diff --git a/docs/ci.md b/docs/ci.md
index 9e75399114c..20298e0a7df 100644
--- a/docs/ci.md
+++ b/docs/ci.md
@@ -53,7 +53,7 @@ Local changed-lane logic lives in `scripts/changed-lanes.mjs` and is executed by
 
 On pushes, the `checks` matrix adds the push-only `compat-node22` lane. On pull requests, that lane is skipped and the matrix stays focused on the normal test/channel lanes.
 
-The slowest Node test families are split or balanced so each job stays small: channel contracts split registry and core coverage into eight weighted shards each, auto-reply runs as three balanced workers instead of six tiny workers, and agentic gateway/plugin configs are spread across the existing source-only agentic Node jobs instead of waiting on built artifacts. `check-additional` keeps package-boundary compile/canary work together and separates it from runtime topology gateway/architecture work; the boundary guard shard runs its small independent guards concurrently inside one job, and the gateway watch regression uses the minimal `gatewayWatch` build profile instead of rebuilding the full CI artifact sidecar set.
+The slowest Node test families are split or balanced so each job stays small: channel contracts split registry and core coverage into eight weighted shards each, bundled plugin tests balance across five extension workers, auto-reply runs as three balanced workers instead of six tiny workers, and agentic gateway/plugin configs are spread across the existing source-only agentic Node jobs instead of waiting on built artifacts. `check-additional` keeps package-boundary compile/canary work together and separates it from runtime topology gateway/architecture work; the boundary guard shard runs its small independent guards concurrently inside one job, and the gateway watch regression uses the minimal `gatewayWatch` build profile instead of rebuilding the full CI artifact sidecar set.
 
 GitHub may mark superseded jobs as `cancelled` when a newer push lands on the same PR or `main` ref. Treat that as CI noise unless the newest run for the same ref is also failing. Aggregate shard checks use `!cancelled() && always()` so they still report normal shard failures but do not queue after the whole workflow has already been superseded.
 The CI concurrency key is versioned (`CI-v5-*`) so a GitHub-side zombie in an old queue group cannot indefinitely block newer main runs.
diff --git a/scripts/lib/extension-test-plan.mjs b/scripts/lib/extension-test-plan.mjs
index edeaad7ce57..2b07578648a 100644
--- a/scripts/lib/extension-test-plan.mjs
+++ b/scripts/lib/extension-test-plan.mjs
@@ -24,7 +24,7 @@ import { BUNDLED_PLUGIN_PATH_PREFIX, BUNDLED_PLUGIN_ROOT_DIR } from "./bundled-p
 import { listAvailableExtensionIds } from "./changed-extensions.mjs";
 
 const repoRoot = path.resolve(import.meta.dirname, "..", "..");
-export const DEFAULT_EXTENSION_TEST_SHARD_COUNT = 6;
+export const DEFAULT_EXTENSION_TEST_SHARD_COUNT = 5;
 const EXTENSION_TEST_COST_MULTIPLIERS = {
   "test/vitest/vitest.extension-feishu.config.ts": 1.6,
   "test/vitest/vitest.extension-msteams.config.ts": 1.6,