pyr0ball
84e0cf5245
- Implements FalsePositiveSuppressor using embedding cosine similarity - Lazy corpus embedding via get_embedder() with module-level cache keyed by db_path - Cache invalidated automatically when the resolved incident corpus changes - Suppresses hypotheses with novelty_score below configurable threshold (default 0.85) - Full fallback path (novelty=1.0, no suppression) when model_id empty, embedding service unavailable, or no resolved incidents found in DB - Graceful handling of missing incidents table and DB query failures - Numpy bool_ leakage prevented by explicit float()/bool() coercion at assignment - Pure-Python cosine fallback for environments without numpy - 9 new tests (all mocked, no real model downloads): passthrough, suppress, no-suppress, empty list, ranking, empty corpus, DB failure, service unavailable, cache invalidation - 350 total tests passing (341 pre-existing + 9 new) Closes: #29
252 lines
9.3 KiB
Python
252 lines
9.3 KiB
Python
"""Stage 4: False-Positive Suppressor — embedding cosine similarity.
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Compares each hypothesis against a corpus of resolved incidents using
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embedding cosine similarity. Hypotheses that closely match a previously
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resolved incident are suppressed as likely false positives.
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When no embedding model is configured or the service is unavailable, all
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hypotheses pass through with novelty_score=1.0 (full novelty assumed).
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"""
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from __future__ import annotations
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import logging
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import sqlite3
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from pathlib import Path
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from typing import Any
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from app.services.diagnose.models import Hypothesis, RankedHypothesis
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logger = logging.getLogger(__name__)
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# Module-level corpus cache: db_path_str -> (corpus_texts, embeddings)
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# Invalidated when the corpus text list changes between calls.
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_corpus_cache: dict[str, tuple[list[str], Any]] = {}
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# ---------------------------------------------------------------------------
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# Cosine similarity helpers
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# ---------------------------------------------------------------------------
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try:
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import numpy as np
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def _cosine_similarities(
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query_emb: list[float], corpus_embs: list[list[float]]
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) -> list[float]:
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"""Batch cosine similarity of one query embedding against all corpus embeddings."""
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q = np.array(query_emb, dtype=np.float32)
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c = np.array(corpus_embs, dtype=np.float32)
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q_norm = q / (np.linalg.norm(q) + 1e-10)
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c_norm = c / (np.linalg.norm(c, axis=1, keepdims=True) + 1e-10)
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return list(c_norm @ q_norm)
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_HAS_NUMPY = True
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except ImportError: # pragma: no cover
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import math
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_HAS_NUMPY = False
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def _dot(a: list[float], b: list[float]) -> float:
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return sum(x * y for x, y in zip(a, b))
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def _norm(a: list[float]) -> float:
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return math.sqrt(sum(x * x for x in a)) + 1e-10
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def _cosine(a: list[float], b: list[float]) -> float:
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return _dot(a, b) / (_norm(a) * _norm(b))
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def _cosine_similarities(
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query_emb: list[float], corpus_embs: list[list[float]]
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) -> list[float]:
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return [_cosine(query_emb, c) for c in corpus_embs]
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# ---------------------------------------------------------------------------
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# DB helpers
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# ---------------------------------------------------------------------------
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def _fetch_resolved_incidents(db_path: Path) -> list[str]:
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"""Fetch resolved incident texts from SQLite.
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Returns a list of non-empty combined strings for each resolved incident.
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Returns an empty list on any error (missing table, connection failure, etc.).
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"""
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try:
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with sqlite3.connect(str(db_path)) as conn:
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cursor = conn.execute(
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"SELECT label, notes FROM incidents WHERE ended_at IS NOT NULL LIMIT 200"
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)
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rows = cursor.fetchall()
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except sqlite3.OperationalError as exc:
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logger.warning("Could not query resolved incidents (%s) — treating as empty corpus", exc)
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return []
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except Exception as exc:
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logger.warning("Unexpected error fetching resolved incidents (%s) — treating as empty corpus", exc)
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return []
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texts: list[str] = []
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for label, notes in rows:
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label = (label or "").strip()
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notes = (notes or "").strip()
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combined = f"{label}. {notes}" if label and notes else (label or notes)
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if combined:
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texts.append(combined)
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return texts
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# ---------------------------------------------------------------------------
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# Public class
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# ---------------------------------------------------------------------------
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class FalsePositiveSuppressor:
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"""Stage 4 of the multi-agent diagnose pipeline.
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Uses embedding cosine similarity to detect hypotheses that closely match
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previously resolved incidents and suppress them as likely false positives.
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When model_id is empty or the embedding service is unavailable, all
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hypotheses pass through with novelty_score=1.0 (no suppression).
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"""
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def __init__(
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self,
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model_id: str = "",
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device: str = "cpu",
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suppress_threshold: float = 0.85,
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) -> None:
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self._model_id = model_id
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self._device = device
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self._suppress_threshold = suppress_threshold
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def suppress(
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self,
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hypotheses: list[Hypothesis],
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db_path: Path,
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) -> list[RankedHypothesis]:
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"""Rank hypotheses by novelty, suppressing those matching resolved incidents.
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Args:
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hypotheses: Candidate hypotheses from Stage 3.
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db_path: Path to the Turnstone SQLite database containing incidents.
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Returns:
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List of RankedHypothesis sorted by (novelty_score * confidence) descending.
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Non-suppressed hypotheses appear first in practice.
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"""
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if not hypotheses:
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return []
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# No model configured — full passthrough, rank by confidence only.
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if not self._model_id:
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return self._passthrough(hypotheses)
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# Attempt to obtain an embedder; fall back to passthrough on failure.
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embedder = self._load_embedder()
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if embedder is None:
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logger.warning(
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"Embedding service unavailable for model %r — skipping suppression",
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self._model_id,
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)
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return self._passthrough(hypotheses)
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# Fetch corpus texts from DB; fall back to passthrough if corpus is empty.
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corpus_texts = _fetch_resolved_incidents(db_path)
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if not corpus_texts:
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logger.debug("No resolved incidents found — all hypotheses treated as novel")
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return self._passthrough(hypotheses)
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# Embed corpus (with caching).
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corpus_embeddings = self._get_corpus_embeddings(embedder, corpus_texts, db_path)
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# Rank hypotheses using novelty score.
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ranked: list[RankedHypothesis] = []
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for h in hypotheses:
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h_text = f"{h.title}. {h.description}"
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try:
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h_emb = embedder.embed(h_text)
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# Convert numpy array to plain Python list for _cosine_similarities
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h_emb_list: list[float] = h_emb.tolist() if hasattr(h_emb, "tolist") else list(h_emb)
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sims = _cosine_similarities(h_emb_list, corpus_embeddings)
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max_sim = max(sims) if sims else 0.0
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except Exception as exc:
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logger.warning("Embedding failed for hypothesis %r: %s — treating as novel", h.title, exc)
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max_sim = 0.0
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max_sim = float(max_sim)
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novelty_score = 1.0 - max_sim
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suppress = bool(novelty_score < self._suppress_threshold)
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suppression_reason = (
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f"Similar to resolved incident (similarity {max_sim:.2f})"
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if suppress
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else None
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)
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ranked.append(
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RankedHypothesis(
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hypothesis=h,
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novelty_score=novelty_score,
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similarity_to_known=max_sim,
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suppress=suppress,
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suppression_reason=suppression_reason,
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)
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)
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ranked.sort(key=lambda rh: rh.novelty_score * rh.hypothesis.confidence, reverse=True)
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return ranked
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# ------------------------------------------------------------------
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# Private helpers
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# ------------------------------------------------------------------
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def _load_embedder(self) -> Any | None:
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"""Load the embedding service. Returns None if unavailable."""
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try:
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from app.services.embeddings import get_embedder
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return get_embedder()
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except Exception as exc:
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logger.warning("Failed to import/initialise embedding service: %s", exc)
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return None
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def _get_corpus_embeddings(
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self,
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embedder: Any,
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corpus_texts: list[str],
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db_path: Path,
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) -> list[list[float]]:
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"""Return cached corpus embeddings, re-embedding if the corpus has changed."""
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cache_key = str(db_path)
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cached = _corpus_cache.get(cache_key)
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if cached is not None:
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cached_texts, cached_embeddings = cached
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if cached_texts == corpus_texts:
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return cached_embeddings
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logger.debug("Embedding corpus of %d resolved incidents", len(corpus_texts))
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try:
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raw_embeddings = embedder.embed_batch(corpus_texts)
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# Normalise each embedding to a plain Python list for portability
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corpus_embeddings: list[list[float]] = [
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e.tolist() if hasattr(e, "tolist") else list(e)
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for e in raw_embeddings
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]
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except Exception as exc:
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logger.warning("Corpus embedding failed: %s — treating as empty corpus", exc)
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return []
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_corpus_cache[cache_key] = (corpus_texts, corpus_embeddings)
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return corpus_embeddings
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def _passthrough(self, hypotheses: list[Hypothesis]) -> list[RankedHypothesis]:
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"""Return all hypotheses as non-suppressed, ranked by confidence descending."""
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ranked = [
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RankedHypothesis(
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hypothesis=h,
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novelty_score=1.0,
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similarity_to_known=0.0,
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suppress=False,
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suppression_reason=None,
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)
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for h in hypotheses
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]
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ranked.sort(key=lambda rh: rh.hypothesis.confidence, reverse=True)
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return ranked
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