fix(relay,osv): guard json.loads against JSONDecodeError

[AlexFucuson9]

Problem

Two locations call json.loads() on external input without catching JSONDecodeError:

gateway/relay/descriptor.py:74 — CapabilityDescriptor.from_json()

raw = json.loads(data)           # crashes on malformed JSON
filtered = {k: v for k, v in raw.items() if k in known}  # crashes if raw is not a dict

A malformed handshake message (e.g. JSON array, truncated JSON, or non-JSON payload) causes either JSONDecodeError or AttributeError on .items().

tools/osv_check.py:165 — _query_osv_batch()

with urllib.request.urlopen(req, timeout=_TIMEOUT) as resp:
    result = json.loads(resp.read())  # crashes on non-JSON response

The OSV API can return HTML error pages (rate limit, 502 gateway error), causing the entire vulnerability check to crash instead of gracefully returning no results.

Fix

• descriptor.py: Wrap json.loads() in try/except (json.JSONDecodeError, TypeError), raise ValueError with clear message. Add isinstance(raw, dict) guard before .items().
• osv_check.py: Wrap json.loads() in try/except (json.JSONDecodeError, UnicodeDecodeError), log warning, return empty list.

Impact

• Severity: P1 — crash on malformed external input
• Scope: 2 files, 12 lines added
• Risk: Minimal — only adds error handling

[tonydwb]

Defensive json.loads guards in relay descriptor and OSV check (12 additions, 2 files). Proper error handling for malformed JSON and type validation. Clean and minimal.

Reviewed by Hermes Agent

[teknium1]

Thanks for addressing two real external-input crash paths. The current-main failures reproduce at gateway/relay/descriptor.py:74-76 and tools/osv_check.py:165-167.

Problems

• The OSV patch still permits a crash for valid but non-object JSON: after decoding [], the unchanged result.get("vulns", []) raises AttributeError at tools/osv_check.py:168. Please validate the decoded response is a dict before using it.
• Please add regressions for malformed/non-object descriptor JSON and malformed/non-object OSV response bodies. Current tests in tests/gateway/relay/test_descriptor.py and tests/tools/test_osv_check.py cover valid payloads but not these failure paths.

Suggested changes

• Fail open with a warning when the OSV response is not a JSON object (and validate the vulns shape before filtering).
• Add targeted tests for HTML/malformed bytes and [], then run the two affected test files through scripts/run_tests.sh.

Automated hermes-sweeper review.

[teknium1]

A valid JSON but non-object response such as [] reaches this line and raises AttributeError, so the OSV check is still not fail-open for all malformed/unexpected response shapes. Please return [] when result is not a dict (and consider validating vulns is a list).