Copilot chat shows ignored-files troubleshooting text in grep search tool completion UI

[adammw]

• Copilot Chat Extension Version: 0.57.0
• VS Code Version: 1.128.0
• Commit: fc3def6
• OS Version: Darwin arm64 25.5.0
• Feature (e.g. agent/edit/ask mode): any with grep search tool allowed
• Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): any model that uses the search tool
• Logs: (none attached)

Steps to Reproduce:

1. Open a workspace where the target files are excluded by search.exclude or ignore files.
2. In Copilot Chat agent mode, ask Copilot to search for text that will return no matches.

Expected:

The tool completion UI shows a brief user-facing no-results message.

Actual:

The chat UI shows internal troubleshooting guidance:

No matches found. Your search pattern might be excluded completely by either the search.exclude settings or .*ignore files. [...]

Additional Context:

This is user-visible in chat even though the text reads like agent guidance rather than a user-facing result message. This seems to have changed recently - previous "No matches found" did not show this guidance, likely due to the recent defaults change in #324186.

[es-mwartell]

Thanks @adammw for the pointer to #324186. I have set the flag to its old default of tag

"github.copilot.chat.tools.grepSearch.outputFormat": "tag"

which stops it from showing the big troubleshooting message. So far as I can tell, this is merely a cosmetic workaround, but what it fixes is only an aesthetic issue.