Struct harness

internal/ui/program.go:95–142

)

type harness struct {
	runner    AgentRunner
	usageFunc UsageFunc

	width, height int

	viewport  viewport.Model
	debugView viewport.Model // bottom panel, visible only when debug.Enabled()
	input     textinput.Model
	spinner   spinner.Model

	state          modelState
	approvalPrompt string
	approvalDetail string // optional diff/payload shown in the approval modal
	approvalReply  chan bool
	followBottom   bool // auto-scroll viewport to bottom on new content

	// debug-panel interaction state
	debugFocus    bool      // Tab moves focus between input and debug panel
	debugMode     debugMode // list (overview) or detail (one event's payload)
	debugSelected uint64    // ID of the currently-selected event

	// banner shine animation state. bannerEnd is the byte offset in output
	// where the banner ends, so each tick can swap the banner without
	// touching the rest of the scrollback. bannerWidth is captured at
	// construction — it has to be, because by the time Init() runs main.go
	// has already redirected os.Stdout into the alt-screen pipe and
	// TermWidth() comes back as zero.
	shineCol    int
	shineTick   int  // frame counter; eased into shineCol each frame
	shineDone   bool
	bannerEnd   int
	bannerWidth int

	// MCP background-loading state. mcpLoading is true between the
	// ProgressBegin and ProgressDone messages; the status line shows the
	// current server and an X/N counter while connections are in flight.
	mcpLoading bool
	mcpTotal   int
	mcpDone    int
	mcpFailed  int
	mcpCurrent string

	// output must be a pointer: Bubble Tea passes the model by value through
	// Update, and strings.Builder panics when copied (copyCheck on its
	// internal self-pointer). The pointer survives the copy intact.
	output *strings.Builder
}

type debugMode int