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brain-of-reese/tests/unit/test_chat_gate.py
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"""Unit: the honesty gate (A8) — boundary, prompts, and suggestion chips.
Pure gate logic runs against fake retriever output (``RetrievedChunk``
rows from a fake retriever) with no Postgres and no network. The
endpoint-level tests drive ``POST /api/chat`` with the retriever, the DB
session, and the LLM all faked, so the whole deflection contract
(prompt → deltas → done event → query_log) is verified without a stack.
"""
from __future__ import annotations
import json
import uuid
from collections.abc import Iterator
from typing import Any
import pytest
from fastapi.testclient import TestClient
from app.api import chat as chat_api
from app.config import Settings
from app.main import app as fastapi_app
from app.models import Document, QueryLog
from app.rag.retriever import RetrievedChunk, weak_hit_titles
from app.rag.suggestions import MAX_SUGGESTIONS, derive_suggestions
ANSWER = "I haven't done anything like that — try one of these instead!"
def _settings(threshold: float = 0.30) -> Settings:
return Settings(
_env_file=None, # pyright: ignore[reportCallIssue]
relevance_threshold=threshold,
)
def _doc(title: str, content: str) -> Document:
return Document(
id=uuid.uuid4(),
source="Homelab",
path=f"{title.lower().replace(' ', '-')}.md",
full_path="/tmp/doc.md",
title=title,
content=content,
content_hash="0" * 64,
)
def _chunk(
doc: Document, score: float, cosine: float | None = None, fts_hit: bool = False
) -> RetrievedChunk:
"""Fake candidate: *score* is the fused rank score; *cosine* (defaults to
*score*) is the vector-similarity gate input."""
return RetrievedChunk(
chunk_id=uuid.uuid4(),
position=0,
content=doc.content[:32],
score=score,
document=doc,
cosine=score if cosine is None else cosine,
fts_hit=fts_hit,
)
# ---------- gate boundary (fake retriever rows, no LLM) ----------
def test_gate_boundary_score_at_threshold_answers() -> None:
"""Score exactly at the threshold ⇒ HIGH (the gate is strict <)."""
doc = _doc("Kubernetes Homelab Cluster", "TALOS_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(doc, 0.30)], _settings(threshold=0.30))
assert plan.deflected is False
assert plan.top_score == pytest.approx(0.30)
assert "<relevance>HIGH</relevance>" in plan.system_prompt
assert "DEFLECT_MODE" not in plan.system_prompt
assert "TALOS_DOC_CONTENT" in plan.system_prompt
assert plan.suggestions == []
def test_gate_boundary_just_below_threshold_deflects() -> None:
doc = _doc("Kubernetes Homelab Cluster", "TALOS_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(doc, 0.2999)], _settings(threshold=0.30))
assert plan.deflected is True
assert plan.top_score == pytest.approx(0.2999)
assert "<relevance>LOW</relevance>" in plan.system_prompt
assert "DEFLECT_MODE" in plan.system_prompt
# Titles only: the full document content must never reach the LLM.
assert "TALOS_DOC_CONTENT" not in plan.system_prompt
assert "Kubernetes Homelab Cluster" in plan.system_prompt
def test_gate_is_env_tunable_via_settings() -> None:
doc = _doc("Backup Strategy", "BACKUP_DOC_CONTENT")
hits = [_chunk(doc, 0.30)]
assert chat_api.plan_turn(hits, _settings(threshold=0.35)).deflected is True
assert chat_api.plan_turn(hits, _settings(threshold=0.25)).deflected is False
# ---------- hybrid gate matrix (A8, revised: cosine AND fts) ----------
def test_gate_weak_cosine_with_fts_hit_still_answers() -> None:
"""cosine < threshold but a lexical hit ⇒ HIGH — the FTS-OR branch.
This is the name-your-tool case: "kafkabridge" grounds despite weak
vector overlap."""
doc = _doc("Static DNS", "DNS_DOC_CONTENT")
plan = chat_api.plan_turn(
[_chunk(doc, 0.02, cosine=0.10, fts_hit=True)], _settings(threshold=0.30)
)
assert plan.deflected is False
assert plan.top_score == pytest.approx(0.10) # gate input is the cosine
assert plan.fts_hits == 1
assert "DNS_DOC_CONTENT" in plan.system_prompt
assert plan.suggestions == []
def test_gate_weak_cosine_zero_fts_deflects() -> None:
doc = _doc("Kubernetes Homelab Cluster", "TALOS_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(doc, 0.02, cosine=0.10)], _settings(threshold=0.30))
assert plan.deflected is True
assert plan.top_score == pytest.approx(0.10)
assert plan.fts_hits == 0
def test_gate_strong_cosine_without_fts_answers() -> None:
doc = _doc("Kubernetes Homelab Cluster", "TALOS_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(doc, 0.90, cosine=0.90)], _settings(threshold=0.30))
assert plan.deflected is False
assert plan.fts_hits == 0
def test_gate_fts_hits_counts_all_lexical_candidates() -> None:
a = _doc("Alpha", "ALPHA_CONTENT")
b = _doc("Beta", "BETA_CONTENT")
chunks = [
_chunk(a, 0.03, cosine=0.05, fts_hit=True),
_chunk(a, 0.02, cosine=0.04, fts_hit=True), # same doc, second chunk
_chunk(b, 0.01, cosine=0.03),
]
plan = chat_api.plan_turn(chunks, _settings(threshold=0.30))
assert plan.deflected is False
assert plan.fts_hits == 2 # per chunk, not per doc
def test_gate_lexical_only_chunk_does_not_inflate_cosine() -> None:
"""top_score stays the best *vector* cosine even when a lexical-only
chunk (cosine 0.0 by construction) carries the highest fused score."""
a = _doc("Alpha", "ALPHA_CONTENT")
b = _doc("Beta", "BETA_CONTENT")
chunks = [
_chunk(a, 0.50, cosine=0.55), # vector rank 1
_chunk(b, 0.90, cosine=0.0, fts_hit=True), # lexical rank 1 wins the ranking
]
plan = chat_api.plan_turn(chunks, _settings(threshold=0.30))
assert plan.top_score == pytest.approx(0.55)
assert plan.deflected is False # 0.55 >= 0.30 anyway
# ranking follows the fused score: Beta's doc is the top source
assert plan.docs[0].title == "Beta"
def test_gate_zero_chunks_deflects_with_fallback_chips() -> None:
plan = chat_api.plan_turn([], _settings())
assert plan.deflected is True
assert plan.top_score == 0.0
assert "nothing close at all" in plan.system_prompt
# No weak hits ⇒ onboarding fallback fills the chips.
assert 2 <= len(plan.suggestions) <= MAX_SUGGESTIONS
# ---------- prompt content (LOW vs HIGH) ----------
def test_low_prompt_has_titles_only_no_content() -> None:
a = _doc("Kubernetes Homelab Cluster", "ALPHA_DOC_CONTENT")
b = _doc("Backup Strategy", "BETA_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(b, 0.10), _chunk(a, 0.20)], _settings())
prompt = plan.system_prompt
assert "<relevance>LOW</relevance>" in prompt
assert "DEFLECT_MODE" in prompt
assert "HONESTY GATE" in prompt # the LOW rule is what the model follows
assert "- Kubernetes Homelab Cluster" in prompt
assert "- Backup Strategy" in prompt
assert "ALPHA_DOC_CONTENT" not in prompt
assert "BETA_DOC_CONTENT" not in prompt
assert "<documents>" not in prompt
def test_high_path_unaffected() -> None:
a = _doc("Kubernetes Homelab Cluster", "ALPHA_DOC_CONTENT")
b = _doc("Backup Strategy", "BETA_DOC_CONTENT")
plan = chat_api.plan_turn([_chunk(a, 0.90), _chunk(b, 0.40)], _settings())
assert plan.deflected is False
assert plan.suggestions == []
assert "<relevance>HIGH</relevance>" in plan.system_prompt
assert "DEFLECT_MODE" not in plan.system_prompt
assert "ALPHA_DOC_CONTENT" in plan.system_prompt
assert "BETA_DOC_CONTENT" in plan.system_prompt
assert [d.title for d in plan.docs] == ["Kubernetes Homelab Cluster", "Backup Strategy"]
# ---------- weak_hit_titles (fake retriever mapping) ----------
def test_weak_hit_titles_dedupe_and_rank_by_best_score() -> None:
a = _doc("Kubernetes Homelab Cluster", "AAA")
b = _doc("Backup Strategy", "BBB")
chunks = [_chunk(b, 0.5), _chunk(a, 0.2), _chunk(a, 0.9)]
assert weak_hit_titles(chunks) == ["Kubernetes Homelab Cluster", "Backup Strategy"]
# ---------- suggestions derivation ----------
def test_suggestions_derived_from_titles_in_order() -> None:
got = derive_suggestions(
["Kubernetes Homelab Cluster", "Backup Strategy", "Deploying a New Service"],
fallback=["should not appear"],
)
assert len(got) == 3
assert all(s.strip() for s in got)
assert "Kubernetes Homelab Cluster" in got[0]
assert "Backup Strategy" in got[1]
assert "Deploying a New Service" in got[2]
def test_suggestions_capped_at_three() -> None:
got = derive_suggestions([f"Title {i}" for i in range(6)], fallback=["F"])
assert len(got) == MAX_SUGGESTIONS == 3
def test_suggestions_top_up_from_fallback_when_titles_thin() -> None:
got = derive_suggestions(
["Backup Strategy"],
fallback=["How is my Kubernetes cluster set up?", "What's my backup strategy?"],
)
assert len(got) == 3
assert got[0] == "What's in your notes about Backup Strategy?"
assert got[1] == "How is my Kubernetes cluster set up?"
def test_suggestions_dedupes_and_ignores_blank() -> None:
got = derive_suggestions(
["Backup Strategy", "backup strategy", " "],
fallback=["What's my backup strategy?", " "],
)
# "backup strategy" is a case-insensitive dup; blank title/fallback are
# skipped — including ones that only look blank after formatting. Only
# two valid items remain, and the list never pads with junk.
assert got == [
"What's in your notes about Backup Strategy?",
"What's my backup strategy?",
]
assert all("about ?" not in s and s == s.strip() for s in got)
def test_suggestions_empty_input_yields_fallback_only() -> None:
assert derive_suggestions([], fallback=[]) == []
got = derive_suggestions([], fallback=["One?", "Two?"])
assert got == ["One?", "Two?"]
# ---------- endpoint-level gate (fake retriever + fake LLM + fake session) ----------
class _CannedLLM:
"""Records the messages it is given; streams a canned answer."""
def __init__(self, answer: str = ANSWER) -> None:
self.settings = Settings(_env_file=None) # pyright: ignore[reportCallIssue]
self.embed_batches = 0
self.answer = answer
self.seen: list[list[dict[str, str]]] = []
async def embed_one(self, _text: str) -> list[float]:
return [0.0] * 768
async def chat_stream(self, messages: list[dict[str, str]]):
self.seen.append(messages)
for i in range(0, len(self.answer), 12):
yield self.answer[i : i + 12]
class _FakeSteeringResult:
"""Empty steering-note result (no stored notes in these unit tests)."""
def all(self) -> list[Any]:
return []
class _FakeSession:
"""Stands in for the DB session: records the QueryLog row it is given.
``scalars`` always yields no steering notes (phase 15) so the chat
turn's ``load_steering_notes`` call stays a no-op here.
"""
def __init__(self) -> None:
self.added: list[Any] = []
self.commits = 0
def add(self, obj: Any) -> None:
self.added.append(obj)
def commit(self) -> None:
self.commits += 1
def scalars(self, _stmt: Any) -> _FakeSteeringResult:
return _FakeSteeringResult()
@pytest.fixture()
def gate_env(monkeypatch: pytest.MonkeyPatch) -> Iterator[tuple[_FakeSession, _CannedLLM]]:
"""``POST /api/chat`` with retriever, session, and LLM all faked."""
monkeypatch.setattr(chat_api, "db_available", lambda: True)
session = _FakeSession()
llm = _CannedLLM()
monkeypatch.setitem(fastapi_app.dependency_overrides, chat_api.get_db, lambda: session)
monkeypatch.setitem(fastapi_app.dependency_overrides, chat_api.get_llm, lambda: llm)
# These tests assert against a specific gate threshold; keep it stable
# regardless of the production default (0.62) or any .env.
monkeypatch.setattr(
chat_api,
"get_settings",
lambda: Settings(_env_file=None, relevance_threshold=0.30), # pyright: ignore[reportCallIssue]
)
yield session, llm
fastapi_app.dependency_overrides.clear()
def _ask(client: TestClient, message: str) -> list[dict[str, Any]]:
with client.stream("POST", "/api/chat", json={"message": message}) as r:
assert r.status_code == 200
frames: list[dict[str, Any]] = []
buf = ""
for part in r.iter_text():
buf += part
while "\n\n" in buf:
frame, buf = buf.split("\n\n", 1)
frame = frame.strip()
if frame.startswith("data:"):
frames.append(json.loads(frame.removeprefix("data:").strip()))
assert buf.strip() == ""
return frames
def _fake_retriever(chunks: list[RetrievedChunk]) -> Any:
def retrieve(_db: Any, _question: str, _vec: list[float]) -> list[RetrievedChunk]:
return chunks
return retrieve
def test_endpoint_just_below_threshold_deflects(
client: TestClient,
gate_env: tuple[_FakeSession, _CannedLLM],
monkeypatch: pytest.MonkeyPatch,
) -> None:
session, llm = gate_env
doc = _doc("Deploying a New Service", "DOC_CONTENT_NEVER_SENT")
monkeypatch.setattr(chat_api, "retrieve", _fake_retriever([_chunk(doc, 0.2999)]))
frames = _ask(client, "How do I bake sourdough bread?")
deltas = [f for f in frames if f["type"] == "delta"]
assert "".join(d["text"] for d in deltas) == ANSWER # the LLM was still called
done = frames[-1]
assert done["type"] == "done"
assert done["deflected"] is True
assert 2 <= len(done["suggestions"]) <= MAX_SUGGESTIONS # title chip + fallback
assert all(s.strip() for s in done["suggestions"])
assert any("Deploying a New Service" in s for s in done["suggestions"])
# The LLM saw the LOW prompt: DEFLECT_MODE + titles, never doc content.
(system, user) = llm.seen[0][0], llm.seen[0][1]
assert user["content"] == "How do I bake sourdough bread?"
assert "DEFLECT_MODE" in system["content"]
assert "DOC_CONTENT_NEVER_SENT" not in system["content"]
# Durable record: deflected + the weak score.
(row,) = session.added
assert isinstance(row, QueryLog)
assert row.deflected is True
assert row.top_score == pytest.approx(0.2999)
assert session.commits == 1
def test_endpoint_score_at_threshold_answers(
client: TestClient,
gate_env: tuple[_FakeSession, _CannedLLM],
monkeypatch: pytest.MonkeyPatch,
) -> None:
session, llm = gate_env
doc = _doc("Kubernetes Homelab Cluster", "TALOS_DOC_SENT")
monkeypatch.setattr(chat_api, "retrieve", _fake_retriever([_chunk(doc, 0.30)]))
frames = _ask(client, "How is my Kubernetes cluster set up?")
done = frames[-1]
assert done["type"] == "done"
assert done["deflected"] is False
assert done["suggestions"] == []
assert done["sources"] and done["sources"][0]["title"] == "Kubernetes Homelab Cluster"
(system, _user) = llm.seen[0][0], llm.seen[0][1]
assert "<relevance>HIGH</relevance>" in system["content"]
assert "DEFLECT_MODE" not in system["content"]
assert "TALOS_DOC_SENT" in system["content"]
(row,) = session.added
assert isinstance(row, QueryLog)
assert row.deflected is False
assert row.top_score == pytest.approx(0.30)