fix(skills): honor policy table for dangerous verdicts

Salvaged from PR #1007 by stablegenius49.

- let INSTALL_POLICY decide dangerous verdict handling for builtin skills
- allow --force to override blocked dangerous decisions for trusted and community sources
- accept --yes / -y as aliases for --force in /skills install
- update regression tests to match the intended policy precedence

tests/tools/test_force_dangerous_override.py

@@ -1,11 +1,8 @@
-"""Tests for the --force flag dangerous verdict bypass fix in skills_guard.py.
+"""Regression tests for skills guard policy precedence.
 
-Regression test: the old code had `if result.verdict == "dangerous" and not force:`
-which meant force=True would skip the early return, fall through the policy
-lookup, and hit `if force: return True` - allowing installation of skills
-flagged as dangerous (reverse shells, data exfiltration, etc).
-
-The docstring explicitly states: "never overrides dangerous".
+Official/builtin skills should follow the INSTALL_POLICY table even when their
+scan verdict is dangerous, and --force should override blocked verdicts for
+non-builtin sources.
 """
 
 
@@ -44,10 +41,6 @@ def _new_should_allow(verdict, trust_level, force):
     }
     VERDICT_INDEX = {"safe": 0, "caution": 1, "dangerous": 2}
 
-    # Fixed: no `and not force` - dangerous is always blocked
-    if verdict == "dangerous":
-        return False
-
     policy = INSTALL_POLICY.get(trust_level, INSTALL_POLICY["community"])
     vi = VERDICT_INDEX.get(verdict, 2)
     decision = policy[vi]
@@ -61,35 +54,28 @@ def _new_should_allow(verdict, trust_level, force):
     return False
 
 
-class TestForceNeverOverridesDangerous:
-    """The core bug: --force bypassed the dangerous verdict block."""
+class TestPolicyPrecedenceForDangerousVerdicts:
+    def test_builtin_dangerous_is_allowed_by_policy(self):
+        assert _new_should_allow("dangerous", "builtin", force=False) is True
 
-    def test_old_code_allows_dangerous_with_force(self):
-        """Old code: force=True lets dangerous skills through."""
-        assert _old_should_allow("dangerous", "community", force=True) is True
+    def test_trusted_dangerous_is_blocked_without_force(self):
+        assert _new_should_allow("dangerous", "trusted", force=False) is False
 
-    def test_new_code_blocks_dangerous_with_force(self):
-        """Fixed code: force=True still blocks dangerous skills."""
-        assert _new_should_allow("dangerous", "community", force=True) is False
+    def test_force_overrides_dangerous_for_community(self):
+        assert _new_should_allow("dangerous", "community", force=True) is True
 
-    def test_new_code_blocks_dangerous_trusted_with_force(self):
-        """Fixed code: even trusted + force cannot install dangerous."""
-        assert _new_should_allow("dangerous", "trusted", force=True) is False
+    def test_force_overrides_dangerous_for_trusted(self):
+        assert _new_should_allow("dangerous", "trusted", force=True) is True
 
     def test_force_still_overrides_caution(self):
-        """force=True should still work for caution verdicts."""
         assert _new_should_allow("caution", "community", force=True) is True
 
     def test_caution_community_blocked_without_force(self):
-        """Caution + community is blocked without force (unchanged)."""
         assert _new_should_allow("caution", "community", force=False) is False
 
     def test_safe_always_allowed(self):
-        """Safe verdict is always allowed regardless of force."""
         assert _new_should_allow("safe", "community", force=False) is True
         assert _new_should_allow("safe", "community", force=True) is True
 
-    def test_dangerous_blocked_without_force(self):
-        """Dangerous is blocked without force (both old and new agree)."""
-        assert _old_should_allow("dangerous", "community", force=False) is False
-        assert _new_should_allow("dangerous", "community", force=False) is False
+    def test_old_code_happened_to_allow_forced_dangerous_community(self):
+        assert _old_should_allow("dangerous", "community", force=True) is True

tests/tools/test_skills_guard.py

@@ -46,9 +46,9 @@ from tools.skills_guard import (
 
 
 class TestResolveTrustLevel:
-    def test_builtin_not_exposed(self):
-        # builtin is only used internally, not resolved from source string
-        assert _resolve_trust_level("openai/skills") == "trusted"
+    def test_official_sources_resolve_to_builtin(self):
+        assert _resolve_trust_level("official") == "builtin"
+        assert _resolve_trust_level("official/email/agentmail") == "builtin"
 
     def test_trusted_repos(self):
         assert _resolve_trust_level("openai/skills") == "trusted"
@@ -116,11 +116,17 @@ class TestShouldAllowInstall:
         allowed, _ = should_allow_install(self._result("trusted", "caution", f))
         assert allowed is True
 
-    def test_dangerous_blocked_even_trusted(self):
+    def test_trusted_dangerous_blocked_without_force(self):
         f = [Finding("x", "critical", "c", "f", 1, "m", "d")]
         allowed, _ = should_allow_install(self._result("trusted", "dangerous", f))
         assert allowed is False
 
+    def test_builtin_dangerous_allowed_without_force(self):
+        f = [Finding("x", "critical", "c", "f", 1, "m", "d")]
+        allowed, reason = should_allow_install(self._result("builtin", "dangerous", f))
+        assert allowed is True
+        assert "builtin source" in reason
+
     def test_force_overrides_caution(self):
         f = [Finding("x", "high", "c", "f", 1, "m", "d")]
         allowed, reason = should_allow_install(self._result("community", "caution", f), force=True)
@@ -132,22 +138,21 @@ class TestShouldAllowInstall:
         allowed, _ = should_allow_install(self._result("community", "dangerous", f), force=False)
         assert allowed is False
 
-    def test_force_never_overrides_dangerous(self):
-        """--force must not bypass dangerous verdict (regression test)."""
+    def test_force_overrides_dangerous_for_community(self):
         f = [Finding("x", "critical", "c", "f", 1, "m", "d")]
         allowed, reason = should_allow_install(
             self._result("community", "dangerous", f), force=True
         )
-        assert allowed is False
-        assert "DANGEROUS" in reason
+        assert allowed is True
+        assert "Force-installed" in reason
 
-    def test_force_never_overrides_dangerous_trusted(self):
-        """--force must not bypass dangerous even for trusted sources."""
+    def test_force_overrides_dangerous_for_trusted(self):
         f = [Finding("x", "critical", "c", "f", 1, "m", "d")]
-        allowed, _ = should_allow_install(
+        allowed, reason = should_allow_install(
             self._result("trusted", "dangerous", f), force=True
         )
-        assert allowed is False
+        assert allowed is True
+        assert "Force-installed" in reason
 
 
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