bundling: Android APK pipeline moved into sx; android.sx state-on-plat

Week 7 of /Users/agra/.claude/plans/lets-plan-to-move-splendid-pumpkin.md
plus the android.sx refactor + three sx-compiler fixes hit along the way
to get chess on Pixel 7 Pro responding to touch end-to-end.

library/modules/platform/bundle.sx now covers the Android APK shape
alongside macOS / iOS-sim / iOS-device. `android_bundle_main` discovers
the SDK ($ANDROID_HOME / $ANDROID_SDK_ROOT / $HOME/Library/Android/sdk),
picks the highest-versioned build-tools + platforms via
`process.run("ls .. | sort -V | tail -1")`, stages
`<apk>.stage/lib/arm64-v8a/<libfoo.so>`, synthesizes
AndroidManifest.xml (NativeActivity vs `#jni_main` Activity branch),
writes each `#jni_main` decl's Java source under
`<stage>/java/<pkg>/<Cls>.java`, runs javac --release 11 + d8 to
produce classes.dex, aapt2-links the unaligned APK, appends lib/ +
classes.dex + each registered asset tree via zip, zipalign + ensure
debug keystore via keytool + apksigner sign.

Compiler-side accessors (src/ir/compiler_hooks.zig + library/modules/compiler.sx):
- is_android predicate.
- set_manifest_path / manifest_path + set_keystore_path / keystore_path.
- jni_main_count / jni_main_foreign_path_at(i) /
  jni_main_java_source_at(i) surface the `#jni_main` emissions that
  the Zig createApk previously consumed directly.
- main.zig wires manifest_path, keystore_path, and the per-decl
  (foreign_path, java_source) parallel slices into BuildConfig before
  invoking the post-link callback.

CLI `--apk <path>` keeps working as a transitional alias: it now feeds
bundle_path so the existing auto-`post_link_module = "platform.bundle"`
shim fires the same way as `--bundle`. main.zig no longer calls
target.createApk directly.

Deletions in src/target.zig: createApk, compileJniMainSources,
buildJniMainManifest, buildAndroidManifest, ensureDebugKeystore,
libNameFromSoBasename, plus helpers splitForeignPath / discoverJavac /
discoverAndroidSdk / findHighestSubdir / runProcess / runProcessIn
(~400 lines). git grep returns only the obituary comment.

library/modules/platform/android.sx refactor (chess Android dependency):
- Module-level globals retired (g_app_window, g_egl_*, g_viewport_*,
  g_dpi_scale, g_should_stop, g_render_thread*, g_user_main_fn,
  g_touch_*) → AndroidPlatform struct fields.
- All sx_android_* helpers take `plat: *AndroidPlatform` as first arg.
  Render thread receives plat via pthread_create's arg.
- New `logical_w: f32 = 0.0` field. Consumers set it before init() to
  define the design width in points; `recompute_scale` derives
  `dpi_scale = pixel_w / logical_w` (or 1.0 if unset). Called on
  init / set_viewport / egl_init. drain_touches divides incoming
  physical pixel coords by dpi_scale so chess sees logical-space
  positions matching its layout. Touch lands on the right squares.

Three sx-compiler bugs hit + fixed along the way:

1. Top-level `inline if OS == .X { decls }` body decls were silently
   dropped because scanDecls/lowerDecls had no .if_expr arm. New
   `flattenComptimeConditionals` pre-pass in src/imports.zig
   (threaded via ComptimeContext from core.zig) hoists matching arms
   recursively. Regression at examples/124-inline-if-hoist-toplevel.sx.

2. Parser rejected `#import` / `#framework` inside inline-if bodies
   because parseStmt in src/parser.zig only had arms for `#insert`.
   Added the missing arms. Regression at
   examples/123-inline-if-import-in-body.sx (landed earlier).

3. JNI `Call<T>Method` switches in src/ir/emit_llvm.zig (instance /
   nonvirtual / static) were missing `.f32` rows — jfloat returns
   (e.g. MotionEvent.getX/getY) fell into the silent-undef else arm.
   Chess's sx_android_push_touch(plat, getAction(), getX(), getY())
   delivered garbage f32 coords to the touch ring, so taps landed
   nowhere recognisable. Added `.f32 => Jni.Call{Static,Nonvirtual,}FloatMethod`
   rows to all three switches; lifted unsupported-type detection
   from emit_llvm into lowerForeignMethodCall with proper
   source-spanned diagnostics (`isJniReturnTypeSupported`). Regressions
   at examples/ffi-jni-call-10-jfloat-return.sx,
   examples/ffi-jni-class-09-multi-float-args.sx,
   examples/ffi-jni-call-11-unsupported-return-diag.sx.

Stale-snapshot drift in tests/expected/ffi-objc-call-03-selector-sharing.ir
and ffi-objc-call-06-sret-return.ir picks up the new BuildOptions
accessor extern decls (is_android, set_manifest_path,
set_keystore_path, jni_main_count, jni_main_foreign_path_at,
jni_main_java_source_at). Verified diff is dead-decl-only.

Chess on Pixel 7 Pro: tap on e2 white pawn -> yellow selection +
green dots on legal e3/e4 targets; tap on e4 -> board updates with
1. e4, "Black to move" + "1. e4" in info panel.

zig build && zig build test && bash tests/run_examples.sh -> 145/145
green. bash tests/cross_compile.sh -> 7/7 green.

src/core.zig

@@ -38,8 +38,10 @@ pub const Compilation = struct {
     /// AST sources in `collectCImportSources`.
     lowering_extra_c_sources: std.ArrayList(c_import.CImportInfo) = .empty,
     /// `#jni_main #jni_class("...")` declarations whose Java sources were
-    /// rendered during lowering. Read by the APK pipeline (`createApk`)
-    /// to write `.java` files + run `javac` + `d8` + bundle `classes.dex`.
+    /// rendered during lowering. Surfaced to the sx Android bundler
+    /// (`library/modules/platform/bundle.sx`) via `BuildConfig.jni_main_*`
+    /// in `compiler_hooks.zig`; the bundler writes `.java` files + runs
+    /// `javac` + `d8` + bundles `classes.dex` into the APK.
     lowering_jni_main_decls: std.ArrayList(JniMainEmission) = .empty,
 
     pub fn init(allocator: std.mem.Allocator, io: std.Io, file_path: []const u8, source: [:0]const u8, target_config: TargetConfig, stdlib_paths: []const []const u8) Compilation {
@@ -72,6 +74,18 @@ pub const Compilation = struct {
         self.root = p.parse() catch return error.CompileError;
     }
 
+    /// Derive the comptime evaluation context (OS / ARCH / POINTER_SIZE
+    /// values) from the build target. Used by `imports.resolveImports`
+    /// to hoist top-level `inline if OS == .X { ... }` body decls
+    /// before resolution; mirrors `injectComptimeConstants` in lowering.
+    fn comptimeContext(self: *const Compilation) imports.ComptimeContext {
+        const tc = self.target_config;
+        const os: []const u8 = if (tc.isWasm()) "wasm" else if (tc.isWindows()) "windows" else if (tc.isAndroid()) "android" else if (tc.isLinux()) "linux" else if (tc.isIOS()) "ios" else if (tc.isMacOS()) "macos" else "unknown";
+        const arch: []const u8 = if (tc.isWasm32()) "wasm32" else if (tc.isWasm64()) "wasm64" else if (tc.isAarch64()) "aarch64" else if (tc.isX86_64()) "x86_64" else "unknown";
+        const ptr_size: i64 = if (tc.isWasm32()) 4 else 8;
+        return .{ .os = os, .arch = arch, .pointer_size = ptr_size };
+    }
+
     pub fn resolveImports(self: *Compilation) !void {
         const root = self.root orelse return error.CompileError;
         var chain = std.StringHashMap(void).init(self.allocator);
@@ -89,6 +103,7 @@ pub const Compilation = struct {
             &self.diagnostics,
             self.stdlib_paths,
             &self.import_graph,
+            self.comptimeContext(),
         ) catch return error.CompileError;
 
         // Preserve per-module visibility scopes for C import access checking
@@ -166,7 +181,13 @@ pub const Compilation = struct {
         defer interp.deinit();
         if (self.ir_emitter) |*e| interp.build_config = &e.build_config;
         ir.Interpreter.last_bail_op = null;
-        return try interp.call(id, args);
+        ir.Interpreter.last_bail_builtin = null;
+        const result = interp.call(id, args) catch |err| {
+            if (interp.output.items.len > 0) std.debug.print("{s}", .{interp.output.items});
+            return err;
+        };
+        if (interp.output.items.len > 0) std.debug.print("{s}", .{interp.output.items});
+        return result;
     }
 
     /// Get link flags accumulated from #run build blocks.