policy+tui: raise coverage above target (M1)

policy 66% -> 94.7%: TestLoad exercises the previously-untested Load path —
empty/missing path fall back to Default, valid YAML parses onto the Default base
(absent fields keep their default; overrides apply), malformed YAML and a
non-regular file (directory) both error. Documents that a map override entry is
replaced wholesale by yaml.v3 (Evaluate re-merges defaults, so it's harmless).

tui 57% -> 87.8%: cover Init, the "o" open branches (URL vs none), "s" skip and
prev/next boundary guards, non-key messages, enter-at-last-item, esc/ctrl+c
quit, openURL's command, and Run's headless empty-list path. The residual is the
TTY-only tea.Program.Run() launch, not unit-testable headless.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/tui/guide_test.go

@@ -95,3 +95,101 @@ func TestEmptyModelView(t *testing.T) {
 		t.Errorf("empty view = %q", got)
 	}
 }
+
+func TestInitNoCmd(t *testing.T) {
+	if cmd := sampleModel().Init(); cmd != nil {
+		t.Errorf("Init returned a command, want nil")
+	}
+}
+
+// TestUpdateIgnoresNonKeyMsg proves a non-keyboard message leaves the model
+// unchanged (the walk-through only responds to key presses).
+func TestUpdateIgnoresNonKeyMsg(t *testing.T) {
+	m := sampleModel()
+	nm, cmd := m.Update(tea.WindowSizeMsg{Width: 80, Height: 24})
+	if cmd != nil {
+		t.Error("non-key msg produced a command")
+	}
+	if nm.(Model).cur != 0 {
+		t.Error("non-key msg moved the cursor")
+	}
+}
+
+// TestOpenBranches covers "o": on an item with a URL it emits an open command; on an
+// item with no rotation page it does nothing.
+func TestOpenBranches(t *testing.T) {
+	m := sampleModel() // item0 (git) has a URL; item1 (ssh) has none
+	_, cmd := m.Update(key("o"))
+	if cmd == nil {
+		t.Error("o on an item with a URL returned no command")
+	}
+	nm, _ := m.Update(key("n")) // advance to the URL-less ssh item
+	m = nm.(Model)
+	if _, cmd := m.Update(key("o")); cmd != nil {
+		t.Error("o on an item with no URL returned a command")
+	}
+}
+
+// TestSkipAndBoundaries covers "s" (skip → next) and the prev/next boundary guards.
+func TestSkipAndBoundaries(t *testing.T) {
+	m := sampleModel()
+	// prev at the first item is a no-op.
+	nm, _ := m.Update(key("k"))
+	if nm.(Model).cur != 0 {
+		t.Error("k at index 0 moved the cursor")
+	}
+	m = nm.(Model)
+	// skip advances.
+	nm, _ = m.Update(key("s"))
+	m = nm.(Model)
+	if m.cur != 1 {
+		t.Errorf("s did not advance, cur=%d", m.cur)
+	}
+	// skip at the last item is a no-op.
+	nm, _ = m.Update(key("s"))
+	if nm.(Model).cur != 1 {
+		t.Error("s past end moved the cursor")
+	}
+}
+
+// TestEnterAtLastItemStays proves enter marks the last item done without advancing
+// past the end of the list.
+func TestEnterAtLastItemStays(t *testing.T) {
+	m := sampleModel()
+	nm, _ := m.Update(key("n")) // to last item (index 1)
+	m = nm.(Model)
+	nm, _ = m.Update(key("enter"))
+	m = nm.(Model)
+	if !m.done[1] {
+		t.Error("enter did not mark the last item done")
+	}
+	if m.cur != 1 {
+		t.Errorf("enter advanced past the last item, cur=%d", m.cur)
+	}
+}
+
+// TestQuitVariants covers the esc and ctrl+c quit keys alongside q.
+func TestQuitVariants(t *testing.T) {
+	for _, k := range []tea.KeyMsg{{Type: tea.KeyEsc}, {Type: tea.KeyCtrlC}} {
+		nm, cmd := sampleModel().Update(k)
+		if !nm.(Model).quit || cmd == nil {
+			t.Errorf("%v did not quit", k)
+		}
+	}
+}
+
+// TestOpenURLCmd invokes the command returned by openURL: it is best-effort (the
+// launcher may be absent on a headless host) and must return a nil message.
+func TestOpenURLCmd(t *testing.T) {
+	if msg := openURL("https://example.com")(); msg != nil {
+		t.Errorf("openURL cmd returned %v, want nil", msg)
+	}
+}
+
+// TestRunEmptyReturnsNil covers Run's headless-safe path: no items → prints a notice
+// and returns without launching the (TTY-requiring) Bubble Tea program.
+func TestRunEmptyReturnsNil(t *testing.T) {
+	if err := Run(nil); err != nil {
+		t.Errorf("Run(nil) = %v, want nil", err)
+	}
+}