v0.15.13

[0.15.13] - 2026-09-16

Added

• a3s code harness accepts a host session profile (agent dir, tool surface,
  policies) and proves it on a probe session (#138 / #136).

Changed

• Pin a3s-code-core to published =8.5.9 at git rev
  b5289bb4e6d405e2716654cba048d538c6630266 (tag v8.5.9).
• Align Use 0.3.x installation-scoped extension receipt paths and Plugin
  Manager MCP observe/watch/cancel inventory in remote-registry tests.

Fixed

• Host-waive code_exec writes for Core completion-gate fixtures; first-use
  and registry fixtures track Use schema 5 / host protocol 0.3.x.