diff --git a/common/web/keyboard-processor/build.sh b/common/web/keyboard-processor/build.sh
index 3921063bb9..964370c2fb 100755
--- a/common/web/keyboard-processor/build.sh
+++ b/common/web/keyboard-processor/build.sh
@@ -17,6 +17,7 @@ BUNDLE_CMD="node ${KEYMAN_ROOT}/common/web/es-bundling/build/common-bundle.mjs"
 builder_describe \
   "Compiles the web-oriented utility function module." \
   "@/web/src/tools/testing/recorder-core  test" \
+  "@/web/src/engine/js-processor test" \
   "@/common/web/keyman-version" \
   "@/common/web/es-bundling" \
   "@/common/web/types" \
@@ -64,10 +65,10 @@ function do_build() {
     --platform node
 
   # Tests
-  builder_echo "Bundle tests"
-  ${BUNDLE_CMD} "${KEYMAN_ROOT}/common/web/keyboard-processor/build/tests/dom/cases/domKeyboardLoader.spec.js" \
-    --out       "${KEYMAN_ROOT}/common/web/keyboard-processor/build/tests/dom/domKeyboardLoader.spec.mjs" \
-    --format   esm
+  # builder_echo "Bundle tests"
+  # ${BUNDLE_CMD} "${KEYMAN_ROOT}/common/web/keyboard-processor/build/tests/dom/cases/domKeyboardLoader.spec.js" \
+  #   --out       "${KEYMAN_ROOT}/common/web/keyboard-processor/build/tests/dom/domKeyboardLoader.spec.mjs" \
+  #   --format   esm
 
   # Declaration bundling.
   builder_echo "Declaration bundling"
@@ -92,4 +93,4 @@ function do_test() {
 builder_run_action configure  do_configure
 builder_run_action clean      rm -rf ./build
 builder_run_action build      do_build
-builder_run_action test       do_test
+# builder_run_action test       do_test
diff --git a/common/web/keyboard-processor/src/index.ts b/common/web/keyboard-processor/src/index.ts
index f800691cfa..d9d0b2137f 100644
--- a/common/web/keyboard-processor/src/index.ts
+++ b/common/web/keyboard-processor/src/index.ts
@@ -29,18 +29,12 @@ export * from "./text/codes.js";
 export * from "./text/deadkeys.js";
 export { default as DefaultRules } from "./text/defaultRules.js";
 export * from "./text/defaultRules.js";
-export { default as KeyboardInterface } from "./text/kbdInterface.js";
-export * from "./text/kbdInterface.js";
-export { default as KeyboardProcessor } from "./text/keyboardProcessor.js";
-export * from "./text/keyboardProcessor.js";
 export { default as KeyEvent } from "./text/keyEvent.js";
 export * from "./text/keyEvent.js";
 export { default as KeyMapping } from "./text/keyMapping.js";
 export { default as OutputTarget } from "./text/outputTarget.js";
 export * from "./text/outputTarget.js";
-export { default as RuleBehavior } from "./text/ruleBehavior.js";
 export * from "./text/stringDivergence.js";
-export * from "./text/systemStores.js";
 
 export * from "@keymanapp/web-utils";
 
@@ -48,4 +42,4 @@ export * from "@keymanapp/web-utils";
 
 // Without the line below... OutputTarget would likely be aliased there, as it's
 // the last `export { default as _ }` => `export * from` pairing seen above.
-export default undefined;
\ No newline at end of file
+export default undefined;
diff --git a/common/web/keyboard-processor/src/keyboards/keyboard.ts b/common/web/keyboard-processor/src/keyboards/keyboard.ts
index 5312d825a6..d791d6ea75 100644
--- a/common/web/keyboard-processor/src/keyboards/keyboard.ts
+++ b/common/web/keyboard-processor/src/keyboards/keyboard.ts
@@ -6,11 +6,11 @@ import type OutputTarget from "../text/outputTarget.js";
 import { ModifierKeyConstants, TouchLayout } from "@keymanapp/common-types";
 type TouchLayoutSpec = TouchLayout.TouchLayoutPlatform & { isDefault?: boolean};
 
-import type { ComplexKeyboardStore } from "../text/kbdInterface.js";
-
 import { Version, DeviceSpec } from "@keymanapp/web-utils";
 import StateKeyMap from "./stateKeyMap.js";
 
+type ComplexKeyboardStore = ( string | { t: 'd', d: number } | { ['t']: 'b' })[];
+
 /**
  * Stores preprocessed properties of a keyboard for quick retrieval later.
  */
diff --git a/common/web/keyboard-processor/src/keyboards/keyboardHarness.ts b/common/web/keyboard-processor/src/keyboards/keyboardHarness.ts
index 671c8fefd7..109d209067 100644
--- a/common/web/keyboard-processor/src/keyboards/keyboardHarness.ts
+++ b/common/web/keyboard-processor/src/keyboards/keyboardHarness.ts
@@ -1,5 +1,6 @@
 import Keyboard from "./keyboard.js";
 import Codes from "../text/codes.js";
+import { DeviceSpec } from '@keymanapp/web-utils';
 
 /**
  * Defines members of the top-level `keyman` global object necessary to guarantee
@@ -40,6 +41,8 @@ export const MinimalKeymanGlobal: KeyboardKeymanGlobal = {
 export class KeyboardHarness {
   public readonly _jsGlobal: any;
   public readonly keymanGlobal: KeyboardKeymanGlobal;
+  activeDevice: DeviceSpec;
+
 
   /**
    * Constructs and configures a harness for receiving dynamically-loaded Keyman keyboards.
diff --git a/common/web/keyboard-processor/src/text/defaultRules.ts b/common/web/keyboard-processor/src/text/defaultRules.ts
index 931eb5200b..94acb02688 100644
--- a/common/web/keyboard-processor/src/text/defaultRules.ts
+++ b/common/web/keyboard-processor/src/text/defaultRules.ts
@@ -1,32 +1,28 @@
-// TODO:  Move to separate folder:  'codes'
-// We should start splitting off code needed by keyboards even without a KeyboardProcessor active.
-// There's an upcoming `/common/web/types` package that 'codes' and 'keyboards' may fit well within.
+/*
+ * Keyman is copyright (C) SIL International. MIT License.
+ *
+ * Implementation of default rules
+ */
 
-import { ModifierKeyConstants} from '@keymanapp/common-types';
-import Codes from "./codes.js";
-import type KeyEvent from "./keyEvent.js";
-import type OutputTarget from "./outputTarget.js";
-
-// The only members referenced are to produce warning and error logs.  A little abstraction
-// via an optional 'logger' interface can maintain it while facilitating a the split alluded
-// to above.
-//
-// Alternatively, we could just... not take in the parameter at all, which'd also facilitate
-// the future modularization effort.
-import RuleBehavior from "./ruleBehavior.js";
+import { ModifierKeyConstants } from '@keymanapp/common-types';
+import Codes from './codes.js';
+import type KeyEvent from './keyEvent.js';
+import type OutputTarget  from './outputTarget.js';
 
 export enum EmulationKeystrokes {
   Enter = '\n',
   Backspace = '\b'
 }
 
+export class LogMessages {
+  errorLog?: string;
+  warningLog?: string;
+}
+
 /**
  * Defines a collection of static library functions that define KeymanWeb's default (implied) keyboard rule behaviors.
  */
 export default class DefaultRules {
-  public constructor() {
-  }
-
   codeForEvent(Lkc: KeyEvent) {
     return Codes.keyCodes[Lkc.kName] || Lkc.Lcode;;
   }
@@ -35,7 +31,7 @@ export default class DefaultRules {
    * Serves as a default keycode lookup table.  This may be referenced safely by mnemonic handling without fear of side-effects.
    * Also used by Processor.defaultRuleBehavior to generate output after filtering for special cases.
    */
-  public forAny(Lkc: KeyEvent, isMnemonic: boolean, ruleBehavior?: RuleBehavior) {
+  public forAny(Lkc: KeyEvent, isMnemonic: boolean, logMessages?: LogMessages): string {
     var char = '';
 
     // A pretty simple table of lookups, corresponding VERY closely to the original defaultKeyOutput.
@@ -43,9 +39,9 @@ export default class DefaultRules {
       return char;
     } else if(!isMnemonic && ((char = this.forNumpadKeys(Lkc)) != null)) {
       return char;
-    } else if((char = this.forUnicodeKeynames(Lkc, ruleBehavior)) != null) {
+    } else if((char = this.forUnicodeKeynames(Lkc, logMessages)) != null) {
       return char;
-    } else if((char = this.forBaseKeys(Lkc, ruleBehavior)) != null) {
+    } else if((char = this.forBaseKeys(Lkc, logMessages)) != null) {
       return char;
     } else {
       // // For headless and embeddded, we may well allow '\t'.  It's DOM mode that has other uses.
@@ -152,7 +148,7 @@ export default class DefaultRules {
 
   // Test for fall back to U_xxxxxx key id
   // For this first test, we ignore the keyCode and use the keyName
-  public forUnicodeKeynames(Lkc: KeyEvent, ruleBehavior?: RuleBehavior) {
+  public forUnicodeKeynames(Lkc: KeyEvent, logMessages?: LogMessages) {
     const keyName = Lkc.kName;
 
     // Test for fall back to U_xxxxxx key id
@@ -169,8 +165,8 @@ export default class DefaultRules {
         // Code points [U_0000 - U_001F] and [U_0080 - U_009F] refer to Unicode C0 and C1 control codes.
         // Check the codePoint number and do not allow output of these codes via U_xxxxxx shortcuts.
         // Also handles invalid identifiers (e.g. `U_ghij`) for which parseInt returns NaN
-        if(ruleBehavior) {
-          ruleBehavior.errorLog = ("Suppressing Unicode control code in " + keyName);
+        if(logMessages) {
+          logMessages.errorLog = ("Suppressing Unicode control code in " + keyName);
         }
         // We'll attempt to add valid chars
         continue;
@@ -185,17 +181,17 @@ export default class DefaultRules {
 
   // Test for otherwise unimplemented keys on the the base default & shift layers.
   // Those keys must be blocked by keyboard rules if intentionally unimplemented; otherwise, this function will trigger.
-  public forBaseKeys(Lkc: KeyEvent, ruleBehavior?: RuleBehavior) {
+  public forBaseKeys(Lkc: KeyEvent, logMessages?: LogMessages) {
     let n = Lkc.Lcode;
     let keyShiftState = Lkc.Lmodifiers;
 
     // check if exact match to SHIFT's code.  Only the 'default' and 'shift' layers should have default key outputs.
     // TODO:  Extend to allow AltGr as well - better mnemonic support.
-    if(keyShiftState == ModifierKeyConstants.K_SHIFTFLAG) {
+    if (keyShiftState == ModifierKeyConstants.K_SHIFTFLAG) {
       keyShiftState = 1;
     } else if(keyShiftState != 0) {
-      if(ruleBehavior) {
-        ruleBehavior.warningLog = "KMW only defines default key output for the 'default' and 'shift' layers!";
+      if(logMessages) {
+        logMessages.warningLog = "KMW only defines default key output for the 'default' and 'shift' layers!";
       }
       return null;
     }
@@ -216,8 +212,8 @@ export default class DefaultRules {
         return keyShiftState ? '|' : '\\';
       }
     } catch (e) {
-      if(ruleBehavior) {
-        ruleBehavior.errorLog = "Error detected with default mapping for key:  code = " + n + ", shift state = " + (keyShiftState == 1 ? 'shift' : 'default');
+      if(logMessages) {
+        logMessages.errorLog = "Error detected with default mapping for key:  code = " + n + ", shift state = " + (keyShiftState == 1 ? 'shift' : 'default');
       }
     }
 
diff --git a/common/web/keyboard-processor/src/text/keyEvent.ts b/common/web/keyboard-processor/src/text/keyEvent.ts
index a38992a3a1..7d6483d0e9 100644
--- a/common/web/keyboard-processor/src/text/keyEvent.ts
+++ b/common/web/keyboard-processor/src/text/keyEvent.ts
@@ -10,12 +10,12 @@ import type Keyboard from "../keyboards/keyboard.js";
 import { type DeviceSpec } from "@keymanapp/web-utils";
 
 import Codes from './codes.js';
-import DefaultRules from './defaultRules.js';
+import DefaultRules from "./defaultRules.js";
 import { ActiveKeyBase } from "../index.js";
 
 // Represents a probability distribution over a keyboard's keys.
 // Defined here to avoid compilation issues.
-export type KeyDistribution = {keySpec: ActiveKeyBase, p: number}[];
+export type KeyDistribution = { keySpec: ActiveKeyBase, p: number }[];
 
 /**
  * A simple instance of the standard 'default rules' for keystroke processing from the
@@ -188,4 +188,4 @@ export default class KeyEvent implements KeyEventSpec {
       }
     }
   }
-};
\ No newline at end of file
+};
diff --git a/common/web/keyboard-processor/tests/dom/readme.md b/common/web/keyboard-processor/tests/dom/readme.md
deleted file mode 100644
index 153b7f4a1e..0000000000
--- a/common/web/keyboard-processor/tests/dom/readme.md
+++ /dev/null
@@ -1,5 +0,0 @@
-Automated tests in this subfolder and its children are designed to facilitate simple, browser-independent
-unit tests that are DOM-reliant.
-
-Tests for anything that may reasonably vary depending upon the browser used to run the code should go under
-the "integrated" folder instead.
\ No newline at end of file
diff --git a/common/web/keyboard-processor/tests/dom/web-test-runner.CI.config.mjs b/common/web/keyboard-processor/tests/dom/web-test-runner.CI.config.mjs
deleted file mode 100644
index d18a8a9cb0..0000000000
--- a/common/web/keyboard-processor/tests/dom/web-test-runner.CI.config.mjs
+++ /dev/null
@@ -1,13 +0,0 @@
-// @ts-check
-import BASE_CONFIG from './web-test-runner.config.mjs';
-import teamcityReporter from '@keymanapp/common-test-resources/test-runner-TC-reporter.mjs';
-import { sessionStabilityReporter } from '@keymanapp/common-test-resources/test-runner-stability-reporter.mjs';
-
-/** @type {import('@web/test-runner').TestRunnerConfig} */
-export default {
-  ...BASE_CONFIG,
-  reporters: [
-    teamcityReporter(), /* custom-written, for CI-friendly reports */
-    sessionStabilityReporter({ciMode: true})
-  ]
-}
\ No newline at end of file
diff --git a/common/web/keyboard-processor/tests/dom/web-test-runner.config.mjs b/common/web/keyboard-processor/tests/dom/web-test-runner.config.mjs
deleted file mode 100644
index 76651182ac..0000000000
--- a/common/web/keyboard-processor/tests/dom/web-test-runner.config.mjs
+++ /dev/null
@@ -1,62 +0,0 @@
-// @ts-check
-import { devices, playwrightLauncher } from '@web/test-runner-playwright';
-import { esbuildPlugin } from '@web/dev-server-esbuild';
-import { defaultReporter, summaryReporter } from '@web/test-runner';
-import { LauncherWrapper, sessionStabilityReporter } from '@keymanapp/common-test-resources/test-runner-stability-reporter.mjs';
-import { importMapsPlugin } from '@web/dev-server-import-maps';
-import { dirname, resolve } from 'path';
-import { fileURLToPath } from 'url';
-
-const dir = dirname(fileURLToPath(import.meta.url));
-const KEYMAN_ROOT = resolve(dir, '../../../../..');
-
-/** @type {import('@web/test-runner').TestRunnerConfig} */
-export default {
-  // debug: true,
-  browsers: [
-    new LauncherWrapper(playwrightLauncher({ product: 'chromium' })),
-    new LauncherWrapper(playwrightLauncher({ product: 'firefox' })),
-    new LauncherWrapper(playwrightLauncher({ product: 'webkit', concurrency: 1 })),
-  ],
-  concurrency: 10,
-  nodeResolve: true,
-  files: [
-    'build/tests/dom/**/*.spec.mjs'
-  ],
-  middleware: [
-    // Rewrites short-hand paths for test resources, making them fully relative to the repo root.
-    function rewriteResourcePath(context, next) {
-      if(context.url.startsWith('/resources/')) {
-        context.url = '/common/test' + context.url;
-      }
-
-      return next();
-    }
-  ],
-  plugins: [
-    esbuildPlugin({ts: true, target: 'auto'}),
-    importMapsPlugin({
-      inject: {
-        importMap: {
-          // Redirects `eventemitter3` imports to the bundled ESM library.  The standard import is an
-          // ESM wrapper around the CommonJS implementation, and WTR fails when it hits the CommonJS.
-          imports: {
-            'eventemitter3': '/node_modules/eventemitter3/dist/eventemitter3.esm.js'
-          }
-        }
-      }
-    })
-  ],
-  reporters: [
-    summaryReporter({}), /* local-dev mocha-style */
-    sessionStabilityReporter({}),
-    defaultReporter({})
-  ],
-  /*
-    Un-comment the next two lines for easy interactive debugging; it'll launch the
-    test page in your preferred browser.
-  */
-  // open: true,
-  // manual: true,
-  rootDir: KEYMAN_ROOT
-}
diff --git a/common/web/keyboard-processor/tests/tsconfig.json b/common/web/keyboard-processor/tests/tsconfig.json
deleted file mode 100644
index 0e978545b8..0000000000
--- a/common/web/keyboard-processor/tests/tsconfig.json
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "extends": "../tsconfig.json",
-  "compilerOptions": {
-    "baseUrl": "../",
-    "outDir": "../build/tests/",
-    "tsBuildInfoFile": "../build/tests/tsconfig.tsbuildinfo",
-    "rootDir": "./"
-  },
-  "include": [ "./dom/**/*.ts"],
-  "exclude": []
-}
diff --git a/common/web/keyboard-processor/tsconfig.all.json b/common/web/keyboard-processor/tsconfig.all.json
index dabb262d9c..79f10644d1 100644
--- a/common/web/keyboard-processor/tsconfig.all.json
+++ b/common/web/keyboard-processor/tsconfig.all.json
@@ -9,7 +9,6 @@
   "references": [
     { "path": "./src/keyboards/loaders/tsconfig.dom.json" },
     { "path": "./src/keyboards/loaders/tsconfig.node.json" },
-    { "path": "./tests/tsconfig.json" },
   ],
   // Actual main-body compilation is in tsconfig.json.  This config is just a wrapper
   // to trigger all three components at once.
diff --git a/web/README.md b/web/README.md
index 1249805165..775f303df5 100644
--- a/web/README.md
+++ b/web/README.md
@@ -82,6 +82,7 @@ title: Dependency Graph
 graph TD;
     OSK["/web/src/engine/osk"];
     KP["@keymanapp/keyboard-processor<br>(/common/web/keyboard-processor)"];
+    JSProc["/web/src/engine/js-processor"];
     OSK-->KP;
     WebUtils["@keymanapp/web-utils<br>(/common/web/utils)"];
     KP---->WebUtils;
@@ -107,6 +108,7 @@ graph TD;
     Fully headless components`"]
         direction LR
         KP;
+        JSProc-->KP;
         WebUtils;
         PredText;
         Gestures;
@@ -127,9 +129,9 @@ graph TD;
         OSK-->Gestures;
         Interfaces["/web/src/engine/interfaces"];
         Interfaces-->KP;
+        Interfaces-->JSProc;
         OSK-->Interfaces;
         CommonEngine["/web/src/engine/main"];
-        CommonEngine-->Interfaces;
         CommonEngine-->Device;
         CommonEngine-->KeyboardCache;
         CommonEngine-->OSK;
diff --git a/web/build.sh b/web/build.sh
index 7248f5c35a..6f4737710a 100755
--- a/web/build.sh
+++ b/web/build.sh
@@ -27,6 +27,7 @@ builder_describe "Builds engine modules for Keyman Engine for Web (KMW)." \
   ":engine/dom-utils         A common subset of function used for DOM calculations, layout, etc" \
   ":engine/events            Specialized classes utilized to support KMW API events" \
   ":engine/element-wrappers  Subset used to integrate with website elements" \
+  ":engine/js-processor      Build JS processor for KMW" \
   ":engine/main              Builds all common code used by KMW's app/-level targets" \
   ":engine/osk               Builds the Web OSK module" \
   ":engine/package-cache     Subset used to collate keyboards and request them from the cloud" \
@@ -57,6 +58,7 @@ builder_describe_outputs \
   build:engine/dom-utils        "/web/build/engine/dom-utils/obj/index.js" \
   build:engine/events           "/web/build/engine/events/lib/index.mjs" \
   build:engine/element-wrappers "/web/build/engine/element-wrappers/lib/index.mjs" \
+  build:engine/js-processor     "/web/build/engine/js-processor/lib/index.mjs" \
   build:engine/main             "/web/build/engine/main/lib/index.mjs" \
   build:engine/osk              "/web/build/engine/osk/lib/index.mjs" \
   build:engine/package-cache    "/web/build/engine/package-cache/lib/index.mjs" \
diff --git a/web/package.json b/web/package.json
index 458ea85de0..4baff29490 100644
--- a/web/package.json
+++ b/web/package.json
@@ -37,6 +37,11 @@
       "types": "./build/engine/events/obj/index.d.ts",
       "import": "./build/engine/events/obj/index.js"
     },
+    "./engine/js-processor": {
+      "es6-bundling": "./src/engine/js-processor/src/index.ts",
+      "types": "./build/engine/js-processor/obj/index.d.ts",
+      "import": "./build/engine/js-processor/obj/index.js"
+    },
     "./engine/package-cache": {
       "es6-bundling": "./src/engine/package-cache/src/index.ts",
       "types": "./build/engine/package-cache/obj/index.d.ts",
diff --git a/web/src/app/browser/src/beepHandler.ts b/web/src/app/browser/src/beepHandler.ts
index 3659f8d7fd..eb6d6583ee 100644
--- a/web/src/app/browser/src/beepHandler.ts
+++ b/web/src/app/browser/src/beepHandler.ts
@@ -1,4 +1,4 @@
-import { type KeyboardInterface } from '@keymanapp/keyboard-processor';
+import { type KeyboardInterface } from 'keyman/engine/js-processor';
 import { DesignIFrame, OutputTarget } from 'keyman/engine/element-wrappers';
 
 // Utility object used to handle beep (keyboard error response) operations.
diff --git a/web/src/app/browser/src/configuration.ts b/web/src/app/browser/src/configuration.ts
index 07be8264e7..4f2f268438 100644
--- a/web/src/app/browser/src/configuration.ts
+++ b/web/src/app/browser/src/configuration.ts
@@ -1,7 +1,8 @@
 import { EngineConfiguration, InitOptionSpec, InitOptionDefaults } from "keyman/engine/main";
 
 import { OutputTarget as DOMOutputTarget } from 'keyman/engine/element-wrappers';
-import { isEmptyTransform, OutputTarget, RuleBehavior } from '@keymanapp/keyboard-processor';
+import { isEmptyTransform, OutputTarget } from '@keymanapp/keyboard-processor';
+import { RuleBehavior } from 'keyman/engine/js-processor';
 import { AlertHost } from "./utils/alertHost.js";
 import { whenDocumentReady } from "./utils/documentReady.js";
 
diff --git a/web/src/app/browser/src/hardwareEventKeyboard.ts b/web/src/app/browser/src/hardwareEventKeyboard.ts
index 29e867aa13..f6874fc77b 100644
--- a/web/src/app/browser/src/hardwareEventKeyboard.ts
+++ b/web/src/app/browser/src/hardwareEventKeyboard.ts
@@ -1,4 +1,5 @@
-import { Codes, DeviceSpec, KeyEvent, KeyMapping, Keyboard, KeyboardProcessor } from '@keymanapp/keyboard-processor';
+import { Codes, DeviceSpec, KeyEvent, KeyMapping, Keyboard } from '@keymanapp/keyboard-processor';
+import { KeyboardProcessor } from 'keyman/engine/js-processor';
 import { ModifierKeyConstants } from '@keymanapp/common-types';
 
 import { HardKeyboard, processForMnemonicsAndLegacy } from 'keyman/engine/main';
diff --git a/web/src/app/webview/src/keymanEngine.ts b/web/src/app/webview/src/keymanEngine.ts
index ba98f8c477..dfae058a65 100644
--- a/web/src/app/webview/src/keymanEngine.ts
+++ b/web/src/app/webview/src/keymanEngine.ts
@@ -1,4 +1,5 @@
-import { DefaultRules, DeviceSpec, RuleBehavior } from '@keymanapp/keyboard-processor'
+import { DeviceSpec, DefaultRules } from '@keymanapp/keyboard-processor'
+import { RuleBehavior } from 'keyman/engine/js-processor';
 import { KeymanEngine as KeymanEngineBase, KeyboardInterface } from 'keyman/engine/main';
 import { AnchoredOSKView, ViewConfiguration, StaticActivator } from 'keyman/engine/osk';
 import { getAbsoluteX, getAbsoluteY } from 'keyman/engine/dom-utils';
diff --git a/web/src/engine/events/src/index.ts b/web/src/engine/events/src/index.ts
index 2d95307bc9..ee5674b66c 100644
--- a/web/src/engine/events/src/index.ts
+++ b/web/src/engine/events/src/index.ts
@@ -1,4 +1,3 @@
 export { DomEventTracker } from './domEventTracker.js';
 export { EmitterListenerSpy } from './emitterListenerSpy.js';
-export * from './keyEventSource.interface.js';
 export * from './legacyEventEmitter.js';
\ No newline at end of file
diff --git a/web/src/engine/interfaces/build.sh b/web/src/engine/interfaces/build.sh
index ca61e64865..528083d4d8 100755
--- a/web/src/engine/interfaces/build.sh
+++ b/web/src/engine/interfaces/build.sh
@@ -15,6 +15,7 @@ SUBPROJECT_NAME=engine/interfaces
 builder_describe "Builds configuration subclasses used by the Keyman Engine for Web (KMW)." \
   "@/common/web/es-bundling" \
   "@/common/web/keyboard-processor" \
+  "@/web/src/engine/js-processor" \
   "clean" \
   "configure" \
   "build" \
diff --git a/web/src/engine/interfaces/src/prediction/predictionContext.ts b/web/src/engine/interfaces/src/prediction/predictionContext.ts
index d47bf4b8e2..90427c3020 100644
--- a/web/src/engine/interfaces/src/prediction/predictionContext.ts
+++ b/web/src/engine/interfaces/src/prediction/predictionContext.ts
@@ -1,6 +1,7 @@
 import { EventEmitter } from "eventemitter3";
 import { type LanguageProcessorSpec , ReadySuggestions, type InvalidateSourceEnum, StateChangeHandler } from './languageProcessor.interface.js';
-import { type KeyboardProcessor, type OutputTarget } from "@keymanapp/keyboard-processor";
+import { type OutputTarget } from "@keymanapp/keyboard-processor";
+import { type KeyboardProcessor } from 'keyman/engine/js-processor';
 
 interface PredictionContextEventMap {
   update: (suggestions: Suggestion[]) => void;
diff --git a/web/src/engine/interfaces/tsconfig.json b/web/src/engine/interfaces/tsconfig.json
index d5a193e021..634e62bada 100644
--- a/web/src/engine/interfaces/tsconfig.json
+++ b/web/src/engine/interfaces/tsconfig.json
@@ -13,5 +13,6 @@
 
   "references": [
     { "path": "../../../../common/web/keyboard-processor" },
+    { "path": "../js-processor" }
   ]
 }
diff --git a/web/src/engine/js-processor/build.sh b/web/src/engine/js-processor/build.sh
new file mode 100755
index 0000000000..57adbd1dd2
--- /dev/null
+++ b/web/src/engine/js-processor/build.sh
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+## START STANDARD BUILD SCRIPT INCLUDE
+# adjust relative paths as necessary
+THIS_SCRIPT="$(readlink -f "${BASH_SOURCE[0]}")"
+. "${THIS_SCRIPT%/*}/../../../../resources/build/builder.inc.sh"
+## END STANDARD BUILD SCRIPT INCLUDE
+
+SUBPROJECT_NAME=engine/js-processor
+
+. "${KEYMAN_ROOT}/web/common.inc.sh"
+. "${KEYMAN_ROOT}/resources/shellHelperFunctions.sh"
+
+# ################################ Main script ################################
+
+builder_describe "Builds configuration subclasses used by the Keyman Engine for Web (KMW)." \
+  "clean" \
+  "configure" \
+  "build" \
+  "test" \
+  "--ci+                     Set to utilize CI-based test configurations & reporting."
+
+builder_describe_outputs \
+  configure    "/node_modules" \
+  build        "/web/build/${SUBPROJECT_NAME}/lib/index.mjs"
+
+builder_parse "$@"
+
+#### Build action definitions ####
+
+do_build () {
+  compile "${SUBPROJECT_NAME}"
+
+  ${BUNDLE_CMD} "${KEYMAN_ROOT}/web/build/${SUBPROJECT_NAME}/obj/index.js" \
+    --out         "${KEYMAN_ROOT}/web/build/${SUBPROJECT_NAME}/lib/index.mjs" \
+    --format esm
+}
+
+builder_run_action configure verify_npm_setup
+builder_run_action clean rm -rf "${KEYMAN_ROOT}/web/build/${SUBPROJECT_NAME}"
+builder_run_action build do_build
diff --git a/web/src/engine/js-processor/src/index.ts b/web/src/engine/js-processor/src/index.ts
new file mode 100644
index 0000000000..f87a044bd7
--- /dev/null
+++ b/web/src/engine/js-processor/src/index.ts
@@ -0,0 +1,6 @@
+export { default as KeyboardProcessor } from "./keyboardProcessor.js";
+export * from "./keyboardProcessor.js";
+export { default as RuleBehavior } from "./ruleBehavior.js";
+export * from './kbdInterface.js';
+export { default as KeyboardInterface } from "./kbdInterface.js";
+export * from "./systemStores.js";
diff --git a/common/web/keyboard-processor/src/text/kbdInterface.ts b/web/src/engine/js-processor/src/kbdInterface.ts
similarity index 96%
rename from common/web/keyboard-processor/src/text/kbdInterface.ts
rename to web/src/engine/js-processor/src/kbdInterface.ts
index 438d328f0d..6272637d04 100644
--- a/common/web/keyboard-processor/src/text/kbdInterface.ts
+++ b/web/src/engine/js-processor/src/kbdInterface.ts
@@ -7,18 +7,9 @@
 
 import { type DeviceSpec } from "@keymanapp/web-utils";
 import { ModifierKeyConstants } from '@keymanapp/common-types';
-
-import Codes from "./codes.js";
-import type KeyEvent from "./keyEvent.js";
-import type { Deadkey } from "./deadkeys.js";
-import KeyMapping from "./keyMapping.js";
-import { SystemStore, MutableSystemStore, PlatformSystemStore } from "./systemStores.js";
-import type { VariableStoreSerializer } from "./keyboardProcessor.js";
-import type OutputTarget from "./outputTarget.js";
-import { Mock } from "./outputTarget.js";
+import { Codes, type KeyEvent, type Deadkey, KeyMapping, type OutputTarget, Mock, Keyboard, KeyboardHarness, KeyboardKeymanGlobal, VariableStoreDictionary } from "@keymanapp/keyboard-processor";
 import RuleBehavior from "./ruleBehavior.js";
-import Keyboard, { VariableStoreDictionary } from "../keyboards/keyboard.js";
-import { KeyboardHarness, KeyboardKeymanGlobal } from "../keyboards/keyboardHarness.js";
+import { ComplexKeyboardStore, type KeyboardStore, KeyboardStoreElement, SystemStoreIDs, SystemStore, MutableSystemStore, PlatformSystemStore, VariableStore, VariableStoreSerializer } from "./systemStores.js";
 
 //#endregion
 
@@ -30,20 +21,6 @@ export class KeyInformation {
   modifiers: number;
 }
 
-/*
-* Type alias definitions to reflect the parameters of the fullContextMatch() callback (KMW 10+).
-* No constructors or methods since keyboards will not utilize the same backing prototype, and
-* property names are shorthanded to promote minification.
-*/
-type PlainKeyboardStore = string;
-
-export type KeyboardStoreElement = (string|StoreNonCharEntry);
-export type ComplexKeyboardStore = KeyboardStoreElement[];
-
-type KeyboardStore = PlainKeyboardStore | ComplexKeyboardStore;
-
-export type VariableStore = {[name: string]: string};
-
 type RuleChar = string;
 
 class RuleDeadkey {
@@ -70,7 +47,7 @@ class ContextAny {
   /**
    * If set to true, negates the 'any'.
    */
-  ['n']: boolean|0|1;
+  ['n']: boolean | 0 | 1;
 }
 
 class RuleIndex {
@@ -115,7 +92,7 @@ class StoreBeep {
 type ContextNonCharEntry = RuleDeadkey | ContextAny | RuleIndex | ContextEx | ContextNul;
 type ContextEntry = RuleChar | ContextNonCharEntry;
 
-type StoreNonCharEntry = RuleDeadkey | StoreBeep;
+export type StoreNonCharEntry = RuleDeadkey | StoreBeep;
 
 /**
  * Cache of context storing and retrieving return values from KC
@@ -183,13 +160,6 @@ class CachedContextEx {
   }
 };
 
-export enum SystemStoreIDs {
-  TSS_LAYER = 33,
-  TSS_PLATFORM = 31,
-  TSS_NEWLAYER = 42,
-  TSS_OLDLAYER = 43
-}
-
 //#endregion
 
 export default class KeyboardInterface extends KeyboardHarness {
diff --git a/common/web/keyboard-processor/src/text/keyboardProcessor.ts b/web/src/engine/js-processor/src/keyboardProcessor.ts
similarity index 95%
rename from common/web/keyboard-processor/src/text/keyboardProcessor.ts
rename to web/src/engine/js-processor/src/keyboardProcessor.ts
index 836c9912a6..12efa4e951 100644
--- a/common/web/keyboard-processor/src/text/keyboardProcessor.ts
+++ b/web/src/engine/js-processor/src/keyboardProcessor.ts
@@ -1,23 +1,21 @@
+/*
+ * Keyman is copyright (C) SIL International. MIT License.
+ *
+ * Implementation of the JavaScript keyboard processor
+ */
+
 // #region Big ol' list of imports
 
 import { EventEmitter } from 'eventemitter3';
-
-import Codes from "./codes.js";
-import type Keyboard from "../keyboards/keyboard.js";
-import { MinimalKeymanGlobal } from '../keyboards/keyboardHarness.js';
-import KeyEvent from "./keyEvent.js";
-import { Layouts } from "../keyboards/defaultLayouts.js";
-import type { MutableSystemStore } from "./systemStores.js";
-
-import DefaultRules, { EmulationKeystrokes } from "./defaultRules.js";
-import type OutputTarget from "./outputTarget.js";
-import { Mock } from "./outputTarget.js";
-
-import KeyboardInterface, { SystemStoreIDs, VariableStore } from "./kbdInterface.js";
-import RuleBehavior from "./ruleBehavior.js";
-
-import { DeviceSpec, globalObject } from "@keymanapp/web-utils";
 import { ModifierKeyConstants } from '@keymanapp/common-types';
+import {
+  Codes, type Keyboard, MinimalKeymanGlobal, KeyEvent, Layouts,
+  type OutputTarget, Mock, DefaultRules, EmulationKeystrokes
+} from "@keymanapp/keyboard-processor";
+import RuleBehavior from "./ruleBehavior.js";
+import KeyboardInterface from './kbdInterface.js';
+import { DeviceSpec, globalObject } from "@keymanapp/web-utils";
+import { type MutableSystemStore, SystemStoreIDs } from "./systemStores.js";
 
 // #endregion
 
@@ -26,11 +24,6 @@ import { ModifierKeyConstants } from '@keymanapp/common-types';
 export type BeepHandler = (outputTarget: OutputTarget) => void;
 export type LogMessageHandler = (str: string) => void;
 
-export interface VariableStoreSerializer {
-  loadStore(keyboardID: string, storeName: string): VariableStore;
-  saveStore(keyboardID: string, storeName: string, storeMap: VariableStore): void;
-}
-
 export interface ProcessorInitOptions {
   baseLayout?: string;
   keyboardInterface?: KeyboardInterface;
@@ -174,7 +167,7 @@ export default class KeyboardProcessor extends EventEmitter<EventMap> {
     let isMnemonic = this.activeKeyboard && this.activeKeyboard.isMnemonic;
 
     if(!matched) {
-      if((char = this.defaultRules.forAny(Lkc, isMnemonic)) != null) {
+      if((char = this.defaultRules.forAny(Lkc, isMnemonic, ruleBehavior)) != null) {
         special = this.defaultRules.forSpecialEmulation(Lkc)
         if(special == EmulationKeystrokes.Backspace) {
           // A browser's default backspace may fail to delete both parts of an SMP character.
@@ -277,7 +270,8 @@ export default class KeyboardProcessor extends EventEmitter<EventMap> {
 
     const lockNames  = ['CAPS', 'NUM_LOCK', 'SCROLL_LOCK'] as const;
     const lockKeys = ['K_CAPS', 'K_NUMLOCK', 'K_SCROLL'] as const;
-    const lockModifiers = [ ModifierKeyConstants.CAPITALFLAG, ModifierKeyConstants.NUMLOCKFLAG, ModifierKeyConstants.SCROLLFLAG] as const;
+    const lockModifiers = [ModifierKeyConstants.CAPITALFLAG, ModifierKeyConstants.NUMLOCKFLAG, ModifierKeyConstants.SCROLLFLAG] as const;
+
 
     if(!this.activeKeyboard) {
       return true;
@@ -329,6 +323,8 @@ export default class KeyboardProcessor extends EventEmitter<EventMap> {
     const lockModifiers = [ModifierKeyConstants.CAPITALFLAG, ModifierKeyConstants.NUMLOCKFLAG, ModifierKeyConstants.SCROLLFLAG] as const;
     const noLockModifers = [ModifierKeyConstants.NOTCAPITALFLAG, ModifierKeyConstants.NOTNUMLOCKFLAG, ModifierKeyConstants.NOTSCROLLFLAG] as const;
 
+
+
     for(let i=0; i < lockKeys.length; i++) {
       const key = lockKeys[i];
       const flag = this.stateKeys[key];
diff --git a/common/web/keyboard-processor/src/text/ruleBehavior.ts b/web/src/engine/js-processor/src/ruleBehavior.ts
similarity index 96%
rename from common/web/keyboard-processor/src/text/ruleBehavior.ts
rename to web/src/engine/js-processor/src/ruleBehavior.ts
index e5d669e909..08881eabcc 100644
--- a/common/web/keyboard-processor/src/text/ruleBehavior.ts
+++ b/web/src/engine/js-processor/src/ruleBehavior.ts
@@ -1,9 +1,8 @@
 ///<reference types="@keymanapp/models-types" />
 
 import KeyboardProcessor from "./keyboardProcessor.js";
-import OutputTarget, { Mock, type Transcription } from "./outputTarget.js";
-import { VariableStoreDictionary } from "../keyboards/keyboard.js";
-import type { VariableStore } from "./kbdInterface.js";
+import { OutputTarget, Mock, type Transcription, VariableStoreDictionary } from "@keymanapp/keyboard-processor";
+import { type VariableStore } from "./systemStores.js";
 
 /**
  * Represents the commands and state changes that result from a matched keyboard rule.
diff --git a/common/web/keyboard-processor/src/text/systemStores.ts b/web/src/engine/js-processor/src/systemStores.ts
similarity index 74%
rename from common/web/keyboard-processor/src/text/systemStores.ts
rename to web/src/engine/js-processor/src/systemStores.ts
index 13184baafe..9d02dbddbc 100644
--- a/common/web/keyboard-processor/src/text/systemStores.ts
+++ b/web/src/engine/js-processor/src/systemStores.ts
@@ -1,5 +1,31 @@
-import type KeyboardInterface from "./kbdInterface.js";
-import { SystemStoreIDs } from "./kbdInterface.js";
+import { type KeyboardHarness } from '@keymanapp/keyboard-processor';
+import { StoreNonCharEntry } from './kbdInterface.js';
+
+export enum SystemStoreIDs {
+  TSS_LAYER = 33,
+  TSS_PLATFORM = 31,
+  TSS_NEWLAYER = 42,
+  TSS_OLDLAYER = 43
+}
+
+/*
+* Type alias definitions to reflect the parameters of the fullContextMatch() callback (KMW 10+).
+* No constructors or methods since keyboards will not utilize the same backing prototype, and
+* property names are shorthanded to promote minification.
+*/
+type PlainKeyboardStore = string;
+
+export type KeyboardStoreElement = (string | StoreNonCharEntry);
+export type ComplexKeyboardStore = KeyboardStoreElement[];
+
+export type KeyboardStore = PlainKeyboardStore | ComplexKeyboardStore;
+
+export type VariableStore = { [name: string]: string };
+
+export interface VariableStoreSerializer {
+  loadStore(keyboardID: string, storeName: string): VariableStore;
+  saveStore(keyboardID: string, storeName: string, storeMap: VariableStore): void;
+}
 
 /**
  * Defines common behaviors associated with system stores.
@@ -61,9 +87,9 @@ export class MutableSystemStore extends SystemStore {
  * Handles checks against the current platform.
  */
 export class PlatformSystemStore extends SystemStore {
-  private readonly kbdInterface: KeyboardInterface;
+  private readonly kbdInterface: KeyboardHarness;
 
-  constructor(keyboardInterface: KeyboardInterface) {
+  constructor(keyboardInterface: KeyboardHarness) {
     super(SystemStoreIDs.TSS_PLATFORM);
 
     this.kbdInterface = keyboardInterface;
@@ -131,4 +157,4 @@ export class PlatformSystemStore extends SystemStore {
     // Everything we checked against was valid and had matches - it's a match!
     return true;
   }
-}
\ No newline at end of file
+}
diff --git a/web/src/engine/js-processor/tsconfig.json b/web/src/engine/js-processor/tsconfig.json
new file mode 100644
index 0000000000..a57467139b
--- /dev/null
+++ b/web/src/engine/js-processor/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  // While the actual references themselves are headless, it compiles against the DOM-reliant OSK module.
+  "extends": "../../tsconfig.dom.json",
+
+  "compilerOptions": {
+    "baseUrl": "./",
+    "outDir": "../../../build/engine/js-processor/obj/",
+    "tsBuildInfoFile": "../../../build/engine/js-processor/obj/tsconfig.tsbuildinfo",
+    "rootDir": "./src"
+  },
+
+  "include": [ "**/*.ts" ],
+}
diff --git a/web/src/engine/main/build.sh b/web/src/engine/main/build.sh
index cceb9b4b8b..4e6ca67db1 100755
--- a/web/src/engine/main/build.sh
+++ b/web/src/engine/main/build.sh
@@ -18,6 +18,7 @@ builder_describe "Builds the Keyman Engine for Web's common top-level base class
   "@/common/predictive-text" \
   "@/web/src/engine/interfaces build" \
   "@/web/src/engine/device-detect build" \
+  "@/web/src/engine/js-processor build" \
   "@/web/src/engine/package-cache build" \
   "@/web/src/engine/osk build" \
   "@/developer/src/kmc-model test" \
diff --git a/web/src/engine/main/src/contextManagerBase.ts b/web/src/engine/main/src/contextManagerBase.ts
index c3f9581003..e745dbe312 100644
--- a/web/src/engine/main/src/contextManagerBase.ts
+++ b/web/src/engine/main/src/contextManagerBase.ts
@@ -1,5 +1,6 @@
 import { EventEmitter } from 'eventemitter3';
-import { ManagedPromise, type Keyboard, type KeyboardInterface, type OutputTarget } from '@keymanapp/keyboard-processor';
+import { ManagedPromise, type Keyboard, type OutputTarget } from '@keymanapp/keyboard-processor';
+import { type KeyboardInterface } from 'keyman/engine/js-processor';
 import { StubAndKeyboardCache, type KeyboardStub } from 'keyman/engine/package-cache';
 import { PredictionContext } from 'keyman/engine/interfaces';
 import { EngineConfiguration } from './engineConfiguration.js';
diff --git a/web/src/engine/main/src/engineConfiguration.ts b/web/src/engine/main/src/engineConfiguration.ts
index c66d3bd805..bb82844c56 100644
--- a/web/src/engine/main/src/engineConfiguration.ts
+++ b/web/src/engine/main/src/engineConfiguration.ts
@@ -1,6 +1,7 @@
 import { EventEmitter } from "eventemitter3";
 
-import { DeviceSpec, KeyboardProperties, ManagedPromise, OutputTarget, physicalKeyDeviceAlias, RuleBehavior, SpacebarText } from "@keymanapp/keyboard-processor";
+import { DeviceSpec, KeyboardProperties, ManagedPromise, OutputTarget, physicalKeyDeviceAlias, SpacebarText } from "@keymanapp/keyboard-processor";
+import { RuleBehavior } from 'keyman/engine/js-processor';
 import { PathConfiguration, PathOptionDefaults, PathOptionSpec } from "keyman/engine/interfaces";
 import { Device } from "keyman/engine/device-detect";
 import { KeyboardStub } from "keyman/engine/package-cache";
diff --git a/web/src/engine/main/src/hardKeyboard.ts b/web/src/engine/main/src/hardKeyboard.ts
index a07904f4a6..491073f729 100644
--- a/web/src/engine/main/src/hardKeyboard.ts
+++ b/web/src/engine/main/src/hardKeyboard.ts
@@ -1,6 +1,7 @@
 import { EventEmitter } from "eventemitter3";
-import { Keyboard, KeyMapping, KeyEvent, type RuleBehavior, Codes } from "@keymanapp/keyboard-processor";
-import { KeyEventSourceInterface } from 'keyman/engine/events';
+import { Keyboard, KeyMapping, KeyEvent, Codes } from "@keymanapp/keyboard-processor";
+import { type RuleBehavior } from 'keyman/engine/js-processor';
+import { KeyEventSourceInterface } from 'keyman/engine/osk';
 import { ModifierKeyConstants } from '@keymanapp/common-types';
 
 interface EventMap {
diff --git a/web/src/engine/main/src/headless/inputProcessor.ts b/web/src/engine/main/src/headless/inputProcessor.ts
index 7b89a0e242..99a31db609 100644
--- a/web/src/engine/main/src/headless/inputProcessor.ts
+++ b/web/src/engine/main/src/headless/inputProcessor.ts
@@ -12,15 +12,12 @@ import {
   Codes,
   isEmptyTransform,
   type Keyboard,
-  KeyboardInterface,
-  KeyboardProcessor,
   type KeyEvent,
   Mock,
   type OutputTarget,
-  type ProcessorInitOptions,
-  RuleBehavior,
-  SystemStoreIDs,
 } from "@keymanapp/keyboard-processor";
+import { KeyboardInterface, KeyboardProcessor, RuleBehavior, type ProcessorInitOptions, SystemStoreIDs } from 'keyman/engine/js-processor';
+
 import { TranscriptionCache } from "./transcriptionCache.js";
 
 export class InputProcessor {
diff --git a/web/src/engine/main/src/keyboardInterface.ts b/web/src/engine/main/src/keyboardInterface.ts
index a18bafecd0..d966c26bad 100644
--- a/web/src/engine/main/src/keyboardInterface.ts
+++ b/web/src/engine/main/src/keyboardInterface.ts
@@ -1,6 +1,5 @@
-import {
-  KeyboardInterface as KeyboardInterfaceBase, KeyboardObject,
-} from "@keymanapp/keyboard-processor";
+import { KeyboardObject } from "@keymanapp/keyboard-processor";
+import { KeyboardInterface as KeyboardInterfaceBase } from 'keyman/engine/js-processor';
 import { KeyboardStub, RawKeyboardStub, toUnprefixedKeyboardId as unprefixed } from 'keyman/engine/package-cache';
 
 import { ContextManagerBase } from './contextManagerBase.js';
diff --git a/web/src/engine/main/src/keymanEngine.ts b/web/src/engine/main/src/keymanEngine.ts
index eaa54e5994..86ff9d5898 100644
--- a/web/src/engine/main/src/keymanEngine.ts
+++ b/web/src/engine/main/src/keymanEngine.ts
@@ -1,4 +1,5 @@
-import { type Keyboard, KeyboardKeymanGlobal, ProcessorInitOptions } from "@keymanapp/keyboard-processor";
+import { type KeyEvent, type Keyboard, KeyboardKeymanGlobal } from "@keymanapp/keyboard-processor";
+import { ProcessorInitOptions, RuleBehavior } from 'keyman/engine/js-processor';
 import { DOMKeyboardLoader as KeyboardLoader } from "@keymanapp/keyboard-processor/dom-keyboard-loader";
 import { InputProcessor } from './headless/inputProcessor.js';
 import { OSKView } from "keyman/engine/osk";
@@ -10,7 +11,7 @@ import KeyboardInterface from "./keyboardInterface.js";
 import { ContextManagerBase } from "./contextManagerBase.js";
 import HardKeyboardBase from "./hardKeyboard.js";
 import { LegacyAPIEvents } from "./legacyAPIEvents.js";
-import { KeyEventHandler, EventNames, EventListener, LegacyEventEmitter } from "keyman/engine/events";
+import { EventNames, EventListener, LegacyEventEmitter } from "keyman/engine/events";
 import DOMCloudRequester from "keyman/engine/package-cache/dom-requester";
 import KEYMAN_VERSION from "@keymanapp/keyman-version";
 
@@ -29,6 +30,9 @@ function determineBaseLayout(): string {
   }
 }
 
+export type KeyEventFullResultCallback = (result: RuleBehavior, error?: Error) => void;
+export type KeyEventFullHandler = (event: KeyEvent, callback?: KeyEventFullResultCallback) => void;
+
 export default class KeymanEngine<
   Configuration extends EngineConfiguration,
   ContextManager extends ContextManagerBase<any>,
@@ -47,7 +51,7 @@ export default class KeymanEngine<
 
   protected keyEventRefocus?: () => void;
 
-  private keyEventListener: KeyEventHandler = (event, callback) => {
+  private keyEventListener: KeyEventFullHandler = (event, callback) => {
     const outputTarget = this.contextManager.activeTarget;
 
     if(!this.contextManager.activeKeyboard || !outputTarget) {
diff --git a/web/src/engine/main/src/variableStoreCookieSerializer.ts b/web/src/engine/main/src/variableStoreCookieSerializer.ts
index 35b51150c0..62c250329a 100644
--- a/web/src/engine/main/src/variableStoreCookieSerializer.ts
+++ b/web/src/engine/main/src/variableStoreCookieSerializer.ts
@@ -1,4 +1,4 @@
-import { VariableStore, VariableStoreSerializer } from "@keymanapp/keyboard-processor";
+import { VariableStore, VariableStoreSerializer } from 'keyman/engine/js-processor';
 import { CookieSerializer } from "keyman/engine/dom-utils";
 
 // While there's little reason we couldn't store all of a keyboard's store values within
diff --git a/web/src/engine/main/tsconfig.json b/web/src/engine/main/tsconfig.json
index 9711d06a77..e3b2b0616c 100644
--- a/web/src/engine/main/tsconfig.json
+++ b/web/src/engine/main/tsconfig.json
@@ -15,5 +15,6 @@
     { "path": "../osk" },
     { "path": "../package-cache" },
     { "path": "../interfaces" },
+    { "path": "../js-processor" }
   ]
 }
diff --git a/web/src/engine/osk/src/index.ts b/web/src/engine/osk/src/index.ts
index 388ea32750..f2a543e175 100644
--- a/web/src/engine/osk/src/index.ts
+++ b/web/src/engine/osk/src/index.ts
@@ -4,6 +4,7 @@ export { default as OSKView } from './views/oskView.js';
 export { default as FloatingOSKView, FloatingOSKViewConfiguration } from './views/floatingOskView.js';
 export { default as AnchoredOSKView } from './views/anchoredOskView.js';
 export { default as InlinedOSKView } from './views/inlinedOskView.js';
+export { type KeyEventResultCallback, type KeyEventHandler, KeyEventSourceInterface } from './views/keyEventSource.interface.js';
 export { BannerController } from './banner/bannerController.js';
 // Is referenced by at least one desktop UI module.
 export { FloatingOSKCookie as FloatingOSKViewCookie } from './views/floatingOskCookie.js';
diff --git a/web/src/engine/events/src/keyEventSource.interface.ts b/web/src/engine/osk/src/views/keyEventSource.interface.ts
similarity index 78%
rename from web/src/engine/events/src/keyEventSource.interface.ts
rename to web/src/engine/osk/src/views/keyEventSource.interface.ts
index d3c39fa49d..36a065bd32 100644
--- a/web/src/engine/events/src/keyEventSource.interface.ts
+++ b/web/src/engine/osk/src/views/keyEventSource.interface.ts
@@ -1,5 +1,6 @@
 import { EventEmitter } from "eventemitter3";
-import { type KeyEvent, type RuleBehavior } from "@keymanapp/keyboard-processor";
+import { type KeyEvent } from "@keymanapp/keyboard-processor";
+import { type RuleBehavior } from 'keyman/engine/js-processor';
 
 export type KeyEventResultCallback = (result: RuleBehavior, error?: Error) => void;
 export type KeyEventHandler = (event: KeyEvent, callback?: KeyEventResultCallback) => void;
diff --git a/web/src/engine/osk/src/views/oskView.ts b/web/src/engine/osk/src/views/oskView.ts
index d55eb8a8f8..2a400a8662 100644
--- a/web/src/engine/osk/src/views/oskView.ts
+++ b/web/src/engine/osk/src/views/oskView.ts
@@ -16,16 +16,16 @@ import {
   Keyboard,
   KeyboardProperties,
   ManagedPromise,
-  type MinimalCodesInterface,
-  type MutableSystemStore,
-  type SystemStoreMutationHandler
+  type MinimalCodesInterface
 } from '@keymanapp/keyboard-processor';
 import { createUnselectableElement, getAbsoluteX, getAbsoluteY, StylesheetManager } from 'keyman/engine/dom-utils';
-import { EventListener, KeyEventHandler, KeyEventSourceInterface, LegacyEventEmitter } from 'keyman/engine/events';
+import { EventListener, LegacyEventEmitter } from 'keyman/engine/events';
+import { type MutableSystemStore, type SystemStoreMutationHandler } from 'keyman/engine/js-processor';
 
 import Configuration from '../config/viewConfiguration.js';
 import Activator, { StaticActivator } from './activator.js';
 import TouchEventPromiseMap from './touchEventPromiseMap.js';
+import { KeyEventHandler, KeyEventSourceInterface } from './keyEventSource.interface.js';
 import { DEFAULT_GESTURE_PARAMS, GestureParams } from '../input/gestures/specsForLayout.js';
 
 // These will likely be eliminated from THIS file at some point.\
diff --git a/web/src/engine/osk/src/visualKeyboard.ts b/web/src/engine/osk/src/visualKeyboard.ts
index a8152a0db0..d082663454 100644
--- a/web/src/engine/osk/src/visualKeyboard.ts
+++ b/web/src/engine/osk/src/visualKeyboard.ts
@@ -31,7 +31,7 @@ import {
 
 import { createStyleSheet, StylesheetManager } from 'keyman/engine/dom-utils';
 
-import { KeyEventHandler, KeyEventResultCallback } from 'keyman/engine/events';
+import { KeyEventHandler, KeyEventResultCallback } from './views/keyEventSource.interface.js';
 
 import GlobeHint from './globehint.interface.js';
 import KeyboardView from './components/keyboardView.interface.js';
diff --git a/common/web/keyboard-processor/tests/dom/cases/domKeyboardLoader.spec.ts b/web/src/test/auto/dom/cases/keyboard-processor/domKeyboardLoader.spec.ts
similarity index 95%
rename from common/web/keyboard-processor/tests/dom/cases/domKeyboardLoader.spec.ts
rename to web/src/test/auto/dom/cases/keyboard-processor/domKeyboardLoader.spec.ts
index 1965adc853..63414662fa 100644
--- a/common/web/keyboard-processor/tests/dom/cases/domKeyboardLoader.spec.ts
+++ b/web/src/test/auto/dom/cases/keyboard-processor/domKeyboardLoader.spec.ts
@@ -1,7 +1,8 @@
 import { assert } from 'chai';
 
 import { DOMKeyboardLoader } from '@keymanapp/keyboard-processor/dom-keyboard-loader';
-import { extendString, KeyboardHarness, Keyboard, KeyboardInterface, MinimalKeymanGlobal, Mock, DeviceSpec, KeyboardKeymanGlobal } from '@keymanapp/keyboard-processor';
+import { extendString, KeyboardHarness, Keyboard, MinimalKeymanGlobal, Mock, DeviceSpec, KeyboardKeymanGlobal } from '@keymanapp/keyboard-processor';
+import { KeyboardInterface } from 'keyman/engine/js-processor';
 
 declare let window: typeof globalThis;
 // KeymanEngine from the web/ folder... when available.
diff --git a/web/src/test/auto/dom/kbdLoader.ts b/web/src/test/auto/dom/kbdLoader.ts
index 629ade205e..2254011857 100644
--- a/web/src/test/auto/dom/kbdLoader.ts
+++ b/web/src/test/auto/dom/kbdLoader.ts
@@ -4,11 +4,11 @@ import {
 
 import {
   Keyboard,
-  KeyboardInterface,
   KeyboardProperties,
   MinimalKeymanGlobal
 } from '@keymanapp/keyboard-processor';
 
+import { KeyboardInterface } from 'keyman/engine/js-processor';
 import { KeyboardStub } from 'keyman/engine/package-cache';
 
 const loader = new DOMKeyboardLoader(new KeyboardInterface(window, MinimalKeymanGlobal));
diff --git a/web/src/test/auto/headless/engine/interfaces/prediction/predictionContext.spec.js b/web/src/test/auto/headless/engine/interfaces/prediction/predictionContext.spec.js
index 6bd0f7555c..3738f6824e 100644
--- a/web/src/test/auto/headless/engine/interfaces/prediction/predictionContext.spec.js
+++ b/web/src/test/auto/headless/engine/interfaces/prediction/predictionContext.spec.js
@@ -4,7 +4,8 @@ import sinon from 'sinon';
 import { LanguageProcessor, TranscriptionCache } from 'keyman/engine/main';
 import { PredictionContext } from 'keyman/engine/interfaces';
 import { Worker as LMWorker } from "@keymanapp/lexical-model-layer/node";
-import { DeviceSpec, KeyboardProcessor, Mock } from '@keymanapp/keyboard-processor';
+import { DeviceSpec, Mock } from '@keymanapp/keyboard-processor';
+import { KeyboardProcessor } from 'keyman/engine/js-processor';
 
 function compileDummyModel(suggestionSets) {
   return `
diff --git a/web/src/tools/testing/recorder-core/src/nodeProctor.ts b/web/src/tools/testing/recorder-core/src/nodeProctor.ts
index 6f6d7fd6a0..852002d4b3 100644
--- a/web/src/tools/testing/recorder-core/src/nodeProctor.ts
+++ b/web/src/tools/testing/recorder-core/src/nodeProctor.ts
@@ -8,8 +8,9 @@ import {
   RecordedSyntheticKeystroke
 } from "./index.js";
 
-import { KeyboardInterface, KeyEvent, KeyEventSpec, KeyboardProcessor, Mock, type OutputTarget, KeyboardHarness } from "@keymanapp/keyboard-processor";
+import { KeyEvent, KeyEventSpec, Mock, type OutputTarget, KeyboardHarness } from "@keymanapp/keyboard-processor";
 import { DeviceSpec } from "@keymanapp/web-utils";
+import { KeyboardInterface, KeyboardProcessor } from 'keyman/engine/js-processor';
 
 export default class NodeProctor extends Proctor {
   private keyboardWithHarness: KeyboardHarness;
diff --git a/web/src/tools/testing/recorder-core/tsconfig.json b/web/src/tools/testing/recorder-core/tsconfig.json
index a7bd08c374..38af26e1a4 100644
--- a/web/src/tools/testing/recorder-core/tsconfig.json
+++ b/web/src/tools/testing/recorder-core/tsconfig.json
@@ -17,6 +17,7 @@
     { "path": "../../../../../common/web/keyman-version" },
     { "path": "../../../../../common/web/utils/" },
     { "path": "../../../../../common/web/keyboard-processor/" },
-    { "path": "../../../../../common/web/lm-message-types" }
+    { "path": "../../../../../common/web/lm-message-types" },
+    { "path": "../../../engine/js-processor" }
   ],
 }