fix(mobile): send a shell Paste image to the session the dialog was opened for

The Paste dialog's image branch called _uploadAndInsertImages() without a
session, so it fell back to the active session at pick time: after a tab
switch with the dialog open, the image went to the other tab, while the
text Send already used the session captured at open.

Also corrects the comments around the shared bracketed write: the size
refusal now lives in _sendBracketedPaste(), the budget covers the shell
Paste too, and a shell without bracketed paste (dash, bash before 5.1)
gets the markers stripped by tmux, so every line but the last still runs
there.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/public/keyboard-accessory.js

@@ -636,12 +636,13 @@ function applyOneShotCtrl(data) {
   return { data, consumed: true };
 }
 
-// The composer's Send goes out as ONE bracketed-paste frame on the WebSocket
-// input path, and ws-routes.ts drops a frame longer than MAX_INPUT_LENGTH
-// (config/terminal-limits.ts: 64 KiB, compared in UTF-16 code units) WITHOUT
-// an ACK, which would wedge the durable input queue. So the prompt budget is
-// that limit minus the two markers, derived here once so the refusal in
-// _sendComposedPrompt() and the toast that names the maximum cannot drift.
+// The composer's Send, and the shell Paste dialog's, goes out as ONE
+// bracketed-paste frame on the WebSocket input path, and ws-routes.ts drops a
+// frame longer than MAX_INPUT_LENGTH (config/terminal-limits.ts: 64 KiB,
+// compared in UTF-16 code units) WITHOUT an ACK, which would wedge the durable
+// input queue. So the budget is that limit minus the two markers, derived here
+// once so the refusal in _sendBracketedPaste() and the toast that names the
+// maximum cannot drift.
 const COMPOSER_INPUT_FRAME_LIMIT = 64 * 1024;
 const COMPOSER_PASTE_START = '\x1b[200~';
 const COMPOSER_PASTE_END = '\x1b[201~';
@@ -664,7 +665,7 @@ const KeyboardAccessoryBar = {
   _composerDrafts: new Map(),
   _composerUploads: new Map(),
   _composerOverlay: null,
-  // Longest prompt Send accepts: the input frame limit minus both markers.
+  // Longest prompt or shell paste Send accepts: the input frame limit minus both markers.
   _composerMaxLength: COMPOSER_INPUT_FRAME_LIMIT - COMPOSER_PASTE_START.length - COMPOSER_PASTE_END.length,
 
   /** HTML for simple mode: arrows, commands, Compose, Esc, dismiss */
@@ -1205,11 +1206,12 @@ const KeyboardAccessoryBar = {
     textarea.dispatchEvent(new Event('input', { bubbles: true }));
   },
 
-  /** Deliver one complete prompt as an explicit bracketed paste. xterm loses
-   *  its DECSET 2004 mirror after terminal replay, even though the CLI still
-   *  expects bracketed input, so build the byte-identical sequence directly on
-   *  the durable session-bound path. Enter stays a separate delayed write
-   *  because Codex drops keys sharing a PTY read with a bracketed paste. */
+  /** Deliver one complete prompt as an explicit bracketed paste
+   *  (_sendBracketedPaste()), then Enter. xterm loses its DECSET 2004 mirror
+   *  after terminal replay, even though the CLI still expects bracketed input,
+   *  so the frame is built directly rather than through terminal.paste().
+   *  Enter stays a separate delayed write because Codex drops keys sharing a
+   *  PTY read with a bracketed paste. */
   _sendComposedPrompt(sessionId, text) {
     if (!this._sendBracketedPaste(sessionId, text, 'Prompt')) return false;
     setTimeout(() => app._sendInputAsync(sessionId, '\r', { useMux: true }), 120);
@@ -1444,7 +1446,9 @@ const KeyboardAccessoryBar = {
     // Only shell sessions reach this overlay (agent bars get Compose instead),
     // so the text lands at the prompt as one bracketed paste and is NOT run:
     // sent raw, every newline was an Enter and each line ran on its own as it
-    // arrived. The user reviews the block and presses Enter themselves.
+    // arrived. The user reviews the block and presses Enter themselves. A shell
+    // that never enabled bracketed paste (dash, bash before 5.1) gets the
+    // markers stripped by tmux, so there every line but the last still runs.
     const sendText = () => {
       const text = textarea.value;
       if (!text) {
@@ -1461,7 +1465,8 @@ const KeyboardAccessoryBar = {
       const images = Array.from(files || []).filter((f) => f.type.startsWith('image/'));
       if (images.length === 0) return false;
       close();
-      if (typeof app._uploadAndInsertImages === 'function') app._uploadAndInsertImages(images);
+      // Upload to, and insert into, the shell this overlay was opened for.
+      if (typeof app._uploadAndInsertImages === 'function') app._uploadAndInsertImages(images, { sessionId });
       return true;
     };