feat(dev): a run from source is its own app — levelcode-dev:// and its own bundle id

CLAUDE.md

@@ -40,7 +40,7 @@ extensions/levelcode-hackability/ user init script + Atom/NPP keymap presets + p
 extensions/levelcode-sync/       'levelcode' auth provider that lights up the built-in Settings Sync (LevelCode Sync, S0)
 extensions/levelcode-updater/    notify-only update checker (polls the update feed; never auto-applies)
 patches/levelcode-core.patch     our core source edits, applied on bootstrap
-scripts/                    bootstrap.sh, apply-branding.mjs, run-dev.sh, build-macos.sh, make-dmg.sh, make-icon.sh; atom (CLI launcher) + install-level.sh
+scripts/                    bootstrap.sh, apply-branding.mjs, run-dev.sh, editor-identity.mjs, build-macos.sh, make-dmg.sh, make-icon.sh; atom (CLI launcher) + install-level.sh
 tools/                      dependency-free reference servers: sync-server (/v1 Settings-Sync), update-server (/api/update feed)
 vscode/                     GITIGNORED upstream Code-OSS checkout (generated)
 ```
@@ -55,6 +55,33 @@ vscode/                     GITIGNORED upstream Code-OSS checkout (generated)
 ./scripts/make-icon.sh        # regenerate .icns from branding/icons/levelcode-source.png (sips+iconutil)
 ```
 
+## The dev editor is its own app (keep it that way)
+
+To macOS a run from source and the installed LevelCode used to be ONE app — same bundle id, same
+`levelcode://` scheme — so a sign-in started in the dev editor was handed back to the app in
+/Applications. `run-dev.sh` now gives the dev run its own identity (`scripts/editor-identity.mjs dev`):
+
+- **Identity:** `branding/product.dev.json` — scheme `levelcode-dev`, bundle id `ai.levelcode.app.dev`.
+  Both must differ from the shipped ones; a scheme alone still lets macOS confuse the two apps.
+- **Two halves, both required.** Runtime: `vscode/product.overrides.json` (Code-OSS reads it only when
+  running from source, never packages it). macOS: the dev Electron bundle's `Info.plist`, then
+  `lsregister`. The bundle is regenerated when Electron changes, so the step runs on every launch.
+- **Both or neither, and confirmed.** The two files are replaced as one change (staged, renamed, undone
+  if the second rename fails). Then the step asks macOS which app opens `levelcode-dev://` and FAILS —
+  `run-dev.sh` stops before launching — unless the answer is this bundle. `lsregister` exiting 0 is
+  not that answer: it registers a bundle it will never route to.
+- **`branding/product.overlay.json` is the product that ships — never put a dev value in it.**
+  `build-macos.sh` runs `editor-identity.mjs check-release` and fails a build that is not
+  `levelcode://` + `ai.levelcode.app`, or that carries an overrides file.
+- **Auth code never spells a scheme.** `accountSignIn()` builds the callback from
+  `vscode.env.uriScheme`; that is why the dev identity needed no auth change. Keep it so.
+- **The server must be told:** `LEVELCODE_EXTRA_EDITOR_SCHEMES=levelcode-dev` on the backend the dev
+  editor signs in to (thin.ly `Levelcode::EditorCallback`). Off by default, and it only ever accepts
+  `levelcode-<variant>`. Symptom when missing: the browser lands on the account page and the editor
+  hears nothing.
+- A LaunchServices handler must live outside temp folders — a bundle under `/tmp` is registered but
+  never chosen. Tests therefore run on fixtures and do not register anything (`test/editorIdentity.test.js`).
+
 ## Toolchain (hard requirements — these bit us)
 
 - **Node = `vscode/.nvmrc` (currently 24.15.0)**. Older majors fail to compile native modules.

README.md

@@ -49,6 +49,8 @@ LevelCode is a **clean overlay on top of Code-OSS**, not a vendored copy of the
 ./scripts/make-dmg.sh         # wrap it into a distributable .dmg
 ```
 
+**A run from source is its own app.** `run-dev.sh` gives the dev editor its own macOS identity — bundle id `ai.levelcode.app.dev` and the `levelcode-dev://` scheme (`branding/product.dev.json`) — so it can sit beside an installed LevelCode without the two answering each other's links. Signing in from it needs a server that accepts that scheme: set `LEVELCODE_EXTRA_EDITOR_SCHEMES=levelcode-dev` on the backend it signs in to. No server accepts it otherwise, and a sign-in that ends on the account page in the browser, with the editor hearing nothing, is the sign that it is not set.
+
 See [`CLAUDE.md`](./CLAUDE.md) for the full repo map + build details and [`PLAN.md`](./PLAN.md) for the roadmap.
 
 ## Status

branding/product.dev.json

@@ -0,0 +1,6 @@
+{
+	"_comment": "The identity of LevelCode RUN FROM SOURCE (scripts/run-dev.sh) — never of a build. To macOS the dev editor and the installed app were one app: same bundle id, same levelcode:// scheme, so a sign-in started in the dev editor was handed back to the app in /Applications. scripts/editor-identity.mjs gives the dev run these two values instead: at runtime through vscode/product.overrides.json (read only when running from source), and on the dev Electron bundle's Info.plist. branding/product.overlay.json — the product that ships — is not touched by any of it. The scheme must be levelcode-<variant>: that is the only shape a server can be told to accept (LEVELCODE_EXTRA_EDITOR_SCHEMES, thin.ly).",
+
+	"urlProtocol": "levelcode-dev",
+	"darwinBundleIdentifier": "ai.levelcode.app.dev"
+}