Files
praxis/server/scenarios/loader.py
T
Praxis CI be3df525d8 feat(P01-03-01,P01-03-02): Pydantic scenario schema + refund YAML
server/scenarios/schema.py defines the typed model: Scenario (id, path,
market, language, title, difficulty, failure_mode, persona, setup,
success_criteria, common_mistakes, branches[], debrief) + Branch (id,
trigger.learner_signals, outcome, failure_mode, debrief_focus) +
ScenarioDebrief (model=deepseek-v4-flash:cloud, mode=no_think, D-020).
failure_mode field present per D-009. server/scenarios/loader.py loads
YAML → Pydantic, validates at load time, raises typed ValidationError on
bad input.

scenarios/customer_service_refund_ca_v01.yaml — the v0.1 Canada Customer
Service scenario (D-010): 'Angry customer requesting refund on a damaged
product', one branch point (accept_resolution vs escalate),
failure_mode=escalates_unresolved, success criteria, common mistakes,
debrief config. Matches the RESEARCH.md example.

5 unit tests pass (valid parse, invalid raises typed error, branch
outcome Literal, branch_by_id, real YAML load). load() returns a valid
Scenario with both branches.

---ci---
phase: 1
milestone: v0.1
plan: 03
task: 03-01,03-02
status: execute
persona: data-engineer
requirements:
  covered: [REQ-SCEN-01, REQ-SCEN-FMT-01]
---/ci---
2026-08-01 13:10:00 +00:00

58 lines
1.9 KiB
Python

"""Scenario loader — YAML → Pydantic Scenario (D-018).
Loads a scenario by id from the scenarios/ directory, validates it against the
Pydantic schema, and returns a typed Scenario object. Used by the pipeline
(TASK-03-07) and the e2e smoke test.
"""
from __future__ import annotations
from pathlib import Path
import yaml
from server.scenarios.schema import Scenario, ValidationError
_DEFAULT_SCENARIOS_DIR = Path(__file__).resolve().parent.parent.parent / "scenarios"
def load(scenario_id: str, scenarios_dir: Path | None = None) -> Scenario:
"""Load and validate a scenario by id.
Args:
scenario_id: e.g. 'customer_service_refund_ca_v01' (the YAML filename stem).
scenarios_dir: override the scenarios directory (default: repo /scenarios).
Returns:
A validated Scenario object.
Raises:
FileNotFoundError: if the YAML file doesn't exist.
ValidationError: if the YAML fails schema validation (typed Pydantic error).
"""
base = scenarios_dir or _DEFAULT_SCENARIOS_DIR
path = base / f"{scenario_id}.yaml"
if not path.exists():
# Try the id-with-cs-prefix alias (RESEARCH example used 'cs_refund_ca_v01').
path = base / f"{scenario_id.replace('cs_', 'customer_service_')}.yaml"
if not path.exists():
raise FileNotFoundError(f"Scenario YAML not found: {scenario_id} in {base}")
with path.open("r", encoding="utf-8") as f:
raw = yaml.safe_load(f)
return Scenario.model_validate(raw)
def load_all(scenarios_dir: Path | None = None) -> list[Scenario]:
"""Load all scenarios in the directory (for the future scenario library)."""
base = scenarios_dir or _DEFAULT_SCENARIOS_DIR
out: list[Scenario] = []
for p in sorted(base.glob("*.yaml")):
with p.open("r", encoding="utf-8") as f:
raw = yaml.safe_load(f)
out.append(Scenario.model_validate(raw))
return out
__all__ = ["load", "load_all", "ValidationError"]