tegwick
2621cf2752
Assistant: codex Assistant-Model: gpt-6-astra Assistant-Session: 01a07ff8-19d0-7820-b4d0-1353833cb7fc
109 lines
4.8 KiB
Python
109 lines
4.8 KiB
Python
"""Read-only hosted discovery with explicit, bounded source acceptance."""
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from __future__ import annotations
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import hashlib
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import json
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import math
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import urllib.error
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import urllib.parse
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import urllib.request
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from datetime import date, datetime, timedelta, timezone
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from typing import Any
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MAX_SNAPSHOT_BYTES = 5 * 1024 * 1024
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class SnapshotUnavailable(ValueError):
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"""The selected source cannot support a planning recommendation."""
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def load_hosted_snapshot(
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base_url: str, *, max_age_hours: float = 24
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) -> tuple[list[dict[str, Any]], str, dict[str, Any]]:
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"""Fetch the public index; never send intent, tokens or mutation requests.
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Acceptance concerns the hub's composition and warning signals. It does not
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certify that every upstream repository has published its latest capability.
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Failure must not become a local fallback or a 'new capability' verdict.
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"""
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url = base_url.rstrip("/") + "/v1/federated"
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try:
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parsed = urllib.parse.urlsplit(base_url)
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valid_url = (parsed.scheme in {"http", "https"} and parsed.hostname
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and not parsed.username and not parsed.password
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and not parsed.query and not parsed.fragment)
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except ValueError:
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valid_url = False
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if not valid_url:
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raise SnapshotUnavailable("hub URL must be HTTP(S), without credentials, query or fragment")
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if not math.isfinite(max_age_hours) or max_age_hours <= 0:
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raise SnapshotUnavailable("maximum index age must be a positive finite number of hours")
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request = urllib.request.Request(
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url, headers={"Accept": "application/json", "User-Agent": "reuse-surface/0.1"}
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)
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try:
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with urllib.request.urlopen(request, timeout=30) as response:
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if response.status != 200:
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raise SnapshotUnavailable(f"hosted index returned HTTP {response.status}")
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if response.headers.get("X-Federation-Warnings"):
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raise SnapshotUnavailable("hosted index reports federation warnings; inspect its sources")
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raw = response.read(MAX_SNAPSHOT_BYTES + 1)
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except urllib.error.HTTPError as exc:
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raise SnapshotUnavailable(f"hosted index returned HTTP {exc.code}") from exc
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except (urllib.error.URLError, OSError, ValueError) as exc:
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if isinstance(exc, SnapshotUnavailable):
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raise
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raise SnapshotUnavailable("hosted index could not be fetched; no local fallback used") from exc
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if len(raw) > MAX_SNAPSHOT_BYTES:
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raise SnapshotUnavailable("hosted index exceeds the 5 MiB response limit")
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try:
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payload = json.loads(raw)
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except (ValueError, UnicodeError) as exc:
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raise SnapshotUnavailable("hosted index is not valid JSON") from exc
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if not isinstance(payload, dict) or payload.get("stale") is not False:
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raise SnapshotUnavailable("hosted index is stale or its freshness signal is missing")
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now = datetime.now(timezone.utc)
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try:
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composed = datetime.fromisoformat(payload["composed_at"])
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updated = payload["updated"]
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date.fromisoformat(updated)
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if composed.tzinfo is None:
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raise ValueError("timezone missing")
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except (KeyError, TypeError, ValueError) as exc:
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raise SnapshotUnavailable("hosted index has invalid composition metadata") from exc
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age = (now - composed).total_seconds()
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if age < -timedelta(minutes=5).total_seconds() or age > max_age_hours * 3600:
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raise SnapshotUnavailable("hosted index composition is outside the accepted age window")
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capabilities = payload.get("capabilities")
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if not isinstance(capabilities, list) or not capabilities:
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raise SnapshotUnavailable("hosted index has no usable capability collection")
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ids: set[str] = set()
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for item in capabilities:
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if (not isinstance(item, dict)
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or not isinstance(item.get("id"), str) or not item["id"].strip()
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or item["id"] in ids
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or not isinstance(item.get("name"), str)
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or not isinstance(item.get("summary"), str)
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or not isinstance(item.get("tags", []), list)
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or any(not isinstance(tag, str) for tag in item.get("tags", []))
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or any(item.get(key) is not None and not isinstance(item[key], str)
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for key in ("owner", "vector"))):
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raise SnapshotUnavailable("hosted index contains malformed or duplicate capabilities")
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ids.add(item["id"])
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provenance = {
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"kind": "hosted",
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"url": url,
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"fetched_at": now.isoformat(),
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"composed_at": payload["composed_at"],
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"capability_count": len(capabilities),
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"sha256": hashlib.sha256(raw).hexdigest(),
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"digest_format": "response-bytes",
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"max_age_hours": max_age_hours,
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"stale": False,
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"federation_warnings": False,
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}
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return capabilities, updated, provenance
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