diff --git a/src/lake/Lake/Config/Cache.lean b/src/lake/Lake/Config/Cache.lean
index 7d34182ee1..371fadaa7d 100644
--- a/src/lake/Lake/Config/Cache.lean
+++ b/src/lake/Lake/Config/Cache.lean
@@ -765,12 +765,13 @@ where
       \n  remote URL: {info.url}"
     match cfg.kind with
     | .get =>
-      if let .ok size := out.getAs Nat "size_download" then
-        if size > 0 then
-          if let .ok contentType := out.getAs String "content_type" then
-            if contentType != artifactContentType then
-              if let .ok resp ← IO.FS.readFile info.path |>.toBaseIO then
-                msg := s!"{msg}\nunexpected response:\n{resp}"
+      unless code? matches .ok 404 do -- ignore response bodies on 404s
+        if let .ok size := out.getAs Nat "size_download" then
+          if size > 0 then
+            if let .ok contentType := out.getAs String "content_type" then
+              if contentType != artifactContentType then
+                if let .ok resp ← IO.FS.readFile info.path |>.toBaseIO then
+                  msg := s!"{msg}\nunexpected response:\n{resp}"
       removeFileIfExists info.path
     | .put =>
       if let .ok size := out.getAs Nat "size_download" then
@@ -787,7 +788,7 @@ private def transferArtifacts
     match cfg.kind with
     | .get =>
       cfg.infos.forM fun info => do
-        h.putStrLn s!"url = {info.url}"
+        h.putStrLn s!"url = {info.url.quote}"
         h.putStrLn s!"-o {info.path.toString.quote}"
       h.flush
       return #[
@@ -798,7 +799,7 @@ private def transferArtifacts
     | .put =>
       cfg.infos.forM fun info => do
         h.putStrLn s!"-T {info.path.toString.quote}"
-        h.putStrLn s!"url = {info.url}"
+        h.putStrLn s!"url = {info.url.quote}"
       h.flush
       return #[
         "-Z", "-X", "PUT", "-L",
@@ -827,6 +828,13 @@ private def transferArtifacts
   if s.didError then
     failure
 
+private def reservoirArtifactsUrl (service : CacheService) (scope : CacheServiceScope) : String :=
+  let endpoint :=
+    match scope.impl with
+    | .repo scope => appendScope s!"{service.impl.apiEndpoint}/repositories" scope
+    | .str scope => appendScope s!"{service.impl.apiEndpoint}/packages" scope
+  s!"{endpoint}/artifacts"
+
 public def downloadArtifacts
    (descrs : Array ArtifactDescr) (cache : Cache)
    (service : CacheService) (scope : CacheServiceScope) (force := false)
@@ -844,8 +852,69 @@ public def downloadArtifacts
     return s.push {url, path, descr}
   if infos.isEmpty then
     return
+  let infos ← id do
+    if service.isReservoir then
+      -- Artifact cloud storage URLs are fetched in a single request
+      -- to avoid hammering the Reservoir web host
+      fetchUrls (service.reservoirArtifactsUrl scope) infos
+    else return infos
   IO.FS.createDirAll cache.artifactDir
   transferArtifacts {scope, infos, kind := .get}
+where
+  fetchUrls url infos := IO.FS.withTempFile fun h path => do
+    let body := Json.arr <| infos.map (toJson ·.descr.hash)
+    h.putStr body.compress
+    h.flush
+    let args := #[
+        "-X", "POST", "-L", "-d", s!"@{path}",
+        "--retry", "3", -- intermittent network errors can occur
+        "-s", "-w", "%{stderr}%{json}\n",
+        "-H", "Content-Type: application/json",
+      ]
+    let args := Reservoir.lakeHeaders.foldl (· ++ #["-H", ·]) args
+    let child ← IO.Process.spawn {
+      cmd := "curl", args := args.push url
+      stdout := .piped, stderr := .piped
+    }
+    let rc ← child.wait
+    let stdout ← child.stdout.readToEnd
+    let stderr ← child.stderr.readToEnd
+    match Json.parse stdout >>= fromJson? with
+    | .ok (resp :  ReservoirResp (Array String)) =>
+      match resp with
+      | .data urls =>
+        if h : infos.size = urls.size then
+          let s := infos.size.fold (init := infos.toVector) fun i hi s =>
+            s.set i {s[i] with url := urls[i]'(h ▸ hi)}
+          return s.toArray
+        else
+          error s!"failed to fetch artifact URLs\
+          \n  POST {url}\
+          \nIncorrect number of results: expected {infos.size}, got {urls.size}"
+      | .error status message =>
+        error s!"failed to fetch artifact URLs (status code: {status})\
+          \n  POST {url}\
+          \nReservoir error: {message}"
+    | .error _ =>
+      match Json.parse stderr >>= fromJson? with
+      | .ok (out : JsonObject) =>
+        let mut msg := "failed to fetch artifact URLs"
+        if let .ok code := out.getAs Nat "http_code" then
+          msg := s!"{msg} (status code: {code})"
+        msg := s!"{msg}\n  POST {url}"
+        if let .ok errMsg := out.getAs String "errormsg" then
+          msg := s!"{msg}\n  Transfer error: {errMsg}"
+        unless stdout.isEmpty do
+          msg := s!"{msg}\nstdout:\n{stdout.trimAsciiEnd}"
+        logError msg
+        logVerbose s!"curl JSON:\n{stderr.trimAsciiEnd}"
+      | .error e =>
+        logError s!"failed to fetch artifact URLs\
+          \n  POST {url}
+          \nInvalid curl JSON: {e}; received: {stderr.trimAscii}"
+        unless stdout.isEmpty do
+          logWarning s!"curl produced unexpected output:\n{stdout.trimAsciiEnd}"
+      error s!"curl exited with code {rc}"
 
 @[deprecated "Deprecated without replacement." (since := "2026-02-27")]
 public def downloadOutputArtifacts
diff --git a/src/lake/Lake/Reservoir.lean b/src/lake/Lake/Reservoir.lean
index 2973a6505e..20789b581b 100644
--- a/src/lake/Lake/Reservoir.lean
+++ b/src/lake/Lake/Reservoir.lean
@@ -103,24 +103,6 @@ public instance : FromJson RegistryPkg := ⟨RegistryPkg.fromJson?⟩
 
 end RegistryPkg
 
-/-- A Reservoir API response object. -/
-public inductive ReservoirResp (α : Type u)
-| data (a : α)
-| error (status : Nat) (message : String)
-
-public protected def ReservoirResp.fromJson? [FromJson α] (val : Json) : Except String (ReservoirResp α) := do
-  let obj ← JsonObject.fromJson? val
-  if let some (err : JsonObject) ← obj.get? "error" then
-    let status ← err.get "status"
-    let message ← err.get "message"
-    return .error status message
-  else if let some (val : Json) ← obj.get? "data" then
-    .data <$> fromJson? val
-  else
-    .data <$> fromJson? val
-
-public instance [FromJson α] : FromJson (ReservoirResp α) := ⟨ReservoirResp.fromJson?⟩
-
 public def Reservoir.pkgApiUrl (lakeEnv : Lake.Env) (owner pkg : String) :=
    s!"{lakeEnv.reservoirApiUrl}/packages/{uriEncode owner}/{uriEncode pkg}"
 
diff --git a/src/lake/Lake/Util/Reservoir.lean b/src/lake/Lake/Util/Reservoir.lean
index 97c728ac7c..ab19b5e5c7 100644
--- a/src/lake/Lake/Util/Reservoir.lean
+++ b/src/lake/Lake/Util/Reservoir.lean
@@ -6,8 +6,9 @@ Authors: Mac Malone
 module
 
 prelude
-public import Init.Prelude
-import Init.Data.Array.Basic
+public import Lake.Util.JsonObject
+
+open Lean
 
 namespace Lake
 
@@ -15,3 +16,23 @@ public def Reservoir.lakeHeaders : Array String := #[
   "X-Reservoir-Api-Version:1.0.0",
   "X-Lake-Registry-Api-Version:0.1.0"
 ]
+
+/-- A Reservoir API response object. -/
+public inductive ReservoirResp (α : Type u)
+| data (a : α)
+| error (status : Nat) (message : String)
+
+public protected def ReservoirResp.fromJson? [FromJson α] (val : Json) : Except String (ReservoirResp α) := do
+  if let .ok obj := JsonObject.fromJson? val then
+    if let some (err : JsonObject) ← obj.get? "error" then
+      let status ← err.get "status"
+      let message ← err.get "message"
+      return .error status message
+    else if let some (val : Json) ← obj.get? "data" then
+      .data <$> fromJson? val
+    else
+      .data <$> fromJson? val
+  else
+    .data <$> fromJson? val
+
+public instance [FromJson α] : FromJson (ReservoirResp α) := ⟨ReservoirResp.fromJson?⟩