Claude Code Set Fast Mode to Opus 4.7 — Plus 8 New Agent Flags

#claudecode #opus47 #aicoding #backgroundagents

Claude Code unlocked background again — Fast mode is now 4.7

Bottom line first. Claude Code's Fast mode default auto-switched to Opus 4.7. The same changelog batch also shipped 8 new claude agents CLI flags, an option to turn off worktree isolation, and enforced plugin dependencies — all at once.

Here's a fresh batch from the Claude Code changelog. The Fast mode default jumped from Opus 4.6 to Opus 4.7, and three options that strengthen autonomous background execution came along with it. This is the follow-up round right after the May 14 release of the four commands /goal·/loop·/batch·/background.

If the previous round was about "slash commands that don't stop every turn," this round is about dispatching background sessions more precisely at the CLI level. It's all one coherent batch, so I'm covering it in a single post.

01 · Fast mode switch: it auto-switched from 4.6 to 4.7

	Before (~May 16)	Now (new default)
Model	Opus 4.6 — Fast mode default	Opus 4.7 — Fast mode default
Hard SWE	59%	higher
Response speed	standard	kept
Token price	same	same

If you were running Fast mode, Opus 4.7 gets picked up automatically from your next session after the update. Only if you'd pinned the environment variable CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1 do you stay locked to 4.6. Price is unchanged and hard-SWE performance is up versus 4.6, so it reads as close to a free upgrade.

02 · Background agents: `claude agents` picked up 8 flags

The claude agents command — the one you use to dispatch background sessions from the CLI — gained 8 options in one shot. You can now set permissions, model, effort level, and MCP config per session.

--add-dir — extra working directory. For multi-repo work, surfaces directories beyond the main cwd.
--settings / --mcp-config — isolated settings & MCP. Connect a different MCP server for just this session without touching your base settings.json.
--plugin-dir — plugin isolation. Disable global plugins and load a separate set for this session only.
--permission-mode — force a permission mode. Force acceptEdits / plan / bypassPermissions etc. per session.
--model / --effort — set model & effort directly. Tune sonnet / opus and effort level separately for each background session.
--dangerously-skip-permissions — YOLO mode. Fully trusted container environments only — never on a normal workstation.

The takeaway is simple. It's now easy to run several background sessions with different profiles on one workstation at the same time. Session A on plan mode + sonnet, session B on acceptEdits + opus 4.7, session C on dangerously-skip inside a container — decided in a single CLI line.

03 · Worktree: there's now an option to turn off bgIsolation

New setting: worktree.bgIsolation: "none"

Meaning: instead of creating a separate worktree via EnterWorktree, the background session edits your current working copy directly. The risk of concurrent-edit conflicts now falls on you.

Previously, background sessions went through automatic git worktree isolation for safety. Safe, but it came with the friction of "the results never show up in my main working directory." This option lets you turn that isolation off. It's handy for a solo operator who wants to check results fast in a single working directory. In a multi-session concurrent-edit setup, keep it on to stay safe.

04 · Plugin: `/plugin` now shows the cost up front

In the /plugin marketplace browse panel, a plugin's per-turn token estimate moved from found after install → shown before install. A plugin's per-turn / per-invocation token estimate is now surfaced at the marketplace stage. You can spot which plugin eats tokens before installing it.

The other change in the batch is a stronger claude plugin disable. If another active plugin depends on this one, it refuses to disable it. That's a signal the plugin dependency graph is starting to be exposed to users — reads like the plugin ecosystem has entered a real operational phase.

Team impact

From a team's perspective, the biggest change is the Fast mode = Opus 4.7 auto-switch. No action needed — it applies from your next session.

Applies now: Fast mode users get 4.7 automatically from the next session. Check the hard-SWE response quality difference.
Optional: The 8 claude agents flags / bgIsolation are worth learning only for teams running background sessions seriously.

"If slash commands were the doorway to autonomous execution, these 8 CLI flags are the option that turns one workstation into a multi-session control tower."

— Eddie · 2026/05/17

Three things to watch over the next week: hands-on impressions of Fast mode 4.7 · real-world use of the agents flags · how trustworthy the plugin cost display is. All three are operational-phase signals.