Prompt Tuning: kanon-fake-user should search unlabeled open issues before filing duplicates

Read kanon-development/kanon-fake-user.yaml:91-93 and the surrounding pre-output review instructions. Compare the existing generated-label search with the proposed candidate-specific all-open search, then verify the prompt requires viewing likely matches and skipping creation when an open duplicate exists. Done means the prompt-only change is limited to this file and covers unlabeled duplicates.

🤖 Kelos Agent @gjkim42

Area

Prompt Tuning

Summary

kanon-fake-user can still file duplicate Kanon docs/DX issues because its pre-output review emphasizes recent issues labeled generated-by-kelos. Recent Kanon activity shows a concrete miss where the prior issue was open but did not have that label.

Evidence

• kanon-development/kanon-fake-user.yaml:91-93 says to avoid duplicates and then specifically requires reviewing recent open issues labeled generated-by-kelos with gh issue list --label generated-by-kelos --state open --limit 50 --json number,title.
• Kanon issue #55, Clarify that bare kanon import is preview-only and writes nothing, was already open and triaged when issue #60 was filed. It covers the same bare kanon import stdout-preview behavior, but #55 does not have the generated-by-kelos label.
• Kanon issue #60, Document default kanon import stdout preview, was then created by app/kelos-bot with generated-by-kelos and was later triaged as DUPLICATE of #55. The triage comment explicitly says #55 asks for the same README and kanon import --help clarification.
• A directed all-open search catches both issues now: gh issue list --repo kelos-dev/kanon --state open --search "kanon import preview stdout" --json number,title,labels returns #55 and #60. The generated-label-only list returns #60 but not #55.

This is separate from #1091 and #1142, which cover self-development prompt windows and triage scan limits. This miss is in kanon-development/kanon-fake-user.yaml and is caused by relying on a generated-label review when the duplicate can be unlabeled.

Proposed prompt change

Keep the current generated-label review for cross-agent awareness, but add a required candidate-specific duplicate search before gh issue create:

- Before creating a candidate issue, run a directed all-open duplicate search in `kelos-dev/kanon` without label filters, using distinctive terms from the candidate title and behavior:
  `gh issue list --repo kelos-dev/kanon --state open --search "<distinctive terms>" --limit 30 --json number,title,body,labels`
- Read likely matches with `gh issue view <number> --repo kelos-dev/kanon --comments`.
- If an existing open issue covers the same user-visible problem, exit without creating a new issue, even if that issue lacks `generated-by-kelos`.

Scope

One prompt-only edit under kanon-development/kanon-fake-user.yaml. No PR creation, no code changes, and no change to the fake-user focus areas.