refactor(git): URI scheme is now a git revspec, loaded via cat-file -p

lua/git/sidebar.lua

@@ -484,15 +484,19 @@ end
 ---@return ow.Git.DiffSide
 local function head_pane(worktree, path)
     return {
-        buf = diff.git_show_buf(worktree, "HEAD", path),
-        name = "git://HEAD//" .. path,
+        buf = diff.git_show_buf(worktree, "HEAD:" .. path),
+        name = "git://HEAD:" .. path,
     }
 end
 
+---@param worktree string
 ---@param path string
 ---@return ow.Git.DiffSide
-local function head_empty_pane(path)
-    return { buf = diff.empty_buf(), name = "git://HEAD//" .. path }
+local function absent_pane(worktree, path)
+    return {
+        buf = diff.empty_buf(),
+        name = "[absent] " .. vim.fs.joinpath(worktree, path),
+    }
 end
 
 ---@param worktree string
@@ -505,12 +509,6 @@ local function worktree_pane(worktree, path)
     }
 end
 
----@param path string
----@return ow.Git.DiffSide
-local function worktree_empty_pane(path)
-    return { buf = diff.empty_buf(), name = "git://worktree//" .. path }
-end
-
 ---@param s ow.Git.SidebarState
 ---@param entry ow.Git.FileEntry
 ---@return ow.Git.DiffSide
@@ -519,10 +517,12 @@ local function index_pane(s, entry)
         entry.section == "Untracked"
         or (entry.section == "Staged" and entry.x == "D")
     )
+    if not in_index then
+        return absent_pane(s.worktree, entry.path)
+    end
     return {
-        buf = in_index and diff.git_show_buf(s.worktree, "index", entry.path)
-            or diff.empty_buf(),
-        name = "git://index//" .. entry.path,
+        buf = diff.git_show_buf(s.worktree, ":" .. entry.path),
+        name = "git://:" .. entry.path,
     }
 end
 
@@ -534,7 +534,7 @@ local function other_pane(s, entry)
     local worktree = s.worktree
     if entry.section == "Staged" then
         if entry.x == "A" then
-            return head_empty_pane(p)
+            return absent_pane(worktree, p)
         end
         if entry.x == "D" then
             return head_pane(worktree, p)
@@ -544,7 +544,7 @@ local function other_pane(s, entry)
     end
     if entry.section == "Unstaged" then
         if entry.y == "D" then
-            return worktree_empty_pane(p)
+            return absent_pane(worktree, p)
         end
         return worktree_pane(worktree, p)
     end