v0.17.1

v0.17.1

Two additions that were written the same day as v0.17.0 but were left unmerged on feature branches and missed that release. Both land here instead.

• ToolRelevanceIndex + the tool_search meta-tool (packages/agent/tools, relevance.py). Embeds and ranks a tool catalog against the current turn's query, returning the top-k most relevant tools with an LRU cache keyed on the catalog identity; a tool_search BaseTool wrapper lets a model reach anything filtered out of the initial top-k on demand. Falls back to the full, unfiltered catalog on any embedding failure or when ranking exceeds a configurable latency ceiling -- a degraded turn is never worse than today's full-catalog behavior. This is the platform primitive metallm's own dynamic tool-relevance selection consumes.
• acting_as_principal_id on AuditEvent (packages/agent/audit, envelope.py). 14-eng-ai-bot-identity's impersonation flow (identity.impersonation.start/stop) needs to record both the impersonation TARGET (actor_user_id, whose session it is) and the ADMIN actually driving it. Previously that producer carried the admin identity in details["acting_as_principal_id"] -- works on the wire, but isn't a typed, Hub-queryable column. Additive only: optional, defaults to None, every existing producer unaffected.

Full Changelog: v0.17.0...v0.17.1