[core] Fix multiline log continuations without leading whitespace (#14217)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

script/ci-custom.py

@@ -841,6 +841,39 @@ def lint_no_scanf(fname, match):
     )
 
 
+LOG_MULTILINE_RE = re.compile(r"ESP_LOG\w+\s*\(.*?;", re.DOTALL)
+LOG_BAD_CONTINUATION_RE = re.compile(r'\\n(?:[^ \\"\r\n\t]|"\s*\n\s*"[^ \\])')
+LOG_PERCENT_S_CONTINUATION_RE = re.compile(r'\\n(?:%s|"\s*\n\s*"%s)')
+
+
+@lint_content_check(include=cpp_include)
+def lint_log_multiline_continuation(fname, content):
+    errs = []
+    for log_match in LOG_MULTILINE_RE.finditer(content):
+        log_text = log_match.group(0)
+        for bad_match in LOG_BAD_CONTINUATION_RE.finditer(log_text):
+            # %s may expand to a whitespace prefix at runtime, skip those
+            if LOG_PERCENT_S_CONTINUATION_RE.match(log_text, bad_match.start()):
+                continue
+            # Calculate line number from position in full content
+            abs_pos = log_match.start() + bad_match.start()
+            lineno = content.count("\n", 0, abs_pos) + 1
+            col = abs_pos - content.rfind("\n", 0, abs_pos)
+            errs.append(
+                (
+                    lineno,
+                    col,
+                    "Multi-line log message has a continuation line that does "
+                    "not start with a space. The log viewer uses leading "
+                    "whitespace to detect continuation lines and re-add the "
+                    f"log tag prefix (e.g. {highlight('[C][component:042]:')}).\n"
+                    "Either start the continuation with a space/indent, or "
+                    "split into separate ESP_LOG* calls.",
+                )
+            )
+    return errs
+
+
 @lint_content_find_check(
     "ESP_LOG",
     include=["*.h", "*.tcc"],