diff --git a/README.md b/README.md
index ff2936d2..a427ce5e 100644
--- a/README.md
+++ b/README.md
@@ -393,6 +393,8 @@ require('opencode').setup({
     on_done_thinking = nil, -- Called when a session becomes idle, including sessions started outside Neovim.
     on_permission_requested = nil, -- Called when a permission request is issued.
     on_question_asked = nil, -- Called when a question is asked.
+    on_topbar_render = nil, -- Transform topbar segments; return nil to clear topbar.
+    on_footer_render = nil, -- Transform footer segments; return nil to clear footer.
   },
   quick_chat = {
     default_model = nil,   -- works better with a fast model like gpt-4.1
@@ -1294,6 +1296,10 @@ You can define custom functions to be called at specific events in Opencode:
 - `on_done_thinking`: Called when a session becomes idle, including sessions started outside Neovim.
 - `on_permission_requested`: Called when a permission request is issued.
 - `on_question_asked`: Called when a question is asked.
+- `on_topbar_render`: Receives topbar segments on each render and returns updated segments.
+- `on_footer_render`: Receives footer segments on each render and returns updated segments.
+
+Segments use `{ 'text', 'HighlightGroup', align = 'left'|'right' }`; highlight and alignment are optional, and alignment defaults to `'left'`. Right-aligned segments render after the bar's spacer. Return `nil` to clear that bar. If a hook errors, built-in segments render unchanged.
 
 ```lua
 require('opencode').setup({
@@ -1320,6 +1326,11 @@ require('opencode').setup({
       -- Custom logic when a question is asked
       print("Question asked in session " .. session.id)
     end,
+    on_footer_render = function(segments)
+      -- Add project context to the footer's left side.
+      table.insert(segments, 1, { 'repo:branch ', 'OpencodeHint' })
+      return segments
+    end,
   },
 })
 ```
diff --git a/lua/opencode/config.lua b/lua/opencode/config.lua
index a52500d2..7515be43 100644
--- a/lua/opencode/config.lua
+++ b/lua/opencode/config.lua
@@ -396,6 +396,8 @@ M.defaults = {
     on_done_thinking = nil,
     on_permission_requested = nil,
     on_question_asked = nil,
+    on_topbar_render = nil,
+    on_footer_render = nil,
   },
   quick_chat = {
     default_model = nil,
diff --git a/lua/opencode/types.lua b/lua/opencode/types.lua
index fdacc27e..2da1b4b2 100644
--- a/lua/opencode/types.lua
+++ b/lua/opencode/types.lua
@@ -362,7 +362,11 @@
 ---@class OpencodeCommandHookRegisterOptions
 ---@field command? OpencodeCommandHookScope
 
+---@alias OpencodeBarSegment { [1]: string, [2]?: string, align?: 'left'|'right' }
+---@alias OpencodeBarSegmentsHook fun(segments: OpencodeBarSegment[]): OpencodeBarSegment[]|nil
 ---@class OpencodeHooks
+---@field on_topbar_render? OpencodeBarSegmentsHook
+---@field on_footer_render? OpencodeBarSegmentsHook
 ---@field on_file_edited? fun(file: string): nil
 ---@field on_session_loaded? fun(session: OpencodeSession): nil
 ---@field on_done_thinking? fun(session: OpencodeSession): nil Called when a session becomes idle.
diff --git a/lua/opencode/ui/footer.lua b/lua/opencode/ui/footer.lua
index d521648f..d918030f 100644
--- a/lua/opencode/ui/footer.lua
+++ b/lua/opencode/ui/footer.lua
@@ -58,6 +58,39 @@ local function build_right_segments()
   return segments
 end
 
+---@param hook OpencodeBarSegmentsHook|nil
+---@param segments OpencodeBarSegment[]
+---@return OpencodeBarSegment[]|nil
+local function apply_segments_hook(hook, segments)
+  if not hook then
+    return segments
+  end
+
+  local ok, transformed = pcall(hook, vim.deepcopy(segments))
+  if not ok then
+    return segments
+  end
+
+  return transformed
+end
+
+---@param segments OpencodeBarSegment[]
+---@return OpencodeBarSegment[], OpencodeBarSegment[]
+local function split_segments(segments)
+  local left_segments = {}
+  local right_segments = {}
+
+  for _, segment in ipairs(segments) do
+    if segment.align == 'right' then
+      table.insert(right_segments, segment)
+    else
+      table.insert(left_segments, segment)
+    end
+  end
+
+  return left_segments, right_segments
+end
+
 local function add_segments(segments, parts, highlights, col)
   for _, segment in ipairs(segments) do
     local text = segment[1]
@@ -112,8 +145,19 @@ function M.render()
     return
   end
 
-  local left_segments = build_left_segments()
-  local right_segments = build_right_segments()
+  local segments = build_left_segments()
+  for _, segment in ipairs(build_right_segments()) do
+    segment.align = 'right'
+    table.insert(segments, segment)
+  end
+
+  local transformed_segments = apply_segments_hook(config.hooks.on_footer_render, segments)
+  if transformed_segments == nil then
+    M.set_content({})
+    return
+  end
+
+  local left_segments, right_segments = split_segments(transformed_segments)
   local win_width = vim.api.nvim_win_get_width(state.windows.output_win --[[@as integer]])
 
   local footer_text, highlights = build_footer_from_segments(left_segments, right_segments, win_width)
diff --git a/lua/opencode/ui/topbar.lua b/lua/opencode/ui/topbar.lua
index 7e902149..6d577d25 100644
--- a/lua/opencode/ui/topbar.lua
+++ b/lua/opencode/ui/topbar.lua
@@ -67,13 +67,44 @@ local function format_token_info()
     end
   end
 
-  local result = table.concat(parts, ' | ')
-  result = result:gsub('%%', '%%%%')
-  return result
+  return table.concat(parts, ' | ')
 end
 
-local function create_winbar_text(description, token_info, _)
-  return description .. '%=' .. token_info
+---@param hook OpencodeBarSegmentsHook|nil
+---@param segments OpencodeBarSegment[]
+---@return OpencodeBarSegment[]|nil
+local function apply_segments_hook(hook, segments)
+  if not hook then
+    return segments
+  end
+
+  local ok, transformed = pcall(hook, vim.deepcopy(segments))
+  if not ok then
+    return segments
+  end
+
+  return transformed
+end
+
+---@param segments OpencodeBarSegment[]
+local function create_winbar_text(segments)
+  local left_parts = {}
+  local right_parts = {}
+
+  for _, segment in ipairs(segments) do
+    local text = segment[1]:gsub('%%', '%%%%')
+    if segment[2] then
+      text = '%#' .. segment[2] .. '#' .. text .. '%*'
+    end
+
+    if segment.align == 'right' then
+      table.insert(right_parts, text)
+    else
+      table.insert(left_parts, text)
+    end
+  end
+
+  return table.concat(left_parts) .. '%=' .. table.concat(right_parts)
 end
 
 local function get_session_desc()
@@ -110,10 +141,14 @@ function M.render()
       return
     end
 
-    local desc = get_session_desc():gsub('%%', '%%%%')
+    local desc = get_session_desc()
     local token_info = format_token_info()
-    local winbar_str = create_winbar_text(desc, token_info, vim.api.nvim_win_get_width(win))
-    vim.wo[win].winbar = winbar_str
+    local segments = apply_segments_hook(config.hooks.on_topbar_render, {
+      { desc },
+      { token_info, align = 'right' },
+    })
+    -- An empty local winbar inherits the global value instead of clearing the bar.
+    vim.wo[win].winbar = segments and create_winbar_text(segments) or '%='
 
     winbar.update_highlights(win, 'OpencodeSessionDescription')
   end)
diff --git a/tests/unit/bar_segments_spec.lua b/tests/unit/bar_segments_spec.lua
new file mode 100644
index 00000000..2ac7c2be
--- /dev/null
+++ b/tests/unit/bar_segments_spec.lua
@@ -0,0 +1,99 @@
+local config = require('opencode.config')
+local helpers = require('tests.helpers')
+local state = require('opencode.state')
+local store = require('opencode.state.store')
+local footer = require('opencode.ui.footer')
+local topbar = require('opencode.ui.topbar')
+local ui = require('opencode.ui.ui')
+
+describe('bar segment hooks', function()
+  local original_state
+  local original_hooks
+  local original_winbar
+
+  before_each(function()
+    original_state = vim.deepcopy(store.state())
+    original_hooks = config.hooks
+    original_winbar = vim.api.nvim_get_option_value('winbar', { scope = 'global' })
+    config.hooks = vim.deepcopy(config.hooks)
+    helpers.replay_setup()
+  end)
+
+  after_each(function()
+    topbar.close()
+    if state.windows then
+      ui.close_windows(state.windows)
+    end
+    config.hooks = original_hooks
+    vim.api.nvim_set_option_value('winbar', original_winbar, { scope = 'global' })
+    for key, value in pairs(original_state) do
+      store.set_raw(key, value)
+    end
+  end)
+
+  it('lets topbar hook prepend a styled segment', function()
+    config.hooks.on_topbar_render = function(segments)
+      table.insert(segments, 1, { 'project ', 'OpencodeHint' })
+      return segments
+    end
+    topbar.render()
+
+    assert.is_true(vim.wait(1000, function()
+      local winbar = vim.wo[state.windows.output_win].winbar
+      return winbar:find('project ', 1, true) ~= nil and winbar:find('New session', 1, true) ~= nil
+    end))
+  end)
+
+  it('clears topbar when hook returns nil', function()
+    config.hooks.on_topbar_render = function()
+      return nil
+    end
+
+    topbar.render()
+
+    assert.is_true(vim.wait(1000, function()
+      return vim.wo[state.windows.output_win].winbar == '%='
+    end))
+  end)
+
+  it('suppresses the global winbar when hook returns nil', function()
+    vim.api.nvim_set_option_value('winbar', 'Global winbar', { scope = 'global' })
+    config.hooks.on_topbar_render = function()
+      return nil
+    end
+
+    topbar.render()
+
+    assert.is_true(vim.wait(1000, function()
+      return vim.api.nvim_get_option_value('winbar', { win = state.windows.output_win }) == '%='
+    end))
+    local rendered = vim.api.nvim_eval_statusline(vim.wo[state.windows.output_win].winbar, {
+      winid = state.windows.output_win,
+      use_winbar = true,
+    })
+    assert.equals('', vim.trim(rendered.str))
+  end)
+
+  it('lets footer hook prepend a left-aligned segment', function()
+    config.hooks.on_footer_render = function(segments)
+      table.insert(segments, 1, { 'repo:branch ', 'OpencodeHint' })
+      return segments
+    end
+
+    footer.render()
+
+    local lines = vim.api.nvim_buf_get_lines(state.windows.footer_buf, 0, -1, false)
+    assert.is_true(lines[1]:find('repo:branch ', 1, true) == 1)
+  end)
+
+  it('clears footer when hook returns nil', function()
+    config.hooks.on_footer_render = function()
+      return nil
+    end
+
+    footer.render()
+
+    local lines = vim.api.nvim_buf_get_lines(state.windows.footer_buf, 0, -1, false)
+    assert.are.same({ '' }, lines)
+  end)
+end)