multi agent

agents/__init__.py

@@ -0,0 +1 @@
+from __future__ import annotations

agents/collab_runner.py

@@ -0,0 +1,184 @@
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, replace
+
+from agents.config import CollaborationConfig, load_config
+from agents.models import Observation, VerificationVerdict
+from agents.observer import Observer
+from agents.reflector import Reflector
+from agents.verifier import Verifier
+from core.models import Scene, Task, utc_now
+from runtime.context import TaskContext
+from runtime.executor import Executor
+from runtime.planner import PlannedStep, Planner
+from runtime.task import TaskRunner, TaskRunnerConfig
+from semantic.llm_client import AnthropicSemanticClient
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class CollaborativeTaskRunnerConfig:
+    max_steps: int = 20
+    max_recovery_attempts: int = 3
+
+
+class CollaborativeTaskRunner:
+    def __init__(
+        self,
+        *,
+        planner: Planner | None = None,
+        executor: Executor | None = None,
+        task_runner: TaskRunner | None = None,
+        observer: Observer | None = None,
+        verifier: Verifier | None = None,
+        reflector: Reflector | None = None,
+        config: CollaborativeTaskRunnerConfig | None = None,
+        collaboration_config: CollaborationConfig | None = None,
+        llm_client: AnthropicSemanticClient | None = None,
+    ) -> None:
+        self.planner = planner or Planner()
+        self.executor = executor or Executor()
+        self.task_runner = task_runner
+        self.observer = observer or Observer()
+        self.verifier = verifier or Verifier(client=llm_client)
+        self.reflector = reflector or Reflector(client=llm_client)
+        self.config = config or CollaborativeTaskRunnerConfig()
+        self.collaboration_config = collaboration_config or load_config()
+
+    def run(self, task: Task) -> Task:
+        if not self.collaboration_config.enabled:
+            return self._run_plain(task)
+        return self._run_collaborative(task)
+
+    def _run_plain(self, task: Task) -> Task:
+        runner = self.task_runner or TaskRunner(
+            planner=self.planner,
+            executor=self.executor,
+            config=TaskRunnerConfig(max_steps=self.config.max_steps),
+        )
+        return runner.run(task)
+
+    def _run_collaborative(self, task: Task) -> Task:
+        context = TaskContext(task_id=task.id, goal=task.goal)
+        task.status = "running"  # type: ignore[assignment]
+        task.updated_at = utc_now()
+        recovery_attempts = 0
+
+        for _ in range(self.config.max_steps):
+            scene = self._observe_scene(task.device_id)
+            context.add_scene(scene)
+
+            pre_observation = self.observer.observe(
+                scene=scene,
+                world=context.world,
+            )
+
+            steps = self.planner.plan(
+                goal=task.goal,
+                scene=scene,
+                context=context,
+            )
+            if not steps or self.planner.goal_reached(
+                goal=task.goal,
+                scene=scene,
+                context=context,
+            ):
+                task.status = "completed"  # type: ignore[assignment]
+                task.updated_at = utc_now()
+                task.completed_at = utc_now()
+                return task
+
+            for step in steps:
+                executable_step = self._step_for_device(step, task.device_id)
+                result = self.executor.execute(executable_step, context=context)
+                context.add_step_result(result)
+
+                post_scene = self._observe_scene(task.device_id)
+                post_observation = self.observer.observe(
+                    scene=post_scene,
+                    world=context.world,
+                )
+
+                verdict = self.verifier.verify(
+                    pre_observation=pre_observation,
+                    post_observation=post_observation,
+                    planned_step=step,
+                    step_result=result,
+                )
+
+                if verdict.result == "achieved":
+                    continue
+
+                if recovery_attempts >= self.collaboration_config.max_recovery_attempts:
+                    task.status = "failed"  # type: ignore[assignment]
+                    task.updated_at = utc_now()
+                    task.completed_at = utc_now()
+                    task.failure_reason = (
+                        f"Reflection recovery ceiling reached "
+                        f"({self.collaboration_config.max_recovery_attempts} attempts)"
+                    )
+                    return task
+
+                outcome = self.reflector.reflect(
+                    observation=post_observation,
+                    planned_step=step,
+                    step_result=result,
+                    verdict=verdict,
+                )
+                recovery_attempts += 1
+
+                if outcome.replan:
+                    break
+
+                if outcome.action is not None:
+                    recovery_step = PlannedStep(
+                        action=outcome.action.action,
+                        description=outcome.action.description,
+                        args=outcome.action.args,
+                    )
+                    recovery_result = self.executor.execute(
+                        self._step_for_device(recovery_step, task.device_id),
+                        context=context,
+                    )
+                    context.add_step_result(recovery_result)
+                    if not recovery_result.success:
+                        task.status = "failed"  # type: ignore[assignment]
+                        task.updated_at = utc_now()
+                        task.completed_at = utc_now()
+                        task.failure_reason = (
+                            f"Recovery action failed: {recovery_result.error}"
+                        )
+                        return task
+
+        task.status = "failed"  # type: ignore[assignment]
+        task.updated_at = utc_now()
+        task.completed_at = utc_now()
+        task.failure_reason = f"max steps exceeded: {self.config.max_steps}"
+        return task
+
+    def _observe_scene(self, device_id: str) -> Scene:
+        from tools.describe_screen import describe_screen
+
+        return describe_screen(device_id)
+
+    def _step_for_device(self, step: PlannedStep, device_id: str) -> PlannedStep:
+        device_scoped_actions = {
+            "take_screenshot",
+            "screenshot",
+            "tap",
+            "swipe",
+            "input_text",
+            "launch_app",
+            "terminate_app",
+            "get_ui_tree",
+            "ui_tree",
+            "describe_screen",
+            "describe_screen_semantic",
+            "find_text_on_screen",
+            "find_icon_on_screen",
+        }
+        if step.action not in device_scoped_actions or "device_id" in step.args:
+            return step
+        return replace(step, args={**step.args, "device_id": device_id})

agents/config.py

@@ -0,0 +1,41 @@
+from __future__ import annotations
+
+import os
+from collections.abc import Mapping
+from dataclasses import dataclass
+
+ENABLED_ENV = "MULTI_AGENT_COLLABORATION_ENABLED"
+MAX_RECOVERY_ENV = "MULTI_AGENT_MAX_RECOVERY_ATTEMPTS"
+DEFAULT_MAX_RECOVERY_ATTEMPTS = 3
+
+
+@dataclass(frozen=True)
+class CollaborationConfig:
+    enabled: bool = False
+    max_recovery_attempts: int = DEFAULT_MAX_RECOVERY_ATTEMPTS
+
+
+def load_config(env: Mapping[str, str] | None = None) -> CollaborationConfig:
+    values = env or os.environ
+    return CollaborationConfig(
+        enabled=_parse_bool(values.get(ENABLED_ENV), default=False),
+        max_recovery_attempts=_parse_int(
+            values.get(MAX_RECOVERY_ENV), default=DEFAULT_MAX_RECOVERY_ATTEMPTS
+        ),
+    )
+
+
+def _parse_bool(value: str | None, *, default: bool) -> bool:
+    if value is None:
+        return default
+    return value.strip().lower() in {"1", "true", "yes", "on", "enabled"}
+
+
+def _parse_int(value: str | None, *, default: int) -> int:
+    if value is None:
+        return default
+    try:
+        result = int(value)
+    except ValueError:
+        return default
+    return result if result > 0 else default

agents/models.py

@@ -0,0 +1,108 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Any, Literal
+
+
+@dataclass
+class Observation:
+    scene_summary: str
+    semantic_page: str | None = None
+    semantic_intents: list[str] = field(default_factory=list)
+    world_app: str | None = None
+    world_page: str | None = None
+    world_variables: dict[str, Any] = field(default_factory=dict)
+    raw_scene: dict[str, Any] | None = None
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "scene_summary": self.scene_summary,
+            "semantic_page": self.semantic_page,
+            "semantic_intents": list(self.semantic_intents),
+            "world_app": self.world_app,
+            "world_page": self.world_page,
+            "world_variables": dict(self.world_variables),
+            "raw_scene": self.raw_scene,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any]) -> Observation:
+        return cls(
+            scene_summary=str(data["scene_summary"]),
+            semantic_page=data.get("semantic_page"),
+            semantic_intents=list(data.get("semantic_intents", [])),
+            world_app=data.get("world_app"),
+            world_page=data.get("world_page"),
+            world_variables=dict(data.get("world_variables", {})),
+            raw_scene=data.get("raw_scene"),
+        )
+
+
+VerdictResult = Literal["achieved", "not_achieved"]
+
+
+@dataclass
+class VerificationVerdict:
+    result: VerdictResult
+    reasoning: str
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "result": self.result,
+            "reasoning": self.reasoning,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any]) -> VerificationVerdict:
+        result = data["result"]
+        if result not in ("achieved", "not_achieved"):
+            raise ValueError(f"invalid verdict result: {result}")
+        return cls(
+            result=result,
+            reasoning=str(data["reasoning"]),
+        )
+
+
+@dataclass
+class ReflectionAction:
+    action: str
+    description: str
+    args: dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "action": self.action,
+            "description": self.description,
+            "args": dict(self.args),
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any]) -> ReflectionAction:
+        return cls(
+            action=str(data["action"]),
+            description=str(data["description"]),
+            args=dict(data.get("args", {})),
+        )
+
+
+@dataclass
+class ReflectionOutcome:
+    replan: bool = False
+    action: ReflectionAction | None = None
+    reasoning: str = ""
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "replan": self.replan,
+            "action": self.action.to_dict() if self.action else None,
+            "reasoning": self.reasoning,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any]) -> ReflectionOutcome:
+        action_data = data.get("action")
+        return cls(
+            replan=bool(data.get("replan", False)),
+            action=ReflectionAction.from_dict(action_data) if action_data else None,
+            reasoning=str(data.get("reasoning", "")),
+        )

agents/observer.py

@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from agents.models import Observation
+from core.models import Scene, Step
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+
+if TYPE_CHECKING:
+    from semantic.models import SemanticScene
+    from world.models import WorldState
+
+
+class Observer:
+    def observe(
+        self,
+        *,
+        scene: Scene,
+        step: PlannedStep | None = None,
+        result: StepResult | None = None,
+        semantic_scene: SemanticScene | None = None,
+        world: WorldState | None = None,
+    ) -> Observation:
+        scene_summary = self._build_scene_summary(scene)
+        semantic_page = None
+        semantic_intents: list[str] = []
+        if semantic_scene is not None:
+            semantic_page = semantic_scene.page
+            semantic_intents = list(semantic_scene.intents)
+
+        world_app = None
+        world_page = None
+        world_variables: dict[str, Any] = {}
+        if world is not None:
+            world_app = world.current_app
+            world_page = world.current_page
+            world_variables = dict(world.variables)
+
+        return Observation(
+            scene_summary=scene_summary,
+            semantic_page=semantic_page,
+            semantic_intents=semantic_intents,
+            world_app=world_app,
+            world_page=world_page,
+            world_variables=world_variables,
+            raw_scene=scene.to_dict(),
+        )
+
+    def _build_scene_summary(self, scene: Scene) -> str:
+        parts = [f"Screen {scene.width}x{scene.height}"]
+        for element in scene.elements[:10]:
+            text = element.text or element.type
+            parts.append(f"  [{element.type}] {text}")
+        return "\n".join(parts)

agents/reflector.py

@@ -0,0 +1,146 @@
+from __future__ import annotations
+
+import json
+from typing import Any
+
+from agents.models import Observation, ReflectionAction, ReflectionOutcome, VerificationVerdict
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+from semantic.llm_client import AnthropicSemanticClient, EnrichmentUnavailable
+
+REFLECTOR_SYSTEM_PROMPT = """You are a reflection agent. A step failed to achieve its intended effect despite mechanical success. Your job is to propose either:
+1. A distinct recovery action (different from the failed step) that might fix the issue
+2. A replan request if no bounded corrective action is identifiable
+
+You must NEVER simply re-issue the identical failed step.
+
+Respond with JSON: {"replan": bool, "action": null or {"action": "...", "description": "...", "args": {...}}, "reasoning": "explanation"}"""
+
+REFLECTOR_JSON_SCHEMA: dict[str, Any] = {
+    "type": "object",
+    "additionalProperties": False,
+    "required": ["replan", "reasoning"],
+    "properties": {
+        "replan": {"type": "boolean"},
+        "action": {
+            "type": ["object", "null"],
+            "properties": {
+                "action": {"type": "string"},
+                "description": {"type": "string"},
+                "args": {"type": "object"},
+            },
+        },
+        "reasoning": {"type": "string", "minLength": 1},
+    },
+}
+
+
+class Reflector:
+    def __init__(self, *, client: AnthropicSemanticClient | None = None) -> None:
+        self._client = client
+
+    def reflect(
+        self,
+        *,
+        observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+        verdict: VerificationVerdict,
+    ) -> ReflectionOutcome:
+        if self._client is None:
+            return self._fallback_reflect(
+                observation=observation,
+                planned_step=planned_step,
+                step_result=step_result,
+                verdict=verdict,
+            )
+
+        try:
+            return self._llm_reflect(
+                observation=observation,
+                planned_step=planned_step,
+                step_result=step_result,
+                verdict=verdict,
+            )
+        except EnrichmentUnavailable:
+            return self._fallback_reflect(
+                observation=observation,
+                planned_step=planned_step,
+                step_result=step_result,
+                verdict=verdict,
+            )
+
+    def _llm_reflect(
+        self,
+        *,
+        observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+        verdict: VerificationVerdict,
+    ) -> ReflectionOutcome:
+        user_prompt = json.dumps(
+            {
+                "observation": observation.to_dict(),
+                "planned_step": {
+                    "action": planned_step.action,
+                    "description": planned_step.description,
+                    "args": planned_step.args,
+                    "expected_text": planned_step.expected_text,
+                },
+                "step_result": step_result.to_dict(),
+                "verdict": verdict.to_dict(),
+            },
+            ensure_ascii=False,
+        )
+        response = self._client._create_message(  # type: ignore[union-attr]
+            {"prompt": user_prompt, "system": REFLECTOR_SYSTEM_PROMPT},
+            timeout=10.0,
+        )
+        payload = _extract_outcome(response)
+        outcome = ReflectionOutcome.from_dict(payload)
+        if not outcome.replan and outcome.action is not None:
+            if outcome.action.action == planned_step.action and outcome.action.args == planned_step.args:
+                return ReflectionOutcome(
+                    replan=True,
+                    reasoning="Reflector proposed identical action; requesting replan instead.",
+                )
+        return outcome
+
+    def _fallback_reflect(
+        self,
+        *,
+        observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+        verdict: VerificationVerdict,
+    ) -> ReflectionOutcome:
+        return ReflectionOutcome(
+            replan=True,
+            reasoning=f"Step '{planned_step.description}' failed semantically; replanning (fallback).",
+        )
+
+
+def _extract_outcome(response: Any) -> dict[str, Any]:
+    if isinstance(response, dict) and "replan" in response:
+        return response
+    content = getattr(response, "content", None)
+    if isinstance(content, list):
+        for block in content:
+            text = getattr(block, "text", None)
+            if isinstance(text, str):
+                try:
+                    decoded = json.loads(text)
+                    if isinstance(decoded, dict) and "replan" in decoded:
+                        return decoded
+                except json.JSONDecodeError:
+                    continue
+            if isinstance(block, dict) and "replan" in block:
+                return block
+    if isinstance(content, str):
+        try:
+            decoded = json.loads(content)
+            if isinstance(decoded, dict) and "replan" in decoded:
+                return decoded
+        except json.JSONDecodeError:
+            pass
+    raise ValueError("could not extract reflection outcome from LLM response")

agents/verifier.py

@@ -0,0 +1,146 @@
+from __future__ import annotations
+
+import json
+from typing import Any
+
+from agents.models import Observation, VerificationVerdict
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+from semantic.llm_client import AnthropicSemanticClient, EnrichmentUnavailable
+
+VERIFIER_SYSTEM_PROMPT = """You are a verification agent. Your job is to determine whether a planned step achieved its intended effect.
+
+You will receive:
+1. A pre-step observation of the device state
+2. A post-step observation of the device state
+3. The planned step (action, description, expected outcome)
+4. The step result (whether the tool call succeeded mechanically)
+
+Analyze whether the intended effect of the step actually occurred by comparing the pre and post observations against the step's stated intent.
+
+Respond with JSON: {"result": "achieved" or "not_achieved", "reasoning": "explanation"}"""
+
+VERIFIER_JSON_SCHEMA: dict[str, Any] = {
+    "type": "object",
+    "additionalProperties": False,
+    "required": ["result", "reasoning"],
+    "properties": {
+        "result": {"type": "string", "enum": ["achieved", "not_achieved"]},
+        "reasoning": {"type": "string", "minLength": 1},
+    },
+}
+
+
+class Verifier:
+    def __init__(self, *, client: AnthropicSemanticClient | None = None) -> None:
+        self._client = client
+
+    def verify(
+        self,
+        *,
+        pre_observation: Observation,
+        post_observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+    ) -> VerificationVerdict:
+        if not step_result.success:
+            return VerificationVerdict(
+                result="not_achieved",
+                reasoning=f"Step failed mechanically: {step_result.error}",
+            )
+
+        if self._client is None:
+            return self._fallback_verify(
+                pre_observation=pre_observation,
+                post_observation=post_observation,
+                planned_step=planned_step,
+                step_result=step_result,
+            )
+
+        try:
+            return self._llm_verify(
+                pre_observation=pre_observation,
+                post_observation=post_observation,
+                planned_step=planned_step,
+                step_result=step_result,
+            )
+        except EnrichmentUnavailable:
+            return self._fallback_verify(
+                pre_observation=pre_observation,
+                post_observation=post_observation,
+                planned_step=planned_step,
+                step_result=step_result,
+            )
+
+    def _llm_verify(
+        self,
+        *,
+        pre_observation: Observation,
+        post_observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+    ) -> VerificationVerdict:
+        user_prompt = json.dumps(
+            {
+                "pre_observation": pre_observation.to_dict(),
+                "post_observation": post_observation.to_dict(),
+                "planned_step": {
+                    "action": planned_step.action,
+                    "description": planned_step.description,
+                    "args": planned_step.args,
+                    "expected_text": planned_step.expected_text,
+                },
+                "step_result": step_result.to_dict(),
+            },
+            ensure_ascii=False,
+        )
+        response = self._client._create_message(  # type: ignore[union-attr]
+            {"prompt": user_prompt, "system": VERIFIER_SYSTEM_PROMPT},
+            timeout=10.0,
+        )
+        payload = _extract_verdict(response)
+        return VerificationVerdict.from_dict(payload)
+
+    def _fallback_verify(
+        self,
+        *,
+        pre_observation: Observation,
+        post_observation: Observation,
+        planned_step: PlannedStep,
+        step_result: StepResult,
+    ) -> VerificationVerdict:
+        if pre_observation.scene_summary == post_observation.scene_summary:
+            return VerificationVerdict(
+                result="not_achieved",
+                reasoning="Scene unchanged after step execution (fallback heuristic).",
+            )
+        return VerificationVerdict(
+            result="achieved",
+            reasoning="Scene changed after step execution (fallback heuristic).",
+        )
+
+
+def _extract_verdict(response: Any) -> dict[str, Any]:
+    if isinstance(response, dict) and "result" in response:
+        return response
+    content = getattr(response, "content", None)
+    if isinstance(content, list):
+        for block in content:
+            text = getattr(block, "text", None)
+            if isinstance(text, str):
+                try:
+                    decoded = json.loads(text)
+                    if isinstance(decoded, dict) and "result" in decoded:
+                        return decoded
+                except json.JSONDecodeError:
+                    continue
+            if isinstance(block, dict) and "result" in block:
+                return block
+    if isinstance(content, str):
+        try:
+            decoded = json.loads(content)
+            if isinstance(decoded, dict) and "result" in decoded:
+                return decoded
+        except json.JSONDecodeError:
+            pass
+    raise ValueError("could not extract verification verdict from LLM response")

openspec/changes/multi-agent-runtime/tasks.md

@@ -1,48 +1,48 @@
 ## 1. Package scaffolding
 
-- [ ] 1.1 Create the `agents/` package (`__init__.py`, `models.py`, `observer.py`, `verifier.py`, `reflector.py`, `collab_runner.py`, `config.py`)
+- [x] 1.1 Create the `agents/` package (`__init__.py`, `models.py`, `observer.py`, `verifier.py`, `reflector.py`, `collab_runner.py`, `config.py`)
-- [ ] 1.2 Add an `agents*` entry to `[tool.setuptools.packages.find].include` in `pyproject.toml` (no new third-party dependency)
+- [x] 1.2 Add an `agents*` entry to `[tool.setuptools.packages.find].include` in `pyproject.toml` (no new third-party dependency)
-- [ ] 1.3 Add collaboration configuration: enabled/disabled flag (default disabled) and max-reflection-recovery-attempts ceiling, sourced from a single place `agents/config.py` reads from
+- [x] 1.3 Add collaboration configuration: enabled/disabled flag (default disabled) and max-reflection-recovery-attempts ceiling, sourced from a single place `agents/config.py` reads from
-- [ ] 1.4 Extend the project's smoke test (that imports every package) to import `agents`
+- [x] 1.4 Extend the project's smoke test (that imports every package) to import `agents`
 
 ## 2. Handoff protocol data models (capability: multi-agent-collaboration)
 
-- [ ] 2.1 Implement `agents/models.py`: `Observation`, `VerificationVerdict`, `ReflectionOutcome`, and `ReflectionAction` dataclasses with `to_dict()`/`from_dict()`, mirroring the style of `core/models.py`
+- [x] 2.1 Implement `agents/models.py`: `Observation`, `VerificationVerdict`, `ReflectionOutcome`, and `ReflectionAction` dataclasses with `to_dict()`/`from_dict()`, mirroring the style of `core/models.py`
-- [ ] 2.2 Write unit tests for each dataclass round-tripping through `to_dict()`/`from_dict()`
+- [x] 2.2 Write unit tests for each dataclass round-tripping through `to_dict()`/`from_dict()`
 
 ## 3. Observer role (capability: multi-agent-collaboration)
 
-- [ ] 3.1 Implement `agents/observer.py`: `Observer.observe(...) -> Observation`, perceiving current device state via `SemanticScene`/`WorldState` when available
+- [x] 3.1 Implement `agents/observer.py`: `Observer.observe(...) -> Observation`, perceiving current device state via `SemanticScene`/`WorldState` when available
-- [ ] 3.2 Make `Observer.observe(...)` work when `SemanticScene` and/or `WorldState` are `None`, falling back to the raw `Scene`/`PlannedStep`/`StepResult`
+- [x] 3.2 Make `Observer.observe(...)` work when `SemanticScene` and/or `WorldState` are `None`, falling back to the raw `Scene`/`PlannedStep`/`StepResult`
-- [ ] 3.3 Write unit tests for `Observer.observe(...)` covering: both `SemanticScene`/`WorldState` present, both absent, and each present individually
+- [x] 3.3 Write unit tests for `Observer.observe(...)` covering: both `SemanticScene`/`WorldState` present, both absent, and each present individually
 
 ## 4. Verifier role (capability: multi-agent-collaboration)
 
-- [ ] 4.1 Implement `agents/verifier.py`: `Verifier.verify(pre_observation, post_observation, planned_step, step_result) -> VerificationVerdict`, comparing pre-step and post-step `Observation`s against the `PlannedStep`'s stated intent
+- [x] 4.1 Implement `agents/verifier.py`: `Verifier.verify(pre_observation, post_observation, planned_step, step_result) -> VerificationVerdict`, comparing pre-step and post-step `Observation`s against the `PlannedStep`'s stated intent
-- [ ] 4.2 Wire `Verifier` to reuse `semantic/llm_client.py`'s existing LLM client abstraction (injectable/mockable) rather than a new client
+- [x] 4.2 Wire `Verifier` to reuse `semantic/llm_client.py`'s existing LLM client abstraction (injectable/mockable) rather than a new client
-- [ ] 4.3 Write unit tests for `Verifier.verify(...)` against a fake client covering: verified-achieved, verified-not-achieved, and client-failure degrade cases
+- [x] 4.3 Write unit tests for `Verifier.verify(...)` against a fake client covering: verified-achieved, verified-not-achieved, and client-failure degrade cases
 
 ## 5. Reflector role (capability: multi-agent-collaboration)
 
-- [ ] 5.1 Implement `agents/reflector.py`: `Reflector.reflect(observation, planned_step, step_result, verdict) -> ReflectionOutcome`, invoked only on a Verifier-flagged not-achieved verdict
+- [x] 5.1 Implement `agents/reflector.py`: `Reflector.reflect(observation, planned_step, step_result, verdict) -> ReflectionOutcome`, invoked only on a Verifier-flagged not-achieved verdict
-- [ ] 5.2 Ensure `Reflector.reflect(...)` never returns an outcome that simply re-issues the identical failed `PlannedStep`; it returns either a distinct `ReflectionAction` or a replan request
+- [x] 5.2 Ensure `Reflector.reflect(...)` never returns an outcome that simply re-issues the identical failed `PlannedStep`; it returns either a distinct `ReflectionAction` or a replan request
-- [ ] 5.3 Write unit tests for `Reflector.reflect(...)` covering: recovery-action outcome, replan-request outcome, and client-failure degrade case
+- [x] 5.3 Write unit tests for `Reflector.reflect(...)` covering: recovery-action outcome, replan-request outcome, and client-failure degrade case
 
 ## 6. CollaborativeTaskRunner and handoff loop (capability: multi-agent-collaboration)
 
-- [ ] 6.1 Implement `agents/collab_runner.py`: `CollaborativeTaskRunner`, composing the existing `Planner`, `Executor`, and `runtime/task.py`'s `TaskRunner` strictly by import
+- [x] 6.1 Implement `agents/collab_runner.py`: `CollaborativeTaskRunner`, composing the existing `Planner`, `Executor`, and `runtime/task.py`'s `TaskRunner` strictly by import
-- [ ] 6.2 Implement the handoff loop: Observer → Planner → Executor → Verifier → (Reflector only on a Verifier-flagged failure) → back to Observer
+- [x] 6.2 Implement the handoff loop: Observer → Planner → Executor → Verifier → (Reflector only on a Verifier-flagged failure) → back to Observer
-- [ ] 6.3 Implement the reflection-recovery ceiling: a configurable max-attempts counter, independent of and layered on top of `Executor.max_retries`, that stops further reflection-driven recovery once exhausted and surfaces the failure
+- [x] 6.3 Implement the reflection-recovery ceiling: a configurable max-attempts counter, independent of and layered on top of `Executor.max_retries`, that stops further reflection-driven recovery once exhausted and surfaces the failure
-- [ ] 6.4 Write unit tests for `CollaborativeTaskRunner` covering: a task that completes without any Verifier-flagged failure, a task recovered via one Reflector-proposed action, and a task that exhausts the reflection-recovery ceiling
+- [x] 6.4 Write unit tests for `CollaborativeTaskRunner` covering: a task that completes without any Verifier-flagged failure, a task recovered via one Reflector-proposed action, and a task that exhausts the reflection-recovery ceiling
 
 ## 7. Config wiring and opt-in behavior (capability: multi-agent-collaboration)
 
-- [ ] 7.1 Confirm collaboration is disabled by default: constructing/running a task without explicitly enabling it behaves exactly as plain `TaskRunner.run()` today
+- [x] 7.1 Confirm collaboration is disabled by default: constructing/running a task without explicitly enabling it behaves exactly as plain `TaskRunner.run()` today
-- [ ] 7.2 Write a unit test asserting `runtime/planner.py`'s `Planner`, `runtime/executor.py`'s `Executor`, and `runtime/task.py`'s `TaskRunner` are unmodified/unaffected by this change (no accidental coupling introduced from `agents/`)
+- [x] 7.2 Write a unit test asserting `runtime/planner.py`'s `Planner`, `runtime/executor.py`'s `Executor`, and `runtime/task.py`'s `TaskRunner` are unmodified/unaffected by this change (no accidental coupling introduced from `agents/`)
 
 ## 8. End-to-end validation
 
-- [ ] 8.1 Write an end-to-end test simulating a full collaborative task run against a mocked `Driver`/`Scene`/`SemanticScene`/`WorldState` and a mocked LLM client, asserting the loop completes normally whether verification succeeds or triggers reflection-driven recovery
+- [x] 8.1 Write an end-to-end test simulating a full collaborative task run against a mocked `Driver`/`Scene`/`SemanticScene`/`WorldState` and a mocked LLM client, asserting the loop completes normally whether verification succeeds or triggers reflection-driven recovery
-- [ ] 8.2 Write an integration test (skippable without network/API credentials, following the existing `apex-agent-mvp` skippable-integration-test pattern) exercising Verifier/Reflector against the real LLM client
+- [x] 8.2 Write an integration test (skippable without network/API credentials, following the existing `apex-agent-mvp` skippable-integration-test pattern) exercising Verifier/Reflector against the real LLM client
-- [ ] 8.3 Confirm multi-agent collaboration stays disabled by default after applying this change (no existing task's behavior, latency, or cost changes unless a caller explicitly opts in)
+- [x] 8.3 Confirm multi-agent collaboration stays disabled by default after applying this change (no existing task's behavior, latency, or cost changes unless a caller explicitly opts in)
-- [ ] 8.4 Run the full test suite (`pytest`) and confirm no existing test in `tests/` needed a behavior change, only additive new tests
+- [x] 8.4 Run the full test suite (`pytest`) and confirm no existing test in `tests/` needed a behavior change, only additive new tests

pyproject.toml

@@ -25,6 +25,7 @@ dev = [
 
 [tool.setuptools.packages.find]
 include = [
+    "agents*",
     "api*",
     "core*",
     "device*",

tests/test_agents_collab_runner.py

@@ -0,0 +1,191 @@
+from __future__ import annotations
+
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+from agents.collab_runner import CollaborativeTaskRunner, CollaborativeTaskRunnerConfig
+from agents.config import CollaborationConfig
+from agents.models import Observation, ReflectionAction, ReflectionOutcome, VerificationVerdict
+from core.models import Bounds, Scene, SceneElement, Task
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+
+
+def _scene() -> Scene:
+    return Scene(
+        width=1080,
+        height=1920,
+        elements=[SceneElement(id="btn1", type="button", bounds=Bounds(10, 20, 100, 50), text="OK")],
+    )
+
+
+def _task() -> Task:
+    return Task(goal="Test goal", device_id="dev1")
+
+
+def _planned_step() -> PlannedStep:
+    return PlannedStep(action="describe_screen", description="Observe", args={})
+
+
+def _success_step_result() -> StepResult:
+    return StepResult(step=_planned_step(), success=True, attempts=1, result="ok")
+
+
+def _observation() -> Observation:
+    return Observation(scene_summary="Screen 1080x1920")
+
+
+def _achieved_verdict() -> VerificationVerdict:
+    return VerificationVerdict(result="achieved", reasoning="Effect observed.")
+
+
+def _not_achieved_verdict() -> VerificationVerdict:
+    return VerificationVerdict(result="not_achieved", reasoning="No change.")
+
+
+def _replan_outcome() -> ReflectionOutcome:
+    return ReflectionOutcome(replan=True, reasoning="No recovery.")
+
+
+def _recovery_outcome() -> ReflectionOutcome:
+    return ReflectionOutcome(
+        replan=False,
+        action=ReflectionAction(action="swipe", description="Scroll", args={"direction": "up"}),
+        reasoning="Try scrolling.",
+    )
+
+
+def test_completes_without_verification_failure() -> None:
+    """Task completes normally when verifier reports achieved."""
+    planner = MagicMock()
+    planner.plan.return_value = [_planned_step()]
+    planner.goal_reached.return_value = True
+
+    executor = MagicMock()
+    executor.execute.return_value = _success_step_result()
+
+    observer = MagicMock()
+    observer.observe.return_value = _observation()
+
+    verifier = MagicMock()
+    verifier.verify.return_value = _achieved_verdict()
+
+    reflector = MagicMock()
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=observer,
+        verifier=verifier,
+        reflector=reflector,
+        config=CollaborativeTaskRunnerConfig(max_steps=5),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=3),
+    )
+
+    with patch("tools.describe_screen.describe_screen", return_value=_scene()):
+        task = runner.run(_task())
+
+    assert task.status == "completed"
+    reflector.reflect.assert_not_called()
+
+
+def test_recovers_via_reflector_action() -> None:
+    """Task recovers when reflector proposes a distinct action."""
+    call_count = 0
+
+    def verifier_side_effect(**kwargs: Any) -> VerificationVerdict:
+        nonlocal call_count
+        call_count += 1
+        if call_count == 1:
+            return _not_achieved_verdict()
+        return _achieved_verdict()
+
+    planner = MagicMock()
+    planner.plan.return_value = [_planned_step()]
+    planner.goal_reached.side_effect = [False, True]
+
+    executor = MagicMock()
+    executor.execute.return_value = _success_step_result()
+
+    observer = MagicMock()
+    observer.observe.return_value = _observation()
+
+    verifier = MagicMock()
+    verifier.verify.side_effect = verifier_side_effect
+
+    reflector = MagicMock()
+    reflector.reflect.return_value = _recovery_outcome()
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=observer,
+        verifier=verifier,
+        reflector=reflector,
+        config=CollaborativeTaskRunnerConfig(max_steps=5),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=3),
+    )
+
+    with patch("tools.describe_screen.describe_screen", return_value=_scene()):
+        task = runner.run(_task())
+
+    assert task.status == "completed"
+    reflector.reflect.assert_called_once()
+    executor.execute.assert_called()  # recovery action also executed
+
+
+def test_exhausts_recovery_ceiling() -> None:
+    """Task fails when reflection-recovery ceiling is reached."""
+    planner = MagicMock()
+    planner.plan.return_value = [_planned_step()]
+    planner.goal_reached.return_value = False
+
+    executor = MagicMock()
+    executor.execute.return_value = _success_step_result()
+
+    observer = MagicMock()
+    observer.observe.return_value = _observation()
+
+    verifier = MagicMock()
+    verifier.verify.return_value = _not_achieved_verdict()
+
+    reflector = MagicMock()
+    reflector.reflect.return_value = _replan_outcome()
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=observer,
+        verifier=verifier,
+        reflector=reflector,
+        config=CollaborativeTaskRunnerConfig(max_steps=10, max_recovery_attempts=2),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=2),
+    )
+
+    with patch("tools.describe_screen.describe_screen", return_value=_scene()):
+        task = runner.run(_task())
+
+    assert task.status == "failed"
+    assert "ceiling" in (task.failure_reason or "").lower()
+
+
+def test_disabled_collaboration_runs_plain() -> None:
+    """When collaboration is disabled, delegates to plain TaskRunner."""
+    planner = MagicMock()
+    executor = MagicMock()
+
+    mock_task_runner = MagicMock()
+    expected_task = _task()
+    expected_task.status = "completed"
+    mock_task_runner.run.return_value = expected_task
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        task_runner=mock_task_runner,
+        collaboration_config=CollaborationConfig(enabled=False),
+    )
+
+    result = runner.run(_task())
+    assert result.status == "completed"
+    mock_task_runner.run.assert_called_once()

tests/test_agents_e2e.py

@@ -0,0 +1,141 @@
+"""End-to-end tests for multi-agent collaboration (task 8.1)."""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+from agents.collab_runner import CollaborativeTaskRunner, CollaborativeTaskRunnerConfig
+from agents.config import CollaborationConfig
+from agents.models import Observation, ReflectionAction, ReflectionOutcome, VerificationVerdict
+from agents.observer import Observer
+from agents.reflector import Reflector
+from agents.verifier import Verifier
+from core.models import Bounds, Scene, SceneElement, Task
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+
+
+def _scene() -> Scene:
+    return Scene(
+        width=1080,
+        height=1920,
+        elements=[
+            SceneElement(id="btn1", type="button", bounds=Bounds(10, 20, 100, 50), text="Send"),
+        ],
+    )
+
+
+def _task() -> Task:
+    return Task(goal="Send a message", device_id="dev1")
+
+
+def test_full_loop_verification_succeeds() -> None:
+    """Full collaborative loop: plan → execute → verify (achieved) → complete."""
+    planner = MagicMock()
+    step = PlannedStep(action="tap", description="Tap send", args={"element_id": "btn1"})
+    planner.plan.return_value = [step]
+    planner.goal_reached.side_effect = [False, True]
+
+    executor = MagicMock()
+    result = StepResult(step=step, success=True, attempts=1, result={"tapped": True})
+    executor.execute.return_value = result
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=Observer(),
+        verifier=Verifier(),
+        reflector=Reflector(),
+        config=CollaborativeTaskRunnerConfig(max_steps=5),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=3),
+    )
+
+    scene = _scene()
+    with patch("tools.describe_screen.describe_screen", return_value=scene):
+        task = runner.run(_task())
+
+    assert task.status == "completed"
+
+
+def test_full_loop_with_reflection_recovery() -> None:
+    """Full loop: plan → execute → verify (not achieved) → reflect (recovery) → execute recovery → verify (achieved)."""
+    planner = MagicMock()
+    step = PlannedStep(action="tap", description="Tap send", args={"element_id": "btn1"})
+    planner.plan.return_value = [step]
+    planner.goal_reached.side_effect = [False, False, True]
+
+    executor = MagicMock()
+    success = StepResult(step=step, success=True, attempts=1, result={"tapped": True})
+    executor.execute.return_value = success
+
+    # First verify: not achieved; second verify: achieved
+    verify_call_count = 0
+
+    def verifier_verify(**kwargs):
+        nonlocal verify_call_count
+        verify_call_count += 1
+        if verify_call_count == 1:
+            return VerificationVerdict(result="not_achieved", reasoning="No change.")
+        return VerificationVerdict(result="achieved", reasoning="Done.")
+
+    verifier = MagicMock()
+    verifier.verify.side_effect = verifier_verify
+
+    reflector = MagicMock()
+    reflector.reflect.return_value = ReflectionOutcome(
+        replan=False,
+        action=ReflectionAction(action="swipe", description="Scroll", args={"direction": "up"}),
+        reasoning="Try scrolling.",
+    )
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=Observer(),
+        verifier=verifier,
+        reflector=reflector,
+        config=CollaborativeTaskRunnerConfig(max_steps=5),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=3),
+    )
+
+    scene = _scene()
+    with patch("tools.describe_screen.describe_screen", return_value=scene):
+        task = runner.run(_task())
+
+    assert task.status == "completed"
+    reflector.reflect.assert_called_once()
+
+
+def test_full_loop_exhausts_ceiling() -> None:
+    """Full loop fails when recovery ceiling is exhausted."""
+    planner = MagicMock()
+    step = PlannedStep(action="tap", description="Tap send", args={"element_id": "btn1"})
+    planner.plan.return_value = [step]
+    planner.goal_reached.return_value = False
+
+    executor = MagicMock()
+    success = StepResult(step=step, success=True, attempts=1, result={"tapped": True})
+    executor.execute.return_value = success
+
+    verifier = MagicMock()
+    verifier.verify.return_value = VerificationVerdict(result="not_achieved", reasoning="No change.")
+
+    reflector = MagicMock()
+    reflector.reflect.return_value = ReflectionOutcome(replan=True, reasoning="Replan.")
+
+    runner = CollaborativeTaskRunner(
+        planner=planner,
+        executor=executor,
+        observer=Observer(),
+        verifier=verifier,
+        reflector=reflector,
+        config=CollaborativeTaskRunnerConfig(max_steps=10, max_recovery_attempts=2),
+        collaboration_config=CollaborationConfig(enabled=True, max_recovery_attempts=2),
+    )
+
+    scene = _scene()
+    with patch("tools.describe_screen.describe_screen", return_value=scene):
+        task = runner.run(_task())
+
+    assert task.status == "failed"
+    assert "ceiling" in (task.failure_reason or "").lower()

tests/test_agents_integration.py

@@ -0,0 +1,71 @@
+"""Integration test for Verifier/Reflector against the real LLM client (task 8.2).
+Skippable without network/API credentials."""
+
+from __future__ import annotations
+
+import os
+
+import pytest
+
+from agents.models import Observation, VerificationVerdict
+from agents.reflector import Reflector
+from agents.verifier import Verifier
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+from semantic.llm_client import AnthropicSemanticClient
+
+_has_api_key = bool(os.environ.get("ANTHROPIC_API_KEY"))
+
+
+@pytest.mark.integration
+@pytest.mark.skipif(not _has_api_key, reason="ANTHROPIC_API_KEY not set")
+def test_verifier_against_real_llm() -> None:
+    client = AnthropicSemanticClient()
+    verifier = Verifier(client=client)
+
+    pre = Observation(
+        scene_summary="Screen showing a chat app with a 'Reply' button visible.",
+        semantic_page="chat",
+        semantic_intents=["send_message"],
+    )
+    post = Observation(
+        scene_summary="Screen showing a chat app with 'Message sent' confirmation visible.",
+        semantic_page="chat",
+        semantic_intents=["send_message"],
+    )
+    step = PlannedStep(action="tap", description="Tap the send button", args={})
+    result = StepResult(step=step, success=True, attempts=1, result={"tapped": True})
+
+    verdict = verifier.verify(
+        pre_observation=pre,
+        post_observation=post,
+        planned_step=step,
+        step_result=result,
+    )
+    assert verdict.result in ("achieved", "not_achieved")
+    assert verdict.reasoning
+
+
+@pytest.mark.integration
+@pytest.mark.skipif(not _has_api_key, reason="ANTHROPIC_API_KEY not set")
+def test_reflector_against_real_llm() -> None:
+    client = AnthropicSemanticClient()
+    reflector = Reflector(client=client)
+
+    observation = Observation(
+        scene_summary="Screen unchanged after tapping send button.",
+        semantic_page="chat",
+        semantic_intents=["send_message"],
+    )
+    step = PlannedStep(action="tap", description="Tap the send button", args={})
+    result = StepResult(step=step, success=True, attempts=1, result={"tapped": True})
+    verdict = VerificationVerdict(result="not_achieved", reasoning="Screen unchanged.")
+
+    outcome = reflector.reflect(
+        observation=observation,
+        planned_step=step,
+        step_result=result,
+        verdict=verdict,
+    )
+    assert outcome.replan is True or outcome.action is not None
+    assert outcome.reasoning

tests/test_agents_models.py

@@ -0,0 +1,77 @@
+from __future__ import annotations
+
+from agents.models import (
+    Observation,
+    ReflectionAction,
+    ReflectionOutcome,
+    VerificationVerdict,
+)
+
+
+def test_observation_round_trip() -> None:
+    obs = Observation(
+        scene_summary="Screen 1080x1920\n  [button] Send",
+        semantic_page="chat",
+        semantic_intents=["send_message"],
+        world_app="com.example.messenger",
+        world_page="conversation",
+        world_variables={"draft": "hello"},
+        raw_scene={"screen": {"width": 1080, "height": 1920}, "elements": []},
+    )
+    data = obs.to_dict()
+    restored = Observation.from_dict(data)
+    assert restored == obs
+
+
+def test_observation_minimal_round_trip() -> None:
+    obs = Observation(scene_summary="empty")
+    data = obs.to_dict()
+    restored = Observation.from_dict(data)
+    assert restored.scene_summary == "empty"
+    assert restored.semantic_page is None
+    assert restored.semantic_intents == []
+    assert restored.world_app is None
+    assert restored.world_page is None
+    assert restored.world_variables == {}
+    assert restored.raw_scene is None
+
+
+def test_verification_verdict_achieved_round_trip() -> None:
+    verdict = VerificationVerdict(result="achieved", reasoning="Effect observed.")
+    data = verdict.to_dict()
+    restored = VerificationVerdict.from_dict(data)
+    assert restored == verdict
+
+
+def test_verification_verdict_not_achieved_round_trip() -> None:
+    verdict = VerificationVerdict(result="not_achieved", reasoning="Scene unchanged.")
+    data = verdict.to_dict()
+    restored = VerificationVerdict.from_dict(data)
+    assert restored == verdict
+
+
+def test_reflection_action_round_trip() -> None:
+    action = ReflectionAction(
+        action="tap",
+        description="Tap the send button",
+        args={"element_id": "btn_send"},
+    )
+    data = action.to_dict()
+    restored = ReflectionAction.from_dict(data)
+    assert restored == action
+
+
+def test_reflection_outcome_with_action_round_trip() -> None:
+    action = ReflectionAction(action="tap", description="Retry tap", args={})
+    outcome = ReflectionOutcome(replan=False, action=action, reasoning="Try again.")
+    data = outcome.to_dict()
+    restored = ReflectionOutcome.from_dict(data)
+    assert restored == outcome
+
+
+def test_reflection_outcome_replan_round_trip() -> None:
+    outcome = ReflectionOutcome(replan=True, reasoning="No recovery possible.")
+    data = outcome.to_dict()
+    restored = ReflectionOutcome.from_dict(data)
+    assert restored == outcome
+    assert restored.action is None

tests/test_agents_no_coupling.py

@@ -0,0 +1,36 @@
+"""Verify that the agents/ package does not introduce accidental coupling
+into the existing runtime/ modules (task 7.2)."""
+
+from __future__ import annotations
+
+import importlib
+
+
+def test_runtime_planner_unchanged() -> None:
+    """Planner should not import from agents/."""
+    module = importlib.import_module("runtime.planner")
+    source = open(module.__file__).read()  # type: ignore[arg-type]
+    assert "agents" not in source
+
+
+def test_runtime_executor_unchanged() -> None:
+    """Executor should not import from agents/."""
+    module = importlib.import_module("runtime.executor")
+    source = open(module.__file__).read()  # type: ignore[arg-type]
+    assert "agents" not in source
+
+
+def test_runtime_task_unchanged() -> None:
+    """TaskRunner should not import from agents/."""
+    module = importlib.import_module("runtime.task")
+    source = open(module.__file__).read()  # type: ignore[arg-type]
+    assert "agents" not in source
+
+
+def test_agents_imports_runtime() -> None:
+    """agents/ should import from runtime/, not the other way around."""
+    collab = importlib.import_module("agents.collab_runner")
+    source = open(collab.__file__).read()  # type: ignore[arg-type]
+    assert "runtime.task" in source
+    assert "runtime.planner" in source
+    assert "runtime.executor" in source

tests/test_agents_observer.py

@@ -0,0 +1,85 @@
+from __future__ import annotations
+
+from collections import deque
+
+from agents.observer import Observer
+from core.models import Bounds, Scene, SceneElement
+from semantic.models import SemanticScene, SemanticWidget
+from world.models import WorldState
+
+
+def _make_scene() -> Scene:
+    return Scene(
+        width=1080,
+        height=1920,
+        elements=[
+            SceneElement(id="btn1", type="button", bounds=Bounds(10, 20, 100, 50), text="Send"),
+            SceneElement(id="txt1", type="text", bounds=Bounds(0, 0, 500, 30), text="Hello"),
+        ],
+    )
+
+
+def _make_semantic_scene() -> SemanticScene:
+    return SemanticScene(
+        page="chat",
+        intents=["send_message"],
+        widgets=[SemanticWidget(element_id="btn1", purpose="send button")],
+    )
+
+
+def _make_world() -> WorldState:
+    state = WorldState(
+        current_app="com.example.messenger",
+        current_page="conversation",
+        variables={"draft": "hello"},
+    )
+    return state
+
+
+def test_observe_with_semantic_and_world() -> None:
+    obs = Observer().observe(
+        scene=_make_scene(),
+        semantic_scene=_make_semantic_scene(),
+        world=_make_world(),
+    )
+    assert obs.semantic_page == "chat"
+    assert obs.semantic_intents == ["send_message"]
+    assert obs.world_app == "com.example.messenger"
+    assert obs.world_page == "conversation"
+    assert obs.world_variables == {"draft": "hello"}
+    assert obs.raw_scene is not None
+
+
+def test_observe_without_semantic_or_world() -> None:
+    obs = Observer().observe(scene=_make_scene())
+    assert obs.semantic_page is None
+    assert obs.semantic_intents == []
+    assert obs.world_app is None
+    assert obs.world_page is None
+    assert obs.world_variables == {}
+    assert obs.scene_summary is not None
+    assert obs.raw_scene is not None
+
+
+def test_observe_with_semantic_only() -> None:
+    obs = Observer().observe(
+        scene=_make_scene(),
+        semantic_scene=_make_semantic_scene(),
+    )
+    assert obs.semantic_page == "chat"
+    assert obs.world_app is None
+
+
+def test_observe_with_world_only() -> None:
+    obs = Observer().observe(
+        scene=_make_scene(),
+        world=_make_world(),
+    )
+    assert obs.semantic_page is None
+    assert obs.world_app == "com.example.messenger"
+
+
+def test_observe_scene_summary_includes_elements() -> None:
+    obs = Observer().observe(scene=_make_scene())
+    assert "1080x1920" in obs.scene_summary
+    assert "Send" in obs.scene_summary

tests/test_agents_reflector.py

@@ -0,0 +1,136 @@
+from __future__ import annotations
+
+from agents.models import Observation, ReflectionOutcome, VerificationVerdict
+from agents.reflector import Reflector
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+
+
+def _observation() -> Observation:
+    return Observation(scene_summary="Screen 1080x1920\n  [button] Reply")
+
+
+def _planned_step() -> PlannedStep:
+    return PlannedStep(
+        action="tap",
+        description="Tap the send button",
+        args={"element_id": "btn_send"},
+    )
+
+
+def _success_result() -> StepResult:
+    return StepResult(
+        step=_planned_step(),
+        success=True,
+        attempts=1,
+        result={"tapped": True},
+    )
+
+
+def _not_achieved_verdict() -> VerificationVerdict:
+    return VerificationVerdict(result="not_achieved", reasoning="Scene unchanged.")
+
+
+def test_reflect_fallback_returns_replan() -> None:
+    reflector = Reflector()
+    outcome = reflector.reflect(
+        observation=_observation(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+        verdict=_not_achieved_verdict(),
+    )
+    assert outcome.replan is True
+    assert outcome.action is None
+    assert "fallback" in outcome.reasoning.lower()
+
+
+class _FakeClient:
+    """A fake LLM client that returns a canned outcome."""
+
+    def __init__(self, outcome: dict) -> None:
+        self._outcome = outcome
+        self._calls: list[dict] = []
+
+    def _create_message(self, payload: dict, *, timeout: float) -> dict:
+        self._calls.append(payload)
+        return self._outcome
+
+
+def test_reflect_recovery_action_via_llm() -> None:
+    fake = _FakeClient({
+        "replan": False,
+        "action": {
+            "action": "swipe",
+            "description": "Scroll down to find send button",
+            "args": {"direction": "up"},
+        },
+        "reasoning": "Button may be off-screen.",
+    })
+    reflector = Reflector(client=fake)  # type: ignore[arg-type]
+    outcome = reflector.reflect(
+        observation=_observation(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+        verdict=_not_achieved_verdict(),
+    )
+    assert outcome.replan is False
+    assert outcome.action is not None
+    assert outcome.action.action == "swipe"
+    assert len(fake._calls) == 1
+
+
+def test_reflect_replan_via_llm() -> None:
+    fake = _FakeClient({
+        "replan": True,
+        "action": None,
+        "reasoning": "No bounded recovery possible.",
+    })
+    reflector = Reflector(client=fake)  # type: ignore[arg-type]
+    outcome = reflector.reflect(
+        observation=_observation(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+        verdict=_not_achieved_verdict(),
+    )
+    assert outcome.replan is True
+    assert outcome.action is None
+
+
+def test_reflect_rejects_identical_action() -> None:
+    """If the LLM proposes the exact same step, reflector should force replan."""
+    fake = _FakeClient({
+        "replan": False,
+        "action": {
+            "action": "tap",
+            "description": "Tap the send button",
+            "args": {"element_id": "btn_send"},
+        },
+        "reasoning": "Try again.",
+    })
+    reflector = Reflector(client=fake)  # type: ignore[arg-type]
+    outcome = reflector.reflect(
+        observation=_observation(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+        verdict=_not_achieved_verdict(),
+    )
+    assert outcome.replan is True
+    assert "identical" in outcome.reasoning.lower()
+
+
+def test_reflect_degrades_on_client_failure() -> None:
+    from semantic.llm_client import EnrichmentUnavailable
+
+    class _UnavailableClient:
+        def _create_message(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+            raise EnrichmentUnavailable("timeout")
+
+    reflector = Reflector(client=_UnavailableClient())  # type: ignore[arg-type]
+    outcome = reflector.reflect(
+        observation=_observation(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+        verdict=_not_achieved_verdict(),
+    )
+    assert outcome.replan is True
+    assert "fallback" in outcome.reasoning.lower()

tests/test_agents_verifier.py

@@ -0,0 +1,137 @@
+from __future__ import annotations
+
+from agents.models import Observation, VerificationVerdict
+from agents.verifier import Verifier
+from runtime.executor import StepResult
+from runtime.planner import PlannedStep
+
+
+def _pre_observation() -> Observation:
+    return Observation(scene_summary="Screen 1080x1920\n  [button] Reply")
+
+
+def _post_observation_changed() -> Observation:
+    return Observation(scene_summary="Screen 1080x1920\n  [text] Message sent")
+
+
+def _post_observation_unchanged() -> Observation:
+    return Observation(scene_summary="Screen 1080x1920\n  [button] Reply")
+
+
+def _planned_step() -> PlannedStep:
+    return PlannedStep(
+        action="tap",
+        description="Tap the send button",
+        args={"element_id": "btn_send"},
+    )
+
+
+def _success_result() -> StepResult:
+    return StepResult(
+        step=_planned_step(),
+        success=True,
+        attempts=1,
+        result={"tapped": True},
+    )
+
+
+def _failure_result() -> StepResult:
+    return StepResult(
+        step=_planned_step(),
+        success=False,
+        attempts=3,
+        error="element not found",
+    )
+
+
+def test_verify_not_achieved_on_mechanical_failure() -> None:
+    verifier = Verifier()
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_changed(),
+        planned_step=_planned_step(),
+        step_result=_failure_result(),
+    )
+    assert verdict.result == "not_achieved"
+    assert "failed mechanically" in verdict.reasoning.lower()
+
+
+def test_verify_achieved_fallback_scene_changed() -> None:
+    verifier = Verifier()
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_changed(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+    )
+    assert verdict.result == "achieved"
+
+
+def test_verify_not_achieved_fallback_scene_unchanged() -> None:
+    verifier = Verifier()
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_unchanged(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+    )
+    assert verdict.result == "not_achieved"
+
+
+class _FakeClient:
+    """A fake LLM client that returns a canned verdict."""
+
+    def __init__(self, verdict: dict) -> None:
+        self._verdict = verdict
+        self._calls: list[dict] = []
+
+    def _create_message(self, payload: dict, *, timeout: float) -> dict:
+        self._calls.append(payload)
+        return self._verdict
+
+
+def test_verify_achieved_via_llm() -> None:
+    fake = _FakeClient({"result": "achieved", "reasoning": "Effect observed."})
+    verifier = Verifier(client=fake)  # type: ignore[arg-type]
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_changed(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+    )
+    assert verdict.result == "achieved"
+    assert len(fake._calls) == 1
+
+
+def test_verify_not_achieved_via_llm() -> None:
+    fake = _FakeClient({"result": "not_achieved", "reasoning": "No change."})
+    verifier = Verifier(client=fake)  # type: ignore[arg-type]
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_unchanged(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+    )
+    assert verdict.result == "not_achieved"
+
+
+def test_verify_degrades_on_client_failure() -> None:
+    class _BrokenClient:
+        def _create_message(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+            raise RuntimeError("connection failed")
+
+    from semantic.llm_client import EnrichmentUnavailable
+
+    class _UnavailableClient:
+        def _create_message(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+            raise EnrichmentUnavailable("timeout")
+
+    verifier = Verifier(client=_UnavailableClient())  # type: ignore[arg-type]
+    verdict = verifier.verify(
+        pre_observation=_pre_observation(),
+        post_observation=_post_observation_changed(),
+        planned_step=_planned_step(),
+        step_result=_success_result(),
+    )
+    assert verdict.result == "achieved"
+    assert "fallback" in verdict.reasoning.lower()

tests/test_smoke.py

@@ -5,6 +5,7 @@ import importlib
 
 def test_imports_new_packages() -> None:
     for package in (
+        "agents",
         "api",
         "core",
         "device",