diff --git a/hermes_cli/goals.py b/hermes_cli/goals.py
index 4762710cd314b..b906979e8d319 100644
--- a/hermes_cli/goals.py
+++ b/hermes_cli/goals.py
@@ -479,13 +479,15 @@ def workspace_fingerprint(cwd: Optional[str] = None) -> str:
     try:
         head = subprocess.run(
             ["git", "rev-parse", "HEAD"],
-            capture_output=True, text=True, timeout=10, cwd=workdir,
+            capture_output=True, text=True, encoding="utf-8", errors="replace",
+            timeout=10, cwd=workdir,
         )
         if head.returncode != 0:
             return ""
         status = subprocess.run(
             ["git", "status", "--porcelain"],
-            capture_output=True, text=True, timeout=30, cwd=workdir,
+            capture_output=True, text=True, encoding="utf-8", errors="replace",
+            timeout=30, cwd=workdir,
         )
         if status.returncode != 0:
             return ""
@@ -509,6 +511,14 @@ def run_gate(gate: GoalGate, *, cwd: Optional[str] = None) -> Tuple[bool, int, s
             shell=True,
             capture_output=True,
             text=True,
+            # A gate runs whatever the operator configured, so its output is
+            # arbitrary bytes. The default text mode decodes with the process
+            # codepage under errors="strict": one byte the codepage can't map
+            # (emoji or CJK from a test runner on a non-UTF-8 Windows console,
+            # or stray binary) kills the reader thread, leaves stdout as None,
+            # and the tail the agent needs to fix the failure arrives empty.
+            encoding="utf-8",
+            errors="replace",
             timeout=max(1, int(gate.timeout_seconds)),
             cwd=cwd or None,
         )
diff --git a/tests/hermes_cli/test_goal_gates.py b/tests/hermes_cli/test_goal_gates.py
index d90a63e0fb13d..4dfc79478784e 100644
--- a/tests/hermes_cli/test_goal_gates.py
+++ b/tests/hermes_cli/test_goal_gates.py
@@ -1,6 +1,7 @@
 """Tests for /goal quality gates (GoalGate, run_gate, GoalManager gate flow)."""
 
 import json
+import sys
 import time
 from unittest.mock import patch
 
@@ -77,6 +78,35 @@ def test_run_gate_timeout():
     assert "timed out" in out
 
 
+def test_run_gate_keeps_diagnostics_when_a_byte_will_not_decode(tmp_path):
+    """A gate's output tail must survive bytes the decoder rejects.
+
+    A gate runs whatever the operator configured, so its output is arbitrary
+    bytes — a test runner's checkmarks or CJK on a non-UTF-8 Windows console,
+    or stray binary. Decoding strictly means one bad byte kills subprocess's
+    reader thread, stdout comes back None, and the tail lands empty: the agent
+    is told the gate failed with nothing to act on, so it burns every retry and
+    the goal auto-pauses.
+    """
+    script = tmp_path / "gate.py"
+    script.write_text(
+        "import os, sys\n"
+        "os.write(1, b'FAILED: 3 tests broken \\x90\\x8d rerun me\\n')\n"
+        "sys.exit(1)\n",
+        encoding="utf-8",
+    )
+
+    passed, code, out = run_gate(
+        GoalGate(command=f'"{sys.executable}" "{script}"'),
+    )
+
+    assert passed is False
+    assert code == 1
+    assert "FAILED: 3 tests broken" in out, (
+        f"gate diagnostics were lost to a decode failure (tail={out!r})"
+    )
+
+
 # ──────────────────────────────────────────────────────────────────────
 # GoalManager gate management
 # ──────────────────────────────────────────────────────────────────────