Refactor nix/lib.nix and cache hatter for iOS/watchOS

Changelog.md

@@ -1,22 +1,82 @@
 # Change log for hatter
 
-## Version 0.3.0 2026.04.19 
-We used advanced sciences and made hatter even better!
-
-Science was used to make the animations work!
+## Version 0.3.0 2026.04.19
 
+### Breaking changes
 
-Also we used science to get IOS to run and install !!!
+- `Column` and `Row` constructors now take `LayoutSettings` instead of
+  `[Widget]`.  Use the `column`, `row`, `scrollColumn`, `scrollRow`
+  smart constructors for the old behaviour.
+- `ScrollView` constructor removed.  Scrolling is now a property of
+  `Column`/`Row` via the `lsScrollable` field in `LayoutSettings`,
+  or use `scrollColumn`/`scrollRow`.
+- Container children are now wrapped in `LayoutItem` (with optional
+  `WidgetKey`) for key-based diffing.
+- `Easing`-based tween animations replaced with CSS-like keyframe
+  animations.  Use `linearAnimation`, `easeIn`, `easeOut`,
+  `easeInOut`, `andThen`, and `lerpStyle` for the new API.
+- Removed configurable `soName` from `mkAndroidLib`.
 
-We had some science left and use that to
-kill all bugs with pesticides.
+### Added
 
-very good.
+- `Hatter.Widget.Stack` — z-order overlay container (maps to
+  FrameLayout on Android, UIView overlay on iOS, ZStack on watchOS).
+  Includes `wsTouchPassthrough` style field for controlling touch
+  interception on overlay layers.
+- Smart constructors: `column`, `row`, `scrollColumn`, `scrollRow`,
+  `stack`, `item`, `keyedItem`.
+- `LayoutSettings`, `LayoutItem`, `WidgetKey` types for keyed
+  container children with key-based child matching in `diffContainer`.
+- Keyframe animation API: `linearAnimation`, `easeIn`, `easeOut`,
+  `easeInOut`, `andThen`, `lerpStyle` for composable CSS-like
+  animation sequences.
+- `requestRedraw` API (`Hatter.Render`) for triggering UI re-renders
+  from background threads.  Uses C pthread timer on Android
+  (non-threaded RTS safe) and platform-native dispatch elsewhere.
+- `tiAutoFocus` field on `TextInputConfig` — auto-focus on render
+  (deferred on Android via `View.post` for attachment safety).
+- `Hatter.DeviceInfo` — query device model, OS version, and screen
+  dimensions on all platforms.
+- Re-render UI automatically after `TextInput` value changes.
+- `hatter_hs_init` with `RtsConfig` for reliable RTS initialisation
+  on iOS/watchOS (fixes `hs_init` hang).
+- RTS heap limit (`-xr`) on iOS/watchOS real devices to avoid 1TB
+  `mmap` rejection.
+- Build hatter as a normal cross-compiled Haskell package via
+  `collect-deps.nix` / `cross-deps.nix`.
+- Share pre-compiled hatter objects across all Android ABI builds.
+- `-split-sections` + `--gc-sections` for smaller Android `.so` files.
+- Node ID reclamation via free stack on all platforms.
 
-I can make ask claudes to make a nice overview in here.
-but fuck that,
+### Fixed
 
-better to make u laugh traveler.
+- First-render animation bug: tweens now register from zero origin
+  on initial render, not only on re-render.
+- Animated widget toggle-back bug: animation config preserved when
+  toggling an `Animated` wrapper off then back on.
+- Key-based child diffing prevents cascading native view destruction
+  when inserting/removing children mid-list.
+- Index-based default keys replace content-based `inferKey`, avoiding
+  hash collisions for identical widgets.
+- `Styled` wrapper now reapplies style when the child widget changes
+  type (e.g. `Text` to `Button`).
+- Android `destroy_node` detaches view from parent before freeing JNI
+  refs (fixes orphaned native views).
+- ScrollView SIGABRT on Android when mixing `TextInput` with other
+  widgets — children now wrapped in inner `LinearLayout`.
+- Android `TextWatcher` re-entry crash prevented by guarding against
+  redundant `setText` calls.
+- In-place diff for `Text`/`Button` widgets preserves native IME
+  connection on Android.
+- armv7a OOM from duplicated `registerForeignExports` `.init_array`
+  entries.
+- iOS/watchOS cross-build: drop `deriving stock` on `WidgetKey`.
+- iOS `hs_init` hang resolved via `hatter_hs_init` with explicit
+  `RtsConfig` and null-terminated argv.
+- Swift type inference errors on Xcode 16.4.
+- `os_log` `CVarArg` conformance on iOS — use `String(describing:)`
+  for pointer values.
+- GNU `libffi` built from source for static iOS/watchOS bundling.
 
 ## Version 0.2.0
 

hatter.cabal

@@ -119,7 +119,8 @@ library
       containers < 1,
       bytestring < 1,
       transformers < 0.7,
-      time
+      time,
+      unwitch >= 3.0.0 && < 4
   c-sources:
       cbits/android_stubs.c
       cbits/platform_log.c
@@ -191,7 +192,8 @@ executable redraw-demo
       test
   build-depends:
       hatter,
-      text
+      text,
+      unwitch >= 3.0.0 && < 4
 
 executable confetti-repro-demo
   import: common-options
@@ -250,4 +252,5 @@ test-suite unit
       text,
       bytestring,
       directory,
-      filepath
+      filepath,
+      unwitch >= 3.0.0 && < 4

nix/cross-deps.nix

@@ -228,10 +228,18 @@ WRAPPER
         });
     } else {};
 
+  unwitchOverride = self: super: {
+    unwitch = self.callCabal2nix "unwitch" (builtins.fetchTarball {
+      url = "https://github.com/jappeace/unwitch/archive/2759bdd153f293e0e6524d0170e861e51302caa4.tar.gz";
+      sha256 = "sha256:BGxZ1CQGIYP/gg/J9jua2/wSEH4qq7bW91qooNELUlI=";
+    }) {};
+  };
+
   defaultOverrides =
     let
       common = pkgs.lib.composeManyExtensions [
         vectorOverride
+        unwitchOverride
         thPackageDbOverride
         thIservOverride
         hatterOverride
@@ -284,9 +292,13 @@ WRAPPER
   # so its .a and .conf are available for linking.
   hatterDep = if hatterSrc != null then [ crossHaskellPkgs.hatter ] else [];
 
+  # Hatter's own non-boot dependencies — must be collected so hatter's
+  # .conf can resolve them (collect-deps doesn't follow propagatedBuildInputs).
+  hatterOwnDeps = [ crossHaskellPkgs.unwitch ];
+
 in import ./collect-deps.nix {
   inherit pkgs ghc ghcPkgCmd;
-  deps = resolvedDeps ++ hatterDep;
+  deps = resolvedDeps ++ hatterDep ++ hatterOwnDeps;
   mainLibPnames = if hatterSrc != null then [ "hatter" ] else [];
   iservProxy = iservWrapper;
 }

nix/hpkgs.nix

@@ -9,5 +9,9 @@ pkgs.haskellPackages.override {
     # NB this is a bit silly because nix files are now considered for the build
     # bigger projects should consider putting haskell stuff in a subfolder
     hatter-project = hnew.callCabal2nix "hatter" ../. { };
+    unwitch = hnew.callCabal2nix "unwitch" (builtins.fetchTarball {
+      url = "https://github.com/jappeace/unwitch/archive/2759bdd153f293e0e6524d0170e861e51302caa4.tar.gz";
+      sha256 = "sha256:BGxZ1CQGIYP/gg/J9jua2/wSEH4qq7bW91qooNELUlI=";
+    }) {};
   };
 }

nix/ios-deps.nix

@@ -14,12 +14,39 @@
 , consumerCabalFile ? null
 , consumerCabal2Nix ? null
 , hpkgs ? (_: _: {})       # consumer haskellPackages overrides
+, hatterSrc ? null          # hatter source tree (builds hatter as a normal dep)
 }:
 let
   pkgs = import sources.nixpkgs {};
 
+  unwitchOverride = self: super: {
+    unwitch = self.callCabal2nix "unwitch" (builtins.fetchTarball {
+      url = "https://github.com/jappeace/unwitch/archive/2759bdd153f293e0e6524d0170e861e51302caa4.tar.gz";
+      sha256 = "sha256:BGxZ1CQGIYP/gg/J9jua2/wSEH4qq7bW91qooNELUlI=";
+    }) {};
+  };
+
+  # Build hatter as a regular haskellPackages derivation from local source.
+  # Executables and tests are stripped to avoid pulling in test-framework deps.
+  hatterOverride = self: super:
+    if hatterSrc != null then {
+      hatter = pkgs.haskell.lib.overrideCabal
+        (self.callCabal2nix "hatter" hatterSrc {})
+        (old: {
+          postPatch = (old.postPatch or "") + ''
+            sed -i '/^executable /,$d' hatter.cabal
+            sed -i '/^test-suite /,$d' hatter.cabal
+          '';
+          doCheck = false;
+        });
+    } else {};
+
   nativeHaskellPkgs = pkgs.haskellPackages.override {
-    overrides = hpkgs;
+    overrides = pkgs.lib.composeManyExtensions [
+      unwitchOverride
+      hatterOverride
+      hpkgs
+    ];
   };
 
   ghc = nativeHaskellPkgs.ghc;
@@ -30,7 +57,15 @@ let
     haskellPkgs = nativeHaskellPkgs;
   };
 
+  # When hatterSrc is provided, add the hatter package to the collected deps
+  # so its .a and .conf are available for linking.
+  hatterDep = if hatterSrc != null then [ nativeHaskellPkgs.hatter ] else [];
+
+  # Hatter's own non-boot dependencies — always included so mkIOSLib's
+  # raw GHC invocation can find them even without a consumer cabal file.
+  hatterOwnDeps = [ nativeHaskellPkgs.unwitch ];
+
 in import ./collect-deps.nix {
   inherit pkgs ghc ghcPkgCmd;
-  deps = resolvedDeps;
+  deps = resolvedDeps ++ hatterDep ++ hatterOwnDeps;
 }

nix/ios.nix

@@ -14,6 +14,7 @@ let
   lib = import ./lib.nix { inherit sources; };
   iosDeps = import ./ios-deps.nix {
     inherit sources consumerCabalFile consumerCabal2Nix hpkgs;
+    hatterSrc = ../.;
   };
 in
 lib.mkIOSLib {