feat(tui-go): idea board viewer

OverlayIdeas (opened with I, global/cross-session) lists the idea board in the
artifact-viewer shell: ↑↓ to move, x/d to remove (sends DiscardIdea, optimistic
drop), esc to close. Pull-based via ListIdeas -> idea.list.

apps/tui-go/internal/app/ideacard.go

@@ -0,0 +1,82 @@
+package app
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+// ideacard.go renders the cross-session idea board (OverlayIdeas): the ideas the router
+// captured while the operator rubber-ducked, each removable. Modeled on the artifact
+// viewer's list shell, but ideas are short notes so there is no separate content pane.
+
+// ideaListRows is how many idea rows fit in the board (the rest is title + hints).
+func (m Model) ideaListRows() int {
+	rows := m.height*70/100 - 5
+	if rows < 1 {
+		rows = 1
+	}
+	if rows > len(m.ideas) {
+		rows = len(m.ideas)
+	}
+	if rows < 1 {
+		rows = 1
+	}
+	return rows
+}
+
+func (m Model) ideasModal() string {
+	t := m.theme
+	w := m.modalWidth()
+
+	var b strings.Builder
+	b.WriteString(m.titleLine("ideas"))
+	if len(m.ideas) > 0 {
+		b.WriteString(mbg(t, "   ("+itoa(m.ideasIndex+1)+"/"+itoa(len(m.ideas))+")", t.P.Faint))
+	}
+	b.WriteString(mbg(t, "   · captured while rubber-ducking", t.P.Faint) + "\n\n")
+
+	if m.ideasLoading {
+		b.WriteString(mbg(t, "  loading…", t.P.Faint) + "\n")
+		b.WriteString("\n" + modalHints(t, [][2]string{{"esc", "close"}}))
+		return t.Overlay.Width(w).Render(b.String())
+	}
+	if len(m.ideas) == 0 {
+		b.WriteString(mbg(t, "  no ideas yet — they're saved as you think out loud with the router", t.P.Faint) + "\n")
+		b.WriteString("\n" + modalHints(t, [][2]string{{"esc", "close"}}))
+		return t.Overlay.Width(w).Render(b.String())
+	}
+
+	// Windowed list, keeping the selected row in view.
+	rows := m.ideaListRows()
+	off := 0
+	if len(m.ideas) > rows {
+		off = m.ideasIndex - rows/2
+		if off < 0 {
+			off = 0
+		}
+		if off > len(m.ideas)-rows {
+			off = len(m.ideas) - rows
+		}
+	}
+	end := off + rows
+	if end > len(m.ideas) {
+		end = len(m.ideas)
+	}
+	textW := w - 8
+	for i := off; i < end; i++ {
+		marker := mbg(t, "  ", t.P.BgPanel)
+		fg := t.P.Fg
+		if i == m.ideasIndex {
+			marker = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▸ ")
+			fg = t.P.FgStrong
+		}
+		text := strings.ReplaceAll(m.ideas[i].Text, "\n", " ")
+		b.WriteString(marker + lipgloss.NewStyle().Foreground(fg).Background(t.P.BgPanel).Render(clip(text, textW)) + "\n")
+	}
+
+	b.WriteString("\n" + modalHints(t, [][2]string{
+		{"↑↓", "move"}, {"x", "remove"}, {"esc", "close"},
+	}))
+	return t.Overlay.Width(w).Render(b.String())
+}

apps/tui-go/internal/app/ideacard_test.go

@@ -0,0 +1,71 @@
+package app
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/correx/tui-go/internal/protocol"
+	"github.com/correx/tui-go/internal/ws"
+)
+
+func ideaModel() (Model, *ws.Client) {
+	client := ws.New("", 0) // unconnected; Send buffers, Drain reads it back
+	m := NewModel(client)
+	m.width, m.height = 120, 40
+	m.theme = NewTheme(SoftBlue)
+	m.openIdeas() // sets OverlayIdeas + sends a ListIdeas frame
+	m.applyServer(protocol.ServerMessage{
+		Type: protocol.TypeIdeaList,
+		Ideas: []protocol.IdeaDto{
+			{IdeaID: "i1", Text: "cache the repo map", CapturedAtMs: 1000},
+			{IdeaID: "i2", Text: "add --dry-run", CapturedAtMs: 2000},
+		},
+	})
+	return m, client
+}
+
+func TestIdeaBoardOpensAndRenders(t *testing.T) {
+	m, _ := ideaModel()
+	if m.overlay != OverlayIdeas {
+		t.Fatalf("want OverlayIdeas, got %v", m.overlay)
+	}
+	out := m.ideasModal()
+	for _, want := range []string{"ideas", "cache the repo map", "add --dry-run"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("board missing %q:\n%s", want, out)
+		}
+	}
+}
+
+func TestIdeaRemoveSendsDiscardAndDropsRow(t *testing.T) {
+	m, client := ideaModel()
+	_ = client.Drain() // drop the ListIdeas frame from openIdeas
+
+	updated, _ := m.handleOverlayKey(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune("x")})
+	m = updated.(Model)
+
+	if len(m.ideas) != 1 || m.ideas[0].IdeaID != "i2" {
+		t.Fatalf("expected i1 removed, got %+v", m.ideas)
+	}
+	frames := client.Drain()
+	if len(frames) != 1 {
+		t.Fatalf("expected one DiscardIdea frame, got %d", len(frames))
+	}
+	var raw map[string]any
+	if err := json.Unmarshal(frames[0], &raw); err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	if raw["type"] != "com.correx.apps.server.protocol.ClientMessage.DiscardIdea" || raw["ideaId"] != "i1" {
+		t.Fatalf("expected DiscardIdea i1, got %+v", raw)
+	}
+}
+
+func TestIdeaBoardEmptyState(t *testing.T) {
+	m, _ := ideaModel()
+	m.applyServer(protocol.ServerMessage{Type: protocol.TypeIdeaList, Ideas: nil})
+	if !strings.Contains(m.ideasModal(), "no ideas yet") {
+		t.Fatalf("expected empty state, got:\n%s", m.ideasModal())
+	}
+}

apps/tui-go/internal/app/model.go

@@ -52,6 +52,7 @@ const (
 	OverlayArtifacts
 	OverlayConfig
 	OverlayStats
+	OverlayIdeas
 )
 
 // RouterEntry is one line in a session's conversation transcript.
@@ -253,6 +254,11 @@ type Model struct {
 	statsFor     string // sessionId the current stats belong to
 	statsLoading bool
 
+	// idea board (OverlayIdeas) — cross-session, populated by the idea.list reply
+	ideas        []protocol.IdeaDto
+	ideasIndex   int
+	ideasLoading bool
+
 	// command palette
 	paletteFilter string
 	paletteIndex  int

apps/tui-go/internal/app/overlays.go

@@ -59,6 +59,8 @@ func (m Model) renderOverlay(base string) string {
 		return m.center(m.configModal())
 	case OverlayStats:
 		return m.center(m.statsModal())
+	case OverlayIdeas:
+		return m.center(m.ideasModal())
 	}
 	return base
 }

apps/tui-go/internal/app/server.go

@@ -316,6 +316,12 @@ func (m *Model) applyServer(msg protocol.ServerMessage) {
 		m.stats = msg.Stats
 		m.statsFor = msg.SessionID
 		m.statsLoading = false
+	case protocol.TypeIdeaList:
+		m.ideas = msg.Ideas
+		m.ideasLoading = false
+		if m.ideasIndex >= len(m.ideas) {
+			m.ideasIndex = 0
+		}
 	case protocol.TypeConfigSnapshot:
 		m.configFields = msg.ConfigFields
 		m.configRestart = msg.ConfigRestartRequired
@@ -360,7 +366,8 @@ func sessionIDOf(msg protocol.ServerMessage) string {
 		protocol.TypeProtocolError, protocol.TypeProviderStatus,
 		protocol.TypeWorkflowList, protocol.TypeRouterResponse,
 		protocol.TypeModelChanged, protocol.TypeModelList, protocol.TypeResourceStatus,
-		protocol.TypeArtifactList, protocol.TypeConfigSnapshot, protocol.TypeSessionStats:
+		protocol.TypeArtifactList, protocol.TypeConfigSnapshot, protocol.TypeSessionStats,
+		protocol.TypeIdeaList:
 		return ""
 	default:
 		return msg.SessionID

apps/tui-go/internal/app/update.go

@@ -176,6 +176,8 @@ func (m Model) handleNormalKey(k tea.KeyMsg) (tea.Model, tea.Cmd) {
 		m.overlay = OverlayToolPalette
 	case "v":
 		m.openArtifacts()
+	case "I":
+		m.openIdeas()
 	case "S":
 		m.openStats()
 	case "g":
@@ -442,6 +444,28 @@ func (m Model) handleOverlayKey(k tea.KeyMsg) (tea.Model, tea.Cmd) {
 		if runeIs(k, "S") {
 			m.overlay = OverlayNone
 		}
+	case OverlayIdeas:
+		switch {
+		case k.Type == tea.KeyUp || runeIs(k, "k"):
+			if m.ideasIndex > 0 {
+				m.ideasIndex--
+			}
+		case k.Type == tea.KeyDown || runeIs(k, "j"):
+			if m.ideasIndex < len(m.ideas)-1 {
+				m.ideasIndex++
+			}
+		case runeIs(k, "x") || runeIs(k, "d"):
+			if m.ideasIndex >= 0 && m.ideasIndex < len(m.ideas) {
+				m.client.Send(protocol.DiscardIdea(m.ideas[m.ideasIndex].IdeaID))
+				// Optimistic removal; the server's fresh idea.list reply reconciles.
+				m.ideas = append(m.ideas[:m.ideasIndex], m.ideas[m.ideasIndex+1:]...)
+				if m.ideasIndex >= len(m.ideas) && m.ideasIndex > 0 {
+					m.ideasIndex--
+				}
+			}
+		case runeIs(k, "I"):
+			m.overlay = OverlayNone
+		}
 	}
 	return m, nil
 }
@@ -463,6 +487,17 @@ func (m *Model) openArtifacts() {
 	m.client.Send(protocol.ListArtifacts(m.selectedID))
 }
 
+// openIdeas opens the cross-session idea board and requests it from the server. The board
+// is global (not session-scoped), so it opens from anywhere — including the idle list.
+func (m *Model) openIdeas() {
+	m.overlay = OverlayIdeas
+	m.ideasIndex = 0
+	if m.ideas == nil {
+		m.ideasLoading = true
+	}
+	m.client.Send(protocol.ListIdeas())
+}
+
 // openStats opens the session-stats pane for the selected session and requests its
 // metrics from the server. No-op when no session is selected.
 func (m *Model) openStats() {

apps/tui-go/internal/protocol/golden_test.go

@@ -149,6 +149,21 @@ func TestDecodeGoldenServerFrames(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "idea.list carries the cross-session board",
+			json: `{"type":"idea.list","ideas":[{"ideaId":"i1","text":"cache the repo map","capturedAtMs":1000},` +
+				`{"ideaId":"i2","text":"add --dry-run","capturedAtMs":2000}]}`,
+			wantType:  TypeIdeaList,
+			eventBear: false,
+			check: func(t *testing.T, m ServerMessage) {
+				if len(m.Ideas) != 2 {
+					t.Fatalf("idea.list ideas: %+v", m.Ideas)
+				}
+				if m.Ideas[0].IdeaID != "i1" || m.Ideas[0].Text != "cache the repo map" || m.Ideas[0].CapturedAtMs != 1000 {
+					t.Fatalf("idea.list idea[0]: %+v", m.Ideas[0])
+				}
+			},
+		},
 		{
 			name: "workflow.proposed carries candidate workflows",
 			json: `{"type":"workflow.proposed","sessionId":"s1","proposalId":"prop-1","prompt":"Run one?",` +
@@ -233,6 +248,16 @@ func TestEncodeGoldenClientFrames(t *testing.T) {
 				}
 			},
 		},
+		{
+			name:     "DiscardIdea carries the ideaId",
+			frame:    DiscardIdea("i1"),
+			wantType: clientPrefix + "DiscardIdea",
+			check: func(t *testing.T, raw map[string]any) {
+				if raw["ideaId"] != "i1" {
+					t.Fatalf("DiscardIdea ideaId: %+v", raw)
+				}
+			},
+		},
 		{
 			name: "ClarificationResponse carries ids + answers",
 			frame: ClarificationResponse("s1", "analyst", "req-1",

apps/tui-go/internal/protocol/protocol.go

@@ -54,6 +54,7 @@ const (
 	TypeArtifactList     = "artifact.list"
 	TypeConfigSnapshot   = "config.snapshot"
 	TypeSessionStats     = "session.stats"
+	TypeIdeaList         = "idea.list"
 )
 
 // ServerMessage is a flat decode of every server->client variant. Field names
@@ -146,6 +147,16 @@ type ServerMessage struct {
 	Prompt          string                `json:"prompt"`
 	OriginalRequest string                `json:"originalRequest"`
 	Candidates      []ProposedWorkflowDto `json:"candidates"`
+
+	// idea.list — the cross-session idea board
+	Ideas []IdeaDto `json:"ideas"`
+}
+
+// IdeaDto is one idea on the cross-session board. Mirrors the Kotlin IdeaDto.
+type IdeaDto struct {
+	IdeaID       string `json:"ideaId"`
+	Text         string `json:"text"`
+	CapturedAtMs int64  `json:"capturedAtMs"`
 }
 
 // ProposedWorkflowDto is one candidate workflow the router suggests, with a short
@@ -385,6 +396,16 @@ func GetConfig() []byte {
 	return encode("GetConfig", map[string]any{})
 }
 
+// ListIdeas requests the cross-session idea board (replied to with an idea.list).
+func ListIdeas() []byte {
+	return encode("ListIdeas", map[string]any{})
+}
+
+// DiscardIdea removes an idea from the board (server tombstones it; replies with a fresh idea.list).
+func DiscardIdea(ideaID string) []byte {
+	return encode("DiscardIdea", map[string]any{"ideaId": ideaID})
+}
+
 // UpdateConfig asks the server to apply and persist a config patch (key -> string value).
 func UpdateConfig(patch map[string]string) []byte {
 	return encode("UpdateConfig", map[string]any{"patch": patch})