Patch release: background session control via new CLI subcommands, artifact publish notes, clearer subagent defaults, and prompt/behavior polish around focus mode, memory, and directory sync.
Changelog
[new] Background session management on the CLI: attach, logs, respawn, rm, and stop, plus an --all flag for bulk targeting.
[new] Artifact publishes can include an optional note — a short description of what changed in that version, shown beside the label in the version picker.
[new] MCP memory tool surface (memory) for reading and writing durable memory.
[changed] Subagent model overrides now respect a configured default subagent model when the agent definition does not set one (forks still always inherit the parent model).
[changed] Subagents default to running in the background so you can keep working or interject; use run_in_background: false only when the next step truly depends on the result. Spawning is reserved for explicit user requests, and prompts should carry concrete understanding (paths, line numbers, intended edits) rather than delegating synthesis.
[changed] Artifact publish replies treat the in-app card as the link handoff: describe the page in a sentence and avoid pasting the URL unless asked; /artifacts and the gallery remain the way back to owned or shared artifacts.
[changed] Focus mode guidance: only the final text of each turn is shown — skip mid-turn progress chatter and put everything the user needs in that final message.
[changed] Memory bookkeeping is machine-only: do not quote or paraphrase refresh blocks in replies; answer memory questions from file contents in your own words. Correction-driven memory writes belong in the same turn as the engagement, not deferred.
[changed] Stronger guidance when fetches fail or pages miss the mark: name the URL and HTTP status or error instead of filling gaps from memory.
[changed] Thread resolve on artifacts: only resolve activated threads you actually addressed; leave non-activated threads for the commenter or artifact UI.
[removed] Built-in Mcp tool entry retired from the core tool list (connector/MCP flows remain via the connector tools).
[removed] Legacy model IDs dropped from the catalog: claude-3-5-sonnet-20240620 and claude-sonnet-4.6.
Models & prompts
Optional model override on agents still accepts sonnet | opus | haiku | fable, with clearer precedence: agent frontmatter and the default subagent model, then parent inheritance.
Agent-tool copy stresses not spawning unless asked, not fabricating pending agent results, and proving understanding in delegated prompts.
New and tightened behaviour for artifacts (publish cards, version notes, cloud-session delete limits), multiplayer whiteboard creation when a live shared sketch is requested, focus mode, continuous/brief output styles, and SendUserMessage for user-visible mid-task content.
Directory-sync status copy when the cloud file service returns and local sync resumes.
Connector helpers remain available to list org MCP connectors and resolve full connector payloads from registry UUIDs.
API beta header code-execution-2025-08-25 removed from the client set.
Under the hood
Background dispatcher and bridge plumbing (rate-limit tier / subscription awareness, owner account and org binding, optional disable of MCP task backgrounding).
Model catalog comparison path and related session/host/SDK environment hooks for relaunch and first-party base URL assumptions.
Frame sync API route (/api/frame/sync) for bridge/subagent frame coordination.
Directory-sync worker signals for offline, back-online, settle, and watch behaviour.
SDK tool typings extended with contract preference / carried state, audience, and the artifact note field; tested SDK wrapper list no longer includes 0.3.211.
Leaner ship binaries across platforms (on the order of ~10MB smaller per target).
Upgrade notes
If you relied on claude-sonnet-4.6 or claude-3-5-sonnet-20240620 by exact ID, switch to a current Sonnet alias or ID.
Prefer the new session subcommands (logs / attach / stop / rm / respawn, with --all where applicable) for background worker control instead of ad-hoc process management.
When publishing artifact updates, set note if you want the version picker to explain what changed; omit it when there is nothing worth calling out.
Mouse-wheel zoom shortcuts are gone; rebind if you depended on ctrl+wheel or meta+wheel.
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