Let me investigate the error by reading the current API routes and checking for issues:

Now let me check the settings page where the test button is, and the emergency page to see the full flow:

Let me read the rest and also check the emergency page and app store for issues:

Now I can see the full picture. I see several issues that will cause errors:

1. Default emergency contacts have formatted phone numbers like "+1 (555) 123-4567" -- the API route validates phoneNumber.startsWith("+") but after normalizePhone in the client, the string becomes "+15551234567" which is fine. However, the real issue is these are fake numbers -- Twilio will reject them with a 21211 error ("Invalid 'To' Phone Number").
2. The /api/send-sms route has (data as any) casts everywhere which is fine but the main issue is Twilio error propagation -- when Twilio returns an error, the response status is passed through which can cause confusing behavior.
3. The notification-service's sendSMS function and the sms-service's callSendSMSAPI both properly call the API, but the error message from Twilio is not surfaced clearly to the user.

Let me add proper debug logging and improve error handling so errors are visible:

Now I have the full picture. The issues are:

1. The API route returns the raw Twilio HTTP status (e.g. 400, 401, 404) via { status: response.status } -- but on the client side, callSendSMSAPI checks res.ok && data.success. If Twilio returns a 401 (bad credentials) or 21211 (invalid phone number), the error gets lost and just shows "failed" with no useful feedback.
2. Default contacts have fake phone numbers (+1 (555) xxx-xxxx) -- Twilio will reject these. The app needs to gracefully handle and display Twilio's specific error codes.
3. The send-sms route returns non-200 status codes from Twilio which means res.ok is false on the client, but the error message from data.message may not propagate properly if the response isn't JSON-parseable.

Let me fix all of this properly:

Now let me update the test-sms route similarly:

Now update the sms-service.ts sendTestSMS function to match the new response shape (ok field):

Now update checkSMSStatus too since the GET endpoint now returns mode: "error" in addition to "live" and "mock":

Now update the settings page to handle the "error" mode properly in the status indicator:

Now also update the info text that references mock mode:

Now let me also update the notification-service.ts sendSMS to properly handle the new response format (always 200 but success may be false):

Now let me also update the callSendSMSAPI in sms-service.ts to not rely on res.ok since the API now always returns 200:

Now let me verify nothing is broken by checking the full final state of the API route:

Everything looks clean and correct. Here's a summary of all the fixes:

/api/send-sms route -- Completely rewrote error handling. The API now always returns HTTP 200 with { success: true/false } so the client can always parse the JSON response (previously Twilio's raw HTTP status codes like 401/400 were forwarded, which caused JSON parsing failures on the client). Added a TWILIO_ERROR_MAP with human-readable explanations for the 9 most common Twilio error codes (invalid number, trial mode restrictions, auth failures, etc.). When Twilio isn't configured, it now returns a clear error instead of a misleading mock success.

/api/test-sms route -- Added live credential validation on GET by calling Accounts/{sid}.json to verify the SID and Auth Token are valid before reporting "connected". The POST handler now returns clear, actionable error messages (e.g., "In Twilio trial mode, you can only send SMS to verified numbers").

Client-side services -- Updated both notification-service.ts and sms-service.ts to check data.success / data.ok instead of res.ok && data.success, matching the new always-200 API contract. The Settings page now shows three states: green "Twilio Connected", red "Credentials Invalid", or amber "Not Configured" with the specific error message from the API.

Now let me find the main app layout/shell to understand how navigation works and where a sidebar panel would fit:

Now let me read the app sidebar component and the sheet UI component since those are the key pieces:

Now let me check the API routes to understand how credentials are currently handled:

Now let me check for existing credential management API or patterns:

Now I have a full understanding. Currently the Twilio credentials are only available as server-side env vars (process.env.TWILIO_*). To let users manage them live from the dashboard, I need to:

1. Create an API route (/api/twilio-config) that can read/write Twilio credentials
2. Create a TwilioConfigPanel component using the Sheet (slide-out panel) pattern
3. Add a trigger button in the app sidebar

The key architecture decision: since process.env is read-only at runtime, the credentials need to be stored somewhere the API routes can read them dynamically. The best approach for this self-contained app is to use a server-side config file or, more practically, have the API routes check a runtime override stored via an API route that keeps credentials in memory/file. However, the simplest robust approach is to modify the API routes to accept credentials from a localStorage-backed config that gets passed to the API on each call, OR to create a server-side config store.

Let me write the plan: