Release v0.27.21

What's Changed

• feat(agent): default subagents to background execution by @overlord-letta in #3161
• feat(tools): support exec_command descriptions by @just-cameron in #3130
• fix(cli): validate auto-approved TUI tool args by @carenthomas in #3176
• refactor(goal): remove built-in goal mode by @kl2806 in #2792
• fix(memfs): centralize startup memfs enablement by @carenthomas in #3160
• fix(model-selector): show discovered local models in recommended tab by @ezra-letta in #3175
• fix(cli): show local favorites in pinned agents by @carenthomas in #3184
• fix(providers): promote chatgpt_oauth as canonical providerType for openai-codex by @carenthomas in #3182
• fix(cli): back pins with favorite tags by @carenthomas in #3185
• feat(ci): add Codex agent watcher by @carenthomas in #3190
• refactor(mods): use ModContext for statusline panels by @carenthomas in #3189
• fix(cli): validate approval args from scoped tool schemas by @carenthomas in #3191
• feat(mods): expose conversation summary in context by @carenthomas in #3193
• fix(mods): enable mod permissions in listener/desktop runtime by @carenthomas in #3199
• fix(reflection): gate queued step-count launches by @carenthomas in #3196
• feat(mods): add agentId to ModBackgroundAgentContext by @carenthomas in #3200
• fix(test): update listener mod adapter test for permissions capability by @carenthomas in #3201
• feat(listener): send stable listenerInstanceId when registering environments by @cpacker in #3197
• refactor(memfs): make memfs mandatory — remove all non-memfs opt-outs by @cpacker in #3202
• feat(listener): include image assets in list_memory responses by @cpacker in #3204
• feat: export agent creation presets as @letta-ai/letta-code/agent-presets by @cpacker in #3206
• fix(app-server): Emit app-server approval control requests by @jnjpng in #3205
• chore: bump version to 0.27.21 by @github-actions[bot] in #3208

Full Changelog: v0.27.20...v0.27.21