fix(picker): align datetime column consistently in time-based pickers

lua/opencode/ui/base_picker.lua

@@ -315,9 +315,9 @@ end
 local function fzf_ui(opts)
   local fzf_lua = require('fzf-lua')
 
-  local function finder(fzf_cb, width)
+  local function finder(fzf_cb)
     for idx, item in ipairs(opts.items) do
-      local line_str = opts.format_fn(item, width):to_string()
+      local line_str = opts.format_fn(item):to_string()
 
       -- Prepend index with SOH delimiter for reliable matching
       local indexed_line = tostring(idx) .. '\x01' .. line_str
@@ -352,16 +352,6 @@ local function fzf_ui(opts)
   end
 
   local has_custom_preview = opts.preview == 'custom' and opts.preview_fn ~= nil
-  local format_width
-
-  -- defer item processing until preview if using custom preview_fn
-  -- so we can pass the width of the fzf window to the format_fn for optimal formatting
-  local width_callback = has_custom_preview
-      and function(_, _, _, ctx)
-        format_width = (ctx.env.FZF_COLUMNS or vim.o.columns) - (ctx.env.FZF_PREVIEW_COLUMNS or 0)
-        format_width = math.min(format_width, vim.o.columns - 8)
-      end
-    or nil
 
   ---@return table
   local function create_fzf_config()
@@ -370,9 +360,6 @@ local function fzf_ui(opts)
     end)
 
     return {
-      fzf_cli_args = width_callback and ('--bind=' .. require('fzf-lua.libuv').shellescape(
-        'start:+transform:' .. require('fzf-lua.shell').stringify_data(width_callback, opts)
-      )) or nil,
       winopts = opts.width and {
           width = opts.width + 8, -- extra space for fzf UI
         } or nil,
@@ -528,12 +515,7 @@ local function fzf_ui(opts)
   fzf_config.actions = actions_config
 
   fzf_lua.fzf_exec(function(fzf_cb)
-    if width_callback then
-      vim.wait(1000, function()
-        return format_width
-      end)
-    end
-    finder(fzf_cb, format_width)
+    finder(fzf_cb)
   end, fzf_config)
 end
 
@@ -813,18 +795,41 @@ function M.create_picker_item(parts)
   return item
 end
 
+---Compute the maximum formatted time width across a list of items.
+---@param items any[] The list of items
+---@param get_time_fn fun(item: any): number? Extracts a timestamp from an item
+---@return number max_width The width of the longest format_time result (0 if no valid timestamps)
+function M.max_time_width(items, get_time_fn)
+  local max_w = 0
+  for _, item in ipairs(items) do
+    local t = get_time_fn(item)
+    if t and type(t) == 'number' then
+      local w = #util.format_time(t)
+      if w > max_w then
+        max_w = w
+      end
+    end
+  end
+  return max_w
+end
+
 ---Helper function to create a simple picker item with content, time, and debug text
 ---This is a convenience wrapper around create_picker_item for common use cases
 ---@param text string Main content text
 ---@param time? number Optional time to format
 ---@param debug_text? string Optional debug text to append
 ---@param width? number Optional width override
+---@param max_time_width? number Optional pre-computed max time column width from max_time_width()
 ---@return PickerItem
-function M.create_time_picker_item(text, time, debug_text, width)
-  local time_width = time and #util.format_time(time) + 1 or 0
-  local debug_width = config.debug.show_ids and debug_text and #debug_text + 1 or 0
+function M.create_time_picker_item(text, time, debug_text, width, max_time_width)
+  local time_width = time and (max_time_width or #util.format_time(0)) or 0
+  local has_debug = config.debug.show_ids and debug_text
+  local debug_width = has_debug and #debug_text or 0
   local item_width = width or vim.api.nvim_win_get_width(0)
-  local text_width = item_width - (debug_width + time_width)
+  -- Each extra part adds a 1-char separator in to_string()/to_formatted_text(),
+  -- so subtract those from the text budget.
+  local separator_count = (time_width > 0 and 1 or 0) + (debug_width > 0 and 1 or 0)
+  local text_width = item_width - time_width - debug_width - separator_count
 
   local parts = {
     {
@@ -839,7 +844,7 @@ function M.create_time_picker_item(text, time, debug_text, width)
     })
   end
 
-  if config.debug.show_ids and debug_text then
+  if has_debug then
     table.insert(parts, {
       text = debug_text,
       highlight = 'OpencodeDebugText',

lua/opencode/ui/session_picker.lua

@@ -30,16 +30,17 @@ end
 ---Format session parts for session picker
 ---@param session Session|GlobalSession object
 ---@param width? integer
+---@param max_tw? number Pre-computed max time column width
 ---@return PickerItem
-function format_session_item(session, width)
+local function format_session_item(session, width, max_tw)
   local project = (session --[[@as GlobalSession]]).project
   local title = session.title or 'N/A'
   if project then
     local label = project.name or vim.fn.pathshorten(project.worktree) or project.id or '?'
     title = title .. '  [' .. label .. ']'
   end
   local updated_time = (session.time and session.time.updated) or 'N/A'
-  return base_picker.create_time_picker_item(title, updated_time, nil, width)
+  return base_picker.create_time_picker_item(title, updated_time, nil, width, max_tw)
 end
 
 --- Normalize message order to oldest-first (chronological)
@@ -341,9 +342,15 @@ function M.pick(sessions, callback, opts)
   -- Preview state for race condition protection
   local preview_seq = 0
 
+  local max_tw = base_picker.max_time_width(sessions, function(s)
+    return s.time and s.time.updated
+  end)
+
   return base_picker.pick({
     items = sessions,
-    format_fn = format_session_item,
+    format_fn = function(session, width)
+      return format_session_item(session, width, max_tw)
+    end,
     actions = actions,
     callback = callback,
     title = (opts and opts.scope == 'global') and 'Select A Session (all projects)' or 'Select A Session',

lua/opencode/ui/timeline_picker.lua

@@ -5,13 +5,15 @@ local base_picker = require('opencode.ui.base_picker')
 
 ---Format message parts for timeline picker
 ---@param msg OpencodeMessage Message object
+---@param width? number
+---@param max_tw? number Pre-computed max time column width
 ---@return PickerItem
-function format_message_item(msg, width)
+local function format_message_item(msg, width, max_tw)
   local preview = msg.parts and msg.parts[1] and msg.parts[1].text or ''
 
   local debug_text = 'ID: ' .. (msg.info.id or 'N/A')
 
-  return base_picker.create_time_picker_item(vim.trim(preview), msg.info.time.created, debug_text, width)
+  return base_picker.create_time_picker_item(vim.trim(preview), msg.info.time.created, debug_text, width, max_tw)
 end
 
 function M.pick(messages, callback)
@@ -35,9 +37,15 @@ function M.pick(messages, callback)
     },
   }
 
+  local max_tw = base_picker.max_time_width(messages, function(msg)
+    return msg.info and msg.info.time and msg.info.time.created
+  end)
+
   return base_picker.pick({
     items = messages,
-    format_fn = format_message_item,
+    format_fn = function(msg, width)
+      return format_message_item(msg, width, max_tw)
+    end,
     actions = actions,
     callback = callback,
     title = 'Timeline',

tests/unit/base_picker_spec.lua

@@ -252,8 +252,6 @@ describe('opencode.ui.base_picker fzf-lua preview', function()
       ['opencode.ui.picker'] = package.loaded['opencode.ui.picker'],
       ['opencode.ui.base_picker'] = package.loaded['opencode.ui.base_picker'],
       ['fzf-lua'] = package.loaded['fzf-lua'],
-      ['fzf-lua.libuv'] = package.loaded['fzf-lua.libuv'],
-      ['fzf-lua.shell'] = package.loaded['fzf-lua.shell'],
       ['fzf-lua.previewer.builtin'] = package.loaded['fzf-lua.previewer.builtin'],
     }
 
@@ -295,7 +293,6 @@ describe('opencode.ui.base_picker fzf-lua preview', function()
 
     captured_fzf_finder = nil
     captured_fzf_opts = nil
-    captured_transform = nil
 
     package.loaded['fzf-lua'] = {
       fzf_exec = function(finder, opts)
@@ -305,18 +302,6 @@ describe('opencode.ui.base_picker fzf-lua preview', function()
     }
 
     next_preview_buf = nil
-    package.loaded['fzf-lua.libuv'] = {
-      shellescape = function(s)
-        return s
-      end,
-    }
-
-    package.loaded['fzf-lua.shell'] = {
-      stringify_data = function(fn)
-        captured_transform = fn
-        return ''
-      end,
-    }
 
     package.loaded['fzf-lua.previewer.builtin'] = {
       buffer_or_file = {
@@ -429,10 +414,179 @@ describe('opencode.ui.base_picker fzf-lua preview', function()
       end
     end)
 
-    captured_transform(nil, nil, nil, { env = { FZF_COLUMNS = 31 } })
-
+    -- picker_width=80 with preview: window=80+8=88, list pane=floor(88*0.4)-4=31
     assert.equal(31, observed_width)
     assert.are.same({ '1\001session' }, emitted_lines)
     assert.equal(88, captured_fzf_opts.winopts.width)
   end)
 end)
+
+describe('opencode.ui.base_picker create_time_picker_item alignment', function()
+  local base_picker
+  local original_schedule
+  local saved_modules
+  local mock_config
+
+  before_each(function()
+    original_schedule = vim.schedule
+    vim.schedule = function(fn)
+      fn()
+    end
+
+    saved_modules = {
+      ['opencode.config'] = package.loaded['opencode.config'],
+      ['opencode.util'] = package.loaded['opencode.util'],
+      ['opencode.promise'] = package.loaded['opencode.promise'],
+      ['opencode.ui.picker'] = package.loaded['opencode.ui.picker'],
+      ['opencode.ui.base_picker'] = package.loaded['opencode.ui.base_picker'],
+    }
+
+    mock_config = {
+      ui = {
+        picker_width = 80,
+        output = { time_format = nil },
+      },
+      debug = { show_ids = false },
+    }
+    package.loaded['opencode.config'] = mock_config
+
+    -- Provide a format_time that mimics real behavior: variable-width output
+    -- depending on how old the timestamp is relative to "now".
+    package.loaded['opencode.util'] = {
+      format_time = function(timestamp)
+        if not timestamp then
+          return ''
+        end
+        local now = os.time()
+        local same_day = os.date('%Y-%m-%d') == os.date('%Y-%m-%d', timestamp)
+        local same_year = os.date('%Y') == os.date('%Y', timestamp)
+        local time_part = os.date('%H:%M', timestamp)
+        if same_day then
+          return time_part -- e.g. "10:35"
+        elseif same_year then
+          return os.date('%d %b', timestamp) .. ' ' .. time_part -- e.g. "09 Jun 10:35"
+        else
+          return os.date('%d %b %Y', timestamp) .. ' ' .. time_part -- e.g. "09 Jun 2024 10:35"
+        end
+      end,
+    }
+
+    package.loaded['opencode.promise'] = {
+      wrap = function(value)
+        return {
+          and_then = function(_, cb)
+            cb(value)
+          end,
+        }
+      end,
+    }
+
+    package.loaded['opencode.ui.picker'] = {
+      get_best_picker = function()
+        return 'snacks'
+      end,
+    }
+
+    package.loaded['opencode.ui.base_picker'] = nil
+    base_picker = require('opencode.ui.base_picker')
+  end)
+
+  after_each(function()
+    vim.schedule = original_schedule
+    for module_name, module_value in pairs(saved_modules) do
+      package.loaded[module_name] = module_value
+    end
+  end)
+
+  it('produces identical total width for timestamps of different ages', function()
+    local now = os.time()
+    local same_day_ts = now - 3600 -- 1 hour ago
+    local same_year_ts = now - 86400 * 60 -- ~2 months ago
+    local diff_year_ts = 0 -- epoch (1970)
+
+    local width = 80
+    local format_time = package.loaded['opencode.util'].format_time
+    local max_tw = math.max(#format_time(same_day_ts), #format_time(same_year_ts), #format_time(diff_year_ts))
+
+    local item_today = base_picker.create_time_picker_item('Session A', same_day_ts, nil, width, max_tw)
+    local item_month = base_picker.create_time_picker_item('Session B', same_year_ts, nil, width, max_tw)
+    local item_old = base_picker.create_time_picker_item('Session C', diff_year_ts, nil, width, max_tw)
+
+    local str_today = item_today:to_string()
+    local str_month = item_month:to_string()
+    local str_old = item_old:to_string()
+
+    assert.equal(#str_today, #str_month, 'same-day and same-year items should have equal width')
+    assert.equal(#str_today, #str_old, 'same-day and different-year items should have equal width')
+  end)
+
+  it('to_string width matches the requested item width exactly', function()
+    local width = 60
+
+    local item = base_picker.create_time_picker_item('Session Title', 0, nil, width)
+    local str = item:to_string()
+
+    assert.equal(width, #str, 'to_string() output should be exactly item_width chars')
+  end)
+
+  it('right-aligns time within a fixed-width column', function()
+    local now = os.time()
+    local same_day_ts = now - 3600
+
+    local width = 80
+    local max_tw = #package.loaded['opencode.util'].format_time(same_day_ts)
+    local item = base_picker.create_time_picker_item('Title', same_day_ts, nil, width, max_tw)
+    local str = item:to_string()
+
+    local time_str = package.loaded['opencode.util'].format_time(same_day_ts)
+    assert.is_truthy(str:match(time_str .. '$'), 'time string should be at the right edge')
+  end)
+
+  it('max_time_width returns the width of the longest formatted timestamp', function()
+    local now = os.time()
+    local items = {
+      { time = now - 3600 }, -- same-day
+      { time = now - 86400 * 60 }, -- same-year
+      { time = 0 }, -- different year (longest)
+    }
+
+    local max_tw = base_picker.max_time_width(items, function(item)
+      return item.time
+    end)
+
+    local format_time = package.loaded['opencode.util'].format_time
+    local expected = math.max(#format_time(items[1].time), #format_time(items[2].time), #format_time(items[3].time))
+    assert.equal(expected, max_tw)
+  end)
+
+  it('max_time_width returns 0 for empty items', function()
+    local max_tw = base_picker.max_time_width({}, function(item)
+      return item.time
+    end)
+    assert.equal(0, max_tw)
+  end)
+
+  it('max_time_width returns 0 when no items have timestamps', function()
+    local items = { { name = 'a' }, { name = 'b' } }
+    local max_tw = base_picker.max_time_width(items, function(item)
+      return item.time -- nil
+    end)
+    assert.equal(0, max_tw)
+  end)
+
+  it('uses only same-day width when all timestamps are from today', function()
+    local now = os.time()
+    local items = {
+      { time = now - 60 },
+      { time = now - 3600 },
+    }
+
+    local max_tw = base_picker.max_time_width(items, function(item)
+      return item.time
+    end)
+
+    local format_time = package.loaded['opencode.util'].format_time
+    -- All same-day, so max_tw should equal the short time width
+    assert.equal(#format_time(now - 60), max_tw)
+  end)
+end)