Your default model changed, and spend gets a cost code.

01 · What changed

What Anthropic shipped this week.

This roundup covers one change most users will notice and several that matter to admins, compliance and engineers. The default model moved to Opus 5.5, which costs more per token than Sonnet 5.5, so the guidance you gave people on which model to use may now be out of date. Enterprise admins got cost-code tags and Security posture data in the Compliance API, both in beta. Claude Code shipped three releases with new admin controls, and Anthropic launched the roadshow for its proposed initial public offering.

1. 1

   Opus 5.5 is the default

   Opus 5.5 is now the default model on Pro, Max, Ultra and Team plans. Anthropic lists it at $4 / $20 per million tokens (input / output), against $2 / $10 for Sonnet 5.5 and $0.10 / $0.50 for Haiku 5.5.

2. 2

   Cost-code project tags

   Eligible Enterprise organizations can tag projects with codes they already use, like a charge code or client-matter number, and see most spend in those projects by tag. The feature is in beta.

3. 3

   Security posture API

   The Compliance API now returns an organization's current Security posture results, in beta for Claude Enterprise. The Activity Feed records changes to attestations on the Security posture page.

4. 4

   Thinking blocks across models

   Claude Fable 5.2 and Claude Mythos 5.2 read other models' thinking blocks on the Claude API and Claude Models on Google Cloud (Google managed). No other model reads theirs: moving off either one drops those blocks, and the request still succeeds.

5. 5

   Claude Code admin controls

   Version 2.1.319 adds a setting that denies a tool call instead of waiting on a permission prompt, a way to stop feature-flag fetching without turning off telemetry, and spend for today, this week and this month in /usage for developers behind a Claude apps gateway with no spend limit.

6. 6

   Claude Code Mode and more

   Version 2.1.323 adds Code Mode, an experimental opt-in in which Claude writes JavaScript to call its tools, and an organization can turn it off. Version 2.1.322 adds fast mode on Vertex in the global, us and eu regions.

7. 7

   Claude for Manufacturing

   A plugin with 17 skills that drafts quotes, quality reports and supplier requests from a plant's own records, for a person to review and approve. It connects to Autodesk Fusion, Infor, Microsoft 365 and Oracle NetSuite.

8. 8

   Anthropic IPO roadshow

   Anthropic has launched the roadshow for a proposed offering of 825,000,000 Class A shares, expected between $70.00 and $78.00 per share. It has applied to list on the Nasdaq Global Select Market under the symbol ANT.

02 · What it means

What it means for your seat.

For most firms the change people will feel is the new default model: the same chat window now runs Opus 5.5 unless someone picks another. The rest of the roundup is for the people who run Claude: finance can start mapping spend to the codes it already uses, compliance gets attestation data through an API, and engineers have new rules about thinking blocks and new Claude Code controls.

03 · This week

0 of 3 done

1. 01 · Update your model guidance: Tell people Opus 5.5 is now the default on Pro, Max, Ultra and Team plans. Say when Sonnet 5.5 or Haiku 5.5 is the better pick, for example a quick lookup or a weekly status report from a clear brief.
2. 02 · Map project tags to your existing codes: If you are on Enterprise, check whether your organization is eligible for project tags. Pick the charge or client-matter codes you already use and tag a few projects while the feature is in beta.
3. 03 · Set your Claude Code policy: Decide whether Code Mode stays off for your organization and whether permissions.denyInsteadOfPrompting suits your unattended sessions. Write the decision into your managed settings.

The short answers.