fix(sdk-ts): raise engines floor to Node >=20 (audit F-11)

The new sdk-ts-compat lane immediately proved the declared >=18 floor
untestable: Vitest 4 imports util.styleText, which Node 18 does not
provide. Node 18 is end-of-life, so the floor rises honestly instead of
pinning an older toolchain; the required sdk-ts job covers Node 20 and the
compat lane covers 22.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: JuliaEdom

.github/workflows/ci.yml

@@ -522,17 +522,19 @@ jobs:
       - name: Verify package is publishable
         run: npm pack --dry-run
 
-  # Audit F-11: package.json declares engines.node >=18 but CI exercised only
-  # Node 20. This lane backs the declared floor (18) and the next LTS (22)
-  # without touching the required "sdk-ts" context above — a matrix inside
-  # that job would rename its check context and break branch protection.
+  # Audit F-11: CI must exercise every Node version the package claims. The
+  # first run of this lane proved the old ">=18" engines floor untestable
+  # (Vitest 4 needs util.styleText, absent on Node 18), so the floor was
+  # honestly raised to ">=20": the required "sdk-ts" job covers 20, this lane
+  # covers the next LTS. A matrix inside the required job would rename its
+  # check context and break branch protection.
   sdk-ts-compat:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     strategy:
       fail-fast: false
       matrix:
-        node-version: ["18", "22"]
+        node-version: ["22"]
     defaults:
       run:
         working-directory: sdk-ts

sdk-ts/CHANGELOG.md

@@ -13,6 +13,12 @@ Deprecation policy:
 
 ## [Unreleased]
 
+### Changed
+- `engines.node` floor raised from `>=18` to `>=20` (audit F-11). Node 18 is
+  end-of-life and the SDK toolchain (Vitest 4) needs `util.styleText`, which
+  Node 18 lacks — CI proved the declared 18 floor was untestable. CI now
+  exercises Node 20 (required lane) and 22 (compat lane).
+
 ### Added
 - `RetryPolicy` with exponential backoff, jitter, and `Retry-After` support for transient SDK failures
 - `CircuitBreaker`, `CircuitState`, and `CircuitOpenError` exports for repeated backend failure protection

sdk-ts/package.json

@@ -39,7 +39,7 @@
     "directory": "sdk-ts"
   },
   "engines": {
-    "node": ">=18"
+    "node": ">=20"
   },
   "devDependencies": {
     "typescript": "^7.0.2",