more improvements

python/run.py

@@ -54,36 +54,28 @@ async def main() -> None:
     print(f"Fetching {len(urls)} URLs...\n")
 
     start = time.perf_counter()
+    count = 0
     try:
-        results = await fetch_all(
+        async for r in fetch_all(
             urls,
             max_concurrent=max_concurrent,
             max_requests_per_second=max_requests_per_second,
-        )
-
-        elapsed = time.perf_counter() - start
-
-        if not isinstance(results, list):
-            print(f"fetch_all returned {type(results).__name__}, expected list")
-            sys.exit(1)
-
-        print(f"Got {len(results)} results in {elapsed:.2f}s\n")
-
-        for i, r in enumerate(results):
-            if r is None:
-                print(f"  [{i}] None")
-            elif isinstance(r, Failure):
-                print(f"  [{i}] FAIL   {r.url} — {r.error}")
+        ):
+            count += 1
+            if isinstance(r, Failure):
+                print(f"  [{count}] FAIL   {r.url} — {r.error}")
             elif isinstance(r, Success):
-                print(f"  [{i}] OK     {r.url}")
+                print(f"  [{count}] OK     {r.url}")
             else:
-                print(f"  [{i}] ???    {r!r}")
-
+                print(f"  [{count}] ???    {r!r}")
     except Exception as exc:
         elapsed = time.perf_counter() - start
         print(f"\nfetch_all raised after {elapsed:.2f}s: {exc}")
         sys.exit(1)
 
+    elapsed = time.perf_counter() - start
+    print(f"\nGot {count} results in {elapsed:.2f}s")
+
     stats = _get("/stats")
     failed = False
     if stats["rateLimitViolations"] > 0:
@@ -95,6 +87,8 @@ async def main() -> None:
 
     if failed:
         sys.exit(1)
+    else:
+        print(stats)
 
 
 if __name__ == "__main__":

python/solution.py

@@ -37,7 +37,8 @@ async def fetch_all(
     *,
     max_concurrent: int,
     max_requests_per_second: int,
-) -> list[Result]:
-    """Fetch all URLs concurrently and return a Result for each, preserving order."""
+):
+    """Fetch all URLs concurrently, yielding a Result for each."""
     # TODO: implement
     raise NotImplementedError
+    yield  # makes this an async generator

python/test_harness.py

@@ -58,25 +58,23 @@ async def main() -> None:
     # Run candidate solution
     # ------------------------------------------------------------------
     start = time.perf_counter()
+    results_by_url: dict[str, object] = {}
     try:
-        results = await fetch_all(
+        async for r in fetch_all(
             urls,
             max_concurrent=10,
             max_requests_per_second=15,
-        )
+        ):
+            results_by_url[r.url] = r
     except Exception as exc:
         print(f"FAIL — fetch_all raised an exception: {exc}")
         sys.exit(1)
     elapsed = time.perf_counter() - start
 
-    # ------------------------------------------------------------------
-    # Validate return value
-    # ------------------------------------------------------------------
-    if not isinstance(results, list):
-        print(
-            f"FAIL — fetch_all must return a list, got {type(results).__name__}: {results!r}"
-        )
-        sys.exit(1)
+    results = [
+        results_by_url.get(url, Failure(url=url, error="URL was not fetched"))
+        for url in urls
+    ]
 
     # ------------------------------------------------------------------
     # Validate result shape

typescript/server.ts

@@ -80,7 +80,7 @@ type ItemHandler = (id: number, attempts: number, res: express.Response) => void
 
 /** Mode 1 — all items succeed immediately. */
 function strategyAllSuccess(id: number, _attempts: number, res: express.Response): void {
-  res.json(items[id]);
+  setTimeout(() => res.json(items[id]), 20);
 }
 
 /** Mode 2 — mixed errors and delays based on ID range. */