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Android Span Parity Protocol

Android ONNX Runtime Mobile exports must preserve the same tokenization and span decoding behavior as the Python reference. The parity fixture in android/openmedkit/src/test/resources/parity/android_span_parity.json pins that contract for synthetic clinical text.

Generate Fixtures

Export a token-classification checkpoint with the Android ONNX profile, then generate the parity JSON:

.venv/bin/python -m openmed.onnx.convert \
  --model dslim/bert-base-NER \
  --output dist/example-android-onnx \
  --profile android

.venv/bin/python scripts/android/generate_parity_fixtures.py \
  --export-dir dist/example-android-onnx \
  --output android/openmedkit/src/test/resources/parity/android_span_parity.json

The generator validates the ONNX graph with the Android profile, loads the exported tokenizer and id2label.json, runs the ONNX logits output through a deterministic argmax decoder, and writes token IDs, character offsets, predicted labels, and decoded spans.

Fixture Contract

Android parity tests must compare these fields:

  • cases[].text: exact synthetic input text.
  • cases[].tokens[].id: exact tokenizer ID sequence.
  • cases[].tokens[].offset: exact [start, end) character offsets.
  • cases[].spans[].canonical_label: exact canonical label.
  • cases[].spans[].start and cases[].spans[].end: exact span boundaries.

The committed tolerance contract is strict:

{
  "token_ids": "exact",
  "char_offsets": "exact",
  "span_labels": "exact",
  "span_boundaries": {
    "mode": "exact",
    "tolerance_chars": 0
  },
  "logit_ties": "lowest_label_id"
}

If an Android decoder produces the same label but shifts a boundary by one character, the parity test should fail. Boundary tolerance is documented in the fixture so a future change can be reviewed explicitly instead of drifting silently.

Privacy Rules

Parity inputs must remain synthetic. The committed fixture marks each case with synthetic: true and phi_free: true, uses SYNTH_ placeholders, and rejects common PHI-shaped patterns such as emails, phone numbers, and SSNs during Python validation.

Span records do not include surface text. Android tests should slice cases[].text with the expected offsets when they need the span surface, and use text_hash as a deterministic integrity check.

Android Resource Layout

The Android module loads fixtures from:

android/openmedkit/src/test/resources/parity/android_span_parity.json

The resource is plain JSON and has no Android-specific binary encoding. A JVM unit test can read it with the class loader, parse cases, run the Android tokenizer and ONNX session for each text, and compare tokens and spans against the fields listed above.