[529f579a] Implement Prompter chat endpoint and structured task drafting (#76) (#77)

* [529f579a] feat(prompter): add PrompterService with chat and draft generation endpoints

* [529f579a] feat(prompter): add PrompterService, schemas, routes, and integration tests

* [529f579a] feat(prompter): implement session-based prompter chat endpoints with DB persistence

Add full session-based Prompter chat system with:
- Alembic migration 024 creating prompter_sessions, prompter_messages, and task_drafts tables with proper foreign keys, indexes, and enum columns
- Three new SQLAlchemy ORM table classes in roboco/db/tables.py
- Pydantic schemas: PrompterSessionCreateRequest, PrompterMessageRequest, PrompterSessionResponse, PrompterMessageResponse, TaskDraftResponse, TaskConfirmRequest
- Four new session-based FastAPI routes: POST /sessions, POST /sessions/{id}/messages, GET /sessions/{id}/draft, POST /sessions/{id}/confirm
- PrompterService with DB-backed session, message, and draft persistence; LLM-driven draft generation; ConfirmOverrides dataclass to stay under PLR0913
- Legacy stateless /chat and /draft endpoints retained for backward compatibility
- Unit tests for schemas (test_schemas_prompter.py), service pure functions and DB logic (test_prompter.py) with mocked LLM calls
- Integration tests for full happy path and legacy endpoints (test_prompter_routes.py)
- All ruff format, ruff check, mypy (changed files), and pytest checks passing

* [529f579a] fix(prompter): correct test assertion for confirmed_at field nesting

The test test_get_draft_generates_from_conversation incorrectly
accessed body['draft']['confirmed_at'] but confirmed_at is a field
on the outer TaskDraftResponse, not on the nested PrompterDraftTask.
Fixed to body['confirmed_at'].

---------

Co-authored-by: Backend Developer 2 <be-dev-2@agents.roboco.dev>

tests/unit/api/test_schemas_prompter.py

@@ -0,0 +1,212 @@
+"""Unit tests for Prompter API schemas.
+
+Covers schema validation for both the session-based and legacy schemas.
+"""
+
+from __future__ import annotations
+
+from uuid import uuid4
+
+import pytest
+from pydantic import ValidationError as PydanticValidationError
+from roboco.api.schemas.prompter import (
+    ChatMessage,
+    PrompterChatRequest,
+    PrompterDraftTask,
+    PrompterMessageRequest,
+    PrompterSessionCreateRequest,
+    TaskConfirmRequest,
+)
+
+# =============================================================================
+# ChatMessage
+# =============================================================================
+
+
+def test_chat_message_valid_roles() -> None:
+    for role in ("user", "assistant", "system"):
+        msg = ChatMessage(role=role, content="Hello")
+        assert msg.role == role
+
+
+def test_chat_message_invalid_role() -> None:
+    with pytest.raises(PydanticValidationError) as exc_info:
+        ChatMessage(role="admin", content="Hello")
+    assert "role must be one of" in str(exc_info.value)
+
+
+def test_chat_message_empty_content() -> None:
+    with pytest.raises(PydanticValidationError):
+        ChatMessage(role="user", content="")
+
+
+# =============================================================================
+# PrompterSessionCreateRequest
+# =============================================================================
+
+
+def test_session_create_request_defaults() -> None:
+    req = PrompterSessionCreateRequest()
+    assert req.context == {}
+
+
+def test_session_create_request_with_context() -> None:
+    req = PrompterSessionCreateRequest(context={"team": "backend"})
+    assert req.context == {"team": "backend"}
+
+
+# =============================================================================
+# PrompterMessageRequest
+# =============================================================================
+
+
+def test_message_request_valid() -> None:
+    req = PrompterMessageRequest(content="I need a feature")
+    assert req.content == "I need a feature"
+    assert req.context == {}
+
+
+def test_message_request_empty_content() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterMessageRequest(content="")
+
+
+def test_message_request_with_context() -> None:
+    req = PrompterMessageRequest(content="Hello", context={"key": "value"})
+    assert req.context["key"] == "value"
+
+
+# =============================================================================
+# TaskConfirmRequest
+# =============================================================================
+
+
+def test_task_confirm_request_all_optional() -> None:
+    req = TaskConfirmRequest()
+    assert req.project_id is None
+    assert req.product_id is None
+    assert req.assigned_to is None
+    assert req.overrides == {}
+
+
+def test_task_confirm_request_with_project() -> None:
+    pid = uuid4()
+    req = TaskConfirmRequest(project_id=pid)
+    assert req.project_id == pid
+
+
+# =============================================================================
+# PrompterDraftTask
+# =============================================================================
+
+
+def test_draft_task_valid() -> None:
+    draft = PrompterDraftTask(
+        title="Add login page",
+        description="Implement a secure login page with email and password",
+        acceptance_criteria=["User can log in"],
+        team="frontend",
+        task_type="code",
+        nature="technical",
+        estimated_complexity="medium",
+    )
+    assert draft.title == "Add login page"
+    assert draft.source == "prompter"
+    assert draft.confirmed_by_human is False
+
+
+def test_draft_task_title_too_long() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterDraftTask(
+            title="x" * 201,
+            description="Implement a secure login page with email and password",
+            acceptance_criteria=["User can log in"],
+            team="frontend",
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+        )
+
+
+def test_draft_task_description_too_short() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterDraftTask(
+            title="Add login page",
+            description="short",  # <20 chars
+            acceptance_criteria=["User can log in"],
+            team="frontend",
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+        )
+
+
+def test_draft_task_empty_acceptance_criteria() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterDraftTask(
+            title="Add login page",
+            description="Implement a secure login page with email and password",
+            acceptance_criteria=[],
+            team="frontend",
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+        )
+
+
+def test_draft_task_invalid_team() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterDraftTask(
+            title="Add login page",
+            description="Implement a secure login page with email and password",
+            acceptance_criteria=["User can log in"],
+            team="infra",  # invalid
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+        )
+
+
+def test_draft_task_priority_bounds() -> None:
+    # Valid bounds
+    for p in (0, 1, 2, 3):
+        d = PrompterDraftTask(
+            title="Add login page",
+            description="Implement a secure login page with email and password",
+            acceptance_criteria=["User can log in"],
+            team="frontend",
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+            priority=p,
+        )
+        assert d.priority == p
+
+    # Out of bounds
+    with pytest.raises(PydanticValidationError):
+        PrompterDraftTask(
+            title="Add login page",
+            description="Implement a secure login page with email and password",
+            acceptance_criteria=["User can log in"],
+            team="frontend",
+            task_type="code",
+            nature="technical",
+            estimated_complexity="medium",
+            priority=4,
+        )
+
+
+# =============================================================================
+# PrompterChatRequest (legacy)
+# =============================================================================
+
+
+def test_chat_request_requires_messages() -> None:
+    with pytest.raises(PydanticValidationError):
+        PrompterChatRequest(messages=[])
+
+
+def test_chat_request_valid() -> None:
+    req = PrompterChatRequest(messages=[ChatMessage(role="user", content="Hello")])
+    assert len(req.messages) == 1
+    assert req.context == {}