Commit everything on disk: capability text, codex and gemini sandbox switches, test updates, examples/ and mplex.py

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

test_tai.py

@@ -2569,13 +2569,39 @@ class CapabilityTests(unittest.TestCase):
     def test_yolo_variant(self):
         block = tai.capability_block(yolo=True)
         self.assertIn("Approvals are off", block)
-        self.assertIn("not read-only", block)
-        self.assertIn("only a failed tool call proves a limit", block)
+        self.assertIn("Only a failed tool call proves a limit", block)
+        self.assertNotIn("read-only", block.lower())
 
     def test_default_variant(self):
         block = tai.capability_block()
         self.assertIn("ask for approval", block)
-        self.assertIn("not read-only", block)
+        self.assertIn("Only a failed tool call proves a limit", block)
+        self.assertNotIn("read-only", block.lower())
+
+    def test_no_session_mode_mentions(self):
+        for block in (tai.capability_block(), tai.capability_block(yolo=True), tai.capability_block(auto=True)):
+            lowered = block.lower()
+            self.assertNotIn("read-only", lowered)
+            self.assertNotIn("read only", lowered)
+            self.assertNotIn("readonly", lowered)
+
+    def test_codex_sandbox_default_off(self):
+        os.environ.pop("TAI_CODEX_SANDBOX", None)
+        self.assertEqual(tai.codex_sandbox_args(), [])
+        os.environ["TAI_CODEX_SANDBOX"] = "1"
+        try:
+            self.assertEqual(tai.codex_sandbox_args(), ["--sandbox", "read-only"])
+        finally:
+            os.environ.pop("TAI_CODEX_SANDBOX", None)
+
+    def test_gemini_plan_default_off(self):
+        os.environ.pop("TAI_GEMINI_PLAN", None)
+        self.assertFalse(tai.gemini_plan_enabled())
+        os.environ["TAI_GEMINI_PLAN"] = "1"
+        try:
+            self.assertTrue(tai.gemini_plan_enabled())
+        finally:
+            os.environ.pop("TAI_GEMINI_PLAN", None)
 
     def test_apply_system_injects_capabilities(self):
         system = self.agent.messages[0]["content"]
@@ -4445,7 +4471,7 @@ class ToolArgumentsTests(unittest.TestCase):
 
 class OpencodeAgentTests(unittest.TestCase):
     def test_agent_is_not_plan(self):
-        # "plan" makes opencode inject "Plan mode ACTIVE - READ-ONLY" into the
+        # "plan" makes opencode inject a plan-mode notice into the
         # model, which then refuses to emit tai's write tool calls.
         self.assertNotEqual(tai.OPENCODE_AGENT, "plan")
         captured = {}
@@ -10563,6 +10589,8 @@ class CtxStoreTests(unittest.TestCase):
             self.assertTrue(any("c00" in line for line in lines))
             self.assertFalse(any("c04" in line for line in lines))
 
+
+
 # ---------------------------------------------------------------------------
 # The grr client behind `tai.py --tui`: strings, formats, client, stream,
 # router, page engine and the shell against a small fake grr server.