Allow arbitrary MCP hostname

[blind-oracle]

Currently if MCP hostname does not overlap with any of base/custom domains - it doesn't work due to the base domain lookup failure.

This PR fixes it by reworking how MCP calls are handled: they're caught now early on and passed directly to the MCP router before any other middleware kicks in.

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to 8b09809.

Security Overview

• 🔎 Scanned files: 2 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/2f4ca4b6-3e66-473c-8350-2a581fad9f23?scanId=765d234b-334b-4ccf-82aa-f4b3043dcacd&codeScanTypes=PrScan&tab=issues

Detected Code Changes

Change Type	Relevant files
Enhancement	► src/mcp.rs     Implement IiType enum with Display and FromStr for custom MCP II instances ► src/mcp.rs     Add MCP state management (McpState) and middleware to route MCP requests ► src/mcp.rs     Update setup_mcp to return McpState and handle custom II instances ► src/mcp.rs     Add tests for IiType parsing (prod, beta, custom) and error cases
Enhancement	► src/routing/mod.rs     Remove hard dependency on extract_authority and extract_host in routing setup ► src/routing/mod.rs     Integrate MCP startup logic under feature flag and inject MCP middleware into router when enabled ► src/routing/mod.rs     Adjust API hostname handling to reflect changed API hostname source

[Copilot]

Pull request overview

Routes MCP requests before domain resolution, allowing MCP to use arbitrary hostnames.

Changes:

• Adds hostname-based MCP middleware.
• Updates arbitrary-hostname integration coverage.
• Adds custom Internet Identity configuration parsing.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/routing/mod.rs	Installs early MCP routing and updates tests.
src/mcp.rs	Adds MCP middleware, state, and custom II parsing.

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