From d4301132945558a4dcb12a3df61c02496018c1fb Mon Sep 17 00:00:00 2001
From: Jesper Terkelsen <jete@monta.com>
Date: Thu, 4 Jun 2026 22:28:45 +0200
Subject: [PATCH] ci(pull-request-kotlin): persist Gradle build-cache across
 runs via split restore/save [NO-JIRA]
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The test job recompiled (~150s of KSP + Kotlin, main+test) on every run.
Dependencies were cached, but setup-java's built-in 'gradle' cache keys on the
gradle files and only saves on a cache MISS — so Gradle's build-cache (compiled
task output) froze at first save and never accumulated, leaving every run to
recompile from scratch.

Switch to the split restore/save pattern and save on every run under a
per-commit key, so the build-cache persists and unchanged KSP/Kotlin output
returns FROM-CACHE instead of recompiling. The Sonar cache had the same
freeze-on-fixed-key problem and gets the same treatment.

Cache key is branch-scoped with a shared fallback: a PR restores its own
branch's latest cache first (closest source -> best build-cache hit rate),
else the most recent run. Caches are isolated per repository automatically
(GitHub + runs-on), so no repo name is needed in the key. Saves run on
always() so compiled output is cached even when tests fail.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/pull-request-kotlin.yml | 37 ++++++++++++++++++++---
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/pull-request-kotlin.yml b/.github/workflows/pull-request-kotlin.yml
index 6ca4a46..7b896af 100644
--- a/.github/workflows/pull-request-kotlin.yml
+++ b/.github/workflows/pull-request-kotlin.yml
@@ -90,14 +90,27 @@ jobs:
         with:
           distribution: corretto
           java-version: ${{ inputs.java-version }}
-          cache: 'gradle'
-      - name: Cache SonarCloud packages
-        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+      - name: Restore Gradle cache
+        id: gradle-cache
+        uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ github.head_ref }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-${{ github.head_ref }}-
+            ${{ runner.os }}-gradle-
+      - name: Restore SonarCloud cache
+        id: sonar-cache
         if: ${{ !inputs.skip-sonar }}
+        uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
         with:
           path: ~/.sonar/cache
-          key: ${{ runner.os }}-sonar
-          restore-keys: ${{ runner.os }}-sonar
+          key: ${{ runner.os }}-sonar-${{ github.head_ref }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-sonar-${{ github.head_ref }}-
+            ${{ runner.os }}-sonar-
       - name: Run linter
         env:
           GHL_USERNAME: ${{ secrets.GHL_USERNAME }}
@@ -158,3 +171,17 @@ jobs:
             **/build/test-results/**/*.xml
             **/build/test-results/**/*.trx
             **/build/test-results/**/*.json
+      - name: Save Gradle cache
+        if: ${{ always() && steps.gradle-cache.outputs.cache-hit != 'true' }}
+        uses: actions/cache/save@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ github.head_ref }}-${{ github.sha }}
+      - name: Save SonarCloud cache
+        if: ${{ always() && !inputs.skip-sonar && steps.sonar-cache.outputs.cache-hit != 'true' }}
+        uses: actions/cache/save@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+        with:
+          path: ~/.sonar/cache
+          key: ${{ runner.os }}-sonar-${{ github.head_ref }}-${{ github.sha }}