hermes: bound publication titles by UTF-8 bytes

services/hermes/scripts/execution_pool_protocol.py

@@ -93,6 +93,13 @@ def payload_digest(payload: Any) -> str:
     return hashlib.sha256(canonical_json(payload)).hexdigest()
 
 
+def truncate_utf8(value: str, maximum: int) -> str:
+    """Bound display text by UTF-8 bytes without splitting a character."""
+    if maximum < 0:
+        raise ProtocolError("text byte limit is invalid")
+    return value.encode("utf-8", "replace")[:maximum].decode("utf-8", "ignore")
+
+
 def derive_ordinal_key(master: bytes, ordinal: int) -> bytes:
     """Derive one cryptographically isolated worker authority from the pool root."""
     if ordinal not in range(3) or not 32 <= len(master) <= 4096:

services/hermes/scripts/execution_pool_worker.py

@@ -19,6 +19,7 @@ from execution_pool_protocol import (
     ProtocolError,
     atomic_json,
     canonical_json,
+    truncate_utf8,
 )
 ROOT = Path(os.environ.get("HERMES_WORKER_ROOT", "/workspace"))
 ORDINAL = int(os.environ.get("HERMES_WORKER_ORDINAL", "-1"))
@@ -380,7 +381,7 @@ def execute(assignment: dict[str, Any]) -> None:
         "finish",
         binding=binding,
         payload=result_payload,
-        title=str(structured.get("summary") or f"Hermes task {binding['task_id']}")[:240],
+        title=truncate_utf8(str(structured.get("summary") or f"Hermes task {binding['task_id']}"), 512),
         body=json.dumps(structured, indent=2, sort_keys=True)[:12000],
     )
     if not response.get("ack", {}).get("accepted"):

services/hermes/scripts/scm_resume_bootstrap.py

@@ -12,7 +12,7 @@ import sys
 from pathlib import Path
 from typing import Any
 
-from execution_pool_protocol import ProtocolError, canonical_json, read_key
+from execution_pool_protocol import ProtocolError, canonical_json, read_key, truncate_utf8
 from execution_pool_scm import Boundary
 
 ROOT = Path(os.environ.get("HERMES_WORKER_ROOT", "/workspace"))
@@ -88,7 +88,7 @@ def bootstrap(key: bytes, raw_assignment: Any) -> dict[str, Any]:
     boundary = Boundary(key)
     assignment = boundary.verify(raw_assignment)
     structured = _completed_result(assignment)
-    title = structured["summary"].strip()[:512]
+    title = truncate_utf8(structured["summary"].strip(), 512)
     body = json.dumps(structured, indent=2, sort_keys=True)
     return boundary.resume_artifact(assignment, {"title": title, "body": body}, structured)
 

testing/tests/test_hermes_execution_pool_submission.py

@@ -459,6 +459,30 @@ def test_mediator_bootstrap_recovers_one_unique_nested_session_result(tmp_path,
     assert resume_bootstrap._completed_result(exact) == completed
 
 
+def test_mediator_bootstrap_truncates_multibyte_title_at_the_byte_limit(tmp_path, monkeypatch):
+    """Receipt title limits count UTF-8 bytes while preserving full evidence."""
+    exact = protocol.sign_envelope(
+        KEY, "assignment", binding(), payload(root_task_id="t_deadbeef", continuation_kind="repair")
+    )
+    log = tmp_path / "session-state" / "metis" / "t_deadbeef" / "42.log"
+    log.parent.mkdir(parents=True)
+    completed = {**RESULT, "summary": "界" * 200}
+    log.write_bytes(protocol.canonical_json({"structured_output": completed}) + b"\n")
+    monkeypatch.setattr(resume_bootstrap, "ROOT", tmp_path)
+    seen = {}
+    monkeypatch.setattr(
+        scm.Boundary, "resume_artifact",
+        lambda _self, _assignment, request, structured: seen.update(
+            request=request, structured=structured
+        ) or {},
+    )
+
+    resume_bootstrap.bootstrap(KEY, exact)
+
+    assert len(seen["request"]["title"].encode()) <= 512
+    assert seen["structured"]["summary"] == completed["summary"]
+
+
 def test_mediator_bootstrap_rejects_a_symlinked_log_ancestor(tmp_path, monkeypatch):
     exact = protocol.sign_envelope(KEY, "assignment", binding(), payload())
     outside = tmp_path / "outside"