fix(api): surface browser pool exhaustion as 429 not 500

apps/api/src/index.ts

@@ -47,26 +47,8 @@ function getDeps() {
 
 const startTime = Date.now()
 
-// Concurrency limiter — gates in-flight scrape work at exactly POOL_SIZE so we
-// reject immediately (HTTP 429) instead of letting BrowserPool.acquire() block
-// for up to 5s. Prowlarr/Jackett use the 429 to back off cleanly.
-let activeJobs = 0
-const MAX_CONCURRENT = POOL_SIZE
-
-function tryAcquireSlot(): boolean {
-  if (activeJobs < MAX_CONCURRENT) {
-    activeJobs++
-    return true
-  }
-  return false
-}
-
-function releaseSlot(): void {
-  if (activeJobs > 0) activeJobs--
-}
-
-// Build a FlareSolverr v2-shaped error envelope. Used by /v1, /scrape, and the
-// second-line PoolExhaustedError catch-arm.
+// Build a FlareSolverr v2-shaped error envelope. Used by /v1 for every error
+// path and by /scrape when the pool is exhausted (PoolExhaustedError → 429).
 function flareSolverrError(url: string, message: string): FlareSolverrResponse {
   const now = Date.now()
   return {
@@ -108,8 +90,6 @@ new Elysia()
       busy: stats.busy,
       restarts: stats.restarts,
       queueDepth: 0,
-      activeJobs,
-      maxConcurrent: MAX_CONCURRENT,
     }
   })
 
@@ -129,11 +109,6 @@ new Elysia()
       return flareSolverrError(req.url, "Browser pool initializing, retry in a few seconds")
     }
 
-    if (!tryAcquireSlot()) {
-      set.status = 429
-      return flareSolverrError(req.url, "Browser pool saturated, retry shortly")
-    }
-
     try {
       const result = await scrape({ url: req.url, maxTimeout: req.maxTimeout ?? 60_000, headers: req.headers }, getDeps())
       return {
@@ -154,32 +129,29 @@ new Elysia()
     } catch (err) {
       set.status = err instanceof PoolExhaustedError ? 429 : 500
       return flareSolverrError(req.url, err instanceof Error ? err.message : String(err))
-    } finally {
-      releaseSlot()
     }
   })
 
-  // Native TRAWL API — richer response (tier, timings, sessionCached)
+  // Native TRAWL API — richer response (tier, timings, sessionCached).
+  // Error mapping:
+  //   503 — pool still initializing (native { error })
+  //   429 — pool exhausted (FlareSolverr envelope; uniform with /v1)
+  //   500 — other scrape exception (native { error })
   .post("/scrape", async ({ body, set }) => {
     if (!pool) {
       set.status = 503
-      return flareSolverrError("", "Browser pool initializing, retry in a few seconds")
+      return { error: "Browser pool initializing, retry in a few seconds" }
     }
-
     const req = body as ScrapeRequest
-
-    if (!tryAcquireSlot()) {
-      set.status = 429
-      return flareSolverrError(req.url ?? "", "Browser pool saturated, retry shortly")
-    }
-
     try {
       return await scrape(req, getDeps())
     } catch (err) {
-      set.status = err instanceof PoolExhaustedError ? 429 : 500
-      return flareSolverrError(req.url ?? "", err instanceof Error ? err.message : String(err))
-    } finally {
-      releaseSlot()
+      if (err instanceof PoolExhaustedError) {
+        set.status = 429
+        return flareSolverrError(req.url ?? "", "Browser pool saturated, retry shortly")
+      }
+      set.status = 500
+      return { error: err instanceof Error ? err.message : String(err) }
     }
   })