refactor(hooks): replace flat hooks API with setup/on namespaces

Problem: the hooks API conflated distinct lifecycle scopes under a flat
table with inconsistent naming (setup_code, before_run, setup_io_input),
making it hard to reason about when each hook fires.

Solution: introduce two namespaces — hooks.setup.{contest,code,io} for
one-time initialization and hooks.on.{enter,run,debug} for recurring
events. hooks.setup.contest fires once when a contest dir is newly
created; hooks.on.enter is registered as a buffer-scoped BufEnter
autocmd and fires immediately after setup.code. The provisional buffer
setup_code callsite is removed as it ran on an unresolved temp buffer.

lua/cp/config.lua

@@ -33,12 +33,23 @@
 ---@class DiffConfig
 ---@field git DiffGitConfig
 
+---@class CpSetupIOHooks
+---@field input?  fun(bufnr: integer, state: cp.State)
+---@field output? fun(bufnr: integer, state: cp.State)
+
+---@class CpSetupHooks
+---@field contest? fun(state: cp.State)
+---@field code?    fun(state: cp.State)
+---@field io?      CpSetupIOHooks
+
+---@class CpOnHooks
+---@field enter? fun(state: cp.State)
+---@field run?   fun(state: cp.State)
+---@field debug? fun(state: cp.State)
+
 ---@class Hooks
----@field before_run? fun(state: cp.State)
+---@field setup? CpSetupHooks
----@field before_debug? fun(state: cp.State)
+---@field on?    CpOnHooks
----@field setup_code? fun(state: cp.State)
----@field setup_io_input? fun(bufnr: integer, state: cp.State)
----@field setup_io_output? fun(bufnr: integer, state: cp.State)
 
 ---@class VerdictFormatData
 ---@field index integer
@@ -156,11 +167,19 @@ M.defaults = {
     },
   },
   hooks = {
-    before_run = nil,
+    setup = {
-    before_debug = nil,
+      contest = nil,
-    setup_code = nil,
+      code    = nil,
-    setup_io_input = helpers.clearcol,
+      io = {
-    setup_io_output = helpers.clearcol,
+        input  = helpers.clearcol,
+        output = helpers.clearcol,
+      },
+    },
+    on = {
+      enter = nil,
+      run   = nil,
+      debug = nil,
+    },
   },
   debug = false,
   scrapers = constants.PLATFORMS,
@@ -352,12 +371,29 @@ function M.setup(user_config)
       end,
       ('one of {%s}'):format(table.concat(constants.PLATFORMS, ',')),
     },
-    before_run = { cfg.hooks.before_run, { 'function', 'nil' }, true },
-    before_debug = { cfg.hooks.before_debug, { 'function', 'nil' }, true },
-    setup_code = { cfg.hooks.setup_code, { 'function', 'nil' }, true },
-    setup_io_input = { cfg.hooks.setup_io_input, { 'function', 'nil' }, true },
-    setup_io_output = { cfg.hooks.setup_io_output, { 'function', 'nil' }, true },
   })
+  if cfg.hooks.setup ~= nil then
+    vim.validate({ setup = { cfg.hooks.setup, 'table' } })
+    vim.validate({
+      contest = { cfg.hooks.setup.contest, { 'function', 'nil' }, true },
+      code    = { cfg.hooks.setup.code,    { 'function', 'nil' }, true },
+    })
+    if cfg.hooks.setup.io ~= nil then
+      vim.validate({ io = { cfg.hooks.setup.io, 'table' } })
+      vim.validate({
+        input  = { cfg.hooks.setup.io.input,  { 'function', 'nil' }, true },
+        output = { cfg.hooks.setup.io.output, { 'function', 'nil' }, true },
+      })
+    end
+  end
+  if cfg.hooks.on ~= nil then
+    vim.validate({ on = { cfg.hooks.on, 'table' } })
+    vim.validate({
+      enter = { cfg.hooks.on.enter, { 'function', 'nil' }, true },
+      run   = { cfg.hooks.on.run,   { 'function', 'nil' }, true },
+      debug = { cfg.hooks.on.debug, { 'function', 'nil' }, true },
+    })
+  end
 
   local layouts = require('cp.ui.layouts')
   vim.validate({

lua/cp/setup.lua

@@ -196,13 +196,6 @@ function M.setup_contest(platform, contest_id, problem_id, language)
 
     state.set_language(lang)
 
-    if cfg.hooks and cfg.hooks.setup_code and not vim.b[bufnr].cp_setup_done then
-      local ok = pcall(cfg.hooks.setup_code, state)
-      if ok then
-        vim.b[bufnr].cp_setup_done = true
-      end
-    end
-
     state.set_provisional({
       bufnr = bufnr,
       platform = platform,
@@ -281,7 +274,15 @@ function M.setup_problem(problem_id, language)
     return
   end
 
-  vim.fn.mkdir(vim.fn.fnamemodify(source_file, ':h'), 'p')
+  local contest_dir = vim.fn.fnamemodify(source_file, ':h')
+  local is_new_dir = vim.fn.isdirectory(contest_dir) == 0
+  vim.fn.mkdir(contest_dir, 'p')
+  if is_new_dir then
+    local s = config.hooks and config.hooks.setup
+    if s and s.contest then
+      pcall(s.contest, state)
+    end
+  end
 
   local prov = state.get_provisional()
   if prov and prov.platform == platform and prov.contest_id == (state.get_contest_id() or '') then
@@ -302,15 +303,23 @@ function M.setup_problem(problem_id, language)
         state.set_solution_win(vim.api.nvim_get_current_win())
         if not vim.b[prov.bufnr].cp_setup_done then
           apply_template(prov.bufnr, lang, platform)
-          if config.hooks and config.hooks.setup_code then
+          local s = config.hooks and config.hooks.setup
-            local ok = pcall(config.hooks.setup_code, state)
+          if s and s.code then
-            if ok then
+            local ok = pcall(s.code, state)
-              vim.b[prov.bufnr].cp_setup_done = true
+            if ok then vim.b[prov.bufnr].cp_setup_done = true end
-            end
           else
             helpers.clearcol(prov.bufnr)
             vim.b[prov.bufnr].cp_setup_done = true
           end
+          local o = config.hooks and config.hooks.on
+          if o and o.enter then
+            local bufnr = prov.bufnr
+            vim.api.nvim_create_autocmd('BufEnter', {
+              buffer = bufnr,
+              callback = function() pcall(o.enter, state) end,
+            })
+            pcall(o.enter, state)
+          end
         end
         cache.set_file_state(
           vim.fn.fnamemodify(source_file, ':p'),
@@ -339,15 +348,22 @@ function M.setup_problem(problem_id, language)
     if is_new then
       apply_template(bufnr, lang, platform)
     end
-    if config.hooks and config.hooks.setup_code then
+    local s = config.hooks and config.hooks.setup
-      local ok = pcall(config.hooks.setup_code, state)
+    if s and s.code then
-      if ok then
+      local ok = pcall(s.code, state)
-        vim.b[bufnr].cp_setup_done = true
+      if ok then vim.b[bufnr].cp_setup_done = true end
-      end
     else
       helpers.clearcol(bufnr)
       vim.b[bufnr].cp_setup_done = true
     end
+    local o = config.hooks and config.hooks.on
+    if o and o.enter then
+      vim.api.nvim_create_autocmd('BufEnter', {
+        buffer = bufnr,
+        callback = function() pcall(o.enter, state) end,
+      })
+      pcall(o.enter, state)
+    end
   end
   cache.set_file_state(
     vim.fn.expand('%:p'),

lua/cp/ui/views.lua

@@ -444,12 +444,12 @@ function M.ensure_io_view()
 
   local cfg = config_module.get_config()
 
-  if cfg.hooks and cfg.hooks.setup_io_output then
+  local io = cfg.hooks and cfg.hooks.setup and cfg.hooks.setup.io
-    pcall(cfg.hooks.setup_io_output, output_buf, state)
+  if io and io.output then
+    pcall(io.output, output_buf, state)
   end
-
+  if io and io.input then
-  if cfg.hooks and cfg.hooks.setup_io_input then
+    pcall(io.input, input_buf, state)
-    pcall(cfg.hooks.setup_io_input, input_buf, state)
   end
 
   local test_cases = cache.get_test_cases(platform, contest_id, problem_id)
@@ -958,15 +958,12 @@ function M.toggle_panel(panel_opts)
 
   setup_keybindings_for_buffer(test_buffers.tab_buf)
 
-  if config.hooks and config.hooks.before_run then
+  local o = config.hooks and config.hooks.on
-    vim.schedule_wrap(function()
+  if o and o.run then
-      config.hooks.before_run(state)
+    vim.schedule(function() o.run(state) end)
-    end)
   end
-  if panel_opts and panel_opts.debug and config.hooks and config.hooks.before_debug then
+  if panel_opts and panel_opts.debug and o and o.debug then
-    vim.schedule_wrap(function()
+    vim.schedule(function() o.debug(state) end)
-      config.hooks.before_debug(state)
-    end)
   end
 
   vim.api.nvim_set_current_win(test_windows.tab_win)