Preserve complete actions in Guardian approval reviews (#44569)

## Why

Truncating action arguments can leave approval reviewers evaluating incomplete actions. Large actions need complete review input and explicit handling when they exceed the review budget.

## What changed

- Remove action truncation and the fixed synchronous action byte limit. Admit complete actions against the whole-request budget, splitting long text losslessly into bounded transport parts and accounting for their framing.
- Route actions exceeding the asynchronous action budget to synchronous review. Prevent cached scores from covering oversized calls, including expanded approval arguments, while allowing later small actions to recover score reuse.
- Request user approval when optional review exhausts its local input budget. Keep required review and compaction service failures closed to approval, and retire exhausted review sessions.

## Testing

Add coverage for complete large-action delivery, optional user fallback, required-review denial, subsequent review recovery, async overflow through MCP approval routing, and lossless text splitting with budget accounting.

GitOrigin-RevId: 08f06e68a94b2f779480dd6b6cf5bc30b241f6dd

codex-rs/core/src/unified_exec/process_manager.rs

@@ -865,11 +865,9 @@ impl UnifiedExecProcessManager {
             .map_err(|_| unreviewable_input_error())?;
             // Bound the entire serialized action plus its reason, including JSON
             // escaping. Reject, never execute an unreviewed tail.
-            let oversized = reviewed.text.len().saturating_add(approval_reason.len())
-                > MAX_STDIN_APPROVAL_BYTES;
-            let size_check_result = if reviewed.truncated {
-                "formatter_truncated"
-            } else if oversized {
+            let oversized =
+                reviewed.len().saturating_add(approval_reason.len()) > MAX_STDIN_APPROVAL_BYTES;
+            let size_check_result = if oversized {
                 "over_limit"
             } else {
                 "within_limit"
@@ -884,7 +882,7 @@ impl UnifiedExecProcessManager {
                 /*inc*/ 1,
                 &[("result", size_check_result), ("input_kind", input_kind)],
             );
-            if reviewed.truncated || oversized {
+            if oversized {
                 return Err(unreviewable_input_error());
             }
             let approval_context = ApprovalContext {