chore(deps): upgrade strands-agents 1.51.0 → 1.55.0

backend/pyproject.toml

@@ -56,7 +56,7 @@ dependencies = [
 [project.optional-dependencies]
 # AgentCore-specific dependencies (for inference_api)
 agentcore = [
-    "strands-agents==1.51.0",
+    "strands-agents==1.55.0",
     "strands-agents-tools==0.8.8",
 
     "aws-opentelemetry-distro==0.19.0",
@@ -71,7 +71,7 @@ agentcore = [
 
 # Voice/BidiAgent dependencies (Nova Sonic speech-to-speech)
 bidi = [
-    "strands-agents[bidi]==1.51.0",
+    "strands-agents[bidi]==1.55.0",
 ]
 
 # Document ingestion pipeline dependencies (for Lambda deployment)

backend/src/agents/main_agent/core/model_config.py

@@ -382,7 +382,7 @@ def to_bedrock_config(self) -> Dict[str, Any]:
         # allows max 4; nothing else in this codebase adds one, see the
         # position test in tests/agents/main_agent/core/test_bedrock_cache_points.py):
         #
-        #   1. toolConfig tail   — cache_tools="default" (_build_tools_cache_point)
+        #   1. toolConfig tail   — CacheConfig(tools_ttl=True) (_build_tools_cache_point)
         #   2. system tail       — SystemContentBlock list built by
         #                          AgentFactory.create_agent (the deprecated
         #                          cache_prompt config key is NOT used)
@@ -402,9 +402,9 @@ def to_bedrock_config(self) -> Dict[str, Any]:
         # ~28k-token static prefix still reads from cache on those turns.
         #
         # For a model whose id Strands doesn't recognize as cache-capable,
-        # auto strategy logs a warning and no-ops — but cache_tools and a
-        # system cachePoint are sent unconditionally once configured, so both
-        # are gated on bedrock_cache_points_supported() (the same predicate
+        # auto strategy logs a warning and no-ops — but the tools and system
+        # cachePoints are sent unconditionally once configured, so both are
+        # gated on bedrock_cache_points_supported() (the same predicate
         # Strands' auto mode uses). Requires strands-agents>=1.48.0: a
         # cachePoint trailing a non-PDF `document` attachment is rejected by
         # Bedrock's Anthropic adapter with "ValidationException ...
@@ -415,11 +415,33 @@ def to_bedrock_config(self) -> Dict[str, Any]:
         # document is the first content block. Cache hits are user-visible in
         # the cost/context badge the moment this is on.
         # See: https://github.com/strands-agents/sdk-python/issues/1966
+        # tools_ttl replaces the model-level cache_tools key, deprecated in
+        # strands-agents 1.55.0 (_warn_on_deprecated_cache_tools). The emitted
+        # block is byte-identical either way, which matters because it is the
+        # tail of the cached prefix: with cache_config.ttl unset,
+        # _build_tools_cache_point resolves ttl to None for tools_ttl=True
+        # exactly as _build_deprecated_cache_tools_point did for
+        # cache_tools="default", so both emit {"cachePoint": {"type": "default"}}
+        # with no ttl key. False (not None) on the unsupported branch pins the
+        # off state explicitly rather than falling back through the deprecated
+        # key. Since cache_config.ttl stays unset, _apply_system_cache_ttl is
+        # also a no-op — it only rewrites a TTL-less cache point when one is
+        # configured.
+        #
+        # system_prompt_ttl keeps its 1.55 default of True, which appends a
+        # system cachePoint via _should_cache_system. That is inert on every
+        # path here: the guard is `not any("cachePoint" in block ...)`, and
+        # AgentFactory.create_agent already appends its own whenever
+        # bedrock_cache_points_supported() — the same predicate, so the two
+        # can't disagree. It stays on as the safety net for a system prompt
+        # that reaches Bedrock without going through that factory.
         if self.caching_enabled:
             from strands.models import CacheConfig
-            config["cache_config"] = CacheConfig(strategy="auto")
-            if self.bedrock_cache_points_supported():
-                config["cache_tools"] = "default"
+            config["cache_config"] = CacheConfig(
+                strategy="auto",
+                system_prompt_ttl=True,
+                tools_ttl=self.bedrock_cache_points_supported(),
+            )
 
         if self.retry_config:
             from botocore.config import Config as BotocoreConfig

backend/src/agents/main_agent/voice_agent.py

@@ -5,7 +5,7 @@
 real-time voice interaction. Shares session history with text ChatAgent
 for voice-text continuity.
 
-Requires: strands-agents[bidi] extra for BidiAgent and BidiNovaSonicModel.
+Requires: strands-agents[bidi] extra for BidiAgent and BedrockNovaSonicModel.
 
 Based on the voice agent pattern from:
 https://github.com/aws-samples/sample-strands-agent-with-agentcore
@@ -23,10 +23,18 @@
 
 logger = logging.getLogger(__name__)
 
-# Optional imports — BidiAgent requires the strands bidi extra
+# Optional imports — BidiAgent requires the strands bidi extra.
+#
+# strands-agents 1.55.0 renamed the provider: the module went
+# ``models.nova_sonic`` -> ``models.bedrock`` and the class
+# ``BidiNovaSonicModel`` -> ``BedrockNovaSonicModel``. That is an ImportError,
+# which this block swallows into BIDI_AVAILABLE=False — so a stale import would
+# not crash, it would silently turn voice off everywhere with one INFO line.
+# Import the name explicitly rather than leaning on the package's lazy
+# ``__getattr__``, so a future rename fails loudly here too.
 try:
     from strands.experimental.bidi import BidiAgent
-    from strands.experimental.bidi.models.nova_sonic import BidiNovaSonicModel
+    from strands.experimental.bidi.models.bedrock import BedrockNovaSonicModel
     BIDI_AVAILABLE = True
 except ImportError:
     BIDI_AVAILABLE = False
@@ -45,7 +53,7 @@ class VoiceAgent(BaseAgent):
     Bidirectional voice agent using AWS Nova Sonic 2.
 
     Provides:
-    - Real-time speech-to-speech via BidiNovaSonicModel
+    - Real-time speech-to-speech via BedrockNovaSonicModel
     - Voice-text continuity (loads previous text chat history)
     - Separate agent_id ("voice") to avoid session state conflicts
     - Configurable voice, sample rate, and model via environment variables
@@ -95,18 +103,21 @@ def _create_agent(self) -> None:
                 EnvVars.NOVA_SONIC_MODEL_ID, Defaults.NOVA_SONIC_MODEL_ID
             )
 
-            model = BidiNovaSonicModel(
+            # 1.55.0 flattened the provider's constructor: the audio settings
+            # moved from provider_config["audio"] to the `audio` kwarg (an
+            # AudioConfig TypedDict with these same five keys), and the region
+            # moved from client_config["region"] to `region`. Both are
+            # keyword-only now.
+            model = BedrockNovaSonicModel(
                 model_id=model_id,
-                provider_config={
-                    "audio": {
-                        "voice": self._voice,
-                        "input_rate": Defaults.NOVA_SONIC_INPUT_RATE,
-                        "output_rate": Defaults.NOVA_SONIC_OUTPUT_RATE,
-                        "channels": 1,
-                        "format": "pcm",
-                    },
+                audio={
+                    "voice": self._voice,
+                    "input_rate": Defaults.NOVA_SONIC_INPUT_RATE,
+                    "output_rate": Defaults.NOVA_SONIC_OUTPUT_RATE,
+                    "channels": 1,
+                    "format": "pcm",
                 },
-                client_config={"region": os.environ.get(EnvVars.AWS_REGION, Defaults.AWS_REGION)},
+                region=os.environ.get(EnvVars.AWS_REGION, Defaults.AWS_REGION),
             )
 
             # Build voice-specific system prompt

backend/tests/agents/main_agent/core/test_bedrock_cache_points.py

@@ -8,7 +8,7 @@
 the system prompt keep the stable prefix readable from cache on those turns.
 
 Contract under test (see ModelConfig.to_bedrock_config comment):
-  1. toolConfig.tools tail  — via cache_tools="default"
+  1. toolConfig.tools tail  — via CacheConfig(tools_ttl=True)
   2. system tail            — via SystemContentBlock list from AgentFactory
   3. last user message tail — via CacheConfig(strategy="auto")
 Bedrock allows max 4 cachePoints per request; nothing else may add one, so the
@@ -37,22 +37,41 @@ def _count_cache_points(node) -> int:
 
 
 # ---------------------------------------------------------------------------
-# ModelConfig: cache_tools + support predicate
+# ModelConfig: tools caching + support predicate
 # ---------------------------------------------------------------------------
 class TestCacheToolsConfig:
-    def test_cache_tools_set_for_claude_with_caching(self):
+    def test_tools_ttl_set_for_claude_with_caching(self):
         config = ModelConfig(model_id=CLAUDE_MODEL_ID, caching_enabled=True)
-        assert config.to_bedrock_config()["cache_tools"] == "default"
+        bedrock_config = config.to_bedrock_config()
+        assert bedrock_config["cache_config"].tools_ttl is True
+        # The model-level key was deprecated in strands-agents 1.55.0
+        # (_warn_on_deprecated_cache_tools); tools_ttl supersedes it.
+        assert "cache_tools" not in bedrock_config
 
-    def test_no_cache_tools_when_caching_disabled(self):
+    def test_no_cache_config_when_caching_disabled(self):
         config = ModelConfig(model_id=CLAUDE_MODEL_ID, caching_enabled=False)
-        assert "cache_tools" not in config.to_bedrock_config()
+        bedrock_config = config.to_bedrock_config()
+        assert "cache_config" not in bedrock_config
+        assert "cache_tools" not in bedrock_config
 
-    def test_no_cache_tools_for_non_anthropic_bedrock_model(self):
+    def test_tools_ttl_off_for_non_anthropic_bedrock_model(self):
         """A model Strands' auto strategy would no-op on must not get explicit
         cachePoints either — Bedrock would reject them with ValidationException."""
         config = ModelConfig(model_id="amazon.nova-pro-v1:0", caching_enabled=True)
-        assert "cache_tools" not in config.to_bedrock_config()
+        bedrock_config = config.to_bedrock_config()
+        assert bedrock_config["cache_config"].tools_ttl is False
+        assert "cache_tools" not in bedrock_config
+
+    def test_no_ttl_configured_so_the_emitted_points_carry_none(self):
+        """cache_config.ttl must stay unset.
+
+        It is what makes tools_ttl=True emit a bare ``{"type": "default"}``
+        (byte-identical to the old cache_tools="default"), and what keeps
+        _apply_system_cache_ttl from rewriting the TTL on the cache point
+        AgentFactory places. Both sit inside the cached prefix.
+        """
+        config = ModelConfig(model_id=CLAUDE_MODEL_ID, caching_enabled=True)
+        assert config.to_bedrock_config()["cache_config"].ttl is None
 
     def test_support_predicate_false_for_non_bedrock_provider(self):
         config = ModelConfig(
@@ -187,6 +206,32 @@ def test_system_tail_is_cache_point(self, request_parts):
         # system point must survive.
         assert request_parts["system"][0] == {"text": "You are a helpful assistant."}
 
+    def test_system_blocks_hold_exactly_one_cache_point(self, request_parts):
+        """1.55's _should_cache_system must not double the point we placed.
+
+        Its guard is ``not any("cachePoint" in block ...)``, so a second point
+        can only appear if AgentFactory stops placing ours — which would move
+        the system boundary and rewrite the cached prefix. A count of 2 would
+        also be a ValidationException (adjacent cache points).
+        """
+        assert _count_cache_points(request_parts["system"]) == 1
+
+    def test_system_prompt_without_our_point_gets_exactly_one(self, model):
+        """The 1.55 safety net, for any path that bypasses AgentFactory.
+
+        Pinned deliberately: cache_config.system_prompt_ttl stays at its
+        default True, so a system prompt reaching Bedrock without our
+        trailing cachePoint still ends the static prefix at the same place
+        rather than at the tools tail.
+        """
+        request = model.format_request(
+            [{"role": "user", "content": [{"text": "hi"}]}],
+            None,
+            system_prompt_content=[{"text": "You are a helpful assistant."}],
+        )
+        assert _count_cache_points(request["system"]) == 1
+        assert request["system"][-1] == {"cachePoint": {"type": "default"}}
+
     def test_last_user_message_tail_is_cache_point(self, request_parts):
         last_user = [m for m in request_parts["messages"] if m["role"] == "user"][-1]
         assert last_user["content"][-1] == {"cachePoint": {"type": "default"}}

backend/tests/agents/main_agent/streaming/test_cancellation_state.py

@@ -152,10 +152,32 @@ def test_agent_exposes_cancel(self):
         assert callable(getattr(Agent, "cancel", None))
 
     def test_sequential_executor_honors_the_cancel_signal(self):
-        """Queued tools must be skipped once cancel is armed (new in 1.51.0)."""
+        """Queued tools must be skipped once cancel is armed (new in 1.51.0).
+
+        1.51.0 read ``agent._cancel_signal`` inline; 1.55.0 moved the same read
+        behind ``Agent._observe_cancellation``. Accept either spelling — what
+        must not disappear is the per-tool check.
+        """
         from strands.tools.executors import sequential
 
-        assert "_cancel_signal" in inspect.getsource(sequential)
+        source = inspect.getsource(sequential)
+        assert "_cancel_signal" in source or "_observe_cancellation" in source
+
+    def test_observe_cancellation_reads_the_signal_we_clear(self):
+        """``reset_cancellation_state`` clears ``agent._cancel_signal`` by name.
+
+        1.55.0's ``_observe_cancellation`` is the only reader the executor goes
+        through, and it also mirrors a caller-supplied ``_external_cancel_signal``
+        onto the internal one. We never pass ``cancel_signal`` to ``stream_async``,
+        so that stays None — but if a future change starts passing one, clearing
+        the internal signal alone would stop being enough and a cancelled turn
+        would wedge every turn after it.
+        """
+        from strands import Agent
+
+        source = inspect.getsource(Agent._observe_cancellation)
+        assert "self._cancel_signal.is_set()" in source
+        assert "_external_cancel_signal" in source
 
     def test_mcp_tool_forwards_the_cancel_signal(self):
         """The in-flight MCP call must see the signal (new in 1.51.0)."""

backend/tests/agents/main_agent/test_voice_agent.py

@@ -21,6 +21,82 @@ def test_voice_agent_is_base_agent_subclass(self):
         assert issubclass(VoiceAgent, BaseAgent)
 
 
+class TestBidiProviderContract:
+    """Bind the voice provider import against the pinned SDK.
+
+    ``voice_agent`` imports the provider inside a ``try/except ImportError``
+    that degrades to ``BIDI_AVAILABLE = False`` and one INFO line. A rename
+    upstream therefore does not crash — it silently turns voice off. That is
+    exactly what strands-agents 1.55.0 did: ``models.nova_sonic``'s
+    ``BidiNovaSonicModel`` became ``models.bedrock``'s
+    ``BedrockNovaSonicModel``.
+
+    These assertions read the pinned SDK's *source*, not a live import, because
+    ``tests.yml`` installs ``--extra agentcore --extra dev`` but not
+    ``--extra bidi``: the provider module ships in the base wheel while its
+    runtime dependencies do not, so importing it here would fail on CI even
+    when the pin is correct.
+    """
+
+    def _provider_source(self):
+        import importlib.util
+        import pathlib
+
+        spec = importlib.util.find_spec("strands.experimental.bidi")
+        assert spec is not None and spec.origin, "strands bidi package not found"
+        provider = pathlib.Path(spec.origin).parent / "models" / "bedrock.py"
+        assert provider.is_file(), (
+            f"{provider} is missing — the bidi provider module was renamed again; "
+            "update the import in agents/main_agent/voice_agent.py"
+        )
+        return provider.read_text()
+
+    def test_provider_module_defines_the_class_we_import(self):
+        assert "class BedrockNovaSonicModel" in self._provider_source()
+
+    def test_voice_agent_imports_the_current_provider_name(self):
+        """Read the module's import statements, not its prose.
+
+        The comment above the import names the old symbol on purpose, so match
+        against the parsed AST rather than the raw text.
+        """
+        import ast
+        import inspect
+
+        import agents.main_agent.voice_agent as va
+
+        imported = {
+            f"{node.module}.{alias.name}"
+            for node in ast.walk(ast.parse(inspect.getsource(va)))
+            if isinstance(node, ast.ImportFrom) and node.module
+            for alias in node.names
+        }
+        assert (
+            "strands.experimental.bidi.models.bedrock.BedrockNovaSonicModel" in imported
+        )
+        assert not any("BidiNovaSonicModel" in name for name in imported), (
+            f"stale 1.51 provider name still imported: {sorted(imported)}"
+        )
+
+    def test_provider_takes_flattened_audio_and_region_kwargs(self):
+        """1.55.0 replaced provider_config/client_config with audio/region."""
+        source = self._provider_source()
+        assert "audio: AudioConfig | None = None" in source
+        assert "region: str | None = None" in source
+        assert "provider_config" not in source
+
+    def test_audio_config_still_carries_the_five_keys_we_send(self):
+        from strands.experimental.bidi.types.model import AudioConfig
+
+        assert {"voice", "input_rate", "output_rate", "channels", "format"} <= set(
+            AudioConfig.__annotations__
+        )
+
+    def test_nova_sonic_usage_is_still_cumulative(self):
+        """VoiceAgent de-cumulates bidi_usage; a switch to deltas would double-count."""
+        assert "usage_is_cumulative = True" in self._provider_source()
+
+
 class TestVoiceConstants:
     """Req VA-2: Voice configuration constants."""