[BUG] Dispatch: reasoning_extraction safeguard fires on bare 'hello' since Sept 1

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

Dispatch (Desktop, macOS) has returned "Opus 5's safeguards flagged this message
[reasoning_extraction]" on a bare "hello" since Sept 1. Request IDs:
req_011CeeiaWbU2833wn9TUejN5 (Sept 2), req_011CerCfF6kTMpxHxEbLsZNi (Sept 8 11:22),
req_011CerDgPZPQ1psNiAzL99Ys (Sept 8 11:35). Steps taken with no effect: project
CLAUDE.md reduced from 1.6MB to 28KB; every instruction mentioning "reasoning" or
"memory" reworded; app quit and reopened; Cowork storage moved to recommended
location; Notion reconnected; repo pulled clean; new conversations started. Regular
Claude Code cloud sessions on the same repo work. Dispatch has no model selector.
Separately, since Sept 6 both Cowork and Claude Code have started sessions with an
empty "continued from a previous conversation" summary. Account: Max. This blocks a
production workflow.

### What Should Happen?

Dispatch (Desktop, macOS) has returned "Opus 5's safeguards flagged this message
[reasoning_extraction]" on a bare "hello" since Sept 1. Request IDs:
req_011CeeiaWbU2833wn9TUejN5 (Sept 2), req_011CerCfF6kTMpxHxEbLsZNi (Sept 8 11:22),
req_011CerDgPZPQ1psNiAzL99Ys (Sept 8 11:35). Steps taken with no effect: project
CLAUDE.md reduced from 1.6MB to 28KB; every instruction mentioning "reasoning" or
"memory" reworded; app quit and reopened; Cowork storage moved to recommended
location; Notion reconnected; repo pulled clean; new conversations started. Regular
Claude Code cloud sessions on the same repo work. Dispatch has no model selector.
Separately, since Sept 6 both Cowork and Claude Code have started sessions with an
empty "continued from a previous conversation" summary. Account: Max. This blocks a
production workflow.

### Error Messages/Logs

```shell
API Error: Opus 5's safeguards flagged this message (https://www.anthropic.com/legal/aup). This sometimes happens with safe, normal conversations. Claude Code can't respond to this message with Opus 5.

Try rephrasing the request in a new session or change your model.

Learn more: https://support.claude.com/en/articles/16049681

Details: [reasoning_extraction]

Request ID: req_011CerDgPZPQ1psNiAzL99Ys
```

### Steps to Reproduce

just say hello to dispatch

### Claude Model

Sonnet (default)

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

_No response_

### Claude Code Version

2.1.12 (Claude Code)

### Platform

Anthropic API

### Operating System

macOS

### Terminal/Shell

Terminal.app (macOS)

### Additional Information

_No response_

No repository file, test, or entry point is named. Start by reproducing the bare "hello" in Dispatch on macOS and reviewing the reported reasoning_extraction error and request IDs. Done means the safeguard no longer blocks a harmless message and the empty continuation summary is accounted for, with regression coverage if the repository contains the relevant path.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.