A test pins MCP `propose_to_parent_forge` when the parent cannot be reached: `parent_unreachable`, and nothing is proposed #7176

src/http/mcp/tools/propose_to_parent_forge.ts answers parent_unreachable ("parent unreachable: nothing was proposed") when the parent forge does not answer, and no test names it.

Done:

• [ ] A new test links a child forge to a stub parent that refuses connections, then calls the tool through /mcp as a writer. The answer is parent_unreachable in those words.
• [ ] Nothing is recorded as proposed, and a retry once the stub answers proposes exactly once.
• [ ] A reader gets the write-access refusal before any request is made to the parent.

Files: test/mcp-parent-unreachable.test.ts

If the test finds the behaviour wrong, fix the module it names in the same pull and say so. If the check fails in a test this pull does not touch, name it in the pull rather than widening the change.

Before pushing: bun x tsc --noEmit and the new test.