From f8c110562ad95af6d64e912be5be96ca9a8af957 Mon Sep 17 00:00:00 2001
From: Dorian Scheidt <dorian.scheidt@gmail.com>
Date: Wed, 12 Aug 2026 14:06:36 -0500
Subject: [PATCH] RUE-1476: cache the dotslash buck2 download in the jobs that
 missed it

Nine CI jobs restore the dotslash-downloaded buck2 binary from the actions
cache; fmt and remote-execution did not, and neither did cache-probe's probe
job while its sibling rue-program-warm did. Those jobs re-fetch buck2 from the
GitHub releases CDN on every run, so a transient CDN failure fails them before
any Rue code is exercised -- which is what evicted a PR from the merge queue
today, where a flake costs a whole queue cycle rather than a re-run.

The step is the one clippy already carries, unchanged. All three jobs are
single-platform ubuntu, so they take the existing dotslash-linux-x64 key
rather than the matrix-keyed form the multi-OS jobs use.
---
 .github/workflows/cache-probe.yml | 11 +++++++++++
 .github/workflows/ci.yml          | 24 ++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/.github/workflows/cache-probe.yml b/.github/workflows/cache-probe.yml
index 40196616f..49b45bc60 100644
--- a/.github/workflows/cache-probe.yml
+++ b/.github/workflows/cache-probe.yml
@@ -43,6 +43,17 @@ jobs:
       - name: Install dotslash
         uses: facebook/install-dotslash@v2
 
+      # The buck2 binary itself, not build artifacts: this job deliberately
+      # clears buck-out and rebuilds cold, but re-downloading buck2 from the
+      # releases CDN is a network dependency the probe does not exist to test.
+      - name: Cache dotslash artifacts
+        uses: actions/cache@v5
+        with:
+          path: ~/.cache/dotslash
+          key: dotslash-linux-x64-${{ hashFiles('buck2') }}
+          restore-keys: |
+            dotslash-linux-x64-
+
       - name: Guard — secret present
         env:
           KEY: ${{ secrets.BUILDBUDDY_API_KEY }}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2134d63ac..7dc2e6bfd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,6 +33,18 @@ jobs:
       - name: Install dotslash
         uses: facebook/install-dotslash@v2  # pinned: the moving `latest` branch broke macOS runners (sha256sum flags) on 2026-06-18
 
+      # Cache the dotslash-downloaded buck2 binary (see the `test` job for the
+      # rationale on which paths are worth caching).
+      - name: Cache dotslash artifacts
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/.cache/dotslash
+            ~/Library/Caches/dotslash
+          key: dotslash-linux-x64-${{ hashFiles('buck2') }}
+          restore-keys: |
+            dotslash-linux-x64-
+
       - name: Check formatting
         # Every crate emits its own `<name>-fmt-check` test from the
         # rue_crate/rue_binary macros (RUE-1153), so coverage follows the
@@ -148,6 +160,18 @@ jobs:
       - name: Install dotslash
         uses: facebook/install-dotslash@v2
 
+      # Cache the dotslash-downloaded buck2 binary (see the `test` job for the
+      # rationale on which paths are worth caching).
+      - name: Cache dotslash artifacts
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/.cache/dotslash
+            ~/Library/Caches/dotslash
+          key: dotslash-linux-x64-${{ hashFiles('buck2') }}
+          restore-keys: |
+            dotslash-linux-x64-
+
       - name: Require and provision remote execution
         env:
           BUILDBUDDY_API_KEY: ${{ secrets.BUILDBUDDY_API_KEY }}