diff --git a/.gitignore b/.gitignore
index 5434925..83a2896 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,7 @@ CREDENTIALS.md
.aider*
ffmpeg/
BuildCounter.txt
+
+# Steamworks runtime (steam_api64.dll, 312 KB) — extracted from the SDK zip, never committed;
+# scripts/steam-sdk.sh documents which file and why. Same rule as ffmpeg/: the pin is the audit trail.
+steam/
diff --git a/Distribution.md b/Distribution.md
index ed4d48d..2430da5 100644
--- a/Distribution.md
+++ b/Distribution.md
@@ -46,9 +46,12 @@ dotnet publish ytLive.csproj -c Release -r win-x64 --self-contained true \
the DLC app ID is what the app passes to `BIsDlcInstalled`.
3. **Depot.** One depot holding the publish output; the base app and the DLC share the install
directory, and the DLC package grants no files of its own — it is entitlement only.
-4. **Steamworks SDK.** Drop `steam_api64.dll` (+ `steam_appid.txt` for local runs) into the publish
- output; the managed side is a thin wrapper (`Steamworks.NET` or hand-written interop) behind
- `IEntitlement`.
+4. **Steamworks SDK.** `./scripts/steam-sdk.sh ~/Downloads/steamworks_sdk_165.zip` extracts
+ `steam_api64.dll` from `sdk/redistributable_bin/win64/` into `steam/` (gitignored) and stages
+ `steam_appid.txt` = 480 — Valve's Spacewar app, so `SteamAPI.Init()` works locally before
+ LlamaCasty has an App ID. The csproj copies the DLL **beside the exe** (`Link`) with
+ `ExcludeFromSingleFile`, and copies `steam_appid.txt` in Debug only — never into a depot. The
+ managed side is the `Steamworks.NET` package (`SteamApps.BIsDlcInstalled`).
5. **Store page** configured and made public **two weeks before release** — Valve's rule, and it is
the window where wishlists accumulate.
diff --git a/TASKS.md b/TASKS.md
index 1afaa52..c582933 100644
--- a/TASKS.md
+++ b/TASKS.md
@@ -42,6 +42,7 @@ Dog test.
| 34 | ☐ | Scheduled streams (Text-drawer version) | [`task-34`](TASKS/task-34-scheduled-streams.md) |
| 35 | ☐ | Scene-linked audio | [`task-35`](TASKS/task-35-scene-linked-audio.md) |
| 37 | ☐ | Defaults vs current layout split (build-id); enables one-click revert to defaults | [`task-37`](TASKS/task-37-defaults-current-split.md) |
+| — | ☐ | **Preview undo (Ctrl+Z / Ctrl+Shift+Z)** — in edit mode, revert the last preview change (drag, resize, add, remove, property edit); bounded stack, cleared on scene change or layout load. The natural partner to 37: undo covers the slip, defaults cover the mess | this line |
| 39·2 | ☐ | YPP slice 2: Analytics scopes, watch-hours/Shorts velocity + ETA | [`task-39`](TASKS/task-39-ypp-journey-tracker.md) |
| 49 | ☐ | Chat profanity filter: local, opt-in, **non-persistent**, user-supplied word list | [`task-49`](TASKS/task-49-chat-profanity-filter.md) |
| 50 | ☐ | One-button publish of the local recording (resumable upload) | [`task-50`](TASKS/task-50-publish-recording.md) |
diff --git a/scripts/steam-sdk.sh b/scripts/steam-sdk.sh
new file mode 100644
index 0000000..3a109a0
--- /dev/null
+++ b/scripts/steam-sdk.sh
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+# steam-sdk.sh — extract the one file the app needs from the Steamworks SDK, and stage the
+# local-only app id.
+#
+# Why not unzip the whole SDK: it is ~24 MB of C++ headers, examples and tools we never build.
+# The runtime dependency is exactly one native library, and the release tooling (ContentBuilder)
+# is only needed on the machine that uploads a depot.
+#
+# ./scripts/steam-sdk.sh ~/Downloads/steamworks_sdk_165.zip
+#
+# steam_api64.dll is Valve's redistributable — shipping it beside a Steam-published exe is
+# permitted by the Steamworks terms. It is NOT committed: steam/ is gitignored, like ffmpeg/.
+
+set -euo pipefail
+
+ZIP="${1:-$HOME/Downloads/steamworks_sdk_165.zip}"
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+
+[ -f "$ZIP" ] || { echo "❌ SDK zip not found: $ZIP" >&2; echo " Download it from partner.steamgames.com/downloads/steamworks_sdk.zip while signed in." >&2; exit 1; }
+
+mkdir -p "$ROOT/steam"
+
+python3 - "$ZIP" "$ROOT" <<'PY'
+import sys, zipfile, pathlib
+
+zip_path, root = sys.argv[1], pathlib.Path(sys.argv[2])
+want = "sdk/redistributable_bin/win64/steam_api64.dll"
+dest = root / "steam" / "steam_api64.dll"
+
+with zipfile.ZipFile(zip_path) as z:
+ with z.open(want) as src, open(dest, "wb") as out:
+ out.write(src.read())
+
+print(f"✓ {dest.relative_to(root)} ({dest.stat().st_size // 1024} KB)")
+PY
+
+# steam_appid.txt is a LOCAL TESTING affordance: it lets SteamAPI.Init() resolve an app id
+# without going through the Steam client. 480 is Valve's public Spacewar test app, so the app
+# can be exercised before LlamaCasty has an app id of its own. It is Debug-only in the csproj
+# and must never ship in a depot — Valve's guidance is to remove it from release builds.
+printf '480\n' > "$ROOT/steam/steam_appid.txt"
+echo "✓ steam/steam_appid.txt = 480 (Spacewar, local Debug testing only)"
+
+echo ""
+echo "Next: the entitlement seam (IEntitlement + SteamApps.BIsDlcInstalled)."
diff --git a/ytLive.csproj b/ytLive.csproj
index e2069ad..266426b 100644
--- a/ytLive.csproj
+++ b/ytLive.csproj
@@ -100,6 +100,21 @@
+
+
+
+
+
+
+
+