refactor(workflow): delegate transition_state to TestEntity

transition_state() now hydrates a TestEntity from the ORM model and delegates state validation to entity.transition_to(). The entity is authoritative for which transitions are valid; VALID_TRANSITIONS and can_transition() are kept for backward compatibility.

Also adds public transition_to() method to TestEntity as the stable API surface for callers that need a single validated transition without lifecycle side-effects.

backend/app/domain/test_entity.py

@@ -0,0 +1,331 @@
+"""TestEntity — pure domain object for the test lifecycle state machine.
+
+This entity owns ALL state-transition logic and business rules for a
+security test.  It has **no** dependency on FastAPI, SQLAlchemy, or any
+infrastructure concern.
+
+Usage::
+
+    entity = TestEntity.from_orm(test_orm_model)
+    entity.start_execution()          # draft → red_executing
+    entity.submit_red_evidence()      # red_executing → blue_evaluating
+    entity.pause_timer()
+    entity.resume_timer()
+    entity.submit_blue_evidence()     # blue_evaluating → in_review
+    entity.validate_red("approved")
+    entity.validate_blue("approved")  # triggers dual-validation → validated
+    entity.reopen()                   # rejected → draft
+
+After mutations, the service layer copies ``entity.changes`` back onto
+the ORM model and persists via Unit of Work.
+"""
+
+from __future__ import annotations
+
+import enum
+import uuid
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Any
+
+from app.domain.errors import BusinessRuleViolation, InvalidStateTransition
+
+
+# ── Value objects ────────────────────────────────────────────────────
+
+
+class TestState(str, enum.Enum):
+    draft = "draft"
+    red_executing = "red_executing"
+    blue_evaluating = "blue_evaluating"
+    in_review = "in_review"
+    validated = "validated"
+    rejected = "rejected"
+
+
+VALID_TRANSITIONS: dict[TestState, list[TestState]] = {
+    TestState.draft:           [TestState.red_executing],
+    TestState.red_executing:   [TestState.blue_evaluating],
+    TestState.blue_evaluating: [TestState.in_review],
+    TestState.in_review:       [TestState.validated, TestState.rejected],
+    TestState.rejected:        [TestState.draft],
+    TestState.validated:       [],
+}
+
+_PAUSABLE_STATES = frozenset({TestState.red_executing, TestState.blue_evaluating})
+
+
+# ── Domain events (lightweight records of what happened) ─────────────
+
+
+@dataclass(frozen=True)
+class DomainEvent:
+    name: str
+    payload: dict[str, Any] = field(default_factory=dict)
+
+
+# ── Entity ───────────────────────────────────────────────────────────
+
+
+@dataclass
+class TestEntity:
+    """Pure domain representation of a security test."""
+
+    id: uuid.UUID
+    state: TestState
+
+    # Red validation
+    red_validation_status: str | None = None
+    red_validated_by: uuid.UUID | None = None
+    red_validated_at: datetime | None = None
+    red_validation_notes: str | None = None
+
+    # Blue validation
+    blue_validation_status: str | None = None
+    blue_validated_by: uuid.UUID | None = None
+    blue_validated_at: datetime | None = None
+    blue_validation_notes: str | None = None
+
+    # Phase timing
+    execution_date: datetime | None = None
+    red_started_at: datetime | None = None
+    blue_started_at: datetime | None = None
+    paused_at: datetime | None = None
+    red_paused_seconds: int = 0
+    blue_paused_seconds: int = 0
+
+    # Internal bookkeeping (not persisted as-is)
+    _events: list[DomainEvent] = field(default_factory=list, repr=False)
+
+    # -- Factory --------------------------------------------------------
+
+    @classmethod
+    def from_orm(cls, model: Any) -> TestEntity:
+        """Build a TestEntity from a SQLAlchemy ``Test`` model instance."""
+        raw_state = model.state
+        state = raw_state if isinstance(raw_state, TestState) else TestState(raw_state)
+        return cls(
+            id=model.id,
+            state=state,
+            red_validation_status=model.red_validation_status,
+            red_validated_by=model.red_validated_by,
+            red_validated_at=model.red_validated_at,
+            red_validation_notes=model.red_validation_notes,
+            blue_validation_status=model.blue_validation_status,
+            blue_validated_by=model.blue_validated_by,
+            blue_validated_at=model.blue_validated_at,
+            blue_validation_notes=model.blue_validation_notes,
+            execution_date=model.execution_date,
+            red_started_at=model.red_started_at,
+            blue_started_at=model.blue_started_at,
+            paused_at=model.paused_at,
+            red_paused_seconds=model.red_paused_seconds or 0,
+            blue_paused_seconds=model.blue_paused_seconds or 0,
+        )
+
+    def apply_to(self, model: Any) -> None:
+        """Copy the entity's mutable fields back onto the ORM model."""
+        model.state = self.state
+        model.red_validation_status = self.red_validation_status
+        model.red_validated_by = self.red_validated_by
+        model.red_validated_at = self.red_validated_at
+        model.red_validation_notes = self.red_validation_notes
+        model.blue_validation_status = self.blue_validation_status
+        model.blue_validated_by = self.blue_validated_by
+        model.blue_validated_at = self.blue_validated_at
+        model.blue_validation_notes = self.blue_validation_notes
+        model.execution_date = self.execution_date
+        model.red_started_at = self.red_started_at
+        model.blue_started_at = self.blue_started_at
+        model.paused_at = self.paused_at
+        model.red_paused_seconds = self.red_paused_seconds
+        model.blue_paused_seconds = self.blue_paused_seconds
+
+    # -- Query helpers --------------------------------------------------
+
+    @property
+    def events(self) -> list[DomainEvent]:
+        return list(self._events)
+
+    def can_transition(self, target: TestState) -> bool:
+        return target in VALID_TRANSITIONS.get(self.state, [])
+
+    @property
+    def is_terminal(self) -> bool:
+        return self.state == TestState.validated
+
+    # -- Core transition ------------------------------------------------
+
+    def transition_to(self, target: TestState | str) -> str:
+        """Validate and apply a state transition.
+
+        Accepts either a :class:`TestState` member or its string value
+        (so callers using ``models.enums.TestState`` work transparently).
+
+        Returns the *previous* state value as a plain string.
+
+        Raises :class:`InvalidStateTransition` when the move is illegal.
+        """
+        resolved = target if isinstance(target, TestState) else TestState(str(target))
+        return self._transition(resolved)
+
+    def _transition(self, target: TestState) -> str:
+        """Internal: validate and apply; return previous state value."""
+        if not self.can_transition(target):
+            valid = [s.value for s in VALID_TRANSITIONS.get(self.state, [])]
+            raise InvalidStateTransition(
+                current_state=self.state.value,
+                target_state=target.value,
+                valid_transitions=valid,
+            )
+        previous = self.state.value
+        self.state = target
+        self._events.append(DomainEvent(
+            "state_changed",
+            {"previous": previous, "new": target.value},
+        ))
+        return previous
+
+    # -- Lifecycle commands --------------------------------------------
+
+    def start_execution(self) -> None:
+        """``draft`` -> ``red_executing``."""
+        self._transition(TestState.red_executing)
+        now = datetime.utcnow()
+        self.execution_date = now
+        self.red_started_at = now
+        self._events.append(DomainEvent("execution_started"))
+
+    def submit_red_evidence(self) -> int:
+        """``red_executing`` -> ``blue_evaluating``.
+
+        Auto-resumes if paused.  Returns paused seconds accumulated
+        during this phase (for worklog calculation).
+        """
+        paused_extra = self._auto_resume()
+        self._transition(TestState.blue_evaluating)
+        total_paused = self.red_paused_seconds + paused_extra
+        self.blue_started_at = datetime.utcnow()
+        self.blue_paused_seconds = 0
+        self._events.append(DomainEvent(
+            "red_evidence_submitted",
+            {"red_paused_seconds": total_paused},
+        ))
+        return total_paused
+
+    def submit_blue_evidence(self) -> int:
+        """``blue_evaluating`` -> ``in_review``.
+
+        Auto-resumes if paused.  Returns paused seconds accumulated
+        during this phase (for worklog calculation).
+        """
+        paused_extra = self._auto_resume()
+        self._transition(TestState.in_review)
+        total_paused = self.blue_paused_seconds + paused_extra
+        self._events.append(DomainEvent(
+            "blue_evidence_submitted",
+            {"blue_paused_seconds": total_paused},
+        ))
+        return total_paused
+
+    def pause_timer(self) -> None:
+        """Pause the active phase timer."""
+        if self.state not in _PAUSABLE_STATES:
+            raise BusinessRuleViolation(
+                f"Cannot pause timer in '{self.state.value}' state"
+            )
+        if self.paused_at is not None:
+            raise BusinessRuleViolation("Timer is already paused")
+        self.paused_at = datetime.utcnow()
+        self._events.append(DomainEvent("timer_paused"))
+
+    def resume_timer(self) -> int:
+        """Resume a paused timer.  Returns seconds that were paused."""
+        if self.paused_at is None:
+            raise BusinessRuleViolation("Timer is not paused")
+        now = datetime.utcnow()
+        paused_seconds = max(int((now - self.paused_at).total_seconds()), 0)
+        if self.state == TestState.red_executing:
+            self.red_paused_seconds += paused_seconds
+        elif self.state == TestState.blue_evaluating:
+            self.blue_paused_seconds += paused_seconds
+        self.paused_at = None
+        self._events.append(DomainEvent("timer_resumed", {"paused_seconds": paused_seconds}))
+        return paused_seconds
+
+    def validate_red(self, status: str, *, by: uuid.UUID, notes: str | None = None) -> None:
+        """Record Red Lead's validation decision."""
+        self._assert_in_review("red")
+        self._assert_valid_vote(status)
+        now = datetime.utcnow()
+        self.red_validation_status = status
+        self.red_validated_by = by
+        self.red_validated_at = now
+        self.red_validation_notes = notes
+        self._events.append(DomainEvent("red_validated", {"status": status}))
+        self._check_dual_validation()
+
+    def validate_blue(self, status: str, *, by: uuid.UUID, notes: str | None = None) -> None:
+        """Record Blue Lead's validation decision."""
+        self._assert_in_review("blue")
+        self._assert_valid_vote(status)
+        now = datetime.utcnow()
+        self.blue_validation_status = status
+        self.blue_validated_by = by
+        self.blue_validated_at = now
+        self.blue_validation_notes = notes
+        self._events.append(DomainEvent("blue_validated", {"status": status}))
+        self._check_dual_validation()
+
+    def reopen(self) -> None:
+        """``rejected`` -> ``draft``, clearing all validation/timing fields."""
+        self._transition(TestState.draft)
+        self.red_validation_status = None
+        self.red_validated_by = None
+        self.red_validated_at = None
+        self.red_validation_notes = None
+        self.blue_validation_status = None
+        self.blue_validated_by = None
+        self.blue_validated_at = None
+        self.blue_validation_notes = None
+        self.red_started_at = None
+        self.blue_started_at = None
+        self.paused_at = None
+        self.red_paused_seconds = 0
+        self.blue_paused_seconds = 0
+        self._events.append(DomainEvent("test_reopened"))
+
+    # -- Private -------------------------------------------------------
+
+    def _auto_resume(self) -> int:
+        """If paused, accumulate pause time and clear.  Returns extra seconds."""
+        if self.paused_at is None:
+            return 0
+        now = datetime.utcnow()
+        extra = max(int((now - self.paused_at).total_seconds()), 0)
+        self.paused_at = None
+        return extra
+
+    def _assert_in_review(self, side: str) -> None:
+        if self.state != TestState.in_review:
+            raise BusinessRuleViolation(
+                f"Cannot validate {side} side while test is in "
+                f"'{self.state.value}' state (must be in_review)"
+            )
+
+    @staticmethod
+    def _assert_valid_vote(status: str) -> None:
+        if status not in ("approved", "rejected"):
+            raise BusinessRuleViolation(
+                "validation_status must be 'approved' or 'rejected'"
+            )
+
+    def _check_dual_validation(self) -> None:
+        """If both leads have voted, advance to validated or rejected."""
+        r, b = self.red_validation_status, self.blue_validation_status
+        if r == "rejected" or b == "rejected":
+            self.state = TestState.rejected
+            self._events.append(DomainEvent("dual_validation_rejected"))
+        elif r == "approved" and b == "approved":
+            self.state = TestState.validated
+            self._events.append(DomainEvent("dual_validation_approved"))