[saurabhjain1592]

Scope

• Direct axonflow.community.register_try() callers at the canonical Hosted production and staging origins to verified Portal signup before an HTTP request. The guard uses HTTPX's own host normalization, including trailing DNS dots and IDNA dot equivalents.
• Preserve custom self-hosted Community registration. Update the README, sandbox guidance, and changelog for verified account and plan setup with linked API credentials.
• Add unit coverage and a guarded real-staging Portal and Agent proof.

Exact-head local evidence

Head: 1d5a5799e53bf53f4fb93c214256305d8e0b099e, rebased on SDK main 3d7b656eb19902ee01271ef8bb4f12e10c19a892 (contains #271 and #272).

• Python 3.11 full suite: 1,645 passed, 30 skipped, 86.17% coverage.
• Ruff check and format, mypy, falsey-clobber baseline, AuthZEN generated types, version alignment, no-mocks runtime E2E lint, and git diff --check passed. Wire-shape marker run: 12 passed, 8 designed skips without external OpenAPI specs.
• Built a wheel from this head and installed it in a fresh external venv. Consumer smoke passed eight Hosted hostname guard variants without HTTP, custom Community registration, and linked Hosted client construction.
• Independent code review found and verified a fix for the HTTPX IDNA hostname bypass; final review has no remaining actionable findings. Final-head Codex Security diff scan 770acc08-8527-43ad-93b8-a94ff7042b82 reviewed all changed files and found no reportable issues.
• The guarded runtime-e2e/hosted_first_run/test.py requires exact staging origins and a linked staging client. Its live Portal and Agent path was not rerun after the earlier synthetic credential was revoked. An earlier merged-main installed-wheel proof exercised the linked staging Agent; this PR changes the registration guard and guidance, not the Agent call path.

Remote Actions fail before job steps because the GitHub account is locked for billing. DCO passes. The local exact-head results above are the CI-down gate. No PyPI publication or deployment is part of this PR.