chore: release 0.2.40

CHANGELOG.md

@@ -3,6 +3,30 @@
 All notable changes to this project are documented here.
 The format is based on [Keep a Changelog](https://keepachangelog.com/).
 
+## [0.2.40] - 2026-08-08
+
+### Added
+- **Per-key spend accounting** on the API-keys page: requests, tokens in/out and cost per key
+  for a selectable window (24h / 7d / 30d) plus a cumulative all-time cost column — "which
+  department spends what" at a glance.
+- **Bounded stats on disk**: once `stats.jsonl` outgrows `stats.max_file_mb` (default 16, 0
+  disables), records older than the retention window fold into cumulative per-account totals in
+  a small sidecar file (tmp+rename on both) and leave the log. All-time accounting survives
+  compaction and restarts; nothing is ever counted twice.
+- **Per-complexity models inside a task rule**: each task is edited as rows of
+  "model + complexity" pairs — `[routing.tasks.code] low=["cheap"] high=["best"] any=[...]`.
+  The tier-specific pick leads its own tier, `any` (and legacy plain arrays) leads everywhere,
+  the global tier chain and `default` always remain as fallback, and high verdicts still
+  escalate over any-tier pins.
+
+### Changed
+- Benchmark hard probes are generated from wider interdisciplinary pools (6 families each) and
+  retry once with a fresh template — the router's novelty decay no longer flips them red.
+
+### Fixed
+- The `task-rule` badge is honest: it appears only when the rule actually chose the head of the
+  candidate chain, not whenever a rule merely exists for the task.
+
 ## [0.2.39] - 2026-08-07
 
 ### Added