Add SOVRINT governed-session profiles across TypeScript, Python, and Go

[katrinapietro05-design]

Summary

Adds an opt-in SOVRINT™ governed-session extension to the existing Copilot SDK without changing the upstream JSON-RPC protocol or existing client/session methods.

Runtime additions

TypeScript

• SovrintSecurityProfile and built-in strict, read-only, and research profiles;
• most-restrictive permission-handler composition;
• tool-surface, MCP, skill, and custom-agent filtering;
• system-message replacement protection;
• guarded custom-tool wrapper;
• bounded audit-event model;
• package-root exports and unit tests.

Python

• equivalent profile dataclass and built-in profiles;
• governed session configuration;
• composed permission handler;
• custom-tool wrapper;
• bounded audit events;
• package-root exports and tests.

Go

• equivalent profile, permission, session, tool, and audit helpers;
• built-in profiles;
• tests against native SDK types.

.NET

• governed-session cookbook pattern using verified native SessionConfig, tool, and system-message interfaces.

Common architecture

• SOVRINT extension architecture;
• security profile;
• governance, integrity, and evidence boundaries;
• API map and deployment checklist;
• strict and read-only JSON profiles;
• research profile template;
• profile and audit-event schemas;
• permission matrix and audit taxonomy;
• redacted simulation audit event;
• extension manifest, attribution, changelog, and root index;
• cross-language GitHub Actions validation.

Security semantics

• unknown permission kinds deny;
• explicit profile denial cannot be overridden by an application evaluator;
• existing permission-handler denial is preserved;
• built-in profiles forbid system-message replacement;
• strict mode exposes an explicit empty first-party tool surface;
• fail-closed profiles deny when audit recording fails;
• custom-tool events exclude arguments and results;
• local profile approval is not represented as global governance authority;
• audit events are not represented as EvidenceGrid acceptance.

Compatibility

• existing SDK behavior is unchanged unless an application imports and applies the SOVRINT helpers;
• package names remain unchanged;
• Copilot CLI server protocol remains unchanged;
• upstream attribution and repository licensing remain unchanged.

SOVRINT extension author: Katrina Pietroniro