diff --git a/.jules/bolt.md b/.jules/bolt.md
index a86b7aafd..86d592a5c 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -43,3 +43,6 @@
 ## 2026-07-09 - Avoid N+1 API blocking in SBOM aggregator
 **Learning:** The `collect_inventories` function in `scripts/ci/sbom_inventory_aggregator.py` was fetching SBOMs from the GitHub dependency graph synchronously for every repository in the organization. For large organizations (up to 500 repos), this N+1 network/CLI bottleneck significantly stalled the aggregation workflow.
 **Action:** Use `concurrent.futures.ThreadPoolExecutor` to fetch SBOMs concurrently when multiple repositories are provided, bounded by a `max_workers` limit (e.g., 10) to avoid overwhelming the CLI/API, while preserving the fast serial path for single-item inputs.
+## 2026-07-28 - String Parsing Performance - Batch String Appending
+**Learning:** For Python string processing or redaction loops, avoiding character-by-character list appends (`output.append(text[cursor])`) prevents massive O(N^2) memory and runtime overhead.
+**Action:** Track a `last_append` index and use string slicing to batch-append non-matching blocks (`output.append(text[last_append:cursor])`). Note: On match failures, advance the cursor by 1 to prevent missing valid embedded tokens.
diff --git a/scripts/ci/redact_sensitive_log.py b/scripts/ci/redact_sensitive_log.py
index cb89fe67b..6b490d059 100644
--- a/scripts/ci/redact_sensitive_log.py
+++ b/scripts/ci/redact_sensitive_log.py
@@ -99,14 +99,20 @@ def _redact_assignments(text: str) -> str:
     """Redact sensitive key/value assignments without backtracking regexes."""
     output: list[str] = []
     cursor = 0
+    last_append = 0
     while cursor < len(text):
         match = _consume_sensitive_assignment(text, cursor)
         if match is None:
-            output.append(text[cursor])
             cursor += 1
             continue
-        replacement, cursor = match
+        replacement, next_cursor = match
+        # ⚡ Bolt: Use string slicing to append chunks instead of O(N^2) character-by-character appends
+        # Impact: Dramatically reduces string parsing time by avoiding unnecessary list appends
+        output.append(text[last_append:cursor])
         output.append(replacement)
+        cursor = next_cursor
+        last_append = cursor
+    output.append(text[last_append:])
     return "".join(output)