@@ -12,7 +12,7 @@ PROJECT_NAME="airstack"
 # If you've run ./airstack.sh setup, then this will auto-generate from the git commit hash every time a change is made 
 # to a Dockerfile or docker-compose.yaml file. Otherwise this can also be set explicitly to make a release version.
 # auto-generated from git commit hash
-VERSION="0.20.0-alpha.11"
+VERSION="0.20.0-alpha.12"
 # Image-tag discriminator ONLY (appears in the image tag suffix, e.g. ..._robot-x86-64_dev).
 # No Dockerfile consumes it: "prebuilt" does NOT bake the built ros_ws into the image today —
 # a real prebuilt (workspace-baked) stage is future work. Keep "dev" (mounted code, built live).
@@ -37,10 +37,19 @@ ISAAC_SIM_USE_STANDALONE="true" # "true" or "false"
 # Script name (must be in /AirStack/simulation/isaac-sim/launch_scripts/)
 ISAAC_SIM_SCRIPT_NAME="example_one_px4_pegasus_launch_script.py"
 PLAY_SIM_ON_START="false"  # Sim comes up PAUSED by default (press Play, or launch with `airstack up --play`). System tests force this to true.
+# Scene to load, set by `airstack up --scene <shortname>` (see simulation/scenes.yaml
+# for shortnames). Can also be set directly to a Pegasus SIMULATION_ENVIRONMENTS
+# key or a USD URL. Empty = the launch script's default (Default Environment).
+# ISAAC_SIM_SCENE="Warehouse"
+# ISAAC_SIM_STAGE_SCALE="1.0"  # scale applied to /World/stage (0.01 for cm-authored stages)
 
 # ===============================================
 
 # ================= MS-AIRSIM =====================
+# Scene to run, set by `airstack up --scene <shortname>` (see simulation/scenes.yaml).
+# A fetch_scene.sh key; the pre-built UE4 binary is auto-fetched if absent.
+# Empty = blocks. Ignored when MS_AIRSIM_BINARY_PATH is set.
+# MS_AIRSIM_SCENE="blocks"
 # Do not set if you want airstack to fetch a simple blocks world.
 # MS_AIRSIM_ENV_DIR=./simulation/ms-airsim/assets/scenes
 # MS_AIRSIM_BINARY_PATH="/ms-airsim-env/Blocks/LinuxNoEditor/Blocks.sh"
 
@@ -183,6 +183,12 @@ function print_command_help {
             echo "                      heterogeneous fleets) generates the per-robot services plus"
             echo "                      split-stack DDS-router configs. Mutually exclusive with"
             echo "                      --robots. See docs/development/fleets.md."
+            echo "  --scene NAME        Select the simulation scene by shortname (simulation/scenes.yaml):"
+            echo "                      maps NAME to the selected simulator's scene reference and"
+            echo "                      exports it (Isaac: ISAAC_SIM_SCENE [+ ISAAC_SIM_STAGE_SCALE] —"
+            echo "                      a Pegasus catalog key or Nucleus USD URL; MS AirSim:"
+            echo "                      MS_AIRSIM_SCENE — a pre-built UE4 scene, auto-fetched if"
+            echo "                      missing). Unknown scene = error + table of available scenes."
             echo "  --headless          Run the sim without a GUI (ISAAC_SIM_HEADLESS/MS_AIRSIM_HEADLESS)."
             echo "  --play / --no-play  Start the sim playing, or paused (PLAY_SIM_ON_START)."
             echo "  --no-autolaunch     Start containers idle (AUTOLAUNCH=false; launch manually)."
@@ -1126,6 +1132,7 @@ function parse_launch_intent {
     AIRSTACK_INTENT_AUTOLAUNCH=""
     AIRSTACK_INTENT_STACK=""
     AIRSTACK_INTENT_FLEET=""
+    AIRSTACK_INTENT_SCENE=""
     AIRSTACK_FLEET_COMPOSE_FILE=""
     AIRSTACK_DRY_RUN=""
     AIRSTACK_UP_WAIT=""
@@ -1146,6 +1153,8 @@ function parse_launch_intent {
             --stack=*)      AIRSTACK_INTENT_STACK="${a#--stack=}";;
             --fleet)        i=$((i+1)); AIRSTACK_INTENT_FLEET="${args[$i]:-}";;
             --fleet=*)      AIRSTACK_INTENT_FLEET="${a#--fleet=}";;
+            --scene)        i=$((i+1)); AIRSTACK_INTENT_SCENE="${args[$i]:-}";;
+            --scene=*)      AIRSTACK_INTENT_SCENE="${a#--scene=}";;
             --wait)         AIRSTACK_UP_WAIT="1";;
             # NOTE: shadows compose's own `up --dry-run`; ours validates the
             # derived launch config and exits without starting services.
@@ -1413,6 +1422,77 @@ function apply_launch_intent {
             export ISAAC_SIM_SCRIPT_NAME="$want"
         fi
     fi
+
+    # --scene: map the shortname to the ACTIVE simulator's scene reference via
+    # simulation/scenes.yaml and export it (leaf values only). Unknown scene or
+    # wrong simulator = the resolver prints the availability table and we fail.
+    if [[ -n "$AIRSTACK_INTENT_SCENE" ]]; then
+        local scene_sim=""
+        [[ ",$profiles_final," == *",isaac-sim,"* ]] && scene_sim="isaac"
+        [[ ",$profiles_final," == *",ms-airsim,"* ]] && scene_sim="msairsim"
+        if [[ -z "$scene_sim" ]]; then
+            log_error "--scene requires an Isaac or MS AirSim profile (resolved profiles: ${profiles_final:-<none>}); simple-sim has no scene catalog. Use 'airstack up --sim isaac|airsim --scene $AIRSTACK_INTENT_SCENE'."
+            python3 "$PROJECT_ROOT/simulation/resolve_scene.py" --table >&2 || true
+            return 1
+        fi
+        local scene_exports line
+        if ! scene_exports=$(python3 "$PROJECT_ROOT/simulation/resolve_scene.py" \
+                --sim "$scene_sim" --scene "$AIRSTACK_INTENT_SCENE"); then
+            return 1  # resolver already printed the error + table on stderr
+        fi
+        while IFS= read -r line; do
+            [[ -z "$line" ]] && continue
+            export "${line?}"
+            log_info "--scene $AIRSTACK_INTENT_SCENE → $line"
+        done <<< "$scene_exports"
+        if [[ "$scene_sim" == "msairsim" ]]; then
+            ensure_msairsim_scene "$(resolve_launch_var MS_AIRSIM_SCENE "$@")" "$@" || return 1
+        fi
+    fi
+    return 0
+}
+
+# MS AirSim scenes are pre-built UE4 binaries fetched into the (bind-mounted)
+# scenes dir on first use. When --scene selects one that is not present
+# locally, offer to download it now (interactive) so the multi-GB fetch
+# doesn't silently happen inside the container; non-interactive runs keep the
+# in-container auto-fetch (visible in the airsim tmux window).
+function ensure_msairsim_scene {
+    local scene_key="$1"; shift
+    local fetch_sh="$PROJECT_ROOT/simulation/ms-airsim/assets/scenes/fetch_scene.sh"
+
+    # An explicit binary path bypasses the catalog entirely.
+    local bin
+    bin=$(resolve_launch_var MS_AIRSIM_BINARY_PATH "$@")
+    if [[ -n "$bin" ]]; then
+        log_warn "--scene is overridden by MS_AIRSIM_BINARY_PATH=$bin (the explicit binary path wins in the container). Unset MS_AIRSIM_BINARY_PATH to use --scene."
+        return 0
+    fi
+
+    local env_dir name
+    env_dir=$(resolve_launch_var MS_AIRSIM_ENV_DIR "$@")
+    [[ -z "$env_dir" ]] && env_dir="$PROJECT_ROOT/simulation/ms-airsim/assets/scenes"
+    [[ "$env_dir" != /* ]] && env_dir="$PROJECT_ROOT/${env_dir#./}"
+    name=$(bash "$fetch_sh" --name "$scene_key") || {
+        log_error "fetch_scene.sh does not know scene key '$scene_key' (simulation/scenes.yaml out of sync?)"
+        return 1
+    }
+    if compgen -G "$env_dir/$name/LinuxNoEditor/*.sh" > /dev/null; then
+        return 0
+    fi
+    log_warn "MS AirSim scene '$name' is not present locally under $env_dir."
+    if [[ -t 0 && -t 1 && "${AIRSTACK_ASSUME_YES:-}" != "1" ]]; then
+        local ans
+        read -r -p "Download it now from github.com/microsoft/AirSim v1.8.1 (can be several GB)? [Y/n] " ans
+        case "$ans" in
+            n|N|no|NO)
+                log_error "Aborted. Point MS_AIRSIM_BINARY_PATH at an existing scene binary, or rerun and accept the download."
+                return 1;;
+        esac
+        SCENES_DIR="$env_dir" bash "$fetch_sh" "$scene_key" || return 1
+    else
+        log_info "Non-interactive run: the airsim container will auto-fetch '$name' on first launch (progress in the airsim tmux window)."
+    fi
     return 0
 }
 
@@ -1428,6 +1508,11 @@ function print_launch_config {
     local _fleet_cfg
     _fleet_cfg=$(resolve_launch_var FLEET_CONFIG_FILE "$@")
     [[ -n "$_fleet_cfg" ]] && keys+=(FLEET_CONFIG_FILE)
+    # Scene keys likewise only appear when a scene is selected (--scene or env).
+    local _sk
+    for _sk in ISAAC_SIM_SCENE ISAAC_SIM_STAGE_SCALE MS_AIRSIM_SCENE; do
+        [[ -n "$(resolve_launch_var "$_sk" "$@")" ]] && keys+=("$_sk")
+    done
     local k v lines=()
     for k in "${keys[@]}"; do
         v=$(resolve_launch_var "$k" "$@")
@@ -1438,7 +1523,14 @@ function print_launch_config {
     profiles=$(resolve_launch_var COMPOSE_PROFILES "$@")
     log_info "Launch config: profiles=$profiles robots=$(resolve_launch_var NUM_ROBOTS "$@") autolaunch=$(resolve_launch_var AUTOLAUNCH "$@") play_on_start=$(resolve_launch_var PLAY_SIM_ON_START "$@")"
     if [[ ",$profiles," == *",isaac-sim,"* ]]; then
-        log_info "  isaac: script=$(resolve_launch_var ISAAC_SIM_SCRIPT_NAME "$@") headless=$(resolve_launch_var ISAAC_SIM_HEADLESS "$@")"
+        local _isaac_scene
+        _isaac_scene=$(resolve_launch_var ISAAC_SIM_SCENE "$@")
+        log_info "  isaac: script=$(resolve_launch_var ISAAC_SIM_SCRIPT_NAME "$@") headless=$(resolve_launch_var ISAAC_SIM_HEADLESS "$@")${_isaac_scene:+ scene=$_isaac_scene}"
+    fi
+    if [[ ",$profiles," == *",ms-airsim,"* ]]; then
+        local _airsim_scene
+        _airsim_scene=$(resolve_launch_var MS_AIRSIM_SCENE "$@")
+        [[ -n "$_airsim_scene" ]] && log_info "  ms-airsim: scene=$_airsim_scene"
     fi
     log_info "  urdf=$(resolve_launch_var URDF_FILE "$@")"
     local _stack_dir
 
@@ -128,6 +128,28 @@ Feature docs deliberately cite none of these — the design sources live here:
   `--dry-run` — deriving the coordinated env-var sets as exported leaf
   values, with a resolved-config banner and a per-run
   `.airstack/runs/<ts>/effective_config.env` dump; contract-tested
+- `airstack up --scene <shortname>`: simulator-agnostic scene selection via
+  a new catalog (`simulation/scenes.yaml`, resolved host-side by
+  `simulation/resolve_scene.py`). Isaac maps shortnames to Pegasus catalog
+  keys or Nucleus USD URLs (exported as `ISAAC_SIM_SCENE` +
+  `ISAAC_SIM_STAGE_SCALE`; the example launch scripts and `fleet_spawn.py`
+  now resolve their scene from these instead of hardcoding `env_url`);
+  MS AirSim maps to `fetch_scene.sh` keys (`MS_AIRSIM_SCENE` — the
+  entrypoint's auto-fetch, previously Blocks-only, now fetches any catalog
+  scene, and an interactive `airstack up` asks before a multi-GB download).
+  The `fetch_scene.sh` catalog was corrected to the UE4 binaries that
+  actually exist in the AirSim v1.8.1 release: `forest`, `soccerfield`, and
+  `building99` were removed (their zips were never published, or are empty),
+  `airsimnh` now downloads `AirSimNH.zip` (was the nonexistent
+  `Neighborhood.zip`), and `africasavannah` / `msbuild2018` were added; the
+  entrypoint resolves the UE launcher by glob after extraction, so zips whose
+  inner `.sh` doesn't match the folder name still boot.
+  Unknown scene = error + per-simulator availability table. Five stages were
+  published to the guest-readable
+  `omniverse://airlab-nucleus.andrew.cmu.edu:443/Public/AirStack/Stages/`
+  (AbandonedFactory, AbandonedWarehouse day/night, ChemicalPlant,
+  ConstructionSite, RetroNeighborhood) and cataloged with per-stage scale.
+  See [Simulation Scenes](../simulation/scenes.md)
 - `airstack ready` (and `airstack up --wait`): staged flight-readiness gates
   mirroring the system-test budgets — containers → sim `/clock` → per-robot
   sentinel nodes → PX4 MAVROS-connected + `local_position/odom` streaming —
 
@@ -43,7 +43,7 @@ Simulation components are launched via Docker Compose. Each simulator has its ow
 
 - **Launch command:** `airstack up --sim isaac` (or `airstack up isaac-sim` to start only the sim service)
 - **Main process:** The `command:` in docker-compose.yaml starts the simulator
-- **Scene selection (Isaac Sim):** the standalone launch script named by `ISAAC_SIM_SCRIPT_NAME` (in `.env`) defines the scene and drones; with `ISAAC_SIM_USE_STANDALONE=false`, `ISAAC_SIM_GUI` points at a USD file to open instead
+- **Scene selection:** `airstack up --scene <shortname>` picks the environment for whichever simulator is active — see [Simulation Scenes](scenes.md). The standalone launch script named by `ISAAC_SIM_SCRIPT_NAME` (in `.env`) defines the drones and honors the selected scene; with `ISAAC_SIM_USE_STANDALONE=false`, `ISAAC_SIM_GUI` points at a USD file to open instead
 - **Auto-play:** Controlled by `PLAY_SIM_ON_START` (or `airstack up --play`)
 
 **Example:**