permissions: derive compatibility policies from profiles (#19392)

## Why

After #19391, `PermissionProfile` and the split filesystem/network
policies could still be stored in parallel. That creates drift risk: a
profile can preserve deny globs, external enforcement, or split
filesystem entries while a cached projection silently loses those
details. This PR makes the profile the runtime source and derives
compatibility views from it.

## What Changed

- Removes stored filesystem/network sandbox projections from
`Permissions` and `SessionConfiguration`; their accessors now derive
from the canonical `PermissionProfile`.
- Derives legacy `SandboxPolicy` snapshots from profiles only where an
older API still needs that field.
- Updates MCP connection and elicitation state to track
`PermissionProfile` instead of `SandboxPolicy` for auto-approval
decisions.
- Adds semantic filesystem-policy comparison so cwd changes can preserve
richer profiles while still recognizing equivalent legacy projections
independent of entry ordering.
- Updates config/session tests to assert profile-derived projections
instead of parallel stored fields.

## Verification

- `cargo test -p codex-core direct_write_roots`
- `cargo test -p codex-core runtime_roots_to_legacy_projection`
- `cargo test -p codex-app-server
requested_permissions_trust_project_uses_permission_profile_intent`



































































---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/19392).
* #19395
* #19394
* #19393
* __->__ #19392

codex-rs/protocol/src/models.rs

@@ -482,10 +482,7 @@ impl PermissionProfile {
             FileSystemSandboxKind::ExternalSandbox => Self::External {
                 network: network_sandbox_policy,
             },
-            FileSystemSandboxKind::Unrestricted
-                if enforcement == SandboxEnforcement::Disabled
-                    && network_sandbox_policy.is_enabled() =>
-            {
+            FileSystemSandboxKind::Unrestricted if enforcement == SandboxEnforcement::Disabled => {
                 Self::Disabled
             }
             FileSystemSandboxKind::Restricted | FileSystemSandboxKind::Unrestricted => {
@@ -1867,6 +1864,17 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn disabled_permission_profile_ignores_runtime_network_policy() {
+        let permission_profile = PermissionProfile::from_runtime_permissions_with_enforcement(
+            SandboxEnforcement::Disabled,
+            &FileSystemSandboxPolicy::unrestricted(),
+            NetworkSandboxPolicy::Restricted,
+        );
+
+        assert_eq!(permission_profile, PermissionProfile::Disabled);
+    }
+
     #[test]
     fn permission_profile_from_runtime_permissions_preserves_external_sandbox() {
         let permission_profile = PermissionProfile::from_runtime_permissions(

codex-rs/protocol/src/permissions.rs

@@ -631,6 +631,12 @@ impl FileSystemSandboxPolicy {
                 .semantic_signature(cwd)
     }
 
+    /// Returns true when two policies resolve to the same filesystem access
+    /// model for `cwd`, ignoring incidental entry ordering.
+    pub fn is_semantically_equivalent_to(&self, other: &Self, cwd: &Path) -> bool {
+        self.semantic_signature(cwd) == other.semantic_signature(cwd)
+    }
+
     /// Returns the explicit readable roots resolved against the provided cwd.
     pub fn get_readable_roots_with_cwd(&self, cwd: &Path) -> Vec<AbsolutePathBuf> {
         if self.has_full_disk_read_access() {
@@ -949,9 +955,9 @@ impl FileSystemSandboxPolicy {
             has_full_disk_read_access: self.has_full_disk_read_access(),
             has_full_disk_write_access: self.has_full_disk_write_access(),
             include_platform_defaults: self.include_platform_defaults(),
-            readable_roots: self.get_readable_roots_with_cwd(cwd),
-            writable_roots: self.get_writable_roots_with_cwd(cwd),
-            unreadable_roots: self.get_unreadable_roots_with_cwd(cwd),
+            readable_roots: sorted_absolute_paths(self.get_readable_roots_with_cwd(cwd)),
+            writable_roots: sorted_writable_roots(self.get_writable_roots_with_cwd(cwd)),
+            unreadable_roots: sorted_absolute_paths(self.get_unreadable_roots_with_cwd(cwd)),
             unreadable_globs: self.get_unreadable_globs_with_cwd(cwd),
         }
     }
@@ -1257,6 +1263,20 @@ fn dedup_absolute_paths(
     deduped
 }
 
+fn sorted_absolute_paths(mut paths: Vec<AbsolutePathBuf>) -> Vec<AbsolutePathBuf> {
+    paths.sort_by(|left, right| left.as_path().cmp(right.as_path()));
+    paths
+}
+
+fn sorted_writable_roots(mut roots: Vec<WritableRoot>) -> Vec<WritableRoot> {
+    for root in &mut roots {
+        root.read_only_subpaths =
+            sorted_absolute_paths(std::mem::take(&mut root.read_only_subpaths));
+    }
+    roots.sort_by(|left, right| left.root.as_path().cmp(right.root.as_path()));
+    roots
+}
+
 fn normalize_effective_absolute_path(path: AbsolutePathBuf) -> AbsolutePathBuf {
     let raw_path = path.to_path_buf();
     for ancestor in raw_path.ancestors() {
@@ -2145,6 +2165,31 @@ mod tests {
         );
     }
 
+    #[test]
+    fn legacy_projection_runtime_enforcement_ignores_entry_order() {
+        let cwd = TempDir::new().expect("tempdir");
+        let legacy_policy = SandboxPolicy::WorkspaceWrite {
+            writable_roots: Vec::new(),
+            network_access: false,
+            exclude_tmpdir_env_var: true,
+            exclude_slash_tmp: true,
+        };
+        let legacy_order =
+            FileSystemSandboxPolicy::from_legacy_sandbox_policy_for_cwd(&legacy_policy, cwd.path());
+        let mut reordered_entries = legacy_order.entries.clone();
+        reordered_entries.reverse();
+        let reordered = FileSystemSandboxPolicy::restricted(reordered_entries);
+
+        assert!(
+            legacy_order.is_semantically_equivalent_to(&reordered, cwd.path()),
+            "entry order should not affect filesystem semantics"
+        );
+        assert!(
+            !reordered
+                .needs_direct_runtime_enforcement(NetworkSandboxPolicy::Restricted, cwd.path())
+        );
+    }
+
     #[test]
     fn root_write_with_read_only_child_is_not_full_disk_write() {
         let cwd = TempDir::new().expect("tempdir");