Parse DEC allow column switch mode

Author: SqlRush

docs/cc-100-roadmap.md

@@ -156,6 +156,8 @@ M7 补充：terminal CSI parser 现在把 DEC `?1h/l` application cursor mode 
 
 M7 补充：terminal CSI parser 现在把 DEC `?3h/l` 132/80-column mode 解析成结构化 `columnMode` action，覆盖常见列宽状态切换序列。
 
+M7 补充：terminal CSI parser 现在把 DEC `?40h/l` allow column switching mode 解析成结构化 `allowColumnSwitch` mode action，补齐 `?3h/l` 列宽切换相邻的许可状态序列。
+
 M7 补充：terminal CSI parser 现在把 DEC `?5h/l` reverse video/screen mode 解析成结构化 `reverseVideo` mode action，继续减少终端显示状态序列的 unknown fallback。
 
 M7 补充：terminal CSI parser 现在把普通 `CSI 4h/l` insert/replace mode 解析成 `insertMode` action，避免 ECMA mode set/reset 序列落入 unknown。

docs/claude-code-go-rewrite-plan.md

@@ -261,6 +261,7 @@ test/parity/                 # golden tests against TS/official behavior
 - 本轮补充：terminal sequence dispatcher 把 SS3 application cursor (`ESC OA`/`OB`/`OC`/`OD`) 归入结构化 cursor move action，避免 application cursor mode 序列落入 unknown。
 - 本轮补充：terminal CSI parser 把 DEC `?1h/l` application cursor mode 解析成独立 mode action，和 SS3 application cursor key 解析闭环。
 - 本轮补充：terminal CSI parser 把 DEC `?3h/l` 132/80-column mode 解析成结构化 `columnMode` action，覆盖常见列宽状态切换序列。
+- 本轮补充：terminal CSI parser 把 DEC `?40h/l` allow column switching mode 解析成结构化 `allowColumnSwitch` mode action，补齐 `?3h/l` 列宽切换相邻的许可状态序列。
 - 本轮补充：terminal CSI parser 把 DEC `?5h/l` reverse video/screen mode 解析成结构化 `reverseVideo` mode action，继续减少终端显示状态序列的 unknown fallback。
 - 本轮补充：terminal CSI parser 把普通 `CSI 4h/l` insert/replace mode 解析成 `insertMode` action，避免 ECMA mode set/reset 序列落入 unknown。
 - 本轮补充：terminal CSI parser 把普通 `CSI 20h/l` line-feed/new-line mode 解析成 `lineFeedMode` action，继续覆盖 ECMA mode set/reset 序列。

docs/first-second-parity-audit.md

@@ -212,6 +212,7 @@ M7 progress now includes:
 - `internal/tui`: terminal CSI parser now recognizes xterm alternate scroll mode (`?1007h/l`) as a structured mode action instead of an unknown sequence.
 - `internal/tui`: terminal CSI parser now recognizes DEC application cursor mode (`?1h/l`) as a structured mode action, pairing with SS3 application cursor key parsing.
 - `internal/tui`: terminal CSI parser now recognizes DEC 132/80-column mode (`?3h/l`) as a structured `columnMode` action.
+- `internal/tui`: terminal CSI parser now recognizes DEC allow-column-switching mode (`?40h/l`) as a structured `allowColumnSwitch` mode action.
 - `internal/tui`: terminal CSI parser now recognizes DEC reverse video/screen mode (`?5h/l`) as a structured `reverseVideo` mode action.
 - `internal/tui`: terminal CSI parser now recognizes ordinary ECMA insert/replace mode (`CSI 4h/l`) as a structured `insertMode` action.
 - `internal/tui`: terminal CSI parser now recognizes ordinary ECMA line-feed/new-line mode (`CSI 20h/l`) as a structured `lineFeedMode` action.

internal/tui/terminal_csi.go

@@ -75,8 +75,9 @@ const (
 	DECModeMouseX10           = 9
 	DECModeCursorBlink        = 12
 	DECModeCursorVisible      = 25
-	DECModeAltScreen          = 47
+	DECModeAllowColumnSwitch  = 40
 	DECModeReverseWrap        = 45
+	DECModeAltScreen          = 47
 	DECModeApplicationKeypad  = 66
 	DECModeBackarrowKey       = 67
 	DECModeAltScreenBuffer    = 1047
@@ -235,6 +236,7 @@ const (
 	CSIModeActionInsert            CSIModeActionType = "insertMode"
 	CSIModeActionLineFeed          CSIModeActionType = "lineFeedMode"
 	CSIModeActionColumn            CSIModeActionType = "columnMode"
+	CSIModeActionAllowColumnSwitch CSIModeActionType = "allowColumnSwitch"
 	CSIModeActionReverseVideo      CSIModeActionType = "reverseVideo"
 	CSIModeActionOrigin            CSIModeActionType = "originMode"
 	CSIModeActionAutoWrap          CSIModeActionType = "autoWrap"
@@ -579,6 +581,8 @@ func csiPrivateModeAction(mode int, enabled bool) (CSIAction, bool) {
 		return CSIAction{Type: CSIActionMode, Mode: CSIModeAction{Type: CSIModeActionApplicationCursor, Enabled: enabled}}, true
 	case DECModeColumn:
 		return CSIAction{Type: CSIActionMode, Mode: CSIModeAction{Type: CSIModeActionColumn, Enabled: enabled}}, true
+	case DECModeAllowColumnSwitch:
+		return CSIAction{Type: CSIActionMode, Mode: CSIModeAction{Type: CSIModeActionAllowColumnSwitch, Enabled: enabled}}, true
 	case DECModeReverseVideo:
 		return CSIAction{Type: CSIActionMode, Mode: CSIModeAction{Type: CSIModeActionReverseVideo, Enabled: enabled}}, true
 	case DECModeOrigin:

internal/tui/tui_test.go

@@ -3650,6 +3650,8 @@ func TestParseCSISequenceActions(t *testing.T) {
 		{seq: "\x1b[?1l", want: CSIModeAction{Type: CSIModeActionApplicationCursor, Enabled: false}},
 		{seq: "\x1b[?3h", want: CSIModeAction{Type: CSIModeActionColumn, Enabled: true}},
 		{seq: "\x1b[?3l", want: CSIModeAction{Type: CSIModeActionColumn, Enabled: false}},
+		{seq: "\x1b[?40h", want: CSIModeAction{Type: CSIModeActionAllowColumnSwitch, Enabled: true}},
+		{seq: "\x1b[?40l", want: CSIModeAction{Type: CSIModeActionAllowColumnSwitch, Enabled: false}},
 		{seq: "\x1b[?5h", want: CSIModeAction{Type: CSIModeActionReverseVideo, Enabled: true}},
 		{seq: "\x1b[?5l", want: CSIModeAction{Type: CSIModeActionReverseVideo, Enabled: false}},
 		{seq: "\x1b[?6h", want: CSIModeAction{Type: CSIModeActionOrigin, Enabled: true}},