P4 #5: Replace force-unwrapped URLs in AuthenticationManager with URL.api(path:) helper

[dprodger]

Context

From doc/architecture-review-2026-04.md — P4 #5.

apps/Shared/Auth/AuthenticationManager.swift has eight force-unwrapped URL constructions. The review lists the specific lines:

• Line 104
• Line 160
• Line 216
• Line 288
• Line 330
• Line 355
• Line 497
• Line 630

Each is the pattern:

let url = URL(string: "\(NetworkManager.baseURL)/auth/login")!

These work because the strings are all constants and known to parse. But:

1. A typo in any one of them crashes the app with Fatal error: Unexpectedly found nil.
2. The pattern makes it harder to grep for API paths — they are scattered across the file as interpolated strings.
3. If NetworkManager.baseURL ever becomes dynamic (different env / staging), the compiler will not help catch misuses.

Proposed fix

Add a small helper on URL:

extension URL {
    static func api(path: String) -> URL {
        guard let url = URL(string: "\(NetworkManager.baseURL)\(path)") else {
            preconditionFailure("Invalid API URL: \(NetworkManager.baseURL)\(path)")
        }
        return url
    }
}

Then replace every force-unwrap:

// Before
let url = URL(string: "\(NetworkManager.baseURL)/auth/login")!

// After
let url = URL.api(path: "/auth/login")

The preconditionFailure still crashes on an invalid URL (the behavior is identical to force-unwrap) but it gives a descriptive error instead of Fatal error: Unexpectedly found nil, and centralizes the construction so a future dynamic base URL has one place to change.

Other files to check

The review only called out AuthenticationManager.swift, but the same pattern likely exists in:

• NetworkManager.swift
• FavoritesManager.swift
• RepertoireManager.swift
• RecordingDetailViewModel.swift — has one at URL(string: "\(NetworkManager.baseURL)/recordings/\(recordingId)")

Grep for URL(string:.*baseURL and fix them all in one pass.

Not in scope

• Changing how NetworkManager.baseURL is defined or configured.
• Rewriting the request methods themselves.

Context links

• apps/Shared/Auth/AuthenticationManager.swift — the eight lines listed above
• apps/Shared/Support/NetworkManager.swift — probably has more of the same pattern
• Review doc: doc/architecture-review-2026-04.md (P4 Provide a filer for releases #5)

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