diff --git a/.github/scripts/supply-chain-policy.test.mjs b/.github/scripts/supply-chain-policy.test.mjs
index 50b55b16a2..238899c785 100644
--- a/.github/scripts/supply-chain-policy.test.mjs
+++ b/.github/scripts/supply-chain-policy.test.mjs
@@ -12,6 +12,20 @@ async function workflows() {
   );
 }
 
+// 같은 저장소의 로컬 액션·reusable workflow 는 uses 대상이 이 저장소의 리비전이라
+// 고정 대상이 아니다. 그 밖은 전부 40자리 commit SHA 여야 한다.
+function isLocalReference(reference) {
+    return reference.startsWith("./");
+}
+
+function isPinnedToCommit(reference) {
+    return /@[0-9a-f]{40}$/.test(reference);
+}
+
+function actionReferences(source) {
+    return [...source.matchAll(/^\s*(?:-\s+)?uses:\s*(\S+)/gm)].map((match) => match[1]);
+}
+
 function requiresGradleSetup(source) {
   return source.includes('./gradlew') || /uses:\s*gradle\/actions\/setup-gradle@/.test(source);
 }
@@ -28,6 +42,65 @@ test('recognizes direct and script-delegated Gradle workflows', () => {
   );
 });
 
+test('recognizes floating action references that the pinning policy must reject', () => {
+    // 정책이 실제로 무엇을 막는지 fixture 로 고정한다 — 태그·브랜치·짧은 SHA 는 전부
+    // 사후에 다른 코드로 바뀔 수 있다.
+    assert.equal(isPinnedToCommit('actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1'), true);
+    assert.equal(isPinnedToCommit('actions/checkout@v7'), false);
+    assert.equal(isPinnedToCommit('ScaCap/action-ktlint@master'), false);
+    assert.equal(isPinnedToCommit('actions/checkout@3d3c42e'), false);
+    assert.equal(isLocalReference('./.github/actions/setup-ci-config'), true);
+    assert.equal(isLocalReference('actions/checkout@v7'), false);
+});
+
+test('every third-party action is pinned to an immutable commit SHA', async () => {
+    const unpinned = [];
+    for (const [name, source] of await workflows()) {
+        for (const reference of actionReferences(source)) {
+            if (isLocalReference(reference) || isPinnedToCommit(reference)) {
+                continue;
+            }
+            unpinned.push(`${name}: ${reference}`);
+        }
+    }
+
+    assert.deepEqual(unpinned, []);
+});
+
+test('every pinned action records the release it was pinned from', async () => {
+    // SHA 만 있으면 무엇을 쓰고 있는지 사람이 읽을 수 없고 Dependabot 갱신도 대조가 안 된다.
+    const undocumented = [];
+    for (const [name, source] of await workflows()) {
+        for (const line of source.split('\n')) {
+            const match = /^\s*(?:-\s+)?uses:\s*(\S+@[0-9a-f]{40})(.*)$/.exec(line);
+            if (match && !/^\s*#\s*v?\d/.test(match[2])) {
+                undocumented.push(`${name}: ${match[1]}`);
+            }
+        }
+    }
+
+    assert.deepEqual(undocumented, []);
+});
+
+test('composite actions in this repository pin their own dependencies', async () => {
+    const directory = new URL('../actions/', import.meta.url);
+    const names = await readdir(directory);
+    for (const name of names) {
+        let source;
+        try {
+            source = await readFile(new URL(`${name}/action.yml`, directory), 'utf8');
+        } catch {
+            continue;
+        }
+        for (const reference of actionReferences(source)) {
+            assert.ok(
+                isLocalReference(reference) || isPinnedToCommit(reference),
+                `${name} uses an unpinned action: ${reference}`,
+            );
+        }
+    }
+});
+
 test('every workflow that runs the Gradle wrapper uses the pinned setup-gradle action', async () => {
   const gradleWorkflows = (await workflows()).filter(([, source]) => requiresGradleSetup(source));
   assert.ok(gradleWorkflows.length > 0);
diff --git a/.github/workflows/android-managed-device.yml b/.github/workflows/android-managed-device.yml
index 43deb621c2..bf4732e2c5 100644
--- a/.github/workflows/android-managed-device.yml
+++ b/.github/workflows/android-managed-device.yml
@@ -21,10 +21,10 @@ jobs:
     timeout-minutes: 45
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Set up JDK
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: temurin
           java-version: "21"
@@ -54,7 +54,7 @@ jobs:
 
       - name: Upload androidTest reports and failure evidence
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: android-managed-device-results-${{ github.run_attempt }}
           if-no-files-found: warn
diff --git a/.github/workflows/auto-close-issue.yml b/.github/workflows/auto-close-issue.yml
index c4757f728e..5fbc8ea33a 100644
--- a/.github/workflows/auto-close-issue.yml
+++ b/.github/workflows/auto-close-issue.yml
@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Close issues referenced by close keywords
-        uses: actions/github-script@v9
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         with:
           script: |
             const pr = context.payload.pull_request;
diff --git a/.github/workflows/conflict-label.yml b/.github/workflows/conflict-label.yml
index b6f13c0774..9cede9c9a9 100644
--- a/.github/workflows/conflict-label.yml
+++ b/.github/workflows/conflict-label.yml
@@ -35,7 +35,7 @@ jobs:
     timeout-minutes: 10
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
 
diff --git a/.github/workflows/dependency-audit.yml b/.github/workflows/dependency-audit.yml
index ec30568ed5..d984415e66 100644
--- a/.github/workflows/dependency-audit.yml
+++ b/.github/workflows/dependency-audit.yml
@@ -29,12 +29,12 @@ jobs:
       REPORT_DIR: build/reports/dependency-audit
     steps:
       - name: Clone default branch
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: 'temurin'
           java-version: '21'
@@ -124,7 +124,7 @@ jobs:
 
       - name: Upload machine-readable audit evidence
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: android-dependency-audit
           path: ${{ env.REPORT_DIR }}
diff --git a/.github/workflows/firebase-wif-canary.yml b/.github/workflows/firebase-wif-canary.yml
index 1768b59854..a951ad8bc8 100644
--- a/.github/workflows/firebase-wif-canary.yml
+++ b/.github/workflows/firebase-wif-canary.yml
@@ -66,7 +66,7 @@ jobs:
     steps:
       # google-github-actions/auth가 ADC 파일을 안전하게 만들려면 checkout이 먼저 실행돼야 한다.
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare Firebase release notes
         env:
@@ -81,7 +81,7 @@ jobs:
           cat "$RELEASE_NOTES_FILE" >> "$GITHUB_STEP_SUMMARY"
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: temurin
           java-version: '21'
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index ae660db121..4feb9e195f 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -18,10 +18,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: 'temurin'
           java-version: '21'
@@ -58,10 +58,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: 'temurin'
           java-version: '21'
diff --git a/.github/workflows/mock-cleanup-check.yml b/.github/workflows/mock-cleanup-check.yml
index f172897a70..1e20e76e47 100644
--- a/.github/workflows/mock-cleanup-check.yml
+++ b/.github/workflows/mock-cleanup-check.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Check for MOCK_CLEANUP markers
         run: |
diff --git a/.github/workflows/release-distribution.yml b/.github/workflows/release-distribution.yml
index 3f7e737ab4..c2e38f4b9f 100644
--- a/.github/workflows/release-distribution.yml
+++ b/.github/workflows/release-distribution.yml
@@ -32,7 +32,7 @@ jobs:
       # 이 job 은 release keystore·Firebase service account 를 받는다. 트리거가 push: [main] 하나여서
       # ref 가 main 으로 고정되므로, 예전의 수동 실행용 브랜치 가드는 더 방어할 대상이 없어 제거했다.
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Load release metadata from main PR
         env:
@@ -57,7 +57,7 @@ jobs:
           cat "$RELEASE_NOTES_FILE" >> "$GITHUB_STEP_SUMMARY"
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: 'temurin'
           java-version: '21'
diff --git a/.github/workflows/release-scope.yml b/.github/workflows/release-scope.yml
index f7bb1f08ac..cb510f199b 100644
--- a/.github/workflows/release-scope.yml
+++ b/.github/workflows/release-scope.yml
@@ -30,7 +30,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone release candidate
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           ref: ${{ github.event.pull_request.head.sha || 'develop' }}
           fetch-depth: 0
@@ -53,7 +53,7 @@ jobs:
             "$RELEASE_SCOPE_PATH"
 
       - name: Fill release sections on the PR body
-        uses: actions/github-script@v9
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         env:
           RELEASE_SCOPE_PATH: ${{ runner.temp }}/afternote-release-scope/scope.json
           RELEASE_PR_NUMBER: ${{ github.event.pull_request.number || inputs.pull_request_number }}
diff --git a/.github/workflows/repository-quality.yml b/.github/workflows/repository-quality.yml
index 527fd4fa3f..bc5689b92a 100644
--- a/.github/workflows/repository-quality.yml
+++ b/.github/workflows/repository-quality.yml
@@ -20,7 +20,7 @@ jobs:
     timeout-minutes: 3
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Install actionlint
         env:
diff --git a/.github/workflows/screenshot.yml b/.github/workflows/screenshot.yml
index d8ff1506f6..c5282623d3 100644
--- a/.github/workflows/screenshot.yml
+++ b/.github/workflows/screenshot.yml
@@ -18,16 +18,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       # docker buildx + gha cache 로 Dockerfile.screenshot 빌드.
       # 동일 이미지에서 baseline 생성·검증을 수행해 anti-aliasing/font/scale 등 host 환경 차이 root fix.
       # Dockerfile 변경 없으면 cache 재사용 — 분당 단위 추가 비용.
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v4
+        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
 
       - name: Build screenshot image
-        uses: docker/build-push-action@v7
+        uses: docker/build-push-action@53b7df96c91f9c12dcc8a07bcb9ccacbed38856a # v7.3.0
         with:
           context: .
           file: Dockerfile.screenshot
@@ -74,7 +74,7 @@ jobs:
       # 실패 시 diff/rendered 이미지를 artifact 로 업로드 — 본인이 다운로드해 시각 차이 확인 가능
       - name: Upload screenshot diff on failure
         if: failure()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: screenshot-test-results
           path: |
@@ -89,7 +89,7 @@ jobs:
       # 같은 PR 의 재실행에서는 기존 코멘트를 update (marker 로 중복 누적 방지).
       - name: Comment artifact URL on PR (failure)
         if: failure() && github.event_name == 'pull_request'
-        uses: actions/github-script@v9
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         with:
           script: |
             const marker = '<!-- screenshot-fail-bot -->';
diff --git a/.github/workflows/unit-test.yml b/.github/workflows/unit-test.yml
index 835eebdaa3..4ffbd7f573 100644
--- a/.github/workflows/unit-test.yml
+++ b/.github/workflows/unit-test.yml
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Fetch pull request history for changed-module coverage
         env:
@@ -42,7 +42,7 @@ jobs:
         run: node --test .github/scripts/*.test.mjs
 
       - name: Set up JDK 21
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@b6effb05e454b25005698d916606bdc6ffcbf961 # v5.7.0
         with:
           distribution: 'temurin'
           java-version: '21'
@@ -62,7 +62,7 @@ jobs:
 
       - name: Upload Kover coverage reports
         id: kover-artifact
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: kover-jvm-coverage
           path: build/reports/kover/
@@ -79,7 +79,7 @@ jobs:
       # 실패한 테스트의 HTML/XML 리포트를 PR artifact 로 보존 — CI 로그에서 stack trace 추적이 빠름.
       - name: Upload test reports on failure
         if: failure()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: unit-test-reports
           path: |