diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index fb11ab9c..ede75a91 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -84,6 +84,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/all-versions.bash b/fixtures/all-versions.bash
index 3407b427..831b21d9 100644
--- a/fixtures/all-versions.bash
+++ b/fixtures/all-versions.bash
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 #!/bin/bash
 # shellcheck disable=SC2086,SC2016,SC2046
 # REGENDATA ["bash","all-versions.project"]
@@ -21,7 +21,7 @@ fi
 
 CFG_CABAL_STORE_CACHE=""
 CFG_CABAL_REPO_CACHE=""
-CFG_JOBS="9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
+CFG_JOBS="9.12.1 9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
 CFG_CABAL_UPDATE=false
 
 SCRIPT_NAME=$(basename "$0")
diff --git a/fixtures/all-versions.github b/fixtures/all-versions.github
index 6d404312..f6ef2a67 100644
--- a/fixtures/all-versions.github
+++ b/fixtures/all-versions.github
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This GitHub workflow config has been generated by a script via
 #
 #   haskell-ci 'github' 'all-versions.project'
@@ -33,6 +33,11 @@ jobs:
             compilerVersion: "8.4"
             setup-method: hvr-ppa
             allow-failure: false
+          - compiler: ghc-9.12.0.20241014
+            compilerKind: ghc
+            compilerVersion: 9.12.0.20241014
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.10.1
             compilerKind: ghc
             compilerVersion: 9.10.1
@@ -311,6 +316,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           else
@@ -323,6 +329,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           fi
         env:
@@ -357,7 +364,7 @@ jobs:
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
@@ -385,6 +392,18 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
+          EOF
+          fi
           cat >> $CABAL_CONFIG <<EOF
           program-default-options
             ghc-options: $GHCJOBS +RTS -M3G -RTS
@@ -438,6 +457,9 @@ jobs:
           if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo "    ghc-options: -Werror=missing-methods" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(splitmix)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
diff --git a/fixtures/all-versions.travis b/fixtures/all-versions.travis
index ebfd8285..33adf573 100644
--- a/fixtures/all-versions.travis
+++ b/fixtures/all-versions.travis
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This Travis job script has been generated by a script via
 #
 #   haskell-ci 'travis' 'all-versions.project'
@@ -36,6 +36,9 @@ jobs:
     - compiler: ghcjs-8.4
       addons: {"apt":{"packages":["ghcjs-8.4","cabal-install-3.4","ghc-8.4.4","nodejs"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"},{"sourceline":"deb http://ppa.launchpad.net/hvr/ghcjs/ubuntu jammy main"},{"key_url":"https://deb.nodesource.com/gpgkey/nodesource.gpg.key","sourceline":"deb https://deb.nodesource.com/node_10.x jammy main"}]}}
       os: linux
+    - compiler: ghc-9.12.1
+      addons: {"apt":{"packages":["ghc-9.12.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
+      os: linux
     - compiler: ghc-9.10.1
       addons: {"apt":{"packages":["ghc-9.10.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
       os: linux
@@ -215,6 +218,7 @@ before_install:
   - TEST=--enable-tests
   - BENCH=--enable-benchmarks
   - HEADHACKAGE=false
+  - if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then HEADHACKAGE=true ; fi
   - rm -f $CABALHOME/config
   - |
     echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
@@ -232,6 +236,17 @@ before_install:
     echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
     echo "repository hackage.haskell.org"               >> $CABALHOME/config
     echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
+  - |
+    if $HEADHACKAGE; then
+    echo "repository head.hackage.ghc.haskell.org"                                         >> $CABALHOME/config
+    echo "   url: https://ghc.gitlab.haskell.org/head.hackage/"                            >> $CABALHOME/config
+    echo "   secure: True"                                                                 >> $CABALHOME/config
+    echo "   root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d"  >> $CABALHOME/config
+    echo "              26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329"  >> $CABALHOME/config
+    echo "              f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89"  >> $CABALHOME/config
+    echo "   key-threshold: 3"                                                             >> $CABALHOME/config
+    echo "active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override" >> $CABALHOME/config
+    fi
 install:
   - ${CABAL} --version
   - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
@@ -251,6 +266,10 @@ install:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
@@ -278,6 +297,10 @@ script:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
diff --git a/fixtures/copy-fields-all.github b/fixtures/copy-fields-all.github
index 8adfb7df..c08ea432 100644
--- a/fixtures/copy-fields-all.github
+++ b/fixtures/copy-fields-all.github
@@ -157,6 +157,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/copy-fields-none.github b/fixtures/copy-fields-none.github
index 89ff1e5c..48576a07 100644
--- a/fixtures/copy-fields-none.github
+++ b/fixtures/copy-fields-none.github
@@ -157,6 +157,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/copy-fields-some.github b/fixtures/copy-fields-some.github
index efb9b4b6..c175594d 100644
--- a/fixtures/copy-fields-some.github
+++ b/fixtures/copy-fields-some.github
@@ -157,6 +157,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/doctest-version.bash b/fixtures/doctest-version.bash
index df9f2475..6c23e1c0 100644
--- a/fixtures/doctest-version.bash
+++ b/fixtures/doctest-version.bash
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 #!/bin/bash
 # shellcheck disable=SC2086,SC2016,SC2046
 # REGENDATA ["--doctest","--doctest-version=^>=0.20","bash","doctest-version.project"]
@@ -21,7 +21,7 @@ fi
 
 CFG_CABAL_STORE_CACHE=""
 CFG_CABAL_REPO_CACHE=""
-CFG_JOBS="9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
+CFG_JOBS="9.12.1 9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
 CFG_CABAL_UPDATE=false
 
 SCRIPT_NAME=$(basename "$0")
diff --git a/fixtures/doctest-version.github b/fixtures/doctest-version.github
index 195d4277..bb6e8ce7 100644
--- a/fixtures/doctest-version.github
+++ b/fixtures/doctest-version.github
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This GitHub workflow config has been generated by a script via
 #
 #   haskell-ci '--doctest' '--doctest-version=^>=0.20' 'github' 'doctest-version.project'
@@ -33,6 +33,11 @@ jobs:
             compilerVersion: "8.4"
             setup-method: hvr-ppa
             allow-failure: false
+          - compiler: ghc-9.12.0.20241014
+            compilerKind: ghc
+            compilerVersion: 9.12.0.20241014
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.10.1
             compilerKind: ghc
             compilerVersion: 9.10.1
@@ -311,6 +316,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           else
@@ -323,6 +329,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           fi
         env:
@@ -357,7 +364,7 @@ jobs:
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
@@ -385,6 +392,18 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
+          EOF
+          fi
           cat >> $CABAL_CONFIG <<EOF
           program-default-options
             ghc-options: $GHCJOBS +RTS -M3G -RTS
@@ -453,6 +472,9 @@ jobs:
           if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo "    ghc-options: -Werror=missing-methods" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(splitmix)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
diff --git a/fixtures/doctest-version.travis b/fixtures/doctest-version.travis
index b8d2ebfa..d82fac03 100644
--- a/fixtures/doctest-version.travis
+++ b/fixtures/doctest-version.travis
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This Travis job script has been generated by a script via
 #
 #   haskell-ci '--doctest' '--doctest-version=^>=0.20' 'travis' 'doctest-version.project'
@@ -36,6 +36,9 @@ jobs:
     - compiler: ghcjs-8.4
       addons: {"apt":{"packages":["ghcjs-8.4","cabal-install-3.4","ghc-8.4.4","nodejs"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"},{"sourceline":"deb http://ppa.launchpad.net/hvr/ghcjs/ubuntu jammy main"},{"key_url":"https://deb.nodesource.com/gpgkey/nodesource.gpg.key","sourceline":"deb https://deb.nodesource.com/node_10.x jammy main"}]}}
       os: linux
+    - compiler: ghc-9.12.1
+      addons: {"apt":{"packages":["ghc-9.12.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
+      os: linux
     - compiler: ghc-9.10.1
       addons: {"apt":{"packages":["ghc-9.10.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
       os: linux
@@ -215,6 +218,7 @@ before_install:
   - TEST=--enable-tests
   - BENCH=--enable-benchmarks
   - HEADHACKAGE=false
+  - if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then HEADHACKAGE=true ; fi
   - rm -f $CABALHOME/config
   - |
     echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
@@ -232,6 +236,17 @@ before_install:
     echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
     echo "repository hackage.haskell.org"               >> $CABALHOME/config
     echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
+  - |
+    if $HEADHACKAGE; then
+    echo "repository head.hackage.ghc.haskell.org"                                         >> $CABALHOME/config
+    echo "   url: https://ghc.gitlab.haskell.org/head.hackage/"                            >> $CABALHOME/config
+    echo "   secure: True"                                                                 >> $CABALHOME/config
+    echo "   root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d"  >> $CABALHOME/config
+    echo "              26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329"  >> $CABALHOME/config
+    echo "              f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89"  >> $CABALHOME/config
+    echo "   key-threshold: 3"                                                             >> $CABALHOME/config
+    echo "active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override" >> $CABALHOME/config
+    fi
 install:
   - ${CABAL} --version
   - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
@@ -252,6 +267,10 @@ install:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
@@ -279,6 +298,10 @@ script:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
diff --git a/fixtures/doctest.bash b/fixtures/doctest.bash
index 829e0b86..d9bf8a24 100644
--- a/fixtures/doctest.bash
+++ b/fixtures/doctest.bash
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 #!/bin/bash
 # shellcheck disable=SC2086,SC2016,SC2046
 # REGENDATA ["--doctest","bash","doctest.project"]
@@ -21,7 +21,7 @@ fi
 
 CFG_CABAL_STORE_CACHE=""
 CFG_CABAL_REPO_CACHE=""
-CFG_JOBS="9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
+CFG_JOBS="9.12.1 9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
 CFG_CABAL_UPDATE=false
 
 SCRIPT_NAME=$(basename "$0")
diff --git a/fixtures/doctest.github b/fixtures/doctest.github
index 115119dc..d1c128c5 100644
--- a/fixtures/doctest.github
+++ b/fixtures/doctest.github
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This GitHub workflow config has been generated by a script via
 #
 #   haskell-ci '--doctest' 'github' 'doctest.project'
@@ -33,6 +33,11 @@ jobs:
             compilerVersion: "8.4"
             setup-method: hvr-ppa
             allow-failure: false
+          - compiler: ghc-9.12.0.20241014
+            compilerKind: ghc
+            compilerVersion: 9.12.0.20241014
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.10.1
             compilerKind: ghc
             compilerVersion: 9.10.1
@@ -311,6 +316,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           else
@@ -323,6 +329,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           fi
         env:
@@ -357,7 +364,7 @@ jobs:
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
@@ -385,6 +392,18 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
+          EOF
+          fi
           cat >> $CABAL_CONFIG <<EOF
           program-default-options
             ghc-options: $GHCJOBS +RTS -M3G -RTS
@@ -453,6 +472,9 @@ jobs:
           if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo "    ghc-options: -Werror=missing-methods" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(splitmix)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
diff --git a/fixtures/doctest.travis b/fixtures/doctest.travis
index 448def00..66f43032 100644
--- a/fixtures/doctest.travis
+++ b/fixtures/doctest.travis
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This Travis job script has been generated by a script via
 #
 #   haskell-ci '--doctest' 'travis' 'doctest.project'
@@ -36,6 +36,9 @@ jobs:
     - compiler: ghcjs-8.4
       addons: {"apt":{"packages":["ghcjs-8.4","cabal-install-3.4","ghc-8.4.4","nodejs"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"},{"sourceline":"deb http://ppa.launchpad.net/hvr/ghcjs/ubuntu jammy main"},{"key_url":"https://deb.nodesource.com/gpgkey/nodesource.gpg.key","sourceline":"deb https://deb.nodesource.com/node_10.x jammy main"}]}}
       os: linux
+    - compiler: ghc-9.12.1
+      addons: {"apt":{"packages":["ghc-9.12.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
+      os: linux
     - compiler: ghc-9.10.1
       addons: {"apt":{"packages":["ghc-9.10.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
       os: linux
@@ -215,6 +218,7 @@ before_install:
   - TEST=--enable-tests
   - BENCH=--enable-benchmarks
   - HEADHACKAGE=false
+  - if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then HEADHACKAGE=true ; fi
   - rm -f $CABALHOME/config
   - |
     echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
@@ -232,6 +236,17 @@ before_install:
     echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
     echo "repository hackage.haskell.org"               >> $CABALHOME/config
     echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
+  - |
+    if $HEADHACKAGE; then
+    echo "repository head.hackage.ghc.haskell.org"                                         >> $CABALHOME/config
+    echo "   url: https://ghc.gitlab.haskell.org/head.hackage/"                            >> $CABALHOME/config
+    echo "   secure: True"                                                                 >> $CABALHOME/config
+    echo "   root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d"  >> $CABALHOME/config
+    echo "              26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329"  >> $CABALHOME/config
+    echo "              f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89"  >> $CABALHOME/config
+    echo "   key-threshold: 3"                                                             >> $CABALHOME/config
+    echo "active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override" >> $CABALHOME/config
+    fi
 install:
   - ${CABAL} --version
   - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
@@ -252,6 +267,10 @@ install:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
@@ -279,6 +298,10 @@ script:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
diff --git a/fixtures/enabled-jobs.bash b/fixtures/enabled-jobs.bash
index eecb63f8..0911252f 100644
--- a/fixtures/enabled-jobs.bash
+++ b/fixtures/enabled-jobs.bash
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Bash script for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 #!/bin/bash
 # shellcheck disable=SC2086,SC2016,SC2046
 # REGENDATA ["--enabled-jobs=>=8","bash","enabled-jobs.project"]
@@ -21,7 +21,7 @@ fi
 
 CFG_CABAL_STORE_CACHE=""
 CFG_CABAL_REPO_CACHE=""
-CFG_JOBS="9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
+CFG_JOBS="9.12.1 9.10.1 9.8.2 9.8.1 9.6.6 9.6.5 9.6.4 9.6.3 9.6.2 9.6.1 9.4.8 9.4.7 9.4.6 9.4.5 9.4.4 9.4.3 9.4.2 9.4.1 9.2.8 9.2.7 9.2.6 9.2.5 9.2.4 9.2.3 9.2.2 9.2.1 9.0.2 9.0.1 8.10.7 8.10.6 8.10.5 8.10.4 8.10.3 8.10.2 8.10.1 8.8.4 8.8.3 8.8.2 8.8.1 8.6.5 8.6.4 8.6.3 8.6.2 8.6.1 8.4.4 8.4.3 8.4.2 8.4.1 8.2.2 8.2.1 8.0.2 8.0.1"
 CFG_CABAL_UPDATE=false
 
 SCRIPT_NAME=$(basename "$0")
diff --git a/fixtures/enabled-jobs.github b/fixtures/enabled-jobs.github
index 78bb6cc1..f7edad73 100644
--- a/fixtures/enabled-jobs.github
+++ b/fixtures/enabled-jobs.github
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating GitHub config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This GitHub workflow config has been generated by a script via
 #
 #   haskell-ci '--enabled-jobs=>=8' 'github' 'enabled-jobs.project'
@@ -33,6 +33,11 @@ jobs:
             compilerVersion: "8.4"
             setup-method: hvr-ppa
             allow-failure: false
+          - compiler: ghc-9.12.0.20241014
+            compilerKind: ghc
+            compilerVersion: 9.12.0.20241014
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.10.1
             compilerKind: ghc
             compilerVersion: 9.10.1
@@ -311,6 +316,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           else
@@ -323,6 +329,7 @@ jobs:
             mkdir -p "$HOME/.ghcup/bin"
             curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
             chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
             "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
           fi
         env:
@@ -357,7 +364,7 @@ jobs:
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
@@ -385,6 +392,18 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
+          EOF
+          fi
           cat >> $CABAL_CONFIG <<EOF
           program-default-options
             ghc-options: $GHCJOBS +RTS -M3G -RTS
@@ -438,6 +457,9 @@ jobs:
           if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo "    ghc-options: -Werror=missing-methods" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(splitmix)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
diff --git a/fixtures/enabled-jobs.travis b/fixtures/enabled-jobs.travis
index da904709..5d5e348d 100644
--- a/fixtures/enabled-jobs.travis
+++ b/fixtures/enabled-jobs.travis
@@ -1,5 +1,5 @@
 # SUCCESS
-# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 ghcjs-8.4
+# *INFO* Generating Travis-CI config for testing for GHC versions: 8.0.1 8.0.2 8.2.1 8.2.2 8.4.1 8.4.2 8.4.3 8.4.4 8.6.1 8.6.2 8.6.3 8.6.4 8.6.5 8.8.1 8.8.2 8.8.3 8.8.4 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7 9.0.1 9.0.2 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.4.6 9.4.7 9.4.8 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.8.1 9.8.2 9.10.1 9.12.1 ghcjs-8.4
 # This Travis job script has been generated by a script via
 #
 #   haskell-ci '--enabled-jobs=>=8' 'travis' 'enabled-jobs.project'
@@ -36,6 +36,9 @@ jobs:
     - compiler: ghcjs-8.4
       addons: {"apt":{"packages":["ghcjs-8.4","cabal-install-3.4","ghc-8.4.4","nodejs"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"},{"sourceline":"deb http://ppa.launchpad.net/hvr/ghcjs/ubuntu jammy main"},{"key_url":"https://deb.nodesource.com/gpgkey/nodesource.gpg.key","sourceline":"deb https://deb.nodesource.com/node_10.x jammy main"}]}}
       os: linux
+    - compiler: ghc-9.12.1
+      addons: {"apt":{"packages":["ghc-9.12.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
+      os: linux
     - compiler: ghc-9.10.1
       addons: {"apt":{"packages":["ghc-9.10.1","cabal-install-3.12.1.0"],"sources":[{"key_url":"https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x063dab2bdc0b3f9fcebc378bff3aeacef6f88286","sourceline":"deb http://ppa.launchpad.net/hvr/ghc/ubuntu jammy main"}]}}
       os: linux
@@ -215,6 +218,7 @@ before_install:
   - TEST=--enable-tests
   - BENCH=--enable-benchmarks
   - HEADHACKAGE=false
+  - if [ $((! GHCJSARITH && HCNUMVER >= 91200)) -ne 0 ] ; then HEADHACKAGE=true ; fi
   - rm -f $CABALHOME/config
   - |
     echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
@@ -232,6 +236,17 @@ before_install:
     echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
     echo "repository hackage.haskell.org"               >> $CABALHOME/config
     echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
+  - |
+    if $HEADHACKAGE; then
+    echo "repository head.hackage.ghc.haskell.org"                                         >> $CABALHOME/config
+    echo "   url: https://ghc.gitlab.haskell.org/head.hackage/"                            >> $CABALHOME/config
+    echo "   secure: True"                                                                 >> $CABALHOME/config
+    echo "   root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d"  >> $CABALHOME/config
+    echo "              26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329"  >> $CABALHOME/config
+    echo "              f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89"  >> $CABALHOME/config
+    echo "   key-threshold: 3"                                                             >> $CABALHOME/config
+    echo "active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override" >> $CABALHOME/config
+    fi
 install:
   - ${CABAL} --version
   - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
@@ -251,6 +266,10 @@ install:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
@@ -278,6 +297,10 @@ script:
   - if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo 'package splitmix' >> cabal.project ; fi
   - "if [ $((GHCJSARITH || ! GHCJSARITH && HCNUMVER >= 80200)) -ne 0 ] ; then echo '  ghc-options: -Werror=missing-methods' >> cabal.project ; fi"
   - ""
+  - |
+    if $HEADHACKAGE; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> $CABALHOME/config
+    fi
   - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(splitmix)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
   - cat cabal.project || true
   - cat cabal.project.local || true
diff --git a/fixtures/fail-versions.github b/fixtures/fail-versions.github
index b40465a0..7698a18f 100644
--- a/fixtures/fail-versions.github
+++ b/fixtures/fail-versions.github
@@ -157,6 +157,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/irc-channels.github b/fixtures/irc-channels.github
index f9069877..7dae3448 100644
--- a/fixtures/irc-channels.github
+++ b/fixtures/irc-channels.github
@@ -184,6 +184,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/psql.github b/fixtures/psql.github
index 79ff3b85..3fad05e7 100644
--- a/fixtures/psql.github
+++ b/fixtures/psql.github
@@ -163,6 +163,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/fixtures/travis-patch.github b/fixtures/travis-patch.github
index a17d6ed0..e9673bb2 100644
--- a/fixtures/travis-patch.github
+++ b/fixtures/travis-patch.github
@@ -157,6 +157,7 @@ jobs:
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
           "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
         env:
diff --git a/haskell-ci.cabal b/haskell-ci.cabal
index a6f74bdc..125f3aab 100644
--- a/haskell-ci.cabal
+++ b/haskell-ci.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               haskell-ci
-version:            0.19.20240708
+version:            0.19.20241021
 synopsis:           Cabal package script generator for Travis-CI
 description:
   Script generator (@haskell-ci@) for
diff --git a/src/HaskellCI/Compiler.hs b/src/HaskellCI/Compiler.hs
index cd9f3e5e..e4f02dc8 100644
--- a/src/HaskellCI/Compiler.hs
+++ b/src/HaskellCI/Compiler.hs
@@ -142,6 +142,7 @@ knownGhcVersions = fmap mkVersion
     , [9,6,1],  [9,6,2],  [9,6,3], [9,6,4], [9,6,5], [9,6,6]
     , [9,8,1],  [9,8,2]
     , [9,10,1]
+    , [9,12,1]
     ]
 
 knownGhcjsVersions :: [Version]
@@ -184,7 +185,7 @@ dispCabalVersion :: Maybe Version -> String
 dispCabalVersion = maybe "head" C.prettyShow
 
 ghcAlpha :: Maybe (Version, Version)
-ghcAlpha = Nothing -- Just (mkVersion [9,10,1], mkVersion [9,10,0,20240426])
+ghcAlpha = Just (mkVersion [9,12,1], mkVersion [9,12,0,20241014])
 
 -- | GHC HEAD, and versions specified by head.hackage option.
 usesHeadHackage