diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 0fe8f5a25..f40d74124 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -81,12 +81,30 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: 'lts/*'
-          cache: yarn
+          # NOTE: `cache: yarn` is intentionally NOT set. This repo is a Yarn
+          # Berry project (yarn.lock __metadata version 10). setup-node's
+          # `cache: yarn` resolves the cache folder using the yarn binary on
+          # PATH *during this step* — which is the runner's default Yarn
+          # Classic 1.x, because corepack's Berry shim isn't activated until
+          # the next step. That would cache the wrong (Classic) folder.
+          # Release runs only on workflow_run after CI success on main (low
+          # frequency), so the marginal cache benefit doesn't justify the
+          # misconfiguration risk. (qs-02 / TD-3.)
+
+      - name: Enable corepack (activate Yarn Berry from packageManager)
+        # Runs AFTER setup-node so corepack uses the pinned Node toolchain.
+        # `corepack enable` installs the yarn shim that resolves the version
+        # in package.json's `packageManager` field (yarn@4.15.0), so the
+        # install below runs under Berry — not the runner's default Yarn
+        # Classic 1.x, which silently ignores --immutable and mis-reads the
+        # v10 lockfile. (qs-02 / TD-3.)
+        run: corepack enable
 
       - name: Install Node dependencies
         # --immutable: error if yarn.lock drifts from package.json. Matches
         # the PHP SDK's pattern — prevents accidental lockfile mutation in
-        # CI while still catching out-of-sync lockfiles at PR time.
+        # CI while still catching out-of-sync lockfiles at PR time. Honored
+        # correctly now that corepack has activated Yarn Berry above.
         run: yarn install --immutable
 
       - name: Run semantic-release
diff --git a/.gitignore b/.gitignore
index 021544900..0e1344121 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,9 @@ node_modules/
 .yarn/cache
 .yarn/install-state.gz
 .pnp.*
+
+# Parity tooling — nested Berry project under tools/ (qs-02). Its .yarn
+# artifacts are NOT covered by the root-anchored patterns above, so ignore
+# them explicitly. tools/package.json + tools/yarn.lock ARE committed.
+tools/.yarn/cache
+tools/.yarn/install-state.gz
diff --git a/package.json b/package.json
index 35710b6fb..a7fcd8819 100644
--- a/package.json
+++ b/package.json
@@ -2,14 +2,13 @@
   "name": "convert-android-sdk-release-tooling",
   "private": true,
   "type": "module",
-  "description": "Release automation tooling and cross-SDK parity-vector generation for the Convert Android SDK.",
+  "description": "Release automation tooling for the Convert Android SDK (semantic-release). Cross-SDK parity-vector generation lives in tools/package.json and is intentionally isolated from this release install path.",
+  "packageManager": "yarn@4.15.0",
   "scripts": {
     "release": "semantic-release",
-    "release:dry-run": "semantic-release --dry-run --no-ci",
-    "generate:parity-vectors": "node tools/generate-parity-vectors.mjs > packages/core/src/test/resources/hash-parity-vectors.json"
+    "release:dry-run": "semantic-release --dry-run --no-ci"
   },
   "devDependencies": {
-    "@convertcom/js-sdk-bucketing": "file:../javascript-sdk/packages/bucketing",
     "@semantic-release/changelog": "^6.0.0",
     "@semantic-release/exec": "^7.0.0",
     "@semantic-release/git": "^10.0.0",
diff --git a/tools/PARITY.md b/tools/PARITY.md
index 8f3c742a5..c0b5adbf5 100644
--- a/tools/PARITY.md
+++ b/tools/PARITY.md
@@ -21,8 +21,14 @@ The android-sdk owns the **Kotlin side** of parity:
 - The vector file at `packages/core/src/test/resources/hash-parity-vectors.json`
   (committed; regenerated only from the JS SDK reference).
 - The generation script at `tools/generate-parity-vectors.mjs`
-  (committed; runs against `@convertcom/js-sdk-bucketing` from the
-  sibling javascript-sdk checkout).
+  (committed; runs against the PUBLISHED `@convertcom/js-sdk-bucketing`
+  npm package, pinned in `tools/package.json`). The script and its
+  dependency live in an isolated `tools/package.json` — deliberately
+  separate from the root release `package.json`, so the release pipeline
+  never installs the parity dependency. Regeneration is run from `tools/`
+  and needs no sibling javascript-sdk checkout (it resolves bucketing from
+  npm), making it portable and reproducible against the exact version
+  other Convert SDKs consume.
 - The Kotlin parity gate `HashParityTest.kt`.
 
 The JS side maintains its own equivalent parity suite. Other SDKs (PHP,
@@ -61,7 +67,7 @@ to silently regenerate.
    precise `description`). Then regenerate locally:
 
    ```sh
-   cd android-sdk
+   cd android-sdk/tools
    yarn install
    yarn generate:parity-vectors
    ```
diff --git a/tools/generate-parity-vectors.mjs b/tools/generate-parity-vectors.mjs
index a95557946..0bcc4db66 100644
--- a/tools/generate-parity-vectors.mjs
+++ b/tools/generate-parity-vectors.mjs
@@ -18,26 +18,33 @@
  * ──────────────────────────────────────────────────────────────────────
  * How to run
  * ──────────────────────────────────────────────────────────────────────
- *   cd android-sdk
- *   yarn install                              # once
+ * This tooling lives in its OWN package (android-sdk/tools), isolated from
+ * the root release package.json so the release pipeline never installs the
+ * parity dependency. Run it from tools/:
+ *
+ *   cd android-sdk/tools
+ *   yarn install                              # once (pulls bucketing from npm)
  *   yarn generate:parity-vectors              # regenerate vectors
- *   # or equivalently:
- *   node tools/generate-parity-vectors.mjs \
- *     > packages/core/src/test/resources/hash-parity-vectors.json
+ *   # or equivalently, from tools/:
+ *   node generate-parity-vectors.mjs \
+ *     > ../packages/core/src/test/resources/hash-parity-vectors.json
  *
  * ──────────────────────────────────────────────────────────────────────
  * Dependencies
  * ──────────────────────────────────────────────────────────────────────
  * Requires:
  *   - Node 20+ (uses ESM + top-level await-compatible runtime)
- *   - `@convertcom/js-sdk-bucketing` resolved via the `file:../javascript-sdk/
- *     packages/bucketing` devDependency in the android-sdk's package.json.
- *     That pulls in the PRE-BUILT `lib/index.mjs` which has murmurhash
- *     bundled in — no internet access needed at runtime.
+ *   - `@convertcom/js-sdk-bucketing` — the PUBLISHED npm package, pinned in
+ *     tools/package.json (`^3.1.2`). No sibling javascript-sdk checkout is
+ *     needed: regeneration is portable and reproducible against the exact
+ *     published version other Convert SDKs consume. The package ships a
+ *     PRE-BUILT `lib/index.mjs` with murmurhash bundled in.
  *
- * If the sibling javascript-sdk checkout moves or the bucketing lib
- * hasn't been built (no `lib/index.mjs`), run
- * `cd ../javascript-sdk && yarn install && yarn bucketing:build`.
+ * To regenerate against a newer JS SDK bucketing release, bump the version
+ * range in tools/package.json, run `yarn install` in tools/, then
+ * `yarn generate:parity-vectors`. A version bump that changes existing
+ * vectors is a cross-SDK breaking change — see "When the JS SDK changes
+ * hash logic" in PARITY.md.
  *
  * ──────────────────────────────────────────────────────────────────────
  * When to regenerate
diff --git a/tools/package.json b/tools/package.json
new file mode 100644
index 000000000..58734781d
--- /dev/null
+++ b/tools/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "convert-android-sdk-parity-tooling",
+  "private": true,
+  "type": "module",
+  "description": "Cross-SDK parity-vector generation for the Convert Android SDK. Regen-only; isolated from release tooling, and pinned to the PUBLISHED @convertcom/js-sdk-bucketing npm package so regeneration is portable (no sibling javascript-sdk checkout needed) and reproducible.",
+  "packageManager": "yarn@4.15.0",
+  "scripts": {
+    "generate:parity-vectors": "node generate-parity-vectors.mjs > ../packages/core/src/test/resources/hash-parity-vectors.json"
+  },
+  "devDependencies": {
+    "@convertcom/js-sdk-bucketing": "3.1.2"
+  }
+}
diff --git a/tools/yarn.lock b/tools/yarn.lock
new file mode 100644
index 000000000..5b8f8f943
--- /dev/null
+++ b/tools/yarn.lock
@@ -0,0 +1,26 @@
+# This file is generated by running "yarn install" inside your project.
+# Manual changes might be lost - proceed with caution!
+
+__metadata:
+  version: 10
+  cacheKey: 10c0
+
+"@convertcom/js-sdk-bucketing@npm:3.1.2":
+  version: 3.1.2
+  resolution: "@convertcom/js-sdk-bucketing@npm:3.1.2"
+  peerDependencies:
+    "@convertcom/js-sdk-enums": ">=2.3.0"
+    "@convertcom/js-sdk-logger": ">=2.1.2"
+    "@convertcom/js-sdk-types": ">=3.9.0"
+    "@convertcom/js-sdk-utils": ">=2.2.3"
+  checksum: 10c0/74f99e46613c0029949dea2ad53dbd58e1ebd4ac1c933052e93f8c7b8c641ac3460b041b17eb1599ead996d36c81097bdeba0fe97f012cd8bf2b3c435f5a1acc
+  languageName: node
+  linkType: hard
+
+"convert-android-sdk-parity-tooling@workspace:.":
+  version: 0.0.0-use.local
+  resolution: "convert-android-sdk-parity-tooling@workspace:."
+  dependencies:
+    "@convertcom/js-sdk-bucketing": "npm:3.1.2"
+  languageName: unknown
+  linkType: soft
diff --git a/yarn.lock b/yarn.lock
index 048470c01..85c7ea94f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2,7 +2,7 @@
 # Manual changes might be lost - proceed with caution!
 
 __metadata:
-  version: 9
+  version: 10
   cacheKey: 10c0
 
 "@babel/code-frame@npm:^7.0.0, @babel/code-frame@npm:^7.26.2":
@@ -30,18 +30,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@convertcom/js-sdk-bucketing@file:../javascript-sdk/packages/bucketing::locator=convert-android-sdk-release-tooling%40workspace%3A.":
-  version: 3.1.2
-  resolution: "@convertcom/js-sdk-bucketing@file:../javascript-sdk/packages/bucketing#../javascript-sdk/packages/bucketing::hash=e0b32a&locator=convert-android-sdk-release-tooling%40workspace%3A."
-  peerDependencies:
-    "@convertcom/js-sdk-enums": ">=2.3.0"
-    "@convertcom/js-sdk-logger": ">=2.1.2"
-    "@convertcom/js-sdk-types": ">=3.9.0"
-    "@convertcom/js-sdk-utils": ">=2.2.3"
-  checksum: 10c0/4cb42cbd7be9e596671396e5b8c8dbc46562e121bbeba6cbd4c4bffe708bb582553cc2e3cd3741352b9b3f8ce40e19dd562419a993fc14d39a601f008d6fb50f
-  languageName: node
-  linkType: hard
-
 "@isaacs/cliui@npm:^8.0.2":
   version: 8.0.2
   resolution: "@isaacs/cliui@npm:8.0.2"
@@ -1171,7 +1159,6 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "convert-android-sdk-release-tooling@workspace:."
   dependencies:
-    "@convertcom/js-sdk-bucketing": "file:../javascript-sdk/packages/bucketing"
     "@semantic-release/changelog": "npm:^6.0.0"
     "@semantic-release/exec": "npm:^7.0.0"
     "@semantic-release/git": "npm:^10.0.0"