines[1].Count = 1;
+        vm.Lines[1].UnitaryCost = 9m;
+
+        Assert.Equal(40m, vm.Total);
+    }
+
+    [Fact]
+    public async Task Send_without_title_warns_and_does_not_post()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.Lines[0].Name = "Coupe";
+        vm.Lines[0].Description = "Coupe simple";
+        vm.Lines[0].UnitaryCost = 25m;
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.Null(api.LastBody);
+        Assert.Equal(StatusSeverity.Warning, vm.ActionStatus.Severity);
+        Assert.Contains("titre", vm.ActionStatus.Message);
+    }
+
+    [Fact]
+    public async Task Send_without_any_line_warns_and_does_not_post()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "Devis coupe";
+        vm.Lines.Clear();
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.Null(api.LastBody);
+        Assert.Equal(StatusSeverity.Warning, vm.ActionStatus.Severity);
+        Assert.Contains("ligne", vm.ActionStatus.Message);
+    }
+
+    [Fact]
+    public async Task Send_with_a_blank_line_name_warns_and_does_not_post()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "Devis coupe";
+        vm.Lines[0].Description = "Oubli du nom";
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.Null(api.LastBody);
+        Assert.Equal(StatusSeverity.Warning, vm.ActionStatus.Severity);
+        Assert.Contains("nom", vm.ActionStatus.Message);
+    }
+
+    [Fact]
+    public async Task Send_posts_the_estimate_payload_to_the_estimate_route()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "  Devis coupe  ";
+        vm.Lines[0].Name = "Coupe";
+        vm.Lines[0].Description = "Coupe simple";
+        vm.Lines[0].Count = 2.4m;
+        vm.Lines[0].UnitaryCost = 25m;
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.Equal("https://business.example/api/v1/estimate", api.LastPath);
+        Assert.Equal(HttpMethod.Post, api.LastMethod);
+
+        var payload = Assert.IsType<EstimateDto>(api.LastBody);
+        Assert.Equal(42, payload.CommandId);
+        Assert.Equal("cli-1", payload.ClientId);
+        Assert.Equal("Brush", payload.CommandType);
+        Assert.Equal("Devis coupe", payload.Title);
+        Assert.Equal("Coupe simple", payload.Description);
+        Assert.Empty(payload.AttachedFiles);
+        Assert.Empty(payload.AttachedGraphics);
+
+        var line = Assert.Single(payload.Bill);
+        Assert.Equal("Coupe", line.Name);
+        Assert.Equal(2, line.Count);
+        Assert.Equal(25m, line.UnitaryCost);
+        Assert.Equal("EUR", line.Currency);
+    }
+
+    [Fact]
+    public async Task Send_marks_the_page_as_sent_and_disables_resend()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "Devis coupe";
+        vm.Lines[0].Name = "Coupe";
+        vm.Lines[0].Description = "Coupe simple";
+        vm.Lines[0].UnitaryCost = 25m;
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.True(vm.HasSent);
+        Assert.False(vm.SendCommand.CanExecute(null));
+        Assert.Equal("Devis envoyé", vm.SendLabel);
+        Assert.Equal(StatusSeverity.Info, vm.ActionStatus.Severity);
+        Assert.Contains("#7", vm.ActionStatus.Message);
+    }
+
+    [Fact]
+    public async Task Send_surfaces_server_errors_as_error_status()
+    {
+        var api = new StubEstimateApi { Failure = new HttpRequestException("boom", null, System.Net.HttpStatusCode.InternalServerError) };
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "Devis coupe";
+        vm.Lines[0].Name = "Coupe";
+        vm.Lines[0].Description = "Coupe simple";
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        Assert.False(vm.HasSent);
+        Assert.Equal(StatusSeverity.Error, vm.ActionStatus.Severity);
+        Assert.True(vm.SendCommand.CanExecute(null));
+    }
+
+    [Fact]
+    public async Task Send_accepts_negative_amounts_for_discount_lines()
+    {
+        var api = new StubEstimateApi();
+        var vm = CreateViewModel(api);
+        vm.EstimateTitle = "Devis avec remise";
+        vm.Lines[0].Name = "Coupe";
+        vm.Lines[0].Description = "Coupe simple";
+        vm.Lines[0].UnitaryCost = 25m;
+
+        vm.AddLineCommand.Execute(null);
+        vm.Lines[1].Name = "Remise fidélité";
+        vm.Lines[1].Description = "Remise client régulier";
+        vm.Lines[1].UnitaryCost = -5m;
+
+        Assert.Equal(20m, vm.Total);
+
+        await vm.SendCommand.ExecuteAsync(null);
+
+        var payload = Assert.IsType<EstimateDto>(api.LastBody);
+        Assert.Equal(2, payload.Bill.Count);
+        Assert.Equal(-5m, payload.Bill[1].UnitaryCost);
+        Assert.True(vm.HasSent);
+    }
+
+    private sealed class StubEstimateApi : IYavscApiClient
+    {
+        public HttpClient Http { get; } = new();
+        public string? LastPath { get; private set; }
+        public HttpMethod? LastMethod { get; private set; }
+        public object? LastBody { get; private set; }
+        public Exception? Failure { get; init; }
+
+        public Task<T> CallAsync<T>(HttpMethod method, string path, object? body = null, CancellationToken ct = default)
+        {
+            LastMethod = method;
+            LastPath = path;
+            LastBody = body;
+
+            if (Failure is not null)
+            {
+                throw Failure;
+            }
+
+            if (typeof(T) == typeof(EstimateCreatedDto))
+            {
+                var payload = (EstimateDto)body!;
+                var created = new EstimateCreatedDto { Id = 7, Bill = payload.Bill };
+                return Task.FromResult((T)(object)created);
+            }
+
+            return Task.FromResult(default(T)!);
+        }
+
+        public Task CallAsync(HttpMethod method, string path, object? body = null, CancellationToken ct = default)
+        {
+            LastMethod = method;
+            LastPath = path;
+            LastBody = body;
+            return Task.CompletedTask;
+        }
+
+        public Task<T> CallAsync<T>(HttpMethod method, string path, Func<HttpContent> contentFactory, CancellationToken ct = default)
+            => CallAsync<T>(method, path, (object?)null, ct);
+
+        public Task CallAsync(HttpMethod method, string path, Func<HttpContent> contentFactory, CancellationToken ct = default)
+            => CallAsync(method, path, (object?)null, ct);
+
+        public ValueTask DisposeAsync() => ValueTask.CompletedTask;
+    }
+}
diff --git a/src/PostIt/PostIt.Tests/PostItViewModelTests.cs b/src/PostIt/PostIt.Tests/PostItViewModelTests.cs
index 821a778dd..8ecc5bb55 100644
--- a/src/PostIt/PostIt.Tests/PostItViewModelTests.cs
+++ b/src/PostIt/PostIt.Tests/PostItViewModelTests.cs
@@ -23,13 +23,11 @@ public class PostItViewModelTests
         viewModel.Posts.Add(new BlogPostDto { Id = 3, Title = "Third post", Article = "Search me", AuthorId = "carol" });
 
         viewModel.SearchText = "search";
-        viewModel.SearchCommand.Execute(null);
 
         Assert.Single(viewModel.FilteredPosts);
         Assert.Equal(3, viewModel.FilteredPosts[0].Id);
 
         viewModel.SearchText = "bob";
-        viewModel.SearchCommand.Execute(null);
 
         Assert.Single(viewModel.FilteredPosts);
         Assert.Equal(2, viewModel.FilteredPosts[0].Id);
diff --git a/src/PostIt/PostIt.Tests/ProviderOngoingRequestsPageViewModelTests.cs b/src/PostIt/PostIt.Tests/ProviderOngoingRequestsPageViewModelTests.cs
index 945072870..cfb300316 100644
--- a/src/PostIt/PostIt.Tests/ProviderOngoingRequestsPageViewModelTests.cs
+++ b/src/PostIt/PostIt.Tests/ProviderOngoingRequestsPageViewModelTests.cs
@@ -126,6 +126,36 @@ public class ProviderOngoingRequestsPageViewModelTests
         Assert.Equal(ProviderOngoingRequestsPageViewModel.SortByDate, vm.SelectedSortOption);
     }
 
+    [Fact]
+    public async Task CreateEstimateForSelectedCommand_requires_a_selection()
+    {
+        var api = new StubProviderApi();
+        var client = new BillingApiClient(api, "https://business.example/api/v1/");
+        var estimateClient = new EstimateApiClient(api, "https://business.example/api/v1/");
+        var vm = new ProviderOngoingRequestsPageViewModel(client, estimateClient: estimateClient);
+
+        await vm.InitializeAsync();
+
+        Assert.False(vm.CreateEstimateForSelectedCommand.CanExecute(null));
+
+        vm.SelectedQuery = vm.Queries[0];
+
+        Assert.True(vm.CreateEstimateForSelectedCommand.CanExecute(null));
+    }
+
+    [Fact]
+    public async Task CreateEstimateForSelectedCommand_is_disabled_without_estimate_client()
+    {
+        var api = new StubProviderApi();
+        var client = new BillingApiClient(api, "https://business.example/api/v1/");
+        var vm = new ProviderOngoingRequestsPageViewModel(client);
+
+        await vm.InitializeAsync();
+        vm.SelectedQuery = vm.Queries[0];
+
+        Assert.False(vm.CreateEstimateForSelectedCommand.CanExecute(null));
+    }
+
     private sealed class StubProviderApi : IYavscApiClient
     {
         public HttpClient Http { get; } = new();
diff --git a/src/PostIt/PostIt/Helpers/ServiceCollectionHelpers.cs b/src/PostIt/PostIt/Helpers/ServiceCollectionHelpers.cs
index 0ebd2af19..6bd54ca20 100644
--- a/src/PostIt/PostIt/Helpers/ServiceCollectionHelpers.cs
+++ b/src/PostIt/PostIt/Helpers/ServiceCollectionHelpers.cs
@@ -30,6 +30,7 @@ public static class ServiceCollectionHelpers
             () => settings.ApiUrl,
             () => settings.Authentication?.Authority);
         var billingClient = new BillingApiClient(api, () => settings.ApiUrl);
+        var estimateClient = new EstimateApiClient(api, () => settings.ApiUrl);
         var userDirectory = new UserDirectory(userSearchClient);
         var reverseGeocoding = new NominatimReverseGeocodingService();
 
@@ -60,6 +61,8 @@ public static class ServiceCollectionHelpers
         services.AddTransient<BillingQueriesPage>();
         services.AddTransient<BillingQueryDetailsPage>();
         services.AddTransient<ProviderOngoingRequestsPage>();
+        services.AddTransient<EstimateEditionPage>();
+
         // ViewModels
         services.AddSingleton(settings);
         services.AddSingleton<YavscApiClient>(api);
@@ -69,6 +72,7 @@ public static class ServiceCollectionHelpers
         services.AddSingleton(userSearchClient);
         services.AddSingleton(activityClient);
         services.AddSingleton(billingClient);
+        services.AddSingleton(estimateClient);
         services.AddSingleton<IReverseGeocodingService>(reverseGeocoding);
         services.AddSingleton<IUserDirectory>(userDirectory);
         services.AddSingleton<HomePageViewModel>();
diff --git a/src/PostIt/PostIt/ViewLocator.cs b/src/PostIt/PostIt/ViewLocator.cs
index 72bd2559e..6f8c5d902 100644
--- a/src/PostIt/PostIt/ViewLocator.cs
+++ b/src/PostIt/PostIt/ViewLocator.cs
@@ -53,6 +53,7 @@ public class ViewLocator : IDataTemplate
             BillingQueriesPageViewModel => services.GetRequiredService<BillingQueriesPage>(),
             BillingQueryDetailsPageViewModel => services.GetRequiredService<BillingQueryDetailsPage>(),
             ProviderOngoingRequestsPageViewModel => services.GetRequiredService<ProviderOngoingRequestsPage>(),
+            EstimateEditionPageViewModel => services.GetRequiredService<EstimateEditionPage>(),
             null => new TextBlock { Text = "No view for <null>" },
             _ => new TextBlock { Text = $"No view for {data.GetType().Name}" }
         };
diff --git a/src/PostIt/PostIt/ViewModels/Activity/EstimateEditionPageViewModel.cs b/src/PostIt/PostIt/ViewModels/Activity/EstimateEditionPageViewModel.cs
new file mode 100644
index 000000000..8f007dc08
--- /dev/null
+++ b/src/PostIt/PostIt/ViewModels/Activity/EstimateEditionPageViewModel.cs
@@ -0,0 +1,293 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Avalonia;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using PostIt.Helpers;
+using Yavsc.Api.Client;
+
+namespace PostIt.ViewModels;
+
+/// <summary>
+/// Edition d'un devis (<c>Estimate</c>) créé en réponse à une demande
+/// client (<see cref="BillingQuerySummaryDto"/>) consultée depuis la
+/// page « Mes demandes en cours ». L'envoi poste le devis sur
+/// <c>api/v1/estimate</c>; côté serveur, la commande liée
+/// (<see cref="BillingQuerySummaryDto.Id"/>) est alors marquée comme
+/// validée par le prestataire.
+/// </summary>
+public partial class EstimateEditionPageViewModel : ViewModelBase, IActionStatusViewModel
+{
+    private readonly EstimateApiClient _estimateClient;
+    private readonly BillingQuerySummaryDto _query;
+
+    public long QueryId => _query.Id;
+    public string ClientId => _query.ClientId;
+    public string BillingCode => _query.BillingCode;
+
+    public string Title => $"Devis — demande #{_query.Id}";
+
+    public string ContextLabel
+        => $"Demande #{_query.Id} · {BillingCode} · client {ClientId}";
+
+    public string QueryDescription => string.IsNullOrWhiteSpace(_query.Description)
+        ? "(sans description)"
+        : _query.Description;
+
+    [ObservableProperty]
+    public partial string EstimateTitle { get; set; } = string.Empty;
+
+    [ObservableProperty]
+    public partial string EstimateDescription { get; set; } = string.Empty;
+
+    [ObservableProperty]
+    public partial ObservableCollection<EstimateLineItemViewModel> Lines { get; set; } = new();
+
+    [ObservableProperty, NotifyCanExecuteChangedFor(nameof(RemoveLineCommand))]
+    public partial EstimateLineItemViewModel? SelectedLine { get; set; }
+
+    [ObservableProperty, NotifyCanExecuteChangedFor(nameof(SendCommand))]
+    public partial bool IsBusy { get; set; }
+
+    /// <summary>
+    /// True une fois le devis accepté par le serveur: l'envoi est
+    /// désactivé pour éviter les doublons, il ne reste que « Retour ».
+    /// </summary>
+    [ObservableProperty, NotifyCanExecuteChangedFor(nameof(SendCommand))]
+    public partial bool HasSent { get; set; }
+
+    [ObservableProperty]
+    public partial string StatusMessage { get; set; } = "Prêt.";
+
+    [ObservableProperty]
+    public partial StatusNotice ActionStatus { get; set; } = StatusNotice.Info("Prêt.");
+
+    public decimal Total => Lines.Sum(line => line.LineTotal);
+
+    public string TotalLabel => $"{Total:0.00} {Lines.FirstOrDefault()?.Currency ?? "EUR"}";
+
+    public string SendLabel => HasSent ? "Devis envoyé" : "Envoyer le devis";
+
+    public override bool CanNavigateNext
+    {
+        get => false;
+        protected set { _ = value; }
+    }
+
+    public override bool CanNavigatePrevious
+    {
+        get => true;
+        protected set { _ = value; }
+    }
+
+    public EstimateEditionPageViewModel(BillingQuerySummaryDto query, EstimateApiClient estimateClient)
+    {
+        _query = query ?? throw new ArgumentNullException(nameof(query));
+        _estimateClient = estimateClient ?? throw new ArgumentNullException(nameof(estimateClient));
+
+        EstimateDescription = query.Description ?? string.Empty;
+        Lines.CollectionChanged += OnLinesCollectionChanged;
+
+        AddLine();
+        this.SetInfoStatus("Complétez le devis puis envoyez-le. La demande associée sera validée.");
+    }
+
+    [RelayCommand]
+    private void AddLine()
+    {
+        var line = new EstimateLineItemViewModel();
+        Lines.Add(line);
+        SelectedLine = line;
+    }
+
+    private bool CanRemoveLine() => SelectedLine is not null && !IsBusy && !HasSent;
+
+    [RelayCommand(CanExecute = nameof(CanRemoveLine))]
+    private void RemoveLine()
+    {
+        if (SelectedLine is null)
+        {
+            return;
+        }
+
+        var index = Lines.IndexOf(SelectedLine);
+        Lines.Remove(SelectedLine);
+        SelectedLine = Lines.Count == 0
+            ? null
+            : Lines[Math.Min(index, Lines.Count - 1)];
+    }
+
+    private bool CanSend() => !IsBusy && !HasSent;
+
+    [RelayCommand(CanExecute = nameof(CanSend))]
+    private async Task SendAsync()
+    {
+        if (!TryValidate(out var validationMessage))
+        {
+            this.SetWarningStatus(validationMessage);
+            return;
+        }
+
+        IsBusy = true;
+        try
+        {
+            var payload = BuildPayload();
+            var created = await _estimateClient.CreateAsync(payload).ConfigureAwait(true);
+
+            HasSent = true;
+            OnPropertyChanged(nameof(SendLabel));
+            this.SetInfoStatus(
+                $"Devis #{created.Id} envoyé ({created.Bill.Count} ligne(s)). La demande #{QueryId} est validée.");
+        }
+        catch (HttpRequestException ex) when (ex.StatusCode is HttpStatusCode.Unauthorized or HttpStatusCode.Forbidden)
+        {
+            this.SetWarningStatus("Accès refusé à l'API devis (scope 'api'). Déconnectez puis reconnectez-vous.");
+        }
+        catch (Exception ex)
+        {
+            this.SetErrorStatus($"Erreur lors de l'envoi du devis: {ex.Message}");
+        }
+        finally
+        {
+            IsBusy = false;
+        }
+    }
+
+    [RelayCommand]
+    private async Task BackAsync()
+    {
+        var app = (App?)Application.Current;
+        if (app is null)
+        {
+            throw new InvalidOperationException("Application PostIt indisponible.");
+        }
+
+        await app.GoBackAsync().ConfigureAwait(true);
+    }
+
+    internal EstimateDto BuildPayload()
+    {
+        return new EstimateDto
+        {
+            CommandId = QueryId,
+            ClientId = ClientId,
+            CommandType = BillingCode,
+            Title = EstimateTitle.Trim(),
+            Description = EstimateDescription.Trim(),
+            Bill = Lines.Select(line => new EstimateLineDto
+            {
+                Id = line.Id,
+                Name = line.Name.Trim(),
+                Description = line.Description.Trim(),
+                Count = Math.Max(1, (int)Math.Round(line.Count)),
+                UnitaryCost = line.UnitaryCost,
+                Currency = string.IsNullOrWhiteSpace(line.Currency) ? "EUR" : line.Currency.Trim(),
+            }).ToList(),
+        };
+    }
+
+    private bool TryValidate(out string message)
+    {
+        if (string.IsNullOrWhiteSpace(EstimateTitle))
+        {
+            message = "Le titre du devis est requis.";
+            return false;
+        }
+
+        if (string.IsNullOrWhiteSpace(ClientId))
+        {
+            message = "La demande sélectionnée n'identifie pas de client.";
+            return false;
+        }
+
+        if (string.IsNullOrWhiteSpace(BillingCode))
+        {
+            message = "La demande sélectionnée n'a pas de code de facturation.";
+            return false;
+        }
+
+        if (Lines.Count == 0)
+        {
+            message = "Ajoutez au moins une ligne au devis.";
+            return false;
+        }
+
+        foreach (var line in Lines)
+        {
+            if (string.IsNullOrWhiteSpace(line.Name))
+            {
+                message = "Chaque ligne doit avoir un nom.";
+                return false;
+            }
+
+            if (line.Name.Trim().Length > 256)
+            {
+                message = $"Le nom de la ligne « {line.Name.Trim()[..20]}… » dépasse 256 caractères.";
+                return false;
+            }
+
+            if (string.IsNullOrWhiteSpace(line.Description))
+            {
+                message = $"La ligne « {line.Name.Trim()} » doit avoir une description.";
+                return false;
+            }
+
+            if (line.Description.Trim().Length > 512)
+            {
+                message = $"La description de la ligne « {line.Name.Trim()} » dépasse 512 caractères.";
+                return false;
+            }
+
+            if (line.Count < 1)
+            {
+                message = $"La quantité de la ligne « {line.Name.Trim()} » doit être d'au moins 1.";
+                return false;
+            }
+        }
+
+        message = string.Empty;
+        return true;
+    }
+
+    private void OnLinesCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if (e.OldItems is not null)
+        {
+            foreach (var item in e.OldItems.OfType<EstimateLineItemViewModel>())
+            {
+                item.PropertyChanged -= OnLinePropertyChanged;
+            }
+        }
+
+        if (e.NewItems is not null)
+        {
+            foreach (var item in e.NewItems.OfType<EstimateLineItemViewModel>())
+            {
+                item.PropertyChanged += OnLinePropertyChanged;
+            }
+        }
+
+        RaiseTotalsChanged();
+    }
+
+    private void OnLinePropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName is nameof(EstimateLineItemViewModel.LineTotal)
+            or nameof(EstimateLineItemViewModel.Currency))
+        {
+            RaiseTotalsChanged();
+        }
+    }
+
+    private void RaiseTotalsChanged()
+    {
+        OnPropertyChanged(nameof(Total));
+        OnPropertyChanged(nameof(TotalLabel));
+    }
+}
diff --git a/src/PostIt/PostIt/ViewModels/Activity/EstimateLineItemViewModel.cs b/src/PostIt/PostIt/ViewModels/Activity/EstimateLineItemViewModel.cs
new file mode 100644
index 000000000..864906cdd
--- /dev/null
+++ b/src/PostIt/PostIt/ViewModels/Activity/EstimateLineItemViewModel.cs
@@ -0,0 +1,35 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace PostIt.ViewModels;
+
+/// <summary>
+/// Editable estimate line. <see cref="Count"/> is exposed as a
+/// <see cref="decimal"/> so it binds directly to
+/// <c>NumericUpDown.Value</c> (<c>decimal?</c>); it is rounded back
+/// to an integer when the DTO is built.
+/// </summary>
+public partial class EstimateLineItemViewModel : ObservableObject
+{
+    public long Id { get; set; }
+
+    [ObservableProperty]
+    public partial string Name { get; set; } = string.Empty;
+
+    [ObservableProperty]
+    public partial string Description { get; set; } = string.Empty;
+
+    [ObservableProperty, NotifyPropertyChangedFor(nameof(LineTotal))]
+    [NotifyPropertyChangedFor(nameof(LineTotalLabel))]
+    public partial decimal Count { get; set; } = 1m;
+
+    [ObservableProperty, NotifyPropertyChangedFor(nameof(LineTotal))]
+    [NotifyPropertyChangedFor(nameof(LineTotalLabel))]
+    public partial decimal UnitaryCost { get; set; }
+
+    [ObservableProperty]
+    public partial string Currency { get; set; } = "EUR";
+
+    public decimal LineTotal => Count * UnitaryCost;
+
+    public string LineTotalLabel => $"{LineTotal:0.00}";
+}
diff --git a/src/PostIt/PostIt/ViewModels/Activity/ProviderOngoingRequestsPageViewModel.cs b/src/PostIt/PostIt/ViewModels/Activity/ProviderOngoingRequestsPageViewModel.cs
index 562f24988..71e979e66 100644
--- a/src/PostIt/PostIt/ViewModels/Activity/ProviderOngoingRequestsPageViewModel.cs
+++ b/src/PostIt/PostIt/ViewModels/Activity/ProviderOngoingRequestsPageViewModel.cs
@@ -22,6 +22,7 @@ public partial class ProviderOngoingRequestsPageViewModel : ViewModelBase, IActi
     public const string SortByStatus = "Statut (en cours d'abord)";
 
     private readonly BillingApiClient _billingClient;
+    private readonly EstimateApiClient? _estimateClient;
     private readonly Settings? _settings;
     private List<BillingQuerySummaryDto> _allQueries = new();
 
@@ -42,6 +43,8 @@ public partial class ProviderOngoingRequestsPageViewModel : ViewModelBase, IActi
     public partial string SelectedSortOption { get; set; } = SortByDate;
 
     [ObservableProperty, NotifyCanExecuteChangedFor(nameof(OpenSelectedQueryCommand))]
+    [NotifyCanExecuteChangedFor(nameof(OpenSelectedEditorCommand))]
+    [NotifyCanExecuteChangedFor(nameof(CreateEstimateForSelectedCommand))]
     public partial BillingQuerySummaryDto? SelectedQuery { get; set; }
 
     [ObservableProperty]
@@ -67,9 +70,13 @@ public partial class ProviderOngoingRequestsPageViewModel : ViewModelBase, IActi
         protected set { _ = value; }
     }
 
-    public ProviderOngoingRequestsPageViewModel(BillingApiClient billingClient, Settings? settings = null)
+    public ProviderOngoingRequestsPageViewModel(
+        BillingApiClient billingClient,
+        Settings? settings = null,
+        EstimateApiClient? estimateClient = null)
     {
         _billingClient = billingClient ?? throw new ArgumentNullException(nameof(billingClient));
+        _estimateClient = estimateClient;
         _settings = settings;
 
         if (_settings is not null)
@@ -210,6 +217,33 @@ public partial class ProviderOngoingRequestsPageViewModel : ViewModelBase, IActi
         }
     }
 
+    private bool CanCreateEstimateForSelected() => SelectedQuery is not null && _estimateClient is not null;
+
+    [RelayCommand(CanExecute = nameof(CanCreateEstimateForSelected))]
+    public async Task CreateEstimateForSelectedAsync()
+    {
+        if (SelectedQuery is null)
+        {
+            this.SetWarningStatus("Sélectionnez une demande.");
+            return;
+        }
+
+        if (_estimateClient is null)
+        {
+            this.SetWarningStatus("Le client devis n'est pas disponible.");
+            return;
+        }
+
+        var app = (App?)Application.Current;
+        if (app is null)
+        {
+            throw new InvalidOperationException("Application PostIt indisponible.");
+        }
+
+        var vm = new EstimateEditionPageViewModel(SelectedQuery, _estimateClient);
+        await app.PushPageAsync(vm).ConfigureAwait(true);
+    }
+
     partial void OnFilterTextChanged(string value)
     {
         ApplyFilter();
diff --git a/src/PostIt/PostIt/ViewModels/Layout/HomePageViewModel.cs b/src/PostIt/PostIt/ViewModels/Layout/HomePageViewModel.cs
index 673177863..fd2ff1091 100644
--- a/src/PostIt/PostIt/ViewModels/Layout/HomePageViewModel.cs
+++ b/src/PostIt/PostIt/ViewModels/Layout/HomePageViewModel.cs
@@ -65,7 +65,9 @@ public class HomePageViewModel : ViewModelBase
             throw new InvalidOperationException("Client billing indisponible.");
         }
 
-        var vm = new ProviderOngoingRequestsPageViewModel(billingClient, Settings);
+        var estimateClient = app.ServiceProvider?.GetRequiredService<EstimateApiClient>();
+
+        var vm = new ProviderOngoingRequestsPageViewModel(billingClient, Settings, estimateClient);
         await vm.InitializeAsync();
         await app.PushPageAsync(vm);
     }
diff --git a/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml b/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml
new file mode 100644
index 000000000..7b25ab226
--- /dev/null
+++ b/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml
@@ -0,0 +1,151 @@
+<ContentPage xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="using:PostIt.ViewModels"
+             xmlns:postitControls="using:PostIt.Controls"
+             x:Class="PostIt.Views.EstimateEditionPage"
+             x:DataType="vm:EstimateEditionPageViewModel"
+             Header="Edition de devis">
+    <Grid RowDefinitions="Auto,Auto,*,Auto" Margin="12">
+        <StackPanel Grid.Row="0" Spacing="3">
+            <TextBlock Text="{Binding Title}"
+                       FontSize="20"
+                       FontWeight="Bold" />
+            <TextBlock Text="{Binding ContextLabel}" Opacity="0.75" />
+        </StackPanel>
+
+        <Grid Grid.Row="1" ColumnDefinitions="Auto,8,*" Margin="0,10,0,8">
+            <Button Grid.Column="0"
+                    Content="Retour"
+                    Command="{Binding BackCommand}" />
+        </Grid>
+
+        <ScrollViewer Grid.Row="2">
+            <StackPanel Spacing="10">
+                <Border BorderThickness="1"
+                        BorderBrush="#22000000"
+                        CornerRadius="8"
+                        Padding="10">
+                    <Grid ColumnDefinitions="Auto,12,*" RowDefinitions="Auto,Auto,Auto" RowSpacing="8">
+                        <TextBlock Grid.Row="0"
+                                   Grid.Column="0"
+                                   Text="Demande"
+                                   FontWeight="SemiBold"
+                                   VerticalAlignment="Center" />
+                        <TextBlock Grid.Row="0"
+                                   Grid.Column="2"
+                                   Text="{Binding QueryDescription}"
+                                   TextWrapping="Wrap"
+                                   Opacity="0.75" />
+
+                        <TextBlock Grid.Row="1"
+                                   Grid.Column="0"
+                                   Text="Titre"
+                                   FontWeight="SemiBold"
+                                   VerticalAlignment="Center" />
+                        <TextBox Grid.Row="1"
+                                 Grid.Column="2"
+                                 Text="{Binding EstimateTitle}"
+                                 PlaceholderText="Titre du devis" />
+
+                        <TextBlock Grid.Row="2"
+                                   Grid.Column="0"
+                                   Text="Description"
+                                   FontWeight="SemiBold"
+                                   VerticalAlignment="Top" />
+                        <TextBox Grid.Row="2"
+                                 Grid.Column="2"
+                                 Text="{Binding EstimateDescription}"
+                                 PlaceholderText="Description détaillée du devis"
+                                 AcceptsReturn="True"
+                                 TextWrapping="Wrap"
+                                 MinHeight="70" />
+                    </Grid>
+                </Border>
+
+                <Border BorderThickness="1"
+                        BorderBrush="#22000000"
+                        CornerRadius="8"
+                        Padding="10">
+                    <StackPanel Spacing="8">
+                        <Grid ColumnDefinitions="*,Auto,8,Auto">
+                            <TextBlock Grid.Column="0"
+                                       Text="Lignes du devis"
+                                       FontWeight="SemiBold"
+                                       VerticalAlignment="Center" />
+                            <Button Grid.Column="1"
+                                    Content="Ajouter une ligne"
+                                    Command="{Binding AddLineCommand}" />
+                            <Button Grid.Column="3"
+                                    Content="Retirer la ligne"
+                                    Command="{Binding RemoveLineCommand}" />
+                        </Grid>
+
+                        <ListBox ItemsSource="{Binding Lines}"
+                                 SelectedItem="{Binding SelectedLine, Mode=TwoWay}">
+                            <ListBox.ItemTemplate>
+                                <DataTemplate x:DataType="vm:EstimateLineItemViewModel">
+                                    <Border BorderThickness="1"
+                                            BorderBrush="#22000000"
+                                            CornerRadius="6"
+                                            Padding="8"
+                                            Margin="0,0,0,8">
+                                        <Grid ColumnDefinitions="*,8,110,8,130,8,90"
+                                              RowDefinitions="Auto,Auto"
+                                              RowSpacing="6">
+                                            <TextBox Grid.Row="0"
+                                                     Grid.Column="0"
+                                                     Text="{Binding Name}"
+                                                     PlaceholderText="Nom de la ligne" />
+                                            <NumericUpDown Grid.Row="0"
+                                                           Grid.Column="2"
+                                                           Value="{Binding Count}"
+                                                           Minimum="1"
+                                                           Increment="1"
+                                                           FormatString="0" />
+                                            <NumericUpDown Grid.Row="0"
+                                                           Grid.Column="4"
+                                                           Value="{Binding UnitaryCost}"
+                                                           Increment="0.5"
+                                                           FormatString="0.00" />
+                                            <TextBlock Grid.Row="0"
+                                                       Grid.Column="6"
+                                                       Text="{Binding LineTotalLabel}"
+                                                       VerticalAlignment="Center"
+                                                       HorizontalAlignment="Right"
+                                                       FontWeight="SemiBold" />
+                                            <TextBox Grid.Row="1"
+                                                     Grid.Column="0"
+                                                     Grid.ColumnSpan="7"
+                                                     Text="{Binding Description}"
+                                                     PlaceholderText="Description de la ligne" />
+                                        </Grid>
+                                    </Border>
+                                </DataTemplate>
+                            </ListBox.ItemTemplate>
+                        </ListBox>
+
+                        <Grid ColumnDefinitions="*,Auto">
+                            <TextBlock Grid.Column="1"
+                                       Text="{Binding TotalLabel, StringFormat='Total : {0}'}"
+                                       FontSize="16"
+                                       FontWeight="Bold"
+                                       HorizontalAlignment="Right" />
+                        </Grid>
+                    </StackPanel>
+                </Border>
+            </StackPanel>
+        </ScrollViewer>
+
+        <Grid Grid.Row="3" ColumnDefinitions="Auto,8,*,Auto" Margin="0,12,0,0">
+            <Button Grid.Column="0"
+                    Content="{Binding SendLabel}"
+                    Command="{Binding SendCommand}" />
+            <postitControls:StatusBar Grid.Column="2"
+                                      DataContext="{Binding ActionStatus}" />
+            <ProgressBar Grid.Column="3"
+                         Width="120"
+                         IsIndeterminate="True"
+                         IsVisible="{Binding IsBusy}" />
+        </Grid>
+    </Grid>
+</ContentPage>
diff --git a/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml.cs b/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml.cs
new file mode 100644
index 000000000..1c58efa10
--- /dev/null
+++ b/src/PostIt/PostIt/Views/Activity/EstimateEditionPage.axaml.cs
@@ -0,0 +1,17 @@
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace PostIt.Views;
+
+public partial class EstimateEditionPage : ContentPage
+{
+    public EstimateEditionPage()
+    {
+        InitializeComponent();
+    }
+
+    private void InitializeComponent()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+}
diff --git a/src/PostIt/PostIt/Views/Activity/ProviderOngoingRequestsPage.axaml b/src/PostIt/PostIt/Views/Activity/ProviderOngoingRequestsPage.axaml
index e6db2988b..173fe903b 100644
--- a/src/PostIt/PostIt/Views/Activity/ProviderOngoingRequestsPage.axaml
+++ b/src/PostIt/PostIt/Views/Activity/ProviderOngoingRequestsPage.axaml
@@ -87,6 +87,9 @@
                 <Button Content="Ouvrir en édition"
                     Command="{Binding OpenSelectedEditorCommand}"
                     />
+                <Button Content="Créer un devis"
+                    Command="{Binding CreateEstimateForSelectedCommand}"
+                    />
                 </StackPanel>
         </Grid>
 
diff --git a/src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml b/src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml
index 34a991c25..d4124a651 100644
--- a/src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml
+++ b/src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml
@@ -15,10 +15,11 @@
   <Design.DataContext>
     <vm:BlogsViewModel />
   </Design.DataContext>
-  <ScrollViewer VerticalScrollBarVisibility="Visible"
-              HorizontalScrollBarVisibility="Disabled"
-      Padding="5"
-      Margin="5"
+  <ScrollViewer
+  VerticalScrollBarVisibility="Visible"
+  HorizontalScrollBarVisibility="Disabled"
+  Padding="5"
+  Margin="5"
       >
   <StackPanel HorizontalAlignment="Stretch">
     <StackPanel Orientation="Horizontal" Spacing="10" Margin="5">
diff --git a/src/Yavsc.Api.Client/Dtos/EstimateDtos.cs b/src/Yavsc.Api.Client/Dtos/EstimateDtos.cs
new file mode 100644
index 000000000..43c09d94a
--- /dev/null
+++ b/src/Yavsc.Api.Client/Dtos/EstimateDtos.cs
@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+
+namespace Yavsc.Api.Client;
+
+/// <summary>
+/// A single billable line of an estimate, mirroring the JSON shape of
+/// the server-side <c>Yavsc.Models.Billing.CommandLine</c> entity.
+/// </summary>
+public sealed class EstimateLineDto
+{
+    public long Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string Description { get; set; } = string.Empty;
+    public int Count { get; set; } = 1;
+    public decimal UnitaryCost { get; set; }
+    public long EstimateId { get; set; }
+    public string Currency { get; set; } = "EUR";
+}
+
+/// <summary>
+/// Estimate payload exchanged with the <c>api/v1/estimate</c> routes
+/// (<c>EstimateApiController</c>). <see cref="AttachedGraphics"/> and
+/// <see cref="AttachedFiles"/> are always initialised: the server-side
+/// entity reads them from non-nullable string properties and a null
+/// list would break its serialisation.
+/// </summary>
+public sealed class EstimateDto
+{
+    public long Id { get; set; }
+    public long? CommandId { get; set; }
+    public string Title { get; set; } = string.Empty;
+    public string Description { get; set; } = string.Empty;
+    public List<EstimateLineDto> Bill { get; set; } = new();
+    public List<string> AttachedGraphics { get; set; } = new();
+    public List<string> AttachedFiles { get; set; } = new();
+    public string? OwnerId { get; set; }
+    public string ClientId { get; set; } = string.Empty;
+    public string CommandType { get; set; } = string.Empty;
+    public DateTime ProviderValidationDate { get; set; }
+    public DateTime ClientValidationDate { get; set; }
+}
+
+/// <summary>
+/// Response of a successful estimate creation
+/// (<c>Ok(new { estimate.Id, estimate.Bill })</c>).
+/// </summary>
+public sealed class EstimateCreatedDto
+{
+    public long Id { get; set; }
+    public List<EstimateLineDto> Bill { get; set; } = new();
+}
diff --git a/src/Yavsc.Api.Client/EstimateApiClient.cs b/src/Yavsc.Api.Client/EstimateApiClient.cs
new file mode 100644
index 000000000..15b260786
--- /dev/null
+++ b/src/Yavsc.Api.Client/EstimateApiClient.cs
@@ -0,0 +1,110 @@
+using System;
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Yavsc.Api.Client;
+
+/// <summary>
+/// HTTP client for the estimate routes (<c>api/v1/estimate</c>,
+/// served by <c>EstimateApiController</c>). Follows the same
+/// DTO↔path mapper shape as <see cref="BillingApiClient"/>: all
+/// transport concerns (base URL, JSON, Bearer auth, silent refresh
+/// on 401) are delegated to <see cref="IYavscApiClient"/>.
+/// </summary>
+public sealed class EstimateApiClient
+{
+    private const string PathPrefix = "estimate";
+
+    private readonly IYavscApiClient _api;
+    private readonly Func<string> _businessBaseAddress;
+
+    public EstimateApiClient(IYavscApiClient api, string businessBaseAddress)
+        : this(api, () => businessBaseAddress)
+    {
+    }
+
+    public EstimateApiClient(IYavscApiClient api, Func<string> businessBaseAddress)
+    {
+        _api = api ?? throw new ArgumentNullException(nameof(api));
+        _businessBaseAddress = businessBaseAddress ?? throw new ArgumentNullException(nameof(businessBaseAddress));
+
+        // Validate initial value early to fail fast on invalid setup.
+        _ = ResolveBusinessBaseAddress();
+    }
+
+    /// <summary>
+    /// Lists the estimates of the given owner; when <paramref name="ownerId"/>
+    /// is null, the server falls back to the current user.
+    /// </summary>
+    public Task<List<EstimateDto>> GetEstimatesAsync(string? ownerId = null, CancellationToken ct = default)
+    {
+        var path = string.IsNullOrWhiteSpace(ownerId)
+            ? PathPrefix
+            : $"{PathPrefix}?ownerId={Uri.EscapeDataString(ownerId)}";
+
+        return _api.CallAsync<List<EstimateDto>>(HttpMethod.Get, Absolute(path), ct: ct);
+    }
+
+    public Task<EstimateDto> GetEstimateAsync(long id, CancellationToken ct = default)
+    {
+        if (id <= 0)
+            throw new ArgumentOutOfRangeException(nameof(id));
+
+        return _api.CallAsync<EstimateDto>(HttpMethod.Get, Absolute($"{PathPrefix}/{id}"), ct: ct);
+    }
+
+    /// <summary>
+    /// Creates an estimate. When <see cref="EstimateDto.CommandId"/> is set,
+    /// the server also stamps the linked command as validated.
+    /// </summary>
+    public async Task<EstimateCreatedDto> CreateAsync(EstimateDto estimate, CancellationToken ct = default)
+    {
+        if (estimate is null)
+            throw new ArgumentNullException(nameof(estimate));
+
+        var created = await _api.CallAsync<EstimateCreatedDto>(
+            HttpMethod.Post,
+            Absolute(PathPrefix),
+            body: estimate,
+            ct: ct).ConfigureAwait(false);
+
+        return created ?? new EstimateCreatedDto();
+    }
+
+    public Task UpdateAsync(long id, EstimateDto estimate, CancellationToken ct = default)
+    {
+        if (id <= 0)
+            throw new ArgumentOutOfRangeException(nameof(id));
+        if (estimate is null)
+            throw new ArgumentNullException(nameof(estimate));
+
+        estimate.Id = id;
+
+        return _api.CallAsync(
+            HttpMethod.Put,
+            Absolute($"{PathPrefix}/{id}"),
+            body: estimate,
+            ct: ct);
+    }
+
+    public Task DeleteAsync(long id, CancellationToken ct = default)
+    {
+        if (id <= 0)
+            throw new ArgumentOutOfRangeException(nameof(id));
+
+        return _api.CallAsync(HttpMethod.Delete, Absolute($"{PathPrefix}/{id}"), ct: ct);
+    }
+
+    private string Absolute(string relativePath) => new Uri(ResolveBusinessBaseAddress(), relativePath).ToString();
+
+    private Uri ResolveBusinessBaseAddress()
+    {
+        var raw = _businessBaseAddress();
+        if (string.IsNullOrWhiteSpace(raw))
+            throw new InvalidOperationException("Business base address is required.");
+
+        return new Uri(raw, UriKind.Absolute);
+    }
+}
diff --git a/src/Yavsc.Api.Test/EstimateApiControllerTests.cs b/src/Yavsc.Api.Test/EstimateApiControllerTests.cs
new file mode 100644
index 000000000..10a9c000b
--- /dev/null
+++ b/src/Yavsc.Api.Test/EstimateApiControllerTests.cs
@@ -0,0 +1,209 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using System.Text.Json;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Yavsc.Api.Test.Fixtures;
+using Yavsc.Models;
+using Yavsc.Models.Billing;
+using Yavsc.Models.Workflow;
+using Yavsc.Tests.Shared;
+
+namespace Yavsc.Api.Test;
+
+[Collection("Yavsc Api")]
+public sealed class EstimateApiControllerTests : IClassFixture<ApiWebServerFixture>
+{
+    private readonly ApiWebServerFixture _fixture;
+
+    public EstimateApiControllerTests(ApiWebServerFixture fixture)
+    {
+        _fixture = fixture;
+    }
+
+    private HttpClient NewClient(string subject = "alice", string scope = "api")
+    {
+        var handler = new HttpClientHandler
+        {
+            ServerCertificateCustomValidationCallback = (_, _, _, _) => true
+        };
+
+        var http = new HttpClient(handler)
+        {
+            BaseAddress = new Uri(_fixture.BaseAddress)
+        };
+
+        http.DefaultRequestHeaders.Authorization =
+            new AuthenticationHeaderValue("Bearer", TestTokenIssuer.Issue(subject, scope));
+
+        return http;
+    }
+
+    /// <summary>
+    /// Seed a provider (alice) and a client (bob) with a pending
+    /// <see cref="RdvQuery"/> from bob to alice, and return the
+    /// command id.
+    /// </summary>
+    private long SeedPendingCommand()
+    {
+        _fixture.ResetAndSeedActivityGraph();
+
+        using var scope = _fixture.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+        var location = db.Locations.Single();
+
+        var query = new RdvQuery
+        {
+            ActivityCode = "dev",
+            ClientId = "bob",
+            PerformerId = "alice",
+            Consent = true,
+            UserCreated = "bob",
+            UserModified = "bob",
+            DateCreated = DateTime.UtcNow.AddMinutes(-10),
+            DateModified = DateTime.UtcNow.AddMinutes(-10),
+            EventDate = DateTime.UtcNow.AddDays(1),
+            Location = location,
+            Reason = "Demande de devis",
+            Status = QueryStatus.InProgress,
+            Description = "Demande en attente de devis",
+        };
+        db.RdvQueries.Add(query);
+        db.SaveChanges();
+
+        return query.Id;
+    }
+
+    private static object NewEstimatePayload(long? commandId, string clientId, string? ownerId = null)
+        => new
+        {
+            CommandId = commandId,
+            ClientId = clientId,
+            OwnerId = ownerId,
+            CommandType = BillingCodes.Rdv,
+            Title = "Devis prestation",
+            Description = "Devis détaillé",
+            AttachedFiles = Array.Empty<string>(),
+            AttachedGraphics = Array.Empty<string>(),
+            Bill = new[]
+            {
+                new { Name = "Prestation", Description = "Prestation de base", Count = 1, UnitaryCost = 120m, Currency = "EUR" },
+                new { Name = "Remise", Description = "Remise fidélité", Count = 1, UnitaryCost = -20m, Currency = "EUR" },
+            },
+        };
+
+    [Fact]
+    public async Task PostEstimate_creates_the_estimate_and_validates_the_linked_command()
+    {
+        var commandId = SeedPendingCommand();
+        using var http = NewClient("alice");
+
+        var response = await http.PostAsJsonAsync(
+            "/api/v1/estimate",
+            NewEstimatePayload(commandId, clientId: "bob", ownerId: "alice"),
+            TestContext.Current.CancellationToken);
+        var body = await response.Content.ReadAsStringAsync(TestContext.Current.CancellationToken);
+
+        Assert.True(response.StatusCode == HttpStatusCode.OK, $"Unexpected status {(int)response.StatusCode} ({response.StatusCode}): {body}");
+
+        using var doc = JsonDocument.Parse(body);
+        var estimateId = doc.RootElement.GetProperty("id").GetInt64();
+        Assert.True(estimateId > 0);
+        Assert.Equal(2, doc.RootElement.GetProperty("bill").GetArrayLength());
+
+        using var scope = _fixture.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+
+        var estimate = db.Estimates.Include(e => e.Bill).Single(e => e.Id == estimateId);
+        Assert.Equal("alice", estimate.OwnerId);
+        Assert.Equal("bob", estimate.ClientId);
+        Assert.Equal(commandId, estimate.CommandId);
+        Assert.Equal(BillingCodes.Rdv, estimate.CommandType);
+        Assert.Equal(2, estimate.Bill.Count);
+        Assert.Contains(estimate.Bill, line => line.UnitaryCost == -20m);
+
+        // PostEstimate stamps the linked command as validated.
+        var query = db.RdvQueries.Single(q => q.Id == commandId);
+        Assert.NotNull(query.ValidationDate);
+    }
+
+    [Fact]
+    public async Task PostEstimate_without_command_creates_a_standalone_estimate()
+    {
+        _fixture.ResetAndSeedActivityGraph();
+        using var http = NewClient("alice");
+
+        var response = await http.PostAsJsonAsync(
+            "/api/v1/estimate",
+            NewEstimatePayload(commandId: null, clientId: "bob"),
+            TestContext.Current.CancellationToken);
+        var body = await response.Content.ReadAsStringAsync(TestContext.Current.CancellationToken);
+
+        Assert.True(response.StatusCode == HttpStatusCode.OK, $"Unexpected status {(int)response.StatusCode} ({response.StatusCode}): {body}");
+
+        using var doc = JsonDocument.Parse(body);
+        var estimateId = doc.RootElement.GetProperty("id").GetInt64();
+
+        using var scope = _fixture.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+        var estimate = db.Estimates.Single(e => e.Id == estimateId);
+        Assert.Null(estimate.CommandId);
+        Assert.Equal("alice", estimate.OwnerId);
+    }
+
+    [Fact]
+    public async Task PostEstimate_for_another_owner_is_rejected()
+    {
+        _fixture.ResetAndSeedActivityGraph();
+        using var http = NewClient("alice");
+
+        var response = await http.PostAsJsonAsync(
+            "/api/v1/estimate",
+            NewEstimatePayload(commandId: null, clientId: "bob", ownerId: "bob"),
+            TestContext.Current.CancellationToken);
+
+        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
+
+        using var scope = _fixture.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+        Assert.Empty(db.Estimates);
+    }
+
+    [Fact]
+    public async Task PostEstimate_with_an_unknown_command_id_is_rejected()
+    {
+        _fixture.ResetAndSeedActivityGraph();
+        using var http = NewClient("alice");
+
+        var response = await http.PostAsJsonAsync(
+            "/api/v1/estimate",
+            NewEstimatePayload(commandId: 999999, clientId: "bob"),
+            TestContext.Current.CancellationToken);
+
+        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
+
+        using var scope = _fixture.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+        Assert.Empty(db.Estimates);
+    }
+
+    [Fact]
+    public async Task PostEstimate_without_token_is_unauthorized()
+    {
+        _fixture.ResetAndSeedActivityGraph();
+
+        var handler = new HttpClientHandler
+        {
+            ServerCertificateCustomValidationCallback = (_, _, _, _) => true
+        };
+        using var http = new HttpClient(handler) { BaseAddress = new Uri(_fixture.BaseAddress) };
+
+        var response = await http.PostAsJsonAsync(
+            "/api/v1/estimate",
+            NewEstimatePayload(commandId: null, clientId: "bob"),
+            TestContext.Current.CancellationToken);
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+}
diff --git a/src/Yavsc.Api/Controllers/Business/EstimateApiController.cs b/src/Yavsc.Api/Controllers/Business/EstimateApiController.cs
index 210dd2251..94a9b14dd 100644
--- a/src/Yavsc.Api/Controllers/Business/EstimateApiController.cs
+++ b/src/Yavsc.Api/Controllers/Business/EstimateApiController.cs
@@ -77,7 +77,7 @@ namespace Yavsc.Controllers
             {
                 return BadRequest();
             }
-            var uid = User.FindFirstValue(ClaimTypes.NameIdentifier);
+            var uid = User.GetUserId();
             if (!User.IsInRole(Constants.AdminGroupName))
             {
                 if (uid != estimate.OwnerId)
@@ -111,7 +111,7 @@ namespace Yavsc.Controllers
         [HttpPost, Produces("application/json")]
         public IActionResult PostEstimate([FromBody] Estimate estimate)
         {
-            var uid = User.FindFirstValue(ClaimTypes.NameIdentifier);
+            var uid = User.GetUserId();
             if (estimate.OwnerId == null) estimate.OwnerId = uid;
 
             if (!User.IsInRole(Constants.AdminGroupName))
@@ -183,7 +183,7 @@ namespace Yavsc.Controllers
             {
                 return NotFound();
             }
-            var uid = User.FindFirstValue(ClaimTypes.NameIdentifier);
+            var uid = User.GetUserId();
             if (!User.IsInRole(Constants.AdminGroupName))
             {
                 if (uid != estimate.OwnerId)
diff --git a/src/Yavsc.Server/Models/Billing/Estimate.cs b/src/Yavsc.Server/Models/Billing/Estimate.cs
index c2912b25a..74680e7b7 100644
--- a/src/Yavsc.Server/Models/Billing/Estimate.cs
+++ b/src/Yavsc.Server/Models/Billing/Estimate.cs
@@ -2,6 +2,7 @@
 
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
+using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 
 namespace Yavsc.Models.Billing
 {
@@ -20,7 +21,7 @@ namespace Yavsc.Models.Billing
         /// it will result in a new estimate template
         /// </summary>
         /// <returns></returns>
-        [ForeignKey("CommandId"),JsonIgnore]
+        [ForeignKey("CommandId"),JsonIgnore,ValidateNever]
         public NominativeServiceCommand? Query { get; set; }
         public string Description { get; set; }
         public string Title { get; set; }
@@ -57,14 +58,15 @@ namespace Yavsc.Models.Billing
             set { AttachedFiles = value.Split(':').ToList(); }
         }
 
+        [ValidateNever]
         public string OwnerId { get; set; }
 
-        [ForeignKey("OwnerId"),JsonIgnore]
+        [ForeignKey("OwnerId"),JsonIgnore,ValidateNever]
         public virtual PerformerProfile Owner { get; set; }
 
         [Required]
         public string ClientId { get; set; }
-        [ForeignKey("ClientId"),JsonIgnore]
+        [ForeignKey("ClientId"),JsonIgnore,ValidateNever]
         public virtual ApplicationUser Client { get; set; }
 
         [Required]