[harsh21234i]

Summary

• Reject non-object values in the top-level format.json before accessing its fields.
• Return a clear invalid-input error and exit code 2 instead of an AttributeError traceback.
• Add regression coverage for null, arrays, strings, and numbers.

Why

Valid JSON does not necessarily contain a valid snapshot marker. Previously, a non-object root caused hflow verify snapshot to crash with an unhandled exception.

Validation

• uv run pytest -q -n 4 — 2,615 passed, 8 skipped
• uv run pytest -q tests/test_snapshot_verify.py — 41 passed
• uv run ruff check — passed
• uv run ruff format --check — passed
• uv run ty check — passed

Closes #746

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[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge.

Summary

Rejects non-object roots in format.json before accessing marker fields.

• Snapshot verification rejects non-object format markers cleanly.

_{Reviews (1) · Last reviewed commit: "fix(snapshot): reject non-object format ..." · Reviewed by Greptile}

[kstonekuan]

Thanks for the fix. Ruff, ty, the snapshot regressions, and both Python CI jobs pass. Merging.