revert vt-go to v0.1.0 (v0.2.0 scrollback changes break mosh)

cmd/mosh-wasm/main.go

@@ -158,7 +158,8 @@ func (s *session) recvLoop() {
 		t := s.client.Transport()
 		oldNum := t.LastRecvOldNum()
 		newNum := t.LastRecvNewNum()
-		s.tracker.applyDiff(diff, oldNum, newNum)
+		throwawayNum := t.ThrowawayNum()
+		s.tracker.applyDiff(diff, oldNum, newNum, throwawayNum)
 	}
 }
 

cmd/mosh-wasm/state.go

@@ -41,7 +41,8 @@ func newStateTracker(cols, rows int) *stateTracker {
 }
 
 // applyDiff processes an incoming server diff using state tracking.
-func (st *stateTracker) applyDiff(diff []byte, oldNum, newNum uint64) {
+// throwawayNum is the server's indication of which states it no longer references.
+func (st *stateTracker) applyDiff(diff []byte, oldNum, newNum, throwawayNum uint64) {
 	st.mu.Lock()
 	defer st.mu.Unlock()
 
@@ -60,11 +61,13 @@ func (st *stateTracker) applyDiff(diff []byte, oldNum, newNum uint64) {
 	// Need the base state to apply the diff.
 	base, ok := st.states[oldNum]
 	if !ok {
-		return
-	}
-
-	// Restore shadow to base state if needed.
-	if st.shadowState != oldNum {
+		// After a resize we have no states. Start fresh with a
+		// clean emulator so the first post-resize diff works.
+		st.shadow = vt.NewEmulator(st.cols, st.rows)
+		st.shadowState = oldNum
+		base = mosh.SnapshotEmulator(st.shadow, true)
+		st.states[oldNum] = base
+	} else if st.shadowState != oldNum {
 		st.shadow = vt.NewEmulator(st.cols, st.rows)
 		// Write the base framebuffer as ANSI to restore state.
 		if base != nil {
@@ -91,9 +94,13 @@ func (st *stateTracker) applyDiff(diff []byte, oldNum, newNum uint64) {
 		st.latestState = newNum
 	}
 
-	// Bound states list.
-	if len(st.states) > 128 {
-		st.pruneStates()
+	// Prune states the server no longer references.
+	if throwawayNum > 0 {
+		for n := range st.states {
+			if n < throwawayNum {
+				delete(st.states, n)
+			}
+		}
 	}
 
 	// Display diff: compute ANSI difference between displayed and latest.
@@ -131,24 +138,3 @@ func (st *stateTracker) resize(cols, rows int) {
 	st.displayedFB = nil
 }
 
-func (st *stateTracker) pruneStates() {
-	if len(st.states) <= 64 {
-		return
-	}
-	// Keep the 64 most recent states.
-	var nums []uint64
-	for n := range st.states {
-		nums = append(nums, n)
-	}
-	// Simple sort for small lists.
-	for i := range nums {
-		for j := i + 1; j < len(nums); j++ {
-			if nums[j] < nums[i] {
-				nums[i], nums[j] = nums[j], nums[i]
-			}
-		}
-	}
-	for _, n := range nums[:len(nums)-64] {
-		delete(st.states, n)
-	}
-}

framebuffer.go

@@ -15,8 +15,10 @@ const (
 	attrFaint         = 1 << 1
 	attrItalic        = 1 << 2
 	attrBlink         = 1 << 3
-	attrReverse       = 1 << 4
-	attrStrikethrough = 1 << 5
+	attrRapidBlink    = 1 << 4
+	attrReverse       = 1 << 5
+	attrConceal       = 1 << 6
+	attrStrikethrough = 1 << 7
 )
 
 // Framebuffer represents a terminal screen state for mosh SSP.
@@ -172,11 +174,11 @@ func (fb *Framebuffer) fullRedraw() []byte {
 			buf = append(buf, "\r\n"...)
 		}
 		rowOff := y * fb.W
-		// Track trailing spaces to avoid sending them.
+		// Track trailing default-attr spaces to avoid sending them.
 		lastNonSpace := -1
 		for x := fb.W - 1; x >= 0; x-- {
 			c := &fb.Cells[rowOff+x]
-			if c.Rune != ' ' || c.Rune == 0 || c.Attr != (Attr{}) {
+			if (c.Rune != ' ' && c.Rune != 0) || c.Attr != (Attr{}) {
 				lastNonSpace = x
 				break
 			}

transport.go

@@ -379,6 +379,14 @@ func (t *Transport) LastRecvNewNum() uint64 {
 	return t.lastRecvNewNum
 }
 
+// ThrowawayNum returns the server's throwaway number — states below this
+// are no longer referenced by the server and can be safely pruned.
+func (t *Transport) ThrowawayNum() uint64 {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.throwawayNum
+}
+
 // LastRecv returns the time of the last received datagram.
 func (t *Transport) LastRecv() time.Time {
 	t.mu.Lock()