release: produce a versioned per-browser artifact and pin the Chrome extension id (closes #310)

manifest/chrome.json now carries a fixed public key, so the extension id and the chrome.storage.local partition holding the wallet stay stable across checkout moves and re-clones instead of being derived from the absolute path. A release entrypoint produces a self-contained versioned artifact per browser, including the files that sit at dist/ root outside both browser directories. One version source of truth, enforced: the build fails naming the culprit when the two manifests and package.json disagree, and BUILD_COMMIT now marks a dirty tree as dirty. Firefox ships an unsigned XPI; the README states that release Firefox and ESR refuse it, that Developer Edition or Unbranded is required, and that Remove is irreversible except from the recovery phrase, which is asserted by test.

tests/extensionId.test.js

@@ -0,0 +1,119 @@
+// The extension identity on both browsers, pinned.
+//
+// This is the anti-regression check for
+// https://git.eeqj.de/sneak/AutistMask/issues/310. An unpacked Chrome
+// extension with no `key` in its manifest gets an id derived from the
+// ABSOLUTE PATH it was loaded from, and chrome.storage.local is partitioned by
+// that id. Move the checkout, re-clone it, or load it from a second directory,
+// and the wallet is silently gone: the extension comes up on a fresh, empty
+// storage partition with no error anywhere. `key` pins the id to the public
+// key instead of to the path, which is what makes the storage survive.
+//
+// So the id is asserted as a literal. A test that merely recomputed the id
+// from whatever `key` happened to be in the manifest would pass after someone
+// replaced the key — and replacing the key is exactly the change that orphans
+// every existing wallet. The value below is the promise; changing it is a
+// migration, not an edit.
+//
+// Firefox needs no key: browser_specific_settings.gecko.id declares the id
+// directly, and it is pinned here for the same reason. The Firefox e2e suite
+// depends on it too (tests/e2e/firefox/driver.js maps it to a fixed uuid), and
+// tests/e2e/firefox/reinstall.js is the empirical half — it removes the add-on
+// and installs it again and reads the vault back out.
+
+const crypto = require("crypto");
+const fs = require("fs");
+const path = require("path");
+
+const MANIFEST_DIR = path.join(__dirname, "..", "manifest");
+
+// The public half of an RSA keypair, DER-encoded SubjectPublicKeyInfo, base64.
+// The PRIVATE half is not in this repo and is not needed to build, load or
+// test anything here: it is only ever used to sign a CRX, which this repo does
+// not do.
+const CHROME_KEY =
+    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzy/G9gT4Z3Ci0HCmthUPEiCjENg+" +
+    "5meZpjdogyT7SiMfxENtHdrpDL6wGhAg1Dk0f1C67Ft8OYpMrMH3kiP2Wnt0UpHo45PY0YUU" +
+    "YzdJgbsp8u0kaykd5FFiY6FycIIFaTniMuh7wRKuNNdJWly+H3aG7qZ6nGu5PIMdb1GXUk35" +
+    "hY+yl7dz5dqFFYUCyxvWCT9XGBSYiI+XRBB/rVZjMWfWpaTmRPdOZ4+GO/Lx0OdMxKlPA/kL" +
+    "WoPot5vMlLn2FDPu6sASphiu7dKZnrINW+h/27jlHMJQS0jncB1EgqOHW0vbXrZnTveFX6UW" +
+    "+Qp86FfSkikhKtQgTW2A4mtWawIDAQAB";
+
+// chrome.storage.local for this extension lives under this id, and nowhere
+// else.
+const CHROME_EXTENSION_ID = "gipbhkogfopeahplcjhipkgpcimdpkip";
+
+const FIREFOX_EXTENSION_ID = "autistmask@sneak.berlin";
+
+// Chrome's id derivation: sha256 of the DER public key, first 16 bytes, each
+// hex digit mapped 0-f onto a-p. Written out here rather than taken on trust,
+// because the whole claim of this file is that the committed key produces that
+// id.
+function chromeExtensionId(keyBase64) {
+    const der = Buffer.from(keyBase64, "base64");
+    const digest = crypto.createHash("sha256").update(der).digest("hex");
+    return [...digest.slice(0, 32)]
+        .map((c) => String.fromCharCode(97 + parseInt(c, 16)))
+        .join("");
+}
+
+function readManifest(name) {
+    return JSON.parse(
+        fs.readFileSync(path.join(MANIFEST_DIR, name + ".json"), "utf8"),
+    );
+}
+
+describe("chrome extension identity", () => {
+    test("the manifest carries the pinned key", () => {
+        expect(readManifest("chrome").key).toBe(CHROME_KEY);
+    });
+
+    test("the key is a well-formed RSA public key", () => {
+        const der = Buffer.from(CHROME_KEY, "base64");
+        // Round-trips: a truncated or re-wrapped base64 blob would still
+        // decode to bytes, and Chrome would then derive an id from garbage.
+        expect(der.toString("base64")).toBe(CHROME_KEY);
+        const key = crypto.createPublicKey({
+            key: der,
+            format: "der",
+            type: "spki",
+        });
+        expect(key.asymmetricKeyType).toBe("rsa");
+        expect(key.asymmetricKeyDetails.modulusLength).toBe(2048);
+    });
+
+    test("the key derives the pinned extension id", () => {
+        expect(chromeExtensionId(CHROME_KEY)).toBe(CHROME_EXTENSION_ID);
+        expect(CHROME_EXTENSION_ID).toMatch(/^[a-p]{32}$/);
+    });
+
+    // The private half is a credential. It has never been in this repo and no
+    // target generates one into the working tree; this fails loudly if that
+    // ever changes, because a committed .pem is a key anyone can sign a CRX
+    // with under this extension's id.
+    test("no private key is committed anywhere in the tree", () => {
+        const tracked = require("child_process")
+            .execSync("git ls-files", {
+                cwd: path.join(__dirname, ".."),
+                encoding: "utf8",
+            })
+            .split("\n")
+            .filter(Boolean);
+        expect(tracked.filter((f) => /\.(pem|key|p12|pfx)$/i.test(f))).toEqual(
+            [],
+        );
+    });
+});
+
+describe("firefox extension identity", () => {
+    test("the manifest declares the pinned gecko id", () => {
+        const gecko = readManifest("firefox").browser_specific_settings.gecko;
+        expect(gecko.id).toBe(FIREFOX_EXTENSION_ID);
+    });
+
+    // Firefox derives nothing from the path, so no key field belongs here; one
+    // would be ignored and would only suggest the id came from somewhere else.
+    test("the firefox manifest carries no chrome key field", () => {
+        expect(readManifest("firefox").key).toBeUndefined();
+    });
+});