v0.4: background reads, JS-state login signals, blind sleeps dropped

get_or_open_tab(activate=True) — added, not replaced. Read paths pass
activate=False; post flows keep the foreground for dialogs and file inputs.

check_login moved off DOM signals onto session state: fb c_user, ig/threads
ds_user_id, twitter twid, yt ytcfg.LOGGED_IN. Three platforms were reporting
OUT on a signed-in account because their composer never mounts in a hidden
tab. The fixed sleep(4)/sleep(5) before each check goes with them — every
signal reads present the moment navigate() returns.

Unreadable cookies raise instead of returning False: "cannot tell" is not
"signed out". tiktok untouched and still activated — it reported
visibilityState "visible" from a sibling-activated tab, so it has never been
read from a genuine background.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

cdp.py

@@ -22,6 +22,7 @@ import base64
 import json
 import random
 import urllib.error
+import urllib.parse
 import urllib.request
 
 import websockets
@@ -50,9 +51,10 @@ def _http_get_json(url, timeout=5.0):
         with urllib.request.urlopen(url, timeout=timeout) as resp:
             return json.loads(resp.read().decode("utf-8"))
     except urllib.error.URLError as exc:
+        port = urllib.parse.urlsplit(url).port
         raise CDPError(
             f"CDP endpoint unreachable at {url}: {exc}. "
-            "Is Brave running with --remote-debugging-port=9222?"
+            f"Is Brave running with --remote-debugging-port={port}?"
         ) from exc
     except json.JSONDecodeError as exc:
         raise CDPError(f"CDP endpoint {url} returned non-JSON: {exc}") from exc
@@ -174,15 +176,22 @@ class CDPClient:
                 return await self._attach(info["targetId"])
         raise CDPError(f"no open tab whose URL contains {url_contains!r}")
 
-    async def get_or_open_tab(self, url, url_contains):
+    async def get_or_open_tab(self, url, url_contains, activate=True):
         """Reuse a warm existing tab if one matches, otherwise open a fresh one.
         Returns (tab, reused: bool). Caller should skip tab.close() when reused.
 
-        A reused tab is brought to the front — see Tab.activate() for why a
+        A reused tab is brought to the front by default — see Tab.activate() for
-        backgrounded tab cannot be trusted to have rendered.
+        why a backgrounded tab cannot be trusted to have rendered.
+
+        `activate=False` is for callers that read a **JS-state** signal (a cookie,
+        a page global) or the network, neither of which needs a rendered page.
+        Measured 2026-09-12: X, Instagram and Threads all answer correctly with
+        `document.visibilityState == "hidden"`. It is not for the post flows —
+        those drive dialogs and file inputs, which need the foreground.
         """
         try:
             tab = await self.attach_existing(url_contains)
+            if activate:
                 await tab.activate()
             return tab, True
         except CDPError:

platforms/facebook.py

@@ -80,15 +80,22 @@ async def _flow(tab, text, media_path, visibility):
 
 
 async def check_login(cdp_client):
-    tab, reused = await cdp_client.get_or_open_tab(S["url"], "facebook.com")
+    tab, reused = await cdp_client.get_or_open_tab(S["url"], "facebook.com", activate=False)
     if reused:
         # Dismiss any leftover dialog (e.g. unsaved Create Post from a failed run)
         await tab.eval("window.onbeforeunload = null")
         await tab.navigate(S["url"])
-    await asyncio.sleep(4)
     if await tab.exists(S["login_marker"]):
         return False
-    return await tab.eval(
+    # JS state, not the composer's "on your mind" span: that string is
-        "(() => !![...document.querySelectorAll('span')].find(s => s.innerText"
+    # localised, A/B'd, and absent until the feed renders, so a signed-in
-        " && s.innerText.toLowerCase().includes('on your mind')))()"
+    # account reads as signed out. The c_user cookie is the session itself.
+    state = await tab.eval(
+        "(() => { const m = document.cookie.match(/(?:^|;\\s*)c_user=(\\d+)/);"
+        " return m ? 'in:' + m[1] : (document.cookie ? 'out' : 'unavailable'); })()"
     )
+    if state.startswith("in:"):
+        return True
+    if state == "out":
+        return False
+    raise CDPError("fb: no cookies readable on facebook.com — cannot tell signed-in from signed-out")

platforms/instagram.py

@@ -99,11 +99,21 @@ async def _wait_for_share(tab):
 
 
 async def check_login(cdp_client):
-    tab, reused = await cdp_client.get_or_open_tab(S["url"], "instagram.com")
+    tab, reused = await cdp_client.get_or_open_tab(S["url"], "instagram.com", activate=False)
     if reused:
         await tab.eval("window.onbeforeunload = null")
         await tab.navigate(S["url"])
-    await asyncio.sleep(5)
     if await tab.exists(S["login_marker"]):
         return False
-    return await tab.exists(S["new_post_svg"])
+    # JS state rather than the new-post SVG. The icon does survive a background
+    # tab today (measured 2026-09-12), but it is an icon — it moves when the nav
+    # is redesigned. The session cookie is the session.
+    state = await tab.eval(
+        "(() => { const m = document.cookie.match(/(?:^|;\\s*)ds_user_id=(\\d+)/);"
+        " return m ? 'in:' + m[1] : (document.cookie ? 'out' : 'unavailable'); })()"
+    )
+    if state.startswith("in:"):
+        return True
+    if state == "out":
+        return False
+    raise CDPError("ig: no cookies readable on instagram.com — cannot tell signed-in from signed-out")

platforms/threads.py

@@ -103,18 +103,25 @@ async def _wait_for_post_complete(tab, timeout=30.0):
 
 
 async def check_login(cdp_client):
-    tab, reused = await cdp_client.get_or_open_tab(S["url"], "threads.com")
+    tab, reused = await cdp_client.get_or_open_tab(S["url"], "threads.com", activate=False)
     if reused:
         await tab.eval("window.onbeforeunload = null")
         await tab.navigate(S["url"])
-    await asyncio.sleep(4)
     if await tab.exists(S["login_marker"]):
         return False
-    return await tab.eval(
+    # JS state, not the "What's new?" composer: that composer never mounts in a
-        "!!(document.querySelector('[placeholder=\"What\\'s new?\"]')"
+    # backgrounded tab, so a signed-in account read as signed out (measured
-        " || [...document.querySelectorAll('span,div')]"
+    # 2026-09-12 — DOM signal False while the session cookie was right there).
-        ".find(e => e.innerText && e.innerText.trim() === 'What\\'s new?'))"
+    # Threads runs on the Instagram session, hence ds_user_id.
+    state = await tab.eval(
+        "(() => { const m = document.cookie.match(/(?:^|;\\s*)ds_user_id=(\\d+)/);"
+        " return m ? 'in:' + m[1] : (document.cookie ? 'out' : 'unavailable'); })()"
     )
+    if state.startswith("in:"):
+        return True
+    if state == "out":
+        return False
+    raise CDPError("threads: no cookies readable on threads.com — cannot tell signed-in from signed-out")
 
 
 async def get_notifications(cdp_client, count=10):

platforms/tiktok.py

@@ -120,6 +120,13 @@ async def _wait_for_success(tab, timeout=120.0):
 
 
 async def check_login(cdp_client):
+    # The only platform still activated for a login check. TikTok could not be
+    # backgrounded on 2026-09-12: a sibling tab in the *same* window was
+    # activated (Browser.getWindowForTarget agreed on windowId) and TikTok still
+    # reported visibilityState "visible" — own window, or it overrides the
+    # property to keep video playing. Its DOM signal has never lied, but it has
+    # never been read from a genuine background either. Three states, not two:
+    # this stays foreground until there is evidence, not until it looks fine.
     tab, reused = await cdp_client.get_or_open_tab(S["url"], "tiktok.com")
     if reused:
         await tab.eval("window.onbeforeunload = null")

platforms/twitter.py

@@ -103,19 +103,27 @@ async def _wait_for_post_complete(tab, timeout=30.0):
 
 
 async def check_login(cdp_client):
-    tab, reused = await cdp_client.get_or_open_tab(S["url"], "x.com")
+    tab, reused = await cdp_client.get_or_open_tab(S["url"], "x.com", activate=False)
     if reused:
         await tab.eval("window.onbeforeunload = null")
         await tab.navigate(S["url"])
-    await asyncio.sleep(4)
     # If we see login markers, not logged in
     if await tab.exists(S["login_marker"]):
         return False
-    # If we see the home timeline composer, we're in
+    # JS state, not the composer. The DOM signal does mount in a background tab,
-    return await tab.eval(
+    # but only once React has painted — dropping the old sleep(4) made it read
-        "!!(document.querySelector('[data-testid=\"tweetTextarea_0\"]')"
+    # OUT on a signed-in account the moment five tabs navigated at once
-        " || document.querySelector('[data-testid=\"SideNav_NewTweet_Button\"]'))"
+    # (measured 2026-09-12). `twid` carries the user id and is set at login,
+    # same shape as fb's c_user and ig's ds_user_id.
+    state = await tab.eval(
+        "(() => { const m = document.cookie.match(/(?:^|;\\s*)twid=([^;]+)/);"
+        " return m ? 'in:' + m[1] : (document.cookie ? 'out' : 'unavailable'); })()"
     )
+    if state.startswith("in:"):
+        return True
+    if state == "out":
+        return False
+    raise CDPError("twitter: no cookies readable on x.com — cannot tell signed-in from signed-out")
 
 
 # ── Scrape tweets from a page ────────────────────────────────────────────────

platforms/youtube.py

@@ -93,14 +93,21 @@ async def _wait_for_editor_empty(tab, timeout=30.0):
 
 
 async def check_login(cdp_client):
-    tab, reused = await cdp_client.get_or_open_tab(S["url"], "youtube.com")
+    tab, reused = await cdp_client.get_or_open_tab(S["url"], "youtube.com", activate=False)
     if reused:
         await tab.eval("window.onbeforeunload = null")
         await tab.navigate(S["url"])
-    await asyncio.sleep(5)
     if await tab.exists(S["login_marker"]):
         return False
-    return await tab.eval(
+    # JS state, not the masthead DOM: #avatar-btn needs a fully rendered
-        "!!document.querySelector('#avatar-btn, button#avatar-btn,"
+    # foreground tab and reads absent for a signed-in account otherwise.
-        " ytd-topbar-menu-button-renderer #avatar-btn')"
+    # ytcfg is set by the page's own bootstrap and does not depend on render.
+    state = await tab.eval(
+        "(() => { try { return String(ytcfg.get('LOGGED_IN')); }"
+        " catch (e) { return 'unavailable'; } })()"
     )
+    if state == "true":
+        return True
+    if state == "false":
+        return False
+    raise CDPError("yt: ytcfg.LOGGED_IN unavailable — cannot tell signed-in from signed-out")