feat(tui/paste): show [image: filename] placeholder and map to temp path

- Composer now inserts a placeholder instead of a full temp path when an image
  is pasted (from clipboard or base64/data-URI).
- Added AppEvent::RegisterPastedImage; composer notifies ChatWidget to map the
  placeholder to its backing file so submit resolves to LocalImage.
- Keeps visual consistency with drag-and-drop and avoids leaking temp paths in
  the visible message.

codex-rs/tui/src/app.rs

@@ -546,6 +546,11 @@ impl App<'_> {
                 AppEvent::Paste(text) => {
                     self.dispatch_paste_event(text);
                 }
+                AppEvent::RegisterPastedImage { placeholder, path } => {
+                    if let AppState::Chat { widget } = &mut self.app_state {
+                        widget.register_pasted_image(placeholder, path);
+                    }
+                }
                 AppEvent::CodexEvent(event) => {
                     self.dispatch_codex_event(event);
                 }

codex-rs/tui/src/app_event.rs

@@ -14,6 +14,7 @@ use crate::bottom_pane::chrome_selection_view::ChromeLaunchOption;
 use crate::slash_command::SlashCommand;
 use codex_protocol::models::ResponseItem;
 use std::fmt;
+use std::path::PathBuf;
 
 /// Wrapper to allow including non-Debug types in Debug enums without leaking internals.
 pub(crate) struct Redacted<T>(pub T);
@@ -127,5 +128,9 @@ pub(crate) enum AppEvent {
         prefix_items: Vec<ResponseItem>,
         prefill: String,
     },
+
+    /// Register an image placeholder inserted by the composer with its backing path
+    /// so ChatWidget can resolve it to a LocalImage on submit.
+    RegisterPastedImage { placeholder: String, path: PathBuf },
     
 }

codex-rs/tui/src/bottom_pane/chat_composer.rs

@@ -30,6 +30,7 @@ use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
 use crate::bottom_pane::textarea::TextArea;
 use crate::bottom_pane::textarea::TextAreaState;
+use crate::app_event::AppEvent;
 use crate::clipboard_paste::normalize_pasted_path;
 use crate::clipboard_paste::paste_image_to_temp_png;
 use crate::clipboard_paste::try_decode_base64_image_to_temp_png;
@@ -415,9 +416,16 @@ impl ChatComposer {
         let char_count = pasted.chars().count();
         // If the pasted text looks like a base64/data-URI image, decode it and insert as a path.
         if let Ok((path, info)) = try_decode_base64_image_to_temp_png(&pasted) {
-            let path_str = path.to_string_lossy();
-            self.textarea.insert_str(&path_str);
+            let filename = path
+                .file_name()
+                .and_then(|n| n.to_str())
+                .unwrap_or("image.png");
+            let placeholder = format!("[image: {}]", filename);
+            // Insert placeholder and notify chat widget about the mapping.
+            self.textarea.insert_str(&placeholder);
             self.textarea.insert_str(" ");
+            self.app_event_tx
+                .send(AppEvent::RegisterPastedImage { placeholder: placeholder.clone(), path });
             self.flash_footer_notice(format!("Added image {}x{} (PNG)", info.width, info.height));
         } else if char_count > LARGE_PASTE_CHAR_THRESHOLD {
             let placeholder = format!("[Pasted Content {char_count} chars]");
@@ -429,9 +437,15 @@ impl ChatComposer {
             // No textual content pasted — try reading an image directly from the OS clipboard.
             match paste_image_to_temp_png() {
                 Ok((path, info)) => {
-                    let path_str = path.to_string_lossy();
-                    self.textarea.insert_str(&path_str);
+                    let filename = path
+                        .file_name()
+                        .and_then(|n| n.to_str())
+                        .unwrap_or("image.png");
+                    let placeholder = format!("[image: {}]", filename);
+                    self.textarea.insert_str(&placeholder);
                     self.textarea.insert_str(" ");
+                    self.app_event_tx
+                        .send(AppEvent::RegisterPastedImage { placeholder: placeholder.clone(), path });
                     // Give a small visual confirmation in the footer.
                     self.flash_footer_notice(format!(
                         "Added image {}x{} (PNG)",

codex-rs/tui/src/chatwidget.rs

@@ -1322,6 +1322,11 @@ impl ChatWidget<'_> {
         self.bottom_pane.insert_str(s);
     }
 
+    pub(crate) fn register_pasted_image(&mut self, placeholder: String, path: std::path::PathBuf) {
+        self.pending_images.insert(placeholder, path);
+        self.request_redraw();
+    }
+
     fn parse_message_with_images(&mut self, text: String) -> UserMessage {
         use std::path::Path;
 

codex-rs/tui/src/clipboard_paste.rs

@@ -127,7 +127,10 @@ pub fn try_decode_base64_image_to_temp_png(pasted: &str) -> Result<(PathBuf, Pas
 
     // Remove whitespace that might be wrapped by terminals
     let compact: String = b64.chars().filter(|c| !c.is_whitespace()).collect();
-    let bytes = base64::decode(compact).map_err(|e| PasteImageError::DecodeFailed(e.to_string()))?;
+    use base64::Engine as _;
+    let bytes = base64::engine::general_purpose::STANDARD
+        .decode(compact)
+        .map_err(|e| PasteImageError::DecodeFailed(e.to_string()))?;
 
     // Load via `image` crate to get dimensions and normalize to PNG
     let dyn_img = image::load_from_memory(&bytes)