feat(ui): custom substring/AND filter for station list

Replace default fuzzy filter with substring matching where multi-word
queries require all words to appear. Fix auto-filter typing to properly
batch returned commands instead of discarding them. Update tests to
drive command loops and verify exact substring matches.

internal/ui/ui.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"strings"
 
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/bubbles/list"
@@ -88,6 +89,37 @@ func NewApp(initial []radio.Station) *App {
 	l.SetFilteringEnabled(true)
 	l.Styles.Title = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("63"))
 
+	// Use a custom substring/AND filter instead of the default fuzzy (which matches
+	// any combination of individual letters, e.g. "WFMT" matching stations with W or F or M or T).
+	// This makes "/WFMT" find stations containing the substring "wfmt" (case-insensitive),
+	// and multi-word searches require all words to appear somewhere in the target.
+	l.Filter = func(term string, targets []string) []list.Rank {
+		term = strings.TrimSpace(term)
+		if term == "" {
+			ranks := make([]list.Rank, len(targets))
+			for i := range targets {
+				ranks[i] = list.Rank{Index: i}
+			}
+			return ranks
+		}
+		words := strings.Fields(strings.ToLower(term))
+		var ranks []list.Rank
+		for i, t := range targets {
+			tl := strings.ToLower(t)
+			matches := true
+			for _, w := range words {
+				if !strings.Contains(tl, w) {
+					matches = false
+					break
+				}
+			}
+			if matches {
+				ranks = append(ranks, list.Rank{Index: i})
+			}
+		}
+		return ranks
+	}
+
 	return &App{list: l}
 }
 
@@ -117,12 +149,13 @@ func (a *App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			r := rune(s[0])
 			if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') {
 				if a.list.FilterState() != list.Filtering {
-					// Simulate pressing the filter key to activate
+					// Simulate pressing the filter key to activate, then feed the char
 					slash := tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'/'}}
-					a.list, _ = a.list.Update(slash)
+					var c1 tea.Cmd
-					// Now feed the original key into the active filter
+					a.list, c1 = a.list.Update(slash)
-					a.list, _ = a.list.Update(msg)
+					var c2 tea.Cmd
-					return a, nil
+					a.list, c2 = a.list.Update(msg)
+					return a, tea.Batch(c1, c2)
 				}
 			}
 		}

internal/ui/ui_test.go

@@ -34,20 +34,59 @@ func TestApp_AutoFilterOnTyping(t *testing.T) {
 		{Name: "Other Station", Url: "http://other", Codec: "AAC", Bitrate: "64", Tags: "news"},
 	})
 
-	// Simulate typing 'W' (should auto enter filter and filter to WFMT)
+	// Simulate typing 'W' (auto enter filter). Drive any returned cmds.
-	model, _ := app.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'W'}})
+	model, cmd := app.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'W'}})
 	a := model.(*App)
+	for cmd != nil {
+		msg := cmd()
+		if msg == nil {
+			break
+		}
+		model, cmd = a.Update(msg.(tea.Msg))
+		a = model.(*App)
+	}
 
-	// After auto filter start + 'W', the filter value should be "W" and state Filtering or applied
 	fv := a.list.FilterValue()
 	if fv != "W" {
 		t.Errorf("expected filter value 'W' after typing W, got %q", fv)
 	}
-
-	// The visible items should be filtered (at least the WFMT one should match)
 	visible := a.list.VisibleItems()
 	if len(visible) == 0 {
 		t.Error("expected some visible items after filter 'W'")
 	}
-	// Check that 'Other' is not the only one, or better, since fuzzy, 'W' may match others weakly, but at least not empty
+
+	// Now type the rest of "WFMT", driving cmds each time
+	for _, r := range "FMT" {
+		model, cmd = a.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{r}})
+		a = model.(*App)
+		for cmd != nil {
+			msg := cmd()
+			if msg == nil {
+				break
+			}
+			model, cmd = a.Update(msg.(tea.Msg))
+			a = model.(*App)
+		}
+	}
+
+	fv = a.list.FilterValue()
+	if fv != "WFMT" {
+		t.Errorf("expected filter value 'WFMT', got %q", fv)
+	}
+
+	// Note: in live typing simulation, state may stay 'filtering' and filteredItems update may depend on internal cmd processing.
+	// For verifying the custom substring filter logic itself, use SetFilterText which synchronously applies.
+	a.list.SetFilterText("WFMT")
+
+	visible = a.list.VisibleItems()
+	if len(visible) != 1 {
+		t.Errorf("expected exactly 1 item for 'WFMT' substring filter, got %d", len(visible))
+	}
+	if len(visible) > 0 {
+		if it, ok := visible[0].(item); ok {
+			if it.station.Name != "WFMT 98.7" {
+				t.Errorf("expected 'WFMT 98.7' to be the match, got %q", it.station.Name)
+			}
+		}
+	}
 }