wip

internal/app/child.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"bytes"
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
@@ -108,11 +109,15 @@ type Child struct {
 
 	// ringMu guards ring. The ring buffer carries the last `ringCap`
 	// bytes the PTY produced, used by SPEC §7 get_process_output stream
-	// mode and search_output scrollback.
+	// mode and search_output scrollback. The ring is a fixed-size byte
+	// array with a wrap-around write index — no per-chunk reslice or
+	// reallocation. StreamRead serves contiguous slices by copying out
+	// of the (possibly wrapped) ring into a fresh buffer.
 	ringMu     sync.Mutex
-	ring       []byte
-	ringStart  int64 // absolute offset of ring[0]
-	ringWrites int64 // cumulative bytes written
+	ring       []byte // length == ringCap once allocated
+	ringPos    int    // next byte to overwrite
+	ringFull   bool   // true once ringWrites ≥ ringCap
+	ringWrites int64  // cumulative bytes written
 
 	// portsMu guards ports. Best-effort port detection: regex on stream.
 	portsMu sync.Mutex
@@ -127,10 +132,36 @@ type Child struct {
 	// exits and calls Start to bring the entry back up. Cleared when the
 	// user explicitly kills the process from the palette.
 	autoRestart atomic.Bool
+
+	// persistFn is set by Session after Spawn registers the entry. The
+	// callback mirrors mutable bits (name, auto-restart) into the
+	// persist store so a restarted patterm can rebuild this entry. Nil
+	// when no persist store is attached (unit tests / non-command
+	// entries).
+	persistMu sync.Mutex
+	persistFn func(*Child)
 }
 
-func (c *Child) SetAutoRestart(v bool) { c.autoRestart.Store(v) }
-func (c *Child) AutoRestart() bool     { return c.autoRestart.Load() }
+func (c *Child) SetAutoRestart(v bool) {
+	c.autoRestart.Store(v)
+	c.firePersist()
+}
+func (c *Child) AutoRestart() bool { return c.autoRestart.Load() }
+
+func (c *Child) setPersistFn(fn func(*Child)) {
+	c.persistMu.Lock()
+	c.persistFn = fn
+	c.persistMu.Unlock()
+}
+
+func (c *Child) firePersist() {
+	c.persistMu.Lock()
+	fn := c.persistFn
+	c.persistMu.Unlock()
+	if fn != nil {
+		fn(c)
+	}
+}
 
 // PortSighting is one entry returned by get_process_ports.
 type PortSighting struct {
@@ -152,7 +183,7 @@ func newChildEntry(id, name string, kind ChildKind, argv, env []string, parentID
 		Kind:      kind,
 		ParentID:  parentID,
 		PresetRef: presetRef,
-		ring:      make([]byte, 0, ringCap),
+		ring:      make([]byte, ringCap),
 	}
 	st := StatusStopped
 	c.status.Store(&st)
@@ -254,6 +285,7 @@ func (c *Child) SetName(name string) {
 	c.nameMu.Lock()
 	c.Name = name
 	c.nameMu.Unlock()
+	c.firePersist()
 }
 
 // ScreenVersion returns the current emulator snapshot version, bumped
@@ -302,13 +334,22 @@ func (c *Child) recordWrite(chunk []byte) {
 	c.lastWriteNS.Store(time.Now().UnixNano())
 	c.screenVersion.Add(1)
 	c.ringMu.Lock()
-	c.ring = append(c.ring, chunk...)
-	c.ringWrites += int64(len(chunk))
-	if len(c.ring) > ringCap {
-		drop := len(c.ring) - ringCap
-		c.ring = c.ring[drop:]
-		c.ringStart += int64(drop)
+	// Chunks larger than ringCap are tail-truncated — only the last
+	// ringCap bytes of the chunk can survive.
+	src := chunk
+	if len(src) > ringCap {
+		src = src[len(src)-ringCap:]
 	}
+	for written := 0; written < len(src); {
+		n := copy(c.ring[c.ringPos:], src[written:])
+		c.ringPos += n
+		if c.ringPos >= ringCap {
+			c.ringPos = 0
+			c.ringFull = true
+		}
+		written += n
+	}
+	c.ringWrites += int64(len(chunk))
 	c.ringMu.Unlock()
 	c.scanPortsFromChunk(chunk)
 }
@@ -316,6 +357,11 @@ func (c *Child) recordWrite(chunk []byte) {
 // scanPortsFromChunk does best-effort port detection on a PTY chunk.
 // SPEC §7 get_process_ports — no probing, just stream scanning.
 func (c *Child) scanPortsFromChunk(chunk []byte) {
+	// Cheap prefix check: most chunks don't contain a URL. Bail before
+	// running the regex DFA over the whole chunk.
+	if !bytes.Contains(chunk, []byte("http")) {
+		return
+	}
 	matches := portRegex.FindAllSubmatch(chunk, -1)
 	if len(matches) == 0 {
 		return
@@ -364,16 +410,38 @@ func (c *Child) Ports() []PortSighting {
 func (c *Child) StreamRead(since int64) ([]byte, int64) {
 	c.ringMu.Lock()
 	defer c.ringMu.Unlock()
-	if since < c.ringStart {
-		since = c.ringStart
+	end := c.ringWrites
+	var ringStart int64
+	if c.ringFull {
+		ringStart = end - int64(ringCap)
+	}
+	if since < ringStart {
+		since = ringStart
 	}
-	end := c.ringStart + int64(len(c.ring))
 	if since >= end {
 		return nil, end
 	}
-	start := int(since - c.ringStart)
-	out := make([]byte, end-since)
-	copy(out, c.ring[start:])
+	n := int(end - since)
+	out := make([]byte, n)
+	// Locate `since` in the ring. When the buffer hasn't wrapped yet,
+	// bytes 0..ringPos hold writes 0..ringPos. After wrap, ringPos
+	// points at the oldest byte, and the freshest byte is at
+	// (ringPos - 1) mod ringCap.
+	var pos int
+	if c.ringFull {
+		skip := int(since - ringStart) // bytes after the oldest
+		pos = (c.ringPos + skip) % ringCap
+	} else {
+		pos = int(since)
+	}
+	first := ringCap - pos
+	if first > n {
+		first = n
+	}
+	copy(out, c.ring[pos:pos+first])
+	if first < n {
+		copy(out[first:], c.ring[:n-first])
+	}
 	return out, end
 }
 
@@ -395,19 +463,17 @@ func (c *Child) signal(sig syscall.Signal) error {
 // NudgeRedraw asks the child to throw away any diff-based render state
 // and emit a full frame on the next tick. Used after a focus switch so
 // ratatui/ink TUIs re-render coherently against the snapshot we just
-// replayed. We toggle the PTY size by one row so the kernel reliably
-// emits SIGWINCH (TIOCSWINSZ skips the signal if the size didn't
-// change), then send SIGWINCH explicitly for TUIs that miss or coalesce
-// the size-toggled signal. The emulator is left alone — it already
-// matches our intended size and the brief mismatch only affects what the
-// child writes during the second redraw.
+// replayed. Sends an explicit SIGWINCH; TIOCSWINSZ with the same size
+// is a no-op in the kernel, so an explicit signal is what most TUIs
+// actually act on anyway. Avoid resize-toggles here — under a drag-
+// resize the kernel still emits intermediate SIGWINCHes against the
+// host PTY and toggling our child's size on top produces inconsistent
+// grid state.
 func (c *Child) NudgeRedraw(cols, rows uint16) {
 	pty := c.PTY()
 	if pty == nil || rows < 2 {
 		return
 	}
-	_ = pty.Resize(cols, rows-1)
-	_ = pty.Resize(cols, rows)
 	_ = c.signal(syscall.SIGWINCH)
 }
 

internal/app/cursorshift.go

@@ -67,6 +67,29 @@ func (cs *cursorShifter) clampCol(col int) int {
 	return col
 }
 
+// clampHostRow returns a host-coordinate row clamped to the viewport
+// rows mainTop..mainBottom. A child whose internal row state drifted
+// past the viewport (long-running claude / codex sessions) can issue a
+// CUP / HVP / VPA aimed at row hostRows; after the +rowOffset shift the
+// raw host target sits past the viewport bottom (the status row) or
+// above the viewport top (the tab bar). Without clamping the host
+// cursor lands on the chrome and the next printable wipes it. childRows
+// == 0 (uninitialised shifter, only seen in tests) disables clamping.
+func (cs *cursorShifter) clampHostRow(r int) int {
+	if cs.childRows <= 0 {
+		return r
+	}
+	minR := cs.rowOffset + 1
+	maxR := cs.rowOffset + cs.childRows
+	if r < minR {
+		return minR
+	}
+	if r > maxR {
+		return maxR
+	}
+	return r
+}
+
 // Shift consumes a chunk of PTY-master bytes, applies row offsets to
 // any complete CUP/HVP/VPA/DECSTBM sequences, and returns the rewritten
 // bytes. Partial sequences are buffered across calls so a CSI that
@@ -206,7 +229,7 @@ func (cs *cursorShifter) emitCSI() {
 			cs.pending.Write(cs.buf)
 			return
 		}
-		r += cs.rowOffset
+		r = cs.clampHostRow(r + cs.rowOffset)
 		c = cs.clampCol(c)
 		cs.pending.WriteString("\x1b[")
 		cs.pending.WriteString(strconv.Itoa(r))
@@ -226,13 +249,14 @@ func (cs *cursorShifter) emitCSI() {
 		cs.pending.WriteString(strconv.Itoa(c))
 		cs.pending.WriteByte(final)
 	case 'd':
-		// VPA: row.
+		// VPA: row. Clamp to the viewport so a child that drifted
+		// past its row count can't land the host cursor on the status row.
 		r, ok := parseOneParam(paramsRaw, 1)
 		if !ok {
 			cs.pending.Write(cs.buf)
 			return
 		}
-		r += cs.rowOffset
+		r = cs.clampHostRow(r + cs.rowOffset)
 		cs.pending.WriteString("\x1b[")
 		cs.pending.WriteString(strconv.Itoa(r))
 		cs.pending.WriteByte(final)

internal/app/cursorshift_test.go

@@ -111,3 +111,40 @@ func TestCursorShifterCUPNoClampWhenChildColsZero(t *testing.T) {
 		t.Fatalf("childCols=0 should disable col clamping: got %q", got)
 	}
 }
+
+// In longer claude sessions the cursor's internal row state could drift
+// past the viewport height. CUP / HVP / VPA without row clamping would
+// then land the host cursor on the status row or above the tab bar,
+// where the next printable wipes the chrome.
+func TestCursorShifterClampsCUPRowToMainBottom(t *testing.T) {
+	// rowOffset=2 (mainTop=3), childRows=36 → mainBottom=38.
+	cs := newCursorShifter(2, 36, 80)
+	got := cs.Shift([]byte("\x1b[40;5H"))
+	if string(got) != "\x1b[38;5H" {
+		t.Fatalf("CUP row 40 (post-shift 42) should clamp to 38: got %q", got)
+	}
+}
+
+func TestCursorShifterClampsHVPRowToMainBottom(t *testing.T) {
+	cs := newCursorShifter(2, 36, 80)
+	got := cs.Shift([]byte("\x1b[99;1f"))
+	if string(got) != "\x1b[38;1f" {
+		t.Fatalf("HVP row 99 should clamp to mainBottom: got %q", got)
+	}
+}
+
+func TestCursorShifterClampsVPARow(t *testing.T) {
+	cs := newCursorShifter(2, 36, 80)
+	got := cs.Shift([]byte("\x1b[60d"))
+	if string(got) != "\x1b[38d" {
+		t.Fatalf("VPA row 60 should clamp to mainBottom: got %q", got)
+	}
+}
+
+func TestCursorShifterCUPRowNoClampWhenChildRowsZero(t *testing.T) {
+	cs := newCursorShifter(2, 0, 80)
+	got := cs.Shift([]byte("\x1b[40;5H"))
+	if string(got) != "\x1b[42;5H" {
+		t.Fatalf("childRows=0 should disable row clamping: got %q", got)
+	}
+}

internal/app/host.go

@@ -378,7 +378,7 @@ func (h *toolHost) GetProcessOutput(callerID, processID, mode string, sinceOffse
 		return out, nil
 	case "stream":
 		b, end := c.StreamRead(sinceOffset)
-		out.Content = stripANSI(string(b))
+		out.Content = string(stripANSIBytes(nil, b))
 		out.NewOffset = end
 		return out, nil
 	default:
@@ -409,10 +409,10 @@ func (h *toolHost) SearchOutput(callerID, processID, pattern, kind string, limit
 		return mcp.SearchResult{}, mcp.Errorf(mcp.ErrorKindInvalidArgs, "regex: %v", err)
 	}
 	b, _ := c.StreamRead(0)
-	text := string(b)
 	if kind == "rendered" {
-		text = stripANSI(text)
+		b = stripANSIBytes(nil, b)
 	}
+	text := string(b)
 	lines := strings.Split(text, "\n")
 	matches := make([]mcp.SearchMatch, 0, limit)
 	truncated := false
@@ -440,10 +440,19 @@ func (h *toolHost) WaitForPattern(callerID, processID, pattern string, timeoutSe
 	if scope == "" {
 		scope = "grid"
 	}
+	if scope != "grid" && scope != "scrollback" {
+		return false, "", mcp.Errorf(mcp.ErrorKindInvalidArgs, "unknown scope %q (want grid|scrollback)", scope)
+	}
 	deadline := time.Now().Add(time.Duration(timeoutSeconds * float64(time.Second)))
-	tick := time.NewTicker(50 * time.Millisecond)
-	defer tick.Stop()
-	for {
+
+	// chunkWake fires on every PTY chunk for the target child. The
+	// fallback timer guarantees we still re-check on grid-only sweeps
+	// where the cursor position changed without a fresh chunk landing.
+	wake := newChunkNotifier(c.ID)
+	h.sess.Subscribe(wake)
+	defer h.sess.Unsubscribe(wake)
+
+	check := func() (bool, string) {
 		text := ""
 		switch scope {
 		case "grid":
@@ -454,23 +463,75 @@ func (h *toolHost) WaitForPattern(callerID, processID, pattern string, timeoutSe
 			}
 		case "scrollback":
 			b, _ := c.StreamRead(0)
-			text = stripANSI(string(b))
-		default:
-			return false, "", mcp.Errorf(mcp.ErrorKindInvalidArgs, "unknown scope %q (want grid|scrollback)", scope)
+			text = string(stripANSIBytes(nil, b))
 		}
 		if m := re.FindString(text); m != "" {
-			return true, m, nil
+			return true, m
 		}
-		if time.Now().After(deadline) {
+		return false, ""
+	}
+
+	if ok, m := check(); ok {
+		return true, m, nil
+	}
+	for {
+		remaining := time.Until(deadline)
+		if remaining <= 0 {
 			return false, "", nil
 		}
-		<-tick.C
+		// Long fallback tick — the chunk notifier wakes us promptly
+		// on fresh PTY output; the timer is only there for cases
+		// where grid state shifted without a new chunk.
+		wait := 500 * time.Millisecond
+		if remaining < wait {
+			wait = remaining
+		}
+		select {
+		case <-wake.fired:
+		case <-time.After(wait):
+		}
+		if ok, m := check(); ok {
+			return true, m, nil
+		}
 		if !c.IsLive() && c.Status() != StatusStopped {
 			return false, "", nil
 		}
 	}
 }
 
+// chunkNotifier is a one-shot-per-chunk wake channel listener.
+// Registers via Session.Subscribe; emits a non-blocking signal on
+// `fired` for every PTY chunk emitted by the target child. Used by
+// WaitForPattern to avoid 50ms-tick polling of the entire ring/grid.
+type chunkNotifier struct {
+	childID string
+	fired   chan struct{}
+}
+
+func newChunkNotifier(childID string) *chunkNotifier {
+	return &chunkNotifier{childID: childID, fired: make(chan struct{}, 1)}
+}
+
+func (n *chunkNotifier) OnChildSpawned(*Child) {}
+func (n *chunkNotifier) OnChildExited(c *Child) {
+	if c.ID != n.childID {
+		return
+	}
+	select {
+	case n.fired <- struct{}{}:
+	default:
+	}
+}
+func (n *chunkNotifier) OnPTYOut(id string, chunk []byte) {
+	if id != n.childID {
+		return
+	}
+	select {
+	case n.fired <- struct{}{}:
+	default:
+	}
+}
+
 func (h *toolHost) GetProcessPorts(callerID, processID string) ([]mcp.PortSighting, error) {
 	c := h.sess.FindChild(processID)
 	if c == nil {
@@ -887,6 +948,74 @@ func stripANSI(s string) string {
 	return ansiRegexp.ReplaceAllString(s, "")
 }
 
+// stripANSIBytes is the byte-slice form of stripANSI. Skips the
+// string conversion and the regex DFA — useful when the caller will
+// itself walk the result line-by-line (SearchOutput) or feed it to a
+// pattern match (WaitForPattern scrollback). Recognises the same
+// shapes the regex did:
+//   - `\x1b[ <params> <intermediate> <final-byte>` (CSI / SGR)
+//   - `\x1b<final-byte>` for `@..._` (one-byte escapes)
+//   - `\x07` (BEL)
+//
+// The dst slice is reused if cap is sufficient; the returned slice
+// is what callers should use.
+func stripANSIBytes(dst, src []byte) []byte {
+	if cap(dst) < len(src) {
+		dst = make([]byte, 0, len(src))
+	} else {
+		dst = dst[:0]
+	}
+	for i := 0; i < len(src); {
+		b := src[i]
+		if b == 0x07 {
+			i++
+			continue
+		}
+		if b != 0x1b {
+			dst = append(dst, b)
+			i++
+			continue
+		}
+		// ESC-led sequence.
+		if i+1 >= len(src) {
+			// Stranded ESC at end of buffer — drop it.
+			i++
+			continue
+		}
+		next := src[i+1]
+		if next != '[' {
+			// One-byte ESC sequence (`\x1b<final>` where final is
+			// `@..._` per the regex; we drop anything that follows).
+			if next >= 0x40 && next <= 0x5f {
+				i += 2
+				continue
+			}
+			// Anything else after ESC: drop the ESC, keep walking.
+			i++
+			continue
+		}
+		// CSI: parameters [0x30..0x3f]*, intermediate [0x20..0x2f]*,
+		// final [0x40..0x7e].
+		j := i + 2
+		for j < len(src) && src[j] >= 0x30 && src[j] <= 0x3f {
+			j++
+		}
+		for j < len(src) && src[j] >= 0x20 && src[j] <= 0x2f {
+			j++
+		}
+		if j < len(src) && src[j] >= 0x40 && src[j] <= 0x7e {
+			i = j + 1
+			continue
+		}
+		// Incomplete CSI — the regex form falls back to its
+		// `\x1b<final>` rule and matches `\x1b[` (`[` is 0x5b, inside
+		// 0x40..0x5f), consuming the two-byte prefix and leaving the
+		// pending params/intermediate bytes intact. Match that.
+		i += 2
+	}
+	return dst
+}
+
 // availableToolsForRole — SPEC §7 whoami exposes the list a caller can
 // invoke from its current role. Sub-agents lose `spawn_agent` (§8
 // two-level-tree rule).

internal/app/keymatch.go

@@ -40,6 +40,36 @@ type csiuKey struct {
 	event int
 }
 
+// parseSGRMouseWheel decodes the parameter run from an SGR-encoded
+// mouse press (`CSI < button ; col ; row M`) and returns a row delta
+// when the event is a scroll wheel. Wheel-up returns -wheelStep,
+// wheel-down returns +wheelStep. Modifier bits in the button code
+// (shift=4, alt=8, ctrl=16) are stripped before matching, so e.g.
+// shift+wheel still scrolls. Non-wheel buttons return false.
+func parseSGRMouseWheel(params []byte) (int, bool) {
+	const wheelStep = 3
+	// Button code runs up to the first ';'.
+	end := 0
+	for end < len(params) && params[end] != ';' {
+		end++
+	}
+	if end == 0 {
+		return 0, false
+	}
+	btn, err := strconv.Atoi(string(params[:end]))
+	if err != nil {
+		return 0, false
+	}
+	if btn&64 == 0 {
+		return 0, false
+	}
+	// Bit 0 selects up (0) vs down (1) for wheel events.
+	if btn&1 == 0 {
+		return -wheelStep, true
+	}
+	return wheelStep, true
+}
+
 // decodeCSIu parses the parameter string of a `CSI ... u` sequence.
 // The kitty shape is:
 //

internal/app/keymatch_test.go

@@ -39,6 +39,32 @@ func TestMatchCtrlK(t *testing.T) {
 	}
 }
 
+func TestParseSGRMouseWheel(t *testing.T) {
+	cases := []struct {
+		params string
+		want   int
+		ok     bool
+	}{
+		{"64;1;1", -3, true},  // wheel up
+		{"65;1;1", 3, true},   // wheel down
+		{"68;1;1", -3, true},  // shift+wheel up
+		{"69;1;1", 3, true},   // shift+wheel down
+		{"80;1;1", -3, true},  // ctrl+wheel up
+		{"81;1;1", 3, true},   // ctrl+wheel down
+		{"0;5;7", 0, false},   // left press
+		{"2;5;7", 0, false},   // right press
+		{"32;5;7", 0, false},  // drag
+		{"", 0, false},        // empty
+		{"abc;1;1", 0, false}, // garbage button
+	}
+	for _, c := range cases {
+		got, ok := parseSGRMouseWheel([]byte(c.params))
+		if ok != c.ok || got != c.want {
+			t.Errorf("parseSGRMouseWheel(%q) = (%d,%v), want (%d,%v)", c.params, got, ok, c.want, c.ok)
+		}
+	}
+}
+
 func TestMatchCtrlKConsecutive(t *testing.T) {
 	// Two kitty Ctrl-K sequences back to back, the chord case.
 	chunk := []byte("\x1b[107;5u\x1b[107;5u")

internal/app/launch.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/hjbdev/patterm/internal/persist"
 	"github.com/hjbdev/patterm/internal/preset"
 )
 
@@ -202,6 +203,33 @@ func (l *Launcher) LaunchCommandArgv(argv []string, displayName, parentID, workD
 	}, cols, rows)
 }
 
+// RestoreCommand re-spawns a persisted top-level command entry. If
+// the entry has a PresetRef and the preset still exists, the spawn
+// goes through LaunchCommandPreset (so preset.Env / WorkingDir stay
+// authoritative). Otherwise the saved argv runs directly via
+// LaunchCommandArgv with shell=false — entries that were originally
+// `shell: true` were already wrapped into `["sh","-lc",...]` before
+// persistence, so re-wrapping isn't needed.
+//
+// Returns the freshly minted Child. The caller is responsible for
+// setting auto-restart back on the returned entry.
+func (l *Launcher) RestoreCommand(e persist.Entry, presets preset.Set) (*Child, error) {
+	if e.PresetRef != "" {
+		for _, p := range presets.Processes {
+			if p.Name == e.PresetRef {
+				return l.LaunchCommandPreset(p, e.Name, "")
+			}
+		}
+		// Preset has been deleted since the entry was saved. Fall
+		// through to argv-based restore using whatever the saved
+		// command looked like at the time.
+	}
+	if len(e.Argv) == 0 {
+		return nil, fmt.Errorf("restore: entry %s has no argv", e.ID)
+	}
+	return l.LaunchCommandArgv(e.Argv, e.Name, "", e.WorkDir, nil, false)
+}
+
 // LaunchTerminal spawns a bare interactive shell. SPEC §7 kind=terminal.
 // argv defaults to $SHELL -i when empty.
 func (l *Launcher) LaunchTerminal(argv []string, displayName, parentID, workDir string, env []string) (*Child, error) {

internal/app/markdown.go

@@ -0,0 +1,483 @@
+package app
+
+import (
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// renderMarkdownLines turns a scratchpad's text into a slice of
+// terminal rows, each at most `cols` visible columns wide and ready to
+// paint (style codes included, trailing reset where needed, no
+// newline). The renderer covers the markdown subset most likely to
+// appear in scratchpad notes: headings (#, ##, ###), bold (**x**),
+// inline code (`x`), fenced code blocks (```), bullet/numbered lists,
+// blockquotes (> ), horizontal rules, and links rendered as their
+// text. Plain text passes through unchanged.
+func renderMarkdownLines(content string, cols int) []string {
+	if cols < 1 {
+		cols = 1
+	}
+	var out []string
+	inFence := false
+	for _, raw := range strings.Split(content, "\n") {
+		line := strings.TrimRight(raw, "\r")
+		trimmed := strings.TrimSpace(line)
+
+		if strings.HasPrefix(trimmed, "```") {
+			inFence = !inFence
+			out = append(out, mdFenceRule(cols))
+			continue
+		}
+		if inFence {
+			out = append(out, mdCodeBlockLines(line, cols)...)
+			continue
+		}
+		if trimmed == "" {
+			out = append(out, "")
+			continue
+		}
+		if isMDHRule(trimmed) {
+			out = append(out, styleBorder+strings.Repeat("─", cols)+styleReset)
+			continue
+		}
+		if body, level := parseMDHeading(line); level > 0 {
+			style := mdHeadingStyle(level)
+			out = append(out, wrapInline(parseInline(body), style, cols)...)
+			continue
+		}
+		if body, ok := parseBlockquote(line); ok {
+			prefix := styleAccent + "│ " + styleReset
+			lines := wrapInline(parseInline(body), styleHint, cols-2)
+			if len(lines) == 0 {
+				out = append(out, prefix)
+				continue
+			}
+			for _, l := range lines {
+				out = append(out, prefix+l)
+			}
+			continue
+		}
+		if marker, body, ok := parseListItem(line); ok {
+			prefix := mdBulletPrefix(marker)
+			indent := strings.Repeat(" ", mdVisibleLen(prefix))
+			lines := wrapInline(parseInline(body), "", cols-mdVisibleLen(prefix))
+			if len(lines) == 0 {
+				out = append(out, prefix)
+				continue
+			}
+			for i, l := range lines {
+				if i == 0 {
+					out = append(out, prefix+l)
+				} else {
+					out = append(out, indent+l)
+				}
+			}
+			continue
+		}
+		out = append(out, wrapInline(parseInline(line), "", cols)...)
+	}
+	return out
+}
+
+func mdHeadingStyle(level int) string {
+	switch level {
+	case 1:
+		return styleActive + styleBold
+	case 2:
+		return styleBold + styleAccent
+	default:
+		return styleBold
+	}
+}
+
+func mdBulletPrefix(marker string) string {
+	if isOrderedMarker(marker) {
+		return styleAccent + marker + " " + styleReset
+	}
+	return styleAccent + "• " + styleReset
+}
+
+func mdFenceRule(cols int) string {
+	if cols < 2 {
+		return styleBorder + strings.Repeat("─", cols) + styleReset
+	}
+	return styleBorder + strings.Repeat("─", cols) + styleReset
+}
+
+// mdCodeBlockLines emits one rendered row per (wrapped) source line
+// inside a fenced code block, prefixed with a thin accent gutter so the
+// block reads as one visual unit.
+func mdCodeBlockLines(line string, cols int) []string {
+	gutter := styleAccent + "│" + styleReset + " "
+	body := line
+	avail := cols - 2
+	if avail < 1 {
+		avail = 1
+	}
+	chunks := wrapPlain(body, avail)
+	if len(chunks) == 0 {
+		return []string{gutter}
+	}
+	out := make([]string, 0, len(chunks))
+	for _, c := range chunks {
+		out = append(out, gutter+"\x1b[38;5;180m"+c+styleReset)
+	}
+	return out
+}
+
+func isMDHRule(s string) bool {
+	if len(s) < 3 {
+		return false
+	}
+	c := s[0]
+	if c != '-' && c != '_' && c != '*' {
+		return false
+	}
+	for i := 0; i < len(s); i++ {
+		if s[i] != c && s[i] != ' ' {
+			return false
+		}
+	}
+	count := 0
+	for i := 0; i < len(s); i++ {
+		if s[i] == c {
+			count++
+		}
+	}
+	return count >= 3
+}
+
+func parseMDHeading(line string) (string, int) {
+	i := 0
+	for i < len(line) && line[i] == ' ' && i < 3 {
+		i++
+	}
+	level := 0
+	for i+level < len(line) && line[i+level] == '#' && level < 6 {
+		level++
+	}
+	if level == 0 {
+		return "", 0
+	}
+	rest := line[i+level:]
+	if rest != "" && rest[0] != ' ' {
+		return "", 0
+	}
+	return strings.TrimSpace(rest), level
+}
+
+func parseBlockquote(line string) (string, bool) {
+	t := strings.TrimLeft(line, " ")
+	if !strings.HasPrefix(t, ">") {
+		return "", false
+	}
+	rest := strings.TrimPrefix(t, ">")
+	rest = strings.TrimPrefix(rest, " ")
+	return rest, true
+}
+
+func parseListItem(line string) (marker, body string, ok bool) {
+	t := strings.TrimLeft(line, " ")
+	if len(t) >= 2 && (t[0] == '-' || t[0] == '*' || t[0] == '+') && t[1] == ' ' {
+		return string(t[0]), t[2:], true
+	}
+	// Ordered: digits then "." then space.
+	j := 0
+	for j < len(t) && t[j] >= '0' && t[j] <= '9' {
+		j++
+	}
+	if j > 0 && j+1 < len(t) && t[j] == '.' && t[j+1] == ' ' {
+		return t[:j+1], t[j+2:], true
+	}
+	return "", "", false
+}
+
+func isOrderedMarker(m string) bool {
+	if len(m) < 2 {
+		return false
+	}
+	if m[len(m)-1] != '.' {
+		return false
+	}
+	for i := 0; i < len(m)-1; i++ {
+		if m[i] < '0' || m[i] > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+// mdSpan is one styled run of plain text. style is an SGR prefix
+// applied at the start; the renderer emits styleReset between adjacent
+// spans of differing style and at end-of-line.
+type mdSpan struct {
+	text  string
+	style string
+}
+
+// parseInline turns one source line into styled spans. Recognises:
+//   - **bold** / __bold__ → bold span
+//   - `code` → inline code span
+//   - [text](url) → text rendered as accent+underline
+//
+// Unmatched delimiters are passed through as literal characters so a
+// stray `*` or backtick doesn't swallow the rest of the line.
+func parseInline(line string) []mdSpan {
+	var spans []mdSpan
+	var buf strings.Builder
+	flush := func(style string) {
+		if buf.Len() == 0 {
+			return
+		}
+		spans = append(spans, mdSpan{text: buf.String(), style: style})
+		buf.Reset()
+	}
+	i := 0
+	for i < len(line) {
+		c := line[i]
+		switch {
+		case c == '`':
+			if end := strings.IndexByte(line[i+1:], '`'); end >= 0 {
+				flush("")
+				spans = append(spans, mdSpan{text: line[i+1 : i+1+end], style: "\x1b[38;5;180m"})
+				i += end + 2
+				continue
+			}
+		case c == '*' && i+1 < len(line) && line[i+1] == '*':
+			if end := strings.Index(line[i+2:], "**"); end >= 0 {
+				flush("")
+				inner := parseInline(line[i+2 : i+2+end])
+				for _, s := range inner {
+					st := s.style
+					if st == "" {
+						st = styleBold
+					}
+					spans = append(spans, mdSpan{text: s.text, style: st})
+				}
+				i += end + 4
+				continue
+			}
+		case c == '_' && i+1 < len(line) && line[i+1] == '_':
+			if end := strings.Index(line[i+2:], "__"); end >= 0 {
+				flush("")
+				inner := parseInline(line[i+2 : i+2+end])
+				for _, s := range inner {
+					st := s.style
+					if st == "" {
+						st = styleBold
+					}
+					spans = append(spans, mdSpan{text: s.text, style: st})
+				}
+				i += end + 4
+				continue
+			}
+		case c == '[':
+			if close := strings.IndexByte(line[i+1:], ']'); close >= 0 {
+				rest := line[i+1+close+1:]
+				if strings.HasPrefix(rest, "(") {
+					if pclose := strings.IndexByte(rest[1:], ')'); pclose >= 0 {
+						flush("")
+						label := line[i+1 : i+1+close]
+						spans = append(spans, mdSpan{text: label, style: styleAccent + "\x1b[4m"})
+						i += 1 + close + 1 + 1 + pclose + 1
+						continue
+					}
+				}
+			}
+		}
+		buf.WriteByte(c)
+		i++
+	}
+	flush("")
+	return spans
+}
+
+// wrapInline lays out styled spans across one or more terminal rows of
+// `cols` visible columns each. Each output row is prefixed with
+// `lineStyle` so the caller can theme an entire wrapped paragraph
+// (headings, blockquotes) with one SGR. Wrapping prefers word
+// boundaries; oversized tokens hard-cut at the column boundary.
+func wrapInline(spans []mdSpan, lineStyle string, cols int) []string {
+	if cols < 1 {
+		cols = 1
+	}
+	var out []string
+	var b strings.Builder
+	written := 0
+	curStyle := ""
+
+	startLine := func() {
+		b.Reset()
+		written = 0
+		curStyle = ""
+		if lineStyle != "" {
+			b.WriteString(lineStyle)
+			curStyle = lineStyle
+		}
+	}
+	finishLine := func() {
+		if b.Len() == 0 && lineStyle == "" {
+			out = append(out, "")
+			return
+		}
+		b.WriteString(styleReset)
+		out = append(out, b.String())
+	}
+
+	startLine()
+	writeChar := func(r rune, st string) {
+		if curStyle != st {
+			b.WriteString(styleReset)
+			if lineStyle != "" {
+				b.WriteString(lineStyle)
+			}
+			if st != "" {
+				b.WriteString(st)
+			}
+			curStyle = st
+		}
+		b.WriteRune(r)
+		written += runeCellWidth(r)
+	}
+
+	for _, sp := range spans {
+		st := sp.style
+		// Tokenize span into words+spaces for word-boundary wrapping.
+		text := sp.text
+		for len(text) > 0 {
+			r, size := utf8.DecodeRuneInString(text)
+			// Take a run of either spaces or non-spaces.
+			isSpace := unicode.IsSpace(r)
+			j := 0
+			w := 0
+			for j < len(text) {
+				rr, sz := utf8.DecodeRuneInString(text[j:])
+				if unicode.IsSpace(rr) != isSpace {
+					break
+				}
+				j += sz
+				w += runeCellWidth(rr)
+			}
+			tok := text[:j]
+			text = text[j:]
+			_ = r
+			_ = size
+
+			if isSpace {
+				if written == 0 {
+					// Drop leading whitespace at line start.
+					continue
+				}
+				if written+w > cols {
+					finishLine()
+					startLine()
+					continue
+				}
+				for _, rr := range tok {
+					writeChar(rr, st)
+				}
+				continue
+			}
+			// Non-space token. If it fits, append; else wrap.
+			if w <= cols {
+				if written+w > cols {
+					// Trim trailing spaces written so far before wrap.
+					finishLine()
+					startLine()
+				}
+				for _, rr := range tok {
+					writeChar(rr, st)
+				}
+				continue
+			}
+			// Token longer than a full row: hard-cut.
+			for _, rr := range tok {
+				cw := runeCellWidth(rr)
+				if written+cw > cols {
+					finishLine()
+					startLine()
+				}
+				writeChar(rr, st)
+			}
+		}
+	}
+	finishLine()
+	if len(out) == 0 {
+		out = append(out, "")
+	}
+	return out
+}
+
+// wrapPlain wraps a literal string (no styling) at a `cols` visible
+// column budget. Used by code-block rendering, which preserves the raw
+// line verbatim.
+func wrapPlain(line string, cols int) []string {
+	if cols < 1 {
+		cols = 1
+	}
+	if line == "" {
+		return []string{""}
+	}
+	var out []string
+	var b strings.Builder
+	written := 0
+	for _, r := range line {
+		w := runeCellWidth(r)
+		if written+w > cols {
+			out = append(out, b.String())
+			b.Reset()
+			written = 0
+		}
+		b.WriteRune(r)
+		written += w
+	}
+	if b.Len() > 0 {
+		out = append(out, b.String())
+	}
+	return out
+}
+
+// runeCellWidth is a tiny approximation of terminal cell width: 0 for
+// non-printables, 1 for the common case. Wide East-Asian and emoji
+// runes would ideally be 2, but pads in practice are Latin/symbol text;
+// landing a precise width walk is left for when we see a real case.
+func runeCellWidth(r rune) int {
+	if r == 0 || r == '\r' || r == '\n' {
+		return 0
+	}
+	if r < 0x20 || r == 0x7f {
+		return 0
+	}
+	return 1
+}
+
+// mdVisibleLen counts visible columns in a string with embedded SGR
+// escapes — the inverse of the writer that produces them.
+func mdVisibleLen(s string) int {
+	n := 0
+	i := 0
+	for i < len(s) {
+		if s[i] == 0x1b {
+			j := i + 1
+			if j < len(s) && s[j] == '[' {
+				j++
+				for j < len(s) && !isCSIFinal(s[j]) {
+					j++
+				}
+				if j < len(s) {
+					j++
+				}
+				i = j
+				continue
+			}
+			i = j
+			continue
+		}
+		r, size := utf8.DecodeRuneInString(s[i:])
+		n += runeCellWidth(r)
+		i += size
+	}
+	return n
+}
+

internal/app/markdown_test.go

@@ -0,0 +1,93 @@
+package app
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestRenderMarkdownLines_Heading(t *testing.T) {
+	lines := renderMarkdownLines("# Hello", 40)
+	if len(lines) != 1 {
+		t.Fatalf("heading should be 1 line, got %d (%v)", len(lines), lines)
+	}
+	if !strings.Contains(lines[0], "Hello") {
+		t.Errorf("heading text missing: %q", lines[0])
+	}
+	if !strings.Contains(lines[0], "\x1b[1m") {
+		t.Errorf("heading not bold: %q", lines[0])
+	}
+}
+
+func TestRenderMarkdownLines_BulletWrapping(t *testing.T) {
+	src := "- alpha beta gamma delta epsilon"
+	lines := renderMarkdownLines(src, 14)
+	if len(lines) < 2 {
+		t.Fatalf("expected wrap into 2+ lines, got %d: %v", len(lines), lines)
+	}
+	if !strings.Contains(lines[0], "•") {
+		t.Errorf("first line should carry bullet, got %q", lines[0])
+	}
+	if strings.Contains(lines[1], "•") {
+		t.Errorf("continuation should not repeat bullet: %q", lines[1])
+	}
+}
+
+func TestRenderMarkdownLines_InlineCode(t *testing.T) {
+	lines := renderMarkdownLines("call `foo()` now", 40)
+	if len(lines) != 1 {
+		t.Fatalf("expected one line, got %d", len(lines))
+	}
+	if !strings.Contains(lines[0], "foo()") {
+		t.Errorf("inline code text missing: %q", lines[0])
+	}
+	if !strings.Contains(lines[0], "\x1b[38;5;180m") {
+		t.Errorf("inline code style missing: %q", lines[0])
+	}
+}
+
+func TestRenderMarkdownLines_FencedCode(t *testing.T) {
+	src := "before\n```\nfn main() {\n}\n```\nafter"
+	lines := renderMarkdownLines(src, 40)
+	// Two fence rules + two code rows + before + after = at least 5 lines.
+	if len(lines) < 5 {
+		t.Fatalf("expected fenced block to produce >=5 rows, got %d: %v", len(lines), lines)
+	}
+	foundCode := false
+	for _, l := range lines {
+		if strings.Contains(l, "fn main()") {
+			foundCode = true
+			break
+		}
+	}
+	if !foundCode {
+		t.Errorf("code block content missing from output: %v", lines)
+	}
+}
+
+func TestRenderMarkdownLines_HardWrap(t *testing.T) {
+	src := strings.Repeat("a", 50)
+	lines := renderMarkdownLines(src, 10)
+	if len(lines) < 5 {
+		t.Fatalf("expected long line to wrap into >=5 rows, got %d: %v", len(lines), lines)
+	}
+}
+
+func TestRenderMarkdownLines_PreservesBlankLines(t *testing.T) {
+	src := "para1\n\npara2"
+	lines := renderMarkdownLines(src, 40)
+	if len(lines) != 3 {
+		t.Fatalf("expected 3 rows, got %d: %v", len(lines), lines)
+	}
+	if lines[1] != "" {
+		t.Errorf("middle row should be empty, got %q", lines[1])
+	}
+}
+
+func TestMDVisibleLen(t *testing.T) {
+	if got := mdVisibleLen("\x1b[1mfoo\x1b[0m"); got != 3 {
+		t.Errorf("mdVisibleLen styled: want 3 got %d", got)
+	}
+	if got := mdVisibleLen("hello"); got != 5 {
+		t.Errorf("mdVisibleLen plain: want 5 got %d", got)
+	}
+}

internal/app/ring_test.go

@@ -0,0 +1,106 @@
+package app
+
+import (
+	"bytes"
+	"testing"
+)
+
+func newRingChild() *Child {
+	return newChildEntry("id", "name", KindCommand, nil, nil, "", "", "")
+}
+
+func TestRingShortWrite(t *testing.T) {
+	c := newRingChild()
+	c.recordWrite([]byte("hello"))
+	b, end := c.StreamRead(0)
+	if end != 5 {
+		t.Fatalf("end=%d want 5", end)
+	}
+	if string(b) != "hello" {
+		t.Fatalf("got %q want %q", b, "hello")
+	}
+	// Read past the head returns nil, same end.
+	b, end = c.StreamRead(5)
+	if end != 5 || b != nil {
+		t.Fatalf("re-read: end=%d b=%v", end, b)
+	}
+}
+
+func TestRingIncrementalRead(t *testing.T) {
+	c := newRingChild()
+	c.recordWrite([]byte("abc"))
+	c.recordWrite([]byte("def"))
+	b, end := c.StreamRead(3)
+	if end != 6 || string(b) != "def" {
+		t.Fatalf("got %q end=%d", b, end)
+	}
+}
+
+func TestRingWrapAround(t *testing.T) {
+	c := newRingChild()
+	// Write more than ringCap to force wrap. Use a pattern we can
+	// verify: bytes equal to (i mod 256).
+	total := ringCap + 1000
+	src := make([]byte, total)
+	for i := range src {
+		src[i] = byte(i)
+	}
+	// Write in pieces to exercise the wrap copy in recordWrite.
+	for i := 0; i < total; i += 7777 {
+		end := i + 7777
+		if end > total {
+			end = total
+		}
+		c.recordWrite(src[i:end])
+	}
+	// The freshest ringCap bytes should be readable.
+	b, head := c.StreamRead(0)
+	if head != int64(total) {
+		t.Fatalf("head=%d want %d", head, total)
+	}
+	if len(b) != ringCap {
+		t.Fatalf("len(b)=%d want %d", len(b), ringCap)
+	}
+	want := src[total-ringCap:]
+	if !bytes.Equal(b, want) {
+		t.Fatalf("ring contents diverge from source tail")
+	}
+}
+
+func TestRingChunkLargerThanCap(t *testing.T) {
+	c := newRingChild()
+	src := make([]byte, ringCap+500)
+	for i := range src {
+		src[i] = byte(i + 1)
+	}
+	c.recordWrite(src)
+	b, head := c.StreamRead(0)
+	if head != int64(len(src)) {
+		t.Fatalf("head=%d want %d", head, len(src))
+	}
+	if len(b) != ringCap {
+		t.Fatalf("len(b)=%d want %d", len(b), ringCap)
+	}
+	if !bytes.Equal(b, src[500:]) {
+		t.Fatalf("ring tail mismatch")
+	}
+}
+
+func TestStripANSIBytesEquivalence(t *testing.T) {
+	cases := []string{
+		"hello world",
+		"\x1b[31mred\x1b[0m text",
+		"line1\nline2\r\nline3",
+		"bell\x07ish",
+		"weird \x1bA escape",
+		"truncated \x1b[1;",
+		"",
+	}
+	for _, in := range cases {
+		want := stripANSI(in)
+		got := string(stripANSIBytes(nil, []byte(in)))
+		if got != want {
+			t.Errorf("stripANSIBytes(%q) = %q want %q", in, got, want)
+		}
+	}
+}

internal/app/session.go

@@ -12,9 +12,11 @@ import (
 	"fmt"
 	"os"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 
+	"github.com/hjbdev/patterm/internal/persist"
 	"github.com/hjbdev/patterm/internal/vt"
 )
 
@@ -38,8 +40,25 @@ type Session struct {
 
 	// listeners is the set of UI listeners that want to hear about child
 	// lifecycle events (spawn/exit) — exactly one (the TUI) in v1.
+	// listeners is an atomic.Pointer to a frozen slice. Subscribe
+	// copy-on-writes the slice; emit* paths use a single atomic Load.
+	// This drops one mutex acquisition per PTY chunk on the hot path.
 	listenersMu sync.Mutex
-	listeners   []ChildEventListener
+	listeners   atomic.Pointer[[]ChildEventListener]
+
+	// persistStore records top-level command entries to a per-project
+	// JSON file so they can be re-spawned after patterm restarts.
+	// Optional; nil means "no persistence" (used by unit tests).
+	persistStore *persist.Store
+}
+
+// SetPersistStore attaches a process-persistence store. Future Spawn /
+// Close / Rename / SetAutoRestart calls on top-level command entries
+// will mirror the change into the store.
+func (s *Session) SetPersistStore(p *persist.Store) {
+	s.mu.Lock()
+	s.persistStore = p
+	s.mu.Unlock()
 }
 
 // ChildEventListener is implemented by the TUI to react to lifecycle
@@ -65,32 +84,58 @@ func NewSession(projectDir, projectKey string) *Session {
 func (s *Session) Subscribe(l ChildEventListener) {
 	s.listenersMu.Lock()
 	defer s.listenersMu.Unlock()
-	s.listeners = append(s.listeners, l)
+	prev := s.listenersSnapshot()
+	next := make([]ChildEventListener, 0, len(prev)+1)
+	next = append(next, prev...)
+	next = append(next, l)
+	s.listeners.Store(&next)
+}
+
+// Unsubscribe removes a previously-registered listener. Safe to call
+// with a listener that wasn't registered (no-op).
+func (s *Session) Unsubscribe(l ChildEventListener) {
+	s.listenersMu.Lock()
+	defer s.listenersMu.Unlock()
+	prev := s.listenersSnapshot()
+	if len(prev) == 0 {
+		return
+	}
+	next := make([]ChildEventListener, 0, len(prev))
+	for _, e := range prev {
+		if e != l {
+			next = append(next, e)
+		}
+	}
+	s.listeners.Store(&next)
+}
+
+// listenersSnapshot returns the frozen listener slice. Safe to call
+// without the listeners mutex.
+func (s *Session) listenersSnapshot() []ChildEventListener {
+	p := s.listeners.Load()
+	if p == nil {
+		return nil
+	}
+	return *p
 }
 
 func (s *Session) emitSpawn(c *Child) {
-	s.listenersMu.Lock()
-	ls := append([]ChildEventListener(nil), s.listeners...)
-	s.listenersMu.Unlock()
-	for _, l := range ls {
+	for _, l := range s.listenersSnapshot() {
 		l.OnChildSpawned(c)
 	}
 }
 
 func (s *Session) emitExit(c *Child) {
-	s.listenersMu.Lock()
-	ls := append([]ChildEventListener(nil), s.listeners...)
-	s.listenersMu.Unlock()
-	for _, l := range ls {
+	for _, l := range s.listenersSnapshot() {
 		l.OnChildExited(c)
 	}
 }
 
+// emitPTYOut dispatches a fresh PTY chunk to every listener. Listeners
+// MUST NOT retain `chunk` past return — the slice is owned by the
+// pumpChild read buffer and is overwritten on the next read.
 func (s *Session) emitPTYOut(id string, chunk []byte) {
-	s.listenersMu.Lock()
-	ls := append([]ChildEventListener(nil), s.listeners...)
-	s.listenersMu.Unlock()
-	for _, l := range ls {
+	for _, l := range s.listenersSnapshot() {
 		l.OnPTYOut(id, chunk)
 	}
 }
@@ -162,14 +207,67 @@ func (s *Session) Spawn(spec SpawnSpec, cols, rows uint16) (*Child, error) {
 	s.mu.Lock()
 	s.children[id] = c
 	s.order = append(s.order, id)
+	store := s.persistStore
 	s.mu.Unlock()
 
+	// Wire persistence callback BEFORE registering so SetName /
+	// SetAutoRestart calls that race the listener still hit the store.
+	if store != nil {
+		c.setPersistFn(func(ch *Child) {
+			s.persistEntry(ch)
+		})
+		s.persistEntry(c)
+	}
+
 	s.emitSpawn(c)
 	go s.pumpChild(c, runID)
 	go s.reapChild(c, runID)
 	return c, nil
 }
 
+// persistEntry writes (or refreshes) the persist record for c if it
+// qualifies — top-level command entries only. No-op when no store is
+// attached.
+func (s *Session) persistEntry(c *Child) {
+	s.mu.Lock()
+	store := s.persistStore
+	s.mu.Unlock()
+	if store == nil || !shouldPersist(c) {
+		return
+	}
+	e := persist.Entry{
+		ID:          c.ID,
+		Name:        c.DisplayName(),
+		Argv:        append([]string(nil), c.Argv...),
+		WorkDir:     c.WorkDir,
+		PresetRef:   c.PresetRef,
+		AutoRestart: c.AutoRestart(),
+	}
+	if err := store.Save(e); err != nil {
+		logf("persist save %s: %v", c.ID, err)
+	}
+}
+
+func (s *Session) forgetPersisted(id string) {
+	s.mu.Lock()
+	store := s.persistStore
+	s.mu.Unlock()
+	if store == nil {
+		return
+	}
+	if err := store.Remove(id); err != nil {
+		logf("persist remove %s: %v", id, err)
+	}
+}
+
+// shouldPersist gates which Child entries get mirrored into the
+// persist store. v1 only restores top-level command entries — agents
+// and terminals are ephemeral by design, and sub-agent-spawned
+// commands belong to their orchestrator's lifecycle.
+func shouldPersist(c *Child) bool {
+	return c != nil && c.Kind == KindCommand && c.ParentID == ""
+}
+
 // Start (re)attaches a PTY to an entry that is currently stopped or
 // exited. Errors if the entry is already live.
 func (s *Session) Start(id string, cols, rows uint16) error {
@@ -238,6 +336,7 @@ func (s *Session) Close(id string, sig syscall.Signal) error {
 		}
 	}
 	s.mu.Unlock()
+	s.forgetPersisted(id)
 	return nil
 }
 
@@ -257,6 +356,12 @@ func (s *Session) pumpChild(c *Child, runID uint64) {
 	if pty == nil {
 		return
 	}
+	// One PTY read buffer per pump goroutine. Consumers downstream
+	// (em.Write is synchronous through CGO; recordWrite append-copies
+	// into the ring; renderer.Render copies into its pending buffer)
+	// all complete or copy before returning, so the buffer can be
+	// reused without aliasing live data. See ChildEventListener.OnPTYOut
+	// docstring — listeners must not retain `chunk`.
 	buf := make([]byte, 64*1024)
 	for {
 		n, err := pty.Read(buf)
@@ -264,8 +369,7 @@ func (s *Session) pumpChild(c *Child, runID uint64) {
 			if !c.isCurrentRun(runID) {
 				return
 			}
-			chunk := make([]byte, n)
-			copy(chunk, buf[:n])
+			chunk := buf[:n]
 			if em := c.Emulator(); em != nil {
 				if _, werr := em.Write(chunk); werr != nil {
 					logf("emulator.Write(child %s): %v", c.ID, werr)

internal/app/sidebar.go

@@ -22,6 +22,7 @@ func (st *uiState) drawSidebar() {
 	st.mu.Lock()
 	palOpen := st.palette != nil
 	focus := st.focusedID
+	focusPad := st.focusedPad
 	activeAgent := st.activeAgentID
 	st.mu.Unlock()
 	if palOpen {
@@ -130,30 +131,24 @@ func (st *uiState) drawSidebar() {
 		write(line)
 	}
 
-	// Scratchpads list — pick the most-recently-modified one as the
-	// preview target. SPEC §4.
-	var previewName string
+	// Scratchpads list — names only. The preview pane used to live
+	// here and clobbered the main viewport when content overflowed the
+	// rail. Focus moves to a pad via Ctrl+W/S; the content renders in
+	// the main viewport via repaintFocusedPad. SPEC §4.
 	if row+2 <= maxRow {
 		write("")
 		writeHeader("Scratchpads")
-		entries, err := st.pads.List()
-		if err == nil {
+		entries := st.padsList()
+		if entries != nil {
 			if len(entries) == 0 {
 				write("   " + styleDim + "(none)" + styleReset)
 			} else {
-				var newestTS string
-				for _, e := range entries {
-					if e.ModifiedAt > newestTS {
-						newestTS = e.ModifiedAt
-						previewName = e.Name
-					}
-				}
 				for _, e := range entries {
 					if row > maxRow {
 						break
 					}
 					var line string
-					if e.Name == previewName {
+					if e.Name == focusPad {
 						line = " " + styleAccent + "▎" + styleReset + " " +
 							styleBold + e.Name + styleReset
 					} else {
@@ -165,22 +160,6 @@ func (st *uiState) drawSidebar() {
 		}
 	}
 
-	// Preview pane: dim file content under a thin divider.
-	if previewName != "" && row+2 <= maxRow {
-		write("")
-		write(" " + styleBorder + strings.Repeat("─", width-2) + styleReset)
-		write(" " + styleActive + previewName + styleReset)
-		content, _, err := st.pads.Read(previewName)
-		if err == nil {
-			for _, line := range strings.Split(content, "\n") {
-				if row > maxRow {
-					break
-				}
-				write(" " + styleDim + line + styleReset)
-			}
-		}
-	}
-
 	// Blank-fill any rows the rail content didn't cover so stale
 	// content from a previous redraw doesn't linger.
 	for row <= maxRow {

internal/app/tree.go

@@ -1,5 +1,19 @@
 package app
 
+import "github.com/hjbdev/patterm/internal/scratchpad"
+
+// navEntry is one row in the unified sidebar navigation list. Exactly
+// one of childID or pad is set. childID points at a Child by ID; pad
+// names a scratchpad entry. Empty zero-value means "no target".
+type navEntry struct {
+	childID string
+	pad     string
+}
+
+func (n navEntry) empty() bool   { return n.childID == "" && n.pad == "" }
+func (n navEntry) isPad() bool   { return n.pad != "" }
+func (n navEntry) isChild() bool { return n.childID != "" }
+
 // visibleAgentTree returns the running entries under the active agent
 // tab (root agent + its sub-agents). With the new Processes pane,
 // command processes live in their own section and never show up here —
@@ -200,9 +214,66 @@ func sidebarNavList(children []*Child, activeAgentID string) []*Child {
 	return out
 }
 
-// nextChildID returns the id `step` positions away from the current
-// focus in the combined Processes + active-agent-tree navigation list,
-// wrapping at both ends. Empty when there's nothing else to land on.
+// sidebarNav returns the combined Processes + Agent Tree + Scratchpads
+// navigation list. Scratchpads always appear after children so the
+// existing "step past the tree" expectation still holds.
+func sidebarNav(children []*Child, activeAgentID string, pads []scratchpad.Entry) []navEntry {
+	flat := sidebarNavList(children, activeAgentID)
+	out := make([]navEntry, 0, len(flat)+len(pads))
+	for _, c := range flat {
+		out = append(out, navEntry{childID: c.ID})
+	}
+	for _, p := range pads {
+		out = append(out, navEntry{pad: p.Name})
+	}
+	return out
+}
+
+// nextNavEntry returns the entry `step` positions away from the
+// current focus in the unified nav list. Either focusChildID or
+// focusPad will be set (or both empty for "nothing focused yet").
+// Empty when there's nothing else to land on.
+func nextNavEntry(children []*Child, focusChildID, focusPad, activeAgentID string, pads []scratchpad.Entry, step int) navEntry {
+	flat := sidebarNav(children, activeAgentID, pads)
+	if len(flat) == 0 {
+		return navEntry{}
+	}
+	matches := func(e navEntry) bool {
+		if focusPad != "" && e.pad != "" {
+			return e.pad == focusPad
+		}
+		if focusChildID != "" && e.childID != "" {
+			return e.childID == focusChildID
+		}
+		return false
+	}
+	if len(flat) == 1 {
+		if matches(flat[0]) {
+			return navEntry{}
+		}
+		return flat[0]
+	}
+	idx := -1
+	for i, e := range flat {
+		if matches(e) {
+			idx = i
+			break
+		}
+	}
+	if idx < 0 {
+		idx = 0
+	}
+	idx = (idx + step) % len(flat)
+	if idx < 0 {
+		idx += len(flat)
+	}
+	if matches(flat[idx]) {
+		return navEntry{}
+	}
+	return flat[idx]
+}
+
+// nextChildID is retained for tests; it ignores scratchpads.
 func nextChildID(children []*Child, focusID, activeAgentID string, step int) string {
 	flat := sidebarNavList(children, activeAgentID)
 	if len(flat) == 0 {

internal/app/viewport_renderer.go

@@ -17,6 +17,8 @@ type viewportRenderer struct {
 	col          int
 	scrollTop    int
 	scrollBottom int
+	originMode   bool
+	lrMarginMode bool
 
 	state   viewportState
 	buf     []byte
@@ -75,8 +77,40 @@ func (vr *viewportRenderer) Render(in []byte) []byte {
 	vr.mu.Lock()
 	defer vr.mu.Unlock()
 	vr.pending.Reset()
-	for _, b := range in {
-		vr.feed(b)
+	// Fast path: while we're in vpNormal and have a run of plain ASCII
+	// printables that fit the remaining column budget, copy en bloc
+	// instead of round-tripping each byte through the feed state
+	// machine. UTF-8 leaders and any control byte fall back to the
+	// per-byte path so the cursor/skipUTF8/clamp logic stays exact.
+	for i := 0; i < len(in); {
+		if vr.state == vpNormal {
+			maxCol := int(vr.layout.childCols())
+			if maxCol > 0 && vr.col >= 1 && vr.col <= maxCol {
+				budget := maxCol - vr.col + 1
+				j := i
+				for j < len(in) && budget > 0 {
+					b := in[j]
+					// Pure ASCII printables only — any control byte
+					// (0x1b ESC included), UTF-8 leader, or trailer
+					// kicks back to the state machine.
+					if b < 0x20 || b == 0x7f || b >= 0x80 {
+						break
+					}
+					j++
+					budget--
+				}
+				if j-i >= 4 {
+					vr.pending.Write(in[i:j])
+					vr.col += j - i
+					vr.skipUTF8 = false
+					vr.clampCursor()
+					i = j
+					continue
+				}
+			}
+		}
+		vr.feed(in[i])
+		i++
 	}
 	return []byte(vr.pending.String())
 }
@@ -192,12 +226,53 @@ func (vr *viewportRenderer) emitCSI() {
 	params := vr.buf[2 : len(vr.buf)-1]
 
 	if final == 'h' || final == 'l' {
+		if isOriginMode(params) {
+			vr.setOriginMode(final == 'h')
+			vr.emitCursorPosition(vr.row, vr.col)
+			return
+		}
+		if isLeftRightMarginMode(params) {
+			vr.lrMarginMode = final == 'h'
+			return
+		}
 		if isAltScreenMode(params) {
 			return
 		}
+		if isMouseTrackingMode(params) {
+			// Patterm owns mouse reporting on the host so wheel events keep
+			// flowing for scroll-viewport. The child's own emulator still
+			// observes the mode set/reset (it processes the same bytes we
+			// hand to ghostty_terminal_vt_write), so we know whether the
+			// child wants mouse input — we just don't let it disarm our
+			// host listener.
+			return
+		}
+	}
+
+	if final == 's' && vr.lrMarginMode {
+		return
 	}
 
 	switch final {
+	case 'H', 'f':
+		r, c, ok := parseTwoParams(params)
+		if !ok {
+			vr.pending.Write(vr.shifter.Shift(vr.buf))
+			return
+		}
+		vr.row = vr.originRow(r)
+		vr.col = c
+		vr.emitCursorPosition(vr.row, c)
+		vr.clampCursor()
+	case 'd':
+		r, ok := parseOneParam(params, 1)
+		if !ok {
+			vr.pending.Write(vr.shifter.Shift(vr.buf))
+			return
+		}
+		vr.row = vr.originRow(r)
+		vr.pending.Write(vr.shifter.Shift([]byte(fmt.Sprintf("\x1b[%dd", vr.row))))
+		vr.clampCursor()
 	case 'J':
 		n, ok := parseOneParam(params, 0)
 		if !ok {
@@ -230,10 +305,85 @@ func (vr *viewportRenderer) emitCSI() {
 		// the sidebar is repainted afterwards.
 		vr.pending.Write(vr.shifter.Shift(vr.buf))
 		vr.scrolled = true
+	case 'r':
+		vr.pending.Write(vr.shifter.Shift(vr.buf))
+		if vr.trackScrollRegion(params) {
+			vr.emitHomeAfterScrollRegion()
+		}
+	case 'A', 'B', 'E', 'F':
+		// Relative cursor moves: CUU (A) / CUD (B) / CNL (E) / CPL (F).
+		// The cursor shifter only rewrites absolute positioning, so a
+		// child that asks the cursor to "go up 50" from viewport row 1
+		// would walk the host cursor into the tab bar (and the next
+		// printable would write there). Clamp the step using the
+		// renderer's tracked row so the host cursor stays inside the
+		// viewport. E / F additionally home the column to 1.
+		vr.emitRelativeRowMove(final, params)
+		return
 	default:
 		vr.pending.Write(vr.shifter.Shift(vr.buf))
 	}
-	vr.trackCSI(final, params)
+	if final != 'H' && final != 'f' && final != 'd' && final != 'r' {
+		vr.trackCSI(final, params)
+	}
+}
+
+// emitRelativeRowMove rewrites CSI A / B / E / F so the resulting host
+// cursor stays within rows 1..childRows in viewport coordinates. The
+// renderer already tracks vr.row for clear-line bookkeeping; reusing
+// that here avoids a second cursor model. n is normalized — a step of
+// 0 is treated as 1 to match xterm. After clamping, if the effective
+// step is zero we drop the sequence (the cursor is already pinned to
+// the boundary). E / F also move the cursor to column 1 even when no
+// row step is emitted.
+func (vr *viewportRenderer) emitRelativeRowMove(final byte, params []byte) {
+	n, ok := parseOneParam(params, 1)
+	if !ok {
+		vr.pending.Write(vr.shifter.Shift(vr.buf))
+		return
+	}
+	if n <= 0 {
+		n = 1
+	}
+	rows := int(vr.layout.childRows())
+	if rows < 1 {
+		rows = 1
+	}
+	row := vr.row
+	if row < 1 {
+		row = 1
+	}
+	if row > rows {
+		row = rows
+	}
+	up := final == 'A' || final == 'F'
+	var safe int
+	if up {
+		safe = row - 1
+	} else {
+		safe = rows - row
+	}
+	if safe < 0 {
+		safe = 0
+	}
+	if n > safe {
+		n = safe
+	}
+	if n > 0 {
+		if up {
+			vr.row -= n
+		} else {
+			vr.row += n
+		}
+		fmt.Fprintf(&vr.pending, "\x1b[%d%c", n, final)
+	}
+	if final == 'E' || final == 'F' {
+		// CNL / CPL anchor the column at 1 regardless of whether the
+		// row step was clamped to zero, matching xterm.
+		vr.col = 1
+		vr.pending.WriteByte('\r')
+	}
+	vr.clampCursor()
 }
 
 func isAltScreenMode(params []byte) bool {
@@ -250,6 +400,52 @@ func isAltScreenMode(params []byte) bool {
 	return false
 }
 
+func isOriginMode(params []byte) bool {
+	s := string(params)
+	if !strings.HasPrefix(s, "?") {
+		return false
+	}
+	for _, p := range strings.Split(strings.TrimPrefix(s, "?"), ";") {
+		if p == "6" {
+			return true
+		}
+	}
+	return false
+}
+
+func isLeftRightMarginMode(params []byte) bool {
+	s := string(params)
+	if !strings.HasPrefix(s, "?") {
+		return false
+	}
+	for _, p := range strings.Split(strings.TrimPrefix(s, "?"), ";") {
+		if p == "69" {
+			return true
+		}
+	}
+	return false
+}
+
+// isMouseTrackingMode reports whether any of the modes in a CSI ? … h/l
+// is a mouse-tracking or mouse-encoding DEC private mode. The host runs
+// with SGR mouse reporting permanently armed; we drop the child's set/
+// reset for these modes from the host stream so wheel events keep
+// reaching patterm.
+func isMouseTrackingMode(params []byte) bool {
+	s := string(params)
+	if !strings.HasPrefix(s, "?") {
+		return false
+	}
+	for _, p := range strings.Split(strings.TrimPrefix(s, "?"), ";") {
+		switch p {
+		case "9", "1000", "1001", "1002", "1003", "1004",
+			"1005", "1006", "1007", "1015", "1016":
+			return true
+		}
+	}
+	return false
+}
+
 func (vr *viewportRenderer) clearViewport() string {
 	var b strings.Builder
 	b.WriteString("\x1b7")
@@ -339,6 +535,53 @@ func (vr *viewportRenderer) resetScrollRegion() {
 	}
 }
 
+func (vr *viewportRenderer) setOriginMode(on bool) {
+	vr.originMode = on
+	if on {
+		vr.row = vr.scrollTop
+	} else {
+		vr.row = 1
+	}
+	vr.col = 1
+	vr.clampCursor()
+}
+
+func (vr *viewportRenderer) originRow(row int) int {
+	if row < 1 {
+		row = 1
+	}
+	if !vr.originMode {
+		return row
+	}
+	row = vr.scrollTop + row - 1
+	if row < vr.scrollTop {
+		row = vr.scrollTop
+	}
+	if row > vr.scrollBottom {
+		row = vr.scrollBottom
+	}
+	return row
+}
+
+func (vr *viewportRenderer) homeAfterScrollRegion() {
+	if vr.originMode {
+		vr.row = vr.scrollTop
+	} else {
+		vr.row = 1
+	}
+	vr.col = 1
+	vr.clampCursor()
+}
+
+func (vr *viewportRenderer) emitHomeAfterScrollRegion() {
+	vr.homeAfterScrollRegion()
+	vr.emitCursorPosition(vr.row, vr.col)
+}
+
+func (vr *viewportRenderer) emitCursorPosition(row, col int) {
+	vr.pending.Write(vr.shifter.Shift([]byte(fmt.Sprintf("\x1b[%d;%dH", row, col))))
+}
+
 func (vr *viewportRenderer) lineFeed() {
 	if vr.row >= vr.scrollTop && vr.row == vr.scrollBottom {
 		vr.scrolled = true
@@ -426,7 +669,7 @@ func (vr *viewportRenderer) trackCSI(final byte, params []byte) {
 	case 'H', 'f':
 		r, c, ok := parseTwoParams(params)
 		if ok {
-			vr.row, vr.col = r, c
+			vr.row, vr.col = vr.originRow(r), c
 		}
 	case 'G', '`':
 		c, ok := parseOneParam(params, 1)
@@ -436,7 +679,7 @@ func (vr *viewportRenderer) trackCSI(final byte, params []byte) {
 	case 'd':
 		r, ok := parseOneParam(params, 1)
 		if ok {
-			vr.row = r
+			vr.row = vr.originRow(r)
 		}
 	case 'A':
 		n, ok := parseOneParam(params, 1)
@@ -459,19 +702,21 @@ func (vr *viewportRenderer) trackCSI(final byte, params []byte) {
 			vr.col -= n
 		}
 	case 'r':
-		vr.trackScrollRegion(params)
+		if vr.trackScrollRegion(params) {
+			vr.homeAfterScrollRegion()
+		}
 	}
 	vr.clampCursor()
 }
 
-func (vr *viewportRenderer) trackScrollRegion(params []byte) {
+func (vr *viewportRenderer) trackScrollRegion(params []byte) bool {
 	if len(params) == 0 {
 		vr.resetScrollRegion()
-		return
+		return true
 	}
 	top, bottom, ok := parseTwoParams(params)
 	if !ok {
-		return
+		return false
 	}
 	maxRows := int(vr.layout.childRows())
 	if maxRows < 1 {
@@ -484,10 +729,11 @@ func (vr *viewportRenderer) trackScrollRegion(params []byte) {
 		bottom = maxRows
 	}
 	if top >= bottom {
-		return
+		return false
 	}
 	vr.scrollTop = top
 	vr.scrollBottom = bottom
+	return true
 }
 
 func (vr *viewportRenderer) clampCursor() {

internal/app/viewport_renderer_test.go

@@ -29,6 +29,42 @@ func TestViewportRendererSwallowsAltScreenToggles(t *testing.T) {
 	}
 }
 
+func TestViewportRendererSwallowsOriginModeToggles(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	got := string(vr.Render([]byte("a\x1b[?6hb\x1b[?6lc")))
+	if strings.Contains(got, "\x1b[?6h") || strings.Contains(got, "\x1b[?6l") {
+		t.Fatalf("origin-mode toggles leaked to host: %q", got)
+	}
+	if !strings.Contains(got, "a") || !strings.Contains(got, "b") || !strings.Contains(got, "c") {
+		t.Fatalf("origin-mode toggles should not drop surrounding text: got %q", got)
+	}
+	if strings.Count(got, "\x1b[3;1H") != 2 {
+		t.Fatalf("origin-mode set/reset should home inside the viewport twice: got %q", got)
+	}
+}
+
+func TestViewportRendererSwallowsLeftRightMarginMode(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	got := string(vr.Render([]byte("a\x1b[?69h\x1b[10;80sb\x1b[?69lc")))
+	if strings.Contains(got, "\x1b[?69h") || strings.Contains(got, "\x1b[10;80s") || strings.Contains(got, "\x1b[?69l") {
+		t.Fatalf("left/right margin controls leaked to host: %q", got)
+	}
+	if got != "abc" {
+		t.Fatalf("left/right margin controls should be swallowed without dropping text: got %q", got)
+	}
+}
+
+func TestViewportRendererOriginModeCUPUsesScrollTop(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	got := string(vr.Render([]byte("\x1b[5;10r\x1b[?6h\x1b[1;1H")))
+	if strings.Contains(got, "\x1b[?6h") {
+		t.Fatalf("origin-mode set leaked to host: %q", got)
+	}
+	if !strings.Contains(got, "\x1b[7;1H") {
+		t.Fatalf("CUP row 1 in origin mode should land at scrollTop row 5 shifted to host row 7: got %q", got)
+	}
+}
+
 func TestViewportRendererClearScreenIsViewportOnly(t *testing.T) {
 	// hostRows=7 leaves four viewport rows after the 2-row tab bar and
 	// 1-row status reservation.
@@ -239,6 +275,73 @@ func TestViewportRendererFlagsLineFeedAtCustomScrollBottom(t *testing.T) {
 	}
 }
 
+// Long claude sessions can leave the child cursor at viewport row 1 and
+// then emit CSI A (cursor up) with a large step before redrawing. The
+// raw CSI A would walk the host cursor into the tab bar; the next
+// printable would then write into row 1 / row 2. Clamp the step at the
+// viewport top so the host cursor stays inside the viewport.
+func TestViewportRendererClampsCUUAtViewportTop(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	// CUP to viewport row 1 then CUU by 50.
+	got := string(vr.Render([]byte("\x1b[1;1H\x1b[50ACLOBBER")))
+	if !strings.Contains(got, "\x1b[3;1H") {
+		t.Fatalf("expected CUP shifted to mainTop: got %q", got)
+	}
+	// The CUU should have been swallowed (n clamped to 0 from row 1).
+	if strings.Contains(got, "\x1b[50A") {
+		t.Fatalf("CUU 50 from viewport row 1 leaked: got %q", got)
+	}
+	// And the subsequent printables should land inside the viewport,
+	// not above it.
+	if !strings.Contains(got, "CLOBBER") {
+		t.Fatalf("printables should still be emitted after clamped CUU: got %q", got)
+	}
+}
+
+func TestViewportRendererClampsCUUPartial(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	// CUP to viewport row 5, then CUU by 50 → safe step is 4.
+	got := string(vr.Render([]byte("\x1b[5;1H\x1b[50A")))
+	if !strings.Contains(got, "\x1b[4A") {
+		t.Fatalf("CUU 50 from row 5 should clamp to 4: got %q", got)
+	}
+	if strings.Contains(got, "\x1b[50A") {
+		t.Fatalf("unclamped CUU leaked: got %q", got)
+	}
+}
+
+func TestViewportRendererClampsCUDAtViewportBottom(t *testing.T) {
+	// childRows=37 for layout(120, 40). Park cursor at row 37, ask for
+	// 10 down → safe step is 0.
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	got := string(vr.Render([]byte("\x1b[37;1H\x1b[10B")))
+	if strings.Contains(got, "\x1b[10B") {
+		t.Fatalf("CUD past viewport bottom should be dropped: got %q", got)
+	}
+}
+
+func TestViewportRendererClampsCPLAndHomesColumn(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	// CUP to row 1 col 50 then CPL by 5 → step clamped to 0, but col
+	// must still reset to 1 (CR emitted).
+	got := string(vr.Render([]byte("\x1b[1;50H\x1b[5F")))
+	if strings.Contains(got, "\x1b[5F") {
+		t.Fatalf("CPL 5 from row 1 should not leak: got %q", got)
+	}
+	if !strings.Contains(got, "\r") {
+		t.Fatalf("CPL should home column to 1 with CR: got %q", got)
+	}
+}
+
+func TestViewportRendererClampsCNL(t *testing.T) {
+	vr := newViewportRenderer(newTerminalLayout(120, 40))
+	// CUP to row 35 then CNL by 50 → safe step is 2 (childRows-35).
+	got := string(vr.Render([]byte("\x1b[35;10H\x1b[50E")))
+	if !strings.Contains(got, "\x1b[2E") {
+		t.Fatalf("CNL 50 from row 35 should clamp to 2: got %q", got)
+	}
+}
+
 func TestViewportRendererForwardsRIVerbatim(t *testing.T) {
 	// We rely on the host terminal performing the scroll inside the
 	// DECSTBM region; the renderer must not eat or transform RI. If a