Use sibling Baseline for upstream references

.gitignore

@@ -41,7 +41,7 @@ Thumbs.db
 # AI session transcripts (accidental commits)
 session-*.md
 
-# Local-only reference material (original NAAP Rotating Sky lab) — not part of the sim
+# Local decompile output (and any accidental NAAP re-clones). Upstream sources: ../Baseline/Astronomy/
 NAAP/
 
 # Flash decompilation tooling (npm run decompile) — downloaded FFDec

CLAUDE.md

@@ -80,6 +80,6 @@ npm run lint && npm run check && npm run build && npm test
 
 ## Development notes
 
-- **`npm run decompile`** extracts NAAP Flash ActionScript via JPEXS FFDec into gitignored `NAAP/decompiled/` — read-only reference.
+- **`npm run decompile`** extracts NAAP Flash ActionScript via JPEXS FFDec from `../Baseline/Astronomy/flash-animations` into gitignored `NAAP/decompiled/`.
 - To share state across screens instead, construct one `SkyModel` once and thread it through each per-screen model — see [doc/multi-screen.md](doc/multi-screen.md).
 - After `npm run build`, the sim is installable offline via Workbox (`dist/manifest.webmanifest`).

README.md

@@ -20,6 +20,21 @@ Vite 8, TypeScript 7, and Biome 2.
 
 See `doc/multi-screen.md` for the multi-screen architecture and how to share state across screens.
 
+### NAAP reference sources
+
+Upstream Flash / AIR / React NAAP sources live in the sibling
+[`Baseline`](https://github.com/OpenPhysics/Baseline) repo under `Astronomy/`
+(see `baselines.json`). Clone Baseline with the fleet bootstrap, then:
+
+```bash
+(cd ../Baseline && ./scripts/fetch-baselines.sh)
+```
+
+`npm run decompile` reads `.swf` files from
+`../Baseline/Astronomy/flash-animations` and writes ActionScript into the
+sim-local gitignored `NAAP/decompiled/` (requires Java; one-time
+`npm run decompile -- --setup`).
+
 ## Quick Start
 
 ```bash

scripts/decompile-flash.ts

@@ -2,7 +2,7 @@
  * decompile-flash.ts
  *
  * Extract readable ActionScript (and optionally assets) from the original NAAP
- * Flash sources under `NAAP/`, so the ported Rotating Sky sim can be checked
+ * Flash sources under `../Baseline/Astronomy/flash-animations/` (sibling Baseline repo), so the ported Rotating Sky sim can be checked
  * against the real implementation.
  *
  * The `.fla` files are old binary (OLE compound) projects that no current tool
@@ -35,7 +35,18 @@ import { inflateRawSync } from "node:zlib";
 
 const here = dirname(fileURLToPath(import.meta.url));
 const repoRoot = resolve(here, "..");
-const flashRoot = join(repoRoot, "NAAP", "flash-animations", "flashdev2");
+const flashRoot = resolve(repoRoot, "..", "Baseline", "Astronomy", "flash-animations", "flashdev2");
+
+/** Fail fast when the Baseline sibling checkout (or fetch) is missing. */
+function ensureFlashRoot(): void {
+  if (!existsSync(flashRoot)) {
+    fail(
+      `NAAP Flash sources not found at:\n  ${flashRoot}\n` +
+        `Clone OpenPhysics/Baseline as a sibling of this sim, then:\n` +
+        `  (cd ../Baseline && ./scripts/fetch-baselines.sh --only Astronomy/flash-animations)`,
+    );
+  }
+}
 
 /**
  * Latest canonical SWFs whose ActionScript informs the port (used by --all).
@@ -438,6 +449,8 @@ async function main(): Promise<void> {
     return;
   }
 
+  ensureFlashRoot();
+
   const movies = resolveTargets(opts);
   if (movies.length === 0) {
     fail("No .swf targets resolved. Check the paths, or run with --help.");