# Sprint 81 Plan: Plugin Ecosystem for Language and Runtime Packs

## Context

Core velocity improves when third-party teams can ship adapters and runtime packs
without forking the platform. Sprint 81 introduces a governed plugin ecosystem.

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## Goals

1. Define plugin SDK for language adapters and runtime semantics packs
2. Support signed plugin loading with compatibility checks
3. Add plugin certification path before production enablement
4. Prevent unsafe plugin behavior via sandbox and policy controls

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## Steps

### Step 1039: Plugin SDK schema (`adapter`, `runtime_pack`, `verifier`) (12 tests)
### Step 1040: Plugin manifest and capability declaration model (10 tests)
### Step 1041: Signed plugin package verification pipeline (10 tests)
### Step 1042: Plugin compatibility resolver (core/API/version) (10 tests)
### Step 1043: Plugin sandbox execution policy (10 tests)
### Step 1044: Plugin certification workflow integration (8 tests)
### Step 1045: `whetstone_list_plugins` MCP tool (8 tests)
### Step 1046: `whetstone_install_or_disable_plugin` MCP tool (8 tests)
### Step 1047: Plugin trust and risk report artifact (8 tests)
### Step 1048: Sprint 81 integration summary + regression (8 tests)

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## Safety Rule

- Unsigned or uncertified plugins cannot run in Stable-tier pathways.