fix(auth): stop infinite SSE retry on 401/403, surface auth failures (#79)

* fix(auth): stop infinite SSE retry on 401/403 and surface auth failures

Root cause (Sentry OPENCODE-MOBILE-1, 309 events / 65 users): auth is static
HTTP Basic and no code path treated 401 specially. The SSE reconnect loop in
events.ts retried on a fixed backoff regardless of cause, so a bad password
spammed Sentry and drained battery forever with zero user feedback.
Advanced-mode connection save also had no pre-flight check and silently
persisted bad credentials as the active connection.

- src/lib/api-error.ts: new pure ApiAuthError/isAuthStatus/isAuthError module
  (node --test covered) so 401/403 are distinguishable from other failures.
- src/lib/sdk.ts: request()/events() now throw ApiAuthError for 401/403
  instead of a generic Error.
- src/stores/events.ts: the SSE loop stops retrying on an auth error and sets
  a new `authError` flag instead of reconnecting forever; other errors keep
  the existing backoff. Fires connection_failed (source: sse, error_class:
  unauthorized) so it's visible in the existing funnel.
- app/(tabs)/index.tsx: sessions screen shows an "Authentication Failed"
  state with a link to the connection edit screen when authError is set.
- app/connection/[id].tsx: saving edited credentials for the active
  connection now reconnects SSE immediately instead of requiring an app
  restart.
- app/connection/add.tsx: Advanced-mode save now runs the same testConnection
  pre-flight as Quick Connect and shows the same "Connection Failed" alert
  (with diagnostics/share-report) instead of silently saving bad credentials.

Closes #76

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NJKAQ6HAikWGQK7PGZ5Y4E

* fix(auth): add Retry button on 401 error state, widen ConnectionTestSource

- Authentication Failed screen now offers Retry alongside Check
  Credentials, calling events store's connect() directly to restart
  the SSE state machine on transient 401s without leaving the app.
- Widen ConnectionTestSource to include 'sse' (events.ts:389's
  connection_failed track call) and note the activation funnel only
  filters on source=onboarding.

Addresses PR #79 review follow-ups.

---------

Co-authored-by: engineer <engineer@gray-knight-m1.local>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/lib/analytics.ts

@@ -87,11 +87,12 @@ export enum AnalyticsEvent {
   ResponseReceived = "response_received",
 }
 
-/** Where a connection test was initiated from. The activation funnel filters
- *  to source=onboarding; edit_test covers the Test button on the existing-
- *  connection edit screen, which would otherwise pollute the funnel with
- *  repeat-tester noise. */
-export type ConnectionTestSource = "onboarding" | "edit_test"
+/** Where a connection test/failure was initiated from. The activation funnel
+ *  filters to source=onboarding only; edit_test (Test button on the
+ *  existing-connection edit screen) and sse (background reconnect loop,
+ *  see events.ts) would otherwise pollute the funnel with repeat-tester and
+ *  post-activation noise. */
+export type ConnectionTestSource = "onboarding" | "edit_test" | "sse"
 
 export function initAnalytics() {
   if (enabled) return

src/lib/api-error.test.ts

@@ -0,0 +1,42 @@
+import { test } from "node:test"
+import assert from "node:assert/strict"
+import { ApiAuthError, apiErrorFor, isAuthError, isAuthStatus } from "./api-error.ts"
+
+test("isAuthStatus: 401 and 403 are auth failures", () => {
+  assert.equal(isAuthStatus(401), true)
+  assert.equal(isAuthStatus(403), true)
+})
+
+test("isAuthStatus: other statuses are not auth failures", () => {
+  assert.equal(isAuthStatus(200), false)
+  assert.equal(isAuthStatus(404), false)
+  assert.equal(isAuthStatus(500), false)
+  assert.equal(isAuthStatus(503), false)
+  assert.equal(isAuthStatus(0), false)
+})
+
+test("apiErrorFor: 401/403 produce an ApiAuthError carrying the status", () => {
+  const err401 = apiErrorFor(401, "API Error: 401 - Unauthorized")
+  assert.ok(err401 instanceof ApiAuthError)
+  assert.equal(err401.status, 401)
+  assert.equal(err401.message, "API Error: 401 - Unauthorized")
+
+  const err403 = apiErrorFor(403, "API Error: 403 - Forbidden")
+  assert.ok(err403 instanceof ApiAuthError)
+  assert.equal(err403.status, 403)
+})
+
+test("apiErrorFor: other statuses produce a plain Error, not ApiAuthError", () => {
+  const err = apiErrorFor(500, "API Error: 500 - Internal Server Error")
+  assert.ok(err instanceof Error)
+  assert.equal(err instanceof ApiAuthError, false)
+  assert.equal(err.message, "API Error: 500 - Internal Server Error")
+})
+
+test("isAuthError: type guard matches only ApiAuthError instances", () => {
+  assert.equal(isAuthError(new ApiAuthError(401, "nope")), true)
+  assert.equal(isAuthError(new Error("some other error")), false)
+  assert.equal(isAuthError("401"), false)
+  assert.equal(isAuthError(undefined), false)
+  assert.equal(isAuthError(null), false)
+})

src/lib/api-error.ts

@@ -0,0 +1,38 @@
+// Pure classification of HTTP auth failures, extracted so it's unit-testable
+// under plain `node --test` without pulling in expo/fetch (sdk.ts is RN-only)
+// — same pattern as analytics-classify.ts / diagnostics-classify.ts.
+//
+// Why this exists: sdk.ts's request()/events() used to throw a generic Error
+// for every non-2xx response, so call sites (the SSE reconnect loop, screen
+// error states) had no way to tell "your password is wrong" apart from "the
+// server is briefly unreachable" — a 401 got treated like any transient
+// failure and retried forever (see events.ts's reconnect loop / issue #76).
+
+/** Thrown by sdk.ts's request()/events() when the server responds 401/403,
+ *  so call sites can distinguish "bad credentials" from any other failure
+ *  (network error, 5xx, timeout) instead of catching a generic Error. */
+export class ApiAuthError extends Error {
+  readonly status: number
+  constructor(status: number, message: string) {
+    super(message)
+    this.name = "ApiAuthError"
+    this.status = status
+  }
+}
+
+/** True for HTTP statuses that mean "your credentials are wrong", as opposed
+ *  to transient/network/server failures that should keep retrying. */
+export function isAuthStatus(status: number): boolean {
+  return status === 401 || status === 403
+}
+
+/** Build the right error type for a failed HTTP response. */
+export function apiErrorFor(status: number, message: string): Error {
+  return isAuthStatus(status) ? new ApiAuthError(status, message) : new Error(message)
+}
+
+/** Type guard for call sites (e.g. the SSE reconnect loop) that need to branch
+ *  on whether a caught error was an auth failure. */
+export function isAuthError(error: unknown): error is ApiAuthError {
+  return error instanceof ApiAuthError
+}

src/lib/sdk.ts

@@ -5,6 +5,9 @@
 import { fetch as expoFetch } from "expo/fetch"
 import { buildRequestHeaders } from "./headers"
 import { SSEParser } from "./sse"
+import { apiErrorFor } from "./api-error"
+
+export { ApiAuthError, isAuthError } from "./api-error"
 
 export interface ClientConfig {
   baseUrl: string
@@ -196,7 +199,7 @@ async function request<T>(config: ClientConfig, path: string, options: RequestIn
 
   if (!response.ok) {
     const error = await response.text()
-    throw new ApiError(response.status, error)
+    throw apiErrorFor(response.status, `API Error: ${response.status} - ${error}`)
   }
 
   return response.json()
@@ -243,7 +246,7 @@ export function createClient(config: ClientConfig) {
         // Must use expo/fetch for ReadableStream support on native
         const response = await expoFetch(url, { headers, signal })
         if (!response.ok || !response.body) {
-          throw new Error(`Failed to connect to event stream: ${response.status}`)
+          throw apiErrorFor(response.status, `Failed to connect to event stream: ${response.status}`)
         }
 
         const reader = response.body.getReader()