stage-batch39: stamp v0.51.157 / Release EC

5-PR mixed-risk cleanup:
- #3090 gateway-chat forwards prefill+session-context into delegated Gateway turns
- #3091 sidebar keeps newer compressed continuation visible; lineage-aware state-db dedupe; session-arc marker exclusion
- #3092 browser-transcript memory guidance prompt addition
- #3093 reasoning-effort max parity with hermes_constants
- #3094 webui_prefill_context_max_chars budget (default 12000) for prefill payloads

Author: nesquena-hermes

CHANGELOG.md

@@ -3,6 +3,8 @@
 
 ## [Unreleased]
 
+## [v0.51.157] — 2026-05-28 — Release EC (stage-batch39 — 5-PR mixed-risk cleanup: gateway prefill forward + prefill budget + compressed-continuation sidebar + browser-transcript memory guidance + reasoning max parity)
+
 ### Added
 
 - The reasoning-effort selector now offers a `max` level, matching the agent's `hermes_constants.VALID_REASONING_EFFORTS`. This restores parity with the underlying set (the WebUI mirror previously stopped at `xhigh`) so providers such as Anthropic that support the `max` thinking level are selectable from the composer dropdown and the `/reasoning` command.