fix(launcher): never replace a profile state file we could not read

.gitignore

@@ -1,4 +1,4 @@
-node_modules/
+node_modules
 dist/
 build/
 out/

apps/desktop/launcher/tronbrowser

@@ -170,19 +170,42 @@ fi
 # "Always prompt for install". Pre-seed it in the profile's Local State so the
 # bundled chromium-web-store can install extensions. Best-effort (needs python3).
 if command -v python3 >/dev/null 2>&1; then
-  TB_LOCAL_STATE="$DATA/Local State" python3 - <<'PY' 2>/dev/null || true
-import json, os
+  TB_LOCAL_STATE="$DATA/Local State" python3 - <<'PY' || true
+import json, os, sys, tempfile
 p = os.environ["TB_LOCAL_STATE"]
 os.makedirs(os.path.dirname(p), exist_ok=True)
-try:
-    d = json.load(open(p)) if os.path.exists(p) else {}
-except Exception:
+# An existing file that does not parse is LEFT ALONE. Replacing it with a fresh
+# dict is how a profile gets wiped: this file holds every setting in the profile,
+# so a stub is indistinguishable from a factory reset — and the usual reason it
+# does not parse is a truncating write like the one this block used to do.
+if os.path.exists(p):
+    try:
+        with open(p) as f:
+            d = json.load(f)
+    except Exception:
+        sys.stderr.write("TronBrowser: %s did not parse — leaving it untouched.\n" % p)
+        raise SystemExit(0)
+else:
     d = {}
 exp = d.setdefault("browser", {}).setdefault("enabled_labs_experiments", [])
 flag = "extension-mime-request-handling@2"
 if flag not in exp:
     exp.append(flag)
-    json.dump(d, open(p, "w"))
+    # Land it as a rename. This file is the profile; a truncated in-place write
+    # loses every setting in it, and the next launch then reads it as unparseable.
+    fd, tmp = tempfile.mkstemp(dir=os.path.dirname(p))
+    try:
+        with os.fdopen(fd, "w") as f:
+            json.dump(d, f)
+            f.flush()
+            os.fsync(f.fileno())
+        os.replace(tmp, p)
+    except Exception:
+        try:
+            os.unlink(tmp)
+        except OSError:
+            pass
+        raise
 PY
 fi
 
@@ -240,16 +263,25 @@ if command -v python3 >/dev/null 2>&1 && [ "$SEARCH_PREV" != "$SEARCH_WANT" ]; t
   TB_ENGINE="$(search_engine_spec "$SEARCH_WANT")" \
   TB_PREV_URL="$SEARCH_PREV_URL" \
   TB_FORCE="$SEARCH_EXPLICIT" \
-  python3 - <<'PY' 2>/dev/null || true
-import json, os, tempfile
+  python3 - <<'PY' || true
+import json, os, sys, tempfile
 p = os.environ["TB_PREFS"]
 name, keyword, url = os.environ["TB_ENGINE"].split("|")
 prev_url = os.environ.get("TB_PREV_URL", "")
 force = os.environ.get("TB_FORCE") == "1"
 os.makedirs(os.path.dirname(p), exist_ok=True)
-try:
-    d = json.load(open(p)) if os.path.exists(p) else {}
-except Exception:
+# An existing file that does not parse is LEFT ALONE. Replacing it with a fresh
+# dict is how a profile gets wiped: this file holds every setting in the profile,
+# so a stub is indistinguishable from a factory reset — and the usual reason it
+# does not parse is a truncating write like the one this block used to do.
+if os.path.exists(p):
+    try:
+        with open(p) as f:
+            d = json.load(f)
+    except Exception:
+        sys.stderr.write("TronBrowser: %s did not parse — leaving it untouched.\n" % p)
+        raise SystemExit(0)
+else:
     d = {}
 
 # Only ever overwrite an engine that is absent or that we put there ourselves.
@@ -284,16 +316,39 @@ fi
 # goes through the new-tab path, which honors the chrome_url_overrides feed. Once
 # per profile, then respect the user's chrome://settings/onStartup choice.
 if command -v python3 >/dev/null 2>&1 && [ ! -f "$DATA/.tron-startup-ntp" ]; then
-  TB_PREFS="$DATA/Default/Preferences" python3 - <<'PY' 2>/dev/null || true
-import json, os
+  TB_PREFS="$DATA/Default/Preferences" python3 - <<'PY' || true
+import json, os, sys, tempfile
 p = os.environ["TB_PREFS"]
 os.makedirs(os.path.dirname(p), exist_ok=True)
-try:
-    d = json.load(open(p)) if os.path.exists(p) else {}
-except Exception:
+# An existing file that does not parse is LEFT ALONE. Replacing it with a fresh
+# dict is how a profile gets wiped: this file holds every setting in the profile,
+# so a stub is indistinguishable from a factory reset — and the usual reason it
+# does not parse is a truncating write like the one this block used to do.
+if os.path.exists(p):
+    try:
+        with open(p) as f:
+            d = json.load(f)
+    except Exception:
+        sys.stderr.write("TronBrowser: %s did not parse — leaving it untouched.\n" % p)
+        raise SystemExit(0)
+else:
     d = {}
 d.setdefault("session", {})["restore_on_startup"] = 5  # 5 = open the New Tab page
-json.dump(d, open(p, "w"))
+# Land it as a rename. This file is the profile; a truncated in-place write
+# loses every setting in it, and the next launch then reads it as unparseable.
+fd, tmp = tempfile.mkstemp(dir=os.path.dirname(p))
+try:
+    with os.fdopen(fd, "w") as f:
+        json.dump(d, f)
+        f.flush()
+        os.fsync(f.fileno())
+    os.replace(tmp, p)
+except Exception:
+    try:
+        os.unlink(tmp)
+    except OSError:
+        pass
+    raise
 PY
   mkdir -p "$DATA"; : > "$DATA/.tron-startup-ntp"
 fi

apps/desktop/test/launcher.test.ts

@@ -226,6 +226,71 @@ describe('omnibox search engine', () => {
   });
 });
 
+// --- Damaged profile ---------------------------------------------------------
+// Three blocks in the launcher edit Chromium's JSON state files. Every one of
+// them used to do `except Exception: d = {}` and then write the result — so a
+// file that failed to parse was REPLACED by a stub holding only the key that
+// block cared about. Preferences is the whole profile, which made that a silent
+// factory reset, and the usual reason it failed to parse was the non-atomic
+// write the same block did on the previous launch. These tests pin the rule:
+// a state file we cannot read is a file we do not touch.
+
+const localStatePath = (home: string) => join(home, 'profile', 'Local State');
+
+/** A profile whose JSON state files are present but corrupt. */
+function seedCorrupt(which: 'prefs' | 'localstate'): { home: string; path: string } {
+  const home = mkdtempSync(join(tmpdir(), 'tron-launcher-'));
+  homes.push(home);
+  const path = which === 'prefs' ? prefsPath(home) : localStatePath(home);
+  mkdirSync(dirname(path), { recursive: true });
+  // What a truncated write leaves behind: valid JSON's opening, then nothing.
+  writeFileSync(path, '{"default_search_provider_data": {"template_ur');
+  return { home, path };
+}
+
+describe('damaged profile', () => {
+  it('leaves an unparseable Preferences exactly as it found it', () => {
+    const { home, path } = seedCorrupt('prefs');
+    const before = readFileSync(path, 'utf8');
+    run([], { home });
+    expect(readFileSync(path, 'utf8')).toBe(before);
+  });
+
+  it('leaves an unparseable Local State exactly as it found it', () => {
+    const { home, path } = seedCorrupt('localstate');
+    const before = readFileSync(path, 'utf8');
+    run([], { home });
+    expect(readFileSync(path, 'utf8')).toBe(before);
+  });
+
+  it('says which file it refused to touch, rather than failing silently', () => {
+    const { home } = seedCorrupt('prefs');
+    const { stderr } = run([], { home });
+    expect(stderr).toContain('did not parse');
+  });
+
+  it('still launches the browser when a state file is unreadable', () => {
+    // Refusing to write must not become refusing to start.
+    const { home } = seedCorrupt('prefs');
+    const { argv } = run([], { home });
+    expect(valueOf(argv, '--user-data-dir')).toEqual([join(home, 'profile')]);
+  });
+
+  it('keeps unrelated settings when it sets the startup page', () => {
+    // The restore_on_startup block rewrites the whole file to change one key.
+    const home = mkdtempSync(join(tmpdir(), 'tron-launcher-'));
+    homes.push(home);
+    const path = prefsPath(home);
+    mkdirSync(dirname(path), { recursive: true });
+    writeFileSync(path, JSON.stringify({ bookmark_bar: { show_on_all_tabs: true }, extensions: { settings: { abc: 1 } } }));
+    run([], { home });
+    const json = JSON.parse(readFileSync(path, 'utf8'));
+    expect(json.session?.restore_on_startup).toBe(5);
+    expect(json.bookmark_bar?.show_on_all_tabs).toBe(true);
+    expect(json.extensions?.settings?.abc).toBe(1);
+  });
+});
+
 describe('engine reporting', () => {
   it('names the engine it is about to run', () => {
     const { stderr } = run([], { version: 'Chromium 141.0.0.0' });