fix(build): invalidate cores on SDK module edits

build.zig

@@ -844,6 +844,10 @@ pub fn build(b: *std.Build) void {
         .{ .path = "build/app.zig", .pattern = "const contract = stabilizeGeneratedFile(b, contract_raw, \"core.contract.json\", build_trace);" },
         .{ .path = "build/app.zig", .pattern = "break :services_contract stabilizeGeneratedFile(b, raw, \"services.contract.json\", build_trace);" },
         .{ .path = "build/app.zig", .pattern = "addAppCoreTsDirInputs(b, stage_run, appPath(b, app_root, \"src\"));" },
+        .{ .path = "build/app.zig", .pattern = "addStagedCoreSdkInputs(b, dep.builder, stage_run);" },
+        .{ .path = "build/app.zig", .pattern = "for ([_][]const u8{ \"text.ts\", \"events.ts\" }) |source|" },
+        .{ .path = "build.zig", .pattern = "app_build.addStagedCoreSdkInputs(b, b, stage_run);" },
+        .{ .path = "packages/core/scripts/stage_external_core.mjs", .pattern = "for (const sdkFile of [\"text.ts\", \"events.ts\"])" },
         .{ .path = "build/app.zig", .pattern = "if (std.mem.startsWith(u8, normalized, \"services/\")) continue;" },
         .{ .path = "tools/corewire/emit_service.zig", .pattern = "native-sdk.services.abi.v3" },
         .{ .path = "tools/corewire/emit_service.zig", .pattern = "implementation-only fingerprint" },
@@ -4042,6 +4046,7 @@ fn externalCoreFixtureModule(
         stage_run.addFileArg(client);
     }
     tsCoreAddCoreDirInputs(b, stage_run, std.fs.path.dirname(spec.entry) orelse ".");
+    app_build.addStagedCoreSdkInputs(b, b, stage_run);
     stage_run.addArg("--out");
     const stage_dir = stage_run.addOutputDirectoryArg("stage");
 

build/app.zig

@@ -1112,13 +1112,14 @@ fn tsCoreStage(
         stage_run.addFileArg(client);
     }
     // `addDirectoryArg` orders the stager after a generated directory but
-    // does not hash a source directory's recursively discovered contents.
-    // The old graph accidentally got core-source invalidation from changing
-    // producer cache paths. Now that generated ABI files are stabilized by
-    // content, state the author's actual core compile inputs explicitly.
-    // Services are excluded because stage_external_core.mjs excludes them;
-    // their implementation class has its own compile lane.
+    // does not hash a source directory's discovered contents. The old graph
+    // accidentally got core-source invalidation from changing producer cache
+    // paths. Now that generated ABI files are stabilized by content, state
+    // every source the stager copies explicitly: authored core files plus the
+    // two SDK implementation modules. Services are excluded because they have
+    // their own compile lane.
     addAppCoreTsDirInputs(b, stage_run, appPath(b, app_root, "src"));
+    addStagedCoreSdkInputs(b, dep.builder, stage_run);
     stage_run.addArg("--out");
     const stage_dir = stage_run.addOutputDirectoryArg("stage");
 
@@ -1320,6 +1321,18 @@ fn addAppCoreTsDirInputs(b: *std.Build, stage: *std.Build.Step.Run, src_path: []
     }
 }
 
+/// Declare the SDK implementation modules copied by
+/// stage_external_core.mjs. A directory LazyPath supplies ordering only for
+/// this source tree; these file inputs make implementation-only SDK edits
+/// invalidate the staged tree and compiled core archive even when the public
+/// contract remains byte-identical. Public for the repository fixture graph,
+/// which exercises the same compiler boundary as app builds.
+pub fn addStagedCoreSdkInputs(b: *std.Build, sdk_builder: *std.Build, stage: *std.Build.Step.Run) void {
+    for ([_][]const u8{ "text.ts", "events.ts" }) |source| {
+        stage.addFileInput(sdk_builder.path(b.fmt("packages/core/sdk/{s}", .{source})));
+    }
+}
+
 fn appHasServiceFiles(b: *std.Build, app_root: []const u8) bool {
     const services_path = appPath(b, app_root, "src/services");
     var dir = b.build_root.handle.openDir(b.graph.io, services_path, .{ .iterate = true }) catch return false;