diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f80ca82da..2ded2f670 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -208,7 +208,7 @@ repos:
         entry: .pre-commit-hooks/check-open-encoding.py
         language: script
         files: \.py$
-        exclude: ^(tests/|examples/|scripts/)
+        exclude: ^tests/
         description: "Enforce explicit encoding= on text-mode open() calls (issue #3743)"
     -   id: check-image-pinning
         name: Check Docker Image Pinning
diff --git a/examples/benchmarks/browsecomp/run_browsecomp_fixed_v2.py b/examples/benchmarks/browsecomp/run_browsecomp_fixed_v2.py
index f150b7734..7c70a64a9 100755
--- a/examples/benchmarks/browsecomp/run_browsecomp_fixed_v2.py
+++ b/examples/benchmarks/browsecomp/run_browsecomp_fixed_v2.py
@@ -204,7 +204,7 @@ def run_browsecomp_evaluation(
             }
 
             # Write incrementally to output file
-            with open(output_path, "a") as f:
+            with open(output_path, "a", encoding="utf-8") as f:
                 f.write(json.dumps(result) + "\n")
 
             results.append(result)
@@ -228,7 +228,7 @@ def run_browsecomp_evaluation(
                 "confidence": "0",
                 "is_correct": False,
             }
-            with open(output_path, "a") as f:
+            with open(output_path, "a", encoding="utf-8") as f:
                 f.write(json.dumps(result) + "\n")
 
             results.append(result)
@@ -247,7 +247,7 @@ def run_browsecomp_evaluation(
     }
 
     report_path = str(Path(output_dir) / "browsecomp_summary.json")
-    with open(report_path, "w") as f:
+    with open(report_path, "w", encoding="utf-8") as f:
         json.dump(report, f, indent=2)
 
     print("\nEvaluation complete.")
diff --git a/examples/benchmarks/claude_grading/benchmark.py b/examples/benchmarks/claude_grading/benchmark.py
index 7afecafde..128691800 100755
--- a/examples/benchmarks/claude_grading/benchmark.py
+++ b/examples/benchmarks/claude_grading/benchmark.py
@@ -187,7 +187,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         # Save results
         import json
 
-        with open(Path(output_dir) / "simpleqa_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "simpleqa_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(simpleqa_results, f, indent=2)
     except Exception as e:
         print(f"Error during SimpleQA evaluation: {e}")
@@ -221,7 +223,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         print(f"BrowseComp metrics: {browsecomp_results.get('metrics', {})}")
 
         # Save results
-        with open(Path(output_dir) / "browsecomp_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "browsecomp_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(browsecomp_results, f, indent=2)
     except Exception as e:
         print(f"Error during BrowseComp evaluation: {e}")
@@ -254,7 +258,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         print(f"Composite score: {composite_results.get('score', 0):.4f}")
 
         # Save results
-        with open(Path(output_dir) / "composite_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "composite_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(composite_results, f, indent=2)
     except Exception as e:
         print(f"Error during composite evaluation: {e}")
diff --git a/examples/benchmarks/run_browsecomp.py b/examples/benchmarks/run_browsecomp.py
index adc70fb79..6c069ff18 100644
--- a/examples/benchmarks/run_browsecomp.py
+++ b/examples/benchmarks/run_browsecomp.py
@@ -170,7 +170,7 @@ def run_browsecomp_with_canary(
             results.append(result)
 
             # Write result to file
-            with open(results_file, "a") as f:
+            with open(results_file, "a", encoding="utf-8") as f:
                 f.write(json.dumps(result) + "\n")
 
         except Exception as e:
@@ -199,7 +199,7 @@ def run_browsecomp_with_canary(
             results.append(error_result)
 
             # Write error result to file
-            with open(results_file, "a") as f:
+            with open(results_file, "a", encoding="utf-8") as f:
                 f.write(json.dumps(error_result) + "\n")
 
     logger.info(f"Completed processing {total_examples} examples")
diff --git a/examples/benchmarks/run_resumable_parallel_benchmark.py b/examples/benchmarks/run_resumable_parallel_benchmark.py
index 963bbbf8d..93030e3a1 100644
--- a/examples/benchmarks/run_resumable_parallel_benchmark.py
+++ b/examples/benchmarks/run_resumable_parallel_benchmark.py
@@ -49,7 +49,7 @@ def load_existing_results(results_file: str) -> Dict[str, Dict]:
     results = {}
     if Path(results_file).exists():
         logger.info(f"Loading existing results from: {results_file}")
-        with open(results_file, "r") as f:
+        with open(results_file, "r", encoding="utf-8") as f:
             for line in f:
                 if line.strip():
                     try:
@@ -164,7 +164,7 @@ def run_resumable_benchmark(
             reused_results_count += 1
 
             # Write to new results file
-            with open(results_file, "a") as f:
+            with open(results_file, "a", encoding="utf-8") as f:
                 f.write(json.dumps(existing_result) + "\n")
         else:
             # Process new example
@@ -215,7 +215,7 @@ def run_resumable_benchmark(
                 new_results_count += 1
 
                 # Write to file immediately
-                with open(results_file, "a") as f:
+                with open(results_file, "a", encoding="utf-8") as f:
                     f.write(json.dumps(result) + "\n")
 
             except Exception as e:
@@ -235,7 +235,7 @@ def run_resumable_benchmark(
                 new_results_count += 1
 
                 # Write error result
-                with open(results_file, "a") as f:
+                with open(results_file, "a", encoding="utf-8") as f:
                     f.write(json.dumps(error_result) + "\n")
 
     logger.info(
@@ -567,7 +567,9 @@ def main():
         }
 
         with open(
-            Path(output_dir) / "parallel_benchmark_summary.json", "w"
+            Path(output_dir) / "parallel_benchmark_summary.json",
+            "w",
+            encoding="utf-8",
         ) as f:
             json.dump(summary, f, indent=2)
 
diff --git a/examples/benchmarks/scripts/run_benchmark_with_claude_grading.py b/examples/benchmarks/scripts/run_benchmark_with_claude_grading.py
index 0b2408166..4ea06a770 100755
--- a/examples/benchmarks/scripts/run_benchmark_with_claude_grading.py
+++ b/examples/benchmarks/scripts/run_benchmark_with_claude_grading.py
@@ -186,7 +186,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         # Save results
         import json
 
-        with open(Path(output_dir) / "simpleqa_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "simpleqa_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(simpleqa_results, f, indent=2)
     except Exception as e:
         print(f"Error during SimpleQA evaluation: {e}")
@@ -220,7 +222,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         print(f"BrowseComp metrics: {browsecomp_results.get('metrics', {})}")
 
         # Save results
-        with open(Path(output_dir) / "browsecomp_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "browsecomp_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(browsecomp_results, f, indent=2)
     except Exception as e:
         print(f"Error during BrowseComp evaluation: {e}")
@@ -253,7 +257,9 @@ def run_benchmark(strategy="source_based", iterations=1, examples=5):
         print(f"Composite score: {composite_results.get('score', 0):.4f}")
 
         # Save results
-        with open(Path(output_dir) / "composite_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "composite_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(composite_results, f, indent=2)
     except Exception as e:
         print(f"Error during composite evaluation: {e}")
diff --git a/examples/benchmarks/scripts/run_focused_benchmark_fixed.py b/examples/benchmarks/scripts/run_focused_benchmark_fixed.py
index 2c9fca8c8..3444e4856 100755
--- a/examples/benchmarks/scripts/run_focused_benchmark_fixed.py
+++ b/examples/benchmarks/scripts/run_focused_benchmark_fixed.py
@@ -181,7 +181,9 @@ def run_direct_evaluation(strategy="source_based", iterations=1, examples=5):
         # Save results
         import json
 
-        with open(Path(output_dir) / "simpleqa_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "simpleqa_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(simpleqa_results, f, indent=2)
     except Exception as e:
         print(f"Error during SimpleQA evaluation: {e}")
@@ -215,7 +217,9 @@ def run_direct_evaluation(strategy="source_based", iterations=1, examples=5):
         print(f"BrowseComp metrics: {browsecomp_results.get('metrics', {})}")
 
         # Save results
-        with open(Path(output_dir) / "browsecomp_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "browsecomp_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(browsecomp_results, f, indent=2)
     except Exception as e:
         print(f"Error during BrowseComp evaluation: {e}")
@@ -248,7 +252,9 @@ def run_direct_evaluation(strategy="source_based", iterations=1, examples=5):
         print(f"Composite score: {composite_results.get('score', 0):.4f}")
 
         # Save results
-        with open(Path(output_dir) / "composite_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "composite_results.json", "w", encoding="utf-8"
+        ) as f:
             json.dump(composite_results, f, indent=2)
     except Exception as e:
         print(f"Error during composite evaluation: {e}")
diff --git a/examples/benchmarks/scripts/run_grader_only.py b/examples/benchmarks/scripts/run_grader_only.py
index 0ce745535..c325537b7 100644
--- a/examples/benchmarks/scripts/run_grader_only.py
+++ b/examples/benchmarks/scripts/run_grader_only.py
@@ -201,7 +201,7 @@ def generate_summary(evaluation_path, output_dir=None):
 
         # Load evaluation results
         evaluation_results = []
-        with open(evaluation_path, "r") as f:
+        with open(evaluation_path, "r", encoding="utf-8") as f:
             for line in f:
                 if line.strip():
                     evaluation_results.append(json.loads(line))
diff --git a/examples/optimization/browsecomp_optimization.py b/examples/optimization/browsecomp_optimization.py
index 4ded57581..96a1a958b 100755
--- a/examples/optimization/browsecomp_optimization.py
+++ b/examples/optimization/browsecomp_optimization.py
@@ -92,7 +92,9 @@ def main():
     }
 
     with open(
-        Path(output_dir) / "browsecomp_optimization_summary.json", "w"
+        Path(output_dir) / "browsecomp_optimization_summary.json",
+        "w",
+        encoding="utf-8",
     ) as f:
         json.dump(summary, f, indent=2)
 
diff --git a/examples/optimization/example_optimization.py b/examples/optimization/example_optimization.py
index de6781e1c..8217b890c 100644
--- a/examples/optimization/example_optimization.py
+++ b/examples/optimization/example_optimization.py
@@ -82,7 +82,9 @@ def main():
         "demo": {"parameters": balanced_params, "score": balanced_score},
     }
 
-    with open(Path(output_dir) / "optimization_summary.json", "w") as f:
+    with open(
+        Path(output_dir) / "optimization_summary.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(summary, f, indent=2)
 
     print(f"\nDemo complete! Results saved to {output_dir}")
diff --git a/examples/optimization/example_quick_optimization.py b/examples/optimization/example_quick_optimization.py
index a80cb6d90..455ff5514 100644
--- a/examples/optimization/example_quick_optimization.py
+++ b/examples/optimization/example_quick_optimization.py
@@ -257,7 +257,9 @@ def main():
         },
     }
 
-    with open(Path(output_dir) / "optimization_summary.json", "w") as f:
+    with open(
+        Path(output_dir) / "optimization_summary.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(summary, f, indent=2)
 
     print(
diff --git a/examples/optimization/gemini_optimization.py b/examples/optimization/gemini_optimization.py
index 3d85ffb5b..889b7443d 100644
--- a/examples/optimization/gemini_optimization.py
+++ b/examples/optimization/gemini_optimization.py
@@ -195,7 +195,9 @@ def main():
         }
 
         with open(
-            Path(output_dir) / "gemini_optimization_summary.json", "w"
+            Path(output_dir) / "gemini_optimization_summary.json",
+            "w",
+            encoding="utf-8",
         ) as f:
             json.dump(summary, f, indent=2)
 
diff --git a/examples/optimization/llm_multi_benchmark.py b/examples/optimization/llm_multi_benchmark.py
index 8cdcc5c35..b59c0422b 100644
--- a/examples/optimization/llm_multi_benchmark.py
+++ b/examples/optimization/llm_multi_benchmark.py
@@ -216,7 +216,11 @@ def main():
         # Save results to file
         import json
 
-        with open(Path(output_dir) / "multi_benchmark_results.json", "w") as f:
+        with open(
+            Path(output_dir) / "multi_benchmark_results.json",
+            "w",
+            encoding="utf-8",
+        ) as f:
             json.dump(
                 {
                     "timestamp": timestamp,
diff --git a/examples/optimization/multi_benchmark_simulation.py b/examples/optimization/multi_benchmark_simulation.py
index d692f95bf..494c4764a 100644
--- a/examples/optimization/multi_benchmark_simulation.py
+++ b/examples/optimization/multi_benchmark_simulation.py
@@ -388,7 +388,7 @@ def main():
     }
 
     results_file = str(Path(output_dir) / "multi_benchmark_results.json")
-    with open(results_file, "w") as f:
+    with open(results_file, "w", encoding="utf-8") as f:
         # Convert all values to serializable types
         json.dump(
             results,
diff --git a/examples/optimization/run_gemini_benchmark.py b/examples/optimization/run_gemini_benchmark.py
index 2024058c9..1a6261583 100755
--- a/examples/optimization/run_gemini_benchmark.py
+++ b/examples/optimization/run_gemini_benchmark.py
@@ -217,7 +217,7 @@ def run_benchmarks(
     try:
         import json
 
-        with open(summary_file, "w") as f:
+        with open(summary_file, "w", encoding="utf-8") as f:
             json.dump(
                 {
                     "timestamp": timestamp,
diff --git a/examples/optimization/run_optimization.py b/examples/optimization/run_optimization.py
index c7dd87a00..3b8c69745 100644
--- a/examples/optimization/run_optimization.py
+++ b/examples/optimization/run_optimization.py
@@ -186,7 +186,9 @@ def main():
         "custom_weights": custom_weights,
     }
 
-    with open(Path(output_dir) / "optimization_summary.json", "w") as f:
+    with open(
+        Path(output_dir) / "optimization_summary.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(summary, f, indent=2)
 
     return 0
diff --git a/examples/optimization/run_parallel_benchmark.py b/examples/optimization/run_parallel_benchmark.py
index df7e903e3..2335ec2a7 100755
--- a/examples/optimization/run_parallel_benchmark.py
+++ b/examples/optimization/run_parallel_benchmark.py
@@ -284,7 +284,9 @@ def main():
         }
 
         with open(
-            Path(output_dir) / "parallel_benchmark_summary.json", "w"
+            Path(output_dir) / "parallel_benchmark_summary.json",
+            "w",
+            encoding="utf-8",
         ) as f:
             json.dump(summary, f, indent=2)
 
diff --git a/examples/optimization/strategy_benchmark_plan.py b/examples/optimization/strategy_benchmark_plan.py
index 332d43efa..db8f36b0a 100755
--- a/examples/optimization/strategy_benchmark_plan.py
+++ b/examples/optimization/strategy_benchmark_plan.py
@@ -161,7 +161,9 @@ def run_strategy_comparison():
     logger.info(f"Best quality score: {best_quality_score}")
     logger.info(f"Duration: {quality_end - quality_start} seconds")
 
-    with open(Path(quality_output_dir) / "results.json", "w") as f:
+    with open(
+        Path(quality_output_dir) / "results.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(quality_result, f, indent=2)
 
     # ====== EXPERIMENT 2: Speed-focused optimization ======
@@ -203,7 +205,9 @@ def run_strategy_comparison():
     logger.info(f"Best speed score: {best_speed_score}")
     logger.info(f"Duration: {speed_end - speed_start} seconds")
 
-    with open(Path(speed_output_dir) / "results.json", "w") as f:
+    with open(
+        Path(speed_output_dir) / "results.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(speed_result, f, indent=2)
 
     # ====== EXPERIMENT 3: Balanced optimization ======
@@ -245,7 +249,9 @@ def run_strategy_comparison():
     logger.info(f"Best balanced score: {best_balanced_score}")
     logger.info(f"Duration: {balanced_end - balanced_start} seconds")
 
-    with open(Path(balanced_output_dir) / "results.json", "w") as f:
+    with open(
+        Path(balanced_output_dir) / "results.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(balanced_result, f, indent=2)
 
     # ====== EXPERIMENT 4: Multi-Benchmark (SimpleQA + BrowseComp) ======
@@ -288,7 +294,9 @@ def run_strategy_comparison():
     logger.info(f"Best multi-benchmark score: {best_multi_score}")
     logger.info(f"Duration: {multi_end - multi_start} seconds")
 
-    with open(Path(multi_output_dir) / "results.json", "w") as f:
+    with open(
+        Path(multi_output_dir) / "results.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(multi_result, f, indent=2)
 
     # ====== Save summary of all executions ======
@@ -297,7 +305,9 @@ def run_strategy_comparison():
     )
     execution_stats["timestamp"] = timestamp
 
-    with open(Path(base_output_dir) / "summary.json", "w") as f:
+    with open(
+        Path(base_output_dir) / "summary.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(execution_stats, f, indent=2)
 
     # Generate summary report
@@ -358,7 +368,7 @@ significant sample size of 500 examples per experiment.
 """
 
     # Write summary to file
-    with open(Path(base_dir) / "summary_report.md", "w") as f:
+    with open(Path(base_dir) / "summary_report.md", "w", encoding="utf-8") as f:
         f.write(summary_text)
 
 
@@ -448,7 +458,9 @@ def run_strategy_simulation(num_examples=10):
         "best_score": best_score,
     }
 
-    with open(Path(sim_output_dir) / "simulation_results.json", "w") as f:
+    with open(
+        Path(sim_output_dir) / "simulation_results.json", "w", encoding="utf-8"
+    ) as f:
         json.dump(sim_result, f, indent=2)
 
     return sim_result
diff --git a/scripts/generate_config_docs.py b/scripts/generate_config_docs.py
index 5fe7c8f78..d2f588ba8 100755
--- a/scripts/generate_config_docs.py
+++ b/scripts/generate_config_docs.py
@@ -172,7 +172,7 @@ def get_env_only_settings(
         category = _category_from_filename(filepath.name)
 
         try:
-            content = filepath.read_text()
+            content = filepath.read_text(encoding="utf-8")
             tree = ast.parse(content)
         except Exception as e:
             print(f"Warning: Could not parse {filepath}: {e}")
@@ -221,7 +221,7 @@ def generate_docs_content(root_dir: Optional[Path] = None) -> str:
     # Recursively find all JSON files
     for json_file in sorted(defaults_dir.rglob("*.json")):
         try:
-            with open(json_file, "r") as f:
+            with open(json_file, "r", encoding="utf-8") as f:
                 data = json.load(f)
                 settings.update(data)
         except Exception as e:
@@ -344,7 +344,7 @@ def generate_docs(
                 "Run 'python scripts/generate_config_docs.py' to generate it."
             )
             return 1
-        existing = output_file.read_text()
+        existing = output_file.read_text(encoding="utf-8")
         if existing == new_content:
             print("OK: Configuration docs are up to date.")
             return 0
@@ -355,7 +355,7 @@ def generate_docs(
         return 1
 
     output_file.parent.mkdir(parents=True, exist_ok=True)
-    output_file.write_text(new_content)
+    output_file.write_text(new_content, encoding="utf-8")
     print(f"Wrote {output_file}")
     return 0
 
diff --git a/scripts/generate_workflow_status.py b/scripts/generate_workflow_status.py
index 73cb56682..d93d36365 100644
--- a/scripts/generate_workflow_status.py
+++ b/scripts/generate_workflow_status.py
@@ -172,7 +172,7 @@ def parse_workflow(path: Path) -> dict[str, Any]:
           ],
         }
     """
-    text = path.read_text()
+    text = path.read_text(encoding="utf-8")
     # Use yaml.safe_load on the file but with FullLoader behavior: the
     # `on:` key gets coerced to True (boolean) by safe_load when YAML 1.1
     # legacy boolean parsing kicks in. The simpler workaround is to load
@@ -874,7 +874,7 @@ def merge_with_existing(new_full: str, existing_path: Path) -> str:
     (including the timestamp line) is fully owned by the generator."""
     if not existing_path.exists():
         return new_full
-    existing = existing_path.read_text()
+    existing = existing_path.read_text(encoding="utf-8")
     if BEGIN_MARKER not in existing or END_MARKER not in existing:
         return new_full
     if existing.index(BEGIN_MARKER) > existing.index(END_MARKER):
@@ -1023,7 +1023,7 @@ def cmd_generate(output: Path, verbose: bool) -> int:
 
     output.parent.mkdir(parents=True, exist_ok=True)
     final = merge_with_existing(full, output)
-    output.write_text(final)
+    output.write_text(final, encoding="utf-8")
 
     counts = {k: 0 for k, _ in GROUP_ORDER}
     for wf in workflows.values():
@@ -1045,7 +1045,7 @@ def cmd_check_structure(output: Path) -> int:
             file=sys.stderr,
         )
         return 1
-    text = output.read_text()
+    text = output.read_text(encoding="utf-8")
     missing = []
     for p in sorted(WORKFLOWS_DIR.glob("*.yml")):
         if f"`{p.name}`" not in text:
diff --git a/scripts/pre_commit/check_datetime_timezone.py b/scripts/pre_commit/check_datetime_timezone.py
index dd9aa72ae..1cc20a4c6 100755
--- a/scripts/pre_commit/check_datetime_timezone.py
+++ b/scripts/pre_commit/check_datetime_timezone.py
@@ -61,7 +61,7 @@ def check_datetime_columns(file_path: Path) -> List[Tuple[int, str, str]]:
     violations = []
 
     try:
-        with open(file_path, "r") as f:
+        with open(file_path, "r", encoding="utf-8") as f:
             content = f.read()
             lines = content.split("\n")
     except Exception as e: