kiro-cli v3: --no-interactive with a V2 agent exits 4 and only suggests /upgrade-agent, which a script cannot run #12110

Before opening, please confirm:

• I have searched for duplicate or closed issues

Operating System

Amazon Linux 2023 (x86_64); also macOS

Kiro Version

kiro-cli 2.34.0 (agent engine V3)

Bug Description

When chat.enableAutoAgentUpgrade is not true (it is unset on a fresh install, and stays off if the user answers "Not now" to the first-run upgrade offer), a non-interactive run with a V2-format agent fails with exit code 4:

Error: agent "v2agent" needs upgrading for this agent engine, using "default" — run /upgrade-agent to convert v2agent.json

The message points to /upgrade-agent, an interactive slash command. A non-interactive command already exists (kiro-cli agent upgrade <DIR>, with --dry-run and --no-backup) and fixes the file, but the error does not mention it. Shared agent files (zips, repos) are often still V2, so CI jobs and scripts hit this first. The text using "default" also suggests the run continues with the default agent, but it exits.

Steps to Reproduce

1. kiro-cli settings chat.enableAutoAgentUpgrade false (or use a fresh install where the key is unset).
2. In an empty folder, create .kiro/agents/v2agent.json:

   {"name":"v2agent","description":"v2 style","prompt":"You are a helper.","tools":["fs_read"],"allowedTools":["fs_read"],
    "toolsSettings":{"fs_write":{"allowedPaths":["./out/**"]}}}

3. kiro-cli chat --agent v2agent --no-interactive "Reply with only OK."; echo $?. Observed: the error above, then 4.
4. kiro-cli agent upgrade .kiro/agents. Observed: ✓ upgraded v2agent.json / 1 upgraded · 0 unchanged/skipped · 0 errors. Step 3 now succeeds.

With chat.enableAutoAgentUpgrade true, step 3 upgrades the file in place (leaving v2agent.json.bak) and succeeds.

Expected Behavior

• The error names the non-interactive fix, for example run "kiro-cli agent upgrade .kiro/agents" (or /upgrade-agent in chat).
• The message matches what happens (it exits; it does not continue with default).
• Optionally, a flag for one-shot runs that upgrades (or loads V2 configs) without changing the global setting.

Conversation ID

No response

Additional Context

Related, not the same: #11127 (/upgrade-agent leaves stale keys and .bak files).