0.15.2 — deferred-tier re-evaluation

Usage-driven re-eval of the deferred tool tier (211 transcripts, 13K tool calls).

Promoted to always-declared (4):

• munin_search / munin_get — the Memory Protocol's before-acting rule is a search; the old deferred tier forced a tool_search round-trip in front of it.
• github — top deferred-tier user (61 calls/17 sessions, all pre-dating the deferral); since deferral, release verification fell back to raw bash gh, forfeiting the wrapper's deadline, output cap, and read-only guardrails.
• ux_audit — every ux_* skill routes into it pre-code and the ux module is always loaded; the tier was a pure-latency detour.

52 tools stay discover-only via tool_search (serena, a2a, web cold tools, sg, fff extras, munin store/list/…, jfind, cron, shell, notify, rule_get). Declared tool block ~438 → ~507 tokens — still ~47% below the pre-deferral ~955.

Docs swept (AGENTS.md, README), stale defaultTools docstring fixed, +registry tier guard test.