Enhancement: support richer host-passed context for buddy_observe so reactions can reflect actual code changes

[terpjwu1]

Problem

Buddy does not inspect diffs on its own during buddy_observe; it only knows what the host passes in. Right now, the default experience is mostly summary-driven, which limits how accurate Buddy can be when making code-related comments.

Request

Expand the host-to-Buddy contract for buddy_observe so hosts can optionally pass richer structured context, for example:

• changed files
• high-level diff summary
• explicit test status
• deployment status
• structured claims derived from the actual code changes

Why this matters

This would let Buddy make more grounded reactions without requiring Buddy itself to shell out to git or become a full code analysis engine. It keeps Buddy lightweight while enabling hosts to provide better evidence.

Suggested directions

Possible additive fields for buddy_observe:

• changed_files
• tests or verification
• artifacts
• diff_claims or another structured evidence block

Benefits

• better technical relevance in Buddy reactions
• less reliance on generic fallback text
• cleaner path for MCP hosts to integrate real work context
• preserves current behavior as a backward-compatible fallback when only summary is provided

Non-goal

This request is not asking Buddy to become fully diff-aware by itself. The focus is enabling better host-provided context first.