fix: support git worktree by using --git-common-dir for storage path

lua/tabi/storage/local.lua

@@ -4,13 +4,14 @@ local M = {}
 local utils = require("tabi.utils")
 
 --- Get storage directory path
+--- Uses git common directory to support git worktrees, where .git is a file rather than a directory.
 ---@return string|nil
 function M.get_storage_dir()
-  local git_root = utils.get_git_root()
-  if not git_root then
+  local git_common_dir = utils.get_git_common_dir()
+  if not git_common_dir then
     return nil
   end
-  return git_root .. "/.git/tabi"
+  return git_common_dir .. "/tabi"
 end
 
 --- Get sessions directory path

lua/tabi/utils.lua

@@ -53,6 +53,29 @@ function M.get_git_root()
   return root and vim.trim(root) or nil
 end
 
+--- Get git common directory (resolves git worktree gitfiles to the actual .git directory)
+--- In a normal repo, returns the same as .git directory.
+--- In a worktree, returns the main repository's .git directory instead of the worktree-specific one.
+---@return string|nil
+function M.get_git_common_dir()
+  local handle = io.popen("git rev-parse --git-common-dir 2>/dev/null")
+  if not handle then
+    return nil
+  end
+  local dir = handle:read("*a")
+  handle:close()
+  if not dir or vim.trim(dir) == "" then
+    return nil
+  end
+  dir = vim.trim(dir)
+  -- --git-common-dir may return a relative path; convert to absolute
+  if not vim.startswith(dir, "/") then
+    local cwd = vim.fn.getcwd()
+    dir = cwd .. "/" .. dir
+  end
+  return dir
+end
+
 --- Ensure directory exists
 ---@param path string
 function M.ensure_dir(path)

test/tabi/storage/local_spec.lua

@@ -3,20 +3,20 @@ local utils = require("tabi.utils")
 
 describe("tabi.storage.local", function()
   local temp_dir
-  local original_get_git_root
+  local original_get_git_common_dir
   local original_is_git_repo
 
   before_each(function()
-    -- Create temporary directory to simulate git repo
+    -- Create temporary directory to simulate git repo's .git directory
     temp_dir = vim.fn.tempname() .. "_tabi_local_test"
     vim.fn.mkdir(temp_dir .. "/.git", "p")
 
     -- Mock git functions
-    original_get_git_root = utils.get_git_root
+    original_get_git_common_dir = utils.get_git_common_dir
     original_is_git_repo = utils.is_git_repo
 
-    utils.get_git_root = function()
-      return temp_dir
+    utils.get_git_common_dir = function()
+      return temp_dir .. "/.git"
     end
 
     utils.is_git_repo = function()
@@ -26,7 +26,7 @@ describe("tabi.storage.local", function()
 
   after_each(function()
     -- Restore original functions
-    utils.get_git_root = original_get_git_root
+    utils.get_git_common_dir = original_get_git_common_dir
     utils.is_git_repo = original_is_git_repo
 
     -- Clean up temporary directory
@@ -42,12 +42,26 @@ describe("tabi.storage.local", function()
     end)
 
     it("should return nil when not in git repo", function()
-      utils.get_git_root = function()
+      utils.get_git_common_dir = function()
         return nil
       end
       local dir = local_storage.get_storage_dir()
       assert.is_nil(dir)
     end)
+
+    it("should use the common git dir so worktrees share storage", function()
+      -- Simulate a worktree: git_common_dir points to the main repo's .git
+      local main_git_dir = vim.fn.tempname() .. "_main_git"
+      vim.fn.mkdir(main_git_dir, "p")
+      utils.get_git_common_dir = function()
+        return main_git_dir
+      end
+
+      local dir = local_storage.get_storage_dir()
+      assert.are.equal(main_git_dir .. "/tabi", dir)
+
+      vim.fn.delete(main_git_dir, "rf")
+    end)
   end)
 
   describe("get_sessions_dir", function()
@@ -57,7 +71,7 @@ describe("tabi.storage.local", function()
     end)
 
     it("should return nil when not in git repo", function()
-      utils.get_git_root = function()
+      utils.get_git_common_dir = function()
         return nil
       end
       local dir = local_storage.get_sessions_dir()

test/tabi/utils_spec.lua

@@ -64,6 +64,20 @@ describe("tabi.utils", function()
     end)
   end)
 
+  describe("get_git_common_dir", function()
+    it("should return a non-empty string when in a git repo", function()
+      -- This test runs inside the tabi.nvim git repo
+      local dir = utils.get_git_common_dir()
+      -- May be nil in environments without git, so only assert format when non-nil
+      if dir ~= nil then
+        assert.is_string(dir)
+        assert.is_true(#dir > 0)
+        -- Must be an absolute path
+        assert.is_true(vim.startswith(dir, "/"), "get_git_common_dir should return an absolute path, got: " .. dir)
+      end
+    end)
+  end)
+
   describe("ensure_dir", function()
     local temp_dir