diff --git a/.github/workflows/aixgo.yml b/.github/workflows/aixgo.yml
index f87ee1a..27d2037 100644
--- a/.github/workflows/aixgo.yml
+++ b/.github/workflows/aixgo.yml
@@ -91,6 +91,10 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
+          # Floating on purpose, unlike this repo's own workflows: this job
+          # checks out the ADOPTER's repository, so go-version-file would read
+          # their go.mod, not ours. The CLI needs whatever the newest 1.26.x
+          # is; setup-go resolves that from the floating constraint.
           go-version: "1.26"
 
       - name: Install Aixgo CLI
@@ -181,6 +185,10 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
+          # Floating on purpose, unlike this repo's own workflows: this job
+          # checks out the ADOPTER's repository, so go-version-file would read
+          # their go.mod, not ours. The CLI needs whatever the newest 1.26.x
+          # is; setup-go resolves that from the floating constraint.
           go-version: "1.26"
 
       - name: Install Aixgo CLI
diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 394701b..4832479 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -16,15 +16,11 @@ permissions:
 jobs:
   check:
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        go-version: ["1.26"]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: ${{ matrix.go-version }}
+          go-version-file: 'go.mod'
       - run: make check
       - name: Upload coverage reports to Codecov
         uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index fff9342..4ec5527 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -10,15 +10,11 @@ jobs:
     permissions:
       contents: read
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        go-version: ["1.26"]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: ${{ matrix.go-version }}
+          go-version-file: 'go.mod'
       - run: make check
 
   release:
@@ -30,7 +26,7 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: "1.26"
+          go-version-file: 'go.mod'
       - name: Extract release notes
         id: notes
         run: |
diff --git a/.github/workflows/tag-release.yml b/.github/workflows/tag-release.yml
index 8cf50da..e45dd81 100644
--- a/.github/workflows/tag-release.yml
+++ b/.github/workflows/tag-release.yml
@@ -49,7 +49,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: "1.26"
+          go-version-file: 'go.mod'
 
       - name: Verify the release is ready
         env:
diff --git a/go.mod b/go.mod
index 7ad1280..5219384 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,11 @@ module github.com/aixgo-dev/code
 
 go 1.26
 
+// The single Go pin for this repo's own CI: check, release, and
+// tag-release read this file via go-version-file. The reusable workflow
+// floats on "1.26" instead, because it runs in adopter checkouts.
+toolchain go1.26.5
+
 // v0.1.2 was tagged from the wrong commit (the release-prep commit was not yet
 // pulled), so its version strings and workflow pins point at v0.1.1. The tag
 // could not be re-pointed: proxy.golang.org and sum.golang.org had already