refactor: reorganize client transport and extension internals

- Split client, native, remote, serve, markdown, and SDK internals into focused packages with direct imports.
- Move local and remote transport framing/protocol helpers behind clearer module boundaries.
- Break up the extension injected DOM logic into a separate content dispatch bundle and dedicated content modules.
- Add explicit client handling for passive remote discovery without noisy PQ warnings.
- Keep behavior covered with updated unit, integration, and extension tests.

tests/test_tabs.py

@@ -1,5 +1,6 @@
 """Tests for tabs.* commands."""
 import time
+import uuid
 import pytest
 
 def test_tabs_list(browser):
@@ -67,9 +68,11 @@ def test_tabs_close_by_id(browser):
     assert tab_id not in [t["id"] for t in tabs]
 
 def test_tabs_dedupe(browser):
-    # Open the same URL twice
-    r1 = browser("navigate.open", {"url": "https://example.com", "background": True})
-    r2 = browser("navigate.open", {"url": "https://example.com", "background": True})
+    # Use a unique URL so pre-existing example.com tabs cannot be selected as
+    # the survivor while both freshly opened duplicates stay open.
+    url = f"https://example.com/?browser-cli-dedupe={uuid.uuid4().hex}"
+    r1 = browser("navigate.open", {"url": url, "background": True})
+    r2 = browser("navigate.open", {"url": url, "background": True})
     id1, id2 = r1["id"], r2["id"]
 
     try:
@@ -77,7 +80,7 @@ def test_tabs_dedupe(browser):
         # resolved a URL yet, so wait for both tabs to finish loading first.
         for _ in range(30):
             tabs = {t["id"]: t for t in browser("tabs.list")}
-            if all(tabs.get(tid, {}).get("url", "").startswith("http") for tid in (id1, id2)):
+            if all(tabs.get(tid, {}).get("url", "") == url for tid in (id1, id2)):
                 break
             time.sleep(0.1)
         else:
@@ -85,6 +88,13 @@ def test_tabs_dedupe(browser):
 
         result = browser("tabs.dedupe")
         assert isinstance(result, dict)
+        if result.get("jobId"):
+            for _ in range(100):
+                status = browser("jobs.status", {"jobId": result["jobId"]})
+                if status.get("status") in {"done", "error", "cancelled"}:
+                    result = status.get("result") or result
+                    break
+                time.sleep(0.1)
         assert result.get("closed", 0) >= 0
         # At least one of the two duplicates should be gone
         remaining = browser("tabs.list")