fix: make Codex CLI the single writer for apply_patch

[seonhwi07jp]

Summary

This PR intentionally includes only one scope: apply_patch write-path behavior.

• Remove local patch application in CodexAgentManager approval flows.
• Keep Codex CLI as the only writer after approval.
• No parser or unified-diff algorithm change.

Why This Change Was Needed

During approval handling, AionUI could apply file edits locally before or in parallel with Codex CLI applying the same patch. That creates a dual-writer path and can desynchronize:

• engine return state vs actual file state
• verification result vs on-disk result
• especially under encoding/EOL-sensitive diffs

This is why users can observe failed result but file changed class symptoms.

Root Cause (Code Evidence)

The same patch could be written twice from two independent paths:

1. Manual confirmation path

• local decision is stored, then approval is sent to CLI (respondElicitation).
• previously this flow also applied local patch changes before approval send.
• evidence: src/process/task/CodexAgentManager.ts:395, src/process/task/CodexAgentManager.ts:411

2. Auto-approve path

• previously also executed local patch apply in fire-and-forget mode, then sent approval.
• evidence: src/process/task/CodexAgentManager.ts:636, src/process/task/CodexAgentManager.ts:640

How Gemini and Other Local Backends Handle This

In existing non-Codex managers, approval is forwarded and execution happens in the agent/worker path; manager layer does not perform a second local write.

• Gemini manager forwards confirmation via worker message only:
  • src/process/task/GeminiAgentManager.ts:656
  • src/process/task/GeminiAgentManager.ts:670
• Gemini tool scheduler separates awaiting_approval and executing states in one pipeline:
  • src/agent/gemini/cli/useReactToolScheduler.ts:125
  • src/agent/gemini/cli/useReactToolScheduler.ts:194
• ACP manager forwards confirmation to agent:
  • src/process/task/AcpAgentManager.ts:446
  • src/process/task/AcpAgentManager.ts:449
• OpenClaw manager forwards confirmation to agent:
  • src/process/task/OpenClawAgentManager.ts:204
  • src/process/task/OpenClawAgentManager.ts:209

This PR aligns Codex manager behavior with that single-writer model.

What Changed

• Removed local applyPatchChanges(...) execution from:
  • explicit confirmation path
  • auto-approve path
• Added explicit guard comments that Codex CLI is the single writer.

Scope / Risk

• Scope is minimal: 1 file (src/process/task/CodexAgentManager.ts), 1 commit.
• Low regression risk for unrelated features.
• Behavior change is targeted: write responsibility is now centralized in CLI.

Validation

• Branch diff against upstream/main contains only:
  • src/process/task/CodexAgentManager.ts
• Commit set against upstream/main contains only:
  • 787d186 (fix: make codex CLI the single writer for apply_patch)

[piorpua]

LGTM. The fix correctly removes the redundant apply_patch calls in CodexAgentManager, making Codex CLI the single writer. Clean and minimal change.

[piorpua]

Thanks for the fix @seonhwi07jp! This correctly makes Codex CLI the single writer for apply_patch, eliminating the double-write issue.

I've removed the now-dead applyPatchChanges method in #928 as a follow-up cleanup.