The internal per-session context object gained many new fields covering effort, hooks, tools, and skills
The internal context object that gets passed around during a session's agent loop (the internal cycle handling tool use and hooks) has grown a large number of new fields, including effort, effortLayerOverride, thinkingConfig, resolverState, teammateContext, agentLifecycle, toolAliases, proactivitySetting, sessionHooksRegistry, refreshTools, refreshMcpClients, stickyBetas, agentDefinitions, appendSystemPrompt, webBrowser/setWebBrowserSlice, shellPermission, unlayeredPermissions, sessionEnvVars, markPrResolvedThisSession, userTypedShellDispatch, emitToolProgress, mcpState, turnStartIndex, spawnedBySkill, spawnedByForkedSkill, mcpCommands, and loopOptions.
This is internal plumbing that expands what information tools, hooks, and other session logic can access at runtime; it doesn't by itself change visible behavior but underpins other features that need this state.