feat(ui): add dynamic input window toggle

[aweis89]

Summary

• Add ability to toggle (hide/show) the input window independently of the output window
• Add new ui.input.dynamic config option that automatically hides the input window when focus moves to the output window or when a prompt is submitted

Motivation

When working with AI responses, the output window benefits from maximum screen real estate. The input window (especially when configured larger) takes up space that isn't needed while waiting for or reading responses. This feature allows the input window to stay out of the way until you're ready to type the next prompt.

Features

Toggle Input Window

• New toggle_input API function and command (:Opencode toggle_input)
• Default keymap: <M-i> (Alt+i) in both input and output windows
• When hidden, the input window is completely closed (not just minimized) to give full space to the output
• Input buffer content is preserved when hidden

Dynamic Input Mode (ui.input.auto_hide = true)

• When enabled, the input window automatically hides when:
  • Submitting a prompt (<cr>)
  • Focus moves to the output window (via any method - keymaps, mouse, <C-w> commands, etc.)
• The input window automatically shows when focusing it via focus_input, open_input, or toggle_pane
• When toggling the UI with dynamic mode enabled, no longer defaults to last focused window (always focuses input)

Bug Fixes

Auto-scroll preservation during dynamic input resize

When the input window hides/shows with dynamic = true, the output window resizes. This could incorrectly update viewport_at_bottom via the WinScrolled autocmd, breaking auto-scroll. Fixed by:

• Capturing was_at_bottom state before hide/show
• Scheduling scroll_to_bottom() after resize if previously at bottom

Tab keymap conflicts with completion plugins

• Fix: Restricted the default <Tab> toggle focus mapping to only trigger in normal mode, preventing conflicts with auto-complete mappings that use <Tab> in insert mode

Test Fixes

Date formatting tests fail on year boundaries (CI)

Tests for util.format_time failed when run on year boundaries (e.g., Jan 1, 2026):

• "formats yesterday" expected 31 Dec 09:46 PM but got 31 Dec 2025 09:46 PM (year included because Dec 31 is a different year than Jan 1)
• "formats last week" had the same issue
• "handles large millisecond timestamps" also failed due to year comparison

Fix: Made tests year-boundary-aware by checking if test dates fall in the same year as today before asserting the expected format pattern.

Files Changed

• lua/opencode/api.lua - Add toggle_input, update submit_input_prompt, toggle
• lua/opencode/config.lua - Add ui.input.dynamic option and keymaps
• lua/opencode/ui/autocmds.lua - Prevent closing all windows during toggle
• lua/opencode/ui/input_window.lua - Add toggle, _hide, _show, is_hidden functions; preserve scroll position
• lua/opencode/ui/output_window.lua - Auto-hide input on focus when dynamic enabled
• lua/opencode/ui/ui.lua - Handle hidden state in focus_input, simplify toggle_pane
• tests/unit/util_spec.lua - Fix year-boundary-aware date formatting tests

[aweis89]

@sudo-tee curious to hear if you had any thoughts on this if you had a chance to try it out.

• Perhaps dynamic = true should not be the default?
• It is more inline with the way the TUI works, where the input window is hiddent during model output I believe
• The main advantage for me is having a larger input window without having to compromise on output window size
• Hitting i from the output window, to get the input window (in insert mode) has been perferable to a static input window in my experience but curious if you have reservations

[sudo-tee]

I didn't had time to look at it yet. Been busy with the holidays and family. But I will look at it pretty soon

[sudo-tee]

I like the idea.

However the implementation feels a bit rough. There is a good amount of layout shifting when toggling the input.

When I move the cursor to the code window the input should also auto_hide, as it feels weird that it hide when focusing back to the opencode window. I attached a video

Screen.Recording.2026-01-05.074018.mp4

I think a better solution would be to make the input a floating window when in auto_hide mode, it would reduce the layout shifting.

What do you think ?

[aaronweisberg]

I like the idea.

However the implementation feels a bit rough. There is a good amount of layout shifting when toggling the input.

When I move the cursor to the code window the input should also auto_hide, as it feels weird that it hide when focusing back to the opencode window. I attached a video
Screen.Recording.2026-01-05.074018.mp4

I mostly used this in full-screen mode position = "current" so I didn't consider the intended behavior when switching to another split. I think the input window should be hidden whenever the focus shifts away from the input window instead. I think this will feel less weird. Curious to hear what you think if you're able to try again though.

I think a better solution would be to make the input a floating window when in auto_hide mode, it would reduce the layout shifting.

What do you think ?

I think a floating window would add some additional complexities. Ideally when the input window is being hidden, we want to the output window to maximize it's size (so static padding wouldn't be ideal), we also don't want to hide the latest text of the output window behind the input window when the input window is open. Perhaps this can be explored in a future dedicated PR if there's a way to make this better through a float though I'm a bit skeptical.

[sudo-tee]

I think a floating window would add some additional complexities. Ideally when the input window is being hidden, we want to the output window to maximize it's size (so static padding wouldn't be ideal), we also don't want to hide the latest text of the output window behind the input window when the input window is open. Perhaps this can be explored in a future dedicated PR if there's a way to make this better through a float though I'm a bit skeptical.

This is reasonable as long as it's not the default

[sudo-tee]

Looks fine now as it is not the default behavior.

The only thing needed is to remove unnecessary comments. Most of the time it's pretty obvious on what the code does. I commented on a couple of ones as example.

[aweis89]

Fixed some auto-scrolling so the dynamic input window doesn't block the latest text.
I think this should be good to go 🎉

[sudo-tee]

Thanks for the fixes.

It should be good to go