fix: chat functionality and extended thinking handling

- bundle/bundle.md: Add provider-anthropic with source URL and orchestrator config override
  to disable extended_thinking (foundation enables it by default, causes empty text
  responses for simple queries)
- Dockerfile: Add amplifier-module-provider-anthropic pip install for container
- backend/agui_adapter.py: Fix thinking block handling and empty text block rendering
  - Thinking blocks no longer fall through to text handler
  - Text blocks only emit START when actual content arrives
  - Handle amplifierd wire format (block_index/block_type, complete text in content_block:end)
- frontend/src/hooks/useChat.ts: Reset assistantId on TEXT_MESSAGE_END to prevent stale
  message IDs across turns
- tests/test_agui_adapter.py: Add extended thinking test coverage

Chat functionality now works end-to-end. Verified: login -> create session -> send message -> receive AI response visible in chat UI.

Generated with Amplifier

tests/test_agui_adapter.py

@@ -18,21 +18,17 @@ class TestTextBlocks:
         )
 
     def test_text_block_start(self):
-        """text_block_start → TEXT_MESSAGE_START with role='assistant' and messageId."""
+        """text_block_start → no events emitted (lazy: start is deferred to first delta)."""
         event = {
             "event_type": "content_block:start",
             "data": {"index": 0, "type": "text"},
         }
         result = self.translator.translate(event)
-        assert len(result) == 1
-        ev = result[0]
-        assert ev.type.value == "TEXT_MESSAGE_START"
-        assert ev.role == "assistant"
-        assert ev.message_id  # must have a non-empty message_id
+        assert result == []
 
     def test_text_delta(self):
-        """text_delta → TEXT_MESSAGE_CONTENT with delta='Hello '."""
-        # Start the text block first
+        """First text_delta → TEXT_MESSAGE_START then TEXT_MESSAGE_CONTENT (lazy start)."""
+        # Start the text block — no event emitted yet
         start_event = {
             "event_type": "content_block:start",
             "data": {"index": 0, "type": "text"},
@@ -47,19 +43,27 @@ class TestTextBlocks:
             },
         }
         result = self.translator.translate(delta_event)
-        assert len(result) == 1
-        ev = result[0]
-        assert ev.type.value == "TEXT_MESSAGE_CONTENT"
-        assert ev.delta == "Hello "
+        # Lazy start: first delta emits [TEXT_MESSAGE_START, TEXT_MESSAGE_CONTENT]
+        assert len(result) == 2
+        start_ev, content_ev = result
+        assert start_ev.type.value == "TEXT_MESSAGE_START"
+        assert start_ev.role == "assistant"
+        assert start_ev.message_id
+        assert content_ev.type.value == "TEXT_MESSAGE_CONTENT"
+        assert content_ev.delta == "Hello "
+        assert content_ev.message_id == start_ev.message_id
 
     def test_text_block_end(self):
-        """text_block_end → TEXT_MESSAGE_END."""
-        # Start the block first
-        start_event = {
+        """text_block_end after content → TEXT_MESSAGE_END with matching messageId."""
+        # Start block, send a delta (which lazily opens it), then close it
+        self.translator.translate({
             "event_type": "content_block:start",
             "data": {"index": 0, "type": "text"},
-        }
-        self.translator.translate(start_event)
+        })
+        self.translator.translate({
+            "event_type": "content_block:delta",
+            "data": {"index": 0, "delta": {"type": "text_delta", "text": "Hi"}},
+        })
 
         end_event = {
             "event_type": "content_block:end",
@@ -195,6 +199,110 @@ class TestToolBlocks:
         assert "structuredContent" not in d
 
 
+class TestExtendedThinking:
+    """Tests for extended thinking blocks — must produce zero AG-UI events."""
+
+    def setup_method(self):
+        self.translator = AmplifierdEventTranslator(
+            run_id="run_1", thread_id="thread_1"
+        )
+
+    # ------------------------------------------------------------------
+    # helpers
+    # ------------------------------------------------------------------
+
+    def _thinking_start(self, index: int = 0) -> dict:
+        return {
+            "event_type": "content_block:start",
+            "data": {"index": index, "type": "thinking"},
+        }
+
+    def _thinking_delta(self, text: str, index: int = 0) -> dict:
+        return {
+            "event_type": "content_block:delta",
+            "data": {"index": index, "delta": {"type": "thinking_delta", "thinking": text}},
+        }
+
+    def _thinking_end(self, index: int = 0) -> dict:
+        return {"event_type": "content_block:end", "data": {"index": index}}
+
+    def _text_start(self, index: int = 1) -> dict:
+        return {
+            "event_type": "content_block:start",
+            "data": {"index": index, "type": "text"},
+        }
+
+    def _text_delta(self, text: str, index: int = 1) -> dict:
+        return {
+            "event_type": "content_block:delta",
+            "data": {"index": index, "delta": {"type": "text_delta", "text": text}},
+        }
+
+    def _text_end(self, index: int = 1) -> dict:
+        return {"event_type": "content_block:end", "data": {"index": index}}
+
+    # ------------------------------------------------------------------
+    # tests
+    # ------------------------------------------------------------------
+
+    def test_thinking_block_produces_no_events(self):
+        """thinking start/delta/end → all return [] (thinking blocks are skipped)."""
+        assert self.translator.translate(self._thinking_start()) == []
+        assert self.translator.translate(self._thinking_delta("Let me reason…")) == []
+        assert self.translator.translate(self._thinking_end()) == []
+
+    def test_empty_text_block_produces_no_events(self):
+        """text start then immediate end with no deltas → no AG-UI events emitted."""
+        assert self.translator.translate(self._text_start()) == []
+        assert self.translator.translate(self._text_end()) == []
+
+    def test_thinking_then_empty_text_produces_no_events(self):
+        """Full sequence: thinking block + empty text block → zero AG-UI events total."""
+        events = [
+            self._thinking_start(index=0),
+            self._thinking_delta("I need to think…", index=0),
+            self._thinking_end(index=0),
+            self._text_start(index=1),
+            self._text_end(index=1),
+        ]
+        all_results = []
+        for ev in events:
+            all_results.extend(self.translator.translate(ev))
+        assert all_results == []
+
+    def test_thinking_then_nonempty_text_works(self):
+        """Thinking block (skip) then text block with actual content → START + CONTENT + END."""
+        # Thinking block — all silent
+        self.translator.translate(self._thinking_start(index=0))
+        self.translator.translate(self._thinking_delta("Reasoning…", index=0))
+        self.translator.translate(self._thinking_end(index=0))
+
+        # Text block — lazy open on first delta
+        self.translator.translate(self._text_start(index=1))
+
+        first_delta_result = self.translator.translate(self._text_delta("Hello", index=1))
+        assert len(first_delta_result) == 2
+        start_ev, content_ev = first_delta_result
+        assert start_ev.type.value == "TEXT_MESSAGE_START"
+        assert start_ev.role == "assistant"
+        message_id = start_ev.message_id
+        assert content_ev.type.value == "TEXT_MESSAGE_CONTENT"
+        assert content_ev.delta == "Hello"
+        assert content_ev.message_id == message_id
+
+        # Subsequent delta — only CONTENT (no second START)
+        second_delta_result = self.translator.translate(self._text_delta(" world", index=1))
+        assert len(second_delta_result) == 1
+        assert second_delta_result[0].type.value == "TEXT_MESSAGE_CONTENT"
+        assert second_delta_result[0].delta == " world"
+
+        # End — TEXT_MESSAGE_END because content was started
+        end_result = self.translator.translate(self._text_end(index=1))
+        assert len(end_result) == 1
+        assert end_result[0].type.value == "TEXT_MESSAGE_END"
+        assert end_result[0].message_id == message_id
+
+
 class TestLifecycle:
     """Tests for lifecycle events → AG-UI run lifecycle events."""