diff --git a/agent/anthropic_adapter.py b/agent/anthropic_adapter.py
index 4f7595c94d5a..d483be0d04db 100644
--- a/agent/anthropic_adapter.py
+++ b/agent/anthropic_adapter.py
@@ -878,7 +878,7 @@ def _read_claude_code_credentials_from_keychain() -> Optional[Dict[str, Any]]:
              "-s", "Claude Code-credentials",
              "-w"],
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=5,
             stdin=subprocess.DEVNULL,
         )
diff --git a/agent/coding_context.py b/agent/coding_context.py
index 78229bc4f554..7089753be564 100644
--- a/agent/coding_context.py
+++ b/agent/coding_context.py
@@ -651,7 +651,7 @@ def _git(cwd: Path, *args: str) -> str:
         out = subprocess.run(
             ["git", "-C", str(cwd), *args],
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=_GIT_TIMEOUT,
         )
     except (OSError, subprocess.SubprocessError):
diff --git a/agent/context_references.py b/agent/context_references.py
index 6307033d2706..27286a47508e 100644
--- a/agent/context_references.py
+++ b/agent/context_references.py
@@ -295,7 +295,7 @@ def _expand_git_reference(
             ["git", *args],
             cwd=cwd,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=30,
             stdin=subprocess.DEVNULL,
         )
@@ -488,7 +488,7 @@ def _rg_files(path: Path, cwd: Path, limit: int) -> list[Path] | None:
             ["rg", "--files", str(path.relative_to(cwd))],
             cwd=cwd,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=10,
             stdin=subprocess.DEVNULL,
         )
diff --git a/agent/copilot_acp_client.py b/agent/copilot_acp_client.py
index e3c03938af40..bec215d17567 100644
--- a/agent/copilot_acp_client.py
+++ b/agent/copilot_acp_client.py
@@ -435,7 +435,7 @@ def _run_prompt(self, prompt_text: str, *, timeout_seconds: float) -> tuple[str,
                 stdin=subprocess.PIPE,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
-                text=True,
+                text=True, encoding="utf-8", errors="replace",
                 bufsize=1,
                 cwd=self._acp_cwd,
                 env=_build_subprocess_env(),
diff --git a/agent/lsp/install.py b/agent/lsp/install.py
index 418cc510c709..b506a3576b06 100644
--- a/agent/lsp/install.py
+++ b/agent/lsp/install.py
@@ -260,7 +260,7 @@ def _install_npm(
             [npm, "install", "--prefix", str(staging), "--silent", "--no-fund", "--no-audit", *install_targets],
             check=False,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=300,
             stdin=subprocess.DEVNULL,
         )
@@ -308,7 +308,7 @@ def _install_go(pkg: str, bin_name: str) -> Optional[str]:
             [go, "install", pkg],
             check=False,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=600,
             env=env,
             stdin=subprocess.DEVNULL,
@@ -347,7 +347,7 @@ def _install_pip(pkg: str, bin_name: str) -> Optional[str]:
             [sys.executable, "-m", "pip", "install", "--target", str(pip_target), "--quiet", pkg],
             check=False,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=300,
             stdin=subprocess.DEVNULL,
         )
diff --git a/agent/secret_sources/bitwarden.py b/agent/secret_sources/bitwarden.py
index e025a0ca9b4e..1d6dedd21732 100644
--- a/agent/secret_sources/bitwarden.py
+++ b/agent/secret_sources/bitwarden.py
@@ -272,7 +272,7 @@ def _platform_asset_name() -> str:
             res = subprocess.run(
                 ["ldd", "--version"],
                 capture_output=True,
-                text=True,
+                text=True, encoding="utf-8", errors="replace",
                 timeout=2,
                 stdin=subprocess.DEVNULL,
             )
@@ -524,7 +524,7 @@ def _run_bws_list(
             cmd,
             env=env,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=_BWS_RUN_TIMEOUT,
             stdin=subprocess.DEVNULL,
         )
diff --git a/agent/shell_hooks.py b/agent/shell_hooks.py
index 97ba3862120b..77e39d952472 100644
--- a/agent/shell_hooks.py
+++ b/agent/shell_hooks.py
@@ -447,7 +447,7 @@ def _spawn(spec: ShellHookSpec, stdin_json: str) -> Dict[str, Any]:
             input=stdin_json,
             capture_output=True,
             timeout=spec.timeout,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             shell=False,
         )
     except subprocess.TimeoutExpired:
diff --git a/agent/skill_preprocessing.py b/agent/skill_preprocessing.py
index a7f526b25e7c..072977950aad 100644
--- a/agent/skill_preprocessing.py
+++ b/agent/skill_preprocessing.py
@@ -71,7 +71,7 @@ def run_inline_shell(command: str, cwd: Path | None, timeout: int) -> str:
             ["bash", "-c", command],
             cwd=str(cwd) if cwd else None,
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=max(1, int(timeout)),
             check=False,
             stdin=subprocess.DEVNULL,
diff --git a/agent/transports/codex_app_server.py b/agent/transports/codex_app_server.py
index dff16e971da6..9e1510fb4b42 100644
--- a/agent/transports/codex_app_server.py
+++ b/agent/transports/codex_app_server.py
@@ -376,7 +376,7 @@ def check_codex_binary(
         proc = subprocess.run(
             [codex_bin, "--version"],
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=10,
             stdin=subprocess.DEVNULL,
         )
diff --git a/gateway/run.py b/gateway/run.py
index ea0ac5c51537..6bffec768cd9 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -5471,7 +5471,7 @@ def _launch_systemd_restart_shortcut(self) -> None:
                     "--value",
                 ],
                 capture_output=True,
-                text=True,
+                text=True, encoding="utf-8", errors="replace",
                 timeout=2,
             )
             if (show.stdout or "").strip() != str(current_pid):
diff --git a/tui_gateway/git_probe.py b/tui_gateway/git_probe.py
index 01b7998ad142..9793ff9d897d 100644
--- a/tui_gateway/git_probe.py
+++ b/tui_gateway/git_probe.py
@@ -49,7 +49,7 @@ def run_git(cwd: str, *args: str) -> str:
         result = subprocess.run(
             ["git", "-C", cwd, *args],
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=_GIT_TIMEOUT,
             check=False,
             stdin=subprocess.DEVNULL,
diff --git a/tui_gateway/server.py b/tui_gateway/server.py
index 826efc9faa2f..561293ba32f0 100644
--- a/tui_gateway/server.py
+++ b/tui_gateway/server.py
@@ -271,7 +271,7 @@ def __init__(self, session_key: str, model: str):
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             bufsize=1,
             cwd=os.getcwd(),
             env=os.environ.copy(),
@@ -9044,7 +9044,7 @@ def _(rid, params: dict) -> dict:
             str(pdf_path), str(out_prefix),
         ]
         try:
-            res = subprocess.run(argv, capture_output=True, text=True, timeout=120, stdin=subprocess.DEVNULL)
+            res = subprocess.run(argv, capture_output=True, text=True, encoding="utf-8", errors="replace", timeout=120, stdin=subprocess.DEVNULL)
         except subprocess.TimeoutExpired:
             return _err(rid, 5028, "pdftoppm timed out (>120s)")
         if res.returncode != 0:
@@ -11068,7 +11068,7 @@ def _(rid, params: dict) -> dict:
         r = subprocess.run(
             [sys.executable, "-m", "hermes_cli.main", *argv],
             capture_output=True,
-            text=True,
+            text=True, encoding="utf-8", errors="replace",
             timeout=min(int(params.get("timeout", 240)), 600),
             cwd=os.getcwd(),
             env=os.environ.copy(),
@@ -11131,7 +11131,7 @@ def _(rid, params: dict) -> dict:
                 qc.get("command", ""),
                 shell=True,
                 capture_output=True,
-                text=True,
+                text=True, encoding="utf-8", errors="replace",
                 timeout=30,
                 stdin=subprocess.DEVNULL,
             )
@@ -13452,7 +13452,7 @@ def _(rid, params: dict) -> dict:
         return _err(rid, 5001, "shell.exec unavailable: approval safety module not importable")
     try:
         r = subprocess.run(
-            cmd, shell=True, capture_output=True, text=True, timeout=30, cwd=os.getcwd(),
+            cmd, shell=True, capture_output=True, text=True, encoding="utf-8", errors="replace", timeout=30, cwd=os.getcwd(),
             stdin=subprocess.DEVNULL,
         )
         return _ok(