Merge #555: opencode drags select text and the wheel pages its transcript

src/session.ts

@@ -277,10 +277,11 @@ function cliExportsTruecolor(mode: SessionMode): boolean {
  * Codex, Claude Code, and Gemini are known, controlled (Ink/React) TUIs that
  * repaint via cursor positioning, so dropping the alt-screen switch is safe —
  * content stays in the normal buffer. Excluded: `shell` (arbitrary programs like
- * vim/less/htop legitimately need the alt screen), `opencode` (renders its own
- * TUI that may rely on it), `pi` (below) and `grok` (a fullscreen alt-screen TUI
- * with mouse support, i.e. the opencode case, not the Ink case). Keep parity
- * with the replay-side strip in session-routes.ts.
+ * vim/less/htop legitimately need the alt screen), `opencode` (its own MIDDLE strip,
+ * isMuxMouseStripMode), `pi` (below) and `grok` (a fullscreen alt-screen TUI with
+ * mouse support). Keep parity with the replay-side strip (`stripReplayBuffer` in
+ * session-routes.ts); the table in `CliCapabilities.altScreen` is pinned for every
+ * stock CLI in test/claude-scrollback-strip.test.ts.
  *
  * ⚠️ Being excluded here does NOT preserve the alt screen. Every excluded mode
  * falls through to isMuxAltScreenOnlyStripMode(), which strips the alt-screen
@@ -300,8 +301,10 @@ export function isAltScreenStripMode(mode: SessionMode): boolean {
 
 /**
  * Modes that need the NARROW strip: alt-screen toggles only, leaving `\x1b[3J`
- * and the mouse-tracking DECSETs alone. Applies to every mode `isAltScreenStripMode`
- * excludes, but ONLY when the session is tmux-backed (`useMux`).
+ * and the mouse-tracking DECSETs alone. Applies to every mode that is neither
+ * `strip-full` (isAltScreenStripMode) nor `strip-mux-and-mouse` (isMuxMouseStripMode),
+ * so `strip-mux-only` and `preserve` alike, but ONLY when the session is tmux-backed
+ * (`useMux`).
  *
  * The bug (issue #205): the tmux CLIENT emits `smcup` (`\x1b[?1049h`) as its first
  * bytes on attach, before any program has run. Unstripped, xterm.js parks in the
@@ -326,7 +329,31 @@ export function isAltScreenStripMode(mode: SessionMode): boolean {
  * `\x1b[3J` from a user's own `clear` is a deliberate "wipe my scrollback".
  */
 export function isMuxAltScreenOnlyStripMode(mode: SessionMode, useMux: boolean): boolean {
-  return useMux && !isAltScreenStripMode(mode);
+  if (!useMux) return false;
+  const altScreen = getCli(mode)?.capabilities.altScreen;
+  return altScreen !== 'strip-full' && altScreen !== 'strip-mux-and-mouse';
+}
+
+/**
+ * Modes whose mouse-tracking DECSETs must be stripped, leaving `3J` alone:
+ * `altScreen: 'strip-mux-and-mouse'`, i.e. a mouse-capable full-screen TUI.
+ *
+ * Why this exists (opencode, measured 2026-09-16): the TUI enables tracking
+ * DECSETs, tmux runs with `mouse off` and therefore passes the PANE's DECSETs
+ * straight through to the tmux client, and the browser's xterm obeyed them —
+ * `mouseTrackingMode` flipped to `'any'` and xterm then reported DRAGS to the TUI
+ * instead of selecting locally. "Mark text, copy on select" silently did nothing
+ * (measured 62 `none` / 18 `any` over 16s, and 5/5 dead drags while `any`), and
+ * the obvious fallback — Ctrl+C — is opencode's `app_exit`, so the failure also
+ * ended sessions. Stripping at the source keeps xterm in selection mode; clicks
+ * still reach the CLI through the browser's hand-encoded tap, which this strip
+ * publishes as `cliMouseTracking` (`_recordStrippedMouseMode`).
+ *
+ * Gated on `useMux` for the same reason as the narrow strip: on the direct-PTY
+ * fallback the program's own DECSETs really do reach xterm and must be honoured.
+ */
+export function isMuxMouseStripMode(mode: SessionMode, useMux: boolean): boolean {
+  return useMux && getCli(mode)?.capabilities.altScreen === 'strip-mux-and-mouse';
 }
 
 // Note: Claude CLI PATH resolution moved to session-cli-builder.ts (buildClaudeEnv)
@@ -2529,14 +2556,21 @@ export class Session extends EventEmitter {
     // redraws overwrite only the cells they target, so non-erased rows keep
     // their content. Gated to Codex/Claude/Gemini (isAltScreenStripMode).
     //
-    // Every OTHER mode (shell/opencode/antigravity) gets the NARROW strip when it
-    // is tmux-backed: alt-screen toggles only, because the sequence that breaks
+    // Every OTHER mode (shell/antigravity/pi/grok/deepseek/omp) gets the NARROW strip
+    // when it is tmux-backed: alt-screen toggles only, because the sequence that breaks
     // scrollback there is tmux's own client-side smcup at attach, not anything the
     // program in the pane emitted (issue #205, see isMuxAltScreenOnlyStripMode).
     // 3J and the mouse DECSETs stay, so `clear` and mouse-aware TUIs keep working.
+    //
+    // The MIDDLE case (isMuxMouseStripMode) is a mouse-capable full-screen TUI:
+    // it needs smcup AND the mouse DECSETs gone — otherwise the pane's tracking
+    // reaches xterm and every drag becomes a mouse report instead of a text
+    // selection, which is what killed mark-and-copy in opencode — while 3J stays,
+    // because a TUI is not a `clear` consumer.
     const fullStrip = isAltScreenStripMode(this.mode);
-    const altOnlyStrip = !fullStrip && isMuxAltScreenOnlyStripMode(this.mode, this._useMux);
-    if (fullStrip || altOnlyStrip) {
+    const mouseStrip = isMuxMouseStripMode(this.mode, this._useMux);
+    const altOnlyStrip = !fullStrip && !mouseStrip && isMuxAltScreenOnlyStripMode(this.mode, this._useMux);
+    if (fullStrip || mouseStrip || altOnlyStrip) {
       // Reassemble sequences split across PTY chunk boundaries first: a chunk
       // ending mid-sequence ('\x1b[?104' now, '9h' next) would slip past the
       // strip below and leave xterm stuck in the scrollback-less alt buffer
@@ -2555,14 +2589,18 @@ export class Session extends EventEmitter {
       // eslint-disable-next-line no-control-regex
       data = data.replace(/\x1b\[\?(?:47|1047|1049)[hl]/g, '');
       if (fullStrip) {
-        data = data
+        // eslint-disable-next-line no-control-regex
+        data = data.replace(/\x1b\[3J/g, '');
+      }
+      if (fullStrip || mouseStrip) {
+        data = data.replace(
           // eslint-disable-next-line no-control-regex
-          .replace(/\x1b\[3J/g, '')
-          // eslint-disable-next-line no-control-regex
-          .replace(/\x1b\[\?(?:1000|1001|1002|1003|1005|1006|1007)[hl]/g, (seq) => {
+          /\x1b\[\?(?:1000|1001|1002|1003|1005|1006|1007)[hl]/g,
+          (seq) => {
             this._recordStrippedMouseMode(seq);
             return '';
-          });
+          }
+        );
       }
     }