Closes#1795.
Enforce localhost-only binding in code (the "never 0.0.0.0" rule was only a spec note): refuse an all-interfaces HOST — across every spelling the OS binds as the wildcard (inet_aton decimal/octal/hex, IPv6, IPv4-mapped, zone-scoped, IDNA/Unicode) — unless DANGEROUSLY_BIND_ALL_INTERFACES=true (Docker's sanctioned opt-in). Fixes the reported stdio-connect 403 by expanding the default loopback origin allow-list to all three interchangeable forms.
Hardening surfaced across an extended review: closes an IDNA/fullwidth wildcard bypass, a blank-ALLOWED_ORIGINS fail-open, and the CLI/TUI OAuth-callback wildcard bind (loopback-only now, RFC 8252); canonicalizes the origin allow-list the way a browser does; derives frame-ancestors from the real embedder list (IPv6-literal exclusion verified in headless Chromium); strictPort on all three bind points; and preserves the CLI exit-code map + JSON envelope through the mcp-inspector --cli launcher path. Shared host normalization lives in core/node/hostUrl.ts. Docs + tests + smokes throughout.
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Most tests import runCli()in-process (see helpers/cli-runner.ts) so
clients/cli/src is measured under the coverage gate. Suite-wide
helpers/mock-open-url.ts (vitest setupFiles) mocks open-url so an armed
interactive OAuth path cannot launch a real browser.
e2e.test.ts (and root scripts/smoke-cli.mjs) spawn the built binary for
shebang / process.exit paths — pretest builds test-servers + the CLI
bundle first.
Scripts (from clients/cli/)
npm test# pretest build + all tests
npm run test:cli # subset: cli.test.ts
npm run test:cli-tools # subset: tools.test.ts
npm run test:cli-headers # subset: headers.test.ts
npm run test:cli-metadata # subset: metadata.test.ts
npm run test:coverage # build + ≥90 per-file coverage gate
npm run validate # format:check && lint && typecheck && test
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