- Pasting non-image files (.docx/.pdf/.py …) was folded as `[Image #N]`
because clipboard helper returned any file path. Split into image vs
file by extension; non-images now fold as `[File #N]` and expand to
the path on submit, same flow as images.
- Backspace/Delete used to nibble placeholders one char at a time.
Override `action_delete_left/right`: when the caret sits flush against
a `[Pasted text #N +X lines]` / `[Image #N]` / `[File #N]` placeholder
on the matching side, remove the whole span and drop its dict entry.
- Ctrl+C inside the input was clearing the whole field. Root cause:
`screen.get_selected_text()` doesn't see TextArea's internal selection,
so the handler fell through to the input-reset branch. Fixed by
preferring the focused InputArea's `selected_text` before screen-level
drag selection.
- Input text/history/pastes were globally shared across agent sessions
(single InputArea widget). Moved the four state slots
(text/history/pastes/paste_counter) onto `AgentSession`, with a
`_swap_input_for_session` snapshot/restore on session switch.
nianyucatfish
dfac66d972
