perf: open the panel without waiting on session #134

sudo-tee · 2025-12-05T02:39:41Z

This PR is removing the :wait on the critical paths in favor of a coroutine similar to how promises work in js.

This should resolve #137 and #133

sudo-tee · 2025-12-05T02:46:55Z

There is still some issues, like test and context not loading properly, but it's a start

Copilot

Pull request overview

This PR improves performance by making the panel opening process asynchronous. Instead of blocking while initializing the session and server, the UI is created immediately and displays "Loading..." while initialization happens in the background via vim.schedule(). This is achieved by introducing an is_opening state flag and returning promises from the core.open() function to allow proper async flow control.

Key changes:

Refactored core.open() to be asynchronous using vim.schedule() and promises
Added is_opening state flag to track initialization status and display "Loading..." in the UI
Updated API functions to chain promises with :and_then() for proper async orchestration

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
lua/opencode/state.lua	Adds `is_opening` boolean field to track panel opening state
lua/opencode/ui/topbar.lua	Displays "Loading..." when `is_opening` is true and subscribes to state changes
lua/opencode/core.lua	Refactors `M.open()` to be async with promises, moves session initialization into `vim.schedule()`, and adds error logging
lua/opencode/api.lua	Updates API functions to return promises, chains `core.open()` with `:and_then()`, removes redundant `local config` declarations, and changes default focus from 'output' to 'input' in `M.run()` functions

Comments suppressed due to low confidence (1)

lua/opencode/core.lua:186

The send_message function doesn't return the promise from api_client:create_message(). This breaks the promise chain in API functions like M.run() and M.run_new_session() which expect to chain this with :and_then().

Add return before the state.api_client:create_message() call to properly propagate the promise:

return state.api_client
  :create_message(session_id, params)
  :and_then(function(response)
    -- ...
  end)
  :catch(function(err)
    -- ...
  end)

  state.api_client
    :create_message(session_id, params)
    :and_then(function(response)
      if not response or not response.info or not response.parts then
        -- fall back to full render. incremental render is handled
        -- event manager
        vim.notify('Invalid response from session: ' .. vim.inspect(response), vim.log.levels.ERROR)
        ui.render_output()
        return
      end

      local received_message_count = vim.deepcopy(state.user_message_count)
      received_message_count[response.info.sessionID] = (received_message_count[response.info.sessionID] ~= nil)
          and (received_message_count[response.info.sessionID] - 1)
        or 0
      state.user_message_count = received_message_count

      M.after_run(prompt)
    end)
    :catch(function(err)
      vim.notify('Error sending message to session: ' .. vim.inspect(err), vim.log.levels.ERROR)
      M.cancel()
    end)

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lua/opencode/api.lua

lua/opencode/core.lua

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cameronr · 2025-12-05T04:51:05Z

Hmm, the UI panels open faster but then I still get a noticeable blocking pause after the panels appear:

I think the underlying issues is the Promise:wait in ensure_server:

opencode.nvim/lua/opencode/server_job.lua

Lines 134 to 155 in 9223b98

    
           function M.ensure_server() 
        
             if state.opencode_server and state.opencode_server:is_running() then 
        
               return state.opencode_server 
        
             end 
        
             local promise = Promise.new() 
        
             state.opencode_server = opencode_server.new() 
        
             state.opencode_server:spawn({ 
        
               on_ready = function(_, base_url) 
        
                 promise:resolve(state.opencode_server) 
        
               end, 
        
               on_error = function(err) 
        
                 promise:reject(err) 
        
               end, 
        
               on_exit = function(exit_opts) 
        
                 promise:reject('Server exited') 
        
               end, 
        
             }) 
        
             return promise:wait() 
        
           end

Instead of doing :wait there, maybe we can just return the promise? Also, since ensure_server sets state.opencode_server, we don't need to return it from that function.

sudo-tee · 2025-12-05T12:42:08Z

Hmm, the UI panels open faster but then I still get a noticeable blocking pause after the panels appear:

Instead of doing :wait there, maybe we can just return the promise? Also, since ensure_server sets state.opencode_server, we don't need to return it from that function.

I will see what I can do. But even then until the server is loaded you cannot display most of the UI elements.

sudo-tee · 2025-12-05T14:18:21Z

@cameronr

I pushed a couple of improvements and removed the :wait()

It improved a little bit, there is no jumping of the cursor, but we still have to wait for the session to be loaded. Which in itself is un-avoidable.

Screen.Recording.2025-12-05.091554.mp4

cameronr · 2025-12-05T18:34:00Z

It's improving but I still get a UI freeze. I think the core problem is that Promse:wait uses vim.wait which blocks the neovim UI. I think it's fine if we're not able to fill in our UI elements until the opencode server starts but we shouldn't be blocking the neovim UI while we're waiting for that and I think that blocking is what makes it "feel" slow.

I added a debug.traceback() print to Promise:wait and it's called from these places when opening the panels:

              waiting
stack traceback:
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:173: in function <...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:162>
	[C]: in function 'pcall'
	...ev/neovim-dev/opencode.nvim/lua/opencode/config_file.lua:13: in function 'get_opencode_config'
	...ev/neovim-dev/opencode.nvim/lua/opencode/config_file.lua:76: in function 'get_opencode_agents'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:373: in function 'ensure_current_mode'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:84: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81>
	[C]: in function 'pcall'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:80>
	[C]: in function 'pcall'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:81: in function 'cb'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:43: in function ''
	vim/_editor.lua: in function <vim/_editor.lua:0>
              waiting
stack traceback:
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:173: in function <...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:162>
	[C]: in function 'pcall'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:45: in function 'get_all_sessions'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:83: in function 'get_all_workspace_sessions'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:109: in function 'get_last_workspace_session'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:97: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81>
	[C]: in function 'pcall'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:80>
	[C]: in function 'pcall'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:81: in function 'cb'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:43: in function ''
	vim/_editor.lua: in function <vim/_editor.lua:0>
              waiting
stack traceback:
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:173: in function <...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:162>
	[C]: in function 'pcall'
	...ev/neovim-dev/opencode.nvim/lua/opencode/config_file.lua:31: in function 'get_opencode_project'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:9: in function 'project_id'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:27: in function 'get_workspace_session_path'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:61: in function <...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:60>
	vim/shared.lua: in function 'get_all_sessions'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:83: in function 'get_all_workspace_sessions'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/session.lua:109: in function 'get_last_workspace_session'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:97: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81>
	[C]: in function 'pcall'
	...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:81: in function <...s/cam/Dev/neovim-dev/opencode.nvim/lua/opencode/core.lua:80>
	[C]: in function 'pcall'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:81: in function 'cb'
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:43: in function ''
	vim/_editor.lua: in function <vim/_editor.lua:0>
              waiting
stack traceback:
	...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:173: in function <...am/Dev/neovim-dev/opencode.nvim/lua/opencode/promise.lua:162>
	[C]: in function 'pcall'
	...ev/neovim-dev/opencode.nvim/lua/opencode/config_file.lua:48: in function 'get_opencode_providers'
	...ev/neovim-dev/opencode.nvim/lua/opencode/config_file.lua:61: in function 'get_model_info'
	.../Dev/neovim-dev/opencode.nvim/lua/opencode/ui/topbar.lua:19: in function 'format_token_info'
	.../Dev/neovim-dev/opencode.nvim/lua/opencode/ui/topbar.lua:105: in function <.../Dev/neovim-dev/opencode.nvim/lua/opencode/ui/topbar.lua:93>

To fully fix it, we'll have to update those places to not use wait in the common path so the nvim UI is never blocked.

sudo-tee · 2025-12-05T19:37:17Z

Good point, I think the "real" way of doing it would be to have a promise based on coroutines.. but it would require a bigger refactor. I will check the usages of :wait and see if it's possible to continue without blocking the ui or to manage the promise.

sudo-tee · 2025-12-05T20:42:25Z

@cameronr I had a look at eliminating the :wait on the critical path.

The isssue I have is that promises are spreading and need to be changed everywhere. I gave up after a couple of hours.

If you want to have a jab at it don't hesitate. I will try to find another solution to avoid calling :wait.

cameronr · 2025-12-06T16:24:04Z

Good point, I think the "real" way of doing it would be to have a promise based on coroutines.. but it would require a bigger refactor. I will check the usages of :wait and see if it's possible to continue without blocking the ui or to manage the promise.

Yes, I think you're right. I'll think about it a bit and see if I can come up with anything but I suspect it would involve refactoring most of the api to take call backs rather than executing synchronously.

sudo-tee · 2025-12-08T17:34:23Z

@cameronr

Just so you know I'm in the middle of the process of converting every promise into a coroutine. It will take a moment, but I think it will improve and cleanup a lot of stuff.

cameronr · 2025-12-08T17:36:12Z

oh great! switching to coroutines was what i was going to explore so that sounds good!

This uses coroutines for managing promises. The sync :wait method is still used in some not critical parts where it's not obvious to change to the await method

Copilot

Pull request overview

Copilot reviewed 32 out of 32 changed files in this pull request and generated 11 comments.

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lua/opencode/ui/footer.lua

lua/opencode/ui/topbar.lua

lua/opencode/ui/session_picker.lua

lua/opencode/core.lua

lua/opencode/api.lua

lua/opencode/ui/completion/engines/vim_complete.lua

lua/opencode/ui/completion/commands.lua

lua/opencode/core.lua

lua/opencode/ui/completion/engines/base.lua

cameronr · 2025-12-09T19:32:40Z

Ooh, exciting! I'll take a look today!

cameronr · 2025-12-10T00:43:17Z

I've started looking into this and you really have made great progress!

I did notice that there's still a small delay when opening the panels and I traced it down to core.opencode_ok. It seems like the opencode app has a noticeable delay now, even when running with just --version:

❯ time opencode --version
1.0.138
opencode --version  0.26s user 0.03s system 50% cpu 0.577 total

Rather than using vim.system():wait which, i believe, is blocking (even in a coroutine context), we could do something like:

-- this could be in Promise or util
local function system_async(cmd, opts)
  local p = Promise.new()

  vim.system(cmd, opts or {}, function(result)
    if result.code == 0 then
      p:resolve(result)
    else
      p:reject(result)
    end
  end)

  return p
end


M.opencode_ok = Promise.async(function()
  if vim.fn.executable('opencode') == 0 then
    vim.notify(
      'opencode command not found - please install and configure opencode before using this plugin',
      vim.log.levels.ERROR
    )
    return false
  end

  vim.notify('alive')
  if not state.opencode_cli_version or state.opencode_cli_version == '' then
    local result = system_async({ 'opencode', '--version' }):await()
    -- can test with something like:
    -- local result = system_async({ 'sleep', '3' }):await()
    local out = (result and result.stdout or ''):gsub('%s+$', '')
    state.opencode_cli_version = out:match('(%d+%%.%d+%%.%d+)') or out
    vim.notify('done: ' .. tostring(state.opencode_cli_version))
  end
  ...
end)

Let me know if it's ok to make that change.

I'll also keep looking at the changes.

sudo-tee · 2025-12-10T00:55:00Z

Great catch. Yes I am totally fine with this change

Can you run

'time opencode --version' on your system.

For me I don't see any significant delay

But the change should help anyway

cameronr · 2025-12-10T01:14:43Z

I had already included the time results in my previous comment :) Takes about 270ms:

I've started looking into this and you really have made great progress!

I did notice that there's still a small delay when opening the panels and I traced it down to core.opencode_ok. It seems like the opencode app has a noticeable delay now, even when running with just --version:
❯ time opencode --version
1.0.138
opencode --version  0.26s user 0.03s system 50% cpu 0.577 total

I'll make that change.

Caused by vim.system():wait() delay when checking opencode version. Fixed by adding Promise.system() which wraps vim.system in a promise (using vim.system's callback mechanism)

Also fix type in Promise

cameronr · 2025-12-10T01:43:24Z

I added some vim.system sleeps (to both opencode_ok and OpencodeServer:spawn to make sure it's non-blocking and it looks good:

I'll review the rest of code by tomorrow night.

sudo-tee · 2025-12-10T02:21:52Z

I had already included the time results in my previous comment :) Takes about 270ms:
I've started looking into this and you really have made great progress!

I did notice that there's still a small delay when opening the panels and I traced it down to core.opencode_ok. It seems like the opencode app has a noticeable delay now, even when running with just --version:
❯ time opencode --version
1.0.138
opencode --version  0.26s user 0.03s system 50% cpu 0.577 total
I'll make that change.

I was on mobile and didn't see it 😂

sudo-tee · 2025-12-10T12:14:13Z

lua/opencode/ui/completion/engines/base.lua

This file is not used yet,

It ended up here by error, but I plan to use it in a near feature for the completion bug.

cameronr

Looks great, only noticed some minor things.

lua/opencode/config_file.lua

lua/opencode/api.lua

lua/opencode/git_review.lua

Also, make commands_list async

sudo-tee mentioned this pull request Dec 5, 2025

UI is slow to open with opencode v1+ #133

Closed

sudo-tee requested a review from cameronr December 5, 2025 02:45

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sudo-tee added 4 commits December 5, 2025 09:06

perf: open the panel without waiting on session

897d189

fix: wrong focused window

47356e1

perf: use promise based waiting for the ensure_server

2d71c20

fix: selection context not loading before opening the panel

2bfcb8f

sudo-tee force-pushed the perf/panel-open-speed branch from e36bb46 to 2bfcb8f Compare December 5, 2025 14:07

feat: ensure we can't stay in a loading state forever

bc85505

sudo-tee force-pushed the perf/panel-open-speed branch from 49dd82c to bc85505 Compare December 8, 2025 12:16

sudo-tee force-pushed the perf/panel-open-speed branch 3 times, most recently from 9a67f66 to 4c8299a Compare December 9, 2025 12:17

refactor(promise): replace critical path with Promise.async

96e9f2d

This uses coroutines for managing promises. The sync :wait method is still used in some not critical parts where it's not obvious to change to the await method

sudo-tee force-pushed the perf/panel-open-speed branch from 4c8299a to 96e9f2d Compare December 9, 2025 13:13

fix: completion async

bfb1d76

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sudo-tee force-pushed the perf/panel-open-speed branch 9 times, most recently from 0771d43 to 9a207ac Compare December 9, 2025 16:13

fix: core review comments

e092046

sudo-tee force-pushed the perf/panel-open-speed branch from 9a207ac to e092046 Compare December 9, 2025 16:18

sudo-tee marked this pull request as ready for review December 9, 2025 16:19

cameronr added 2 commits December 9, 2025 17:19

fix(core): small delay on open

f07011d

Caused by vim.system():wait() delay when checking opencode version. Fixed by adding Promise.system() which wraps vim.system in a promise (using vim.system's callback mechanism)

test(core): fix opencode_ok tests

c941205

Also fix type in Promise

sudo-tee added 2 commits December 10, 2025 06:52

fix: context bar updates after message

40dd8e9

fix: base completion, self referencing

c019af6

sudo-tee commented Dec 10, 2025

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sudo-tee mentioned this pull request Dec 10, 2025

Slow to open Opencode window when session is really, really long. #137

Closed

cameronr reviewed Dec 10, 2025

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fix(input_window): user slash commands were broken

d0f55d6

Also, make commands_list async

sudo-tee merged commit 6094564 into main Dec 11, 2025
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perf: open the panel without waiting on session #134

perf: open the panel without waiting on session #134

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