Support native TanStack server entries and Next.js proxy

[patchstackdave]

Stack

Part 3; depends on #348.

Changes

• Guard the documented native TanStack Start Fetch entry without requiring a Supabase layout. Preserve host arguments, receiver, request body, and application errors.
• Support Next.js 16 proxy files with conservative composition; refuse conflicting entries or unsupported routing.
• Screen native TanStack requests by default and filter the response inside middleware result objects.
• Document separately hosted backend limitations and add synthetic framework fixtures plus a real public TanStack package consumer check.

Validation

• Full suite: 4,183 passed, 7 skipped (244 files).
• Build and typecheck: 10 guard templates.
• Real TanStack consumer: native and paired entry scaffolding, verification, and TypeScript checks passed.
• Capability and install-prompt checks passed.
• No proprietary builder templates or live-hosting certification. The agent install guide post-publication hostile field gate remains required before broad rollout.

Public-boundary review completed; fixtures are synthetic.

[coderbuds]

Extensive CI, docs, and adapter updates for Next.js proxy and TanStack Start integration.

🎯 Quality: 63% Average · 📦 Size: Large — consider splitting if possible

🛡️ Standards: Not checked — 580 lines changed, over your team's 400-line limit, and nothing checked before it was opened. Coding agents can call the assess-change-fit tool first, while a change this size is still cheap to split.

🤖 Authorship: Probably agent-written — OpenAI Codex, going by its branch name. Whether a person read it is unknown; coding agents can call the report-ai-usage tool to say.

📈 This month: Your 206th PR — above team average · Averaging Good

_{See how your team is trending →}

[patchstackdave]

Review fixes pushed in 1f1dba1.

• Preserve alternate TanStack server entries rather than creating a higher-priority/default file that could bypass existing application logic.
• Require statically established default routing before automatic composition. Imported options, configuration factories, spreads, computed properties, and competing entries report manual integration.
• Verify the generated Fetch helper before importing it.
• Added synthetic edge cases and packaged-CLI checks against the real public TanStack framework.

The combined stack passes 4,258 tests (7 skipped), typechecking of 10 templates, build, and capability checks. This PR is rebased onto the updated helper-safety and runtime PRs.

[patchstackdave]

/review