diff --git a/.github/labeler.yml b/.github/labeler.yml
new file mode 100644
index 00000000000..5bebcb9924c
--- /dev/null
+++ b/.github/labeler.yml
@@ -0,0 +1,220 @@
+# File-based auto-labeling configuration
+# Works with actions/labeler@v5
+# This complements auto-tag.yml (title-based labeling) by detecting which files changed
+
+# =============================================================================
+# Environment Sub-Labels (trigger specific tests in test-linux-libs.yml)
+# =============================================================================
+"Environments/brax":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/brax.py']
+
+"Environments/dm_control":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/dm_control.py']
+
+"Environments/envpool":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/envpool.py']
+
+"Environments/gym":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/gym.py', 'torchrl/envs/libs/_gym_utils.py']
+
+"Environments/habitat":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/habitat.py']
+
+"Environments/isaaclab":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/isaac_lab.py', 'torchrl/envs/libs/isaacgym.py']
+
+"Environments/jumanji":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/jumanji.py']
+
+"Environments/meltingpot":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/meltingpot.py']
+
+"Environments/open_spiel":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/openspiel.py']
+
+"Environments/pettingzoo":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/pettingzoo.py']
+
+"Environments/procgen":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/procgen.py']
+
+"Environments/robohive":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/robohive.py']
+
+"Environments/smacv2":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/smacv2.py']
+
+"Environments/unity_mlagents":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/unity_mlagents.py']
+
+"Environments/vmas":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/libs/vmas.py']
+
+"Environments/chess":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/envs/custom/chess.py']
+
+# Parent Environments label (any env lib change)
+"Environments":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/envs/libs/**'
+      - 'test/test_libs.py'
+
+# =============================================================================
+# Data Sub-Labels (trigger specific tests in test-linux-libs.yml)
+# =============================================================================
+"Data/gendgrl":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/data/datasets/gen_dgrl.py']
+
+"Data/minari":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/data/datasets/minari_data.py']
+
+"Data/openx":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/data/datasets/openx.py']
+
+"Data/roboset":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/data/datasets/roboset.py']
+
+"Data/vd4rl":
+  - changed-files:
+    - any-glob-to-any-file: ['torchrl/data/datasets/vd4rl.py']
+
+# Parent Data label
+"Data":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/data/datasets/**'
+
+# =============================================================================
+# LLM (triggers test-linux-llm.yml)
+# =============================================================================
+"llm/":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/envs/llm/**'
+      - 'torchrl/objectives/llm/**'
+      - 'torchrl/data/llm/**'
+      - 'torchrl/weight_update/llm/**'
+      - 'torchrl/modules/llm/**'
+      - 'torchrl/collectors/llm/**'
+      - 'test/llm/**'
+
+# =============================================================================
+# Core Module Labels (informational, core tests always run)
+# =============================================================================
+"Collectors":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/collectors/**'
+      - 'test/test_collectors.py'
+
+"Objectives":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/objectives/**'
+      - 'test/test_objectives.py'
+
+"Modules":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/modules/**'
+      - 'test/test_modules.py'
+      - 'test/test_tensordictmodules.py'
+      - 'test/test_actors.py'
+
+"Transforms":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/envs/transforms/**'
+      - 'test/test_transforms.py'
+
+"Trainers":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/trainers/**'
+      - 'test/test_trainer.py'
+
+"Record":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/record/**'
+      - 'test/test_loggers.py'
+
+"WeightUpdate":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/weight_update/**'
+
+"ReplayBuffers":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/data/replay_buffers/**'
+      - 'test/test_rb.py'
+      - 'test/test_storage_map.py'
+
+"Services":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/services/**'
+      - 'test/services/**'
+
+"distributions":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'torchrl/modules/distributions/**'
+      - 'test/test_distributions.py'
+
+# =============================================================================
+# Documentation & CI
+# =============================================================================
+"Documentation":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'docs/**'
+      - '*.md'
+      - '*.rst'
+
+"CI":
+  - changed-files:
+    - any-glob-to-any-file:
+      - '.github/**'
+
+"sota-implementations/":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'sota-implementations/**'
+
+"tutorials/":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'tutorials/**'
+
+"Examples":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'examples/**'
+
+"Benchmarks":
+  - changed-files:
+    - any-glob-to-any-file:
+      - 'benchmarks/**'
diff --git a/.github/labels.yml b/.github/labels.yml
index 4feb216866d..81625977ad4 100644
--- a/.github/labels.yml
+++ b/.github/labels.yml
@@ -132,10 +132,22 @@
   description: "Triggers chess environment tests only"
   color: "0E8A16"
 
+- name: Environments/dm_control
+  description: "Triggers dm_control environment tests"
+  color: "0E8A16"
+
 - name: Environments/envpool
   description: "Triggers envpool environment tests only"
   color: "0E8A16"
 
+- name: Environments/gym
+  description: "Triggers gym environment tests only"
+  color: "0E8A16"
+
+- name: Environments/habitat
+  description: "Triggers habitat environment tests"
+  color: "0E8A16"
+
 - name: Environments/isaaclab
   description: "Triggers Isaac Lab environment tests only"
   color: "0E8A16"
@@ -164,6 +176,10 @@
   description: "Triggers robohive environment tests only"
   color: "0E8A16"
 
+- name: Environments/sklearn
+  description: "Triggers sklearn tests only"
+  color: "0E8A16"
+
 - name: Environments/smacv2
   description: "Triggers smacv2 environment tests only"
   color: "0E8A16"
@@ -230,3 +246,49 @@
 - name: benchmarks/upload
   description: "Upload results of the PR to benchmarks"
   color: "5319E7"
+
+# =============================================================================
+# TorchRL Module Component Labels
+# =============================================================================
+- name: Objectives
+  description: "Changes to torchrl/objectives/"
+  color: "1D76DB"
+
+- name: Modules
+  description: "Changes to torchrl/modules/"
+  color: "1D76DB"
+
+- name: Transforms
+  description: "Changes to torchrl/envs/transforms/"
+  color: "1D76DB"
+
+- name: Record
+  description: "Changes to torchrl/record/"
+  color: "1D76DB"
+
+- name: Trainers
+  description: "Changes to torchrl/trainers/"
+  color: "1D76DB"
+
+- name: WeightUpdate
+  description: "Changes to torchrl/weight_update/"
+  color: "1D76DB"
+
+- name: Services
+  description: "Changes to torchrl/services/"
+  color: "1D76DB"
+
+- name: ReplayBuffers
+  description: "Changes to torchrl/data/replay_buffers/"
+  color: "1D76DB"
+
+# =============================================================================
+# Other Useful Labels
+# =============================================================================
+- name: sota-implementations/
+  description: "Changes to sota-implementations/"
+  color: "5319E7"
+
+- name: tutorials/
+  description: "Changes to tutorials/"
+  color: "0075ca"
diff --git a/.github/workflows/auto-labeler.yml b/.github/workflows/auto-labeler.yml
new file mode 100644
index 00000000000..d38374e6f6d
--- /dev/null
+++ b/.github/workflows/auto-labeler.yml
@@ -0,0 +1,31 @@
+# Automatically add labels to PRs based on which files changed
+#
+# This complements auto-tag.yml (title-based labeling):
+# - auto-tag.yml: Labels based on PR title prefix ([BugFix], [Feature], etc.)
+# - auto-labeler.yml: Labels based on which files/directories changed
+#
+# Together they provide complete PR categorization:
+# - Title-based labels capture the INTENT (bug fix, feature, etc.)
+# - File-based labels capture the SCOPE (which components changed)
+#------------------------------------------------------------
+
+name: Auto Label PR (File-Based)
+
+on:
+  pull_request_target:
+    types: [opened, synchronize]
+
+jobs:
+  label:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+      contents: read
+    steps:
+      - name: Apply labels based on changed files
+        uses: actions/labeler@v5
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          # Don't remove labels that aren't in the config
+          # This preserves manually-added labels and title-based labels from auto-tag.yml
+          sync-labels: false
diff --git a/.github/workflows/auto-tag.yml b/.github/workflows/auto-tag.yml
index 087c234c786..87d6d17ddfe 100644
--- a/.github/workflows/auto-tag.yml
+++ b/.github/workflows/auto-tag.yml
@@ -1,23 +1,23 @@
 # Automatically add a label to PRs based on the [Label] prefix in the title
 #
 # Usage:
-#  - PR title must start with an EXACT [Label] prefix (case-sensitive)
+#  - PR title must start with a [Label] prefix in brackets
 #  - Example: "[BugFix] Fix memory leak" will add the "BugFix" label
 #  - Fails if no valid prefix is found
-#  - When title is edited, old auto-label is replaced with the new one
+#  - Labels are ONLY ADDED, never removed (preserves manual labels)
 #
-# Supported prefixes (CASE-SENSITIVE - must match exactly):
-#  - [BugFix] → BugFix
-#  - [Feature] → Feature
-#  - [Doc] → Documentation
-#  - [Refactor] → Refactoring
+# Supported prefixes (supports common variations):
+#  - [BugFix], [Bugfix] → BugFix
+#  - [Feature], [Features] → Feature
+#  - [Doc], [Docs], [Documentation] → Documentation
+#  - [Refactor], [Refactoring] → Refactoring
 #  - [CI] → CI
-#  - [Tests] → Tests
-#  - [Environments] → Environments
+#  - [Test], [Tests] → Tests
+#  - [Environment], [Environments] → Environments
 #  - [Data] → Data
-#  - [Performance] → Performance
-#  - [BC-Breaking] → bc breaking
-#  - [Deprecation] → Deprecation
+#  - [Performance], [Perf] → Performance
+#  - [BC-Breaking], [BCBreaking] → bc breaking
+#  - [Deprecation], [Deprecated] → Deprecation
 #------------------------------------------------------------
 
 name: PR Label
@@ -40,8 +40,6 @@ jobs:
           PR_TITLE: ${{ github.event.pull_request.title }}
           PR_NUMBER: ${{ github.event.pull_request.number }}
           REPO: ${{ github.repository }}
-          # Known auto-labels that this workflow manages (actual GitHub label names)
-          AUTO_LABELS: "BugFix Feature Documentation Refactoring CI Tests Environments Data Performance bc breaking Deprecation"
         run: |
           set -euo pipefail
 
@@ -63,17 +61,17 @@ jobs:
           |--------|---------------|---------|
           | `[BugFix]` | BugFix | `[BugFix] Fix memory leak in collector` |
           | `[Feature]` | Feature | `[Feature] Add new optimizer` |
-          | `[Doc]` | Documentation | `[Doc] Update installation guide` |
+          | `[Doc]` or `[Docs]` | Documentation | `[Doc] Update installation guide` |
           | `[Refactor]` | Refactoring | `[Refactor] Clean up module imports` |
           | `[CI]` | CI | `[CI] Fix workflow permissions` |
-          | `[Tests]` | Tests | `[Tests] Add unit tests for buffer` |
-          | `[Environments]` | Environments | `[Environments] Add Gymnasium support` |
+          | `[Test]` or `[Tests]` | Tests | `[Tests] Add unit tests for buffer` |
+          | `[Environment]` or `[Environments]` | Environments | `[Environments] Add Gymnasium support` |
           | `[Data]` | Data | `[Data] Fix replay buffer sampling` |
-          | `[Performance]` | Performance | `[Performance] Optimize tensor ops` |
+          | `[Performance]` or `[Perf]` | Performance | `[Performance] Optimize tensor ops` |
           | `[BC-Breaking]` | bc breaking | `[BC-Breaking] Remove deprecated API` |
           | `[Deprecation]` | Deprecation | `[Deprecation] Mark old function` |
 
-          **Note:** Prefixes are case-sensitive. Use `[BugFix]` not `[bugfix]` or `[Bugfix]`.
+          **Note:** Common variations like singular/plural are supported (e.g., `[Doc]` or `[Docs]`).
           COMMENT_EOF
             # Strip leading spaces from heredoc (YAML indentation artifact)
             sed -i 's/^          //' /tmp/pr_comment.md
@@ -96,62 +94,51 @@ jobs:
 
           echo "Extracted prefix: $PREFIX"
 
-          # Map EXACT prefixes to GitHub label names (case-sensitive)
+          # Map prefixes to GitHub label names (supports common variations)
           case "$PREFIX" in
-            BugFix)
+            BugFix|Bugfix|bugfix)
               LABEL="BugFix"
               ;;
-            Feature)
+            Feature|Features|feature|features)
               LABEL="Feature"
               ;;
-            Doc)
+            Doc|Docs|Documentation|doc|docs)
               LABEL="Documentation"
               ;;
-            Refactor)
+            Refactor|Refactoring|refactor|refactoring)
               LABEL="Refactoring"
               ;;
-            CI)
+            CI|ci)
               LABEL="CI"
               ;;
-            Tests)
+            Test|Tests|test|tests)
               LABEL="Tests"
               ;;
-            Environments)
+            Environment|Environments|environment|environments)
               LABEL="Environments"
               ;;
-            Data)
+            Data|data)
               LABEL="Data"
               ;;
-            Performance)
+            Performance|Perf|performance|perf)
               LABEL="Performance"
               ;;
-            BC-Breaking)
+            BC-Breaking|BCBreaking|bc-breaking)
               LABEL="bc breaking"
               ;;
-            Deprecation)
+            Deprecation|Deprecated|deprecation|deprecated)
               LABEL="Deprecation"
               ;;
             *)
-              echo "::error::Unknown or invalid prefix '[$PREFIX]'. Prefixes are case-sensitive."
-              post_help_comment "Unknown or invalid prefix \`[$PREFIX]\`. Prefixes are case-sensitive." "$PR_TITLE"
+              echo "::error::Unknown or invalid prefix '[$PREFIX]'."
+              post_help_comment "Unknown or invalid prefix \`[$PREFIX]\`." "$PR_TITLE"
               exit 1
               ;;
           esac
 
           echo "Mapped to label: $LABEL"
 
-          # Get current labels on the PR
-          CURRENT_LABELS=$(gh pr view "$PR_NUMBER" --repo "$REPO" --json labels --jq '.labels[].name' 2>/dev/null || echo "")
-
-          # Remove any existing auto-labels that don't match the new one
-          for existing in $CURRENT_LABELS; do
-            if [[ "$existing" != "$LABEL" && " $AUTO_LABELS " == *" $existing "* ]]; then
-              echo "Removing old auto-label: $existing"
-              gh pr edit "$PR_NUMBER" --repo "$REPO" --remove-label "$existing" 2>/dev/null || true
-            fi
-          done
-
-          # Add the label to the PR
+          # Add the label to the PR (never remove existing labels)
           gh pr edit "$PR_NUMBER" --repo "$REPO" --add-label "$LABEL"
 
           echo "Successfully added label '$LABEL' to PR #$PR_NUMBER"