Review Task

Commit: e716b1d4

commit e716b1d4f8ccef21c1bb171e65e26e69af948673
Author: Coder Agent <coder@agents.omni>
Date:   Mon Apr 20 12:28:31 2026

    fix(bild): handle ambiguous ghc-pkg module providers
    
    Parse ghc-pkg --simple-output as package tokens (not line blobs),
    
    normalize cached entries, and prefer explicit : dep choices when
    
    multiple packages provide the same module.
    
    Task-Id: t-809

diff --git a/Omni/Bild.hs b/Omni/Bild.hs
index e8377faa..f369d44d 100755
--- a/Omni/Bild.hs
+++ b/Omni/Bild.hs
@@ -190,6 +190,8 @@ main = Cli.Plan parser test_ pure |> Cli.main
           test_isGitHook,
           test_detectPythonImports,
           test_detectHaskellImports,
+          test_parseGhcPkgFindModuleOutput,
+          test_resolveGhcPkgCandidates,
           test_buildHsModuleGraph
         ]
 
@@ -952,7 +954,8 @@ detectHaskellImports _ contentLines = do
   (srcs, transitiveExtMods, transitiveDeps) <- bfs root initialLocalsSet Set.empty Set.empty entryLangDeps
   let allExtMods = Set.fromList initialExternals <> transitiveExtMods
   pkgSets <- Async.mapConcurrently ghcPkgFindModuleCached (Set.toList allExtMods)
-  let pkgs = mconcat pkgSets <> transitiveDeps
+  let resolvedGhcPkgs = foldMap (resolveGhcPkgCandidates transitiveDeps) pkgSets
+  let pkgs = resolvedGhcPkgs <> transitiveDeps
   pure (pkgs, srcs)
   where
     bfs :: FilePath -> Set FilePath -> Set FilePath -> Set String -> Set Meta.Dep -> IO (Set FilePath, Set String, Set Meta.Dep)
@@ -982,6 +985,13 @@ detectHaskellImports _ contentLines = do
       let rels = map (Namespace.fromHaskellModule .> Namespace.toPath) mods
       filterM (\rel -> Dir.doesFileExist (root </> rel)) rels
 
+resolveGhcPkgCandidates :: Set Meta.Dep -> Set Meta.Dep -> Set Meta.Dep
+resolveGhcPkgCandidates explicitDeps candidates
+  | Set.size candidates <= 1 = candidates
+  | otherwise =
+      let pinned = Set.intersection candidates explicitDeps
+       in Set.null pinned ?: (Set.empty, pinned)
+
 resolveLocalHaskellDep :: FilePath -> Meta.Dep -> IO (Maybe FilePath)
 resolveLocalHaskellDep root dep = do
   let normalized = fromMaybe dep (List.stripPrefix "./" dep)
@@ -1103,6 +1113,37 @@ test_detectHaskellImports =
     Set.member depRelPath srcs @=? True
     Set.member "sqlite-simple" langdeps @=? True
 
+test_parseGhcPkgFindModuleOutput :: Test.Tree
+test_parseGhcPkgFindModuleOutput =
+  Test.group
+    "parseGhcPkgFindModuleOutput"
+    [ Test.unit "splits simple-output package list" <| do
+        parseGhcPkgFindModuleOutput "base64 base64-bytestring\n"
+          @=? Set.fromList ["base64", "base64-bytestring"],
+      Test.unit "normalizes cached package names containing spaces" <| do
+        cacheFromDisk (Map.fromList [("Data.ByteString.Base64", ["base64 base64-bytestring"])])
+          @=? Map.fromList [("Data.ByteString.Base64", Set.fromList ["base64", "base64-bytestring"])]
+    ]
+
+test_resolveGhcPkgCandidates :: Test.Tree
+test_resolveGhcPkgCandidates =
+  Test.group
+    "resolveGhcPkgCandidates"
+    [ Test.unit "keeps singleton candidate set" <| do
+        resolveGhcPkgCandidates Set.empty (Set.fromList ["text"])
+          @=? Set.fromList ["text"],
+      Test.unit "prefers explicit dep for ambiguous module providers" <| do
+        resolveGhcPkgCandidates
+          (Set.fromList ["base64-bytestring"])
+          (Set.fromList ["base64", "base64-bytestring"])
+          @=? Set.fromList ["base64-bytestring"],
+      Test.unit "drops ambiguous candidates when no explicit dep exists" <| do
+        resolveGhcPkgCandidates
+          Set.empty
+          (Set.fromList ["base64", "base64-bytestring"])
+          @=? Set.empty
+    ]
+
 test_buildHsModuleGraph :: Test.Tree
 test_buildHsModuleGraph =
   Test.group
@@ -1134,7 +1175,7 @@ cacheToDisk cache =
 
 cacheFromDisk :: GhcPkgCacheDisk -> GhcPkgCacheMem
 cacheFromDisk cache =
-  Map.map Set.fromList <| Map.filter (not <. null) cache
+  Map.map (Set.fromList <. normalizePkgNames) <| Map.filter (not <. null) cache
 
 ghcPkgCacheHash :: IO (Maybe String)
 ghcPkgCacheHash = do
@@ -1212,7 +1253,13 @@ ghcPkgFindModule acc m =
           "ghc-pkg"
           ["--package-db", packageDb, "--names-only", "--simple-output", "find-module", m]
           ""
-      pure (Set.union acc (Set.fromList (String.lines out)))
+      pure (Set.union acc (parseGhcPkgFindModuleOutput out))
+
+parseGhcPkgFindModuleOutput :: String -> Set String
+parseGhcPkgFindModuleOutput = Set.fromList <. normalizePkgNames <. String.lines
+
+normalizePkgNames :: [String] -> [String]
+normalizePkgNames = concatMap String.words
 
 -- | Build module graph for Haskell targets, returns Nothing if TH or cycles detected
 buildHsModuleGraph :: Namespace -> FilePath -> Set FilePath -> IO (Maybe HsModuleGraph)