fix: preserve typed subtitle throttling errors

Author: Priveetee

src/main/kotlin/dev/typetype/server/Plugins.kt

@@ -7,6 +7,7 @@ import io.ktor.http.HttpMethod
 import io.ktor.http.HttpStatusCode
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.server.application.Application
+import io.ktor.server.application.ApplicationCall
 import io.ktor.server.application.install
 import io.ktor.server.plugins.calllogging.CallLogging
 import io.ktor.server.plugins.contentnegotiation.ContentNegotiation
@@ -17,6 +18,7 @@ import io.ktor.server.plugins.statuspages.StatusPages
 import io.ktor.server.request.path
 import io.ktor.server.response.respond
 import io.ktor.server.websocket.WebSockets
+import io.ktor.util.AttributeKey
 import kotlinx.serialization.json.Json
 import org.slf4j.LoggerFactory
 import kotlin.time.Duration.Companion.minutes
@@ -30,6 +32,7 @@ private const val PROXY_STORYBOARD_RATE_LIMIT = 1200
 private const val USER_DATA_RATE_LIMIT = 120
 private const val MAX_WEBSOCKET_FRAME_BYTES = 64L * 1024L * 1024L
 private val RATE_LIMIT_WINDOW = 1.minutes
+private val preserveTooManyRequestsBodyAttribute = AttributeKey<Unit>("preserveTooManyRequestsBody")
 
 val EXTRACTION_ZONE = RateLimitName("extraction")
 val DEARROW_ZONE = RateLimitName("dearrow")
@@ -40,7 +43,6 @@ val PROXY_STORYBOARD_ZONE = RateLimitName("proxy-storyboard")
 val USER_DATA_ZONE = RateLimitName("user-data")
 
 fun Application.configurePlugins(authService: AuthService) {
-    val log = LoggerFactory.getLogger("RequestLogger")
     installRequestObservability()
     install(CallLogging) {
         format(::requestLogLine)
@@ -94,8 +96,18 @@ fun Application.configurePlugins(authService: AuthService) {
             requestKey { call -> userDataRateLimitKey(call, authService) }
         }
     }
+    configureStatusPages()
+}
+
+internal fun ApplicationCall.preserveTooManyRequestsBody() {
+    attributes.put(preserveTooManyRequestsBodyAttribute, Unit)
+}
+
+internal fun Application.configureStatusPages() {
+    val log = LoggerFactory.getLogger("RequestLogger")
     install(StatusPages) {
         status(HttpStatusCode.TooManyRequests) { call, status ->
+            if (call.attributes.contains(preserveTooManyRequestsBodyAttribute)) return@status
             if (!call.response.headers.contains(HttpHeaders.RetryAfter)) call.response.headers.append(HttpHeaders.RetryAfter, "60")
             call.respond(status, ErrorResponse("Too many requests", "rate_limited"))
         }

src/main/kotlin/dev/typetype/server/routes/YouTubeSubtitleResponse.kt

@@ -1,6 +1,7 @@
 package dev.typetype.server.routes
 
 import dev.typetype.server.models.ErrorResponse
+import dev.typetype.server.preserveTooManyRequestsBody
 import dev.typetype.server.services.YouTubeSubtitleContentResult
 import io.ktor.http.ContentType
 import io.ktor.http.HttpStatusCode
@@ -47,5 +48,6 @@ private suspend fun ApplicationCall.respondSubtitleError(
     message: String,
     code: String,
 ) {
+    if (status == HttpStatusCode.TooManyRequests) preserveTooManyRequestsBody()
     respond(status, ErrorResponse(message, code))
 }

src/test/kotlin/dev/typetype/server/YouTubeSubtitleProxyRoutesTest.kt

@@ -59,6 +59,7 @@ class YouTubeSubtitleProxyRoutesTest {
         application {
             installRequestObservability()
             install(ContentNegotiation) { json(Json { encodeDefaults = true }) }
+            configureStatusPages()
             routing { proxyRoutes(proxyService, service) }
         }
 
@@ -68,6 +69,7 @@ class YouTubeSubtitleProxyRoutesTest {
         }
 
         assertEquals(HttpStatusCode.TooManyRequests, response.status)
+        assertEquals(null, response.headers[HttpHeaders.RetryAfter])
         assertEquals("subtitle-request-123", response.headers[REQUEST_ID_HEADER])
         assertEquals("subtitle-request-123", tokenRequest?.header(REQUEST_ID_HEADER))
         val body = response.bodyAsText()