feat(views): add hide_done_categories config option (#153)

Problem: Categories where every task is done still render in the buffer,
cluttering the view when entire categories are finished.

Solution: Add `view.category.hide_done_categories` (boolean, default
false). When enabled, `category_view()` skips categories whose tasks are
all done/deleted, returns their IDs as `done_cat_hidden_ids`, and
`_on_write` merges those IDs into `hidden_ids` passed to `diff.apply()`
so hidden tasks are not mistakenly deleted on `:w`.

doc/pending.txt

@@ -879,6 +879,16 @@ Fields: ~
                                           `false` uses Vim's built-in foldtext.
                                       Folds only apply to category view.
 
+                           {hide_done_categories}
+                                      (boolean, default: false)
+                                      When true, categories where every task is
+                                      done (or deleted) are hidden from the
+                                      rendered buffer. The tasks remain in the
+                                      store and reappear when any task in the
+                                      category is un-done or a new pending task
+                                      is added. Hidden tasks are protected from
+                                      deletion on `:w`.
+
                          {queue}     (table)            *pending.QueueViewConfig*
                                     Queue (priority) view settings.
 

lua/pending/buffer.lua

@@ -27,6 +27,8 @@ local _filter_predicates = {}
 ---@type table<integer, true>
 local _hidden_ids = {}
 ---@type table<integer, true>
+local _done_cat_hidden_ids = {}
+---@type table<integer, true>
 local _dirty_rows = {}
 ---@type boolean
 local _on_bytes_active = false
@@ -74,6 +76,11 @@ function M.hidden_ids()
   return _hidden_ids
 end
 
+---@return table<integer, true>
+function M.done_cat_hidden_ids()
+  return _done_cat_hidden_ids
+end
+
 ---@param predicates string[]
 ---@param hidden table<integer, true>
 ---@return nil
@@ -694,10 +701,13 @@ function M.render(bufnr)
   end
 
   local lines, line_meta
+  _done_cat_hidden_ids = {}
   if current_view == 'priority' then
     lines, line_meta = views.priority_view(tasks)
   else
-    lines, line_meta = views.category_view(tasks)
+    local done_cat_hidden
+    lines, line_meta, done_cat_hidden = views.category_view(tasks)
+    _done_cat_hidden_ids = done_cat_hidden
   end
 
   if #lines == 0 and #_filter_predicates == 0 then

lua/pending/config.lua

@@ -84,6 +84,7 @@
 ---@class pending.CategoryViewConfig
 ---@field order? string[]
 ---@field folding? boolean|pending.FoldingConfig
+---@field hide_done_categories? boolean
 
 ---@class pending.QueueViewConfig
 
@@ -130,6 +131,7 @@ local defaults = {
     category = {
       order = {},
       folding = true,
+      hide_done_categories = false,
     },
     queue = {},
   },

lua/pending/init.lua

@@ -509,6 +509,9 @@ function M._on_write(bufnr)
   if #stack > UNDO_MAX then
     table.remove(stack, 1)
   end
+  for id in pairs(buffer.done_cat_hidden_ids()) do
+    hidden[id] = true
+  end
   local new_refs = diff.apply(lines, s, hidden)
   M._recompute_counts()
   buffer.render(bufnr)

lua/pending/views.lua

@@ -138,6 +138,7 @@ end
 ---@param tasks pending.Task[]
 ---@return string[] lines
 ---@return pending.LineMeta[] meta
+---@return table<integer, true> done_cat_hidden_ids
 function M.category_view(tasks)
   local by_cat = {}
   local cat_order = {}
@@ -177,6 +178,9 @@ function M.category_view(tasks)
     cat_order = ordered
   end
 
+  local hide_done = config.get().view.category.hide_done_categories
+  local done_cat_hidden = {} ---@type table<integer, true>
+
   for _, cat in ipairs(cat_order) do
     sort_tasks(by_cat[cat])
     sort_tasks(done_by_cat[cat])
@@ -184,12 +188,21 @@ function M.category_view(tasks)
 
   local lines = {}
   local meta = {}
+  local rendered = 0
 
-  for i, cat in ipairs(cat_order) do
-    if i > 1 then
+  for _, cat in ipairs(cat_order) do
+    if hide_done and #by_cat[cat] == 0 and #done_by_cat[cat] > 0 then
+      for _, t in ipairs(done_by_cat[cat]) do
+        done_cat_hidden[t.id] = true
+      end
+      goto next_cat
+    end
+
+    if rendered > 0 then
       table.insert(lines, '')
       table.insert(meta, { type = 'blank' })
     end
+    rendered = rendered + 1
     table.insert(lines, '# ' .. cat)
     table.insert(meta, { type = 'header', category = cat })
 
@@ -220,9 +233,11 @@ function M.category_view(tasks)
         forge_spans = compute_forge_spans(task, prefix_len),
       })
     end
+
+    ::next_cat::
   end
 
-  return lines, meta
+  return lines, meta, done_cat_hidden
 end
 
 ---@param tasks pending.Task[]

spec/views_spec.lua

@@ -280,6 +280,85 @@ describe('views', function()
       assert.are.equal('# Alpha', headers[1])
       assert.are.equal('# Beta', headers[2])
     end)
+
+    it('returns empty done_cat_hidden_ids when hide_done_categories is false', function()
+      local t1 = s:add({ description = 'Done task', category = 'Work' })
+      s:update(t1.id, { status = 'done' })
+      s:add({ description = 'Active', category = 'Personal' })
+      local _, _, done_hidden = views.category_view(s:active_tasks())
+      assert.are.same({}, done_hidden)
+    end)
+
+    it('hides categories with only done tasks when hide_done_categories is true', function()
+      vim.g.pending = {
+        data_path = tmpdir .. '/tasks.json',
+        view = { category = { hide_done_categories = true } },
+      }
+      config.reset()
+      local t1 = s:add({ description = 'Done task', category = 'Work' })
+      s:update(t1.id, { status = 'done' })
+      s:add({ description = 'Active', category = 'Personal' })
+      local lines, meta, done_hidden = views.category_view(s:active_tasks())
+      local headers = {}
+      for i, m in ipairs(meta) do
+        if m.type == 'header' then
+          table.insert(headers, lines[i])
+        end
+      end
+      assert.are.equal(1, #headers)
+      assert.are.equal('# Personal', headers[1])
+      assert.are.same({ [t1.id] = true }, done_hidden)
+    end)
+
+    it('shows categories with a mix of done and pending tasks', function()
+      vim.g.pending = {
+        data_path = tmpdir .. '/tasks.json',
+        view = { category = { hide_done_categories = true } },
+      }
+      config.reset()
+      local t1 = s:add({ description = 'Done task', category = 'Work' })
+      s:update(t1.id, { status = 'done' })
+      s:add({ description = 'Active task', category = 'Work' })
+      local lines, meta, done_hidden = views.category_view(s:active_tasks())
+      local headers = {}
+      for i, m in ipairs(meta) do
+        if m.type == 'header' then
+          table.insert(headers, lines[i])
+        end
+      end
+      assert.are.equal(1, #headers)
+      assert.are.equal('# Work', headers[1])
+      assert.are.same({}, done_hidden)
+    end)
+
+    it('does not insert leading blank line when first category is hidden', function()
+      vim.g.pending = {
+        data_path = tmpdir .. '/tasks.json',
+        view = { category = { hide_done_categories = true } },
+      }
+      config.reset()
+      local t1 = s:add({ description = 'Done task', category = 'Alpha' })
+      s:update(t1.id, { status = 'done' })
+      s:add({ description = 'Active', category = 'Beta' })
+      local lines, meta = views.category_view(s:active_tasks())
+      assert.are.equal('header', meta[1].type)
+      assert.are.equal('# Beta', lines[1])
+    end)
+
+    it('returns all done task ids from hidden categories', function()
+      vim.g.pending = {
+        data_path = tmpdir .. '/tasks.json',
+        view = { category = { hide_done_categories = true } },
+      }
+      config.reset()
+      local t1 = s:add({ description = 'Done A', category = 'Work' })
+      local t2 = s:add({ description = 'Done B', category = 'Work' })
+      s:update(t1.id, { status = 'done' })
+      s:update(t2.id, { status = 'done' })
+      s:add({ description = 'Active', category = 'Personal' })
+      local _, _, done_hidden = views.category_view(s:active_tasks())
+      assert.are.same({ [t1.id] = true, [t2.id] = true }, done_hidden)
+    end)
   end)
 
   describe('priority_view', function()