# Agent Session Continuity

> Agent Session Continuity is a paid API for AI agents from phion.systems, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-20).

Verifies hash-linked session identity and monotonic sequence continuity for AI agent sessions

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/agent-session-continuity?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-session-continuity-bf03bb88
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XFg89O2ddZYGW_-57zaHy

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agent-session-continuity-bf03bb88 -d '<json body>'
```

Example prompt: Before we continue with this multi-step transaction, verify that our current session hash and sequence number are still properly linked and haven't been tampered with or reordered.

## When to prefer this

Choose this endpoint when an AI agent needs cryptographic assurance that its session chain has not been tampered with, reordered, or replayed — particularly before executing payments, sensitive operations, or multi-step workflows where session integrity is critical. Prefer this over generic authentication checks when hash-linked continuity and monotonic sequence validation are specifically needed.

## Known failure modes

- Hash mismatch indicating session tampering or corruption
- Non-monotonic sequence number detecting dropped or reordered messages
- Missing or malformed session identity input
- Session chain break detected between prior and current state
- Invalid or expired session reference
- Malformed request payload with missing required fields

## How this service works

Verify hash-linked session identity and monotonic sequence continuity

## Output

A verification result indicating whether the session's hash linkage is valid and the sequence number is monotonically continuous, including any detected anomalies such as gaps, reversals, or hash mismatches in the session chain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "example"
   ],
   "properties": {
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-session-continuity-bf03bb88/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)