Keep panes and gutters aligned under a winbar

lua/diffbandit/folder/init.lua

@@ -4,6 +4,7 @@ local nvim = require("diffbandit.util.nvim")
 local process = require("diffbandit.util.process")
 local ui = require("diffbandit.util.ui")
 local layout = require("diffbandit.util.layout")
+local winbar = require("diffbandit.util.winbar")
 local config_mod = require("diffbandit.config")
 
 local Folder = {}
@@ -419,6 +420,7 @@ function Folder:open_layout()
   end
   set_window_options(gutter_win, layout.win_opts.gutter())
   set_window_width(gutter_win, self.gutter_width)
+  winbar.align(self:winbar_spec())
   self:resize_layout()
   vim.api.nvim_set_current_win(left_win)
   self.title = string.format("DiffBandit Folder: %s ↔ %s", self.left_root, self.right_root)
@@ -981,6 +983,11 @@ function Folder:run_digest_batch(batch, generation)
   end)
 end
 
+-- The windows whose rows line up under a winbar (see util/winbar).
+function Folder:winbar_spec()
+  return { content = { self.left_win, self.right_win }, gutters = { self.gutter_win } }
+end
+
 function Folder:setup_autocmds()
   local augroup = vim.api.nvim_create_augroup("DiffBanditFolder" .. tostring(self.id), { clear = true })
   self.autocmd_group = augroup
@@ -1001,6 +1008,11 @@ function Folder:setup_autocmds()
       end,
     })
   end
+  winbar.watch(self, function()
+    return self:winbar_spec()
+  end, function()
+    self:render()
+  end)
   vim.api.nvim_create_autocmd({ "VimResized", "WinResized" }, {
     group = augroup,
     callback = function()

lua/diffbandit/kitty/canvas.lua

@@ -15,6 +15,7 @@ local detect = require("diffbandit.kitty.detect")
 local ids = require("diffbandit.kitty.ids")
 local protocol = require("diffbandit.kitty.protocol")
 local raster = require("diffbandit.kitty.raster")
+local winbar = require("diffbandit.util.winbar")
 local zlib = require("diffbandit.kitty.zlib")
 
 local M = {}
@@ -140,7 +141,7 @@ function M.layout(host)
   local right_edge = win_col(sr.win) + sr.col
   local cols = right_edge - left_edge + 1
   local core_start = win_col(host.connector_win) - left_edge
-  local rows = math.min(vim.api.nvim_win_get_height(host.connector_win), protocol.MAX_INDEX + 1)
+  local rows = math.min(vim.fn.winheight(host.connector_win), protocol.MAX_INDEX + 1)
   if cols < 1 or cols > protocol.MAX_INDEX + 1 or rows < 1 or core_start < 0 then
     return nil
   end
@@ -207,6 +208,16 @@ local function transmit(host, st, bytes, width, height, layout)
       medium = "d", data = payload, compressed = compressed, quiet = 1,
     })
   end
+  -- Re-sending an image id with a new cell grid (c/r) does not resize its
+  -- existing virtual placement in every terminal: Ghostty keeps the old
+  -- grid and stretches the new image over it, so the ribbons drift further
+  -- off the further down they are (a winbar or resize taking one row). Drop
+  -- the old image and placement first whenever the grid changes.
+  local grid = layout.cols .. "x" .. layout.rows
+  if st.placed_grid and st.placed_grid ~= grid then
+    table.insert(chunks, 1, protocol.delete(st.id))
+  end
+  st.placed_grid = grid
   st.transmits = st.transmits + 1
   local ok = detect.send(chunks)
   detect.note_transmit()
@@ -522,8 +533,11 @@ local function ensure_float(host, st, layout)
   -- Editor-relative at the connector's screen row and the screen-left wedge
   -- column (relative="win" floats mis-position under some grids); paint
   -- re-checks the position every time, so layout changes follow on the
-  -- next render.
+  -- next render. The window position is its top row, which is the winbar
+  -- when it has one (util/winbar keeps the bar uniform across the panes);
+  -- the ribbons start at the first text row below it.
   local row = vim.api.nvim_win_get_position(host.connector_win)[1]
+    + winbar.rows(host.connector_win)
   local col = vim.api.nvim_win_get_position(layout.screen_left.win)[2] + layout.screen_left.col
   local cfg = {
     relative = "editor",

lua/diffbandit/merge/init.lua

@@ -4,6 +4,7 @@ local merge_model = require("diffbandit.merge.model")
 local nvim = require("diffbandit.util.nvim")
 local keymaps = require("diffbandit.util.keymaps")
 local layout = require("diffbandit.util.layout")
+local winbar = require("diffbandit.util.winbar")
 local document = require("diffbandit.util.document")
 local pair_renderer = require("diffbandit.merge.pair_renderer")
 local panel_mod = require("diffbandit.panel")
@@ -325,6 +326,22 @@ function Merge.start_for_path(path, opts, config)
   return Merge.start(data, config, opts)
 end
 
+-- The windows whose rows line up under a winbar (see util/winbar).
+function Merge:winbar_spec()
+  return {
+    content = { self.local_win, self.result_win, self.remote_win },
+    gutters = {
+      self.local_num_win,
+      self.local_result_connector_win,
+      self.result_left_num_win,
+      self.result_right_num_win,
+      self.result_remote_connector_win,
+      self.remote_num_win,
+    },
+    headers = { self.local_header_win, self.result_header_win, self.remote_header_win },
+  }
+end
+
 function Merge:configure_windows()
   for _, win in ipairs({ self.local_win, self.result_win, self.remote_win }) do
     if win and vim.api.nvim_win_is_valid(win) then
@@ -383,11 +400,7 @@ function Merge:configure_windows()
     set_win_width(self.remote_header_win,
       content_width + (remote_visible and (num_pane_width + core_width) or 0))
   end
-  for _, win in ipairs({ self.local_win, self.result_win, self.remote_win }) do
-    if win and vim.api.nvim_win_is_valid(win) then
-      pcall(vim.api.nvim_set_option_value, "winbar", "", { scope = "local", win = win })
-    end
-  end
+  winbar.align(self:winbar_spec())
   if self.panel then
     local panel_config = config_mod.section(self.config, "git", "panel")
     for _, win in ipairs({ self.panel.nav_win, self.panel.commit_win }) do
@@ -514,6 +527,14 @@ function Merge:setup_autocmds()
     group = self.augroup,
     callback = reassert_merge_maps,
   })
+  -- Breadcrumb plugins set a pane's winbar lazily; keep the gutters on the
+  -- same bar row.
+  winbar.watch(self, function()
+    return self:winbar_spec()
+  end, function()
+    self:sync_gutter_viewports()
+    self:render()
+  end)
   -- The three content panes scroll independently; DiffBandit owns gutter
   -- synchronization (same contract as two-way sessions — no scrollbind).
   vim.api.nvim_create_autocmd("WinScrolled", {
@@ -1652,9 +1673,9 @@ function Merge:goto_document_edge(edge)
   local local_count = math.max(1, vim.api.nvim_buf_line_count(self.local_buf))
   local result_count = math.max(1, vim.api.nvim_buf_line_count(self.result_buf))
   local remote_count = math.max(1, vim.api.nvim_buf_line_count(self.remote_buf))
-  local local_height = self.local_win and vim.api.nvim_win_is_valid(self.local_win) and vim.api.nvim_win_get_height(self.local_win) or 1
-  local result_height = self.result_win and vim.api.nvim_win_is_valid(self.result_win) and vim.api.nvim_win_get_height(self.result_win) or 1
-  local remote_height = self.remote_win and vim.api.nvim_win_is_valid(self.remote_win) and vim.api.nvim_win_get_height(self.remote_win) or 1
+  local local_height = self.local_win and vim.api.nvim_win_is_valid(self.local_win) and nvim.get_window_height(self.local_win) or 1
+  local result_height = self.result_win and vim.api.nvim_win_is_valid(self.result_win) and nvim.get_window_height(self.result_win) or 1
+  local remote_height = self.remote_win and vim.api.nvim_win_is_valid(self.remote_win) and nvim.get_window_height(self.remote_win) or 1
 
   local local_line = edge == "bottom" and local_count or 1
   local result_line = edge == "bottom" and result_count or 1

lua/diffbandit/session/init.lua

@@ -16,6 +16,7 @@ local config_mod = require("diffbandit.config")
 local view_builder = require("diffbandit.diff.view")
 local diff_document = require("diffbandit.diff.document")
 local kitty = require("diffbandit.kitty")
+local winbar = require("diffbandit.util.winbar")
 
 local Session = {}
 Session.__index = Session
@@ -232,8 +233,8 @@ function Session:render_overviews()
     return
   end
 
-  local left_height = math.max(1, vim.api.nvim_win_get_height(self.left_win))
-  local right_height = math.max(1, vim.api.nvim_win_get_height(self.right_win))
+  local left_height = math.max(1, nvim.get_window_height(self.left_win))
+  local right_height = math.max(1, nvim.get_window_height(self.right_win))
   local left_cursor = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_cursor(self.left_win)[1] or 1
   local right_cursor = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_cursor(self.right_win)[1] or 1
 
@@ -268,7 +269,7 @@ function Session:get_scroll_padding()
   local wins = { self.left_win, self.right_win, self.connector_win }
   for _, win in ipairs(wins) do
     if win and vim.api.nvim_win_is_valid(win) then
-      height = math.max(height, vim.api.nvim_win_get_height(win))
+      height = math.max(height, nvim.get_window_height(win))
     end
   end
   return math.max(0, height - 1)
@@ -387,6 +388,15 @@ function Session:setup_autocmds()
     end,
   })
 
+  -- A winbar set on a source pane after open (breadcrumb plugins attach
+  -- lazily) moves its text a row down; give the gutters the same bar row.
+  winbar.watch(self, function()
+    return session_layout.winbar_spec(self)
+  end, function()
+    self:sync_gutter_viewports()
+    self:render()
+  end)
+
   vim.api.nvim_create_autocmd("WinScrolled", {
     group = augroup,
     callback = function(event)
@@ -872,8 +882,8 @@ function Session:align_chunk_viewports(chunk)
   -- keeps the UI responsive and coalesces repaints. Long jumps outside the
   -- window render synchronously so no unstyled rows ever appear.
   local clip = self.last_render_clip
-  local left_height = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_height(self.left_win) or 1
-  local right_height = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_height(self.right_win) or 1
+  local left_height = vim.api.nvim_win_is_valid(self.left_win) and nvim.get_window_height(self.left_win) or 1
+  local right_height = vim.api.nvim_win_is_valid(self.right_win) and nvim.get_window_height(self.right_win) or 1
   local within_styled_window = clip ~= nil
     and left_topline >= clip.left_min
     and (left_topline + left_height) <= clip.left_max
@@ -942,8 +952,8 @@ function Session:goto_document_edge(edge)
   local right_line_count = math.max(1, #self.view.right)
   local left_line = edge == "bottom" and left_line_count or 1
   local right_line = edge == "bottom" and right_line_count or 1
-  local left_height = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_height(self.left_win) or 1
-  local right_height = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_height(self.right_win) or 1
+  local left_height = vim.api.nvim_win_is_valid(self.left_win) and nvim.get_window_height(self.left_win) or 1
+  local right_height = vim.api.nvim_win_is_valid(self.right_win) and nvim.get_window_height(self.right_win) or 1
   local left_topline = edge == "bottom" and math.max(1, left_line_count - left_height + 1) or 1
   local right_topline = edge == "bottom" and math.max(1, right_line_count - right_height + 1) or 1
 

lua/diffbandit/session/layout.lua

@@ -6,6 +6,7 @@ local nvim = require("diffbandit.util.nvim")
 local document = require("diffbandit.util.document")
 local config_mod = require("diffbandit.config")
 local layout = require("diffbandit.util.layout")
+local winbar = require("diffbandit.util.winbar")
 
 local set_buffer_options = nvim.set_buffer_options
 local set_window_options = nvim.set_window_options
@@ -240,11 +241,27 @@ end
 -- queue) silently reverts them to that buffer's defaults — 'wrap' coming
 -- back on desyncs the pane's screen rows from its unwrappable gutters,
 -- and 'scrolloff'/folds undo ]c alignment. Re-apply after every right-buffer swap.
+-- The windows whose rows line up under a winbar (see util/winbar).
+local function winbar_spec(session)
+  return {
+    content = { session.left_win, session.right_win },
+    gutters = {
+      session.left_overview_win,
+      session.left_num_win,
+      session.connector_win,
+      session.right_num_win,
+      session.right_overview_win,
+    },
+    headers = { session.left_header_win, session.center_header_win, session.right_header_win },
+  }
+end
+
 local function apply_right_source_window_options(session)
   local right_source_winhl = session.overview_enabled and layout.winhl.hidden_source or layout.winhl.source
   set_window_options(session.right_win, layout.win_opts.source(right_source_winhl, {
     signcolumn = session.right.editable and "auto" or "no",
   }))
+  winbar.align(winbar_spec(session))
 end
 
 local function apply_window_options(session)
@@ -341,6 +358,8 @@ function M.apply_right_source_window_options(session)
   apply_right_source_window_options(session)
 end
 
+M.winbar_spec = winbar_spec
+
 function M.open(session)
   vim.cmd("tabnew")
   session.tabpage = vim.api.nvim_get_current_tabpage()

lua/diffbandit/session/render.lua

@@ -234,15 +234,15 @@ local function build_render_context(self)
   local left_lines, right_lines = self:display_lines()
   local left_topline = get_win_view_topline(self.left_win)
   local right_topline = get_win_view_topline(self.right_win)
-  local left_height = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_height(self.left_win) or 1
+  local left_height = vim.api.nvim_win_is_valid(self.left_win) and nvim.get_window_height(self.left_win) or 1
   local right_text_hl_mode = self.right.editable and "combine" or "replace"
 
   -- Compute connector routing lanes using extracted paths module. Projection
   -- and planning are the most expensive render stages, and both are pure
   -- functions of the viewport state — cache per state so revisited viewports
   -- (navigation back and forth, debounced duplicate repaints) are free.
   local paths = self:base_paths()
-  local win_height = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_height(self.right_win) or 1
+  local win_height = vim.api.nvim_win_is_valid(self.right_win) and nvim.get_window_height(self.right_win) or 1
   local kitty = kitty_mode(self)
   local plan_cache_key = string.format("%s:%s:%d:%d:%d:%d%s",
     tostring(left_topline), tostring(right_topline), left_height, win_height,

lua/diffbandit/session/render_host.lua

@@ -18,8 +18,8 @@ local get_win_view_topline = nvim.get_win_view_topline
 local function live_viewport_render_key(self)
   local left_topline = get_win_view_topline(self.left_win)
   local right_topline = get_win_view_topline(self.right_win)
-  local left_height = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_height(self.left_win) or 1
-  local right_height = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_height(self.right_win) or 1
+  local left_height = vim.api.nvim_win_is_valid(self.left_win) and nvim.get_window_height(self.left_win) or 1
+  local right_height = vim.api.nvim_win_is_valid(self.right_win) and nvim.get_window_height(self.right_win) or 1
   return ui.viewport_render_key(left_topline, right_topline, left_height, right_height, self.current_chunk)
 end
 
@@ -275,8 +275,8 @@ end
 function M.project_paths_for_viewport(self, paths)
   local left_topline = get_win_view_topline(self.left_win)
   local right_topline = get_win_view_topline(self.right_win)
-  local left_height = vim.api.nvim_win_is_valid(self.left_win) and vim.api.nvim_win_get_height(self.left_win) or 1
-  local right_height = vim.api.nvim_win_is_valid(self.right_win) and vim.api.nvim_win_get_height(self.right_win) or 1
+  local left_height = vim.api.nvim_win_is_valid(self.left_win) and nvim.get_window_height(self.left_win) or 1
+  local right_height = vim.api.nvim_win_is_valid(self.right_win) and nvim.get_window_height(self.right_win) or 1
   return self:project_paths_for_toplines(paths, left_topline, right_topline, left_height, right_height)
 end
 
@@ -288,7 +288,7 @@ function M.precompute_connector_core_width(self)
     required_core = require("diffbandit.kitty").core_width(self.config)
   else
     local viewport_rows = vim.api.nvim_win_is_valid(self.left_win)
-        and vim.api.nvim_win_get_height(self.left_win) or nil
+        and nvim.get_window_height(self.left_win) or nil
     required_core = connector.pressure_core_width(
       self:base_paths(),
       connector_width.base(self.view, self.config),

lua/diffbandit/util/layout.lua

@@ -36,11 +36,14 @@ M.winhl = {
   source = split .. ",CursorLine:DiffBanditCursorLine,SignColumn:DiffBanditSignColumn",
   hidden_source = hidden_split .. ",CursorLine:DiffBanditCursorLine,SignColumn:DiffBanditSignColumn",
   gutter = "Normal:DiffBanditConnectorContext,NormalNC:DiffBanditConnectorContext,"
+    .. "WinBar:DiffBanditConnectorContext,WinBarNC:DiffBanditConnectorContext,"
     .. split .. ",CursorLine:DiffBanditCursorLine",
   overview = "Normal:DiffBanditOverviewContext,NormalNC:DiffBanditOverviewContext,"
+    .. "WinBar:DiffBanditOverviewContext,WinBarNC:DiffBanditOverviewContext,"
     .. hidden_split .. ",CursorLine:DiffBanditCursorLine",
   status = "Normal:DiffBanditStatus,NormalNC:DiffBanditStatus,"
     .. "StatusLine:DiffBanditStatusLine,StatusLineNC:DiffBanditStatusLine,"
+    .. "WinBar:DiffBanditStatus,WinBarNC:DiffBanditStatus,"
     .. split .. ",CursorLine:DiffBanditStatus",
   panel = split .. ",Normal:DiffBanditStatus,NormalNC:DiffBanditStatus,CursorLine:DiffBanditCursorLine",
 }

lua/diffbandit/util/nvim.lua

@@ -55,9 +55,11 @@ function M.get_window_width(win)
   return 0
 end
 
+-- Text rows of a window. nvim_win_get_height counts the winbar row too;
+-- every DiffBandit viewport computation means the rows code is drawn on.
 function M.get_window_height(win)
   if win and vim.api.nvim_win_is_valid(win) then
-    return vim.api.nvim_win_get_height(win)
+    return math.max(0, vim.fn.winheight(win))
   end
   return 0
 end