fix(exec-policy) use is_known_safe_command less (#20305)

## Summary
Restricts behavior of `is_known_safe_command` only to modes where it is
explicitly part of the documented behavior:
- when `environment_lacks_sandbox_protections`
- in `AskForApproval::UnlessTrusted`

Notably, as a result of this, escalations for commands that pass
`is_known_safe_commands` are no longer auto-approved in
AskForApproval::OnRequest or AskForApproval::Granular.

## Testing
- [x] Updated unit tests
- [x] Updated approvals scenario tests.

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/tests/suite/approvals.rs

@@ -15,6 +15,7 @@ use codex_protocol::protocol::AskForApproval;
 use codex_protocol::protocol::EventMsg;
 use codex_protocol::protocol::ExecApprovalRequestEvent;
 use codex_protocol::protocol::ExecPolicyAmendment;
+use codex_protocol::protocol::GranularApprovalConfig;
 use codex_protocol::protocol::Op;
 use codex_protocol::protocol::ReviewDecision;
 use codex_protocol::protocol::SandboxPolicy;
@@ -965,6 +966,46 @@ fn scenarios() -> Vec<ScenarioSpec> {
                 output_contains: "rejected by user",
             },
         },
+        ScenarioSpec {
+            name: "known_safe_escalation_on_request_requires_approval",
+            approval_policy: OnRequest,
+            sandbox_policy: workspace_write(false),
+            action: ActionKind::RunCommand {
+                command: "echo known-safe-escalation",
+            },
+            sandbox_permissions: SandboxPermissions::RequireEscalated,
+            features: vec![],
+            model_override: Some("gpt-5.2"),
+            outcome: Outcome::ExecApprovalWithAmendment {
+                decision: ReviewDecision::Denied,
+                expected_reason: None,
+                expected_execpolicy_amendment: Some(&["echo", "known-safe-escalation"]),
+            },
+            expectation: Expectation::CommandFailure {
+                output_contains: "rejected by user",
+            },
+        },
+        ScenarioSpec {
+            name: "known_safe_escalation_granular_sandbox_disabled_rejects",
+            approval_policy: Granular(GranularApprovalConfig {
+                sandbox_approval: false,
+                rules: true,
+                skill_approval: true,
+                request_permissions: true,
+                mcp_elicitations: true,
+            }),
+            sandbox_policy: workspace_write(false),
+            action: ActionKind::RunCommand {
+                command: "echo known-safe-escalation-granular-disabled",
+            },
+            sandbox_permissions: SandboxPermissions::RequireEscalated,
+            features: vec![],
+            model_override: Some("gpt-5.2"),
+            outcome: Outcome::Auto,
+            expectation: Expectation::CommandFailure {
+                output_contains: "you should not ask for escalated permissions",
+            },
+        },
         ScenarioSpec {
             name: "cat_heredoc_file_redirect_prefix_rule_requires_escalation_approval",
             approval_policy: OnRequest,