Chat backgrounds in the box, undo for the notes assistant, and richer…

CHANGELOG.md

@@ -6,7 +6,62 @@ recorded by the `MandoCode` submodule.
 
 ## [Unreleased]
 
+### Changed
+- **Assistant text always starts on its own line.** Inserting a reply at the cursor used to glue it
+  onto the tail of whatever line you were mid-way through. It now opens a new line first — unless
+  the cursor already sits at the start of one, so an empty note doesn't gain a blank first line.
+  Replacing a highlighted selection is unchanged: there you aimed at a specific span, and pushing
+  the replacement onto its own line would orphan the rest of that line.
+- **The snapshot offer now reads as a card floating over the chat.** It was painted with the same
+  panel shade as the docked chrome, which sits within a few points of the transcript background in
+  most themes (Visual Studio Dark is `#252526` on `#1E1E1E`), so it blended into the conversation.
+  Both stages — the thin bar and the full name + model picker — now use a new raised surface plus an
+  accent edge. The shade is derived per theme from that theme's own accent rather than hand-picked,
+  so it carries the theme's character (grayscale in E-Ink Paper, navy in W98, phosphor green in
+  Phosphor Fwog) and new themes get one automatically. The tint eases off on a theme whose text
+  contrast can't afford it — Solarized Light, which already sat below AA on its own panel — and is
+  skipped entirely on a theme whose panel already reads as raised, which keeps W98's card the
+  period-correct white dialog on the silver desktop.
+
+### Fixed
+- **W98 chat prompts are readable again.** Your own prompts rendered in the theme's gold, which
+  resolves to a dark mustard `#806000` — 3.21:1 on a silver window, under the accessibility floor
+  and hard going for anyone with less-than-perfect sight. W98 prompts now use black window text
+  (11.5:1), which is the era-correct answer anyway; the silver bevelled frame already marks whose
+  turn it is. The "Show more" toggle on a clamped prompt got the same treatment: it sits on the teal
+  desktop rather than in the window, where the dim gray it used was 1.44:1 — effectively invisible —
+  and is now white underlined at 4.77:1. Other themes are untouched.
+
 ### Added
+- **Undo for the notes assistant.** A gold undo arrow appears in the note header after the assistant
+  inserts or replaces text, putting the note back exactly as it was. Ctrl+Z can't do this job —
+  assigning the editor's text resets the TextBox's own undo history, so the one edit you *didn't*
+  type by hand was the one the control couldn't reverse, and a Replace could take a whole note with
+  it. The offer covers the assistant's last edit only and retires the moment you type, since
+  restoring the earlier buffer would otherwise discard whatever you'd written on top of it.
+- **Chat backgrounds included in the box.** Settings → Appearance now offers a gallery of three
+  backgrounds that ship with MandoCode — **Golden Gate**, **Sequoia Trail**, and **Pismo Beach** —
+  so a fresh install has something to pick without hunting for a file. Click a tile to use it, click it again to turn it off; the active one is ringed and
+  named. Choosing your own image works exactly as before, and the two are interchangeable — a
+  tile is just a starting point, not a mode. The gallery is read from the release's
+  `Assets/images/backgrounds` folder at startup rather than listed in code, so a future release
+  adds one by dropping the file in. A **fresh install now opens on "Golden Gate"** at the usual 30%
+  opacity instead of a bare theme — first launch only, so nobody who has already set (or cleared) a
+  background is re-skinned by an update.
+- **One-click snapshot from the tab header.** A camera button joins the folder and explorer icons
+  at the right of each agent's header, taking the same snapshot offer that lived two clicks deep
+  in the tab's "…" menu (which stays). It sits with the header's other *actions* rather than
+  beside the model label it captures, so it keeps a fixed position instead of sliding whenever
+  the model name changes length. On an empty conversation it answers with the usual "Nothing to
+  snapshot" chip rather than presenting a dead button.
+- **History cards quote the agent's last reply.** A card showed the opening prompt and the last
+  thing you typed; it now adds the last thing the agent *said*, which is usually what you
+  actually remember a conversation by. The reply is flattened out of markdown (code fences,
+  headings, bullets and tables dropped; link text kept) and clipped to its first couple of
+  sentences, so the card doesn't grow — the opening line gives up a third row of wrapping to pay
+  for it. The two closing quotes are now labeled **you** and **reply** so it's clear which voice
+  is which. Conversations archived before this fill in on the first History open, alongside the
+  existing last-message backfill (one file read for both).
 - **Agent callsigns.** A Settings → Behavior toggle (app-wide) names new agents from a
   curated 500+ pool of handles — construct-crew, phreak, and cypher energy ("Morphy",
   "Crunch", "Blazor", "Kaos") — drawn from a shuffled deck that doesn't repeat until it runs

src/MandoCode.Desktop.Tests/BuiltInBackgroundsTests.cs

@@ -0,0 +1,104 @@
+using MandoCode.Desktop.Services;
+using Xunit;
+
+namespace MandoCode.Desktop.Tests;
+
+/// <summary>
+/// The bundled-background gallery is discovered from a folder rather than declared in code, so the
+/// file-naming convention IS the contract — these pin the rules documented in
+/// Assets/images/backgrounds/README.md, which is what a future release adds images against.
+/// </summary>
+public class BuiltInBackgroundsTests : IDisposable
+{
+    private readonly string _folder = Path.Combine(
+        Path.GetTempPath(), "mandocode-bg-tests-" + Guid.NewGuid().ToString("N"));
+
+    public BuiltInBackgroundsTests() => Directory.CreateDirectory(_folder);
+
+    public void Dispose()
+    {
+        try { Directory.Delete(_folder, recursive: true); } catch { }
+    }
+
+    private void Add(string fileName) => File.WriteAllText(Path.Combine(_folder, fileName), "x");
+
+    // ---- display names ---------------------------------------------------------------
+
+    [Theory]
+    [InlineData("01-nebula-drift.jpg", "Nebula Drift")]
+    [InlineData("02-violet-haze.png", "Violet Haze")]
+    [InlineData("10_deep_space.webp", "Deep Space")]
+    [InlineData("aurora.jpg", "Aurora")]
+    [InlineData("two words.png", "Two Words")]
+    public void DisplayNameFor_strips_the_ordering_prefix_and_titlecases(string file, string expected)
+        => Assert.Equal(expected, BuiltInBackgrounds.DisplayNameFor(file));
+
+    [Fact]
+    public void DisplayNameFor_keeps_a_leading_number_that_is_part_of_the_name()
+    {
+        // No separator after the digits, so "1999" is the name — not an ordering prefix.
+        Assert.Equal("1999 Skyline", BuiltInBackgrounds.DisplayNameFor("1999 skyline.jpg"));
+        // A prefix with nothing after it must not clip the whole name away.
+        Assert.Equal("01", BuiltInBackgrounds.DisplayNameFor("01.jpg"));
+    }
+
+    // ---- discovery -------------------------------------------------------------------
+
+    [Fact]
+    public void DiscoverIn_returns_empty_for_a_missing_folder()
+        => Assert.Empty(BuiltInBackgrounds.DiscoverIn(Path.Combine(_folder, "nope")));
+
+    [Fact]
+    public void DiscoverIn_returns_empty_when_the_folder_has_no_images()
+    {
+        Add("README.md");
+        Assert.Empty(BuiltInBackgrounds.DiscoverIn(_folder));
+    }
+
+    [Fact]
+    public void DiscoverIn_orders_by_file_name_so_the_numeric_prefix_controls_the_gallery()
+    {
+        Add("03-third.jpg");
+        Add("01-first.jpg");
+        Add("02-second.jpg");
+
+        Assert.Equal(
+            new[] { "First", "Second", "Third" },
+            BuiltInBackgrounds.DiscoverIn(_folder).Select(b => b.DisplayName));
+    }
+
+    [Fact]
+    public void DiscoverIn_takes_only_decodable_image_extensions()
+    {
+        Add("01-keep.jpg");
+        Add("02-keep.jpeg");
+        Add("03-keep.png");
+        Add("04-keep.webp");
+        Add("05-skip.txt");
+        Add("06-skip.bmp");     // the picker accepts it; BitmapImage thumbnails don't
+        Add("README.md");
+
+        var found = BuiltInBackgrounds.DiscoverIn(_folder);
+        Assert.Equal(4, found.Count);
+        Assert.All(found, b => Assert.StartsWith("Keep", b.DisplayName));
+    }
+
+    [Fact]
+    public void DiscoverIn_is_case_insensitive_about_extensions()
+    {
+        Add("01-shouty.JPG");
+        Assert.Single(BuiltInBackgrounds.DiscoverIn(_folder));
+    }
+
+    [Fact]
+    public void DiscoverIn_carries_the_file_name_as_the_durable_identity()
+    {
+        Add("01-nebula-drift.jpg");
+        var only = Assert.Single(BuiltInBackgrounds.DiscoverIn(_folder));
+
+        // The FILE NAME is what's persisted to mark the active tile — not the display name, which
+        // is derived and would change if the labeling rules ever did.
+        Assert.Equal("01-nebula-drift.jpg", only.FileName);
+        Assert.Equal(Path.Combine(_folder, "01-nebula-drift.jpg"), only.FullPath);
+    }
+}

src/MandoCode.Desktop.Tests/CardPreviewTests.cs

@@ -0,0 +1,132 @@
+using MandoCode.Desktop.Services;
+using Xunit;
+
+namespace MandoCode.Desktop.Tests;
+
+public class CardPreviewTests
+{
+    // ---- Trim: the quoted user turns -------------------------------------------------
+
+    [Fact]
+    public void Trim_returns_null_for_nothing_to_show()
+    {
+        Assert.Null(CardPreview.Trim(null));
+        Assert.Null(CardPreview.Trim(""));
+        Assert.Null(CardPreview.Trim("   \n  "));
+    }
+
+    [Fact]
+    public void Trim_keeps_a_short_message_whole_and_unellipsised()
+        => Assert.Equal("checkout main and pull latest", CardPreview.Trim("  checkout main and pull latest  "));
+
+    [Fact]
+    public void Trim_caps_a_long_message_with_an_ellipsis()
+    {
+        var clipped = CardPreview.Trim(new string('x', CardPreview.UserChars + 50));
+        Assert.Equal(CardPreview.UserChars + 1, clipped!.Length);   // the cap plus the ellipsis
+        Assert.EndsWith("…", clipped);
+    }
+
+    // ---- ClipReply: the agent's answer ----------------------------------------------
+
+    [Fact]
+    public void ClipReply_returns_null_when_there_is_no_reply()
+    {
+        Assert.Null(CardPreview.ClipReply(null));
+        Assert.Null(CardPreview.ClipReply("  "));
+    }
+
+    [Fact]
+    public void ClipReply_keeps_the_first_two_sentences_and_drops_the_rest()
+        => Assert.Equal(
+            "Already on main. The pull failed.",
+            CardPreview.ClipReply("Already on main. The pull failed. Git could not authenticate. Try gh."));
+
+    [Fact]
+    public void ClipReply_keeps_a_one_sentence_reply_whole()
+        => Assert.Equal("Done — the branch is clean.", CardPreview.ClipReply("Done — the branch is clean."));
+
+    [Fact]
+    public void ClipReply_keeps_a_reply_with_no_terminator_at_all()
+        => Assert.Equal("no trailing period here", CardPreview.ClipReply("no trailing period here"));
+
+    [Fact]
+    public void ClipReply_collapses_paragraphs_into_one_line()
+        => Assert.Equal(
+            "First line. Second line.",
+            CardPreview.ClipReply("First line.\n\n   Second line.\n"));
+
+    [Fact]
+    public void ClipReply_drops_fenced_code_blocks()
+        => Assert.Equal(
+            "Here is the fix.",
+            CardPreview.ClipReply("Here is the fix.\n\n```csharp\nvar x = 1;   // not card material\n```\n"));
+
+    [Fact]
+    public void ClipReply_drops_tilde_fences_too()
+        => Assert.Equal("Ran it.", CardPreview.ClipReply("Ran it.\n~~~\ngit status\n~~~"));
+
+    [Fact]
+    public void ClipReply_returns_null_when_only_code_remains()
+        => Assert.Null(CardPreview.ClipReply("```\ngit push --force\n```"));
+
+    [Fact]
+    public void ClipReply_strips_headings_quotes_and_bullets()
+        => Assert.Equal(
+            "Summary Pulled main. Synced the submodule.",
+            CardPreview.ClipReply("## Summary\n\n- Pulled main.\n- Synced the submodule."));
+
+    [Fact]
+    public void ClipReply_strips_numbered_items_but_keeps_prose_that_starts_with_a_digit()
+    {
+        Assert.Equal("Fetch. Merge.", CardPreview.ClipReply("1. Fetch.\n2) Merge."));
+        Assert.Equal("27 files changed.", CardPreview.ClipReply("27 files changed."));
+    }
+
+    [Fact]
+    public void ClipReply_strips_task_list_checkboxes()
+        => Assert.Equal("done thing", CardPreview.ClipReply("- [x] done thing"));
+
+    [Fact]
+    public void ClipReply_strips_emphasis_and_code_spans_but_keeps_underscores()
+        => Assert.Equal(
+            "The LastMessage field on session_archive is set.",
+            CardPreview.ClipReply("The **LastMessage** field on `session_archive` is set."));
+
+    [Fact]
+    public void ClipReply_keeps_link_text_and_drops_the_target()
+        => Assert.Equal(
+            "See MainWindow.xaml for the template.",
+            CardPreview.ClipReply("See [MainWindow.xaml](src/MandoCode.Desktop/MainWindow.xaml) for the template."));
+
+    [Fact]
+    public void ClipReply_drops_table_separator_rows()
+        => Assert.Equal(
+            "Results: | file | lines |",
+            CardPreview.ClipReply("Results:\n\n| file | lines |\n|------|-------|"));
+
+    [Fact]
+    public void ClipReply_does_not_split_on_decimals_or_file_names()
+        => Assert.Equal(
+            "Bumped to v1.2 in MainWindow.xaml.cs today. Second sentence.",
+            CardPreview.ClipReply("Bumped to v1.2 in MainWindow.xaml.cs today. Second sentence. Third."));
+
+    [Fact]
+    public void ClipReply_treats_a_terminator_cluster_as_one_sentence_end()
+        => Assert.Equal("Wait, what?! It worked.", CardPreview.ClipReply("Wait, what?! It worked. Really."));
+
+    [Fact]
+    public void ClipReply_does_not_split_on_a_short_abbreviation()
+        => Assert.Equal(
+            "Use gh, e.g. gh auth login, to sign in. Then pull.",
+            CardPreview.ClipReply("Use gh, e.g. gh auth login, to sign in. Then pull. And build."));
+
+    [Fact]
+    public void ClipReply_hard_caps_a_long_two_sentence_reply()
+    {
+        var wordy = new string('a', 200) + ". " + new string('b', 200) + ".";
+        var clipped = CardPreview.ClipReply(wordy);
+        Assert.Equal(CardPreview.ReplyChars + 1, clipped!.Length);   // the cap plus the ellipsis
+        Assert.EndsWith("…", clipped);
+    }
+}

src/MandoCode.Desktop.Tests/MandoCode.Desktop.Tests.csproj

@@ -38,6 +38,13 @@
     <Compile Include="..\MandoCode.Desktop\Services\ContextSnapshot.cs" Link="src\ContextSnapshot.cs" />
     <Compile Include="..\MandoCode.Desktop\Services\SnapshotNaming.cs" Link="src\SnapshotNaming.cs" />
     <Compile Include="..\MandoCode.Desktop\Services\SessionArchiveStore.cs" Link="src\SessionArchiveStore.cs" />
+    <!-- The History card's quote-clipping rules: capping a user turn, and flattening the agent's
+         markdown reply down to a couple of sentences. Pure string work, which is exactly why it
+         lives in Services rather than in the panel's code-behind. -->
+    <Compile Include="..\MandoCode.Desktop\Services\CardPreview.cs" Link="src\CardPreview.cs" />
+    <!-- The bundled-background gallery. Discovered from a folder rather than declared in code, so
+         the file-naming convention is a real contract worth pinning; pure System.IO, no WinUI. -->
+    <Compile Include="..\MandoCode.Desktop\Services\BuiltInBackgrounds.cs" Link="src\BuiltInBackgrounds.cs" />
     <Compile Include="..\MandoCode.Desktop\Services\TranscriptJournal.cs" Link="src\TranscriptJournal.cs" />
     <Compile Include="..\MandoCode.Desktop\Services\ConversationLog.cs" Link="src\ConversationLog.cs" />
     <!-- History's full-text matching + snippet extraction. Pure (text in, match out); the file reads

src/MandoCode.Desktop.Tests/NoteTextTests.cs

@@ -85,4 +85,44 @@ public void A_round_trip_through_the_editor_form_preserves_the_file()
             Assert.Equal(original, NoteText.ToFileText(editorForm, newline));
         }
     }
+
+    // ---- LeadIn: assistant output always starts on its own line ----------------------
+
+    [Fact]
+    public void LeadIn_adds_a_newline_when_the_caret_sits_mid_line()
+    {
+        // The case this exists for: a reply landing on the tail of the line you were writing.
+        Assert.Equal("\n", NoteText.LeadIn("shopping list", 13));
+        Assert.Equal("\n", NoteText.LeadIn("one\rtwo", 7));
+    }
+
+    [Fact]
+    public void LeadIn_adds_nothing_at_the_very_start_of_a_note()
+    {
+        Assert.Equal("", NoteText.LeadIn("", 0));
+        Assert.Equal("", NoteText.LeadIn("already here", 0));
+    }
+
+    [Theory]
+    [InlineData("done\r", 5)]      // editor form — WinUI holds newlines as bare CR
+    [InlineData("done\n", 5)]      // file form, in case a buffer ever carries LF
+    [InlineData("done\r\n", 6)]
+    public void LeadIn_adds_nothing_when_the_caret_already_starts_a_line(string body, int at)
+        => Assert.Equal("", NoteText.LeadIn(body, at));
+
+    [Fact]
+    public void LeadIn_does_not_double_up_on_a_blank_line()
+    {
+        // Caret after a blank line: there's already a line to write on, so forcing another newline
+        // would push assistant output down with a stray gap above it every time.
+        Assert.Equal("", NoteText.LeadIn("notes\r\r", 7));
+    }
+
+    [Fact]
+    public void LeadIn_tolerates_a_caret_past_the_end()
+    {
+        // Defensive: the caller clamps, but a LeadIn that threw would take the insert down with it.
+        Assert.Equal("\n", NoteText.LeadIn("abc", 99));
+        Assert.Equal("", NoteText.LeadIn("", 99));
+    }
 }

src/MandoCode.Desktop/App.xaml

@@ -36,6 +36,14 @@
             <SolidColorBrush x:Key="MandoTextBrush" Color="{StaticResource MandoTextColor}" />
             <SolidColorBrush x:Key="MandoDimBrush" Color="{StaticResource MandoDimColor}" />
 
+            <!-- Raised surface, for cards that FLOAT over the transcript and must not read as
+                 more transcript. Panel sits only a few points from Background in most themes,
+                 so a floating card painted with Panel disappears. Derived per theme from that
+                 theme's own accent — see ThemeManager.Raised; this literal is the Mando Dark
+                 value, used only until Initialize applies the saved theme. -->
+            <Color x:Key="MandoRaisedColor">#3E2753</Color>
+            <SolidColorBrush x:Key="MandoRaisedBrush" Color="{StaticResource MandoRaisedColor}" />
+
             <!-- Replace the user's Windows accent color with MandoCode purple so
                  accent buttons, toggle switches, sliders, and selection highlights
                  match the brand on every machine -->