Evaluate native MCP routing instruction profiles

[hmishra2250]

Summary

• preserve stock MCP instructions as the default
• add authenticated and keyless capability-honest experimental profiles
• deliver profiles only through native MCP initialize.instructions

Experiment result — do not promote to default

P3 ran 384 immutable Convex-backed traces across Claude Sonnet 5 and Codex Terra using naturally discovered stdio MCP configuration with no Firecrawl CLI, skills, context card, forced --mcp-config, or injected instruction file.

• authenticated router profile: 0% → 0%, 0pp on both harnesses, adjusted p = 1.0
• keyless router profile: 0% → 0%, 0pp on both harnesses, adjusted p = 1.0
• safety: 1/96 matched regression; simultaneous upper bound 6.14%, above the 5% gate
• a separate eight-cell mechanism diagnostic found no behaviorally accessible profile-specific startup text in either harness

Recommendation: reject initialize.instructions as a router-card delivery surface for natural Claude Code and Codex CLI sessions. Keep stock instructions capability-honest, but do not merge these profiles as a routing feature unless maintainers explicitly want research-only profile support.

Decision artifact: Convex kg23nxb3s0gvqg8pcdqc2szqwh8arz95. Diagnostic artifact: Convex kg27gt5j74h2d59jzzcp7s5zx98arfqp. Raw traces remain in Convex.

Verification

• npm test (11 passed)
• npm run lint
• GitHub build check passes