profileArn is required for this request

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

macOS 26.5.2 (25F84)

### Expected behaviour

I have login kiro, and everything is ok, but can not use. when chat in kiro ide & kiro cli, it say:
profileArn is required for this request. (request_id:
9e2f08aa-0227-4ff4-8b5b-b10351f9408f)

### Actual behaviour

profileArn is required for this request. (request_id:
9e2f08aa-0227-4ff4-8b5b-b10351f9408f)

● profileArn is required for this request. (request_id:
9e2f08aa-0227-4ff4-8b5b-b10351f9408f)

### Steps to reproduce

_No response_

### Environment

```yaml

[q-details]
version = "2.18.1"
hash = "74b78bb5a369788e393b06654b2b213d937a41d2"
date = "2026-08-13T23:20:56.707604Z (5d ago)"
variant = "full"

[system-info]
os = "macOS 26.5.2 (25F84)"
chip = "Intel(R) Core(TM) i5-1038NG7 CPU @ 2.00GHz"
total-cores = 4
memory = "16.00 GB"

[environment]
cwd = "/Users/USER"
cli-path = "/Users/USER"
os = "Mac"
shell-path = "/bin/zsh"
shell-version = "5.9"
terminal = "macOS"
install-method = "unknown"

[env-vars]
PATH = "/usr/local/mongodb/bin:/Users/USER/.nvm/versions/node/v20.19.4/bin:/usr/local/bin:/usr/local/sbin:/Library/Application Support/Yunshu/Yunshu.app/Contents/Public:/Applications/Yunshu.app/Contents/Public:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/pkg/env/global/bin:/Library/Apple/usr/bin:/Users/USER/.local/bin"
QTERM_SESSION_ID = "f77e6e40308047558c015e3ab2ebdb95"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "2.18.1"
SHELL = "/bin/zsh"
TERM = "xterm-256color"
__CFBundleIdentifier = "com.apple.Terminal"
```

Start by reproducing the error in the Kiro IDE and CLI after running `q doctor` and `q restart`, using the reported version and macOS environment. Trace the request that reports `profileArn is required`; done means identifying the missing profileArn path and confirming chat works in both clients.

Written by the indexing model from the issue text.