# Claim Check pattern (Azure Architecture Center)

## Metadata

| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | background-work-limits |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | Claim Check pattern (Azure Architecture Center) |
| Source URL | https://learn.microsoft.com/azure/architecture/patterns/claim-check |
| Source publisher / author | Microsoft |
| Source type | vendor docs |
| Source date (published) | 2026-08-31 |
| Date researched | 2026-10-25 |
| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
| Research method | direct page fetch |
| Confidence | High |
| Status | Active |

## Summary

The claim-check cloud design pattern: store a large payload externally and pass only a reference through the messaging system.

## Key findings

- The sender writes the payload to an external store and sends a reference (the claim check); receivers fetch it when they need it; the messaging system never carries the payload.
- Apply it conditionally by size so small messages skip the extra hop; the schema must say whether a payload is inline or external.
- Define who owns payload deletion and coordinate retention with message expiry so a valid token never points at deleted data.
- Do not embed security tokens in the claim check; publish the token only after the payload write succeeded; deliveries can repeat so consumers must be idempotent.
- Include a content hash when consumers must verify integrity; the store must stay available as long as consumers need the payload; retrieval adds latency.
- Alternatives: compress, or split and aggregate the payload.

## Pros / strengths

A named, widely recognized pattern with the failure modes (orphans, dangling tokens, retention) spelled out.

## Cons / limitations / caveats

Written for message brokers; tai's 'broker' is the model context, but the economics (size limits, cost, degraded throughput) are the same.

## Relevance to tai

Names what tai's spill path already is: a long result is stored as a record and the conversation gets a key plus a head and tail summary (`spilled_view`). Confirms the conditional rule (only above `SPILL_LIMIT`) and the write-before-reference order. Retention of agent output records is the open point.

## Changelog

| Date | Change |
|---|---|
| 2026-10-25 | Initial dossier created. |