From a1828110704fade5281dde8b0d2e305d5b23dd54 Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Mon, 22 Jun 2026 10:53:33 +0800
Subject: [PATCH] fix(ci): smooth PR runner-registration bursts (#95625)

Merged via squash.

Prepared head SHA: 72b2b00bf82c3e4c58777c532e27ad6aa0dae114
Co-authored-by: vincentkoc <25068+vincentkoc@users.noreply.github.com>
Co-authored-by: vincentkoc <25068+vincentkoc@users.noreply.github.com>
Reviewed-by: @vincentkoc
---
 .github/workflows/ci.yml                |  8 ++++++++
 test/scripts/ci-workflow-guards.test.ts | 13 +++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c7ba073c62cf..fd2ce7310793 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -819,6 +819,7 @@ jobs:
     timeout-minutes: 60
     strategy:
       fail-fast: false
+      max-parallel: 4
       matrix: ${{ fromJson(needs.preflight.outputs.checks_fast_core_matrix) }}
     steps:
       - name: Checkout
@@ -908,6 +909,7 @@ jobs:
     timeout-minutes: 60
     strategy:
       fail-fast: false
+      max-parallel: 4
       matrix: ${{ fromJson(needs.preflight.outputs.plugin_contracts_matrix) }}
     steps:
       - name: Checkout
@@ -988,6 +990,7 @@ jobs:
     timeout-minutes: 60
     strategy:
       fail-fast: false
+      max-parallel: 4
       matrix: ${{ fromJson(needs.preflight.outputs.channel_contracts_matrix) }}
     steps:
       - name: Checkout
@@ -1140,6 +1143,7 @@ jobs:
     timeout-minutes: 60
     strategy:
       fail-fast: false
+      max-parallel: 6
       matrix: ${{ fromJson(needs.preflight.outputs.checks_node_core_nondist_matrix) }}
     steps:
       - name: Checkout
@@ -1248,6 +1252,7 @@ jobs:
     timeout-minutes: 20
     strategy:
       fail-fast: false
+      max-parallel: 4
       matrix:
         include:
           - check_name: check-guards
@@ -1389,6 +1394,7 @@ jobs:
     timeout-minutes: 20
     strategy:
       fail-fast: false
+      max-parallel: 4
       matrix:
         include:
           - check_name: check-additional-boundaries-a
@@ -1763,6 +1769,7 @@ jobs:
         shell: bash
     strategy:
       fail-fast: false
+      max-parallel: 2
       matrix: ${{ fromJson(needs.preflight.outputs.checks_windows_matrix) }}
     steps:
       - name: Checkout
@@ -2092,6 +2099,7 @@ jobs:
     timeout-minutes: 20
     strategy:
       fail-fast: false
+      max-parallel: 2
       matrix: ${{ fromJson(needs.preflight.outputs.android_matrix) }}
     steps:
       - name: Checkout
diff --git a/test/scripts/ci-workflow-guards.test.ts b/test/scripts/ci-workflow-guards.test.ts
index dc7b3193ae41..40d56b159e11 100644
--- a/test/scripts/ci-workflow-guards.test.ts
+++ b/test/scripts/ci-workflow-guards.test.ts
@@ -101,6 +101,19 @@ describe("ci workflow guards", () => {
     expect(action).toContain("docs/* | *.md | *.mdx)");
   });
 
+  it("bounds matrix fan-out for runner-registration pressure", () => {
+    const workflow = readCiWorkflow();
+
+    expect(workflow.jobs["checks-fast-core"].strategy["max-parallel"]).toBe(4);
+    expect(workflow.jobs["checks-node-core-test-nondist-shard"].strategy["max-parallel"]).toBe(6);
+    expect(workflow.jobs["checks-fast-plugin-contracts-shard"].strategy["max-parallel"]).toBe(4);
+    expect(workflow.jobs["checks-fast-channel-contracts-shard"].strategy["max-parallel"]).toBe(4);
+    expect(workflow.jobs["check-shard"].strategy["max-parallel"]).toBe(4);
+    expect(workflow.jobs["check-additional-shard"].strategy["max-parallel"]).toBe(4);
+    expect(workflow.jobs["checks-windows"].strategy["max-parallel"]).toBe(2);
+    expect(workflow.jobs.android.strategy["max-parallel"]).toBe(2);
+  });
+
   it("runs the session accessor ratchet as a visible additional check", () => {
     const workflow = readCiWorkflow();
     const additionalJob = workflow.jobs["check-additional-shard"];