diff --git a/src/lake/Lake/Build/Executable.lean b/src/lake/Lake/Build/Executable.lean
index 35fa4bf09a64..0e14e4e93572 100644
--- a/src/lake/Lake/Build/Executable.lean
+++ b/src/lake/Lake/Build/Executable.lean
@@ -23,11 +23,11 @@ def LeanExe.recBuildExe (self : LeanExe) : FetchM (Job FilePath) :=
   let mut linkJobs := #[]
   for facet in self.root.nativeFacets self.supportInterpreter do
     linkJobs := linkJobs.push <| ← fetch <| self.root.facet facet.name
-  let imports ← self.root.transImports.fetch
+  let imports ← (← self.root.transImports.fetch).await
   for mod in imports do
     for facet in mod.nativeFacets self.supportInterpreter do
       linkJobs := linkJobs.push <| ← fetch <| mod.facet facet.name
-  let deps := (← fetch <| self.pkg.facet `deps).push self.pkg
+  let deps := (← (← fetch <| self.pkg.facet `deps).await).push self.pkg
   for dep in deps do for lib in dep.externLibs do
     linkJobs := linkJobs.push <| ← lib.static.fetch
   buildLeanExe self.file linkJobs self.weakLinkArgs self.linkArgs self.sharedLean
diff --git a/src/lake/Lake/Build/Imports.lean b/src/lake/Lake/Build/Imports.lean
index dd9e9c0d4bfc..df243cf6726a 100644
--- a/src/lake/Lake/Build/Imports.lean
+++ b/src/lake/Lake/Build/Imports.lean
@@ -27,7 +27,7 @@ def buildImportsAndDeps (leanFile : FilePath) (imports : Array Module) : FetchM
   else
     -- build local imports from list
     let modJob := Job.mixArray <| ← imports.mapM (·.olean.fetch)
-    let precompileImports ← computePrecompileImportsAux leanFile imports
+    let precompileImports ← (← computePrecompileImportsAux leanFile imports).await
     let pkgs := precompileImports.foldl (·.insert ·.pkg) OrdPackageSet.empty |>.toArray
     let externLibJob := Job.collectArray <| ←
       pkgs.flatMapM (·.externLibs.mapM (·.dynlib.fetch))
diff --git a/src/lake/Lake/Build/Info.lean b/src/lake/Lake/Build/Info.lean
index c87e29ab6b43..31777c0f9649 100644
--- a/src/lake/Lake/Build/Info.lean
+++ b/src/lake/Lake/Build/Info.lean
@@ -125,15 +125,15 @@ definitions.
 
 /-- The direct local imports of the Lean module. -/
 abbrev Module.importsFacet := `lean.imports
-module_data lean.imports : Array Module
+module_data lean.imports : Job (Array Module)
 
 /-- The transitive local imports of the Lean module. -/
 abbrev Module.transImportsFacet := `lean.transImports
-module_data lean.transImports : Array Module
+module_data lean.transImports : Job (Array Module)
 
 /-- The transitive local imports of the Lean module. -/
 abbrev Module.precompileImportsFacet := `lean.precompileImports
-module_data lean.precompileImports : Array Module
+module_data lean.precompileImports : Job (Array Module)
 
 /-- Shared library for `--load-dynlib`. -/
 abbrev Module.dynlibFacet := `dynlib
@@ -141,11 +141,11 @@ module_data dynlib : Job Dynlib
 
 /-- A Lean library's Lean modules. -/
 abbrev LeanLib.modulesFacet := `modules
-library_data modules : Array Module
+library_data modules : Job (Array Module)
 
 /-- The package's complete array of transitive dependencies. -/
 abbrev Package.depsFacet := `deps
-package_data deps : Array Package
+package_data deps : Job (Array Package)
 
 
 /-!
diff --git a/src/lake/Lake/Build/Job.lean b/src/lake/Lake/Build/Job.lean
index 6090f0eae9a4..b72a7314180a 100644
--- a/src/lake/Lake/Build/Job.lean
+++ b/src/lake/Lake/Build/Job.lean
@@ -32,6 +32,9 @@ def JobState.merge (a b : JobState) : JobState where
 @[inline] def JobState.modifyLog (f : Log → Log) (s : JobState) :=
   {s with log := f s.log}
 
+@[inline] def JobState.logEntry (e : LogEntry) (s : JobState) :=
+  s.modifyLog (·.push e)
+
 /-- Add log entries to the beginning of the job's log. -/
 def JobResult.prependLog (log : Log) (self : JobResult α) : JobResult α :=
   match self with
diff --git a/src/lake/Lake/Build/Library.lean b/src/lake/Lake/Build/Library.lean
index 426661e16689..4635000e7213 100644
--- a/src/lake/Lake/Build/Library.lean
+++ b/src/lake/Lake/Build/Library.lean
@@ -20,19 +20,19 @@ open System (FilePath)
 Collect the local modules of a library.
 That is, the modules from `getModuleArray` plus their local transitive imports.
 -/
-partial def LeanLib.recCollectLocalModules (self : LeanLib) : FetchM (Array Module) := do
+partial def LeanLib.recCollectLocalModules (self : LeanLib) : FetchM (Job (Array Module)) := ensureJob do
   let mut mods := #[]
   let mut modSet := ModuleSet.empty
   for mod in (← self.getModuleArray) do
     (mods, modSet) ← go mod mods modSet
-  return mods
+  return Job.pure mods
 where
   go root mods modSet := do
     let mut mods := mods
     let mut modSet := modSet
     unless modSet.contains root do
       modSet := modSet.insert root
-      let imps ← root.imports.fetch
+      let imps ← (← root.imports.fetch).await
       for mod in imps do
         if self.isLocalModule mod.name then
           (mods, modSet) ← go mod mods modSet
@@ -41,11 +41,11 @@ where
 
 /-- The `LibraryFacetConfig` for the builtin `modulesFacet`. -/
 def LeanLib.modulesFacetConfig : LibraryFacetConfig modulesFacet :=
-  mkFacetConfig LeanLib.recCollectLocalModules
+  mkFacetJobConfig LeanLib.recCollectLocalModules
 
 protected def LeanLib.recBuildLean
 (self : LeanLib) : FetchM (Job Unit) := do
-  let mods ← self.modules.fetch
+  let mods ← (← self.modules.fetch).await
   mods.foldlM (init := Job.nil) fun job mod => do
     return job.mix <| ← mod.leanArts.fetch
 
@@ -61,7 +61,7 @@ def LeanLib.leanArtsFacetConfig : LibraryFacetConfig leanArtsFacet :=
     else
       ""
   withRegisterJob s!"{self.name}:static{suffix}" do
-  let mods ← self.modules.fetch
+  let mods ← (← self.modules.fetch).await
   let oJobs ← mods.flatMapM fun mod =>
     mod.nativeFacets shouldExport |>.mapM fun facet => fetch <| mod.facet facet.name
   let libFile := if shouldExport then self.staticExportLibFile else self.staticLibFile
@@ -81,7 +81,7 @@ def LeanLib.staticExportFacetConfig : LibraryFacetConfig staticExportFacet :=
 protected def LeanLib.recBuildShared
 (self : LeanLib) : FetchM (Job FilePath) := do
   withRegisterJob s!"{self.name}:shared" do
-  let mods ← self.modules.fetch
+  let mods ← (← self.modules.fetch).await
   let oJobs ← mods.flatMapM fun mod =>
     mod.nativeFacets true |>.mapM fun facet => fetch <| mod.facet facet.name
   let pkgs := mods.foldl (·.insert ·.pkg) OrdPackageSet.empty |>.toArray
diff --git a/src/lake/Lake/Build/Module.lean b/src/lake/Lake/Build/Module.lean
index 6479d2d92381..f4bc6153d4bf 100644
--- a/src/lake/Lake/Build/Module.lean
+++ b/src/lake/Lake/Build/Module.lean
@@ -31,7 +31,8 @@ def recBuildExternDynlibs (pkgs : Array Package)
 Recursively parse the Lean files of a module and its imports
 building an `Array` product of its direct local imports.
 -/
-def Module.recParseImports (mod : Module) : FetchM (Array Module) := do
+def Module.recParseImports (mod : Module) : FetchM (Job (Array Module)) :=
+  withRegisterJob s!"{mod.name}:imports" <| Job.async do
   let contents ← IO.FS.readFile mod.leanFile
   let imports ← Lean.parseImports' contents mod.leanFile.toString
   let mods ← imports.foldlM (init := OrdModuleSet.empty) fun set imp =>
@@ -40,41 +41,52 @@ def Module.recParseImports (mod : Module) : FetchM (Array Module) := do
 
 /-- The `ModuleFacetConfig` for the builtin `importsFacet`. -/
 def Module.importsFacetConfig : ModuleFacetConfig importsFacet :=
-  mkFacetConfig (·.recParseImports)
+  mkFacetJobConfig recParseImports
+
+structure ModuleImportData where
+  module : Module
+  transImports : Job (Array Module)
+  includeSelf : Bool
 
 @[inline] def collectImportsAux
   (leanFile : FilePath) (imports : Array Module)
-  (f : Module → FetchM (Bool × Array Module))
-: FetchM (Array Module) := do
-  withLogErrorPos do
-  let mut didError := false
-  let mut importSet := OrdModuleSet.empty
-  for imp in imports do
-    try
-      let (includeSelf, transImps) ← f imp
-      importSet := importSet.appendArray transImps
-      if includeSelf then importSet := importSet.insert imp
-    catch errPos =>
-      dropLogFrom errPos
-      logError s!"{leanFile}: bad import '{imp.name}'"
-      didError := true
-  if didError then
-    failure
-  else
-    return importSet.toArray
+  (f : Module → FetchM (Bool × Job (Array Module)))
+: FetchM (Job (Array Module)) := do
+  let imps ← imports.mapM fun imp => do
+    let (includeSelf, transImports) ← f imp
+    return {module := imp, transImports, includeSelf : ModuleImportData}
+  let task : JobTask OrdModuleSet := imps.foldl (init := .pure (.ok .empty {})) fun r imp =>
+    r.bind (sync := true) fun r =>
+    imp.transImports.task.map (sync := true) fun
+    | .ok transImps _ =>
+      match r with
+      | .ok impSet s =>
+        let impSet := impSet.appendArray transImps
+        let impSet := if imp.includeSelf then impSet.insert imp.module else impSet
+        .ok impSet s
+      | .error e s => .error e s
+    | .error _ _ =>
+      let entry := LogEntry.error s!"{leanFile}: bad import '{imp.module.name}'"
+      match r with
+      | .ok _ s => .error 0 (s.logEntry entry)
+      | .error e s => .error e (s.logEntry entry)
+  return Job.ofTask <| task.map (sync := true) fun
+    | .ok impSet s => .ok impSet.toArray s
+    | .error e s => .error e s
 
 /-- Recursively compute a module's transitive imports. -/
-def Module.recComputeTransImports (mod : Module) : FetchM (Array Module) := do
-  collectImportsAux mod.leanFile (← mod.imports.fetch) fun imp =>
+def Module.recComputeTransImports (mod : Module) : FetchM (Job (Array Module)) :=
+  withRegisterJob s!"{mod.name}:transImports" do
+  collectImportsAux mod.leanFile (← (← mod.imports.fetch).await) fun imp =>
     (true, ·) <$> imp.transImports.fetch
 
 /-- The `ModuleFacetConfig` for the builtin `transImportsFacet`. -/
 def Module.transImportsFacetConfig : ModuleFacetConfig transImportsFacet :=
-  mkFacetConfig (·.recComputeTransImports)
+  mkFacetJobConfig recComputeTransImports
 
-@[inline] def computePrecompileImportsAux
+def computePrecompileImportsAux
   (leanFile : FilePath) (imports : Array Module)
-: FetchM (Array Module) := do
+: FetchM (Job (Array Module)) := do
   collectImportsAux leanFile imports fun imp =>
     if imp.shouldPrecompile then
       (true, ·) <$> imp.transImports.fetch
@@ -82,12 +94,13 @@ def Module.transImportsFacetConfig : ModuleFacetConfig transImportsFacet :=
       (false, ·) <$> imp.precompileImports.fetch
 
 /-- Recursively compute a module's precompiled imports. -/
-def Module.recComputePrecompileImports (mod : Module) : FetchM (Array Module) := do
-  computePrecompileImportsAux mod.leanFile (← mod.imports.fetch)
+def Module.recComputePrecompileImports (mod : Module) : FetchM (Job (Array Module)) :=
+  withRegisterJob s!"{mod.name}:precompileImports" do
+  inline <| computePrecompileImportsAux mod.leanFile (← (← mod.imports.fetch).await)
 
 /-- The `ModuleFacetConfig` for the builtin `precompileImportsFacet`. -/
 def Module.precompileImportsFacetConfig : ModuleFacetConfig precompileImportsFacet :=
-  mkFacetConfig (·.recComputePrecompileImports)
+  mkFacetJobConfig recComputePrecompileImports
 
 /--
 Recursively build a module's dependencies, including:
@@ -103,13 +116,14 @@ def Module.recBuildDeps (mod : Module) : FetchM (Job (SearchPath × Array FilePa
   precompiled imports so that errors in the import block of transitive imports
   will not kill this job before the direct imports are built.
   -/
-  let directImports ← mod.imports.fetch
+  let directImports ← (← mod.imports.fetch).await
   let importJob := Job.mixArray <| ← directImports.mapM fun imp => do
     if imp.name = mod.name then
       logError s!"{mod.leanFile}: module imports itself"
     imp.olean.fetch
   let precompileImports ← if mod.shouldPrecompile then
     mod.transImports.fetch else mod.precompileImports.fetch
+  let precompileImports ← precompileImports.await
   let modLibJobs ← precompileImports.mapM (·.dynlib.fetch)
   let pkgs := precompileImports.foldl (·.insert ·.pkg) OrdPackageSet.empty
   let pkgs := if mod.shouldPrecompile then pkgs.insert mod.pkg else pkgs
@@ -140,7 +154,7 @@ def Module.recBuildDeps (mod : Module) : FetchM (Job (SearchPath × Array FilePa
 
 /-- The `ModuleFacetConfig` for the builtin `depsFacet`. -/
 def Module.depsFacetConfig : ModuleFacetConfig depsFacet :=
-  mkFacetJobConfig (·.recBuildDeps)
+  mkFacetJobConfig recBuildDeps
 
 /-- Remove cached file hashes of the module build outputs (in `.hash` files). -/
 def Module.clearOutputHashes (mod : Module) : IO PUnit := do
@@ -292,7 +306,7 @@ def Module.recBuildDynlib (mod : Module) : FetchM (Job Dynlib) :=
   withRegisterJob s!"{mod.name}:dynlib" do
 
   -- Compute dependencies
-  let transImports ← mod.transImports.fetch
+  let transImports ← (← mod.transImports.fetch).await
   let modJobs ← transImports.mapM (·.dynlib.fetch)
   let pkgs := transImports.foldl (·.insert ·.pkg)
     OrdPackageSet.empty |>.insert mod.pkg |>.toArray
diff --git a/src/lake/Lake/Build/Package.lean b/src/lake/Lake/Build/Package.lean
index 6c7bd2b2e6d3..48a4e9a12d22 100644
--- a/src/lake/Lake/Build/Package.lean
+++ b/src/lake/Lake/Build/Package.lean
@@ -8,6 +8,7 @@ import Lake.Util.Git
 import Lake.Util.Sugar
 import Lake.Build.Common
 import Lake.Build.Targets
+import Lake.Build.Topological
 import Lake.Reservoir
 
 /-! # Package Facet Builds
@@ -19,16 +20,17 @@ namespace Lake
 open Lean (Name)
 
 /-- Compute a topological ordering of the package's transitive dependencies. -/
-def Package.recComputeDeps (self : Package) : FetchM (Array Package) := do
-  (·.toArray) <$> self.depConfigs.foldlM (init := OrdPackageSet.empty) fun deps cfg => do
+def Package.recComputeDeps (self : Package) : FetchM (Job (Array Package)) := ensureJob do
+  (pure ·.toArray) <$> self.depConfigs.foldlM (init := OrdPackageSet.empty) fun deps cfg => do
     let some dep ← findPackage? cfg.name
       | error s!"{self.name}: package not found for dependency '{cfg.name}' \
         (this is likely a bug in Lake)"
-    return (← fetch <| dep.facet `deps).foldl (·.insert ·) deps |>.insert dep
+    let depDeps ← (← fetch <| dep.facet `deps).await
+    return depDeps.foldl (·.insert ·) deps |>.insert dep
 
 /-- The `PackageFacetConfig` for the builtin `depsFacet`. -/
 def Package.depsFacetConfig : PackageFacetConfig depsFacet :=
-  mkFacetConfig Package.recComputeDeps
+  mkFacetJobConfig recComputeDeps
 
 /--
 Tries to download and unpack the package's cached build archive
diff --git a/src/lake/Lake/Util/Log.lean b/src/lake/Lake/Util/Log.lean
index d349df91d7ff..3e11a65e76fb 100644
--- a/src/lake/Lake/Util/Log.lean
+++ b/src/lake/Lake/Util/Log.lean
@@ -137,22 +137,34 @@ protected def LogEntry.toString (self : LogEntry) (useAnsi := false) : String :=
 
 instance : ToString LogEntry := ⟨LogEntry.toString⟩
 
+@[inline] def LogEntry.trace (message : String) : LogEntry :=
+  {level := .trace, message}
+
+@[inline] def LogEntry.info (message : String) : LogEntry :=
+  {level := .info, message}
+
+@[inline] def LogEntry.warning (message : String) : LogEntry :=
+  {level := .warning, message}
+
+@[inline] def LogEntry.error (message : String) : LogEntry :=
+  {level := .error, message}
+
 class MonadLog (m : Type u → Type v) where
   logEntry (e : LogEntry) : m PUnit
 
 export MonadLog (logEntry)
 
 @[inline] def logVerbose [Monad m] [MonadLog m] (message : String) : m PUnit := do
-  logEntry {level := .trace, message}
+  logEntry (.trace message)
 
 @[inline] def logInfo [Monad m] [MonadLog m] (message : String) : m PUnit := do
-  logEntry {level := .info, message}
+  logEntry (.info message)
 
 @[inline] def logWarning [MonadLog m] (message : String) : m PUnit :=
-  logEntry {level := .warning, message}
+  logEntry (.warning message)
 
-@[inline] def logError  [MonadLog m] (message : String) : m PUnit :=
-  logEntry {level := .error, message}
+@[inline] def logError [MonadLog m] (message : String) : m PUnit :=
+  logEntry (.error message)
 
 @[specialize] def logSerialMessage (msg : SerialMessage) [MonadLog m] : m PUnit :=
   let str := if msg.caption.trim.isEmpty then