feat(gitcommit): add commit history context for message generation

- introduce `use_commit_history` and `commit_history_count` options to include recent commit messages as context
- update generator to pass commit history to LLM prompt for improved style consistency
- implement `Git.get_commit_history` to retrieve recent commit messages from git log
- update configuration, types, and example config to support and document the new feature
- ensure commit history context is used across buffer, init, and generator modules

Author: jinzhongjia

config_example_with_history.lua

@@ -0,0 +1,58 @@
+-- Example configuration showing how to use the new commit history feature
+
+require("codecompanion").setup({
+  adapters = {
+    openai = function()
+      return require("codecompanion.adapters").use("openai", {
+        env = {
+          api_key = "your_api_key_here"
+        },
+      })
+    end,
+  },
+  extensions = {
+    -- GitCommit extension with history context enabled
+    require("codecompanion._extensions.gitcommit").setup({
+      -- Core configuration
+      adapter = "openai",
+      model = "gpt-4-turbo-preview",
+      languages = { "English", "Chinese" },
+      
+      -- NEW: History commit context configuration
+      use_commit_history = true,        -- Enable using commit history as context
+      commit_history_count = 15,        -- Use 15 recent commits for context (default: 10)
+      
+      -- Existing configuration options
+      buffer = {
+        enabled = true,
+        keymap = "<leader>gc",
+        auto_generate = true,
+        auto_generate_delay = 200,
+        skip_auto_generate_on_amend = true,
+      },
+      
+      exclude_files = {
+        "*.pb.go",
+        "*.min.js",
+        "package-lock.json",
+        "yarn.lock",
+        "*.log",
+        "dist/*",
+        "build/*",
+        "node_modules/*",
+      },
+      
+      add_git_tool = true,
+      enable_git_read = true,
+      enable_git_edit = true,
+      enable_git_bot = true,
+      git_tool_auto_submit_success = true,
+    })
+  },
+})
+
+-- Alternative configuration with history disabled
+-- require("codecompanion._extensions.gitcommit").setup({
+--   use_commit_history = false,  -- Disable history context
+--   -- ... other options
+-- })

lua/codecompanion/_extensions/gitcommit/buffer.lua

@@ -114,8 +114,16 @@ function Buffer._generate_and_insert_commit_message(bufnr)
 
   Langs.select_lang(function(lang)
     vim.notify("Generating commit message...", vim.log.levels.INFO)
+    
+    -- Get commit history if enabled
+    local commit_history = nil
+    local git_config = Git.get_config and Git.get_config() or {}
+    if git_config.use_commit_history then
+      commit_history = Git.get_commit_history(git_config.commit_history_count)
+    end
+    
     -- Generate commit message using LLM
-    Generator.generate_commit_message(diff, lang, function(result, error)
+    Generator.generate_commit_message(diff, lang, commit_history, function(result, error)
       if error then
         vim.notify("Failed to generate commit message: " .. error, vim.log.levels.ERROR)
         return

lua/codecompanion/_extensions/gitcommit/config.lua

@@ -34,6 +34,9 @@ M.default_opts = {
   git_tool_auto_submit_errors = false,
   git_tool_auto_submit_success = true,
   gitcommit_select_count = 100,
+  -- History commit context configuration
+  use_commit_history = true, -- Enable using commit history as context
+  commit_history_count = 10, -- Number of recent commits to include as context
 }
 
 return M

lua/codecompanion/_extensions/gitcommit/generator.lua

@@ -27,13 +27,8 @@ function Generator.setup(adapter, model)
     error("Invalid adapter specified: " .. tostring(_adapter))
   end
 end
-
----Generate commit message using LLM
----
----@param diff string The git diff to analyze
----@param lang? string The language to generate the commit message in (optional)
----@param callback fun(result: string|nil, error: string|nil) Callback function
-function Generator.generate_commit_message(diff, lang, callback)
+---@param commit_history? string[] Array of recent commit messages for context (optional)
+function Generator.generate_commit_message(diff, lang, commit_history, callback)
   -- Setup adapter
   local adapter = codecompanion_adapter.resolve(_adapter)
   if not adapter then
@@ -49,7 +44,7 @@ function Generator.generate_commit_message(diff, lang, callback)
   })
 
   -- Create prompt for LLM
-  local prompt = Generator._create_prompt(diff, lang)
+  local prompt = Generator._create_prompt(diff, lang, commit_history)
 
   local payload = {
     messages = adapter:map_roles({
@@ -69,11 +64,20 @@ end
 
 ---Create prompt for commit message generation
 ---@param diff string The git diff to include in prompt
----@param lang? string The generate language (optional, not used in this implementation)
----@return string prompt The formatted prompt
-function Generator._create_prompt(diff, lang)
+ ---@param commit_history? string[] Array of recent commit messages for context (optional)
+ function Generator._create_prompt(diff, lang, commit_history)
+   -- Build the history context section
+   local history_context = ""
+   if commit_history and #commit_history > 0 then
+     history_context = "\nRECENT COMMIT HISTORY (for style reference):\n"
+     for i, commit_msg in ipairs(commit_history) do
+       history_context = history_context .. string.format("%d. %s\n", i, commit_msg)
+     end
+     history_context = history_context .. "\nAnalyze the above commit history to understand the project's commit style, tone, and format patterns. Use this as guidance to maintain consistency.\n"
+   end
+ 
   return string.format(
-    [[You are a commit message generator. Generate exactly ONE complete Conventional Commit message for the provided git diff.
+    [[You are a commit message generator. Generate exactly ONE complete Conventional Commit message for the provided git diff.%s
 
 CRITICAL FORMAT REQUIREMENTS:
 1. MUST generate exactly ONE commit message, never multiple messages
@@ -95,8 +99,7 @@ RULES:
 - Title: Use imperative mood ("add" not "added"), keep under 50 characters
 - Body: At least ONE bullet point describing the changes
 - For large diffs: Focus on the most significant changes, group related changes
-- Choose the primary type that best represents the overall change
-- Even with extensive changes, generate only ONE unified commit message
+ - If commit history is provided, follow the established patterns and style from recent commits
 
 REQUIRED EXAMPLES:
 feat(auth): add OAuth2 integration
@@ -116,6 +119,7 @@ Generate ONE complete commit message for this diff:
 ```
 
 Return ONLY the commit message in the exact format shown above.]],
+    history_context,
     lang or "English",
     diff
   )

lua/codecompanion/_extensions/gitcommit/git.lua

@@ -4,11 +4,11 @@ local Git = {}
 -- Store configuration
 local config = {}
 
----Setup Git module with configuration
----@param opts? table Configuration options
 function Git.setup(opts)
   config = vim.tbl_deep_extend("force", {
     exclude_files = {},
+    use_commit_history = true,
+    commit_history_count = 10,
   }, opts or {})
 end
 
@@ -342,4 +342,52 @@ function Git.commit_changes(message)
   return success
 end
 
+---Get recent commit messages for context
+---@param count? number Number of recent commits to retrieve (default: 10)
+---@return string[]|nil commit_messages Array of commit messages or nil on error
+function Git.get_commit_history(count)
+  count = count or 10
+  
+  -- Use pcall to safely execute git operations
+  local ok, result = pcall(function()
+    if not Git.is_repository() then
+      return nil
+    end
+
+    -- Get recent commit messages using git log
+    -- Use --pretty=format to get just the commit message
+    local cmd = string.format("git log --pretty=format:%%s --no-merges -%d", count)
+    local output = vim.fn.system(cmd)
+    
+    if vim.v.shell_error ~= 0 then
+      return nil
+    end
+
+    -- Split output into lines and filter out empty lines
+    local lines = vim.split(output, "\n")
+    local commit_messages = {}
+    
+    for _, line in ipairs(lines) do
+      local trimmed = trim(line)
+      if trimmed ~= "" then
+        table.insert(commit_messages, trimmed)
+      end
+    end
+    
+    return commit_messages
+  end)
+
+  if not ok then
+    return nil
+  end
+
+  return result
+end
+
+---Get current configuration
+---@return table config Current configuration
+function Git.get_config()
+  return vim.deepcopy(config)
+end
+
 return Git

lua/codecompanion/_extensions/gitcommit/init.lua

@@ -32,8 +32,16 @@ function M.generate_commit_message()
 
   Langs.select_lang(function(lang)
     vim.notify("Generating commit message...", vim.log.levels.INFO)
+    
+    -- Get commit history if enabled
+    local commit_history = nil
+    local git_config = Git.get_config and Git.get_config() or {}
+    if git_config.use_commit_history then
+      commit_history = Git.get_commit_history(git_config.commit_history_count)
+    end
+    
     -- Generate commit message using LLM
-    Generator.generate_commit_message(diff, lang, function(result, error)
+    Generator.generate_commit_message(diff, lang, commit_history, function(result, error)
       if error then
         vim.notify("Failed to generate commit message: " .. error, vim.log.levels.ERROR)
         return
@@ -268,7 +276,11 @@ return {
   setup = function(opts)
     opts = vim.tbl_deep_extend("force", Config.default_opts, opts or {})
 
-    Git.setup({ exclude_files = opts.exclude_files })
+    Git.setup({ 
+      exclude_files = opts.exclude_files,
+      use_commit_history = opts.use_commit_history,
+      commit_history_count = opts.commit_history_count,
+    })
     Generator.setup(opts.adapter, opts.model)
     Buffer.setup(opts.buffer)
     Langs.setup(opts.languages)
@@ -294,8 +306,15 @@ return {
         return callback(nil, "No staged changes found. Please stage your changes first.")
       end
 
+      -- Get commit history if enabled
+      local commit_history = nil
+      local git_config = Git.get_config and Git.get_config() or {}
+      if git_config.use_commit_history then
+        commit_history = Git.get_commit_history(git_config.commit_history_count)
+      end
+
       -- Generate commit message
-      Generator.generate_commit_message(diff, lang, callback)
+      Generator.generate_commit_message(diff, lang, commit_history, callback)
     end,
 
     ---Check if current directory is in a git repository

lua/codecompanion/_extensions/gitcommit/types.lua

@@ -1,7 +1,6 @@
----@meta
+---@field use_commit_history? boolean Enable using commit history as context (default: true)
+---@field commit_history_count? number Number of recent commits to include as context (default: 10)
 
----@class CodeCompanion.GitCommit.Extension
----@field setup fun(opts: CodeCompanion.GitCommit.ExtensionOpts): nil
 ---@field exports CodeCompanion.GitCommit.Exports
 
 ---@class CodeCompanion.GitCommit.ExtensionOpts.Buffer
@@ -54,8 +53,7 @@
 ---@field get_staged_diff fun(): string|nil -- Get git diff for staged changes
 ---@field commit_changes fun(message: string): boolean -- Commit changes with the provided message
 
----@class CodeCompanion.GitCommit.Generator
----@field generate_commit_message fun(diff: string,lang: string?, callback: fun(result: string|nil, error: string|nil)): nil -- Generate commit message using LLM
+ ---@field generate_commit_message fun(diff: string,lang: string?, commit_history: string[]?, callback: fun(result: string|nil, error: string|nil)): nil -- Generate commit message using LLM
 
 ---@class CodeCompanion.GitCommit.UI
 ---@field show_commit_message fun(message: string, on_commit: fun(message: string): boolean): nil -- Show commit message in a floating window with interactive options