diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,201 @@
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diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,21 @@
+# Change Type Signature Plugin
+
+The change type signature plugin provides a code action to change a user's current type signature to it's actual type signature.
+The plugin does not work in all error scenarios. Currently, the plugin uses GHC diagnostic messages to recover the actual type of a function.
+If the plugin receives enough information it can correctly change the signature.
+
+## Demo
+
+![Change Type Signature One](change1.gif)
+
+![Change Type Signature Two](change2.gif)
+
+
+## Changelog
+### 1.0.0.0
+- First Release
+
+### 1.0.1.0
+- Fix 9.2 Test failures (`waitForProgressDone`)
+- Add extra test scenarios for error message diffs in 9.2
+- Remove regex parsing for simple `Text` manipulation
diff --git a/hls-change-type-signature-plugin.cabal b/hls-change-type-signature-plugin.cabal
new file mode 100644
--- /dev/null
+++ b/hls-change-type-signature-plugin.cabal
@@ -0,0 +1,66 @@
+cabal-version:      2.4
+name:               hls-change-type-signature-plugin
+version:            1.0.1.0
+synopsis:           Change a declarations type signature with a Code Action
+description:
+  Please see the README on GitHub at <https://github.com/haskell/plugins/hls-change-type-signature-plugin/README.md>
+
+license:            Apache-2.0
+license-file:       LICENSE
+author:             Nick Suchecki
+maintainer:         nicksuchecki@gmail.com
+category:           Development
+build-type:         Simple
+extra-source-files:
+  LICENSE
+  README.md
+  test/testdata/*.hs
+  test/testdata/*.yaml
+
+library
+  exposed-modules:  Ide.Plugin.ChangeTypeSignature
+  hs-source-dirs:   src
+  build-depends:
+    , base                 >=4.12 && < 5
+    , ghcide          ^>=1.6 || ^>=1.7
+    , hls-plugin-api  ^>=1.3 || ^>=1.4
+    , lsp-types       
+    , regex-tdfa
+    , syb
+    , text
+    , transformers
+    , unordered-containers
+
+  ghc-options: -Wall
+  default-language: Haskell2010
+  default-extensions:
+    ConstraintKinds
+    DataKinds
+    ExplicitNamespaces
+    FlexibleContexts
+    NamedFieldPuns
+    OverloadedStrings
+    RecordWildCards
+    TypeOperators
+
+
+test-suite tests
+  type:             exitcode-stdio-1.0
+  default-language: Haskell2010
+  hs-source-dirs:   test
+  main-is:          Main.hs
+  ghc-options:      -threaded -rtsopts -with-rtsopts=-N -fno-ignore-asserts -Wall
+  build-depends:
+    , base                 >=4.12 && < 5
+    , filepath
+    , hls-change-type-signature-plugin
+    , hls-test-utils       ^>=1.3
+    , lsp
+    , QuickCheck
+    , regex-tdfa
+    , text
+  default-extensions:
+    NamedFieldPuns
+    OverloadedStrings
+    TypeOperators
+    ViewPatterns
diff --git a/src/Ide/Plugin/ChangeTypeSignature.hs b/src/Ide/Plugin/ChangeTypeSignature.hs
new file mode 100644
--- /dev/null
+++ b/src/Ide/Plugin/ChangeTypeSignature.hs
@@ -0,0 +1,168 @@
+{-# LANGUAGE LambdaCase   #-}
+{-# LANGUAGE ViewPatterns #-}
+-- | An HLS plugin to provide code actions to change type signatures
+module Ide.Plugin.ChangeTypeSignature (descriptor
+                                      -- * For Unit Tests
+                                      , errorMessageRegexes
+                                      ) where
+
+import           Control.Monad                  (guard)
+import           Control.Monad.IO.Class         (MonadIO (liftIO))
+import           Control.Monad.Trans.Except     (ExceptT)
+import           Data.Foldable                  (asum)
+import qualified Data.HashMap.Strict            as Map
+import           Data.Maybe                     (mapMaybe)
+import           Data.Text                      (Text)
+import qualified Data.Text                      as T
+import           Development.IDE                (realSrcSpanToRange)
+import           Development.IDE.Core.RuleTypes (GetParsedModule (GetParsedModule))
+import           Development.IDE.Core.Service   (IdeState, runAction)
+import           Development.IDE.Core.Shake     (use)
+import           Development.IDE.GHC.Compat
+import           Development.IDE.GHC.Util       (printOutputable)
+import           Generics.SYB                   (extQ, something)
+import           Ide.PluginUtils                (getNormalizedFilePath,
+                                                 handleMaybeM, response)
+import           Ide.Types                      (PluginDescriptor (..),
+                                                 PluginId, PluginMethodHandler,
+                                                 defaultPluginDescriptor,
+                                                 mkPluginHandler)
+import           Language.LSP.Types
+import           Text.Regex.TDFA                ((=~))
+
+descriptor :: PluginId -> PluginDescriptor IdeState
+descriptor plId = (defaultPluginDescriptor plId) { pluginHandlers = mkPluginHandler STextDocumentCodeAction codeActionHandler }
+
+codeActionHandler :: PluginMethodHandler IdeState 'TextDocumentCodeAction
+codeActionHandler ideState plId CodeActionParams {_textDocument = TextDocumentIdentifier uri, _context = CodeActionContext (List diags) _} = response $ do
+      nfp <- getNormalizedFilePath plId (TextDocumentIdentifier uri)
+      decls <- getDecls ideState nfp
+      let actions = mapMaybe (generateAction uri decls) diags
+      pure $ List actions
+
+getDecls :: MonadIO m => IdeState -> NormalizedFilePath -> ExceptT String m [LHsDecl GhcPs]
+getDecls state = handleMaybeM "Error: Could not get Parsed Module"
+    . liftIO
+    . fmap (fmap (hsmodDecls . unLoc . pm_parsed_source))
+    . runAction "changeSignature.GetParsedModule" state
+    . use GetParsedModule
+
+-- | Text representing a Declaration's Name
+type DeclName = Text
+-- | The signature provided by GHC Error Message (Expected type)
+type ExpectedSig = Text
+-- | The signature provided by GHC Error Message (Actual type)
+type ActualSig = Text
+
+-- | DataType that encodes the necessary information for changing a type signature
+data ChangeSignature = ChangeSignature {
+                         -- | The expected type based on Signature
+                         expectedType  :: ExpectedSig
+                         -- | the Actual Type based on definition
+                         , actualType  :: ActualSig
+                         -- | the declaration name to be updated
+                         , declName    :: DeclName
+                         -- | the location of the declaration signature
+                         , declSrcSpan :: RealSrcSpan
+                         -- | the diagnostic to solve
+                         , diagnostic  :: Diagnostic
+                         }
+
+-- | Constraint needed to trackdown OccNames in signatures
+type SigName = (HasOccName (IdP GhcPs))
+
+-- | Create a CodeAction from a Diagnostic
+generateAction :: SigName => Uri -> [LHsDecl GhcPs] -> Diagnostic -> Maybe (Command |? CodeAction)
+generateAction uri decls diag = changeSigToCodeAction uri <$> diagnosticToChangeSig decls diag
+
+-- | Convert a diagnostic into a ChangeSignature and add the proper SrcSpan
+diagnosticToChangeSig :: SigName => [LHsDecl GhcPs] -> Diagnostic -> Maybe ChangeSignature
+diagnosticToChangeSig decls diagnostic = do
+    -- regex match on the GHC Error Message
+    (expectedType, actualType, declName) <- matchingDiagnostic diagnostic
+    -- Find the definition and it's location
+    declSrcSpan <- findSigLocOfStringDecl decls expectedType (T.unpack declName)
+    pure $ ChangeSignature{..}
+
+
+-- | If a diagnostic has the proper message create a ChangeSignature from it
+matchingDiagnostic :: Diagnostic -> Maybe (ExpectedSig, ActualSig, DeclName)
+matchingDiagnostic Diagnostic{_message} = asum $ map (unwrapMatch . (=~) _message) errorMessageRegexes
+    where
+        unwrapMatch :: (Text, Text, Text, [Text]) -> Maybe (ExpectedSig, ActualSig, DeclName)
+        -- due to using (.|\n) in regex we have to drop the erroneous, but necessary ("." doesn't match newlines), match
+        unwrapMatch (_, _, _, [expect, actual, _, name]) = Just (expect, actual, name)
+        unwrapMatch _                              = Nothing
+
+-- | List of regexes that match various Error Messages
+errorMessageRegexes :: [Text]
+errorMessageRegexes = [ -- be sure to add new Error Messages Regexes at the bottom to not fail any existing tests
+    "Expected type: (.+)\n +Actual type: (.+)\n(.|\n)+In an equation for ‘(.+)’"
+    , "Couldn't match expected type ‘(.+)’ with actual type ‘(.+)’\n(.|\n)+In an equation for ‘(.+)’"
+    -- GHC >9.2 version of the first error regex
+    , "Expected: (.+)\n +Actual: (.+)\n(.|\n)+In an equation for ‘(.+)’"
+    ]
+
+-- | Given a String with the name of a declaration, GHC's "Expected Type", find the declaration that matches
+-- both the name given and the Expected Type, and return the type signature location
+findSigLocOfStringDecl :: SigName => [LHsDecl GhcPs] -> ExpectedSig -> String -> Maybe RealSrcSpan
+findSigLocOfStringDecl decls expectedType declName = something (const Nothing `extQ` findSig `extQ` findLocalSig) decls
+    where
+        -- search for Top Level Signatures
+        findSig :: LHsDecl GhcPs -> Maybe RealSrcSpan
+        findSig = \case
+            L (locA -> (RealSrcSpan rss _)) (SigD _ sig) -> case sig of
+              ts@(TypeSig _ idsSig _) -> isMatch ts idsSig >> pure rss
+              _                       -> Nothing
+            _ -> Nothing
+
+        -- search for Local Signatures
+        findLocalSig :: LSig GhcPs -> Maybe RealSrcSpan
+        findLocalSig = \case
+          (L (locA -> (RealSrcSpan rss _)) ts@(TypeSig _ idsSig _)) -> isMatch ts idsSig >> pure rss
+          _          -> Nothing
+
+        -- Does the declName match? and does the expected signature match?
+        isMatch ts idsSig = do
+                ghcSig <- sigToText ts
+                guard (any compareId idsSig && expectedType == ghcSig)
+
+        -- Given an IdP check to see if it matches the declName
+        compareId (L _ id') = declName == occNameString (occName id')
+
+
+-- | Pretty Print the Type Signature (to validate GHC Error Message)
+sigToText :: Sig GhcPs -> Maybe Text
+sigToText = \case
+  ts@TypeSig {} -> Just $ stripSignature $ printOutputable ts
+  _             -> Nothing
+
+stripSignature :: Text -> Text
+-- for whatever reason incoming signatures MAY have new lines after "::" or "=>"
+stripSignature (T.filter (/= '\n') -> sig) = if T.isInfixOf " => " sig
+                                                -- remove constraints
+                                                then T.strip $ snd $ T.breakOnEnd " => " sig
+                                                else T.strip $ snd $ T.breakOnEnd " :: " sig
+
+changeSigToCodeAction :: Uri -> ChangeSignature -> Command |? CodeAction
+changeSigToCodeAction uri ChangeSignature{..} = InR CodeAction { _title       = mkChangeSigTitle declName actualType
+                                                               , _kind        = Just (CodeActionUnknown "quickfix.changeSignature")
+                                                               , _diagnostics = Just $ List [diagnostic]
+                                                               , _isPreferred = Nothing
+                                                               , _disabled    = Nothing
+                                                               , _edit        = Just $ mkChangeSigEdit uri declSrcSpan (mkNewSignature declName actualType)
+                                                               , _command     = Nothing
+                                                               , _xdata       = Nothing
+                                                               }
+
+mkChangeSigTitle :: Text -> Text -> Text
+mkChangeSigTitle declName actualType = "Change signature for ‘" <> declName <> "’ to: " <> actualType
+
+mkChangeSigEdit :: Uri -> RealSrcSpan -> Text -> WorkspaceEdit
+mkChangeSigEdit uri ss replacement =
+        let txtEdit = TextEdit (realSrcSpanToRange ss) replacement
+            changes = Just $ Map.singleton uri (List [txtEdit])
+        in WorkspaceEdit changes Nothing Nothing
+
+mkNewSignature :: Text -> Text -> Text
+mkNewSignature declName actualType = declName <> " :: " <> actualType
diff --git a/test/Main.hs b/test/Main.hs
new file mode 100644
--- /dev/null
+++ b/test/Main.hs
@@ -0,0 +1,132 @@
+module Main where
+
+import           Control.Monad                  (void)
+import           Data.Either                    (rights)
+import           Data.Text                      (Text)
+import qualified Data.Text                      as T
+import qualified Data.Text.IO                   as TIO
+import           Ide.Plugin.ChangeTypeSignature (errorMessageRegexes)
+import qualified Ide.Plugin.ChangeTypeSignature as ChangeTypeSignature
+import           System.FilePath                ((<.>), (</>))
+import           Test.Hls                       (CodeAction (..), Command,
+                                                 GhcVersion (GHC92), IdeState,
+                                                 PluginDescriptor,
+                                                 Position (Position),
+                                                 Range (Range), Session,
+                                                 TestName, TestTree,
+                                                 TextDocumentIdentifier,
+                                                 assertFailure,
+                                                 defaultTestRunner,
+                                                 executeCodeAction,
+                                                 getCodeActions,
+                                                 goldenWithHaskellDoc,
+                                                 knownBrokenForGhcVersions,
+                                                 liftIO, openDoc,
+                                                 runSessionWithServer, testCase,
+                                                 testGroup, toEither, type (|?),
+                                                 waitForAllProgressDone,
+                                                 waitForDiagnostics, (@?=))
+import           Text.Regex.TDFA                ((=~))
+
+main :: IO ()
+main = defaultTestRunner test
+
+changeTypeSignaturePlugin :: PluginDescriptor IdeState
+changeTypeSignaturePlugin = ChangeTypeSignature.descriptor "changeTypeSignature"
+
+test :: TestTree
+test = testGroup "changeTypeSignature" [
+        testRegexes
+        , codeActionTest "TExpectedActual" 4 11
+        , knownBrokenForGhcVersions [GHC92] "Error Message in 9.2 does not provide enough info" $ codeActionTest "TRigidType" 4 14
+        , codeActionTest "TLocalBinding" 7 22
+        , codeActionTest "TLocalBindingShadow1" 11 8
+        , codeActionTest "TLocalBindingShadow2" 7 22
+        , codeActionProperties "TErrorGivenPartialSignature" [(4, 13)] $ \actions -> liftIO $ length actions @?= 0
+    ]
+
+testRegexes :: TestTree
+testRegexes = testGroup "Regex Testing" [
+        testRegexOne
+        , testRegexTwo
+        , testRegex921One
+    ]
+
+testRegexOne :: TestTree
+testRegexOne = testGroup "Regex One" [
+        regexTest "error1.txt" regex True
+        , regexTest "error2.txt" regex True
+        , regexTest "error3.txt" regex False
+        , regexTest "error4.txt" regex True
+        , regexTest "error5.txt" regex True
+    ]
+    where
+        regex = errorMessageRegexes !! 0
+
+testRegexTwo :: TestTree
+testRegexTwo = testGroup "Regex Two" [
+        regexTest "error1.txt" regex False
+        , regexTest "error2.txt" regex False
+        , regexTest "error3.txt" regex True
+        , regexTest "error4.txt" regex False
+        , regexTest "error5.txt" regex False
+    ]
+    where
+        regex = errorMessageRegexes !! 1
+
+-- test ghc-9.2 error message regex
+testRegex921One :: TestTree
+testRegex921One = testGroup "Regex One" [
+        regexTest "ghc921-error1.txt" regex True
+        , regexTest "ghc921-error2.txt" regex True
+        , regexTest "ghc921-error3.txt" regex True
+    ]
+    where
+        regex = errorMessageRegexes !! 2
+
+testDataDir :: FilePath
+testDataDir = "test" </> "testdata"
+
+goldenChangeSignature :: FilePath -> (TextDocumentIdentifier -> Session ()) -> TestTree
+goldenChangeSignature fp = goldenWithHaskellDoc changeTypeSignaturePlugin (fp <> " (golden)") testDataDir fp "expected" "hs"
+
+codeActionTest :: FilePath -> Int -> Int -> TestTree
+codeActionTest fp line col = goldenChangeSignature fp $ \doc -> do
+    void $ waitForDiagnostics  -- code actions are triggered from Diagnostics
+    void $ waitForAllProgressDone  -- apparently some tests need this to get the CodeAction to show up
+    actions <- getCodeActions doc (pointRange line col)
+    foundActions <- findChangeTypeActions actions
+    liftIO $ length foundActions @?= 1
+    executeCodeAction (head foundActions)
+
+codeActionProperties :: TestName -> [(Int, Int)] -> ([CodeAction] -> Session ()) -> TestTree
+codeActionProperties fp locs assertions = testCase fp $ do
+    runSessionWithServer changeTypeSignaturePlugin testDataDir $ do
+        openDoc (fp <.> ".hs") "haskell" >>= codeActionsFromLocs >>= findChangeTypeActions >>= assertions
+    where
+        codeActionsFromLocs doc = concat <$> mapM (getCodeActions doc . uncurry pointRange) locs
+
+findChangeTypeActions :: [Command |? CodeAction] -> Session [CodeAction]
+findChangeTypeActions = pure . filter isChangeTypeAction . rights . map toEither
+    where
+        isChangeTypeAction CodeAction{_kind} = case _kind of
+          Nothing -> False
+          Just kind -> case kind of
+            "quickfix.changeSignature" -> True
+            _                          -> False
+
+
+regexTest :: FilePath -> Text -> Bool -> TestTree
+regexTest fp regex shouldPass = testCase fp $ do
+    msg <- TIO.readFile (testDataDir </> fp)
+    case (msg =~ regex  :: (Text, Text, Text, [Text]), shouldPass) of
+        ((_, _, _, [_, _, _, _]), True) -> pure ()
+        ((_, _, _, [_, _, _, _]), False) -> assertFailure $  "Unexpected match: " <> fp <> " with " <> T.unpack regex
+        (_, True) -> assertFailure $ "Failed to match: " <> fp <> " with " <> T.unpack regex
+        (_, False) -> pure ()
+
+pointRange :: Int -> Int -> Range
+pointRange
+  (subtract 1 -> fromIntegral -> line)
+  (subtract 1 -> fromIntegral -> col) =
+    Range (Position line col) (Position line $ col + 1)
diff --git a/test/testdata/TErrorGivenPartialSignature.hs b/test/testdata/TErrorGivenPartialSignature.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TErrorGivenPartialSignature.hs
@@ -0,0 +1,4 @@
+module ErrorGivenPartialSignature where
+
+partial :: Int -> Int
+partial x = init x
diff --git a/test/testdata/TExpectedActual.expected.hs b/test/testdata/TExpectedActual.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TExpectedActual.expected.hs
@@ -0,0 +1,6 @@
+module TExpectedActual where
+
+fullSig :: [Int] -> Int
+fullSig = go
+    where
+        go = head . reverse
diff --git a/test/testdata/TExpectedActual.hs b/test/testdata/TExpectedActual.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TExpectedActual.hs
@@ -0,0 +1,6 @@
+module TExpectedActual where
+
+fullSig :: Int -> Int
+fullSig = go
+    where
+        go = head . reverse
diff --git a/test/testdata/TLocalBinding.expected.hs b/test/testdata/TLocalBinding.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBinding.expected.hs
@@ -0,0 +1,8 @@
+module TLocalBinding where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: t0 a0 -> (a0 -> m0 b0) -> m0 (t0 b0)
+              test = forM
+          in x + 1
diff --git a/test/testdata/TLocalBinding.hs b/test/testdata/TLocalBinding.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBinding.hs
@@ -0,0 +1,8 @@
+module TLocalBinding where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: Int -> Int
+              test = forM
+          in x + 1
diff --git a/test/testdata/TLocalBindingShadow1.expected.hs b/test/testdata/TLocalBindingShadow1.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBindingShadow1.expected.hs
@@ -0,0 +1,11 @@
+module TLocalBindingShadow1 where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: Int -> Int
+              test = (+2)
+          in test x
+
+test :: [Double] -> (Double -> m0 b0) -> m0 [b0]
+test = forM
diff --git a/test/testdata/TLocalBindingShadow1.hs b/test/testdata/TLocalBindingShadow1.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBindingShadow1.hs
@@ -0,0 +1,11 @@
+module TLocalBindingShadow1 where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: Int -> Int
+              test = (+2)
+          in test x
+
+test :: [Double] -> Double
+test = forM
diff --git a/test/testdata/TLocalBindingShadow2.expected.hs b/test/testdata/TLocalBindingShadow2.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBindingShadow2.expected.hs
@@ -0,0 +1,11 @@
+module TLocalBindingShadow2 where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: t0 a0 -> (a0 -> m0 b0) -> m0 (t0 b0)
+              test = forM
+          in test x
+
+test :: String -> String
+test = reverse
diff --git a/test/testdata/TLocalBindingShadow2.hs b/test/testdata/TLocalBindingShadow2.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TLocalBindingShadow2.hs
@@ -0,0 +1,11 @@
+module TLocalBindingShadow2 where
+
+import Control.Monad (forM)
+
+local :: Int -> Int
+local x = let test :: Int -> Int
+              test = forM
+          in test x
+
+test :: String -> String
+test = reverse
diff --git a/test/testdata/TRigidType.expected.hs b/test/testdata/TRigidType.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TRigidType.expected.hs
@@ -0,0 +1,6 @@
+module TRigidType where
+
+test :: [[Int]] -> Int
+test = go . head . reverse
+    where
+        go = head . reverse
diff --git a/test/testdata/TRigidType.hs b/test/testdata/TRigidType.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/TRigidType.hs
@@ -0,0 +1,6 @@
+module TRigidType where
+
+test :: a -> Int
+test = go . head . reverse
+    where
+        go = head . reverse
diff --git a/test/testdata/hie.yaml b/test/testdata/hie.yaml
new file mode 100644
--- /dev/null
+++ b/test/testdata/hie.yaml
@@ -0,0 +1,12 @@
+cradle:
+  direct:
+    arguments:
+      - -i
+      - -i.
+      - TExpectedActual
+      - TRigidType
+      - TErrorGivenPartialSignature
+      - TLocalBinding
+      - TLocalBindingShadow1
+      - TLocalBindingShadow2
+      - -Wall
