Review Sensitive Data Before AI
A browser-extension prototype that checks pasted text locally using narrow rules and a compact MiniLM detector.
Review every candidate, choose Mask or Keep, then insert the reviewed text into a trusted AI destination.
Preview-first because the measured automatic-masking precision did not meet the 98% release gate.
Detect exact spans
MiniLM handles contextual spans
Rules handle narrow URLs and secrets
Review before masking
Every candidate appears in a preview
You decide what to Mask or Keep
Preserve the question
Remove incidental private detail
Keep public context needed for the answer
How it works
| Step | What happens |
|---|---|
| Paste interception | The extension listens for text pasted into an allowlisted editor. |
| Local analysis | Packaged MiniLM INT8, tokenizer, ONNX Runtime Web WASM, and deterministic rules run locally. |
| Exact reconstruction | BIOES decoding returns candidates to their original character offsets, including overlapping long-text windows. |
| User preview | Each candidate stays behind Mask or Keep review; the extension does not silently rewrite the prompt. |
| Reviewed insertion | The selected result is inserted into the same editor. Cancellation makes no change. |
| Failure behavior | If the scanner, model, or WASM fails, the original paste is restored so user work is not blocked. That failed paste is not protected. |
Measured evidence
| Result | Evidence boundary |
|---|---|
| 0.886 exact-span F1 | MiniLM hybrid on a frozen 1,000-case synthetic/public detector test. |
| 95.8% auto-mask precision | Below the provisional 98% gate, so preview review remains mandatory. |
| About 196 ms warm p95 | Controlled 1K-character paste in retained Brave measurements on the development Mac. |
| 31 runtime tests | Plus retained browser evidence for normal, corrupt-model, missing-WASM, and unsupported-WebAssembly cases. |
Read the frozen baseline, policy regression, runtime benchmark, and security audit.
Preserve useful context
Original prompt
My cousin Ananya studies at DPS Indiranagar. Is that school any good?
Reviewed prompt
My cousin [PERSON] studies at DPS Indiranagar. Is that school any good?
The private name is unnecessary. The school is the query anchor and remains available to the AI tool.
