chore(main): release 6.2.1 (#1849 )

chore: Update dist
fix: enforce allowed-account-ids on all auth paths (#1847 )
2026-08-24 04:25:05 +09:00 · 2026-06-26 14:23:45 -07:00 · 2026-06-26 20:42:54 +00:00 · 2026-06-26 13:33:19 -07:00 · 2026-06-23 04:00:00 +00:00 · 2026-06-23 03:56:47 +00:00
47 changed files with 104854 additions and 116669 deletions
@@ -0,0 +1,6 @@
+{
+  "inputs": ["./package.json"],
+  "output": "./THIRD-PARTY",
+  "overwrite": true,
+  "ci": true
+}
@@ -1,9 +1,11 @@
-*Issue #, if available:*
+_Issue #, if available:_

-*Description of changes:*
+_Description of changes:_

 ---

-* [ ] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws-actions/configure-aws-credentials/blob/main/CONTRIBUTING.md)
+- [ ] Have you followed the guidelines in our
+      [Contributing guide?](https://github.com/aws-actions/configure-aws-credentials/blob/main/CONTRIBUTING.md)

-By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.
+By submitting this pull request, I confirm that you can use, modify, copy, and
+redistribute this contribution, under the terms of your choice.
@@ -0,0 +1,5 @@
+name: "CodeQL config"
+
+paths-ignore:
+  - dist
+  - node_modules
@@ -0,0 +1,6 @@
+Port 9999
+Listen 127.0.0.1
+Timeout 600
+Allow 127.0.0.1
+LogFile "/home/runner/work/configure-aws-credentials/configure-aws-credentials/integ_proxy_log.txt"
+LogLevel Connect
@@ -13,7 +13,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Configure AWS credentials
-        uses: aws-actions/configure-aws-credentials@v4
+        uses: aws-actions/configure-aws-credentials@v6
        with:
          aws-region: us-west-2
          role-to-assume: ${{ secrets.SECRETS_AWS_PACKAGING_ROLE_TO_ASSUME }}
@@ -15,10 +15,10 @@ jobs:
      - name: Get Metadata
        id: dependabot-metadata
        uses: dependabot/fetch-metadata@v2
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
        name: Clone repo
      - name: Configure AWS credentials
-        uses: aws-actions/configure-aws-credentials@v4
+        uses: aws-actions/configure-aws-credentials@v6
        with:
          aws-region: us-west-2
          role-to-assume: ${{ secrets.CONFIGUREAWSCREDENTIALSPACKAGEROLEARN }}
@@ -17,7 +17,7 @@ jobs:
      contents: read
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
        with:
          fetch-depth: 0
          ref: ${{ github.ref_name }}
@@ -28,7 +28,7 @@ jobs:
          npm test
          npm run package
      - name: Configure AWS credentials
-        uses: aws-actions/configure-aws-credentials@v4
+        uses: aws-actions/configure-aws-credentials@v6
        with:
          aws-region: us-west-2
          role-to-assume: ${{ secrets.SECRETS_AWS_PACKAGING_ROLE_TO_ASSUME }}
@@ -47,5 +47,6 @@ jobs:
          git config user.email "github-aws-sdk-osds-automation@amazon.com"
          git remote set-url origin https://${{ env.OSDS_ACCESS_TOKEN }}@github.com/aws-actions/configure-aws-credentials.git
          git add dist
+          git add THIRD-PARTY
          git commit -m "chore: Update dist" || echo "No changes to commit"
          git push --force origin
@@ -4,6 +4,7 @@
    push:
      branches:
        - main
+    workflow_dispatch:

  permissions:
    id-token: write
@@ -15,12 +16,12 @@
      runs-on: ubuntu-latest
      steps:
        - name: Checkout Repository
-          uses: actions/checkout@v4
+          uses: actions/checkout@v5
          with:
            fetch-depth: 0

        - name: Configure AWS Credentials
-          uses: aws-actions/configure-aws-credentials@v4
+          uses: aws-actions/configure-aws-credentials@v6
          with:
            aws-region: us-west-2
            role-to-assume: ${{ secrets.SECRETS_AWS_PACKAGING_ROLE_TO_ASSUME }}
@@ -35,9 +36,41 @@
              ${{ secrets.OSDS_PACKAGING_ROLE }}

        - name: Run release-please
+          id: release
          uses: googleapis/release-please-action@v4
          with:
            release-type: node
            token: ${{ env.OSDS_ACCESS_TOKEN }}
            config-file: release-please-config.json
            manifest-file: .release-please-manifest.json
+
+        - name: Checkout Again
+          uses: actions/checkout@v5
+          with:
+            fetch-depth: 0
+
+        - name: Tag Major Version
+          if: ${{ steps.release.outputs.release_created }}
+          run: |
+            git config user.name "GitHub Actions"
+            git config user.email "github-aws-sdk-osds-automation@amazon.com"
+            if git rev-parse "v${{ steps.release.outputs.major }}" >/dev/null 2>&1; then
+              git tag -d "v${{ steps.release.outputs.major }}"
+              git push origin ":v${{ steps.release.outputs.major }}"
+            fi
+            git tag -a "v${{ steps.release.outputs.major }}" -m "Release v${{ steps.release.outputs.major }}"
+            git push origin "v${{ steps.release.outputs.major }}"
+
+        - name: Update README version references
+          if: ${{ steps.release.outputs.release_created }}
+          run: |
+            sed -i 's|configure-aws-credentials@v[0-9]*\.[0-9]*\.[0-9]*|configure-aws-credentials@${{ steps.release.outputs.tag_name }}|g' README.md
+            if git diff --quiet README.md; then
+              echo "README already up to date"
+            else
+              echo "::add-mask::${{ env.OSDS_ACCESS_TOKEN }}"
+              git remote set-url origin https://${{ env.OSDS_ACCESS_TOKEN }}@github.com/aws-actions/configure-aws-credentials.git
+              git add README.md
+              git commit -m "docs: update README version references to ${{ steps.release.outputs.tag_name }}"
+              git push --force origin
+            fi
@@ -0,0 +1,32 @@
+name: Run post-release integration test
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - 'dist/**'  
+  workflow_dispatch:
+
+jobs:
+  package_and_test:
+    name: Package dist files
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+      - name: Integation tests
+        uses: ./
+        with:
+          aws-region: us-west-2
+          role-to-assume: ${{ secrets.CAWSC_integ_role }}
+          role-session-name: IntegTestCAWSC
+      - name: Get caller identity
+        run: |
+          aws sts get-caller-identity
@@ -0,0 +1,281 @@
+name: Run pre-release integ tests
+on: 
+    pull_request_target:
+    workflow_dispatch:
+permissions:
+    contents: read
+
+jobs:
+  oidc:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions: 
+        id-token: write
+    strategy: 
+        fail-fast: false
+        matrix:
+            os: [windows-latest, ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    name: OIDC login test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false
+      - name: Configure AWS credentials
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.OIDC_integ_role }}
+      - name: Get Caller Identity
+        run: |
+            aws sts get-caller-identity
+
+  #can cut this test out if it's not necessary
+  static_assumeRole:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions:
+        id-token: write
+    strategy: 
+        fail-fast: false
+        matrix:
+            os: [windows-latest, ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    defaults: 
+        run:
+            shell: bash
+    name: Static IAM creds test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false
+      - name: assume creator Role
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.STATIC_USER_CREATION_ROLE }}
+      - name: create and mask access key
+        id: create-key
+        run: | 
+            AK_OUTPUT=$(aws iam create-access-key --user-name integ-test-static-user-${{ runner.os }})
+            AK_ID=$(echo $AK_OUTPUT | jq -r '.AccessKey.AccessKeyId')
+            SECRET_AK=$(echo $AK_OUTPUT | jq -r '.AccessKey.SecretAccessKey')
+            echo "::add-mask::$AK_ID"
+            echo "::add-mask::$SECRET_AK"
+            echo "STATIC_ACCESS_KEY_ID=$AK_ID" >> $GITHUB_OUTPUT
+            echo "STATIC_SECRET_ACCESS_KEY=$SECRET_AK" >> $GITHUB_OUTPUT
+      - name: sleep so key can propagate
+        run: sleep 30
+      - name: assume role with static creds
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.STATIC_TEST_TARGET_ROLE }}
+            aws-access-key-id: ${{ steps.create-key.outputs.STATIC_ACCESS_KEY_ID }}
+            aws-secret-access-key: ${{ steps.create-key.outputs.STATIC_SECRET_ACCESS_KEY }}
+      - name: check account
+        run: aws sts get-caller-identity
+      - name: log back into creator role
+        if: success() || failure()
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.STATIC_USER_CREATION_ROLE }}
+      - name: delete access key
+        if: success() || failure()
+        run: |
+            aws iam delete-access-key --user-name integ-test-static-user-${{ runner.os }} --access-key-id ${{ steps.create-key.outputs.STATIC_ACCESS_KEY_ID }}
+
+  role_chaining:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions: 
+        id-token: write
+    strategy: 
+        fail-fast: false
+        matrix:
+            os: [windows-latest, ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    name: Existing Creds + Role Chaining test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false    
+      - name: Configure AWS credentials
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.ROLE_chaining_1 }}
+      - name: Get Caller Identity
+        run: |
+          aws sts get-caller-identity
+      - name: assume second role
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.ROLE_chaining_2 }}
+            role-chaining: true
+      - name: get caller identity
+        run: |
+          aws sts get-caller-identity
+
+  inline_policy:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions: 
+        id-token: write
+    strategy: 
+        fail-fast: false
+        matrix:
+            os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    name: Inline Policy Test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false  
+      - name: get creds w scoped down policy
+        uses: ./
+        with: 
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.INLINE_policy_role }}
+            inline-session-policy: '{"Version":"2012-10-17","Statement":[{"Sid":"Stmt1","Effect":"Allow","Action":"s3:ListAllMyBuckets","Resource":"*"}]}'
+    
+      #NOTE: This step should succeed. The role should have permission only to list all buckets.
+      - name: list buckets
+        run: aws s3 ls > /dev/null
+
+      #NOTE: This step should fail. we don't want the role to have permission to see the bucket contents.    
+      - name: try to list bucket contents
+        id: bucketContentsStep
+        continue-on-error: true
+        run: aws s3 ls s3://cawsc-integ-tests-bucket > /dev/null
+
+      #But the test fails if we could list the bucket contents.
+      - name: fail if we can list bucket contents
+        if: steps.bucketContentsStep.outcome == 'success'
+        run: exit 1
+
+  http-proxy:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions:
+        id-token: write
+    runs-on: ubuntu-latest
+    name: HTTP Proxy Test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false  
+      - name: install tinyproxy
+        run: |
+          sudo apt-get update
+          sudo apt-get -y install tinyproxy
+      - name: start tinyproxy
+        run: tinyproxy -c .github/integ_tests/tinyproxy.conf
+      - name: Configure AWS credentials
+        continue-on-error: true
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.OIDC_integ_role }}
+            http-proxy: http://127.0.0.1:9999
+            retry-max-attempts: 4
+      - name: checkout logs 
+        run: cat integ_proxy_log.txt
+      - name: check logs to see if successful call
+        run: grep -q "Request" integ_proxy_log.txt && echo "PROXY_CALL_LOGGED=1" >> $GITHUB_ENV || echo "PROXY_CALL_LOGGED=0" >> $GITHUB_ENV
+      - name: fail job if bad call 
+        if: ${{ env.PROXY_CALL_LOGGED != 1 }}
+        run: exit 1
+
+  token-file:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions:
+        id-token: write
+    strategy: 
+      fail-fast: false
+      matrix:
+        os: [windows-latest, ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    name: Token File Test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false
+      - name: fetch token and write to file
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const fs = require('fs');
+            async function getIDTokenAction() {
+              const id_token = await core.getIDToken("sts.amazonaws.com");
+              return id_token;
+            }
+            const idToken = await getIDTokenAction();
+            fs.writeFileSync(".github/integ_tests/integ_token.txt", idToken, (err) => {
+              if (err) throw err;
+            });
+      - name: get creds with that file
+        uses: ./
+        with:
+            aws-region: us-west-2
+            role-to-assume: ${{ secrets.OIDC_integ_role }}
+            web-identity-token-file: .github/integ_tests/integ_token.txt
+            retry-max-attempts: 4
+      - name: check creds
+        run: aws sts get-caller-identity
+
+  profile-oidc:
+    if: ${{ github.event_name == 'workflow_dispatch' || (github.event.pull_request.user.login == 'aws-sdk-osds' && github.repository == 'aws-actions/configure-aws-credentials') }}
+    permissions: 
+        id-token: write
+    strategy: 
+        fail-fast: false
+        matrix:
+            os: [windows-latest, ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    name: OIDC profile writing test
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+        with:
+            fetch-depth: 0
+            persist-credentials: false
+
+      - name: make profile 1
+        uses: ./
+        with: 
+          aws-region: us-east-1
+          role-to-assume: ${{ secrets.INTEG_PROFILE_ROLE_1 }}
+          aws-profile: TestProfile1
+
+      - name: make profile 2
+        uses: ./
+        with: 
+          aws-region: us-east-2
+          role-to-assume: ${{ secrets.INTEG_PROFILE_ROLE_2 }}
+          aws-profile: TestProfile2
+          
+      - name: check profile1 
+        run: aws sts get-caller-identity --profile TestProfile1
+      
+      - name: check profile2
+        run: aws sts get-caller-identity --profile TestProfile2
+
+      - name: Get Caller Identity
+        id: no-creds-sts-step
+        continue-on-error: true
+        run: |
+            aws sts get-caller-identity
+
+      - name: fail if we got caller id with env creds
+        if: steps.no-creds-sts-step.outcome == 'success'
+        run: exit 1
@@ -2,6 +2,8 @@ on:
  [pull_request]

 name: Run unit tests
+permissions:
+  contents: read

 jobs:
  unit-test:
@@ -14,13 +16,13 @@ jobs:
    timeout-minutes: 5
    steps:
      - name: "Checkout repository"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
      - name: "Setup node"
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6.4.0
        with:
-          node-version: 20
+          node-version: 24
      - name: "Install dependencies"
-        uses: bahmutov/npm-install@v1
+        run: npm ci
      - name: "Run tests"
        run: npm run test --if-present
  lint:
@@ -29,7 +31,7 @@ jobs:
    timeout-minutes: 5
    steps:
      - name: "Checkout repostiory"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
      - name: "Setup node"
        uses: actions/setup-node@v4
        with:
@@ -1,3 +1,4 @@
+.history
 node_modules
 coverage
 .DS_Store
@@ -0,0 +1,17 @@
+default: true
+MD007:
+  indent: 4
+heading-style:
+  style: atx
+ul-style:
+  style: dash
+line-length:
+  stern: true
+  tables: false
+  code_blocks: false
+no-inline-html:
+  allowed_elements:
+    - details
+    - summary
+code-block-style:
+  style: fenced
@@ -1,5 +1,5 @@
 {
  ".release-please-manifest.json": "4.0.2",
-  "package.json": "4.0.2",
-  ".": "4.3.1"
+  "package.json": "6.0.0",
+  ".": "6.2.1"
 }
@@ -2,6 +2,105 @@

 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.

+## [6.2.1](https://github.com/aws-actions/configure-aws-credentials/compare/v6.2.0...v6.2.1) (2026-06-26)
+
+
+### Bug Fixes
+
+* enforce allowed-account-ids on all auth paths ([#1847](https://github.com/aws-actions/configure-aws-credentials/issues/1847)) ([4d281fb](https://github.com/aws-actions/configure-aws-credentials/commit/4d281fbc56a82e63c3fc14f2cc22361f34c97493))
+
+## [6.2.0](https://github.com/aws-actions/configure-aws-credentials/compare/v6.1.3...v6.2.0) (2026-06-01)
+
+### Features
+
+* add additional session tags by default ([#1775](https://github.com/aws-actions/configure-aws-credentials/issues/1775)) ([e0ba768](https://github.com/aws-actions/configure-aws-credentials/commit/e0ba7685077379a14a82d01fefd511490344ebfc))
+* add more retry logic and better logging ([#1764](https://github.com/aws-actions/configure-aws-credentials/issues/1764)) ([540d0c1](https://github.com/aws-actions/configure-aws-credentials/commit/540d0c13aedb8d55501d220bd2f0b3cdedfe84e8))
+* add regex validation to role-session-name ([#1765](https://github.com/aws-actions/configure-aws-credentials/issues/1765)) ([e354499](https://github.com/aws-actions/configure-aws-credentials/commit/e35449909c6ede5083a48ba4b8bbfaaa1cf09ba1))
+* Allow custom session tags to be passed when assuming a role ([#1759](https://github.com/aws-actions/configure-aws-credentials/issues/1759)) ([61f50f6](https://github.com/aws-actions/configure-aws-credentials/commit/61f50f630f383628add73c1eab3f1935ba07da2b))
+* expose run id in STS client user-agent ([#1774](https://github.com/aws-actions/configure-aws-credentials/issues/1774)) ([29d1be3](https://github.com/aws-actions/configure-aws-credentials/commit/29d1be30273e7ef371d59fccf6ec54572c64ec89))
+* support custom STS endpoints ([#1762](https://github.com/aws-actions/configure-aws-credentials/issues/1762)) ([8d52d05](https://github.com/aws-actions/configure-aws-credentials/commit/8d52d05d7a4521fa52b39de50cb6114b12e5c332))
+
+### Bug Fixes
+
+* skip credential check on output-env-credentials: false ([#1778](https://github.com/aws-actions/configure-aws-credentials/issues/1778)) ([58e7c47](https://github.com/aws-actions/configure-aws-credentials/commit/58e7c47adf77846879008deadfeeef8a6969fe6c))
+* assumeRole failing from session tag size too large ([#1808](https://github.com/aws-actions/configure-aws-credentials/issues/1808)) ([d6f5dc3](https://github.com/aws-actions/configure-aws-credentials/commit/d6f5dc331b44474b19a52caaf85fa4d637b13c8e))
+
+## [6.1.3](https://github.com/aws-actions/configure-aws-credentials/compare/v6.1.2...v6.1.3) (2026-05-28)
+
+### Bug Fixes
+
+* fix: allow kubelet token symlink in [#1805](https://github.com/aws-actions/configure-aws-credentials/issues/1805)
+
+## [6.1.2](https://github.com/aws-actions/configure-aws-credentials/compare/v6.1.1...v6.1.2) (2026-05-26)
+
+### Bug Fixes
+
+* additional filesystem checks ([#1799](https://github.com/aws-actions/configure-aws-credentials/issues/1799)) ([c39f282](https://github.com/aws-actions/configure-aws-credentials/commit/c39f282697aca8a78c522ecf1f7da9899a31432c))
+
+## [6.1.1](https://github.com/aws-actions/configure-aws-credentials/compare/v6.1.0...v6.1.1) (2026-05-05)
+
+
+### Miscellaneous Chores
+
+* various dependency updates
+
+## [6.1.0](https://github.com/aws-actions/configure-aws-credentials/compare/v6.0.0...v6.1.0) (2026-04-06)
+
+
+### Features
+
+* add skip cleanup option ([#1716](https://github.com/aws-actions/configure-aws-credentials/issues/1716)) ([11b1c58](https://github.com/aws-actions/configure-aws-credentials/commit/11b1c58b24724e66aa52a847862a0c1b0c4b0c7b)), closes [#1545](https://github.com/aws-actions/configure-aws-credentials/issues/1545)
+* Support usage of AWS Profiles ([#1696](https://github.com/aws-actions/configure-aws-credentials/issues/1696)) ([a7f0c82](https://github.com/aws-actions/configure-aws-credentials/commit/a7f0c828ac76e0d049e34c920172c60f579f9eb3))
+
+## [6.0.0](https://github.com/aws-actions/configure-aws-credentials/compare/v5.1.1...v6.0.0) (2026-02-04)
+
+
+### ⚠ BREAKING CHANGES
+
+* Update action to use node24 ([#1632](https://github.com/aws-actions/configure-aws-credentials/pull/1632)) ([a7a2c11](https://github.com/aws-actions/configure-aws-credentials/commit/a7a2c1125c67f40a1e95768f4e4a7d8f019f87af))
+
+### Features
+
+* add support to define transitive tag keys ([#1316](https://github.com/aws-actions/configure-aws-credentials/pull/1316)) ([232435c](https://github.com/aws-actions/configure-aws-credentials/commit/232435c0c05e51137544f0203931b84893d13b74)) ([930ebd9](https://github.com/aws-actions/configure-aws-credentials/pull/1628/changes/930ebd9bcaed959c3ba9e21567e8abbc3cae72c0))
+
+### Bug Fixes
+
+* properly output `aws-account-id` and `authenticated-arn` when using role-chaining ([#1633](https://github.com/aws-actions/configure-aws-credentials/pull/1633)) ([7ceaf96](https://github.com/aws-actions/configure-aws-credentials/commit/7ceaf96edc86cc1713cef59eba79feeb23f59da1))
+
+## [5.1.1](https://github.com/aws-actions/configure-aws-credentials/compare/v5.1.0...v5.1.1) (2025-11-24)
+
+
+### Miscellaneous Chores
+
+* release 5.1.1 ([56d6a58](https://github.com/aws-actions/configure-aws-credentials/commit/56d6a583f00f6bad6d19d91d53a7bc3b8143d0e9))
+
+## [5.1.0](https://github.com/aws-actions/configure-aws-credentials/compare/v5.0.0...v5.1.0) (2025-10-06)
+
+
+### Features
+
+* Add global timeout support ([#1487](https://github.com/aws-actions/configure-aws-credentials/issues/1487)) ([1584b8b](https://github.com/aws-actions/configure-aws-credentials/commit/1584b8b0e2062557287c28fbe9b8920df434e866))
+* add no-proxy support ([#1482](https://github.com/aws-actions/configure-aws-credentials/issues/1482)) ([dde9b22](https://github.com/aws-actions/configure-aws-credentials/commit/dde9b22a8e889a0821997a21a2c5a38020ee8de3))
+* Improve debug logging in retry logic ([#1485](https://github.com/aws-actions/configure-aws-credentials/issues/1485)) ([97ef425](https://github.com/aws-actions/configure-aws-credentials/commit/97ef425d73aa532439f54f90d0e83101a186c5a6))
+
+
+### Bug Fixes
+
+* properly expose getProxyForUrl (introduced in [#1482](https://github.com/aws-actions/configure-aws-credentials/issues/1482)) ([#1486](https://github.com/aws-actions/configure-aws-credentials/issues/1486)) ([cea4298](https://github.com/aws-actions/configure-aws-credentials/commit/cea42985ac88b42678fbc84c18066a7f07f05176))
+
+## [5.0.0](https://github.com/aws-actions/configure-aws-credentials/compare/v4.3.1...v5.0.0) (2025-09-03)
+
+
+### ⚠ BREAKING CHANGES
+
+* Cleanup input handling. Changes invalid boolean input behavior (see #1445)
+
+### Features
+
+* add skip OIDC option ([#1458](https://github.com/aws-actions/configure-aws-credentials/issues/1458)) ([8c45f6b](https://github.com/aws-actions/configure-aws-credentials/commit/8c45f6b08196feb86cfdbe431541d5571d9ab2c2))
+* Cleanup input handling. Changes invalid boolean input behavior (see [#1445](https://github.com/aws-actions/configure-aws-credentials/issues/1445)) ([74b3e27](https://github.com/aws-actions/configure-aws-credentials/commit/74b3e27aa80db064b5bb8c04b22fc607e817acf7))
+* support account id allowlist ([#1456](https://github.com/aws-actions/configure-aws-credentials/issues/1456)) ([c4be498](https://github.com/aws-actions/configure-aws-credentials/commit/c4be498953fc1da2707a50ce4b761a53af3d02af))
+
 ## [4.3.1](https://github.com/aws-actions/configure-aws-credentials/compare/v4.3.0...v4.3.1) (2025-08-04)


@@ -1,4 +1,8 @@
-## Code of Conduct
-This project has adopted the [Amazon Open Source Code of Conduct](https://aws.github.io/code-of-conduct).
-For more information see the [Code of Conduct FAQ](https://aws.github.io/code-of-conduct-faq) or contact
-opensource-codeofconduct@amazon.com with any additional questions or comments.
+# Code of Conduct
+
+This project has adopted the
+[Amazon Open Source Code of Conduct](https://aws.github.io/code-of-conduct). For
+more information see the
+[Code of Conduct FAQ](https://aws.github.io/code-of-conduct-faq) or contact
+<opensource-codeofconduct@amazon.com> with any additional questions or
+comments.
@@ -1,61 +1,117 @@
 # Contributing Guidelines

-Thank you for your interest in contributing to our project. Whether it's a bug report, new feature, correction, or additional
-documentation, we greatly value feedback and contributions from our community.
-
-Please read through this document before submitting any issues or pull requests to ensure we have all the necessary
-information to effectively respond to your bug report or contribution.
+Thank you for your interest in contributing to our project. Whether it's a bug
+report, new feature, correction, or additional documentation, we greatly value
+feedback and contributions from our community.

+Please read through this document before submitting any issues or pull requests
+to ensure we have all the necessary information to effectively respond to your
+bug report or contribution.

 ## Reporting Bugs/Feature Requests

-We welcome you to use the GitHub issue tracker to report bugs or suggest features.
+We welcome you to use the GitHub issue tracker to report bugs or suggest
+features.

-When filing an issue, please check [existing open](https://github.com/aws-actions/configure-aws-credentials/issues), or [recently closed](https://github.com/aws-actions/configure-aws-credentials/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aclosed%20), issues to make sure somebody else hasn't already
-reported the issue. Please try to include as much information as you can. Details like these are incredibly useful:
+When filing an issue, please check [existing open][open-issues],
+or [recently closed][closed-issues], issues to make sure somebody
+else hasn't already reported the issue.

-* A reproducible test case or series of steps
-* The version of our code being used
-* Any modifications you've made relevant to the bug
-* Anything unusual about your environment or deployment
+[open-issues]: https://github.com/aws-actions/configure-aws-credentials/issues
+[closed-issues]: https://github.com/aws-actions/configure-aws-credentials/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aclosed%20

+Please try to include as much information as you can. Details like
+these are incredibly useful:
+
+- A reproducible test case or series of steps
+- The version of our code being used
+- Any modifications you've made relevant to the bug
+- Anything unusual about your environment or deployment

 ## Contributing via Pull Requests
-Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that:

-1. You are working against the latest source on the *main* branch.
-2. You check existing open, and recently merged, pull requests to make sure someone else hasn't addressed the problem already.
-3. You open an issue to discuss any significant work - we would hate for your time to be wasted.
+Contributions via pull requests are much appreciated. Before sending us a pull
+request, please ensure that:
+
+1. You are working against the latest source on the _main_ branch.
+2. You check existing open, and recently merged, pull requests to make sure
+   someone else hasn't addressed the problem already.
+3. You open an issue to discuss any significant work - we would hate for your
+   time to be wasted.

 To send us a pull request, please:

 1. Fork the repository.
-2. Modify the source; please focus on the specific change you are contributing. If you also reformat all the code, it will be hard for us to focus on your change.
+2. Modify the source; please focus on the specific change you are contributing.
+   If you also reformat all the code, it will be hard for us to focus on your
+   change.
 3. Ensure local tests pass.
 4. Commit to your fork using clear commit messages.
-5. Send us a pull request, answering any default questions in the pull request interface.
-6. Pay attention to any automated CI failures reported in the pull request, and stay involved in the conversation.
+5. Send us a pull request, answering any default questions in the pull request
+   interface.
+6. Pay attention to any automated CI failures reported in the pull request, and
+   stay involved in the conversation.

-GitHub provides additional document on [forking a repository](https://help.github.com/articles/fork-a-repo/) and
-[creating a pull request](https://help.github.com/articles/creating-a-pull-request/).
+GitHub provides additional document on
+[forking a repository](https://help.github.com/articles/fork-a-repo/) and
+[creating a pull request][create-pr].

+[create-pr]:
+  https://help.github.com/articles/creating-a-pull-request/

 ## Finding contributions to work on
-Looking at the existing issues is a great way to find something to contribute on. As our projects, by default, use the default GitHub issue labels (enhancement/bug/duplicate/help wanted/invalid/question/wontfix), looking at any ['help wanted'](https://github.com/aws-actions/configure-aws-credentials/labels/help%20wanted) issues is a great place to start.

+Looking at the existing issues is a great way to find something to contribute
+on. As our projects, by default, use the default GitHub issue labels
+(enhancement/bug/duplicate/help wanted/invalid/question/wontfix), looking at any
+['help wanted'](https://github.com/aws-actions/configure-aws-credentials/labels/help%20wanted)
+issues is a great place to start.

 ## Code of Conduct
-This project has adopted the [Amazon Open Source Code of Conduct](https://aws.github.io/code-of-conduct).
-For more information see the [Code of Conduct FAQ](https://aws.github.io/code-of-conduct-faq) or contact
-opensource-codeofconduct@amazon.com with any additional questions or comments.

+This project has adopted the
+[Amazon Open Source Code of Conduct](https://aws.github.io/code-of-conduct). For
+more information see the
+[Code of Conduct FAQ](https://aws.github.io/code-of-conduct-faq) or contact
+<opensource-codeofconduct@amazon.com> with any additional questions or
+comments.

 ## Security issue notifications
-If you discover a potential security issue in this project we ask that you notify AWS/Amazon Security via our [vulnerability reporting page](http://aws.amazon.com/security/vulnerability-reporting/). Please do **not** create a public github issue.

+If you discover a potential security issue in this project we ask that you
+notify AWS/Amazon Security via our
+[vulnerability reporting page][vuln-report].
+
+[vuln-report]:
+  http://aws.amazon.com/security/vulnerability-reporting/
+Please do **not** create a public github issue.
+
+## Automated Tools
+
+The use of AI tooling for assisted development work is accepted and encouraged
+in this repository, but due to the volume of submissions we ask that you observe
+the following rules:
+
+- All issue and pull request submissions to this repository that are sourced by
+  AI must first be reviewed by a human before submitting to the repository.
+  Items reviewed in this way must include a statement like "generated by AI
+  tools, and reviewed by [person]"
+- Please ensure that your submissions are actually improvements. While we are
+  grateful for any proposed fixes, even if they are very small, behavior that
+  looks like creating noisy PRs or artificially inflating submission counts
+  is not acceptable.
+- We may close issues or pull requests, or limit your ability to interact with
+  this repository, for behavior that in our estimation violates these rules or
+  any of the other rules in this repository's
+  [Code of Conduct](CODE_OF_CONDUCT.md).

 ## Licensing

-See the [LICENSE](https://github.com/aws-actions/configure-aws-credentials/blob/main/LICENSE) file for our project's licensing. We will ask you to confirm the licensing of your contribution.
+See the
+[LICENSE](https://github.com/aws-actions/configure-aws-credentials/blob/main/LICENSE)
+file for our project's licensing. We will ask you to confirm the licensing of
+your contribution.

-We may ask you to sign a [Contributor License Agreement (CLA)](http://en.wikipedia.org/wiki/Contributor_License_Agreement) for larger changes.
+We may ask you to sign a
+[Contributor License Agreement (CLA)](http://en.wikipedia.org/wiki/Contributor_License_Agreement)
+for larger changes.
@@ -1,10 +1,10 @@
-
 name: '"Configure AWS Credentials" Action for GitHub Actions'
 description: Configures AWS credentials for use in subsequent steps in a GitHub Action workflow
 runs:
-  using: node20
+  using: node24
  main: dist/index.js
  post: dist/cleanup/index.js
+  post-if: env.AWS_SKIP_CLEANUP_STEP != 'true'
 branding:
  color: orange
  icon: cloud
@@ -12,6 +12,12 @@ inputs:
  aws-region:
    description: AWS Region, e.g. us-east-2
    required: true
+  aws-profile:
+    description: Name of the AWS profile to configure. When provided, credentials are written to ~/.aws/credentials and ~/.aws/config files instead of env variables (unless output-env-credentials is manually set to true). Name cannot contain whitespace, square brackets, or slashes.
+    required: false
+  overwrite-aws-profile:
+    description: Overwrite the given AWS profile if it already exists. Requires aws-profile. When set to false or not set, an error will be thrown if the profile already exists.
+    required: false
  role-to-assume:
    description: The Amazon Resource Name (ARN) of the role to assume. Use the provided credentials to assume an IAM role and configure the Actions environment with the assumed role credentials rather than with the provided credentials.
    required: false
@@ -37,6 +43,9 @@ inputs:
  http-proxy:
    description: Proxy to use for the AWS SDK agent
    required: false
+  no-proxy:
+    description: Hosts to skip for the proxy configuration
+    required: false
  mask-aws-account-id:
    description: Whether to mask the AWS account ID for these credentials as a secret value. By default the account ID will not be masked
    required: false
@@ -52,6 +61,9 @@ inputs:
  role-skip-session-tagging:
    description: Skip session tagging during role assumption
    required: false
+  transitive-tag-keys:
+    description: Define a list of transitive tag keys to pass when assuming a role
+    required: false
  inline-session-policy:
    description: Define an inline session policy to use when assuming a role
    required: false
@@ -64,7 +76,6 @@ inputs:
  output-env-credentials:
    description: Whether to export credentials as environment variables. If you set this to false, you probably want to use output-credentials.
    required: false
-    default: true
  unset-current-credentials:
    description: Whether to unset the existing credentials in your runner. May be useful if you run this action multiple times in the same job
    required: false
@@ -78,7 +89,24 @@ inputs:
    description: Some environments do not support special characters in AWS_SECRET_ACCESS_KEY. This option will retry fetching credentials until the secret access key does not contain special characters. This option overrides disable-retry and retry-max-attempts. This option is disabled by default
    required: false
  use-existing-credentials:
+    required: false
    description: When enabled, this option will check if there are already valid credentials in the environment. If there are, new credentials will not be fetched. If there are not, the action will run as normal.
+  allowed-account-ids:
+    required: false
+    description: An option comma-delimited list of expected AWS account IDs. The action will fail if we receive credentials for the wrong account.
+  force-skip-oidc:
+    required: false
+    description: When enabled, this option will skip using GitHub OIDC provider even if the id-token permission is set. This is sometimes useful when using IAM instance credentials.
+  action-timeout-s:
+    required: false
+    description: A global timeout in seconds for the action. When the timeout is reached, the action immediately exits. The default is to run without a timeout.
+  custom-tags:
+    description: Additional tags to apply to the assumed role session. Must be a JSON object provided as a string.
+    required: false
+  sts-endpoint:
+    description: Custom STS endpoint URL. Use this to point to an STS-compatible API (e.g. MinIO, LocalStack) instead of the default AWS STS endpoint for the region.
+    required: false
+
 outputs:
  aws-account-id:
    description: The AWS account ID for the provided credentials
@@ -12,6 +12,10 @@
      "performance": {
        "noDelete": "off"
      },
+      "correctness": {
+        // Specifying a radix disables interpretation of 0x as a number (needed for backwards compat)
+        "useParseIntRadix": "off"
+      },
      "complexity": {
        "noExtraBooleanCast": "off"
      }
@@ -2,8 +2,13 @@

 ## [federated-setup](./federated-setup/README.md)

-The directory contains templates for setting up the `configure-aws-credentials` federation between your GitHub Organization/repository and your AWS account.
+The directory contains templates for setting up the `configure-aws-credentials`
+federation between your GitHub Organization/repository and your AWS account.

 ## [cfn-deploy-example](./cfn-deploy-example/README.md)

-Repository example uses aws-action `configure-aws-credentials` with OIDC federation template [github-actions-oidc-federation-and-role](./github-actions-oidc-federation-and-role.yml). Example demonstrates a repository that deploys AWS CloudFormation template using cfn-deploy GitHub Action.
+Repository example uses aws-action `configure-aws-credentials` with OIDC
+federation template
+[github-actions-oidc-federation-and-role](./github-actions-oidc-federation-and-role.yml).
+Example demonstrates a repository that deploys AWS CloudFormation template using
+cfn-deploy GitHub Action.
@@ -6,7 +6,7 @@ jobs:
  sast-guard:
    runs-on: ubuntu-latest
    steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
    - uses: grolston/guard-action@main
      with:
        data_directory: './cloudformation/' ## change to your template directory
@@ -18,9 +18,9 @@ jobs:
      contents: read
    steps:
    - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
    - name: Configure AWS Credentials
-      uses: aws-actions/configure-aws-credentials@v4
+      uses: aws-actions/configure-aws-credentials@v6
      with:
        aws-region: us-east-1
        ## the following creates an ARN based on the values entered into github secrets
@@ -1,14 +1,24 @@
 # cfn-deploy example

-Example uses aws-action `configure-aws-credentials` with OIDC federation. Prior to using this example project, the user needs to deploy the [github-actions-oidc-federation-and-role](../federated-setup/github-actions-oidc-federation-and-role.yml) template in the AWS account they want to deploy the CloudFormation template into. Specify the GitHub Organization name, repository name, and the specific branch you want to deploy on.
+Example uses aws-action `configure-aws-credentials` with OIDC federation. Prior
+to using this example project, the user needs to deploy the
+[github-actions-oidc-federation-and-role](../federated-setup/github-actions-oidc-federation-and-role.yml)
+template in the AWS account they want to deploy the CloudFormation template
+into. Specify the GitHub Organization name, repository name, and the specific
+branch you want to deploy on.

-Within the [github/workflows](./.github/workflows/) directory there is a [compliance.yml](./.github/workflows/compliance.yml) and a [deploy.yml](./.github/workflows/deploy.yml). The deploy.yml file leverages the aws-action `configure-aws-credentials` and accesses GitHub Action Secrets for some of the variables. The compliance.yml runs static application security testing using cfn-guard.
+Within the [github/workflows](./.github/workflows/) directory there is a
+[compliance.yml](./.github/workflows/compliance.yml) and a
+[deploy.yml](./.github/workflows/deploy.yml). The deploy.yml file leverages the
+aws-action `configure-aws-credentials` and accesses GitHub Action Secrets for
+some of the variables. The compliance.yml runs static application security
+testing using cfn-guard.

 To use the example you will need to set the following GitHub Action Secrets:

-| Secret Key | Used With | Description |
-| --------- | -------- | -----------|
-| AWS_ACCOUNT_ID | configure-aws-credentials | The AWS account ID |
-| AWS_DEPLOY_ROLE | configure-aws-credentials | The name of the IAM role |
-| VPC_ID | aws-cloudformation-github-deploy | VPC ID the EC2 Bastion is deployed to |
-| SUBNET_ID | aws-cloudformation-github-deploy | Subnet ID the EC2 Bastion is deployed to |
+| Secret Key      | Used With                        | Description                              |
+| --------------- | -------------------------------- | ---------------------------------------- |
+| AWS_ACCOUNT_ID  | configure-aws-credentials        | The AWS account ID                       |
+| AWS_DEPLOY_ROLE | configure-aws-credentials        | The name of the IAM role                 |
+| VPC_ID          | aws-cloudformation-github-deploy | VPC ID the EC2 Bastion is deployed to    |
+| SUBNET_ID       | aws-cloudformation-github-deploy | Subnet ID the EC2 Bastion is deployed to |
@@ -2,8 +2,10 @@

 ## [github-action-oidc-federation](./github-actions-oidc-federation.yml)

-Setup of the OIDC federation between your GitHub Organization/repository and your AWS account.
+Setup of the OIDC federation between your GitHub Organization/repository and
+your AWS account.

 ## [github-actions-oidc-federation-and-role](./github-actions-oidc-federation-and-role.yml)

-Setup of the OIDC federation between your GitHub Organization/repository and your AWS account along with a role that only executes on specific branch.
+Setup of the OIDC federation between your GitHub Organization/repository and
+your AWS account along with a role that only executes on specific branch.
@@ -1,31 +0,0 @@
-/** @type {import('jest').Config} */
-const config = {
-  verbose: true,
-  transform: {
-    '^.+\\.m?[tj]sx?$': ['ts-jest'],
-  },
-  testMatch: [
-    '<rootDir>/src/**/__tests__/**/*.ts?(x)',
-    '<rootDir>/(test|src)/**/*(*.)@(spec|test).ts?(x)',
-    '<rootDir>/test/**/*.(test|spec).(js|jsx|ts|tsx)',
-  ],
-  clearMocks: true,
-  collectCoverage: true,
-  coverageReporters: ['json', 'lcov', 'clover', 'cobertura', 'text'],
-  coverageDirectory: 'coverage',
-  coveragePathIgnorePatterns: ['/node_modules/'],
-  testPathIgnorePatterns: ['/node_modules/'],
-  watchPathIgnorePatterns: ['/node_modules/'],
-  reporters: [
-    'default',
-    [
-      'jest-junit',
-      {
-        outputDirectory: 'test-reports',
-      },
-    ],
-  ],
-  preset: 'ts-jest/presets/default-legacy',
-};
-
-module.exports = config;
@@ -1,14 +1,15 @@
 {
  "name": "configure-aws-credentials",
  "description": "A GitHub Action to configure AWS credentials",
-  "version": "4.3.1",
+  "version": "6.2.1",
  "scripts": {
    "build": "tsc",
-    "lint": "biome check --error-on-warnings ./src",
-    "lint:fix": "biome check --write ./src",
-    "package": "npm run build && ncc build --license THIRD-PARTY -o dist && ncc build src/cleanup/index.ts -o dist/cleanup && cpy dist/THIRD-PARTY . && del-cli dist/THIRD-PARTY",
+    "lint": "biome check --error-on-warnings ./src ./test && markdownlint -i node_modules -i CHANGELOG.md '**/*.md'",
+    "lint:fix": "biome check --write ./src ./test && markdownlint -i node_modules -i CHANGELOG.md -f '**/*.md'",
+    "package": "esbuild src/index.ts --bundle --platform=node --target=node24 --outfile=dist/index.js && esbuild src/cleanup/index.ts --bundle --platform=node --target=node24 --outfile=dist/cleanup/index.js && npm run license",
    "test": "npm run lint && vitest run && npm run build",
-    "clean": "del-cli coverage test-reports node_modules"
+    "clean": "del-cli coverage test-reports node_modules",
+    "license": "generate-license-file --config ./.generatelicensefile.json"
  },
  "author": {
    "name": "Amazon.com, Inc. or its affiliates",
@@ -16,26 +17,26 @@
    "organization": true
  },
  "devDependencies": {
-    "@aws-sdk/credential-provider-env": "^3.858.0",
-    "@biomejs/biome": "2.1.3",
-    "@smithy/property-provider": "^4.0.3",
-    "@types/node": "^24.1.0",
-    "@vercel/ncc": "^0.38.3",
-    "@vitest/coverage-v8": "^3.2.4",
+    "@aws-sdk/credential-provider-env": "^3.972.49",
+    "@biomejs/biome": "2.5.0",
+    "@smithy/property-provider": "^4.4.2",
+    "@types/node": "^26.0.0",
+    "@vitest/coverage-v8": "4.1.9",
    "aws-sdk-client-mock": "^4.1.0",
-    "cpy-cli": "^5.0.0",
-    "del-cli": "^6.0.0",
+    "esbuild": "^0.28.1",
+    "generate-license-file": "^4.2.1",
    "json-schema": "^0.4.0",
-    "memfs": "^4.25.1",
+    "markdownlint-cli": "^0.49.0",
+    "memfs": "^4.57.8",
    "standard-version": "^9.5.0",
-    "typescript": "^5.8.3",
-    "vitest": "^3.2.4"
+    "typescript": "^6.0.3",
+    "vitest": "4.1.9"
  },
  "dependencies": {
-    "@actions/core": "^1.11.1",
-    "@aws-sdk/client-sts": "^3.858.0",
-    "@smithy/node-http-handler": "^4.1.0",
-    "https-proxy-agent": "^7.0.6"
+    "@actions/core": "^3.0.1",
+    "@aws-sdk/client-sts": "^3.1075.0",
+    "@smithy/node-http-handler": "^4.8.2",
+    "proxy-agent": "^8.0.2"
  },
  "keywords": [
    "aws",
@@ -43,7 +44,7 @@
    "github-action"
  ],
  "engines": {
-    "node": ">= 14.0.0"
+    "node": ">= 16.3.0"
  },
  "main": "build/index.js",
  "license": "MIT",
@@ -6,7 +6,8 @@
      "bump-minor-pre-major": false,
      "bump-patch-for-minor-pre-major": false,
      "draft": false,
-      "prerelease": false
+      "prerelease": false,
+      "exclude-paths": [".github", "dist"]
    }
  },
  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json"
@@ -2,70 +2,112 @@ import { info } from '@actions/core';
 import { STSClient } from '@aws-sdk/client-sts';
 import type { AwsCredentialIdentity } from '@aws-sdk/types';
 import { NodeHttpHandler } from '@smithy/node-http-handler';
-import { HttpsProxyAgent } from 'https-proxy-agent';
-import { errorMessage } from './helpers';
+import { ProxyAgent } from 'proxy-agent';
+import { buildCustomUserAgent, errorMessage, getCallerIdentity } from './helpers';
+import { ProxyResolver } from './ProxyResolver';

-const USER_AGENT = 'configure-aws-credentials-for-github-actions';
+if (!process.env.AWS_EXECUTION_ENV) {
+  process.env.AWS_EXECUTION_ENV = 'GitHubActions';
+}

 export interface CredentialsClientProps {
  region?: string;
  proxyServer?: string;
+  noProxy?: string;
+  stsEndpoint?: string;
+  roleChaining: boolean;
 }

 export class CredentialsClient {
  public region?: string;
  private _stsClient?: STSClient;
  private readonly requestHandler?: NodeHttpHandler;
+  private readonly stsEndpoint?: string;
+  private roleChaining?: boolean;

  constructor(props: CredentialsClientProps) {
-    this.region = props.region;
+    if (props.region !== undefined) {
+      this.region = props.region;
+    }
    if (props.proxyServer) {
      info('Configuring proxy handler for STS client');
-      const handler = new HttpsProxyAgent(props.proxyServer);
+      const proxyOptions: { httpProxy: string; httpsProxy: string; noProxy?: string } = {
+        httpProxy: props.proxyServer,
+        httpsProxy: props.proxyServer,
+      };
+      if (props.noProxy !== undefined) {
+        proxyOptions.noProxy = props.noProxy;
+      }
+      const getProxyForUrl = new ProxyResolver(proxyOptions).getProxyForUrl;
+      const handler = new ProxyAgent({ getProxyForUrl });
      this.requestHandler = new NodeHttpHandler({
-        httpAgent: handler,
        httpsAgent: handler,
+        httpAgent: handler,
      });
    }
+    if (props.stsEndpoint) {
+      this.stsEndpoint = props.stsEndpoint;
+    }
+    this.roleChaining = props.roleChaining;
  }

  public get stsClient(): STSClient {
-    if (!this._stsClient) {
-      this._stsClient = new STSClient({
-        region: this.region,
-        customUserAgent: USER_AGENT,
-        requestHandler: this.requestHandler ? this.requestHandler : undefined,
-      });
+    if (!this._stsClient || this.roleChaining) {
+      this._stsClient = this.createStsClient();
    }
    return this._stsClient;
  }

-  public async validateCredentials(expectedAccessKeyId?: string, roleChaining?: boolean) {
-    let credentials: AwsCredentialIdentity;
-    try {
-      credentials = await this.loadCredentials();
-      if (!credentials.accessKeyId) {
-        throw new Error('Access key ID empty after loading credentials');
+  // Builds an STS client using the action's configured region/endpoint/proxy. When explicit credentials are provided,
+  // the client uses them directly instead of the SDK default credential provider chain.
+  // This matters for validateAccountId.
+  private createStsClient(credentials?: AwsCredentialIdentity): STSClient {
+    return new STSClient({
+      customUserAgent: buildCustomUserAgent(),
+      ...(this.region !== undefined && { region: this.region }),
+      ...(this.stsEndpoint !== undefined && { endpoint: this.stsEndpoint }),
+      ...(this.requestHandler !== undefined && { requestHandler: this.requestHandler }),
+      ...(credentials !== undefined && { credentials }),
+    });
+  }
+
+  // Validates that the credentials the action will hand to subsequent steps actually work, and returns the resolved
+  // caller identity (account + ARN). "Work" is proven by a sts:GetCallerIdentity call, which both confirms the
+  // credentials are accepted by AWS and returns the identity for later checks and outputs to use.
+  public async validateCredentials(
+    credentials?: AwsCredentialIdentity,
+    expectedAccessKeyId?: string,
+    roleChaining?: boolean,
+  ): Promise<Awaited<ReturnType<typeof getCallerIdentity>>> {
+    if (!credentials) {
+      let resolved: AwsCredentialIdentity;
+      try {
+        resolved = await this.loadCredentials();
+        if (!resolved.accessKeyId) {
+          throw new Error('Access key ID empty after loading credentials');
+        }
+      } catch (error) {
+        throw new Error(`Credentials could not be loaded, please check your action inputs: ${errorMessage(error)}`);
      }
-    } catch (error) {
-      throw new Error(`Credentials could not be loaded, please check your action inputs: ${errorMessage(error)}`);
-    }
-
-    if (!roleChaining) {
-      const actualAccessKeyId = credentials.accessKeyId;
-
-      if (expectedAccessKeyId && expectedAccessKeyId !== actualAccessKeyId) {
+      if (!roleChaining && expectedAccessKeyId && expectedAccessKeyId !== resolved.accessKeyId) {
        throw new Error(
-          'Unexpected failure: Credentials loaded by the SDK do not match the access key ID configured by the action',
+          'Credentials loaded by the SDK do not match the expected access key ID configured by the action',
        );
      }
    }
+
+    const client = credentials ? this.createStsClient(credentials) : this.stsClient;
+    try {
+      return await getCallerIdentity(client);
+    } catch (error) {
+      throw new Error(`Credentials could not be loaded, please check your action inputs: ${errorMessage(error)}`);
+    }
  }

  private async loadCredentials() {
-    const client = new STSClient({
-      requestHandler: this.requestHandler ? this.requestHandler : undefined,
-    });
+    const config = {} as { requestHandler?: NodeHttpHandler };
+    if (this.requestHandler !== undefined) config.requestHandler = this.requestHandler;
+    const client = new STSClient(config);
    return client.config.credentials();
  }
 }
@@ -0,0 +1,71 @@
+// Based on https://github.com/Rob--W/proxy-from-env/tree/caf8c32301afdac8b5feaf346028bd8240690144
+// See https://github.com/Rob--W/proxy-from-env/blob/caf8c32301afdac8b5feaf346028bd8240690144/LICENSE
+import type * as http from 'node:http';
+
+const DEFAULT_PORTS: Record<string, number> = {
+  http: 80,
+  https: 443,
+};
+export interface ProxyOptions {
+  readonly noProxy?: string;
+  readonly httpsProxy?: string;
+  readonly httpProxy?: string;
+}
+
+export class ProxyResolver {
+  options: ProxyOptions;
+  constructor(options: ProxyOptions) {
+    this.options = options;
+  }
+
+  // This method matches the interface expected by 'proxy-agent'. It is an arrow function to bind 'this'.
+  public readonly getProxyForUrl = (url: string, _req: http.ClientRequest): string => {
+    return this.getProxyForUrlOptions(url, this.options);
+  };
+
+  private getProxyForUrlOptions(url: string | URL, options?: ProxyOptions): string {
+    let parsedUrl: URL;
+    try {
+      parsedUrl = typeof url === 'string' ? new URL(url) : url;
+    } catch (_) {
+      return ''; // Don't proxy invalid URLs.
+    }
+    const proto = parsedUrl.protocol.split(':', 1)[0];
+    if (!proto) return ''; // Don't proxy URLs without a protocol.
+    const hostname = parsedUrl.host;
+    const port = parseInt(parsedUrl.port || '') || DEFAULT_PORTS[proto] || 0;
+
+    if (options?.noProxy && !this.shouldProxy(hostname, port, options.noProxy)) return '';
+    if (proto === 'http' && options?.httpProxy) return options.httpProxy;
+    if (proto === 'https' && options?.httpsProxy) return options.httpsProxy;
+    return ''; // No proxy configured for this protocol or unknown protocol
+  }
+
+  private shouldProxy(hostname: string, port: number, noProxy: string): boolean {
+    if (!noProxy) return true;
+    if (noProxy === '*') return false; // Never proxy if wildcard is set.
+
+    return noProxy.split(/[,\s]/).every((proxy) => {
+      if (!proxy) return true; // Skip zero-length hosts.
+
+      const parsedProxy = proxy.match(/^(.+):(\d+)$/);
+      const parsedProxyHostname = parsedProxy ? parsedProxy[1] : proxy;
+      const parsedProxyPort = parsedProxy?.[2] ? parseInt(parsedProxy[2]) : 0;
+
+      if (parsedProxyPort && parsedProxyPort !== port) return true; // Skip if ports don't match.
+
+      if (parsedProxyHostname && !/^[.*]/.test(parsedProxyHostname)) {
+        // No wildcards, so stop proxying if there is an exact match.
+        return hostname !== parsedProxyHostname;
+      }
+
+      let cleanProxyHostname = parsedProxyHostname;
+      if (parsedProxyHostname && parsedProxyHostname.charAt(0) === '*') {
+        // Remove leading wildcard.
+        cleanProxyHostname = parsedProxyHostname.slice(1);
+      }
+      // Stop proxying if the hostname ends with the no_proxy host.
+      return !cleanProxyHostname || !hostname.endsWith(cleanProxyHostname);
+    });
+  }
+}
@@ -1,14 +1,18 @@
 import assert from 'node:assert';
-import fs from 'node:fs';
 import path from 'node:path';
 import * as core from '@actions/core';
 import type { AssumeRoleCommandInput, STSClient, Tag } from '@aws-sdk/client-sts';
-import { AssumeRoleCommand, AssumeRoleWithWebIdentityCommand } from '@aws-sdk/client-sts';
+import {
+  AssumeRoleCommand,
+  AssumeRoleWithWebIdentityCommand,
+  PackedPolicyTooLargeException,
+} from '@aws-sdk/client-sts';
 import type { CredentialsClient } from './CredentialsClient';
-import { errorMessage, isDefined, sanitizeGitHubVariables } from './helpers';
+import { errorMessage, isDefined, readFileUtf8, sanitizeGitHubVariables } from './helpers';

 async function assumeRoleWithOIDC(params: AssumeRoleCommandInput, client: STSClient, webIdentityToken: string) {
  delete params.Tags;
+  delete params.TransitiveTagKeys;
  core.info('Assuming role with OIDC');
  try {
    const creds = await client.send(
@@ -35,13 +39,14 @@ async function assumeRoleWithWebIdentityTokenFile(
  const webIdentityTokenFilePath = path.isAbsolute(webIdentityTokenFile)
    ? webIdentityTokenFile
    : path.join(workspace, webIdentityTokenFile);
-  if (!fs.existsSync(webIdentityTokenFilePath)) {
+  const webIdentityToken = readFileUtf8(webIdentityTokenFilePath);
+  if (webIdentityToken === null) {
    throw new Error(`Web identity token file does not exist: ${webIdentityTokenFilePath}`);
  }
  core.info('Assuming role with web identity token file');
  try {
-    const webIdentityToken = fs.readFileSync(webIdentityTokenFilePath, 'utf8');
    delete params.Tags;
+    delete params.TransitiveTagKeys;
    const creds = await client.send(
      new AssumeRoleWithWebIdentityCommand({
        ...params,
@@ -60,6 +65,13 @@ async function assumeRoleWithCredentials(params: AssumeRoleCommandInput, client:
    const creds = await client.send(new AssumeRoleCommand({ ...params }));
    return creds;
  } catch (error) {
+    if (error instanceof PackedPolicyTooLargeException) {
+      core.info('Session tag size is too large; dropping droppable tags and retrying.');
+      const droppableKeys = new Set(DROPPABLE_TAG_SOURCES.map((s) => s.key));
+      params.Tags = params.Tags?.filter((tag) => !droppableKeys.has(tag.Key ?? ''));
+      const creds = await client.send(new AssumeRoleCommand({ ...params }));
+      return creds;
+    }
    throw new Error(`Could not assume role with user credentials: ${errorMessage(error)}`);
  }
 }
@@ -70,12 +82,106 @@ export interface assumeRoleParams {
  roleDuration: number;
  roleSessionName: string;
  roleSkipSessionTagging?: boolean;
+  transitiveTagKeys?: string[];
  sourceAccountId?: string;
  roleExternalId?: string;
  webIdentityTokenFile?: string;
  webIdentityToken?: string;
  inlineSessionPolicy?: string;
  managedSessionPolicies?: { arn: string }[];
+  customTags?: string;
+}
+
+const TAG_KEY_REGEX = /^[\p{L}\p{Z}\p{N}_.:/=+\-@]+$/u;
+const TAG_VALUE_REGEX = /^[\p{L}\p{Z}\p{N}_.:/=+\-@]*$/u;
+const MAX_TAG_KEY_LENGTH = 128;
+const MAX_TAG_VALUE_LENGTH = 256;
+const MAX_SESSION_TAGS = 50;
+
+// Identity/audit primitives. Always emitted and cannot be dropped.
+const NON_DROPPABLE_TAG_SOURCES: ReadonlyArray<{ key: string; envVar: string }> = [
+  { key: 'Repository', envVar: 'GITHUB_REPOSITORY' },
+  { key: 'Workflow', envVar: 'GITHUB_WORKFLOW' },
+  { key: 'Action', envVar: 'GITHUB_ACTION' },
+  { key: 'Actor', envVar: 'GITHUB_ACTOR' },
+  { key: 'Commit', envVar: 'GITHUB_SHA' },
+  { key: 'Branch', envVar: 'GITHUB_REF' },
+];
+
+// Convenience metadata. If the AssumeRole call fails due to compressed size of
+// session tags being too large, we will drop these tags and retry once.
+const DROPPABLE_TAG_SOURCES: ReadonlyArray<{ key: string; envVar: string }> = [
+  { key: 'EventName', envVar: 'GITHUB_EVENT_NAME' },
+  { key: 'BaseRef', envVar: 'GITHUB_BASE_REF' },
+  { key: 'HeadRef', envVar: 'GITHUB_HEAD_REF' },
+  { key: 'RunId', envVar: 'GITHUB_RUN_ID' },
+  { key: 'Job', envVar: 'GITHUB_JOB' },
+  { key: 'TriggeringActor', envVar: 'GITHUB_TRIGGERING_ACTOR' },
+];
+
+const PROTECTED_TAG_KEYS = new Set<string>([
+  'GitHub',
+  ...NON_DROPPABLE_TAG_SOURCES.map((s) => s.key),
+  ...DROPPABLE_TAG_SOURCES.map((s) => s.key),
+]);
+
+export function parseAndValidateCustomTags(customTags: string, existingTags: Tag[]): Tag[] {
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(customTags);
+  } catch {
+    throw new Error('custom-tags: input is not valid JSON');
+  }
+
+  if (typeof parsed !== 'object' || parsed === null || Array.isArray(parsed)) {
+    throw new Error('custom-tags: input must be a JSON object (not an array or primitive)');
+  }
+
+  const newTags: Tag[] = [];
+
+  for (const [key, value] of Object.entries(parsed)) {
+    if (typeof value === 'object') {
+      throw new Error(
+        `custom-tags: value for key '${key}' must be a string, number, or boolean (not an object or array)`,
+      );
+    }
+
+    const stringValue = String(value);
+
+    if (key.length === 0 || key.length > MAX_TAG_KEY_LENGTH) {
+      throw new Error(`custom-tags: key '${key}' must be between 1 and ${MAX_TAG_KEY_LENGTH} characters`);
+    }
+    if (stringValue.length > MAX_TAG_VALUE_LENGTH) {
+      throw new Error(
+        `custom-tags: value for key '${key}' exceeds maximum length of ${MAX_TAG_VALUE_LENGTH} characters`,
+      );
+    }
+    if (!TAG_KEY_REGEX.test(key)) {
+      throw new Error(
+        `custom-tags: key '${key}' contains invalid characters. Allowed: unicode letters, digits, spaces, and _.:/=+-@`,
+      );
+    }
+    if (stringValue.length > 0 && !TAG_VALUE_REGEX.test(stringValue)) {
+      throw new Error(
+        `custom-tags: value for key '${key}' contains invalid characters. Allowed: unicode letters, digits, spaces, and _.:/=+-@`,
+      );
+    }
+    if (PROTECTED_TAG_KEYS.has(key)) {
+      throw new Error(
+        `custom-tags: key '${key}' conflicts with a protected session tag set by this action and cannot be overridden`,
+      );
+    }
+
+    newTags.push({ Key: key, Value: stringValue });
+  }
+
+  if (existingTags.length + newTags.length > MAX_SESSION_TAGS) {
+    throw new Error(
+      `custom-tags: total session tags (${existingTags.length + newTags.length}) would exceed the AWS limit of ${MAX_SESSION_TAGS}`,
+    );
+  }
+
+  return newTags;
 }

 export async function assumeRole(params: assumeRoleParams) {
@@ -87,10 +193,12 @@ export async function assumeRole(params: assumeRoleParams) {
    roleDuration,
    roleSessionName,
    roleSkipSessionTagging,
+    transitiveTagKeys,
    webIdentityTokenFile,
    webIdentityToken,
    inlineSessionPolicy,
    managedSessionPolicies,
+    customTags,
  } = { ...params };

  // Load GitHub environment variables
@@ -99,28 +207,39 @@ export async function assumeRole(params: assumeRoleParams) {
    throw new Error('Missing required environment variables. Are you running in GitHub Actions?');
  }

-  // Load role session tags
-  const tagArray: Tag[] = [
-    { Key: 'GitHub', Value: 'Actions' },
-    { Key: 'Repository', Value: GITHUB_REPOSITORY },
-    { Key: 'Workflow', Value: sanitizeGitHubVariables(GITHUB_WORKFLOW) },
-    { Key: 'Action', Value: GITHUB_ACTION },
-    { Key: 'Actor', Value: sanitizeGitHubVariables(GITHUB_ACTOR) },
-    { Key: 'Commit', Value: GITHUB_SHA },
-  ];
-  if (process.env.GITHUB_REF) {
-    tagArray.push({
-      Key: 'Branch',
-      Value: sanitizeGitHubVariables(process.env.GITHUB_REF),
-    });
+  // Build session tags. Values are sanitized because the AWS tag value spec is more
+  // restrictive than permissible characters in environment variables.
+  const protectedTags: Tag[] = [{ Key: 'GitHub', Value: 'Actions' }];
+  for (const { key, envVar } of NON_DROPPABLE_TAG_SOURCES) {
+    const value = process.env[envVar];
+    if (value) {
+      protectedTags.push({ Key: key, Value: sanitizeGitHubVariables(value) });
+    }
  }
+  for (const { key, envVar } of DROPPABLE_TAG_SOURCES) {
+    const value = process.env[envVar];
+    if (value) {
+      protectedTags.push({ Key: key, Value: sanitizeGitHubVariables(value) });
+    }
+  }
+
+  const parsedCustomTags: Tag[] = customTags ? parseAndValidateCustomTags(customTags, protectedTags) : [];
+
+  const tagArray: Tag[] = [...protectedTags, ...parsedCustomTags];
+
  const tags = roleSkipSessionTagging ? undefined : tagArray;
  if (!tags) {
    core.debug('Role session tagging has been skipped.');
  } else {
-    core.debug(`${tags.length} role session tags are being used.`);
+    core.debug(`${tags.length} role session tags are being used:`);
+    core.debug(JSON.stringify(tagArray));
  }

+  //only populate transitiveTagKeys array if user is actually using session tagging
+  const transitiveTagKeysArray = roleSkipSessionTagging
+    ? undefined
+    : transitiveTagKeys?.filter((key) => tags?.some((tag) => tag.Key === key));
+
  // Calculate role ARN from name and account ID (currently only supports `aws` partition)
  let roleArn = roleToAssume;
  if (!roleArn.startsWith('arn:aws')) {
@@ -137,12 +256,17 @@ export async function assumeRole(params: assumeRoleParams) {
    RoleSessionName: roleSessionName,
    DurationSeconds: roleDuration,
    Tags: tags ? tags : undefined,
+    TransitiveTagKeys: transitiveTagKeysArray ? transitiveTagKeysArray : undefined,
    ExternalId: roleExternalId ? roleExternalId : undefined,
    Policy: inlineSessionPolicy ? inlineSessionPolicy : undefined,
    PolicyArns: managedSessionPolicies?.length ? managedSessionPolicies : undefined,
  };
  const keys = Object.keys(commonAssumeRoleParams) as Array<keyof typeof commonAssumeRoleParams>;
-  keys.forEach((k) => commonAssumeRoleParams[k] === undefined && delete commonAssumeRoleParams[k]);
+  keys.forEach((k) => {
+    if (commonAssumeRoleParams[k] === undefined) {
+      delete commonAssumeRoleParams[k];
+    }
+  });

  // Instantiate STS client
  const stsClient = credentialsClient.stsClient;
@@ -1,5 +1,5 @@
 import * as core from '@actions/core';
-import { errorMessage } from '../helpers';
+import { errorMessage, getBooleanInput } from '../helpers';

 /**
 * When the GitHub Actions job is done, clean up any environment variables that
@@ -13,8 +13,9 @@ import { errorMessage } from '../helpers';
 */

 export function cleanup() {
-  const outputEnvCredentialsInput = core.getInput('output-env-credentials', { required: false }) || 'true';
-  if (outputEnvCredentialsInput === 'true') {
+  // Only attempt to change environment variables if we changed them in the first place
+  const awsProfile = core.getInput('aws-profile', { required: false });
+  if (getBooleanInput('output-env-credentials', { required: false, default: !awsProfile })) {
    try {
      // The GitHub Actions toolkit does not have an option to completely unset
      // environment variables, so we overwrite the current value with an empty
@@ -25,11 +26,15 @@ export function cleanup() {
      core.exportVariable('AWS_SESSION_TOKEN', '');
      core.exportVariable('AWS_DEFAULT_REGION', '');
      core.exportVariable('AWS_REGION', '');
+      if (core.getInput('aws-profile')) {
+        core.exportVariable('AWS_PROFILE', '');
+      }
    } catch (error) {
      core.setFailed(errorMessage(error));
    }
  }
 }
+
 /* c8 ignore start */
 if (require.main === module) {
  try {
@@ -1,11 +1,35 @@
+import * as fs from 'node:fs';
+import * as path from 'node:path';
 import * as core from '@actions/core';
-import type { Credentials } from '@aws-sdk/client-sts';
+import type { Credentials, STSClient } from '@aws-sdk/client-sts';
 import { GetCallerIdentityCommand } from '@aws-sdk/client-sts';
+import type { AwsCredentialIdentity } from '@aws-sdk/types';
+import type { UserAgent } from '@smithy/types';
 import type { CredentialsClient } from './CredentialsClient';

 const MAX_TAG_VALUE_LENGTH = 256;
 const SANITIZATION_CHARACTER = '_';
 const SPECIAL_CHARS_REGEX = /[!@#$%^&*()_+\-=[\]{};':"\\|,.<>/?]+/;
+const USER_AGENT_PREFIX = 'configure-aws-credentials-for-github-actions';
+const UA_FIELDS: ReadonlyArray<{ env: string; label: string; pattern: RegExp }> = [
+  { env: 'GITHUB_ACTION', label: 'action', pattern: /^[A-Za-z0-9_-]{1,128}$/ },
+  { env: 'GITHUB_RUN_ID', label: 'run_id', pattern: /^[0-9]{1,20}$/ },
+  { env: 'GITHUB_RUN_ATTEMPT', label: 'attempt', pattern: /^[0-9]{1,10}$/ },
+];
+
+export function buildCustomUserAgent(): UserAgent {
+  const tokens: UserAgent = [[USER_AGENT_PREFIX]];
+  for (const { env, label, pattern } of UA_FIELDS) {
+    const value = process.env[env];
+    if (value === undefined) continue;
+    if (pattern.test(value)) {
+      tokens.push(['md', `${label}#${value}`]);
+    } else {
+      core.warning(`${env} has unexpected format; omitting from User-Agent`);
+    }
+  }
+  return tokens;
+}

 export function translateEnvVariables() {
  const envVars = [
@@ -20,6 +44,7 @@ export function translateEnvVariables() {
    'ROLE_EXTERNAL_ID',
    'ROLE_SESSION_NAME',
    'ROLE_SKIP_SESSION_TAGGING',
+    'TRANSITIVE_TAG_KEYS',
    'INLINE_SESSION_POLICY',
    'MANAGED_SESSION_POLICIES',
    'OUTPUT_CREDENTIALS',
@@ -28,6 +53,8 @@ export function translateEnvVariables() {
    'RETRY_MAX_ATTEMPTS',
    'SPECIAL_CHARACTERS_WORKAROUND',
    'USE_EXISTING_CREDENTIALS',
+    'NO_PROXY',
+    'OVERWRITE_AWS_PROFILE',
  ];
  // Treat HTTPS_PROXY as HTTP_PROXY. Precedence is HTTPS_PROXY > HTTP_PROXY
  if (process.env.HTTPS_PROXY) process.env.HTTP_PROXY = process.env.HTTPS_PROXY;
@@ -109,15 +136,25 @@ export function exportRegion(region: string, outputEnvCredentials?: boolean) {
  }
 }

-// Obtains account ID from STS Client and sets it as output
-export async function exportAccountId(credentialsClient: CredentialsClient, maskAccountId?: boolean) {
-  const client = credentialsClient.stsClient;
+export async function getCallerIdentity(client: STSClient): Promise<{ Account: string; Arn: string; UserId?: string }> {
  const identity = await client.send(new GetCallerIdentityCommand({}));
-  const accountId = identity.Account;
-  const arn = identity.Arn;
-  if (!accountId || !arn) {
+  if (!identity.Account || !identity.Arn) {
    throw new Error('Could not get Account ID or ARN from STS. Did you set credentials?');
  }
+  const result: { Account: string; Arn: string; UserId?: string } = {
+    Account: identity.Account,
+    Arn: identity.Arn,
+  };
+  if (identity.UserId !== undefined) {
+    result.UserId = identity.UserId;
+  }
+  return result;
+}
+
+// Emits the account ID and ARN of an already-resolved caller identity as action outputs.
+export function exportAccountId(identity: { Account: string; Arn: string }, maskAccountId?: boolean) {
+  const accountId = identity.Account;
+  const arn = identity.Arn;
  if (maskAccountId) {
    core.setSecret(accountId);
    core.setSecret(arn);
@@ -127,6 +164,35 @@ export async function exportAccountId(credentialsClient: CredentialsClient, mask
  return accountId;
 }

+// Validates that the account of the already-resolved caller identity is in the allow-list provided via the
+// `allowed-account-ids` input.
+export function validateAccountId(expectedAccountIds: string[] | undefined, account: string | undefined): void {
+  if (!expectedAccountIds || expectedAccountIds.length === 0 || expectedAccountIds[0] === '') {
+    return;
+  }
+  if (!account || !expectedAccountIds.includes(account)) {
+    throw new Error(
+      `The account ID of the provided credentials (${
+        account ?? 'unknown'
+      }) does not match any of the expected account IDs: ${expectedAccountIds.join(', ')}`,
+    );
+  }
+}
+
+// Converts the STS Credentials shape (returned by AssumeRole and provided as action inputs) into
+// the AwsCredentialIdentity shape the SDK expects when credentials are supplied explicitly to a
+// client. Returns undefined if the access key ID or secret access key is missing.
+export function toCredentialIdentity(creds?: Partial<Credentials>): AwsCredentialIdentity | undefined {
+  if (!creds?.AccessKeyId || !creds.SecretAccessKey) {
+    return undefined;
+  }
+  return {
+    accessKeyId: creds.AccessKeyId,
+    secretAccessKey: creds.SecretAccessKey,
+    ...(creds.SessionToken && { sessionToken: creds.SessionToken }),
+  };
+}
+
 // Tags have a more restrictive set of acceptable characters than GitHub environment variables can.
 // This replaces anything not conforming to the tag restrictions by inverting the regular expression.
 // See the AWS documentation for constraint specifics https://docs.aws.amazon.com/STS/latest/APIReference/API_Tag.html.
@@ -175,20 +241,33 @@ export async function retryAndBackoff<T>(
  maxRetries = 12,
  retries = 0,
  base = 50,
+  label?: string,
 ): Promise<T> {
  try {
    return await fn();
  } catch (err) {
    if (!isRetryable) {
+      core.debug(`retryAndBackoff: error is not retryable: ${errorMessage(err)}`);
      throw err;
    }
    // It's retryable, so sleep and retry.
-    await sleep(Math.random() * (2 ** retries * base));
-    retries += 1;
-    if (retries >= maxRetries) {
+    const delay = Math.random() * (2 ** retries * base);
+    const nextRetry = retries + 1;
+    const opName = label ? ` ${label}` : '';
+
+    core.info(
+      `Retry${opName}: attempt ${nextRetry} of ${maxRetries} failed: ${errorMessage(err)}. ` +
+        `Retrying after ${Math.floor(delay)}ms.`,
+    );
+
+    await sleep(delay);
+
+    if (nextRetry >= maxRetries) {
+      core.info(`Retry${opName}: reached max retries (${maxRetries}); giving up.`);
      throw err;
    }
-    return await retryAndBackoff(fn, isRetryable, maxRetries, retries, base);
+
+    return await retryAndBackoff(fn, isRetryable, maxRetries, nextRetry, base, label);
  }
 }

@@ -214,3 +293,135 @@ export async function areCredentialsValid(credentialsClient: CredentialsClient)
    return false;
  }
 }
+
+/**
+ * Like core.getBooleanInput, but respects the required option.
+ *
+ * From https://github.com/actions/toolkit/blob/6876e2a664ec02908178087905b9155e9892a437/packages/core/src/core.ts
+ *
+ * Gets the input value of the boolean type in the YAML 1.2 "core schema" specification.
+ * Support boolean input list: `true | True | TRUE | false | False | FALSE` .
+ * The return value is also in boolean type.
+ * ref: https://yaml.org/spec/1.2/spec.html#id2804923
+ *
+ * @param     name     name of the input to get
+ * @param     options  optional. See core.InputOptions. Also supports optional 'default' if the input is not set
+ * @returns   boolean
+ */
+export function getBooleanInput(name: string, options?: core.InputOptions & { default?: boolean }): boolean {
+  const trueValue = ['true', 'True', 'TRUE'];
+  const falseValue = ['false', 'False', 'FALSE'];
+  const optionsWithoutDefault = { ...options };
+  delete optionsWithoutDefault.default;
+  const val = core.getInput(name, optionsWithoutDefault);
+  if (trueValue.includes(val)) return true;
+  if (falseValue.includes(val)) return false;
+  if (val === '') return options?.default ?? false;
+  throw new TypeError(
+    `Input does not meet YAML 1.2 "Core Schema" specification: ${name}\n` +
+      `Support boolean input list: \`true | True | TRUE | false | False | FALSE\``,
+  );
+}
+
+// O_NOFOLLOW is undefined on Windows. This sets it to 0 if it's not defined.
+const O_NOFOLLOW: number = (fs.constants as { O_NOFOLLOW?: number }).O_NOFOLLOW ?? 0;
+
+export function isAllowListed(filePath: string): boolean {
+  // Kubelet projects service-account tokens through a symlink chain
+  // (token -> ..data/token, ..data -> ..<timestamp>/). The containing path is
+  // kubelet-controlled, so we allow symlink-following reads of this fixed
+  // location only.
+  const KUBERNETES_TOKEN_PATH_REGEX = /^\/var\/run\/secrets\/[^/]+\/serviceaccount\/token$/;
+
+  if (process.platform !== 'win32') {
+    // No Kubernetes token paths on Windows
+    return KUBERNETES_TOKEN_PATH_REGEX.test(path.posix.normalize(filePath));
+  }
+  return false;
+}
+
+export function isSymlink(filePath: string): boolean {
+  try {
+    return fs.lstatSync(filePath).isSymbolicLink();
+  } catch (err) {
+    if ((err as NodeJS.ErrnoException).code === 'ENOENT') return false;
+    throw err;
+  }
+}
+
+// Refuses if filePath or its parent directory is a symbolic link.
+function refuseSymlinkOnPath(filePath: string): void {
+  const parent = path.dirname(filePath);
+  if (parent !== filePath && isSymlink(parent)) {
+    throw new Error(`Refusing ${filePath} (parent directory is a symbolic link)`);
+  }
+  if (isSymlink(filePath)) {
+    throw new Error(`Refusing ${filePath} (path is a symbolic link)`);
+  }
+}
+
+function assertRegularFile(fd: number, filePath: string): void {
+  const stats = fs.fstatSync(fd);
+  if (!stats.isFile()) {
+    throw new Error(`${filePath} (path is not a regular file)`);
+  }
+}
+
+// ENOENT: file does not exist
+// ELOOP: too many symbolic links (from NOFOLLOW)
+
+export function readFileUtf8(filePath: string): string | null {
+  const allowSymlink = isAllowListed(filePath);
+  if (!allowSymlink) {
+    refuseSymlinkOnPath(filePath);
+  }
+  const openFlags = fs.constants.O_RDONLY | (allowSymlink ? 0 : O_NOFOLLOW);
+  let fd: number;
+  try {
+    fd = fs.openSync(filePath, openFlags);
+  } catch (err) {
+    const code = (err as NodeJS.ErrnoException).code;
+    if (code === 'ENOENT') return null;
+    if (code === 'ELOOP') {
+      throw new Error(`Refusing ${filePath} (path is a symbolic link)`);
+    }
+    throw err;
+  }
+  try {
+    assertRegularFile(fd, filePath);
+    return fs.readFileSync(fd, 'utf-8');
+  } finally {
+    fs.closeSync(fd);
+  }
+}
+
+export function writeFileUtf8(filePath: string, content: string, mode = 0o600): void {
+  refuseSymlinkOnPath(filePath);
+  let fd: number;
+  try {
+    fd = fs.openSync(filePath, fs.constants.O_WRONLY | fs.constants.O_CREAT | fs.constants.O_TRUNC | O_NOFOLLOW, mode);
+  } catch (err) {
+    if ((err as NodeJS.ErrnoException).code === 'ELOOP') {
+      throw new Error(`Refusing ${filePath} (path is a symbolic link)`);
+    }
+    throw err;
+  }
+  try {
+    assertRegularFile(fd, filePath);
+    // openSync only applies mode on creation.
+    // If the file already exists, we need to ensure the mode is correct.
+    if (process.platform !== 'win32') {
+      fs.fchmodSync(fd, mode);
+    }
+    fs.writeFileSync(fd, content);
+  } finally {
+    fs.closeSync(fd);
+  }
+}
+
+export function mkdir(dir: string, mode = 0o700): void {
+  fs.mkdirSync(dir, { recursive: true, mode });
+  if (isSymlink(dir)) {
+    throw new Error(`Refusing ${dir} (path is a symbolic link)`);
+  }
+}
@@ -8,82 +8,97 @@ import {
  exportAccountId,
  exportCredentials,
  exportRegion,
+  getBooleanInput,
  retryAndBackoff,
+  toCredentialIdentity,
  translateEnvVariables,
  unsetCredentials,
+  validateAccountId,
  verifyKeys,
 } from './helpers';
+import { writeProfileFiles } from './profileManager';

 const DEFAULT_ROLE_DURATION = 3600; // One hour (seconds)
 const ROLE_SESSION_NAME = 'GitHubActions';
 const REGION_REGEX = /^[a-z0-9-]+$/g;
+const ROLE_SESSION_NAME_REGEX = /^[\w+=,.@-]*$/;

 export async function run() {
  try {
    translateEnvVariables();
    // Get inputs
+    // Undefined inputs are empty strings ( or empty arrays)
    const AccessKeyId = core.getInput('aws-access-key-id', { required: false });
-    const SecretAccessKey = core.getInput('aws-secret-access-key', {
-      required: false,
-    });
-    const sessionTokenInput = core.getInput('aws-session-token', {
-      required: false,
-    });
+    const SecretAccessKey = core.getInput('aws-secret-access-key', { required: false });
+    const sessionTokenInput = core.getInput('aws-session-token', { required: false });
    const SessionToken = sessionTokenInput === '' ? undefined : sessionTokenInput;
    const region = core.getInput('aws-region', { required: true });
+    const awsProfile = core.getInput('aws-profile', { required: false });
+    const overwriteAwsProfile = getBooleanInput('overwrite-aws-profile', { required: false });
    const roleToAssume = core.getInput('role-to-assume', { required: false });
    const audience = core.getInput('audience', { required: false });
-    const maskAccountIdInput = core.getInput('mask-aws-account-id', { required: false }) || 'false';
-    const maskAccountId = maskAccountIdInput.toLowerCase() === 'true';
-    const roleExternalId = core.getInput('role-external-id', {
-      required: false,
-    });
-    const webIdentityTokenFile = core.getInput('web-identity-token-file', {
-      required: false,
-    });
+    const maskAccountId = getBooleanInput('mask-aws-account-id', { required: false });
+    const roleExternalId = core.getInput('role-external-id', { required: false });
+    const webIdentityTokenFile = core.getInput('web-identity-token-file', { required: false });
    const roleDuration =
      Number.parseInt(core.getInput('role-duration-seconds', { required: false })) || DEFAULT_ROLE_DURATION;
    const roleSessionName = core.getInput('role-session-name', { required: false }) || ROLE_SESSION_NAME;
-    const roleSkipSessionTaggingInput = core.getInput('role-skip-session-tagging', { required: false }) || 'false';
-    const roleSkipSessionTagging = roleSkipSessionTaggingInput.toLowerCase() === 'true';
+    const roleSkipSessionTagging = getBooleanInput('role-skip-session-tagging', { required: false });
+    const transitiveTagKeys = core.getMultilineInput('transitive-tag-keys', { required: false });
    const proxyServer = core.getInput('http-proxy', { required: false }) || process.env.HTTP_PROXY;
-    const inlineSessionPolicy = core.getInput('inline-session-policy', {
-      required: false,
+    const customTags = core.getInput('custom-tags', { required: false });
+    const inlineSessionPolicy = core.getInput('inline-session-policy', { required: false });
+    const managedSessionPolicies = core.getMultilineInput('managed-session-policies', { required: false }).map((p) => {
+      return { arn: p };
    });
-    const managedSessionPoliciesInput = core.getMultilineInput('managed-session-policies', { required: false });
-    const managedSessionPolicies: { arn: string }[] = [];
-    const roleChainingInput = core.getInput('role-chaining', { required: false }) || 'false';
-    const roleChaining = roleChainingInput.toLowerCase() === 'true';
-    const outputCredentialsInput = core.getInput('output-credentials', { required: false }) || 'false';
-    const outputCredentials = outputCredentialsInput.toLowerCase() === 'true';
-    const outputEnvCredentialsInput = core.getInput('output-env-credentials', { required: false }) || 'true';
-    const outputEnvCredentials = outputEnvCredentialsInput.toLowerCase() === 'true';
-    const unsetCurrentCredentialsInput = core.getInput('unset-current-credentials', { required: false }) || 'false';
-    const unsetCurrentCredentials = unsetCurrentCredentialsInput.toLowerCase() === 'true';
-    const disableRetryInput = core.getInput('disable-retry', { required: false }) || 'false';
-    let disableRetry = disableRetryInput.toLowerCase() === 'true';
-    const specialCharacterWorkaroundInput =
-      core.getInput('special-characters-workaround', { required: false }) || 'false';
-    const specialCharacterWorkaround = specialCharacterWorkaroundInput.toLowerCase() === 'true';
-    const useExistingCredentialsInput = core.getInput('use-existing-credentials', { required: false }) || 'false';
-    const useExistingCredentials = useExistingCredentialsInput.toLowerCase() === 'true';
+    const roleChaining = getBooleanInput('role-chaining', { required: false });
+    const outputCredentials = getBooleanInput('output-credentials', { required: false });
+    // Default to always outputting environment credentials unless profile is specified. If profile is specified, default
+    // to no environment credentials (but still output them if the user specifically requests it).
+    const outputEnvCredentials = getBooleanInput('output-env-credentials', { required: false, default: !awsProfile });
+    const unsetCurrentCredentials = getBooleanInput('unset-current-credentials', { required: false });
+    let disableRetry = getBooleanInput('disable-retry', { required: false });
+    const specialCharacterWorkaround = getBooleanInput('special-characters-workaround', { required: false });
+    const useExistingCredentials = core.getInput('use-existing-credentials', { required: false });
    let maxRetries = Number.parseInt(core.getInput('retry-max-attempts', { required: false })) || 12;
-    switch (true) {
-      case specialCharacterWorkaround:
-        // 😳
-        disableRetry = false;
-        maxRetries = 12;
-        break;
-      case maxRetries < 1:
-        maxRetries = 1;
-        break;
+    const expectedAccountIds = core
+      .getInput('allowed-account-ids', { required: false })
+      .split(',')
+      .map((s) => s.trim());
+    const forceSkipOidc = getBooleanInput('force-skip-oidc', { required: false });
+    const noProxy = core.getInput('no-proxy', { required: false });
+    const stsEndpoint = core.getInput('sts-endpoint', { required: false });
+    const globalTimeout = Number.parseInt(core.getInput('action-timeout-s', { required: false })) || 0;
+
+    let timeoutId: NodeJS.Timeout | undefined;
+    if (globalTimeout > 0) {
+      core.info(`Setting a global timeout of ${globalTimeout} seconds for the action`);
+      timeoutId = setTimeout(() => {
+        core.setFailed(`Action timed out after ${globalTimeout} seconds`);
+        process.exit(1);
+      }, globalTimeout * 1000);
    }
-    for (const managedSessionPolicy of managedSessionPoliciesInput) {
-      managedSessionPolicies.push({ arn: managedSessionPolicy });
+
+    if (forceSkipOidc && roleToAssume && !AccessKeyId && !webIdentityTokenFile) {
+      throw new Error(
+        "If 'force-skip-oidc' is true and 'role-to-assume' is set, 'aws-access-key-id' or 'web-identity-token-file' must be set",
+      );
    }

+    if (specialCharacterWorkaround) {
+      // 😳
+      disableRetry = false;
+      maxRetries = 12;
+    } else if (maxRetries < 1) {
+      maxRetries = 1;
+    }
+
+    const withRetry = <T>(fn: () => Promise<T>, label: string): Promise<T> =>
+      retryAndBackoff(fn, !disableRetry, maxRetries, 0, 50, label);
+
    // Logic to decide whether to attempt to use OIDC or not
    const useGitHubOIDCProvider = () => {
+      if (forceSkipOidc) return false;
      // The `ACTIONS_ID_TOKEN_REQUEST_TOKEN` environment variable is set when the `id-token` permission is granted.
      // This is necessary to authenticate with OIDC, but not strictly set just for OIDC. If it is not set and all other
      // checks pass, it is likely but not guaranteed that the user needs but lacks this permission in their workflow.
@@ -116,10 +131,35 @@ export async function run() {
    if (!region.match(REGION_REGEX)) {
      throw new Error(`Region is not valid: ${region}`);
    }
+
+    if (roleSessionName.length < 2 || roleSessionName.length > 64) {
+      throw new Error(
+        `Role session name must be between 2 and 64 characters, got ${roleSessionName.length}: '${roleSessionName}'`,
+      );
+    }
+    if (!roleSessionName.match(ROLE_SESSION_NAME_REGEX)) {
+      throw new Error(
+        `Role session name is not valid: '${roleSessionName}'. Must satisfy regular expression pattern: [\\w+=,.@-]*`,
+      );
+    }
+
    exportRegion(region, outputEnvCredentials);

    // Instantiate credentials client
-    const credentialsClient = new CredentialsClient({ region, proxyServer });
+    const clientProps: {
+      region: string;
+      proxyServer?: string;
+      noProxy?: string;
+      stsEndpoint?: string;
+      roleChaining: boolean;
+    } = {
+      region,
+      roleChaining,
+    };
+    if (proxyServer) clientProps.proxyServer = proxyServer;
+    if (noProxy) clientProps.noProxy = noProxy;
+    if (stsEndpoint) clientProps.stsEndpoint = stsEndpoint;
+    const credentialsClient = new CredentialsClient(clientProps);
    let sourceAccountId: string;
    let webIdentityToken: string;

@@ -128,6 +168,7 @@ export async function run() {
      const validCredentials = await areCredentialsValid(credentialsClient);
      if (validCredentials) {
        core.notice('Pre-existing credentials are valid. No need to generate new ones.');
+        if (timeoutId) clearTimeout(timeoutId);
        return;
      }
      core.notice('No valid credentials exist. Running as normal.');
@@ -137,13 +178,9 @@ export async function run() {
    // Else, export credentials provided as input
    if (useGitHubOIDCProvider()) {
      try {
-        webIdentityToken = await retryAndBackoff(
-          async () => {
-            return core.getIDToken(audience);
-          },
-          !disableRetry,
-          maxRetries,
-        );
+        webIdentityToken = await withRetry(async () => {
+          return core.getIDToken(audience);
+        }, 'getIDToken');
      } catch (error) {
        throw new Error(`getIDToken call failed: ${errorMessage(error)}`);
      }
@@ -156,64 +193,122 @@ export async function run() {
      // the source credentials to already be masked as secrets
      // in any error messages.
      exportCredentials({ AccessKeyId, SecretAccessKey, SessionToken }, outputCredentials, outputEnvCredentials);
+
+      // If using IAM User Credentials, write to profile now so that the assumeRole call can succeed (and also for
+      // credential validation before role assumption).
+      if (awsProfile) {
+        writeProfileFiles(awsProfile, { AccessKeyId, SecretAccessKey, SessionToken }, region, overwriteAwsProfile);
+      }
    } else if (!webIdentityTokenFile && !roleChaining) {
-      // Proceed only if credentials can be picked up
-      await credentialsClient.validateCredentials();
-      sourceAccountId = await exportAccountId(credentialsClient, maskAccountId);
+      // Proceed only if credentials can be picked up. validateCredentials resolves the ambient
+      // credentials via the SDK default chain, proves they work, and returns the caller identity.
+      const identity = await withRetry(
+        () => credentialsClient.validateCredentials(undefined, undefined, roleChaining),
+        'validateCredentials',
+      );
+      // Enforce the allowed-account-ids guardrail unless a role will be assumed, in which case the
+      // final account is validated after assumeRole (these ambient credentials are the source account).
+      if (!roleToAssume) {
+        validateAccountId(expectedAccountIds, identity.Account);
+      }
+      sourceAccountId = exportAccountId(identity, maskAccountId);
    }

    if (AccessKeyId || roleChaining) {
-      // Validate that the SDK can actually pick up credentials.
-      // This validates cases where this action is using existing environment credentials,
-      // and cases where the user intended to provide input credentials but the secrets inputs resolved to empty strings.
-      await credentialsClient.validateCredentials(AccessKeyId, roleChaining);
-      sourceAccountId = await exportAccountId(credentialsClient, maskAccountId);
+      // Validate that the credentials the action will use actually work, and resolve their identity.
+      const resolutionCredentials =
+        outputEnvCredentials || !AccessKeyId
+          ? undefined
+          : toCredentialIdentity({ AccessKeyId, SecretAccessKey, SessionToken });
+      const identity = await withRetry(
+        () => credentialsClient.validateCredentials(resolutionCredentials, AccessKeyId, roleChaining),
+        'validateCredentials',
+      );
+      // Enforce the allowed-account-ids guardrail unless a role will be assumed (the final account is
+      // validated after assumeRole; these are the source credentials).
+      if (!roleToAssume) {
+        validateAccountId(expectedAccountIds, identity.Account);
+      }
+      sourceAccountId = identity.Account;
+      if (outputEnvCredentials) {
+        exportAccountId(identity, maskAccountId);
+      }
+    }
+    if (customTags && (useGitHubOIDCProvider() || webIdentityTokenFile)) {
+      core.warning(
+        "'custom-tags' is set but will be ignored because session tags cannot be applied when using OIDC or web identity token authentication. " +
+          'Tags are controlled by the identity provider token claims in these authentication flows.',
+      );
    }

    // Get role credentials if configured to do so
    if (roleToAssume) {
      let roleCredentials: AssumeRoleCommandOutput;
      do {
-        roleCredentials = await retryAndBackoff(
-          async () => {
-            return assumeRole({
-              credentialsClient,
-              sourceAccountId,
-              roleToAssume,
-              roleExternalId,
-              roleDuration,
-              roleSessionName,
-              roleSkipSessionTagging,
-              webIdentityTokenFile,
-              webIdentityToken,
-              inlineSessionPolicy,
-              managedSessionPolicies,
-            });
-          },
-          !disableRetry,
-          maxRetries,
-        );
+        roleCredentials = await withRetry(async () => {
+          return assumeRole({
+            credentialsClient,
+            sourceAccountId,
+            roleToAssume,
+            roleExternalId,
+            roleDuration,
+            roleSessionName,
+            roleSkipSessionTagging,
+            transitiveTagKeys,
+            webIdentityTokenFile,
+            webIdentityToken,
+            inlineSessionPolicy,
+            managedSessionPolicies,
+            customTags,
+          });
+        }, 'AssumeRole');
      } while (specialCharacterWorkaround && !verifyKeys(roleCredentials.Credentials));
      core.info(`Authenticated as assumedRoleId ${roleCredentials.AssumedRoleUser?.AssumedRoleId}`);
      exportCredentials(roleCredentials.Credentials, outputCredentials, outputEnvCredentials);
-      // We need to validate the credentials in 2 of our use-cases
-      // First: self-hosted runners. If the GITHUB_ACTIONS environment variable
-      //  is set to `true` then we are NOT in a self-hosted runner.
-      // Second: Customer provided credentials manually (IAM User keys stored in GH Secrets)
-      if (!process.env.GITHUB_ACTIONS || AccessKeyId) {
-        await credentialsClient.validateCredentials(roleCredentials.Credentials?.AccessKeyId);
-      }
+      // Validate the assumed-role credentials and resolve their identity.
+      const identity = await withRetry(
+        () => credentialsClient.validateCredentials(toCredentialIdentity(roleCredentials.Credentials)),
+        'validateCredentials',
+      );
+      // Enforce the allowed-account-ids guardrail against the assumed (final) account.
+      validateAccountId(expectedAccountIds, identity.Account);
      if (outputEnvCredentials) {
-        await exportAccountId(credentialsClient, maskAccountId);
+        exportAccountId(identity, maskAccountId);
+      }
+
+      // Write profile files if profile mode is enabled
+      if (awsProfile) {
+        if (!roleCredentials.Credentials) {
+          throw new Error('AssumeRole call succeeded but returned no credentials');
+        }
+        // If user provided IAM User Credentials and then we assumed a role, overwrite the profile file to add
+        // the session token. (this only overwrites the profile within a single run of the action).
+        if (AccessKeyId || !process.env.GITHUB_ACTIONS) {
+          writeProfileFiles(awsProfile, roleCredentials.Credentials, region, true);
+        } else {
+          writeProfileFiles(awsProfile, roleCredentials.Credentials, region, overwriteAwsProfile);
+        }
+
+        if (outputEnvCredentials) {
+          core.exportVariable('AWS_PROFILE', awsProfile);
+        }
      }
    } else {
      core.info('Proceeding with IAM user credentials');
+
+      if (awsProfile) {
+        if (outputEnvCredentials) {
+          core.exportVariable('AWS_PROFILE', awsProfile);
+        }
+      }
    }
+
+    // Clear timeout on successful completion
+    if (timeoutId) clearTimeout(timeoutId);
  } catch (error) {
    core.setFailed(errorMessage(error));

    const showStackTrace = process.env.SHOW_STACK_TRACE;
-
    if (showStackTrace === 'true') {
      throw error;
    }
@@ -0,0 +1,206 @@
+import * as os from 'node:os';
+import * as path from 'node:path';
+import * as core from '@actions/core';
+import type { Credentials } from '@aws-sdk/client-sts';
+import { mkdir, readFileUtf8, writeFileUtf8 } from './helpers';
+
+/**
+ * Parse an INI-format string into a nested object.
+ * Preserves literal section names (e.g. "profile dev" stays as-is).
+ */
+export function parseIni(iniData: string): Record<string, Record<string, string>> {
+  const result: Record<string, Record<string, string>> = {};
+  let currentSection: string | undefined;
+
+  for (const line of iniData.split(/\r?\n/)) {
+    const trimmed = line.trim();
+    if (!trimmed || trimmed.startsWith(';') || trimmed.startsWith('#')) {
+      continue;
+    }
+
+    const sectionMatch = trimmed.match(/^\[([^\]]*)\]$/);
+    if (sectionMatch) {
+      currentSection = sectionMatch[1] as string;
+      if (currentSection === '__proto__') {
+        currentSection = undefined;
+        continue;
+      }
+      result[currentSection] = result[currentSection] || {};
+      continue;
+    }
+
+    if (currentSection) {
+      const eqIndex = trimmed.indexOf('=');
+      if (eqIndex > 0) {
+        const key = trimmed.substring(0, eqIndex).trim();
+        const value = trimmed.substring(eqIndex + 1).trim();
+        if (key !== '__proto__') {
+          const section = result[currentSection];
+          if (section) {
+            section[key] = value;
+          }
+        }
+      }
+    }
+  }
+
+  return result;
+}
+
+/**
+ * Serialize a nested object into INI-format string.
+ */
+export function stringifyIni(data: Record<string, Record<string, string>>): string {
+  const sections: string[] = [];
+  for (const [sectionName, sectionData] of Object.entries(data)) {
+    const lines: string[] = [`[${sectionName}]`];
+    for (const [key, value] of Object.entries(sectionData)) {
+      lines.push(`${key} = ${value}`);
+    }
+    sections.push(lines.join('\n'));
+  }
+  return `${sections.join('\n\n')}\n`;
+}
+
+interface ProfileFilePaths {
+  credentials: string;
+  config: string;
+}
+
+/**
+ * Get the file paths for AWS credentials and config files
+ * Respects AWS_SHARED_CREDENTIALS_FILE and AWS_CONFIG_FILE environment variables
+ */
+export function getProfileFilePaths(): ProfileFilePaths {
+  const credentialsPath = process.env.AWS_SHARED_CREDENTIALS_FILE || path.join(os.homedir(), '.aws', 'credentials');
+  const configPath = process.env.AWS_CONFIG_FILE || path.join(os.homedir(), '.aws', 'config');
+
+  return {
+    credentials: credentialsPath,
+    config: configPath,
+  };
+}
+
+/**
+ * Ensure the AWS directory exists with secure permissions
+ * Creates the directory with 700 permissions (rwx for owner only)
+ */
+export function ensureAwsDirectoryExists(filePath: string): void {
+  const dir = path.dirname(filePath);
+  core.debug(`Ensuring directory exists: ${dir}`);
+  mkdir(dir, 0o700);
+}
+
+/**
+ * Validate profile name format
+ * Profile names must be non-empty, contain no whitespace, brackets, or path separators
+ */
+export function validateProfileName(profileName: string): void {
+  if (!profileName || profileName.trim() === '') {
+    throw new Error('aws-profile must not be empty');
+  }
+
+  if (/\s/.test(profileName)) {
+    throw new Error('aws-profile must not contain whitespace');
+  }
+
+  // INI section names can't contain brackets
+  if (/[[\]]/.test(profileName)) {
+    throw new Error('aws-profile must not contain brackets');
+  }
+
+  // Prevent path traversal
+  if (profileName.includes('/') || profileName.includes('\\')) {
+    throw new Error('aws-profile must not contain path separators');
+  }
+}
+
+/**
+ * Merge a profile section into an INI file
+ * Reads existing file, updates the specified section, and writes back
+ */
+export function mergeProfileSection(
+  filePath: string,
+  sectionName: string,
+  data: Record<string, string>,
+  overwriteAwsProfile: boolean,
+): void {
+  const fileContent = readFileUtf8(filePath);
+  const existingContent: Record<string, Record<string, string>> = fileContent === null ? {} : parseIni(fileContent);
+
+  if (existingContent[sectionName] && !overwriteAwsProfile) {
+    throw new Error(
+      `Profile with name "${sectionName}" already exists. Please use the overwrite-aws-profile input if you want to overwrite existing profiles.`,
+    );
+  }
+  // Merge: update existing profile or add new one
+  existingContent[sectionName] = data;
+
+  const content = stringifyIni(existingContent);
+
+  core.debug(`Writing profile to ${filePath}`);
+  writeFileUtf8(filePath, content, 0o600);
+}
+
+/**
+ * Write AWS profile files with credentials and configuration
+ * This is the main entry point for profile file operations
+ *
+ * @param profileName - Name of the AWS profile to configure
+ * @param credentials - AWS credentials (access key, secret key, session token)
+ * @param region - AWS region
+ */
+export function writeProfileFiles(
+  profileName: string,
+  credentials: Partial<Credentials>,
+  region: string,
+  overwriteAwsProfile: boolean,
+): void {
+  try {
+    // Validate profile name
+    validateProfileName(profileName);
+
+    const paths = getProfileFilePaths();
+
+    // Ensure .aws directory exists
+    ensureAwsDirectoryExists(paths.credentials);
+    ensureAwsDirectoryExists(paths.config);
+
+    // Prepare credentials data
+    const credentialsData: Record<string, string> = {};
+    if (credentials.AccessKeyId) {
+      credentialsData.aws_access_key_id = credentials.AccessKeyId;
+    }
+    if (credentials.SecretAccessKey) {
+      credentialsData.aws_secret_access_key = credentials.SecretAccessKey;
+    }
+    if (credentials.SessionToken) {
+      credentialsData.aws_session_token = credentials.SessionToken;
+    }
+
+    // Credentials file uses [profileName] syntax
+    const credsSectionName = profileName;
+
+    // Config file uses [profile profileName] syntax, except for 'default'
+    const configSectionName = profileName === 'default' ? 'default' : `profile ${profileName}`;
+
+    // Prepare config data
+    const configData: Record<string, string> = {
+      region: region,
+    };
+
+    // Write to credentials file
+    core.info(`Writing credentials to profile: ${profileName}`);
+    mergeProfileSection(paths.credentials, credsSectionName, credentialsData, overwriteAwsProfile);
+
+    // Write to config file
+    core.info(`Writing config to profile: ${profileName}`);
+    mergeProfileSection(paths.config, configSectionName, configData, overwriteAwsProfile);
+
+    core.info(`✓ Successfully configured AWS profile: ${profileName}`);
+  } catch (error) {
+    throw new Error(
+      `Failed to write AWS profile '${profileName}': ${error instanceof Error ? error.message : String(error)}`,
+    );
+  }
+}
@@ -0,0 +1,100 @@
+import type * as http from 'node:http';
+import { describe, expect, test } from 'vitest';
+import { type ProxyOptions, ProxyResolver } from '../src/ProxyResolver';
+
+describe('ProxyResolver', () => {
+  const mockReq = {} as http.ClientRequest;
+
+  test('returns http proxy for http URLs', () => {
+    const options: ProxyOptions = { httpProxy: 'http://proxy:8080' };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('http://proxy:8080');
+  });
+
+  test('returns https proxy for https URLs', () => {
+    const options: ProxyOptions = { httpsProxy: 'https://proxy:8080' };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('https://example.com', mockReq)).toBe('https://proxy:8080');
+  });
+
+  test('returns empty string when no proxy configured', () => {
+    const resolver = new ProxyResolver({});
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+  });
+
+  test('respects noProxy setting', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: 'example.com',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://other.com', mockReq)).toBe('http://proxy:8080');
+  });
+
+  test('handles invalid URLs', () => {
+    const resolver = new ProxyResolver({ httpProxy: 'http://proxy:8080' });
+
+    expect(resolver.getProxyForUrl('invalid-url', mockReq)).toBe('');
+  });
+
+  test('handles wildcard noProxy', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: '*',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+  });
+
+  test('handles comma-separated noProxy list', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: 'example.com,test.com',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://test.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://other.com', mockReq)).toBe('http://proxy:8080');
+  });
+
+  test('handles port-specific noProxy', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: 'example.com:80',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://example.com:8080', mockReq)).toBe('http://proxy:8080');
+  });
+
+  test('handles wildcard domain noProxy', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: '*.example.com',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://sub.example.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('http://proxy:8080');
+    expect(resolver.getProxyForUrl('http://other.com', mockReq)).toBe('http://proxy:8080');
+  });
+
+  test('handles empty noProxy entries', () => {
+    const options: ProxyOptions = {
+      httpProxy: 'http://proxy:8080',
+      noProxy: 'example.com, ,test.com',
+    };
+    const resolver = new ProxyResolver(options);
+
+    expect(resolver.getProxyForUrl('http://example.com', mockReq)).toBe('');
+    expect(resolver.getProxyForUrl('http://test.com', mockReq)).toBe('');
+  });
+});
@@ -0,0 +1,63 @@
+import * as core from '@actions/core';
+import { AssumeRoleWithWebIdentityCommand, GetCallerIdentityCommand, STSClient } from '@aws-sdk/client-sts';
+import { mockClient } from 'aws-sdk-client-mock';
+import { fs, vol } from 'memfs';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import * as helpers from '../src/helpers';
+import { run } from '../src/index';
+import mocks from './mockinputs.test';
+
+vi.mock('node:fs');
+vi.mock('@actions/core');
+
+const mockedSTSClient = mockClient(STSClient);
+
+describe('assumeRoleWithWebIdentityTokenFile', {}, () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+    vi.clearAllMocks();
+    mockedSTSClient.reset();
+    vol.reset();
+    helpers.withsleep(() => Promise.resolve());
+    vi.mocked(core.getInput).mockImplementation(mocks.getInput(mocks.WEBIDENTITY_TOKEN_FILE_INPUTS));
+    vi.mocked(core.getMultilineInput).mockReturnValue([]);
+    mockedSTSClient.on(GetCallerIdentityCommand).resolves({ ...mocks.outputs.GET_CALLER_IDENTITY });
+    process.env = { ...mocks.envs };
+    fs.mkdirSync('/home/github', { recursive: true });
+  });
+
+  afterEach(() => {
+    helpers.reset();
+  });
+
+  it('refuses when the token file is a symlink and never calls STS', async () => {
+    fs.mkdirSync('/etc', { recursive: true });
+    fs.writeFileSync('/etc/passwd', 'root:x:0:0::/root:/bin/sh');
+    fs.symlinkSync('/etc/passwd', '/home/github/file.txt');
+
+    await run();
+
+    expect(core.setFailed).toHaveBeenCalledWith(expect.stringMatching(/Refusing .* \(.* symbolic link\)/));
+    expect(mockedSTSClient.commandCalls(AssumeRoleWithWebIdentityCommand)).toHaveLength(0);
+    expect(fs.readFileSync('/etc/passwd', 'utf-8')).toBe('root:x:0:0::/root:/bin/sh');
+  });
+
+  it('preserves the existing missing-file error when the token file does not exist', async () => {
+    await run();
+
+    expect(core.setFailed).toHaveBeenCalledWith(expect.stringContaining('Web identity token file does not exist'));
+    expect(mockedSTSClient.commandCalls(AssumeRoleWithWebIdentityCommand)).toHaveLength(0);
+  });
+
+  it('passes token contents to STS when the file is regular', async () => {
+    fs.writeFileSync('/home/github/file.txt', 'real-token');
+    mockedSTSClient.on(AssumeRoleWithWebIdentityCommand).resolves(mocks.outputs.STS_CREDENTIALS);
+
+    await run();
+
+    expect(core.setFailed).not.toHaveBeenCalled();
+    const calls = mockedSTSClient.commandCalls(AssumeRoleWithWebIdentityCommand);
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.args[0].input.WebIdentityToken).toBe('real-token');
+  });
+});
@@ -5,20 +5,15 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { cleanup } from '../src/cleanup';
 import mocks from './mockinputs.test';

+vi.mock('@actions/core');
+
 const mockedSTSClient = mockClient(STSClient);

 describe('Configure AWS Credentials cleanup', {}, () => {
  beforeEach(() => {
-    // Reset mock state
-    vi.restoreAllMocks();
+    vi.resetAllMocks();
    mockedSTSClient.reset();
-    // Mock GitHub Actions core functions
-    vi.spyOn(core, 'exportVariable').mockImplementation((_n, _v) => {});
-    vi.spyOn(core, 'setSecret').mockImplementation((_s) => {});
-    vi.spyOn(core, 'setFailed').mockImplementation((_m) => {});
-    vi.spyOn(core, 'setOutput').mockImplementation((_n, _v) => {});
-    vi.spyOn(core, 'debug').mockImplementation((_m) => {});
-    vi.spyOn(core, 'info').mockImplementation((_m) => {});
+    vi.mocked(core.getInput).mockReturnValue('');
    process.env = {
      ...mocks.envs,
      AWS_ACCESS_KEY_ID: 'CLEANUPTEST',
@@ -38,15 +33,35 @@ describe('Configure AWS Credentials cleanup', {}, () => {
    expect(core.exportVariable).toHaveBeenCalledWith('AWS_DEFAULT_REGION', '');
    expect(core.exportVariable).toHaveBeenCalledWith('AWS_REGION', '');
  });
+  it('also clears AWS_PROFILE when aws-profile was set', {}, () => {
+    vi.mocked(core.getInput).mockImplementation((name: string) => {
+      if (name === 'aws-profile') return 'my-profile';
+      if (name === 'output-env-credentials') return 'true';
+      return '';
+    });
+    cleanup();
+    expect(core.setFailed).toHaveBeenCalledTimes(0);
+    expect(core.exportVariable).toHaveBeenCalledTimes(6);
+    expect(core.exportVariable).toHaveBeenCalledWith('AWS_PROFILE', '');
+  });
+  it('skips env cleanup when aws-profile is set without output-env-credentials', {}, () => {
+    vi.mocked(core.getInput).mockImplementation((name: string) => {
+      if (name === 'aws-profile') return 'my-profile';
+      return '';
+    });
+    cleanup();
+    expect(core.setFailed).toHaveBeenCalledTimes(0);
+    expect(core.exportVariable).toHaveBeenCalledTimes(0);
+  });
  it('handles errors', {}, () => {
-    vi.spyOn(core, 'exportVariable').mockImplementationOnce(() => {
+    vi.mocked(core.exportVariable).mockImplementationOnce(() => {
      throw new Error('Test error');
    });
    cleanup();
    expect(core.setFailed).toHaveBeenCalled();
  });
  it(`doesn't export credentials as empty env variables if asked not to`, {}, () => {
-    vi.spyOn(core, 'getInput').mockImplementation(mocks.getInput(mocks.NO_ENV_CREDS_INPUTS));
+    vi.mocked(core.getInput).mockImplementation(mocks.getInput(mocks.NO_ENV_CREDS_INPUTS));
    cleanup();
    expect(core.exportVariable).toHaveBeenCalledTimes(0);
  });
@@ -1,11 +1,16 @@
-import { beforeEach } from 'node:test';
 import * as core from '@actions/core';
-import { describe, expect, it, vi } from 'vitest';
+import { fs, vol } from 'memfs';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
 import * as helpers from '../src/helpers';

+vi.mock('node:fs');
+vi.mock('@actions/core');
+
 describe('Configure AWS Credentials helpers', {}, () => {
  beforeEach(() => {
    vi.restoreAllMocks();
+    vi.clearAllMocks();
+    vol.reset();
  });
  it('removes brackets from GitHub Actor', {}, () => {
    const actor = 'actor[bot]';
@@ -23,6 +28,29 @@ describe('Configure AWS Credentials helpers', {}, () => {
    await expect(helpers.retryAndBackoff(fn, false)).rejects.toMatch('i am not retryable');
    expect(fn).toHaveBeenCalledTimes(1);
  });
+  it('retries and logs with label at info level', {}, async () => {
+    helpers.withsleep(() => Promise.resolve());
+    const fn = vi.fn().mockRejectedValueOnce(new Error('transient')).mockResolvedValueOnce('success');
+    const result = await helpers.retryAndBackoff(fn, true, 3, 0, 50, 'TestOp');
+    expect(result).toBe('success');
+    expect(fn).toHaveBeenCalledTimes(2);
+    expect(core.info).toHaveBeenCalledWith(expect.stringContaining('Retry TestOp: attempt 1 of 3 failed'));
+    helpers.reset();
+  });
+  it('logs max retries reached with label', {}, async () => {
+    helpers.withsleep(() => Promise.resolve());
+    const fn = vi.fn().mockRejectedValue(new Error('persistent'));
+    await expect(helpers.retryAndBackoff(fn, true, 2, 0, 50, 'TestOp')).rejects.toThrow('persistent');
+    expect(core.info).toHaveBeenCalledWith(expect.stringContaining('Retry TestOp: reached max retries (2)'));
+    helpers.reset();
+  });
+  it('retries without a label (backward compat)', {}, async () => {
+    helpers.withsleep(() => Promise.resolve());
+    const fn = vi.fn().mockRejectedValueOnce(new Error('transient')).mockResolvedValueOnce('ok');
+    await helpers.retryAndBackoff(fn, true, 3);
+    expect(core.info).toHaveBeenCalledWith(expect.stringContaining('Retry: attempt 1 of 3 failed'));
+    helpers.reset();
+  });
  it('can output creds when told to', {}, () => {
    vi.spyOn(core, 'setOutput').mockImplementation(() => {});
    vi.spyOn(core, 'setSecret').mockImplementation(() => {});
@@ -61,4 +89,179 @@ describe('Configure AWS Credentials helpers', {}, () => {
    expect(core.setSecret).toHaveBeenCalledTimes(3);
    expect(core.exportVariable).toHaveBeenCalledTimes(0);
  });
+
+  it('verifies credentials without special characters', {}, () => {
+    expect(helpers.verifyKeys({ AccessKeyId: 'AKIATEST', SecretAccessKey: 'secretkey' })).toBe(true);
+    expect(helpers.verifyKeys({ AccessKeyId: 'AKIA!@#$', SecretAccessKey: 'secret' })).toBe(false);
+    expect(helpers.verifyKeys(undefined)).toBe(false);
+  });
+
+  it('translates environment variables', {}, () => {
+    process.env.AWS_REGION = 'us-east-1';
+    process.env.HTTPS_PROXY = 'https://proxy:8080';
+    helpers.translateEnvVariables();
+    expect(process.env['INPUT_AWS-REGION']).toBe('us-east-1');
+    expect(process.env.HTTP_PROXY).toBe('https://proxy:8080');
+  });
+
+  it('handles getBooleanInput correctly', {}, () => {
+    vi.spyOn(core, 'getInput').mockReturnValue('true');
+    expect(helpers.getBooleanInput('test')).toBe(true);
+
+    vi.spyOn(core, 'getInput').mockReturnValue('false');
+    expect(helpers.getBooleanInput('test')).toBe(false);
+
+    vi.spyOn(core, 'getInput').mockReturnValue('');
+    expect(helpers.getBooleanInput('test', { default: true })).toBe(true);
+
+    vi.spyOn(core, 'getInput').mockReturnValue('invalid');
+    expect(() => helpers.getBooleanInput('test')).toThrow();
+  });
+
+  it('clears session token when not provided', {}, () => {
+    vi.spyOn(core, 'setSecret').mockImplementation(() => {});
+    vi.spyOn(core, 'exportVariable').mockImplementation(() => {});
+    process.env.AWS_SESSION_TOKEN = 'old-token';
+    helpers.exportCredentials({ AccessKeyId: 'test', SecretAccessKey: 'test' }, false, true);
+    expect(core.exportVariable).toHaveBeenCalledWith('AWS_SESSION_TOKEN', '');
+  });
+
+  describe('filesystem helpers', {}, () => {
+    describe('isSymlink', {}, () => {
+      it('returns true for a symlink', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/target', 'data');
+        fs.symlinkSync('/dir/target', '/dir/link');
+        expect(helpers.isSymlink('/dir/link')).toBe(true);
+      });
+
+      it('returns false for a regular file', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/file', 'data');
+        expect(helpers.isSymlink('/dir/file')).toBe(false);
+      });
+
+      it('returns false for a missing path', {}, () => {
+        expect(helpers.isSymlink('/nonexistent')).toBe(false);
+      });
+    });
+
+    describe('readFileUtf8', {}, () => {
+      it('returns content for a regular file', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/file', 'hello');
+        expect(helpers.readFileUtf8('/dir/file')).toBe('hello');
+      });
+
+      it('returns null when the file does not exist', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        expect(helpers.readFileUtf8('/dir/missing')).toBe(null);
+      });
+
+      it('refuses to read through a symlink at the target', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/secret', 'sensitive');
+        fs.symlinkSync('/dir/secret', '/dir/link');
+        expect(() => helpers.readFileUtf8('/dir/link')).toThrow(/Refusing .* \(.* symbolic link\)/);
+      });
+
+      it('refuses to read when the parent directory is a symlink', {}, () => {
+        fs.mkdirSync('/real/.aws', { recursive: true });
+        fs.writeFileSync('/real/.aws/credentials', 'data');
+        fs.mkdirSync('/home', { recursive: true });
+        fs.symlinkSync('/real/.aws', '/home/.aws');
+        expect(() => helpers.readFileUtf8('/home/.aws/credentials')).toThrow(/Refusing .* \(.* symbolic link\)/);
+      });
+
+      it('refuses to read when the path is a directory', {}, () => {
+        fs.mkdirSync('/dir/subdir', { recursive: true });
+        expect(() => helpers.readFileUtf8('/dir/subdir')).toThrow(/not a regular file/);
+      });
+
+      it.skipIf(process.platform === 'win32')(
+        'follows the kubelet projected-token symlink chain at /var/run/secrets/*/serviceaccount/token',
+        () => {
+          fs.mkdirSync('/var/run/secrets/eks.amazonaws.com/serviceaccount/..2026_05_28_00_00_00.123', {
+            recursive: true,
+          });
+          fs.writeFileSync(
+            '/var/run/secrets/eks.amazonaws.com/serviceaccount/..2026_05_28_00_00_00.123/token',
+            'jwt-token',
+          );
+          fs.symlinkSync('..2026_05_28_00_00_00.123', '/var/run/secrets/eks.amazonaws.com/serviceaccount/..data');
+          fs.symlinkSync('..data/token', '/var/run/secrets/eks.amazonaws.com/serviceaccount/token');
+          expect(helpers.readFileUtf8('/var/run/secrets/eks.amazonaws.com/serviceaccount/token')).toBe('jwt-token');
+        },
+      );
+
+      it.skipIf(process.platform === 'win32')('still refuses symlinks at lookalike paths outside the allowlist', () => {
+        fs.mkdirSync('/var/run/secrets/eks.amazonaws.com/serviceaccount', { recursive: true });
+        fs.writeFileSync('/var/run/secrets/eks.amazonaws.com/serviceaccount/secret', 'jwt-token');
+        fs.symlinkSync(
+          '/var/run/secrets/eks.amazonaws.com/serviceaccount/secret',
+          '/var/run/secrets/eks.amazonaws.com/serviceaccount/token2',
+        );
+        expect(() => helpers.readFileUtf8('/var/run/secrets/eks.amazonaws.com/serviceaccount/token2')).toThrow(
+          /Refusing .* \(.* symbolic link\)/,
+        );
+      });
+    });
+
+    describe('isAllowListed', {}, () => {
+      it.skipIf(process.platform === 'win32')('matches the canonical kubelet projected-token path', () => {
+        expect(helpers.isAllowListed('/var/run/secrets/eks.amazonaws.com/serviceaccount/token')).toBe(true);
+        expect(helpers.isAllowListed('/var/run/secrets/kubernetes.io/serviceaccount/token')).toBe(true);
+      });
+
+      it.skipIf(process.platform === 'win32')('rejects nested or unrelated paths', () => {
+        expect(helpers.isAllowListed('/var/run/secrets/serviceaccount/token')).toBe(false);
+        expect(helpers.isAllowListed('/var/run/secrets/a/b/serviceaccount/token')).toBe(false);
+        expect(helpers.isAllowListed('/var/run/secrets/eks.amazonaws.com/serviceaccount/token2')).toBe(false);
+        expect(helpers.isAllowListed('/etc/var/run/secrets/foo/serviceaccount/token')).toBe(false);
+      });
+
+      it.skipIf(process.platform === 'win32')('normalizes path traversal attempts', () => {
+        expect(helpers.isAllowListed('/var/run/secrets/foo/serviceaccount/../../../../etc/passwd')).toBe(false);
+      });
+    });
+
+    describe('writeFileUtf8', {}, () => {
+      it('writes content with the specified mode', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        helpers.writeFileUtf8('/dir/file', 'payload', 0o600);
+        expect(fs.readFileSync('/dir/file', 'utf-8')).toBe('payload');
+        expect(fs.statSync('/dir/file').mode & 0o777).toBe(0o600);
+      });
+
+      it('refuses to follow a symlink at the target and leaves the target file untouched', {}, () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/target', 'original');
+        fs.symlinkSync('/dir/target', '/dir/link');
+        expect(() => helpers.writeFileUtf8('/dir/link', 'attacker', 0o600)).toThrow(/Refusing .* \(.* symbolic link\)/);
+        expect(fs.readFileSync('/dir/target', 'utf-8')).toBe('original');
+      });
+
+      it.skipIf(process.platform === 'win32')('tightens mode on existing files', () => {
+        fs.mkdirSync('/dir', { recursive: true });
+        fs.writeFileSync('/dir/file', 'old', { mode: 0o644 });
+        helpers.writeFileUtf8('/dir/file', 'new', 0o600);
+        expect(fs.statSync('/dir/file').mode & 0o777).toBe(0o600);
+      });
+    });
+
+    describe('mkdir', {}, () => {
+      it('is idempotent on a regular directory', {}, () => {
+        helpers.mkdir('/some/nested/dir', 0o700);
+        helpers.mkdir('/some/nested/dir', 0o700);
+        expect(fs.statSync('/some/nested/dir').isDirectory()).toBe(true);
+      });
+
+      it('refuses when the target directory is a symlink', {}, () => {
+        fs.mkdirSync('/real', { recursive: true });
+        fs.mkdirSync('/home', { recursive: true });
+        fs.symlinkSync('/real', '/home/.aws');
+        expect(() => helpers.mkdir('/home/.aws', 0o700)).toThrow(/Refusing .* \(.* symbolic link\)/);
+      });
+    });
+  });
 });
@@ -6,6 +6,46 @@ const inputs = {
    'aws-region': 'fake-region-1',
    'special-characters-workaround': 'true',
  },
+  CUSTOM_TAGS_INVALID_JSON_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'retry-max-attempts': '1',
+    'custom-tags': 'not a json',
+  },
+  CUSTOM_TAGS_ARRAY_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'retry-max-attempts': '1',
+    'custom-tags': '[1, 2, 3]',
+  },
+  CUSTOM_TAGS_RESERVED_KEY_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'retry-max-attempts': '1',
+    'custom-tags': JSON.stringify({ Repository: 'evil-repo' }),
+  },
+  CUSTOM_TAGS_INVALID_KEY_CHARS_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'retry-max-attempts': '1',
+    'custom-tags': JSON.stringify({ 'invalid{key}': 'value' }),
+  },
+  CUSTOM_TAGS_OBJECT_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'retry-max-attempts': '1',
+    'custom-tags': JSON.stringify({ Environment: 'Production', Team: 'DevOps' }),
+  },
  IAM_USER_INPUTS: {
    'aws-access-key-id': 'MYAWSACCESSKEYID',
    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
@@ -43,6 +83,14 @@ const inputs = {
    'output-env-credentials': 'false',
    'output-credentials': 'true',
  },
+  IAM_ASSUMEROLE_NO_ENV_INPUTS: {
+    'aws-access-key-id': 'MYAWSACCESSKEYID',
+    'aws-secret-access-key': 'MYAWSSECRETACCESSKEY',
+    'role-to-assume': 'arn:aws:iam::111111111111:role/MY-ROLE',
+    'aws-region': 'fake-region-1',
+    'output-env-credentials': 'false',
+    'output-credentials': 'true',
+  },
 };

 const envs = {
@@ -53,6 +101,13 @@ const envs = {
  GITHUB_SHA: 'MY-COMMIT-ID',
  GITHUB_WORKSPACE: '/home/github',
  GITHUB_ACTIONS: 'true',
+  GITHUB_REF: 'refs/pull/42/merge',
+  GITHUB_EVENT_NAME: 'pull_request',
+  GITHUB_RUN_ID: '16412345678',
+  GITHUB_JOB: 'build',
+  GITHUB_BASE_REF: 'main',
+  GITHUB_HEAD_REF: 'feature-branch',
+  GITHUB_TRIGGERING_ACTOR: 'MY-USERNAME[bot]',
 };

 const outputs = {
@@ -0,0 +1,804 @@
+import * as core from '@actions/core';
+import { fs, vol } from 'memfs';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import {
+  ensureAwsDirectoryExists,
+  getProfileFilePaths,
+  mergeProfileSection,
+  parseIni,
+  stringifyIni,
+  validateProfileName,
+  writeProfileFiles,
+} from '../src/profileManager';
+
+vi.mock('node:fs');
+vi.mock('@actions/core');
+
+describe('Profile Manager', {}, () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+    vi.clearAllMocks();
+    vol.reset();
+  });
+
+  describe('parseIni', {}, () => {
+    it('parses a single section', {}, () => {
+      const result = parseIni('[dev]\naws_access_key_id=AKIA\naws_secret_access_key=secret\n');
+      expect(result.dev).toEqual({ aws_access_key_id: 'AKIA', aws_secret_access_key: 'secret' });
+    });
+
+    it('parses multiple sections', {}, () => {
+      const result = parseIni('[dev]\nkey=dev_val\n\n[prod]\nkey=prod_val\n');
+      expect(result.dev.key).toBe('dev_val');
+      expect(result.prod.key).toBe('prod_val');
+    });
+
+    it('skips comments and empty lines', {}, () => {
+      const result = parseIni('# comment\n; another comment\n\n[dev]\nkey=val\n');
+      expect(result.dev).toEqual({ key: 'val' });
+    });
+
+    it('trims whitespace around keys and values', {}, () => {
+      const result = parseIni('[dev]\n  key  =  val  \n');
+      expect(result.dev.key).toBe('val');
+    });
+
+    it('preserves section names with spaces (e.g. profile prefix)', {}, () => {
+      const result = parseIni('[profile dev]\nregion=us-east-1\n');
+      expect(result['profile dev']).toEqual({ region: 'us-east-1' });
+    });
+
+    it('guards against __proto__ section pollution', {}, () => {
+      const result = parseIni('[__proto__]\npolluted=true\n[safe]\nkey=val\n');
+      expect(Object.getPrototypeOf(result)).not.toHaveProperty('polluted');
+      expect(result.safe).toEqual({ key: 'val' });
+    });
+
+    it('guards against __proto__ key pollution', {}, () => {
+      const result = parseIni('[dev]\n__proto__=evil\naws_access_key_id=AKIA\n');
+      expect(result.dev).toEqual({ aws_access_key_id: 'AKIA' });
+      expect(result.dev).not.toHaveProperty('__proto__', 'evil');
+    });
+
+    it('handles values containing equals signs', {}, () => {
+      const result = parseIni('[dev]\naws_session_token=FwoGZXIvYXdzEBYa/base64==\n');
+      expect(result.dev.aws_session_token).toBe('FwoGZXIvYXdzEBYa/base64==');
+    });
+
+    it('handles empty values', {}, () => {
+      const result = parseIni('[dev]\ncli_pager=\n');
+      expect(result.dev.cli_pager).toBe('');
+    });
+
+    it('returns empty object for empty input', {}, () => {
+      expect(parseIni('')).toEqual({});
+    });
+
+    it('returns empty object for whitespace-only input', {}, () => {
+      expect(parseIni('   \n\n  \n')).toEqual({});
+    });
+
+    it('handles Windows line endings (CRLF)', {}, () => {
+      const result = parseIni('[dev]\r\naws_access_key_id=AKIA\r\naws_secret_access_key=secret\r\n');
+      expect(result.dev).toEqual({ aws_access_key_id: 'AKIA', aws_secret_access_key: 'secret' });
+    });
+  });
+
+  describe('stringifyIni', {}, () => {
+    it('serializes a single section', {}, () => {
+      const result = stringifyIni({ dev: { key: 'val' } });
+      expect(result).toBe('[dev]\nkey = val\n');
+    });
+
+    it('serializes multiple sections with blank line separator', {}, () => {
+      const result = stringifyIni({ dev: { a: '1' }, prod: { b: '2' } });
+      expect(result).toBe('[dev]\na = 1\n\n[prod]\nb = 2\n');
+    });
+
+    it('round-trips through parseIni', {}, () => {
+      const data = {
+        dev: { aws_access_key_id: 'AKIA', aws_secret_access_key: 'secret' },
+        'profile prod': { region: 'us-west-2' },
+      };
+      const roundTripped = parseIni(stringifyIni(data));
+      expect(roundTripped).toEqual(data);
+    });
+
+    it('handles empty data object', {}, () => {
+      const result = stringifyIni({});
+      expect(result).toBe('\n');
+      expect(parseIni(result)).toEqual({});
+    });
+
+    it('handles section with no keys', {}, () => {
+      const result = stringifyIni({ dev: {} });
+      expect(result).toBe('[dev]\n');
+    });
+  });
+
+  describe('validateProfileName', {}, () => {
+    it('accepts valid profile names', {}, () => {
+      expect(() => validateProfileName('dev')).not.toThrow();
+      expect(() => validateProfileName('production')).not.toThrow();
+      expect(() => validateProfileName('my-profile-123')).not.toThrow();
+      expect(() => validateProfileName('default')).not.toThrow();
+    });
+
+    it('rejects empty profile names', {}, () => {
+      expect(() => validateProfileName('')).toThrow('aws-profile must not be empty');
+      expect(() => validateProfileName('   ')).toThrow('aws-profile must not be empty');
+    });
+
+    it('rejects profile names with whitespace', {}, () => {
+      expect(() => validateProfileName('my profile')).toThrow('aws-profile must not contain whitespace');
+      expect(() => validateProfileName('dev\ntest')).toThrow('aws-profile must not contain whitespace');
+      expect(() => validateProfileName('prod\tenv')).toThrow('aws-profile must not contain whitespace');
+    });
+
+    it('rejects profile names with brackets', {}, () => {
+      expect(() => validateProfileName('dev[test]')).toThrow('aws-profile must not contain brackets');
+      expect(() => validateProfileName('[profile]')).toThrow('aws-profile must not contain brackets');
+    });
+
+    it('rejects profile names with path separators', {}, () => {
+      expect(() => validateProfileName('dev/test')).toThrow('aws-profile must not contain path separators');
+      expect(() => validateProfileName('dev\\test')).toThrow('aws-profile must not contain path separators');
+      expect(() => validateProfileName('../etc/passwd')).toThrow('aws-profile must not contain path separators');
+    });
+  });
+
+  describe('getProfileFilePaths', {}, () => {
+    it('returns default paths when env vars not set', {}, () => {
+      delete process.env.AWS_SHARED_CREDENTIALS_FILE;
+      delete process.env.AWS_CONFIG_FILE;
+
+      const paths = getProfileFilePaths();
+
+      expect(paths.credentials).toMatch(/\.aws[/\\]credentials$/);
+      expect(paths.config).toMatch(/\.aws[/\\]config$/);
+    });
+
+    it('respects AWS_SHARED_CREDENTIALS_FILE env var', {}, () => {
+      process.env.AWS_SHARED_CREDENTIALS_FILE = '/custom/path/credentials';
+      process.env.AWS_CONFIG_FILE = '/custom/path/config';
+
+      const paths = getProfileFilePaths();
+
+      expect(paths.credentials).toBe('/custom/path/credentials');
+      expect(paths.config).toBe('/custom/path/config');
+    });
+  });
+
+  describe('ensureAwsDirectoryExists', {}, () => {
+    it('creates directory if it does not exist', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+
+      ensureAwsDirectoryExists(filePath);
+
+      expect(fs.existsSync('/home/runner/.aws')).toBe(true);
+    });
+
+    it('does not error if directory already exists', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      expect(() => ensureAwsDirectoryExists(filePath)).not.toThrow();
+    });
+
+    it('creates nested directories', {}, () => {
+      const filePath = '/home/runner/custom/path/.aws/credentials';
+
+      ensureAwsDirectoryExists(filePath);
+
+      expect(fs.existsSync('/home/runner/custom/path/.aws')).toBe(true);
+    });
+  });
+
+  describe('mergeProfileSection', {}, () => {
+    it('creates new file with profile section', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'AKIAIOSFODNN7EXAMPLE',
+          aws_secret_access_key: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
+        },
+        false,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev).toBeDefined();
+      expect(parsed.dev.aws_access_key_id).toBe('AKIAIOSFODNN7EXAMPLE');
+      expect(parsed.dev.aws_secret_access_key).toBe('wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY');
+    });
+
+    it('merges with existing profiles', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      // Create initial profile
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'AKIAIOSFODNN7EXAMPLE',
+          aws_secret_access_key: 'devSecretKey',
+        },
+        false,
+      );
+
+      // Add second profile
+      mergeProfileSection(
+        filePath,
+        'prod',
+        {
+          aws_access_key_id: 'AKIAPRODEXAMPLE',
+          aws_secret_access_key: 'prodSecretKey',
+        },
+        false,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev).toBeDefined();
+      expect(parsed.dev.aws_access_key_id).toBe('AKIAIOSFODNN7EXAMPLE');
+      expect(parsed.prod).toBeDefined();
+      expect(parsed.prod.aws_access_key_id).toBe('AKIAPRODEXAMPLE');
+    });
+
+    it('overwrites existing profile with same name', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      // Create initial profile
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'OLD_KEY',
+          aws_secret_access_key: 'oldSecretKey',
+          aws_session_token: 'oldSessionToken',
+        },
+        false,
+      );
+
+      // Overwrite with new credentials
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'NEW_KEY',
+          aws_secret_access_key: 'newSecretKey',
+          aws_session_token: 'newSessionToken',
+        },
+        true,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev.aws_access_key_id).toBe('NEW_KEY');
+      expect(parsed.dev.aws_secret_access_key).toBe('newSecretKey');
+      expect(parsed.dev.aws_session_token).toBe('newSessionToken');
+    });
+
+    it('overwriting a profile removes stale keys', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      // Create profile with session token
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'AKIA',
+          aws_secret_access_key: 'secret',
+          aws_session_token: 'old-token',
+        },
+        false,
+      );
+
+      // Overwrite without session token
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'AKIA2',
+          aws_secret_access_key: 'secret2',
+        },
+        true,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev.aws_access_key_id).toBe('AKIA2');
+      expect(parsed.dev.aws_secret_access_key).toBe('secret2');
+      expect(parsed.dev.aws_session_token).toBeUndefined();
+    });
+
+    it('handles empty existing file', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+      fs.writeFileSync(filePath, '', { mode: 0o600 });
+
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'AKIA',
+          aws_secret_access_key: 'secret',
+        },
+        false,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev.aws_access_key_id).toBe('AKIA');
+      expect(parsed.dev.aws_secret_access_key).toBe('secret');
+    });
+
+    it('errors if profile name already exists but overwrite flag is false', {}, () => {
+      const filePath = '/home/runner/.aws/credentials';
+      fs.mkdirSync('/home/runner/.aws', { recursive: true });
+
+      // Create initial profile
+      mergeProfileSection(
+        filePath,
+        'dev',
+        {
+          aws_access_key_id: 'OLD_KEY',
+          aws_secret_access_key: 'oldSecretKey',
+        },
+        false,
+      );
+
+      // Overwrite with new credentials
+      expect(() =>
+        mergeProfileSection(
+          filePath,
+          'dev',
+          {
+            aws_access_key_id: 'NEW_KEY',
+            aws_secret_access_key: 'newSecretKey',
+            aws_session_token: 'sessionToken',
+          },
+          false,
+        ),
+      ).toThrow(
+        `Profile with name "dev" already exists. Please use the overwrite-aws-profile input if you want to overwrite existing profiles.`,
+      );
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.dev.aws_access_key_id).toBe('OLD_KEY');
+      expect(parsed.dev.aws_secret_access_key).toBe('oldSecretKey');
+      expect(parsed.dev.aws_session_token).toBeUndefined();
+    });
+  });
+
+  describe('writeProfileFiles', {}, () => {
+    beforeEach(() => {
+      delete process.env.AWS_SHARED_CREDENTIALS_FILE;
+      delete process.env.AWS_CONFIG_FILE;
+    });
+
+    it('writes credentials and config for new profile', {}, () => {
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIAIOSFODNN7EXAMPLE',
+          SecretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
+          SessionToken: 'FwoGZXIvYXdzEBYaDEXAMPLE',
+        },
+        'us-east-1',
+        false,
+      );
+
+      // Check credentials file
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+      const credParsed = parseIni(credContent);
+
+      expect(credParsed.dev).toBeDefined();
+      expect(credParsed.dev.aws_access_key_id).toBe('AKIAIOSFODNN7EXAMPLE');
+      expect(credParsed.dev.aws_secret_access_key).toBe('wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY');
+      expect(credParsed.dev.aws_session_token).toBe('FwoGZXIvYXdzEBYaDEXAMPLE');
+
+      // Check config file
+      const configPath = getProfileFilePaths().config;
+      const configContent = fs.readFileSync(configPath, 'utf-8');
+      const configParsed = parseIni(configContent);
+
+      expect(configParsed['profile dev']).toBeDefined();
+      expect(configParsed['profile dev'].region).toBe('us-east-1');
+    });
+
+    it('uses correct section naming for default profile', {}, () => {
+      writeProfileFiles(
+        'default',
+        {
+          AccessKeyId: 'AKIAIOSFODNN7EXAMPLE',
+          SecretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
+        },
+        'us-west-2',
+        false,
+      );
+
+      // Check credentials file uses [default]
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+      const credParsed = parseIni(credContent);
+
+      expect(credParsed.default).toBeDefined();
+      expect(credParsed['profile default']).toBeUndefined();
+
+      // Check config file uses [default] (not [profile default])
+      const configPath = getProfileFilePaths().config;
+      const configContent = fs.readFileSync(configPath, 'utf-8');
+      const configParsed = parseIni(configContent);
+
+      expect(configParsed.default).toBeDefined();
+      expect(configParsed['profile default']).toBeUndefined();
+    });
+
+    it('supports multiple profiles', {}, () => {
+      // Write first profile
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIADEV',
+          SecretAccessKey: 'devSecret',
+        },
+        'us-east-1',
+        false,
+      );
+
+      // Write second profile
+      writeProfileFiles(
+        'prod',
+        {
+          AccessKeyId: 'AKIAPROD',
+          SecretAccessKey: 'prodSecret',
+          SessionToken: 'prodToken',
+        },
+        'us-west-2',
+        false,
+      );
+
+      // Verify both profiles exist
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+      const credParsed = parseIni(credContent);
+
+      expect(credParsed.dev).toBeDefined();
+      expect(credParsed.prod).toBeDefined();
+      expect(credParsed.dev.aws_access_key_id).toBe('AKIADEV');
+      expect(credParsed.prod.aws_access_key_id).toBe('AKIAPROD');
+    });
+
+    it('handles credentials without session token', {}, () => {
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIAIOSFODNN7EXAMPLE',
+          SecretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
+        },
+        'us-east-1',
+        false,
+      );
+
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+      const credParsed = parseIni(credContent);
+
+      expect(credParsed.dev.aws_access_key_id).toBe('AKIAIOSFODNN7EXAMPLE');
+      expect(credParsed.dev.aws_secret_access_key).toBe('wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY');
+      expect(credParsed.dev.aws_session_token).toBeUndefined();
+    });
+
+    it('throws error for invalid profile name', {}, () => {
+      expect(() =>
+        writeProfileFiles(
+          'invalid profile',
+          {
+            AccessKeyId: 'AKIA',
+            SecretAccessKey: 'secret',
+          },
+          'us-east-1',
+          false,
+        ),
+      ).toThrow('Failed to write AWS profile');
+      expect(() =>
+        writeProfileFiles(
+          'invalid profile',
+          {
+            AccessKeyId: 'AKIA',
+            SecretAccessKey: 'secret',
+          },
+          'us-east-1',
+          false,
+        ),
+      ).toThrow('whitespace');
+    });
+
+    it('respects custom file paths from env vars', {}, () => {
+      process.env.AWS_SHARED_CREDENTIALS_FILE = '/custom/credentials';
+      process.env.AWS_CONFIG_FILE = '/custom/config';
+
+      fs.mkdirSync('/custom', { recursive: true });
+
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIA',
+          SecretAccessKey: 'secret',
+        },
+        'us-east-1',
+        false,
+      );
+
+      expect(fs.existsSync('/custom/credentials')).toBe(true);
+      expect(fs.existsSync('/custom/config')).toBe(true);
+    });
+
+    it('logs info messages', {}, () => {
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIA',
+          SecretAccessKey: 'secret',
+        },
+        'us-east-1',
+        false,
+      );
+
+      expect(core.info).toHaveBeenCalledWith('Writing credentials to profile: dev');
+      expect(core.info).toHaveBeenCalledWith('Writing config to profile: dev');
+      expect(core.info).toHaveBeenCalledWith('✓ Successfully configured AWS profile: dev');
+    });
+
+    it('preserves pre-existing unrelated profiles in credentials file', {}, () => {
+      const credsPath = getProfileFilePaths().credentials;
+      fs.mkdirSync(require('node:path').dirname(credsPath), { recursive: true });
+      fs.writeFileSync(
+        credsPath,
+        '[personal]\naws_access_key_id=AKIAPERSONAL\naws_secret_access_key=personalSecret\naws_session_token=personalToken\n',
+      );
+
+      writeProfileFiles('dev', { AccessKeyId: 'AKIADEV', SecretAccessKey: 'devSecret' }, 'us-east-1', false);
+
+      const content = fs.readFileSync(credsPath, 'utf-8');
+      const parsed = parseIni(content);
+
+      // Pre-existing profile must be fully intact
+      expect(parsed.personal).toEqual({
+        aws_access_key_id: 'AKIAPERSONAL',
+        aws_secret_access_key: 'personalSecret',
+        aws_session_token: 'personalToken',
+      });
+      // New profile also present
+      expect(parsed.dev.aws_access_key_id).toBe('AKIADEV');
+    });
+
+    it('preserves pre-existing config with extra keys', {}, () => {
+      const configPath = getProfileFilePaths().config;
+      fs.mkdirSync(require('node:path').dirname(configPath), { recursive: true });
+      fs.writeFileSync(configPath, '[profile personal]\nregion=eu-west-1\noutput=json\ncli_pager=\n');
+
+      writeProfileFiles('dev', { AccessKeyId: 'AKIA', SecretAccessKey: 'secret' }, 'us-east-1', false);
+
+      const content = fs.readFileSync(configPath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed['profile personal']).toEqual({
+        region: 'eu-west-1',
+        output: 'json',
+        cli_pager: '',
+      });
+      expect(parsed['profile dev'].region).toBe('us-east-1');
+    });
+
+    it('preserves pre-existing default profile when writing a named profile', {}, () => {
+      const credsPath = getProfileFilePaths().credentials;
+      fs.mkdirSync(require('node:path').dirname(credsPath), { recursive: true });
+      fs.writeFileSync(credsPath, '[default]\naws_access_key_id=AKIADEFAULT\naws_secret_access_key=defaultSecret\n');
+
+      writeProfileFiles('dev', { AccessKeyId: 'AKIADEV', SecretAccessKey: 'devSecret' }, 'us-west-2', false);
+
+      const content = fs.readFileSync(credsPath, 'utf-8');
+      const parsed = parseIni(content);
+
+      expect(parsed.default).toEqual({
+        aws_access_key_id: 'AKIADEFAULT',
+        aws_secret_access_key: 'defaultSecret',
+      });
+      expect(parsed.dev.aws_access_key_id).toBe('AKIADEV');
+    });
+
+    it('comments in pre-existing files are stripped on round-trip', {}, () => {
+      const credsPath = getProfileFilePaths().credentials;
+      fs.mkdirSync(require('node:path').dirname(credsPath), { recursive: true });
+      fs.writeFileSync(
+        credsPath,
+        '# My important comment\n[personal]\naws_access_key_id=AKIA\naws_secret_access_key=secret\n',
+      );
+
+      writeProfileFiles('dev', { AccessKeyId: 'AKIADEV', SecretAccessKey: 'devSecret' }, 'us-east-1', false);
+
+      const content = fs.readFileSync(credsPath, 'utf-8') as string;
+
+      // Comment is lost (known trade-off), but profile data is preserved
+      expect(content).not.toContain('# My important comment');
+      const parsed = parseIni(content);
+      expect(parsed.personal.aws_access_key_id).toBe('AKIA');
+      expect(parsed.dev.aws_access_key_id).toBe('AKIADEV');
+    });
+
+    it('writes empty section when credentials object has no keys', {}, () => {
+      writeProfileFiles('dev', {}, 'us-east-1', false);
+
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+      const credParsed = parseIni(credContent);
+
+      // Section exists but has no credential keys
+      expect(credParsed.dev).toEqual({});
+
+      // Config still gets region
+      const configPath = getProfileFilePaths().config;
+      const configContent = fs.readFileSync(configPath, 'utf-8');
+      const configParsed = parseIni(configContent);
+      expect(configParsed['profile dev'].region).toBe('us-east-1');
+    });
+
+    it('resolves credentials and config paths independently from env vars', {}, () => {
+      process.env.AWS_SHARED_CREDENTIALS_FILE = '/custom-creds/credentials';
+      // AWS_CONFIG_FILE is NOT set — should use default path
+
+      fs.mkdirSync('/custom-creds', { recursive: true });
+
+      writeProfileFiles('dev', { AccessKeyId: 'AKIA', SecretAccessKey: 'secret' }, 'us-east-1', false);
+
+      expect(fs.existsSync('/custom-creds/credentials')).toBe(true);
+      // Config file should be at the default path (under homedir)
+      const defaultConfigPath = require('node:path').join(require('node:os').homedir(), '.aws', 'config');
+      expect(fs.existsSync(defaultConfigPath)).toBe(true);
+    });
+
+    it('produces AWS CLI-compatible INI output (golden file)', {}, () => {
+      writeProfileFiles(
+        'dev',
+        {
+          AccessKeyId: 'AKIAIOSFODNN7EXAMPLE',
+          SecretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
+          SessionToken: 'FwoGZXIvYXdzEBYaDEXAMPLE',
+        },
+        'us-east-1',
+        false,
+      );
+
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+
+      const configPath = getProfileFilePaths().config;
+      const configContent = fs.readFileSync(configPath, 'utf-8');
+
+      // Verify exact byte-for-byte format matching AWS CLI style:
+      // - [section] header on its own line
+      // - key = value with spaces around =
+      // - LF line endings, trailing newline
+      expect(credContent).toBe(
+        '[dev]\n' +
+          'aws_access_key_id = AKIAIOSFODNN7EXAMPLE\n' +
+          'aws_secret_access_key = wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY\n' +
+          'aws_session_token = FwoGZXIvYXdzEBYaDEXAMPLE\n',
+      );
+      expect(configContent).toBe('[profile dev]\n' + 'region = us-east-1\n');
+    });
+
+    it('golden file for multi-profile output', {}, () => {
+      writeProfileFiles('dev', { AccessKeyId: 'AKIADEV', SecretAccessKey: 'devSecret' }, 'us-east-1', false);
+      writeProfileFiles(
+        'prod',
+        { AccessKeyId: 'AKIAPROD', SecretAccessKey: 'prodSecret', SessionToken: 'prodToken' },
+        'us-west-2',
+        false,
+      );
+
+      const credsPath = getProfileFilePaths().credentials;
+      const credContent = fs.readFileSync(credsPath, 'utf-8');
+
+      const configPath = getProfileFilePaths().config;
+      const configContent = fs.readFileSync(configPath, 'utf-8');
+
+      expect(credContent).toBe(
+        '[dev]\n' +
+          'aws_access_key_id = AKIADEV\n' +
+          'aws_secret_access_key = devSecret\n' +
+          '\n' +
+          '[prod]\n' +
+          'aws_access_key_id = AKIAPROD\n' +
+          'aws_secret_access_key = prodSecret\n' +
+          'aws_session_token = prodToken\n',
+      );
+      expect(configContent).toBe(
+        '[profile dev]\n' + 'region = us-east-1\n' + '\n' + '[profile prod]\n' + 'region = us-west-2\n',
+      );
+    });
+  });
+
+  describe('symlink hardening', {}, () => {
+    const credsPath = '/home/user/.aws/credentials';
+    const configPath = '/home/user/.aws/config';
+
+    beforeEach(() => {
+      process.env.AWS_SHARED_CREDENTIALS_FILE = credsPath;
+      process.env.AWS_CONFIG_FILE = configPath;
+    });
+
+    it('mergeProfileSection refuses when the credentials path is a symlink and leaves the target unchanged', {}, () => {
+      fs.mkdirSync('/home/user/.aws', { recursive: true });
+      fs.mkdirSync('/etc', { recursive: true });
+      fs.writeFileSync('/etc/passwd', 'root:x:0:0::/root:/bin/sh');
+      fs.symlinkSync('/etc/passwd', credsPath);
+
+      expect(() => mergeProfileSection(credsPath, 'dev', { aws_access_key_id: 'AKIA' }, true)).toThrow(
+        /Refusing .* \(.* symbolic link\)/,
+      );
+      expect(fs.readFileSync('/etc/passwd', 'utf-8')).toBe('root:x:0:0::/root:/bin/sh');
+    });
+
+    it('mergeProfileSection refuses when the config path is a symlink', {}, () => {
+      fs.mkdirSync('/home/user/.aws', { recursive: true });
+      fs.mkdirSync('/etc', { recursive: true });
+      fs.writeFileSync('/etc/sensitive', 'do not overwrite');
+      fs.symlinkSync('/etc/sensitive', configPath);
+
+      expect(() => mergeProfileSection(configPath, 'profile dev', { region: 'us-east-1' }, true)).toThrow(
+        /Refusing .* \(.* symbolic link\)/,
+      );
+      expect(fs.readFileSync('/etc/sensitive', 'utf-8')).toBe('do not overwrite');
+    });
+
+    it('ensureAwsDirectoryExists refuses when ~/.aws is a symlink', {}, () => {
+      fs.mkdirSync('/real-target', { recursive: true });
+      fs.mkdirSync('/home/user', { recursive: true });
+      fs.symlinkSync('/real-target', '/home/user/.aws');
+
+      expect(() => ensureAwsDirectoryExists(credsPath)).toThrow(/Refusing .* \(.* symbolic link\)/);
+    });
+
+    it('writeProfileFiles refuses to overwrite a pre-existing symlink at the credentials path', {}, () => {
+      fs.mkdirSync('/home/user/.aws', { recursive: true });
+      fs.mkdirSync('/etc', { recursive: true });
+      fs.writeFileSync('/etc/passwd', 'root:x:0:0::/root:/bin/sh');
+      fs.symlinkSync('/etc/passwd', credsPath);
+
+      expect(() =>
+        writeProfileFiles('dev', { AccessKeyId: 'AKIA', SecretAccessKey: 'secret' }, 'us-east-1', true),
+      ).toThrow(/Refusing .* \(.* symbolic link\)/);
+
+      expect(fs.lstatSync(credsPath).isSymbolicLink()).toBe(true);
+      expect(fs.readFileSync('/etc/passwd', 'utf-8')).toBe('root:x:0:0::/root:/bin/sh');
+    });
+
+    it('happy path still writes both files with mode 0o600 when no symlinks are present', {}, () => {
+      writeProfileFiles('dev', { AccessKeyId: 'AKIA', SecretAccessKey: 'secret' }, 'us-east-1', false);
+
+      expect(fs.statSync(credsPath).mode & 0o777).toBe(0o600);
+      expect(fs.statSync(configPath).mode & 0o777).toBe(0o600);
+      expect(fs.lstatSync(credsPath).isSymbolicLink()).toBe(false);
+      expect(fs.lstatSync(configPath).isSymbolicLink()).toBe(false);
+    });
+  });
+});
@@ -3,7 +3,7 @@
    "allowUnreachableCode": false,
    "allowUnusedLabels": false,
    "strict": true,
-    "exactOptionalPropertyTypes": false,
+    "exactOptionalPropertyTypes": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitOverride": true,
    "noImplicitReturns": true,
@@ -23,7 +23,8 @@
    "target": "ES2020",
    "noErrorTruncation": true,
    "esModuleInterop": true,
-    "rootDir": "src"
+    "rootDir": "src",
+    "skipLibCheck": true
  },
  "include": ["src/**/*.ts"],
  "exclude": ["test/**/*.ts"]