diff --git a/.github/workflows/anchor.yml b/.github/workflows/anchor.yml
index 3f8e36133..1de8dcf8b 100644
--- a/.github/workflows/anchor.yml
+++ b/.github/workflows/anchor.yml
@@ -138,7 +138,14 @@ jobs:
       - uses: heyAyushh/setup-anchor@v4.999
         with:
           anchor-version: 1.0.0
-          solana-cli-version: stable
+          # Pinned to 3.1.10 (not `stable`) because heyAyushh/setup-anchor's
+          # `stable` resolver intermittently returns an empty version string,
+          # which makes the action curl https://release.anza.xyz/v/install and
+          # 404. 3.1.10 is the version recommended by Anchor 1.0.0's release
+          # notes and pinned by Anchor's own CI in 1.0.0-rc.5+. Bump in lockstep
+          # with anchor-version above. See upstream issue tracking the brittle
+          # `stable` behaviour.
+          solana-cli-version: 3.1.10
       - name: Install Surfpool
         run: curl -sL https://run.surfpool.run/ | bash
       - name: Display Versions
diff --git a/.github/workflows/native.yml b/.github/workflows/native.yml
index 7799128ab..f9ce77b08 100644
--- a/.github/workflows/native.yml
+++ b/.github/workflows/native.yml
@@ -222,7 +222,16 @@ jobs:
       - name: Setup Solana Stable
         uses: heyAyushh/setup-solana@v5.9
         with:
-          solana-cli-version: stable
+          # Pinned to 3.1.10 (not `stable`) because heyAyushh/setup-solana's
+          # `stable` resolver intermittently returns an empty version string,
+          # which makes the action curl https://release.anza.xyz/v/install and
+          # 404. 3.1.10 is the version recommended by Anchor 1.0.0's release
+          # notes; we use it here too to keep the matrix consistent across
+          # frameworks. The `beta` step below intentionally stays floating —
+          # it's the channel-tracking job and is already marked
+          # continue-on-error. See upstream issue tracking the brittle `stable`
+          # behaviour.
+          solana-cli-version: 3.1.10
       - name: Build and Test with Stable
         run: |
           source build_and_test.sh
diff --git a/.github/workflows/pinocchio.yml b/.github/workflows/pinocchio.yml
index f63582b14..84ac3bc11 100644
--- a/.github/workflows/pinocchio.yml
+++ b/.github/workflows/pinocchio.yml
@@ -222,7 +222,16 @@ jobs:
       - name: Setup Solana Stable
         uses: heyAyushh/setup-solana@v5.9
         with:
-          solana-cli-version: stable
+          # Pinned to 3.1.10 (not `stable`) because heyAyushh/setup-solana's
+          # `stable` resolver intermittently returns an empty version string,
+          # which makes the action curl https://release.anza.xyz/v/install and
+          # 404. 3.1.10 is the version recommended by Anchor 1.0.0's release
+          # notes; we use it here too to keep the matrix consistent across
+          # frameworks. The `beta` step below intentionally stays floating —
+          # it's the channel-tracking job and is already marked
+          # continue-on-error. See upstream issue tracking the brittle `stable`
+          # behaviour.
+          solana-cli-version: 3.1.10
       - name: Build and Test with Stable
         run: |
           source build_and_test.sh
diff --git a/.github/workflows/quasar.yml b/.github/workflows/quasar.yml
index 25e604b64..ff172be4e 100644
--- a/.github/workflows/quasar.yml
+++ b/.github/workflows/quasar.yml
@@ -197,7 +197,13 @@ jobs:
       - name: Setup Solana Stable
         uses: heyAyushh/setup-solana@v5.9
         with:
-          solana-cli-version: stable
+          # Pinned to 3.1.10 (not `stable`) because heyAyushh/setup-solana's
+          # `stable` resolver intermittently returns an empty version string,
+          # which makes the action curl https://release.anza.xyz/v/install and
+          # 404. 3.1.10 is the version recommended by Anchor 1.0.0's release
+          # notes; using it here keeps the matrix consistent across frameworks.
+          # See upstream issue tracking the brittle `stable` behaviour.
+          solana-cli-version: 3.1.10
       - name: Install Quasar CLI
         # Pinned to quasar rev 3d6fb0d8 (the HEAD this migration was written
         # against, immediately after PRs #195 + #196). The next merged PR