Merge agent and mode into one (#1689)

The concept of mode has been deprecated, there is now only the agent field in the config.

An agent can be cycled through as your primary agent with <tab> or you can spawn a subagent by @ mentioning it. if you include a description of when to use it, the primary agent will try to automatically use it

Full docs here: https://opencode.ai/docs/agents/

3 files changed, 74 insertions, 2 deletions

diff --git a/packages/tui/internal/components/chat/editor.go b/packages/tui/internal/components/chat/editor.go
index 1263a6e72..509de6244 100644
--- a/packages/tui/internal/components/chat/editor.go
+++ b/packages/tui/internal/components/chat/editor.go
@@ -288,6 +288,31 @@ func (m *editorComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.textarea.InsertAttachment(attachment)
 			m.textarea.InsertString(" ")
 			return m, nil
+		case "agents":
+			atIndex := m.textarea.LastRuneIndex('@')
+			if atIndex == -1 {
+				// Should not happen, but as a fallback, just insert.
+				m.textarea.InsertString(msg.Item.Value + " ")
+				return m, nil
+			}
+
+			cursorCol := m.textarea.CursorColumn()
+			m.textarea.ReplaceRange(atIndex, cursorCol, "")
+
+			name := msg.Item.Value
+			attachment := &attachment.Attachment{
+				ID:      uuid.NewString(),
+				Type:    "agent",
+				Display: "@" + name,
+				Source: &attachment.AgentSource{
+					Name: name,
+				},
+			}
+
+			m.textarea.InsertAttachment(attachment)
+			m.textarea.InsertString(" ")
+			return m, nil
+
 		default:
 			slog.Debug("Unknown provider", "provider", msg.Item.ProviderID)
 			return m, nil
diff --git a/packages/tui/internal/components/chat/message.go b/packages/tui/internal/components/chat/message.go
index 0a1982718..60d0fab55 100644
--- a/packages/tui/internal/components/chat/message.go
+++ b/packages/tui/internal/components/chat/message.go
@@ -209,6 +209,7 @@ func renderText(
 	width int,
 	extra string,
 	fileParts []opencode.FilePart,
+	agentParts []opencode.AgentPart,
 	toolCalls ...opencode.ToolPart,
 ) string {
 	t := theme.CurrentTheme()
@@ -229,9 +230,47 @@ func renderText(
 
 		// Apply highlighting to filenames and base style to rest of text BEFORE wrapping
 		textLen := int64(len(text))
+
+		// Collect all parts to highlight (both file and agent parts)
+		type highlightPart struct {
+			start int64
+			end   int64
+			color compat.AdaptiveColor
+		}
+		var highlights []highlightPart
+
+		// Add file parts with secondary color
 		for _, filePart := range fileParts {
-			highlight := base.Foreground(t.Secondary())
-			start, end := filePart.Source.Text.Start, filePart.Source.Text.End
+			highlights = append(highlights, highlightPart{
+				start: filePart.Source.Text.Start,
+				end:   filePart.Source.Text.End,
+				color: t.Secondary(),
+			})
+		}
+
+		// Add agent parts with secondary color (same as file parts)
+		for _, agentPart := range agentParts {
+			highlights = append(highlights, highlightPart{
+				start: agentPart.Source.Start,
+				end:   agentPart.Source.End,
+				color: t.Secondary(),
+			})
+		}
+
+		// Sort highlights by start position
+		slices.SortFunc(highlights, func(a, b highlightPart) int {
+			if a.start < b.start {
+				return -1
+			}
+			if a.start > b.start {
+				return 1
+			}
+			return 0
+		})
+
+		for _, part := range highlights {
+			highlight := base.Foreground(part.color)
+			start, end := part.start, part.end
 
 			if end > textLen {
 				end = textLen
diff --git a/packages/tui/internal/components/chat/messages.go b/packages/tui/internal/components/chat/messages.go
index 5702cec5d..46036b75f 100644
--- a/packages/tui/internal/components/chat/messages.go
+++ b/packages/tui/internal/components/chat/messages.go
@@ -300,12 +300,17 @@ func (m *messagesComponent) renderView() tea.Cmd {
 						}
 						remainingParts := message.Parts[partIndex+1:]
 						fileParts := make([]opencode.FilePart, 0)
+						agentParts := make([]opencode.AgentPart, 0)
 						for _, part := range remainingParts {
 							switch part := part.(type) {
 							case opencode.FilePart:
 								if part.Source.Text.Start >= 0 && part.Source.Text.End >= part.Source.Text.Start {
 									fileParts = append(fileParts, part)
 								}
+							case opencode.AgentPart:
+								if part.Source.Start >= 0 && part.Source.End >= part.Source.Start {
+									agentParts = append(agentParts, part)
+								}
 							}
 						}
 						flexItems := []layout.FlexItem{}
@@ -355,6 +360,7 @@ func (m *messagesComponent) renderView() tea.Cmd {
 								width,
 								files,
 								fileParts,
+								agentParts,
 							)
 							content = lipgloss.PlaceHorizontal(
 								m.width,
@@ -433,6 +439,7 @@ func (m *messagesComponent) renderView() tea.Cmd {
 									width,
 									"",
 									[]opencode.FilePart{},
+									[]opencode.AgentPart{},
 									toolCallParts...,
 								)
 								content = lipgloss.PlaceHorizontal(
@@ -453,6 +460,7 @@ func (m *messagesComponent) renderView() tea.Cmd {
 								width,
 								"",
 								[]opencode.FilePart{},
+								[]opencode.AgentPart{},
 								toolCallParts...,
 							)
 							content = lipgloss.PlaceHorizontal(