Explore: Streaming Payments / Payroll

## Summary

**Streaming payments / payroll**: a continuous linear drip that the recipient can withdraw at any time (VestingWallet to Sablier). Payroll, grants, gradual unlocks. A close sibling of Linear Vesting (#3).

**Category:** DeFi

## Status

**To be researched.** This candidate is listed in the [catalog tracker](https://github.com/input-output-hk/contracts-library/issues/16) but has not yet been explored in depth. This issue is a placeholder to collect prior art, use cases, and design questions before a full exploration writeup.

## Why this is a candidate

- **Ecosystem demand:** Steady; payroll, grants, and gradual unlocks are common treasury needs.
- **Reusability:** Overlaps heavily with Linear Vesting (#3) and the Event-Triggered Assets substandard (#28); a key question is whether it is a distinct contract or a configuration of those.

## To research

- Relationship to Linear Vesting (#3) and Event-Triggered Assets (#28): distinct contract or shared mechanism.
- Partial-withdrawal accounting on eUTxO (continuous drip with any-time withdrawal).
- Prior art on Cardano and other ecosystems (Sablier, Superfluid, LlamaPay).
- Audit-tractable scope.

## Exploration deliverables

- [ ] Prior-art survey (Cardano + other ecosystems)
- [ ] Relationship check: Linear Vesting (#3), Event-Triggered Assets (#28)
- [ ] Partial-withdrawal / drip accounting design
- [ ] Lightweight design sketch
- [ ] Composability check against `ARCHITECTURE.md`
- [ ] Recommendation: implement now / later / never (with reason)

Start with the related Linear Vesting (#3), Event-Triggered Assets (#28), catalog tracker (#16), and ARCHITECTURE.md. Survey Cardano and other ecosystems, examine partial-withdrawal accounting and relationships between the candidates, then produce the listed design sketch, composability check, and implement-now/later/never recommendation.

Written by the indexing model from the issue text.