Patch release: optional artifact tab icons, stricter skill-description rules, Chrome connection/pairing hardening, and clearer agent guidance around subagents, focus mode, and sandboxed networking.
Changelog
[new] Artifacts accept an optional icon — a short generic word (for example chart, calendar, recipe, code, or map) used as the tab icon. Omit it on republish to keep the current icon.
[changed] Artifact favicon is documented as the artifact’s emoji (one or two emoji, no markup); still required on first publish and omitted on redeploy unless the user asks to change it.
[changed] Skill description values must not include angle brackets (still aim for under 200 characters, never more than 1024).
[changed] When a Chrome tool call never reaches the extension because the paired machine looks offline or asleep, the agent explains it as a connection problem and asks the user to wake the machine and open Chrome with the extension before retrying.
[changed] Deferred Chrome browser tools must be loaded via ToolSearch in one batched call (comma-separated select list) before use, instead of loading tools one round-trip at a time.
[changed] Tabs opened for the agent are cleaned up like tabs_create_mcp tabs: close with tabs_close_mcp when finished unless the user wants them kept.
[changed] Subagents stay background-by-default; run_in_background: false only when the next step truly depends on the result. Guidance covers remote CCR isolation, teammate limits, and not fabricating pending-agent results.
[changed] Sandboxed HTTPS can use opaque CONNECT tunnels for selected domain patterns (same syntax as allowedDomains) so mTLS and certificate-pinned clients complete their own TLS handshake; allow/deny lists still apply, but request filtering and credential injection do not on those tunnels.
[changed] On sandbox host denials in auto mode, retry with the host added to allowed_domains, or with dangerouslyDisableSandbox: true when appropriate.
[changed] Focus mode: only the final text of each response is shown — skip mid-turn progress chatter and put what the user needs in the last message.
[changed] Correction memories must be written in the same turn that engages the fix (before the reply or next tool step), not deferred until later.
[changed] Stronger push to leave Claude Code settings, hooks, skills, plugins, and the repo’s git hooks/config alone unless the user asks; end autonomous jobs with an actionable report (path, branch, PR, or answer).
[changed] Clearer handling when artifact/page comment threads are owned by the page itself (don’t retry relay-only replies) and when Cowork sessions can’t read files outside connected folders.
[removed] Scratchpad-vs-/tmp temp-directory instructions and the old “remind the user about GitHub repo access” prompt line.
Models & prompts
Optional fast-mode controls for Opus-class models via CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE and CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE (off unless set).
Agent prompts refine continuous/autonomous and brevity styles, permission-denied wording, conversation summary tasks (full session vs recent-only), and “plausible by default” review language.
Computer-use flow can upload a fresh screenshot into a file input or drag-and-drop target (ref or coordinate); screenshot IDs expire quickly and shouldn’t be reused after a failed upload.
Connector helpers remain available to list org MCP connectors and resolve registry directoryUuid payloads after a search — not for guessed names or UUIDs.
Under the hood
New local OAuth pairing route (/api/oauth/local_pairing) and CLAUDE_CHROME_PAIRED_DEVICE_ID for Chrome device pairing.
Timeouts and transport knobs: CLAUDE_CODE_CONNECT_TIMEOUT_MS, CLAUDE_CODE_WEBFETCH_DEADLINE_MS, web-fetch transport gating, and attribution announcement/status timeout settings.
Session/runtime context env vars for host session id, resume reason, tool-use id, gateway token, server-spawned runs, npm-wrapper installs, and short sync-reuse windows.
CLAUDE_CODE_QUESTION_OPTIONAL_DESCRIPTIONS for optional question description text.
CCR/disk safeguards (disk watchdog, low-disk signals, stream event hold/drop) and plugin menu auto-reload / close-and-reload behavior behind feature gates.
Org-policy denial and GitHub access precheck instrumentation; several older internal gates (including carved_slate) retired.
SDK wrapper compatibility tests drop 0.3.225 and keep 0.3.226 / 0.3.227.
Upgrade notes
If you author skills through the SDK or review cards, strip < / > from skill descriptions before saving.
Publishers of artifacts can pass icon for a simple tab glyph; keep using emoji via favicon when you want a custom emoji, and omit both on redeploy to preserve what users already see.
Chrome extension users who see “call never delivered” should confirm the paired computer is awake and Chrome is running with the extension, then retry.
Operators who need pinned-cert or mTLS upstreams through the sandbox proxy can rely on the opaque-tunnel domain list in addition to allowedDomains.
Optional env overrides above are unset by default; set them only if you intend to change timeouts, pairing, or fast-mode behavior.
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