v0.200.0

What's Changed

• fix(tools): moving a tool into subagent_only isn't announced as "No longer available" by @mabry1985 in #4104
• docs(proto): epic branches — review slice by slice, land the epic by attestation by @mabry1985 in #4110
• fix(completion-guard): retry a reasoning-only turn once with thinking off, its loop not replayed by @mabry1985 in #4115

Full Changelog: v0.199.0...v0.200.0