diff --git a/.skills/mcc-version-adaptation/SKILL.md b/.skills/mcc-version-adaptation/SKILL.md
index 706399cb..c5cc59b4 100644
--- a/.skills/mcc-version-adaptation/SKILL.md
+++ b/.skills/mcc-version-adaptation/SKILL.md
@@ -12,11 +12,11 @@ Systematic workflow for updating Minecraft Console Client to support a new Minec
 - Decompiled server source for both the old and new MC versions in `$MCC_REPO/MinecraftOfficial/<version>-decompiled/`
 - If missing, decompile and download server.jar:
   ```bash
-  $MCC_REPO/tools/decompile.sh --version <ver>
+  $MCC_REPO/tools/decompile.sh --version <ver>-Vanilla
   ```
-  This auto-downloads `MinecraftDecompiler.jar` if needed, produces the decompiled source, and downloads `server.jar` into `$MCC_SERVERS/<ver>/`.
-- `tools/decompile.sh` depends on official mappings. For older versions where it refuses to decompile, fall back to a raw Java decompiler such as `cfr-decompiler` against `$MCC_SERVERS/<ver>/server.jar`. That fallback is good enough for packet inspection and registration order checks even when the output is obfuscated.
-- A test server of the target version in `$MCC_SERVERS/<version>/` (see `mcc-dev-workflow` skill)
+  This auto-downloads `MinecraftDecompiler.jar` if needed, produces the decompiled source under `$MCC_REPO/MinecraftOfficial/<mc-version>-decompiled/`, and downloads `server.jar` into `$MCC_SERVERS/<ver>-Vanilla/`.
+- `tools/decompile.sh` depends on official mappings. For older versions where it refuses to decompile, fall back to a raw Java decompiler such as `cfr-decompiler` against `$MCC_SERVERS/<ver>-Vanilla/server.jar`. That fallback is good enough for packet inspection and registration order checks even when the output is obfuscated.
+- A test server of the target version in `$MCC_SERVERS/<version>-Vanilla/` (see `mcc-dev-workflow` skill)
 
 ## Step 0: Generate Server Reports (CRITICAL since 1.21.9)
 
diff --git a/docs/guide/ai-assisted-development.md b/docs/guide/ai-assisted-development.md
index 4313d67c..fa94e552 100644
--- a/docs/guide/ai-assisted-development.md
+++ b/docs/guide/ai-assisted-development.md
@@ -335,12 +335,12 @@ git submodule update --init --recursive
 From the repo root, use the decompiler helper to download the official server jar and create the decompiled source tree:
 
 ```bash
-tools/decompile.sh --version 1.20.6
+tools/decompile.sh --version 1.20.6-Vanilla
 ```
 
 That creates the paths used by the harness and the version-adaptation workflow:
 
-- `$MCC_SERVERS/1.20.6/server.jar`
+- `$MCC_SERVERS/1.20.6-Vanilla/server.jar`
 - `MinecraftOfficial/1.20.6-decompiled/`
 
 If you are doing protocol work, this step is not optional.
@@ -544,13 +544,13 @@ This is the core loop you should expect an agent to follow.
 source tools/mcc-env.sh
 SESSION="smoke-a"
 USERNAME="$(_mcc_resolve_username "$SESSION")"
-mc-start 1.20.6
+mc-start 1.20.6-Vanilla
 ```
 
 Check the recent server output:
 
 ```bash
-mc-log 1.20.6
+mc-log 1.20.6-Vanilla
 ```
 
 ### 2. Build MCC
@@ -562,7 +562,7 @@ mcc-build
 ### 3. Run MCC with file input enabled
 
 ```bash
-mcc-debug -v 1.20.6 --file-input --session "$SESSION" --no-build
+mcc-debug -v 1.20.6-Vanilla --file-input --session "$SESSION" --no-build
 ```
 
 ### 4. Set up server state through RCON
@@ -665,7 +665,7 @@ The important rule is simple:
 
 The usual order is:
 
-1. `tools/decompile.sh --version <ver>`
+1. `tools/decompile.sh --version <ver>-Vanilla`
 2. generate server reports from `server.jar`
 3. run `tools/diff_registries.py`
 4. regenerate the palettes that actually changed
@@ -692,9 +692,9 @@ Typical loop:
 source tools/mcc-env.sh
 SESSION="smoke-a"
 USERNAME="$(_mcc_resolve_username "$SESSION")"
-mc-start 1.20.6
+mc-start 1.20.6-Vanilla
 mcc-build
-mcc-debug -v 1.20.6 --file-input --session "$SESSION" --no-build
+mcc-debug -v 1.20.6-Vanilla --file-input --session "$SESSION" --no-build
 mc-rcon "op $USERNAME"
 mcc-cmd --session "$SESSION" "inventory player list"
 mcc-cmd --session "$SESSION" "entity"
@@ -737,7 +737,7 @@ Use skills:
 Typical flow:
 
 ```bash
-tools/decompile.sh --version 26.1
+tools/decompile.sh --version 26.1-Vanilla
 ```
 
 Generate server reports:
diff --git a/tools/README.md b/tools/README.md
index 39c686d4..c7a13648 100644
--- a/tools/README.md
+++ b/tools/README.md
@@ -51,13 +51,15 @@ Two types of data can be used as input:
 ### Decompiling a new MC version
 
 ```bash
-# Server side (default) — also downloads server.jar into MinecraftOfficial/downloads/<ver>/
-tools/decompile.sh --version 1.21.9
+# Server side (default) — downloads server.jar into $MCC_SERVERS/<ver>-Vanilla/
+tools/decompile.sh --version 1.21.9-Vanilla
 
 # Client side
 tools/decompile.sh --version 1.21.9 --side CLIENT
 ```
 
+For server-side runs, the decompiled source still lands in `MinecraftOfficial/<mc-version>-decompiled/`, while the runnable local server directory becomes `$MCC_SERVERS/<mc-version>-Vanilla/`.
+
 If you keep server assets outside the repo, set `MCC_SERVERS=/path/to/servers` before using `tools/mcc-env.sh` or `tools/start-server.sh`.
 
 The script auto-downloads `MinecraftDecompiler.jar` from GitHub releases if it doesn't exist.
diff --git a/tools/decompile.sh b/tools/decompile.sh
index 791431ba..9f922b8c 100644
--- a/tools/decompile.sh
+++ b/tools/decompile.sh
@@ -6,13 +6,14 @@
 #   ./tools/decompile.sh --version <ver> [--side SERVER|CLIENT]
 #
 # Examples:
-#   ./tools/decompile.sh --version 1.21.11
+#   ./tools/decompile.sh --version 1.21.11-Vanilla
 #   ./tools/decompile.sh --version 1.21.11 --side CLIENT
 
 set -euo pipefail
 
 REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
 MC_OFFICIAL="$REPO_ROOT/MinecraftOfficial"
+SERVERS_ROOT="${MCC_SERVERS:-$MC_OFFICIAL/downloads}"
 DECOMPILER_JAR="$MC_OFFICIAL/MinecraftDecompiler.jar"
 DECOMPILER_REPO="MaxPixelStudios/MinecraftDecompiler"
 
@@ -27,7 +28,7 @@ while [[ $# -gt 0 ]]; do
             echo "Usage: $0 --version <ver> [--side SERVER|CLIENT]"
             echo ""
             echo "Options:"
-            echo "  --version <ver>     Minecraft version (e.g. 1.21.11)"
+            echo "  --version <ver>     Minecraft version or local server dir (e.g. 1.21.11 or 1.21.11-Vanilla)"
             echo "  --side <env>        SERVER (default) or CLIENT"
             exit 0
             ;;
@@ -46,6 +47,16 @@ if [[ "$SIDE" != "SERVER" && "$SIDE" != "CLIENT" ]]; then
     exit 1
 fi
 
+MC_VERSION="${VERSION%-Vanilla}"
+if [[ -z "$MC_VERSION" ]]; then
+    MC_VERSION="$VERSION"
+fi
+
+SERVER_DIR_NAME="$VERSION"
+if [[ "$SIDE" == "SERVER" && "$VERSION" != *-Vanilla ]]; then
+    SERVER_DIR_NAME="${MC_VERSION}-Vanilla"
+fi
+
 # --- Ensure MinecraftDecompiler.jar exists ---
 if [[ ! -f "$DECOMPILER_JAR" ]]; then
     echo "MinecraftDecompiler.jar not found, downloading latest release..."
@@ -71,11 +82,11 @@ fi
 SIDE_LOWER="$(echo "$SIDE" | tr '[:upper:]' '[:lower:]')"
 
 if [[ "$SIDE" == "SERVER" ]]; then
-    REMAPPED_JAR="$MC_OFFICIAL/remapped_jar/${VERSION}-remapped.jar"
-    DECOMPILED_DIR="$MC_OFFICIAL/${VERSION}-decompiled"
+    REMAPPED_JAR="$MC_OFFICIAL/remapped_jar/${MC_VERSION}-remapped.jar"
+    DECOMPILED_DIR="$MC_OFFICIAL/${MC_VERSION}-decompiled"
 else
-    REMAPPED_JAR="$MC_OFFICIAL/remapped_jar/${VERSION}-${SIDE_LOWER}-remapped.jar"
-    DECOMPILED_DIR="$MC_OFFICIAL/${VERSION}-${SIDE_LOWER}-decompiled"
+    REMAPPED_JAR="$MC_OFFICIAL/remapped_jar/${MC_VERSION}-${SIDE_LOWER}-remapped.jar"
+    DECOMPILED_DIR="$MC_OFFICIAL/${MC_VERSION}-${SIDE_LOWER}-decompiled"
 fi
 
 if [[ -d "$DECOMPILED_DIR" ]]; then
@@ -92,12 +103,12 @@ VERSION_URL=$(curl -sL "$MANIFEST_URL" | python3 -c "
 import json, sys
 data = json.load(sys.stdin)
 for v in data['versions']:
-    if v['id'] == '$VERSION':
+    if v['id'] == '$MC_VERSION':
         print(v['url'])
         break
 ")
 if [[ -z "$VERSION_URL" ]]; then
-    echo "Error: version $VERSION not found in Mojang launcher manifest."
+    echo "Error: version $MC_VERSION not found in Mojang launcher manifest."
     exit 1
 fi
 
@@ -109,9 +120,12 @@ data = json.load(sys.stdin)
 print('true' if '$MAPPING_KEY' in data.get('downloads', {}) else 'false')
 ")
 
-echo "=== Decompiling Minecraft $VERSION ($SIDE) ==="
+echo "=== Decompiling Minecraft $MC_VERSION ($SIDE) ==="
 echo "  Remapped JAR: $REMAPPED_JAR"
 echo "  Decompiled:   $DECOMPILED_DIR"
+if [[ "$SIDE" == "SERVER" ]]; then
+    echo "  Server dir:   $SERVERS_ROOT/$SERVER_DIR_NAME"
+fi
 echo "  Obfuscated:   $HAS_MAPPINGS"
 echo ""
 
@@ -120,7 +134,7 @@ cd "$MC_OFFICIAL"
 if [[ "$HAS_MAPPINGS" == "true" ]]; then
     # Obfuscated version: use --version/--side to auto-download jar + mappings + deobfuscate
     java -jar "$DECOMPILER_JAR" \
-        --version "$VERSION" \
+        --version "$MC_VERSION" \
         --side "$SIDE" \
         --decompile \
         --output "$REMAPPED_JAR" \
@@ -129,14 +143,14 @@ else
     # Unobfuscated version (26.1+): download jar, extract inner jar from bundle, decompile directly.
     # MinecraftDecompiler requires --mapping-path with --input, but unobfuscated versions
     # have no mappings. We use Vineflower directly instead.
-    echo "No Proguard mappings for $VERSION; decompiling without deobfuscation."
+    echo "No Proguard mappings for $MC_VERSION; decompiling without deobfuscation."
 
     JAR_URL=$(echo "$VERSION_META" | python3 -c "
 import json, sys
 data = json.load(sys.stdin)
 print(data['downloads']['${SIDE_LOWER}']['url'])
 ")
-    ORIGINAL_JAR="$MC_OFFICIAL/remapped_jar/${VERSION}-${SIDE_LOWER}-original.jar"
+    ORIGINAL_JAR="$MC_OFFICIAL/remapped_jar/${MC_VERSION}-${SIDE_LOWER}-original.jar"
     if [[ ! -f "$ORIGINAL_JAR" ]]; then
         echo "Downloading ${SIDE_LOWER}.jar ..."
         curl -L -o "$ORIGINAL_JAR" "$JAR_URL"
@@ -175,13 +189,13 @@ echo ""
 echo "=== Done ==="
 echo "Decompiled source: $DECOMPILED_DIR"
 
-# --- For SERVER side, also ensure downloads/<ver>/server.jar exists ---
+# --- For SERVER side, also ensure downloads/<server-dir>/server.jar exists ---
 if [[ "$SIDE" == "SERVER" ]]; then
-    DOWNLOADS_DIR="$MC_OFFICIAL/downloads/$VERSION"
+    DOWNLOADS_DIR="$SERVERS_ROOT/$SERVER_DIR_NAME"
     if [[ ! -f "$DOWNLOADS_DIR/server.jar" ]]; then
         mkdir -p "$DOWNLOADS_DIR"
         echo ""
-        echo "Downloading server.jar for $VERSION into $DOWNLOADS_DIR ..."
+        echo "Downloading server.jar for $MC_VERSION into $DOWNLOADS_DIR ..."
         SERVER_JAR_URL=$(echo "$VERSION_META" | python3 -c "
 import json, sys
 data = json.load(sys.stdin)