refactor(git): consolidate sync subprocess pattern via util.system_sync

lua/git/diff.lua

@@ -15,24 +15,23 @@ local function attach_index_writer(buf, worktree, path)
                 vim.api.nvim_buf_get_lines(buf, 0, -1, false),
                 "\n"
             ) .. "\n"
-            local hash = vim.system(
+            local hash_stdout = util.system_sync(
                 { "git", "hash-object", "-w", "--stdin" },
-                { cwd = worktree, stdin = body, text = true }
-            ):wait()
-            if hash.code ~= 0 then
-                log.error("git hash-object failed: %s", hash.stderr or "")
+                { cwd = worktree, stdin = body }
+            )
+            if not hash_stdout then
                 return
             end
-            local sha = vim.trim(hash.stdout or "")
+            local sha = vim.trim(hash_stdout)
             local mode = vim.b[buf].git_index_mode
             if not mode then
                 mode = "100644"
-                local ls = vim.system(
+                local ls = util.system_sync(
                     { "git", "ls-files", "-s", "--", path },
-                    { cwd = worktree, text = true }
-                ):wait()
-                if ls.code == 0 and ls.stdout then
-                    local m = ls.stdout:match("^(%d+)")
+                    { cwd = worktree, silent = true }
+                )
+                if ls then
+                    local m = ls:match("^(%d+)")
                     if m then
                         mode = m
                     end
@@ -42,16 +41,16 @@ local function attach_index_writer(buf, worktree, path)
             -- Use the 3-arg form (mode sha path) instead of the comma form
             -- (mode,sha,path), which doesn't survive paths containing a
             -- comma.
-            local upd = vim.system({
+            if
+                not util.system_sync({
                     "git",
                     "update-index",
                     "--cacheinfo",
                     mode,
                     sha,
                     path,
-            }, { cwd = worktree, text = true }):wait()
-            if upd.code ~= 0 then
-                log.error("git update-index failed: %s", upd.stderr or "")
+                }, { cwd = worktree })
+            then
                 return
             end
             vim.bo[buf].modified = false
@@ -105,25 +104,12 @@ function M.read_uri(buf)
     end
 
     local revspec = ref == "index" and (":" .. path) or (ref .. ":" .. path)
-    local result = vim.system(
+    local stdout = util.system_sync(
         { "git", "show", revspec },
-        { cwd = worktree, text = true }
-    )
-        :wait()
-    if result.code == 0 then
-        vim.api.nvim_buf_set_lines(
-            buf,
-            0,
-            -1,
-            false,
-            util.split_lines(result.stdout or "")
-        )
-    else
-        log.error(
-            "git show %s failed: %s",
-            revspec,
-            vim.trim(result.stderr or "")
+        { cwd = worktree }
     )
+    if stdout then
+        vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
     end
 
     if ref == "index" then

lua/git/log.lua

@@ -38,22 +38,15 @@ function M.show(opts)
         table.insert(cmd, "--max-count=" .. max_count)
     end
 
-    local result = vim.system(cmd, { cwd = worktree, text = true }):wait()
-    if result.code ~= 0 then
-        log.error("git log failed: %s", vim.trim(result.stderr or ""))
+    local stdout = util.system_sync(cmd, { cwd = worktree })
+    if not stdout then
         return
     end
 
     local buf = git.new_scratch()
     vim.b[buf].git_worktree = worktree
     vim.bo[buf].modifiable = true
-    vim.api.nvim_buf_set_lines(
-        buf,
-        0,
-        -1,
-        false,
-        util.split_lines(result.stdout or "")
-    )
+    vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
     vim.bo[buf].modifiable = false
     vim.bo[buf].modified = false
     vim.bo[buf].filetype = "gitlog"

lua/git/repo.lua

@@ -336,11 +336,8 @@ function M.rev_parse(worktree, ref, short)
         table.insert(cmd, "--short")
     end
     table.insert(cmd, ref)
-    local result = vim.system(cmd, { cwd = worktree, text = true }):wait()
-    if result.code ~= 0 then
-        return nil
-    end
-    local trimmed = vim.trim(result.stdout or "")
+    local stdout = util.system_sync(cmd, { cwd = worktree, silent = true })
+    local trimmed = stdout and vim.trim(stdout) or ""
     return trimmed ~= "" and trimmed or nil
 end
 

lua/git/show.lua

@@ -152,13 +152,8 @@ function M.open_commit(worktree, ref, opts)
         return
     end
 
-    local result = vim.system(
-        { "git", "show", ref },
-        { cwd = worktree, text = true }
-    )
-        :wait()
-    if result.code ~= 0 then
-        log.error("git show %s failed: %s", ref, vim.trim(result.stderr or ""))
+    local stdout = util.system_sync({ "git", "show", ref }, { cwd = worktree })
+    if not stdout then
         return
     end
 
@@ -168,13 +163,7 @@ function M.open_commit(worktree, ref, opts)
     vim.b[buf].git_ref = sha
     vim.b[buf].git_parent_ref = parent
     vim.bo[buf].modifiable = true
-    vim.api.nvim_buf_set_lines(
-        buf,
-        0,
-        -1,
-        false,
-        util.split_lines(result.stdout or "")
-    )
+    vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
     vim.bo[buf].modifiable = false
     vim.bo[buf].modified = false
     vim.bo[buf].filetype = "git"

lua/util.lua

@@ -441,4 +441,29 @@ function M.split_lines(content)
     return lines
 end
 
+---Run a system command synchronously and return stdout on success. On
+---non-zero exit, logs stderr via `log.error` and returns nil. Pass
+---`opts.silent` to suppress the auto-log when failure is expected (e.g.
+---probe-style commands like `git rev-parse` against a possibly-missing
+---ref).
+---@param cmd string[]
+---@param opts { cwd: string?, stdin: string?, silent: boolean? }?
+---@return string?
+function M.system_sync(cmd, opts)
+    opts = opts or {}
+    local result = vim.system(cmd, {
+        cwd = opts.cwd,
+        stdin = opts.stdin,
+        text = true,
+    }):wait()
+    if result.code ~= 0 then
+        if not opts.silent then
+            local label = cmd[2] and (cmd[1] .. " " .. cmd[2]) or cmd[1] or "?"
+            log.error("%s failed: %s", label, vim.trim(result.stderr or ""))
+        end
+        return nil
+    end
+    return result.stdout or ""
+end
+
 return M