> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ntropii.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Task lookups

> ntro.workflow.task.previous — read the terminal output of a prior completed run of the same workflow for the same entity. Used to seed quality-check baselines for MoM deltas.

A monthly NAV run doesn't start from scratch. It needs **last period's totals** so a quality check can flag "rent dropped 12% MoM" or "journal line count is 2× the trailing average". `ntro.workflow.task` exposes task-level operations a runbook can call from inside a running workflow — `previous(...)` for prior-task lookup, `find_committed_document(...)` for retrieving committed documents.

<Note>
  **Renamed from `ntro.workflow.history` in Phase 1 of N-74.** The narrower `history` name was a poor fit once this module became the home for any task-level operation a workflow might want (`task.current()` and `task.get(task_id)` will land in Phase 2+). The instance method `self.load_previous_task(...)` on `NtroWorkflow` is unchanged and still works for terser runbook code.
</Note>

## Install

```bash theme={null}
pip install 'ntro[workflow]'
```

Bundled with the workflow extra.

## `task.previous`

```python theme={null}
@runbook.step(name="review_journal", title="Review journal", icon="Eye")
async def _step_review_journal(
    self, ctx: NavMonthlyJournalsContext, proposal: Any, tb: Any
) -> dict[str, Any]:
    # Load prior-period baseline for the quality checks. None if no
    # previous nav-monthly-journals task exists for this entity — checks
    # with `requires_baseline=True` are then marked status="skipped".
    baseline_handle = await self.load_previous_task(
        workflow_slug="nav-monthly-journals",
        entity_id=ctx.entity_slug,
        before_period=ctx.period,        # "2026-05" → most recent run < 2026-05
    )
    baseline = (
        baseline_handle.extract([
            "journal_total_debits",
            "journal_total_credits",
            "journal_line_count",
            "journal_unique_gl_codes",
        ])
        if baseline_handle
        else None
    )
    # ... pass `baseline` into run_quality_check as checks_baseline=...
```

`PreviousTaskHandle.extract(fields)` returns a flat `{field: value}` dict, dropping any fields the prior run didn't emit — the caller decides how to handle gaps. Pass the projected dict straight into [`run_quality_check`](/sdk/capabilities/quality-checks) as `checks_baseline`; checks marked `requires_baseline=True` are reported as `status="skipped"` when `baseline is None`.

<Note>
  **Soft-degrade is the contract.** `None` means "no prior task found" and is the normal first-run state. Callers should skip baseline-dependent checks rather than raise. The SDK never throws on a missing prior run.
</Note>

### Signature

```python theme={null}
async def previous(
    *,
    workflow_slug: str,            # e.g. "nav-monthly-journals"
    entity_id: str,                # entity slug or UUID
    before_period: str | None = None,   # "YYYY-MM" — most recent run strictly earlier
) -> PreviousTaskHandle | None: ...

class PreviousTaskHandle(BaseModel):
    task_id: str
    period: str | None
    output: dict[str, Any]

    def extract(self, fields: list[str]) -> dict[str, Any]: ...
```

## Wiring into a runbook

`self.load_previous_task(...)` schedules a Temporal activity under the hood. Your runbook bundle's `activities.py` **must re-export** the activity defn so the worker registers it:

```python theme={null}
# runbooks/<your-runbook>/templates/activities.py

from ntro.capabilities.checks import run_quality_check
from ntro.workflow.task import load_previous_task_activity

# Re-export the SDK's activities so the runbook bundle's activities
# discovery picks them up. Without this re-export, the worker registers
# only the activities defined locally in this module — and
# self.load_previous_task(...) would fail with "activity not registered".
__all__ = [
    "propose_journal",
    "commit_journal_proposal",
    "run_quality_check",
    "load_previous_task_activity",
]
```

The activity-decorated function names (`load_previous_task_activity`, `find_committed_document_activity`) **kept their original names** — these are network identities consumed by deployed workflows and must stay stable. Only the import path changed (`ntro.workflow.history` → `ntro.workflow.task`).

Same re-export pattern as [Quality checks](/sdk/capabilities/quality-checks). Activities live in the SDK; the runbook bundle's `__all__` is what gets registered with the worker.

## Reference

| Symbol                                                                          | Where                                                                   |
| ------------------------------------------------------------------------------- | ----------------------------------------------------------------------- |
| `previous(workflow_slug, entity_id, before_period=None)`                        | `ntro.workflow.task`                                                    |
| `find_committed_document(workflow_slug, entity_id, source, before_period=None)` | `ntro.workflow.task`                                                    |
| `load_previous_task_activity` *(re-export in runbook `__all__`)*                | `ntro.workflow.task`                                                    |
| `find_committed_document_activity` *(re-export in runbook `__all__`)*           | `ntro.workflow.task`                                                    |
| `PreviousTaskHandle` (`.task_id`, `.period`, `.output`, `.extract(fields)`)     | `ntro.workflow.task`                                                    |
| `NtroWorkflow.load_previous_task(...)`                                          | `ntro.workflow.runbook` (terser instance-method convenience; unchanged) |

## Related

<CardGroup cols={2}>
  <Card title="Quality checks" icon="shield-check" href="/sdk/capabilities/quality-checks">
    Pair the baseline dict with `run_quality_check` for MoM delta checks.
  </Card>

  <Card title="Workflows overview" icon="diagram-project" href="/workflows/runbooks/overview">
    `NtroWorkflow` and `@runbook.step` — the surface this helper extends.
  </Card>
</CardGroup>