[BUG] Cowork broken on macOS arm64: downloads.claude.ai serves 40MB tarball for claude-code 2.1.87, client expects 182MB (TAR_BAD_ARCHIVE)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

What's Wrong?

Cowork fails to start with "Failed to start Claude's workspace —
Download failed" on macOS arm64. Root cause: the CCD bundle
downloader retrieves the SDK tarball successfully, but the
downloaded size does not match the client's expected size,
causing the tar parser to see 0 bytes.

Evidence

From main.log:

[CCD] Initialized with version 2.1.87
[CCD] Downloading bundle from https://downloads.claude.ai/claude-code-releases/2.1.87/darwin-arm64/claude.app.tar.zst
[CCD] Download attempt 1/3 failed Error: TAR_BAD_ARCHIVE:
Truncated input (needed 191189504 more bytes, only 0 available)
[CCD] Download attempt 2/3 failed (same error)
[CCD] Download attempt 3/3 failed (same error)
[CCD] All download attempts failed

Client expects: 191,189,504 bytes (~182 MB)
Server serves: 40,745,941 bytes (~40.7 MB)

curl -vI output

HTTP/2 200
content-length: 40745941
x-goog-stored-content-length: 40745941
content-type: application/zstd
last-modified: Sun, 29 Mar 2026 02:09:35 GMT
etag: "e577d335112e38db0d5878974539199e"

The file has been sitting at 40MB on the CDN since March 29,
so this isn't a mid-upload race — it's a bad or incomplete
artifact upload.

Environment

• Claude Desktop: 1.569.0
• macOS: 26.4 (Darwin 25.4.0, build 25E246)
• Hardware: M2 Pro, 16GB
• Last known-working SDK version: 2.1.85 (worked through March 31)

Impact

Cowork is completely unusable. Every reinstall pulls the same
broken tarball. No local workaround possible — users are stuck
until either the CDN artifact is re-uploaded or Claude Desktop
ships a manifest pointing at a different version.

Workaround

None. Rolling back Claude Desktop to a pre-April build is the
only option for users who have a backup.

What Should Happen?

Cowork should start successfully. The CCD downloader should
either (a) fetch a tarball whose actual size matches the
expected manifest size, or (b) fail with a clearer error that
distinguishes "server returned wrong size" from "network
download failed" so users can diagnose the root cause without
digging through logs.

Specifically, the 2.1.87 darwin-arm64 tarball at
https://downloads.claude.ai/claude-code-releases/2.1.87/darwin-arm64/claude.app.tar.zst
should be re-uploaded to match the size (191,189,504 bytes)
that Claude Desktop 1.569.0 expects.

Error Messages/Logs

Steps to Reproduce

1. Install Claude Desktop 1.569.0 on macOS arm64 (M-series Mac,

macOS 14+).

1. Sign in with a paid plan (Pro/Max/Team/Enterprise).
2. Click the Cowork tab in the sidebar.
3. Observe "Failed to start Claude's workspace — Download failed.

Check your internet connection and try again."

1. Click "reinstall the workspace" — same error.
2. Check ~/Library/Logs/Claude/main.log and search for [CCD] —

observe TAR_BAD_ARCHIVE errors with "needed 191189504 more
bytes, only 0 available".

1. Run: curl -sI https://downloads.claude.ai/claude-code-releases/2.1.87/darwin-arm64/claude.app.tar.zst | grep -i content-length

Observe content-length: 40745941 (should be 191189504).

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.85

Claude Code Version

Claude Code Version: 2.1.87 (Cowork-bundled SDK, per vm-info.json) Claude Desktop Version: 1.569.0 Standalone Claude Code CLI (unrelated): 2.1.92

Platform

Claude Desktop / Cowork

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_