fix(loop-init): replace retired claude-sonnet-4 identifier in foundry stack

[scemii]

Summary

loop-init --with-foundry scaffolds an implementer stack pinned to claude-sonnet-4-20250514, which Anthropic retired on the Claude API on 15 June 2026. The generated stack.yaml therefore fails on first run. This swaps it for the replacement Anthropic lists for that model, claude-sonnet-4-6.

Changes

• Tool change (tools/loop-init)
• New pattern or starter
• Doc / example improvement
• Story

One line in tools/loop-init/src/cli.ts, in foundryStackYaml()'s model/anthropic interface layer. Nothing else touched.

Note on dist/

tools/loop-init/dist/cli.js is committed and holds the same string, but it is build output from npm run build. I left it untouched rather than hand-editing generated code — it will pick this up on the next build.

Checklist

• No secrets, tokens, internal company URLs
• No other model identifiers changed, no refactoring
• node tools/loop-audit/dist/cli.js . — could not run, see below

Testing

Clean clone, isolated environment:

• tsc --noEmit: clean
• test suite before the change: 59 tests, 58 pass, 1 fail
• test suite after the change: 59 tests, 58 pass, 1 fail, same test

The single failure is pre-existing and unrelated: loop-init prints Loop Ready score after scaffold. npm ci in tools/loop-init cannot resolve @cobusgreyling/loop-audit@^1.8.0 — npm currently publishes up to 1.7.0 — so that test has no audit binary to call, and for the same reason I could not tick the loop-audit checklist item. I ran the suite with TypeScript installed out-of-tree to work around the install failure. That version pin may be worth a separate look.

On sampling parameters: the generated stack sets no temperature, and Sonnet 4.6 sits below the Opus 4.7 threshold where non-default temperature / top_p / top_k are rejected. So this is a plain identifier swap with no change to the request shape.