yau-plant-assistant/api/contracts.py
Claude 40f32087a9 Take the facts back off the model
Four faults, all surfaced within an hour of the first live Azure OpenAI call
on 2026-08-27, all invisible under NO_LLM_STUB because the stub supplied the
very fields that turned out to be missing.

1. The classifier few-shot showed eight replies of {"question_class": ...}
   alone. A few-shot reply is a shape the model copies, so it omitted
   confidence, which defaulted to 0.0, fell below the 0.7 threshold, and EVERY
   non-procedural question downgraded to UNCLEAR. The replies now carry the
   complete payload the system prompt asks for. Confidences are varied and the
   traps carry alternatives: a constant teaches the model to emit that
   constant, and the tie rule in apply_safety_rules only has something to work
   with if the runners-up are populated.

2. procedure{} was the one part of the procedural payload not assembled from
   evidence, contrary to _assemble's own stated rule. The model returned
   effective_date "" - neither a date nor None - so ProceduralAnswer rejected
   the answer, the single regeneration failed identically, and every procedural
   question returned 422.

3. title and authorising_role came back "" for the same reason: the model was
   asked for header fields it had never been shown.

4. documented_limits[].citation arrived as the string "WRPS-DEMO-003, Section
   4" where a Citation was required, because the schema hint said only
   "documented_limits": [] and told the model nothing about the shape.

procedure_identity now takes no `generated` argument at all: there is no path
by which a model can name a revision an operator does not hold. documented_
limits attaches the real Citation by matching source_file against what was
actually retrieved, and DROPS a limit matching nothing - a limit carries the
authority of the document behind it, and misattributing one is worse than
omitting it.

Both live in contracts.py rather than agent.py because they are contract
rules, and because agent.py imports langgraph, which would make the test suite
unrunnable on a bare checkout.

The prompt also now separates two things it was conflating: retrieval
returning nothing (say so and stop) from retrieval returning a document marked
draft, demo or superseded (identify it, quote it, and state the marking).
Including the header chunk made the model read "NOT A CONTROLLED DOCUMENT" and
answer "no controlled procedure was retrieved" while citing one. The marking is
information the operator needs, not a reason to withhold what was found.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-28 10:54:29 +10:00

583 lines
21 KiB
Python

"""Response contracts — one per question class, validated in Python.
The three lines this system does not cross are enforced HERE, not in a prompt.
A prompt is advisory and models drift; this module is a gate every response
passes through before it can reach an operator.
The flow, implemented in agent.py:
generate -> validate -> (on failure) regenerate once -> validate
-> (on failure) raise ContractViolation and return an error
A response that fails its contract is NEVER returned, not even partially, not
even with a warning attached. There is no debug flag that disables this.
"""
from __future__ import annotations
import re
from datetime import date
from enum import Enum
from typing import Any, Literal
from pydantic import BaseModel, Field, model_validator
from config import settings
class QuestionClass(str, Enum):
"""Assigned by the classifier before any generation happens.
When uncertain, choose the MORE RESTRICTIVE class. The ordering used by
classifier.py when confidence is split:
UNCLEAR < HISTORICAL < REFERENCE < ADVISORY < PROCEDURAL
Procedural beats Reference. Advisory beats Historical. Partly-advisory is
advisory.
"""
HISTORICAL = "historical"
REFERENCE = "reference"
PROCEDURAL = "procedural"
ADVISORY = "advisory"
UNCLEAR = "unclear"
RESTRICTIVENESS: dict[QuestionClass, int] = {
QuestionClass.UNCLEAR: 0,
QuestionClass.HISTORICAL: 1,
QuestionClass.REFERENCE: 2,
QuestionClass.ADVISORY: 3,
QuestionClass.PROCEDURAL: 4,
}
class ContractViolation(Exception):
"""A generated response broke its class contract.
Carries the offending output so guardrails.py can log the whole thing to
Langfuse. It must not be included in the operator-facing error.
"""
def __init__(self, rule: str, detail: str, offending_output: str = "") -> None:
super().__init__(f"{rule}: {detail}")
self.rule = rule
self.detail = detail
self.offending_output = offending_output
# ---------------------------------------------------------------------------
# Shared pieces
# ---------------------------------------------------------------------------
class Citation(BaseModel):
"""A pointer to a controlled document. Never a paraphrase of one."""
doc_number: str
title: str
revision: str
effective_date: date | None = None
page: int | None = None
section_title: str | None = None
source_file: str
superseded: bool = False
@model_validator(mode="after")
def reject_superseded(self) -> "Citation":
# Citing a withdrawn revision is worse than finding nothing. Retrieval
# filters these out; this is the second line, in case a caller passes
# include_superseded and forgets what that means.
if self.superseded:
raise ContractViolation(
"superseded_citation",
f"{self.doc_number} rev {self.revision} is superseded",
)
return self
class TimeWindow(BaseModel):
"""Every data-dependent answer states the window it used, in site local."""
start: str
end: str
timezone: str
description: str = Field(
description="Plain words, e.g. 'rolling 7 days to 2026-08-20 09:00 AEST'"
)
class BaseAnswer(BaseModel):
question: str
question_class: QuestionClass
answer: str
used_fixture_data: bool = Field(
default=False,
description=(
"TRUE when any row behind this answer came from db/002_fixtures.sql. "
"The UI shows a banner. Never suppress it to make a demo cleaner."
),
)
stub_mode: bool = Field(
default=False,
description=(
"TRUE when NO_LLM_STUB produced this answer: no model was called, "
"the class was chosen by hand and retrieval was lexical. Carried in "
"the contract rather than added by the UI, for the same reason as "
"used_fixture_data - an answer nobody generated must not be "
"indistinguishable from one that was. See api/stub.py."
),
)
# ---------------------------------------------------------------------------
# Historical — Cube, optionally with document context
# ---------------------------------------------------------------------------
class HistoricalAnswer(BaseAnswer):
question_class: Literal[QuestionClass.HISTORICAL] = QuestionClass.HISTORICAL
query: dict[str, Any] = Field(description="The Cube query actually executed.")
row_count: int
rows: list[dict[str, Any]]
time_window: TimeWindow
citations: list[Citation] = Field(default_factory=list)
@model_validator(mode="after")
def check(self) -> "HistoricalAnswer":
if self.row_count != len(self.rows):
raise ContractViolation(
"row_count_mismatch",
f"row_count={self.row_count} but {len(self.rows)} rows attached",
self.answer,
)
if self.row_count == 0 and not _says_no_records(self.answer):
# Zero rows means "no records found", never an invented figure.
raise ContractViolation(
"zero_rows_not_declared",
"query returned no rows but the answer does not say so",
self.answer,
)
if self.row_count == 0 and _contains_quantity(
self.answer, ignoring=[self.time_window.description,
self.time_window.start, self.time_window.end]
):
raise ContractViolation(
"figure_without_data",
"answer states a quantity but the query returned no rows",
self.answer,
)
return self
# ---------------------------------------------------------------------------
# Reference — retrieval plus tag metadata
# ---------------------------------------------------------------------------
class ReferenceAnswer(BaseAnswer):
question_class: Literal[QuestionClass.REFERENCE] = QuestionClass.REFERENCE
citations: list[Citation]
tags_referenced: list[str] = Field(default_factory=list)
@model_validator(mode="after")
def check(self) -> "ReferenceAnswer":
if not self.citations and not _says_not_found(self.answer):
raise ContractViolation(
"uncited_reference",
"no citations and the answer does not say nothing was found",
self.answer,
)
return self
# ---------------------------------------------------------------------------
# Procedural — the class that must never produce instructions
# ---------------------------------------------------------------------------
class ProcedureIdentity(BaseModel):
doc_number: str
title: str
revision: str
effective_date: date | None
authorising_role: str | None = None
controlled_copy_location: str
def procedure_identity(evidence: dict[str, Any]) -> dict[str, Any] | None:
"""Which controlled document this is. Built ENTIRELY from evidence.
Every field here was at some point the model's to supply, and every one of
them failed:
* doc_number, revision, effective_date - the wrong-revision hazard. The
model returned effective_date "", which is neither a date nor None, so
ProceduralAnswer rejected the answer twice and /ask returned 422.
* title and authorising_role - returned "" whenever the header chunk was
not among the retrieved sections, which under the old similarity-ranked
find_procedure() was most of the time.
* controlled_copy_location - a site fact, the same for every document,
and the one field where an invented value sends a person to a place
that does not exist.
So none of it is the model's any more. The header fields come from the
confirmed header via doc_chunks (migration 007), the copy location from
settings. The model writes the prose and quotes the prerequisites; it does
not get a say in which document an operator is pointed at.
Returns None when nothing was retrieved. ProceduralAnswer.check() then
requires the prose to say so - a procedure asserted with no evidence behind
it is refused there, not papered over here.
"""
citations = evidence.get("citations") or []
if not citations:
return None
top = citations[0]
return {
"doc_number": top["doc_number"],
"revision": top["revision"],
"effective_date": top["effective_date"],
"title": top.get("title") or top["source_file"],
"authorising_role": _authorising_role(evidence),
"controlled_copy_location": settings().controlled_copy_location,
}
def _authorising_role(evidence: dict[str, Any]) -> str | None:
"""From the confirmed header, denormalised onto every chunk by ingest."""
for chunk in evidence.get("chunks") or []:
role = chunk.get("authorising_role")
if role:
return role
return None
class ProceduralAnswer(BaseAnswer):
"""Locate and cite. Never paraphrase, never reconstruct, never instruct.
An interlock exists because someone assessed a hazard. A bypass procedure
reassembled from retrieved fragments is a safety document nobody approved.
"""
question_class: Literal[QuestionClass.PROCEDURAL] = QuestionClass.PROCEDURAL
procedure: ProcedureIdentity | None
prerequisites_verbatim: list[str] = Field(
default_factory=list,
description="Quoted exactly from the controlled document. Not summarised.",
)
steps_provided: Literal[False] = False
citations: list[Citation]
scope_banner: str = Field(
default=(
"This assistant has identified the controlled procedure. It has not "
"reproduced or summarised the steps. Work from the controlled copy."
)
)
@model_validator(mode="after")
def check(self) -> "ProceduralAnswer":
if self.procedure is None and not _says_not_found(self.answer):
raise ContractViolation(
"no_procedure_no_refusal",
"no procedure identified and the answer does not say so",
self.answer,
)
offending = _find_instruction_language(self.answer)
if offending:
raise ContractViolation(
"synthesised_steps",
f"instruction language in a procedural answer: {offending!r}",
self.answer,
)
if _looks_like_a_step_list(self.answer):
raise ContractViolation(
"step_sequence_emitted",
"answer contains an enumerated action sequence",
self.answer,
)
if not self.scope_banner.strip():
raise ContractViolation(
"missing_scope_banner",
"procedural answers must carry the scope banner",
self.answer,
)
return self
# ---------------------------------------------------------------------------
# Advisory — evidence and a deferral, never a number presented as the answer
# ---------------------------------------------------------------------------
class Evidence(BaseModel):
"""What was actually observed. Facts with provenance, not conclusions."""
description: str
metric: str
value: float | str | None = None
unit: str | None = None
sample_size: int | None = Field(
default=None,
description="How many operations/rows this is drawn from. Always shown.",
)
time_window: TimeWindow | None = None
source: Literal["cube", "document"] = "cube"
class DocumentedLimit(BaseModel):
"""A limit somebody approved, with the document that approved it."""
description: str
value: float | str
unit: str | None = None
citation: Citation
def documented_limits(
evidence: dict[str, Any], generated: dict[str, Any]
) -> list[dict[str, Any]]:
"""Attach the real Citation to each limit the model described.
Same rule as procedure_identity(): the model says what the limit IS, the
evidence says which controlled document states it. Previously the model
supplied `citation` itself and returned the string "WRPS-DEMO-003, Section
4" where a Citation object was required, so every advisory answer failed
its contract twice and /ask returned 422.
A limit whose source_file matches nothing that was actually retrieved is
DROPPED, not attached to the nearest citation. A documented limit carries
the authority of the document behind it; pointing it at the wrong document
is worse than not stating it.
"""
by_source = {c["source_file"]: c for c in evidence.get("citations") or []}
limits = []
for limit in generated.get("documented_limits") or []:
citation = by_source.get(limit.get("source_file"))
if citation is None:
continue
limits.append({
"description": limit.get("description", ""),
"value": limit.get("value"),
"unit": limit.get("unit"),
"citation": citation,
})
return limits
class AdvisoryAnswer(BaseAnswer):
"""'Best' depends on equipment condition and concurrent operations this
system cannot see. A number presented as an answer gets typed into a
control system by someone who trusts it.
"""
question_class: Literal[QuestionClass.ADVISORY] = QuestionClass.ADVISORY
evidence: list[Evidence]
documented_limits: list[DocumentedLimit] = Field(default_factory=list)
recommendation_given: Literal[False] = False
deferral: str = Field(
description="Explicit statement of who decides and why not this system."
)
citations: list[Citation] = Field(default_factory=list)
scope_banner: str = Field(
default=(
"This assistant has presented what the plant history shows and what "
"the controlled documents state. It has not recommended a setpoint "
"or operating parameter. That decision needs a competent person with "
"sight of current equipment condition and concurrent operations."
)
)
@model_validator(mode="after")
def check(self) -> "AdvisoryAnswer":
if not self.evidence and not _says_not_found(self.answer):
raise ContractViolation(
"advisory_without_evidence",
"no evidence and no statement that none was found",
self.answer,
)
if not self.deferral.strip():
raise ContractViolation(
"missing_deferral", "advisory answers must defer explicitly", self.answer
)
offending = _find_recommendation_language(self.answer)
if offending:
raise ContractViolation(
"recommendation_given",
f"recommendation language in an advisory answer: {offending!r}",
self.answer,
)
if not self.scope_banner.strip():
raise ContractViolation(
"missing_scope_banner",
"advisory answers must carry the scope banner",
self.answer,
)
return self
# ---------------------------------------------------------------------------
# Unclear — ask, do not guess
# ---------------------------------------------------------------------------
class UnclearAnswer(BaseAnswer):
question_class: Literal[QuestionClass.UNCLEAR] = QuestionClass.UNCLEAR
clarifying_question: str
candidate_interpretations: list[str] = Field(default_factory=list)
@model_validator(mode="after")
def check(self) -> "UnclearAnswer":
if not self.clarifying_question.strip():
raise ContractViolation(
"no_clarifying_question",
"unclear class must ask something specific",
self.answer,
)
return self
Answer = (
HistoricalAnswer | ReferenceAnswer | ProceduralAnswer | AdvisoryAnswer | UnclearAnswer
)
CONTRACT_FOR: dict[QuestionClass, type[BaseAnswer]] = {
QuestionClass.HISTORICAL: HistoricalAnswer,
QuestionClass.REFERENCE: ReferenceAnswer,
QuestionClass.PROCEDURAL: ProceduralAnswer,
QuestionClass.ADVISORY: AdvisoryAnswer,
QuestionClass.UNCLEAR: UnclearAnswer,
}
# ---------------------------------------------------------------------------
# Detectors.
#
# These are blunt on purpose. A false positive costs a regeneration; a false
# negative puts a synthesised bypass procedure in front of an operator. When
# tightening one of these, add the case to eval/testset.jsonl first.
# ---------------------------------------------------------------------------
_INSTRUCTION_PATTERNS = [
r"\byou (?:should|must|need to|can|will) (?:then )?(?:navigate|press|set|turn|open|close|isolate|bypass|lift|remove|switch|select|enter|write|start|stop|reset)\b",
r"\bto (?:lift|bypass|remove|defeat|override|disable) the interlock,?\s",
r"\bfirst,?\s+(?:navigate|press|set|turn|open|close|isolate|select|go to|log in)\b",
r"\bthen,?\s+(?:navigate|press|set|turn|open|close|isolate|select|go to)\b",
r"\bnext,?\s+(?:navigate|press|set|turn|open|close|isolate|select)\b",
r"\bfollow these steps\b",
r"\bhere(?:'s| is) how to\b",
r"\bthe procedure is as follows\b",
r"\bstep 1\b",
]
_RECOMMENDATION_PATTERNS = [
r"\b(?:i|we) (?:recommend|suggest|advise)\b",
r"\b(?:the )?(?:recommended|suggested|optimal|ideal|best) (?:flowrate|flow rate|rate|setpoint|set point|speed|level|value|setting)\b",
r"\byou should (?:set|use|run|target|aim for|operate at)\b",
r"\bset (?:it|the setpoint|the level|the rate|the flow) to\b",
r"\bthe best (?:way|option|choice) (?:is|would be) to\b",
r"\baim for (?:a |an )?\d",
r"\btarget (?:a |an )?\d+(?:\.\d+)?\s*(?:%|m3/h|l/s|kpa|hz|mm)\b",
]
_NO_RECORDS_PATTERNS = [
r"\bno (?:records|rows|data|results|matching records)\b",
r"\bnothing (?:was )?(?:found|returned|recorded)\b",
r"\bdid not return any\b",
r"\bthere (?:are|were) no\b",
r"\bno (?:such )?(?:alarms?|events?|operations?|occurrences?)\b",
]
_NOT_FOUND_PATTERNS = _NO_RECORDS_PATTERNS + [
r"\bcould not (?:find|locate|identify)\b",
r"\bno (?:controlled )?(?:procedure|document|documents?)\b",
r"\bnot (?:available|held|in the document set)\b",
r"\bi (?:do not|don't) have\b",
]
# A number that reads as a quantity: 6, 6.2, 6 times, 42%. Deliberately excludes
# dates and tag numbers, which are identity, not measurement.
_QUANTITY = re.compile(
r"(?<![\w./-])\d+(?:\.\d+)?\s*(?:times|occurrences|%|m3/h|L/s|kPa|Hz|mm|hours|h|s)?(?![\w./-])",
re.IGNORECASE,
)
_STEP_LIST = re.compile(r"^\s*(?:\d+[.)]|step\s+\d+\b)", re.IGNORECASE | re.MULTILINE)
def _first_match(text: str, patterns: list[str]) -> str | None:
for pattern in patterns:
found = re.search(pattern, text, re.IGNORECASE)
if found:
return found.group(0)
return None
def _find_instruction_language(text: str) -> str | None:
return _first_match(text, _INSTRUCTION_PATTERNS)
def _find_recommendation_language(text: str) -> str | None:
return _first_match(text, _RECOMMENDATION_PATTERNS)
def _says_no_records(text: str) -> bool:
return _first_match(text, _NO_RECORDS_PATTERNS) is not None
def _says_not_found(text: str) -> bool:
return _first_match(text, _NOT_FOUND_PATTERNS) is not None
# The time window is full of numbers - dates, times, "rolling 7 days" - and
# stating it is exactly what a good zero-row answer does. Strip it before
# looking for fabricated figures, or the honest answer trips the check.
_WINDOW_NOISE = re.compile(
r"rolling\s+\d+\s+days?|\d{4}-\d{2}-\d{2}(?:[T ]\d{2}:\d{2}(?::\d{2})?)?",
re.IGNORECASE,
)
def _contains_quantity(text: str, ignoring: list[str] | None = None) -> bool:
"""Any bare quantity in a zero-row answer is a fabricated figure.
Tolerates a literal zero - "the query returned 0 rows" is honest - and
tolerates the time window, which the answer is required to state.
"""
for phrase in ignoring or []:
if phrase:
text = text.replace(phrase, " ")
text = _WINDOW_NOISE.sub(" ", text)
for match in _QUANTITY.finditer(text):
token = match.group(0).strip()
if token.split()[0] not in {"0", "0.0", "zero"}:
return True
return False
def _looks_like_a_step_list(text: str) -> bool:
"""Two or more enumerated lines is an action sequence, whoever numbered it.
A single numbered line is usually a clause reference like '4.2' inside a
quoted prerequisite, which is legitimate.
"""
return len(_STEP_LIST.findall(text)) >= 2
def validate_answer(payload: dict[str, Any], klass: QuestionClass) -> BaseAnswer:
"""Validate a generated payload against its class contract.
Raises ContractViolation (never returns a partially-valid object).
"""
model = CONTRACT_FOR[klass]
try:
return model.model_validate(payload)
except ContractViolation:
raise
except Exception as exc: # pydantic ValidationError and anything else
raise ContractViolation(
"schema_invalid",
f"{klass.value} payload did not match its contract: {exc}",
str(payload.get("answer", "")),
) from exc