fix: add ETag caching to UpdateChecker to avoid GitHub rate limits - #115
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Two problems caused the HTTP 403 Update check failed error: 1. No conditional request caching: every update check consumed one of GitHub's 60 unauthenticated requests/hour per IP. On shared networks (NAT, VPN, office) the pool is easily exhausted. Fixed by persisting the ETag from each 200 response and sending it as If-None-Match on subsequent requests. GitHub returns 304 Not Modified when the release hasn't changed — 304s are rate-limit free and served from CDN edge. 2. Bare User-Agent: 'VocaMac' instead of 'VocaMac/<version>'. GitHub recommends including the app version to help them identify clients. Fixed to 'VocaMac/0.5.0' (resolved at runtime from bundle). Caching strategy: - On 200 OK: persist ETag and raw JSON body to UserDefaults - On 304 Not Modified: decode and return the cached JSON body - On 304 with missing cache (UserDefaults cleared): evict ETag and surface an error so the next check gets a fresh 200 response - ETag and cache body are keyed separately so they can be cleared independently (e.g. ETag eviction on cache miss)
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Problem
Every launch logs:
Root Causes
1. No conditional request caching
Every update check consumed one of GitHub's 60 unauthenticated requests/hour per IP. On shared networks (NAT, VPN, office, CI runners) the pool is trivially exhausted — especially since the nightly build CI also hits the same API.
2. Bare User-Agent string
The request sent
User-Agent: VocaMacinstead ofUser-Agent: VocaMac/0.5.0. GitHub recommends including the app version so they can identify and contact clients that misbehave.Fix
ETag conditional caching:
ETagresponse header and raw JSON body toUserDefaultsIf-None-Match: <cached-etag>Versioned User-Agent:
VocaMac/<bundle-version>resolved at runtime.Result
Testing
All 163 tests pass.