refactor(git): load git:// URI buffers via BufReadCmd

lua/git/show.lua

@@ -80,30 +80,19 @@ local function is_zero(sha)
     return sha == nil or sha:match("^0+$") ~= nil
 end
 
----Build a buffer holding the file's content at a given blob, named after the
----commit ref it corresponds to (so the name lines up with `git log` output
----instead of an opaque blob hash).
+---Buffer for the file at `<ref>:<path>`. A zero/nil blob (file absent on
+---this side of the diff) yields an empty placeholder.
 ---@param worktree string
 ---@param blob string?
 ---@param path string
 ---@param ref string  the commit ref the blob represents (e.g. `<sha>` or `<sha>^`)
 ---@return integer
 local function blob_buf(worktree, blob, path, ref)
-    local name = "git://" .. ref .. "/" .. path
-    -- Reuse an existing buffer with this name (commit refs and blobs are
-    -- immutable, so the content is stable); avoids E95 collisions and
-    -- prevents accumulating duplicate buffers as the user navigates.
-    local existing = vim.fn.bufnr(name)
-    if existing ~= -1 and vim.api.nvim_buf_is_loaded(existing) then
-        return existing
-    end
+    local name = "git://" .. ref .. "//" .. path
     if is_zero(blob) then
         return diff.empty_buf({ name = name, bufhidden = "hide" })
     end
-    ---@cast blob string
-    local buf = diff.git_show_blob(worktree, blob)
-    diff.set_buf_name_and_filetype(buf, name)
-    return buf
+    return diff.git_show_buf(worktree, ref, path)
 end
 
 ---@param worktree string
@@ -143,7 +132,7 @@ end
 function M.open_commit(worktree, ref)
     repo.rev_parse(worktree, ref, true, function(resolved)
         local sha = resolved or ref
-        local name = "git://" .. sha .. "/"
+        local name = "git://" .. sha .. "//"
         -- Reuse a previously-opened buffer for the same commit; commit SHAs
         -- are immutable so the content is stable.
         local existing = vim.fn.bufnr(name)