fix: enforce utf8 resolution limits

.superpowers/sdd/2026-09-22-control-panel-operational-ux-v1/task-3-report.md

@@ -129,3 +129,44 @@ Result:
 ```
 
 The existing `pytest_asyncio` configuration and `openpyxl` print-area warnings remain unchanged.
+
+## UTF-8 Byte-Length Re-Review Fix
+
+### RED
+
+Added `test_resolution_input_rejects_multibyte_utf8_at_ascii_character_limits` before changing production code. It submits `é` repeated 512 times as `value` and 2000 times as `reason`; both are within the existing character counts but exceed the corresponding UTF-8 byte budgets.
+
+Focused command:
+
+```text
+python -m pytest central/tests/test_blocker_resolution_panel.py -q
+```
+
+RED result:
+
+```text
+1 failed, 9 passed
+```
+
+The failure confirmed character-count validation accepted the multibyte inputs.
+
+### GREEN
+
+- `value` and `reason` limits now use `len(value.encode("utf-8"))` and `len(reason.encode("utf-8"))`.
+- Existing ASCII boundary inputs remain accepted.
+- Multibyte inputs fail closed with explicit UTF-8 byte-limit validation errors, before persistence or audit sanitization.
+- Redaction and remote-write boundaries were not changed.
+
+Focused result:
+
+```text
+10 passed, 1 warning
+```
+
+Full central result:
+
+```text
+266 passed, 1 warning
+```
+
+The existing `pytest_asyncio` configuration and `openpyxl` print-area warnings remain unchanged.