tui: reset auto-follow baseline on new turn to stop viewport jump

startTurnWithImages clears the previous turn's tool-call overlay and
pins scrollOffset to 0. Without also resetting prevChatLen/prevChatCols,
the auto-follow guard on the next render sees a synthetic negative
delta equal to the number of overlay rows that were cleared, and
nudges scrollOffset by that amount. On terminals that mirror zot's
chat-pane scroll into their native scrollbar this is visible as a
viewport jump the instant the user presses enter on a follow-up
prompt.

Zero them out in the same locked block so the guard short-circuits
on the very next render, the same way it already does on column
resize. The legitimate "user scrolled up while content streams in"
case is unaffected because prevChatLen is repopulated on that first
post-submit render.

commit: 43da5e5249e11af0609bfbde8a4fd33c03754bd8
author: patriceckhart · 5mo ago · 2026-05-12 18:43 UTC
parent: 1030ae5
signature: unsigned
refs: tag: v0.1.77

1 file · +11 -1

M internal/agent/modes/interactive.go +11 -1


@@ -3167,7 +3167,17 @@ func (i *Interactive) startTurnWithImages(parent context.Context, prompt string,
3167	3167		i.toolCalls = map[string]*tui.ToolCallView{}
3168	3168		i.toolOrder = nil
3169	3169		i.scrollOffset = 0 // jump back to the bottom on new turn
3170		-	i.parkedTurn = 0 // starting a turn clears the /jump parked state
	3170	+	// Reset the auto-follow baseline so the very next render at
	3171	+	// interactive.go:1053 doesn't see a synthetic shrink between
	3172	+	// "last frame had the previous turn's tool overlay" and
	3173	+	// "this frame had it cleared above". Without this, the guard
	3174	+	// reads delta = -(rows in cleared overlay) and decrements
	3175	+	// scrollOffset, which on terminals that mirror zot's pane
	3176	+	// scroll into the host scrollbar visibly yanks the viewport.
	3177	+	// See autofollow_shrink_test.go for the exact arithmetic.
	3178	+	i.prevChatLen = 0
	3179	+	i.prevChatCols = 0
	3180	+	i.parkedTurn = 0 // starting a turn clears the /jump parked state
3171	3181		i.parkedTotal = 0
3172	3182		i.helpBlock = nil // hide the help block once the user asks something
3173	3183		i.mu.Unlock()


@@ -3167,7 +3167,17 @@ func (i *Interactive) startTurnWithImages(parent context.Context, prompt string,
3167		i.toolCalls = map[string]*tui.ToolCallView{}	3167		i.toolCalls = map[string]*tui.ToolCallView{}
3168		i.toolOrder = nil	3168		i.toolOrder = nil
3169		i.scrollOffset = 0 // jump back to the bottom on new turn	3169		i.scrollOffset = 0 // jump back to the bottom on new turn
3170	-	i.parkedTurn = 0 // starting a turn clears the /jump parked state	3170	+	// Reset the auto-follow baseline so the very next render at
			3171	+	// interactive.go:1053 doesn't see a synthetic shrink between
			3172	+	// "last frame had the previous turn's tool overlay" and
			3173	+	// "this frame had it cleared above". Without this, the guard
			3174	+	// reads delta = -(rows in cleared overlay) and decrements
			3175	+	// scrollOffset, which on terminals that mirror zot's pane
			3176	+	// scroll into the host scrollbar visibly yanks the viewport.
			3177	+	// See autofollow_shrink_test.go for the exact arithmetic.
			3178	+	i.prevChatLen = 0
			3179	+	i.prevChatCols = 0
			3180	+	i.parkedTurn = 0 // starting a turn clears the /jump parked state
3171		i.parkedTotal = 0	3181		i.parkedTotal = 0
3172		i.helpBlock = nil // hide the help block once the user asks something	3182		i.helpBlock = nil // hide the help block once the user asks something
3173		i.mu.Unlock()	3183		i.mu.Unlock()