diff --git a/README.md b/README.md
index 1d15799..a049ef4 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,33 @@ jobs:
 | `keystore-path`           | where the keystore should be placed      | No       | `release.keystore` |
 | `rock-build-extra-params` | Extra parameters for rock build:android  | No       | -                  |
 | `comment-bot`             | Whether to comment PR with build link    | No       | `true`             |
-| `custom-ref`              | Custom app reference for artifact naming | No       | -                  |
+| `custom-identifier`       | Custom identifier used in artifact naming for re-sign and ad-hoc flows to distinguish builds with the same native fingerprint     | No       | -           |
+
+## Artifact Naming
+
+The action uses two distinct naming strategies for uploads:
+
+### ZIP Artifacts (native build caching)
+
+ZIP artifacts store the native build for reuse. The naming depends on the flow:
+
+- **Ad-hoc flow** (`ad-hoc: true`): ZIP name uses **fingerprint only** — `rock-android-{variant}-{fingerprint}`. One ZIP per fingerprint, shared across all builds with the same native code. Skipped if already uploaded.
+- **Non-ad-hoc re-sign flow** (e.g. `pull_request` with `re-sign: true`): ZIP name includes an **identifier** — `rock-android-{variant}-{identifier}-{fingerprint}`. Used as the distribution mechanism without adhoc builds.
+- **Regular builds** (no `re-sign`): ZIP name uses **fingerprint only** `rock-android-{variant}-{fingerprint}`
+
+### Ad-Hoc Artifacts (distribution to testers)
+
+When `ad-hoc: true`, distribution files (APK + `index.html`) are uploaded under a name that **always includes an identifier**: `rock-android-{variant}-{identifier}-{fingerprint}`. This ensures every uploaded adhoc build can point to unique distribution URL based on `{identifier}`, even when multiple builds share the same native fingerprint.
+
+### Identifier Priority
+
+The identifier distinguishes builds that share the same native fingerprint (e.g., concurrent builds from different branches).
+It is resolved in this order:
+1. `custom-identifier` input — explicit value provided by the caller (e.g., commit SHA of the head of the PR branch)
+2. PR number — automatically extracted from `pull_request` events
+3. Short commit SHA — 7-character fallback for push events and dispatches
+
+> **Note:** The identifier becomes part of artifact names and S3 paths. Allowed characters: `a-z`, `A-Z`, `0-9`, `-`, `.`, `_`. Commas are used internally as trait delimiters and converted to hyphens (e.g., `debug,42` → `debug-42`), so they must not appear in the identifier. Spaces, slashes, and shell metacharacters are also not allowed.
 
 ## Outputs
 
diff --git a/action.yml b/action.yml
index dac4d0f..71a231e 100644
--- a/action.yml
+++ b/action.yml
@@ -68,8 +68,8 @@ inputs:
     description: 'Whether to send a comment under PR with the link to the generated build'
     required: false
     default: true
-  custom-ref:
-    description: 'Custom app reference for artifact naming'
+  custom-identifier:
+    description: 'Custom identifier used in artifact naming for re-sign and ad-hoc flows to distinguish builds with the same native fingerprint'
     required: false
 
 outputs:
@@ -290,16 +290,28 @@ runs:
       shell: bash
       working-directory: ${{ inputs.working-directory }}
 
-    - name: Update Artifact Name for re-signed builds
-      if: ${{ env.ARTIFACT_URL && inputs.re-sign == 'true' }}
+    - name: Set Identifier
+      if: ${{ inputs.re-sign == 'true' || inputs.ad-hoc == 'true' }}
       run: |
-        if [ "${{ github.event_name }}" = "pull_request" ]; then
+        if [ -n "${{ inputs.custom-identifier }}" ]; then
+          IDENTIFIER="${{ inputs.custom-identifier }}"
+          if ! echo "$IDENTIFIER" | grep -qE '^[a-zA-Z0-9._-]+$'; then
+            echo "Invalid 'custom-identifier': '$IDENTIFIER'. Use only alphanumeric characters, hyphens, dots, and underscores."
+            exit 1
+          fi
+        elif [ "${{ github.event_name }}" = "pull_request" ]; then
           IDENTIFIER="${{ github.event.pull_request.number }}"
-        elif [ -n "${{ inputs.custom-ref }}" ]; then
-          IDENTIFIER="${{ inputs.custom-ref }}"
         else
           IDENTIFIER=$(echo "$GITHUB_SHA" | cut -c1-7)
         fi
+        echo "IDENTIFIER=$IDENTIFIER" >> $GITHUB_ENV
+      shell: bash
+
+    # Non-ad-hoc re-sign flow: add identifier to ARTIFACT_NAME so the re-signed ZIP Artifact doesn't overwrite the base ZIP.
+    # Skipped for ad-hoc — ARTIFACT_NAME stays fingerprint-only (one ZIP Artifact per fingerprint).
+    - name: Update Artifact Name for re-signed builds
+      if: ${{ env.ARTIFACT_URL && inputs.re-sign == 'true' && inputs.ad-hoc != 'true' }}
+      run: |
         ARTIFACT_TRAITS="${{ inputs.variant }},${IDENTIFIER}"
         ARTIFACT_TRAITS_HYPHENATED=$(echo "$ARTIFACT_TRAITS" | tr ',' '-')
         ARTIFACT_TRAITS_HYPHENATED_FINGERPRINT="${ARTIFACT_TRAITS_HYPHENATED}-${FINGERPRINT}"
@@ -328,28 +340,45 @@ runs:
         path: ${{ env.ARTIFACT_PATH }}
         if-no-files-found: error
 
+    # Non-ad-hoc re-sign flow: upload ZIP Artifact with {identifier}-{fingerprint} name
     # For re-signed builds, the ARTIFACT_NAME may contain PR-number, while Rock will save the artifact without PR trait in its cache.
     # We need to upload the artifact with the PR-number in the name, that's why we use --binary-path with appropriate ARTIFACT_PATH that accounts for it.
-    - name: Upload Artifact to Remote Cache for re-signed builds
-      if: ${{ env.PROVIDER_NAME != 'GitHub' && inputs.re-sign == 'true' }}
+    - name: Upload re-signed ZIP Artifact for non-ad-hoc flow
+      if: ${{ env.PROVIDER_NAME != 'GitHub' && inputs.re-sign == 'true' && inputs.ad-hoc != 'true' }}
       run: |
         OUTPUT=$(npx rock remote-cache upload --name ${{ env.ARTIFACT_NAME }} --binary-path "${{ env.ARTIFACT_PATH }}" --json --verbose) || (echo "$OUTPUT" && exit 1)
         echo "ARTIFACT_URL=$(echo "$OUTPUT" | jq -r '.url')" >> $GITHUB_ENV
       shell: bash
 
-    - name: Upload Artifact to Remote Cache for regular builds
-      if: ${{ env.PROVIDER_NAME != 'GitHub' && inputs.re-sign != 'true' && !env.ARTIFACT_URL }}
+    # Upload ZIP Artifact with {fingerprint}-only name as base ZIP Artifact for caching only (first build only).
+    # Runs only when no cached artifact exists (!ARTIFACT_URL), meaning native build was done from scratch.
+    # Excludes non-ad-hoc re-sign, which uploads with identifier in the name.
+    # Applies to:
+    # - regular builds (no ad-hoc, no re-sign)
+    # - re-sign with ad-hoc
+    - name: Upload ZIP Artifact for caching
+      if: ${{ env.PROVIDER_NAME != 'GitHub' && !env.ARTIFACT_URL && (inputs.re-sign != 'true' || inputs.ad-hoc == 'true') }}
       run: |
         OUTPUT=$(npx rock remote-cache upload --name ${{ env.ARTIFACT_NAME }} --json --verbose) || (echo "$OUTPUT" && exit 1)
         echo "ARTIFACT_URL=$(echo "$OUTPUT" | jq -r '.url')" >> $GITHUB_ENV
       shell: bash
 
-    # For ad-hoc builds, the ARTIFACT_NAME may contain PR-number, while Rock will save the artifact without PR trait in its cache.
-    # We need to upload the artifact with the PR-number in the name, that's why we use --binary-path with appropriate ARTIFACT_PATH that accounts for it.
+
+    # Ad-hoc uploads always include an identifier in the name {identifier}-{fingerprint}
+    - name: Set Ad-Hoc Artifact Name
+      if: ${{ inputs.ad-hoc == 'true' }}
+      run: |
+        ADHOC_TRAITS="${{ inputs.variant }},${IDENTIFIER}"
+        ADHOC_TRAITS_HYPHENATED=$(echo "$ADHOC_TRAITS" | tr ',' '-')
+        echo "ADHOC_ARTIFACT_NAME=rock-android-${ADHOC_TRAITS_HYPHENATED}-${FINGERPRINT}" >> $GITHUB_ENV
+      shell: bash
+
+    # Uploads APK/AAB + index.html under ad-hoc/{ADHOC_ARTIFACT_NAME}/.
+    # The ARTIFACT_URL output points to index.html
     - name: Upload for Ad-hoc distribution
       if: ${{ env.PROVIDER_NAME != 'GitHub' && inputs.ad-hoc == 'true' }}
       run: |
-        OUTPUT=$(npx rock remote-cache upload --name ${{ env.ARTIFACT_NAME }} --binary-path "${{ env.ARTIFACT_PATH }}" --json --ad-hoc) || (echo "$OUTPUT" && exit 1)
+        OUTPUT=$(npx rock remote-cache upload --name ${{ env.ADHOC_ARTIFACT_NAME }} --binary-path "${{ env.ARTIFACT_PATH }}" --json --ad-hoc) || (echo "$OUTPUT" && exit 1)
         echo "ARTIFACT_URL=$(echo "$OUTPUT" | jq -r '.url')" >> $GITHUB_ENV
       shell: bash