ADR 0122 — Optional-peer surfaces are proven from artifacts

Context

A source module can be independent of an SDK while its public barrel is not. createToolInvoker uses the canonical contract runner without MCP or AI, but stitchkit/tools also mounts those adapters and resolves their peers at import time. Conversely, the root Socket.IO client keeps its optional peer behind a runtime-selected import, but Webpack warns about that expression even when the consumer supplies the documented literal loader.

Tree-shaking and optional peer metadata do not prove either experience. The published artifact and the consuming bundler decide them.

Decision

• stitchkit/tools/invoker is the peer-free public surface for canonical in-process tool dispatch. stitchkit/tools remains the full adapter barrel.
• The root keeps Socket.IO lazy and optional. Its emitted browser artifact preserves Webpack’s ignore directive on only the runtime-selected fallback; a consumer-provided literal peers.client import remains visible to Webpack.
• A packed minimal consumer invokes a validated contract tool on Bun and Node.
• A packed Next/Webpack client compiles the documented Socket.IO loader and treats the expression-dependency warning as a failure.

Consequences

• Consumers install peers for the adapters they import, not for unrelated mechanics beside them in a barrel.
• There is still one tool runner and one Socket.IO client; entrypoints describe dependency budgets rather than fork behavior.
• Artifact rewrites are count-checked and fail if the emitted shape changes.
• Runtime missing-peer errors and injected-loader behavior remain unchanged.