diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index 3c027e908c5..e448e2b18ee 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -5681,13 +5681,25 @@ def _build_web_ui(web_dir: Path, *, fatal: bool = False) -> bool:
     if not _web_ui_build_needed(web_dir):
         return True
 
+    # Console-encoding-safe print: Windows consoles default to cp1252
+    # (or similar) and will raise UnicodeEncodeError on arrow / check
+    # glyphs unless PYTHONIOENCODING=utf-8 is set. Routing every print
+    # in this function through _say() with errors="replace" keeps the
+    # build path usable on a stock `py -m hermes_cli.main web` invocation.
+    def _say(text: str) -> None:
+        try:
+            print(text)
+        except UnicodeEncodeError:
+            encoding = getattr(sys.stdout, "encoding", None) or "ascii"
+            print(text.encode(encoding, errors="replace").decode(encoding, errors="replace"))
+
     npm = shutil.which("npm")
     if not npm:
         if fatal:
-            print("Web UI frontend not built and npm is not available.")
-            print("Install Node.js, then run:  cd web && npm install && npm run build")
+            _say("Web UI frontend not built and npm is not available.")
+            _say("Install Node.js, then run:  cd web && npm install && npm run build")
         return not fatal
-    print("→ Building web UI...")
+    _say("→ Building web UI...")
 
     def _relay(result: "subprocess.CompletedProcess") -> None:
         """Print captured npm output so users can see *why* a step failed.
@@ -5702,17 +5714,17 @@ def _build_web_ui(web_dir: Path, *, fatal: bool = False) -> bool:
                 continue
             text = blob.decode("utf-8", errors="replace").rstrip() if isinstance(blob, bytes) else blob.rstrip()
             if text:
-                print(text)
+                _say(text)
 
     r1 = _run_npm_install_deterministic(npm, web_dir, extra_args=("--silent",))
     if r1.returncode != 0:
-        print(
+        _say(
             f"  {'✗' if fatal else '⚠'} Web UI npm install failed"
             + ("" if fatal else " (hermes web will not be available)")
         )
         _relay(r1)
         if fatal:
-            print("  Run manually:  cd web && npm install && npm run build")
+            _say("  Run manually:  cd web && npm install && npm run build")
         return False
     # First attempt
     r2 = subprocess.run(
@@ -5747,20 +5759,20 @@ def _build_web_ui(web_dir: Path, *, fatal: bool = False) -> bool:
         # A stale UI is far better than no UI for non-interactive callers
         # (Windows Scheduled Tasks, CI) — issue #23817.
         if dist_index.exists():
-            print("  ⚠ Web UI build failed — serving stale dist as fallback")
+            _say("  ⚠ Web UI build failed — serving stale dist as fallback")
             if stderr_tail:
-                print(f"  Build error:\n  {stderr_tail}")
+                _say(f"  Build error:\n  {stderr_tail}")
             return True
 
-        print(
+        _say(
             f"  {'✗' if fatal else '⚠'} Web UI build failed"
             + ("" if fatal else " (hermes web will not be available)")
         )
         _relay(r2)
         if fatal:
-            print("  Run manually:  cd web && npm install && npm run build")
+            _say("  Run manually:  cd web && npm install && npm run build")
         return False
-    print("  ✓ Web UI built")
+    _say("  ✓ Web UI built")
     return True