feat(git): highlight only fatal/error lines in failure dump

lua/git/cmd.lua

@@ -321,6 +321,32 @@ local function clean_progress_line(line)
     return ""
 end
 
+---@param lines string[]
+---@param fallback string
+---@return [string, string?][]
+local function format_error_dump(lines, fallback)
+    if #lines == 0 then
+        return { { fallback, "ErrorMsg" } }
+    end
+    local chunks = {}
+    local matched = false
+    for i, line in ipairs(lines) do
+        if i > 1 then
+            table.insert(chunks, { "\n" })
+        end
+        if line:match("^fatal:") or line:match("^error:") then
+            table.insert(chunks, { line, "ErrorMsg" })
+            matched = true
+        else
+            table.insert(chunks, { line })
+        end
+    end
+    if not matched then
+        return { { table.concat(lines, "\n"), "ErrorMsg" } }
+    end
+    return chunks
+end
+
 ---@param r ow.Git.Repo
 ---@param args string[]
 local function run_streaming(r, args)
@@ -387,9 +413,8 @@ local function run_streaming(r, args)
             )
         else
             emit_progress(("exit %d"):format(code), "failed")
-            local body = #accum > 0 and table.concat(accum, "\n")
-                or ("%s failed: exit %d"):format(title, code)
-            vim.api.nvim_echo({ { body, "ErrorMsg" } }, true, {})
+            local fallback = ("%s failed: exit %d"):format(title, code)
+            vim.api.nvim_echo(format_error_dump(accum, fallback), true, {})
         end
     end
 

test/git/cmd_test.lua

@@ -550,7 +550,7 @@ t.test(
 )
 
 t.test(
-    "streaming :G fetch (no bang) on failure dumps output to :messages with ErrorMsg",
+    "streaming :G fetch (no bang) on failure highlights only fatal/error lines",
     function()
         make_repo({ a = "x" })
         with_echo_stub(function(calls)
@@ -558,24 +558,33 @@ t.test(
             t.wait_for(function()
                 return has_status(calls, "failed")
             end, "failed progress notification", 5000)
-            local body = ""
+            ---@type table?
+            local dump
             for _, c in ipairs(calls) do
-                if
-                    c.history == true
-                    and c.chunks[1]
-                    and c.chunks[1][2] == "ErrorMsg"
-                then
-                    body = c.chunks[1][1]
+                if c.history == true then
+                    dump = c.chunks
                     break
                 end
             end
-            t.truthy(body ~= "", "expected ErrorMsg history dump")
-            local lower = string.lower(body)
+            t.truthy(dump, "expected history dump")
+            ---@cast dump -nil
+            local fatal_chunks_red, plain_continuation = 0, false
+            for _, chunk in ipairs(dump) do
+                local text, hl = chunk[1], chunk[2]
+                if text:match("^fatal:") and hl == "ErrorMsg" then
+                    fatal_chunks_red = fatal_chunks_red + 1
+                end
+                if text:match("Please make sure") and hl ~= "ErrorMsg" then
+                    plain_continuation = true
+                end
+            end
             t.truthy(
-                lower:match("repository")
-                    or lower:match("remote")
-                    or lower:match("fatal"),
-                "expected error mention in dump, got: " .. body
+                fatal_chunks_red >= 1,
+                "expected at least one fatal: line highlighted as ErrorMsg"
+            )
+            t.truthy(
+                plain_continuation,
+                "expected continuation line to be plain"
             )
         end)
     end