> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rotavision.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Silent-change detection

> Sakshi fingerprints each agent's behaviour from the witnessed decision stream and tells you the day it started behaving differently — and whether the change was declared or silent. Maps to the RBI unauthorised-change obligation.

Agents change silently. A model gets swapped underneath one, a prompt is
injected, data drifts — and nobody notices until it is a headline. Silent-change
detection fingerprints each agent's behaviour from the decision chain and tells
you the day it started behaving differently, with **no new system of record** and
**no GPU** — just statistics over evidence you already have.

## The behavioural fingerprint

Sakshi computes a fingerprint per agent from its witnessed decisions — the model
serving it, its decision and routing mix, its tool use, its decline reasons — and
measures how far a recent window has diverged from the window before it. A
dimension is only flagged when the shift is both large **and** statistically
significant, so a quiet agent never cries wolf (the same discipline as the
Vishwas fairness screen and the evaluation confidence intervals).

```bash theme={null}
# fleet summary — changed agents first
GET /api/v1/behavior/fleet

# per-agent: which dimensions diverged, baseline vs current
GET /api/v1/behavior/agents/{agent_id}/change
```

## Declared vs silent

A flagged change is only alarming if it was **undeclared**. Sakshi correlates each
flagged dimension with the governance events that would explain it — a model
registered in the agent's provenance, an autonomy envelope published — and
classifies the change:

* **declared** — every flagged dimension is explained by a governance act you took
  (a registered model, a published policy). Expected; no alarm.
* **silent** — a flagged dimension has no governance event to explain it. The agent
  changed and nobody declared why.

A declared model upgrade and a silent swap look identical in the metrics; the
difference is whether you told the registry — and Sakshi checks.

## The signed change report

Persisting a report Ed25519-signs the verdict as a tamper-evident,
RBI-mapped artifact (the unauthorised-change obligation). When the verdict is
**silent**, the report also emits an `agent_behavior_changed` webhook and flags
the agent for [re-certification](/concepts/certification) — so a silent change
automatically sends the agent back through the fit-for-production gate.

```bash theme={null}
# persist a signed change report (silent -> flags re-cert + emits a webhook)
POST /api/v1/behavior/agents/{agent_id}/report
GET  /api/v1/behavior/reports/{id}/export   # the signed artifact
```