refactor(git): give URI buffer refresh a content-only path

lua/git/object.lua

@@ -164,36 +164,19 @@ function M.buf_for(r, rev)
 end
 
 ---@param buf integer
-function M.read_uri(buf)
-    local name = vim.api.nvim_buf_get_name(buf)
-    local rev = M.parse_uri(name)
-    if not rev then
-        return
-    end
+---@param r ow.Git.Repo
+---@param rev ow.Git.Revision
+---@param state ow.Git.Repo.BufState
+---@param rev_sha string
+---@return boolean ok
+local function populate(buf, r, rev, state, rev_sha)
     local rev_str = rev:format()
-
-    local r = repo.resolve(buf)
-    if not r then
-        util.error("git BufReadCmd %s: cannot resolve worktree", name)
-        return
-    end
-    repo.bind(buf, r)
-    local state = r:state(buf) --[[@as -nil]]
-
-    vim.bo[buf].swapfile = false
-    vim.bo[buf].bufhidden = "hide"
-
-    local rev_sha = r:rev_parse(rev_str, true)
-    if not rev_sha then
-        return
-    end
-
     local stdout = util.exec(
         { "git", "cat-file", "-p", rev_str },
         { cwd = r.worktree }
     )
     if not stdout then
-        return
+        return false
     end
 
     if rev.path == nil then
@@ -216,10 +199,43 @@ function M.read_uri(buf)
         end
     end
 
+    local was_modifiable = vim.bo[buf].modifiable
     vim.bo[buf].modifiable = true
     vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
-
+    vim.bo[buf].modifiable = was_modifiable
+    vim.bo[buf].modified = false
     state.sha = rev_sha
+    return true
+end
+
+---@param buf integer
+function M.read_uri(buf)
+    local name = vim.api.nvim_buf_get_name(buf)
+    local rev = M.parse_uri(name)
+    if not rev then
+        return
+    end
+
+    local r = repo.resolve(buf)
+    if not r then
+        util.error("git BufReadCmd %s: cannot resolve worktree", name)
+        return
+    end
+    repo.bind(buf, r)
+    local state = r:state(buf) --[[@as -nil]]
+
+    vim.bo[buf].swapfile = false
+    vim.bo[buf].bufhidden = "hide"
+
+    local rev_sha = r:rev_parse(rev:format(), true)
+    if not rev_sha then
+        return
+    end
+
+    if not populate(buf, r, rev, state, rev_sha) then
+        return
+    end
+
     state.immutable = is_immutable_rev(rev)
 
     if rev.stage == 0 and rev.path then
@@ -232,7 +248,6 @@ function M.read_uri(buf)
         vim.bo[buf].buftype = "nofile"
         vim.bo[buf].modifiable = false
     end
-    vim.bo[buf].modified = false
 
     if rev.path then
         local ft = vim.filetype.match({ filename = rev.path, buf = buf })
@@ -265,7 +280,7 @@ local function refresh(buf, r)
     if not rev_sha or rev_sha == state.sha then
         return
     end
-    M.read_uri(buf)
+    populate(buf, r, rev, state, rev_sha)
 end
 
 ---@param r ow.Git.Repo