[BUG] macOS Cowork: "Couldn't link this session to a computer" since Desktop 2.9939.2 — Secure Enclave sign fails with OSStatus -25308, td-v2 attestation mint unavailable

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet on macOS (related Linux reports: #79232, #83122, #77348)
• [x] This is a single bug report
• [x] I am using the latest version of Claude Desktop

What's Wrong?

Every cloud Cowork session on a Team workspace shows the banner "Couldn't link this session to a computer, so attached folders can't be used. Link it to this computer to use them." Attached folders are unusable. Accepting the folder consent dialog does not help.

This is on macOS (Apple Silicon), not Linux. The device is registered: ant-device-registry.json holds a pk1: value for the signed-in account, and the remote-tools bridge authenticates normally. The failure is at the per-session signing step. The Secure Enclave signature fails with OSStatus -25308 (errSecInteractionNotAllowed), and the td-v2 attestation mint fails right after the user approves the folder grant.

Session linking worked on the same machine and the same Team workspace on 2026-09-20 and 2026-09-22 (app 2.2553.1; logged verdict bound_no_rebind). The app auto-updated to 2.9939.2 on 2026-09-24. Since then, every session logs offered_late_link with bindingState: "unbound" and never binds. 2.7032.0 was installed on 2026-09-22 but no link attempts happened on that build, so I can't tell whether the regression came in 2.7032.0 or 2.9939.2.

The -25308 warning also appeared once on 2026-09-08 and once on 2026-09-16 on older builds, but binding still succeeded on those days. Today it appears on every app start and every link attempt.

The bundle has a coworkTrustedDevicesRequired / unsignedAllowed path. If the Team workspace requires trusted devices, a failed enclave signature means no unsigned fallback. That could explain why this shows up on Team and not on personal plans.

What Should Happen?

After the user approves the folder grant, the session binds to this Mac and the attached folders work. If the Secure Enclave refuses to sign, the app should retry in a context where macOS allows it, or show the real reason instead of the generic banner.

Error Messages/Logs

# ~/Library/Logs/Claude/main.log (2.9939.2)
2026-09-24 15:31:01 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn't be completed. (OSStatus error -25308.)] { code: 'GenericFailure' }
2026-09-24 15:31:02 [info] [remote-tools-device] device registered — refreshing row PK
2026-09-24 15:31:04 [info] [remote-tools-device] authenticated
2026-09-24 15:39:11 [info] grantRemoteSessionFolders: user allowed for cse_… (dwell 2515ms, remember=false)
2026-09-24 15:39:12 [warn] [remote-file-tools] td-v2 attestation mint unavailable: Error
2026-09-24 15:39:45 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn't be completed. (OSStatus error -25308.)] { code: 'GenericFailure' }
2026-09-24 15:41:05 [info] grantRemoteSessionFolders: user allowed for cse_… (dwell 3065ms, remember=true)
2026-09-24 15:41:05 [warn] [remote-file-tools] td-v2 attestation mint unavailable: Error

# ~/Library/Logs/Claude/claude.ai-web.log
# Working, 2.2553.1:
2026-09-22 15:57:39 [warn] [LOCAL_SESSION] remote_cowork.late_link_offer_verdict {"verdict":"bound_no_rebind","gateOn":true,"signSessionBind":true,"ownRow":"resolved","keyless":false,"refused":false,"bindingState":"bound"}
# Broken, 2.9939.2 (every session since the update):
2026-09-24 15:41:01 [warn] [LOCAL_SESSION] remote_cowork.late_link_offer_verdict {"verdict":"offered_late_link","gateOn":true,"signSessionBind":true,"ownRow":"resolved","keyless":false,"refused":false,"bindingState":"unbound"}

Steps to Reproduce

1. On macOS 27.0 (Apple M5 Pro), sign in to Claude Desktop 2.9939.2 with a Team workspace account.
2. Start a cloud Cowork task with a local folder attached.
3. Approve the folder consent dialog.
4. The session shows "Couldn't link this session to a computer…" and the folder can't be used. Fully quitting and relaunching the app doesn't help.

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Claude Desktop 2.2553.1 (last confirmed bind 2026-09-22)

Claude Code Version

Claude Desktop 2.9939.2 (Cowork)

Platform

Anthropic API

Operating System

macOS 27.0 (26A428), Apple Silicon (Mac17,9, M5 Pro)

Additional Information

• The Mac is MDM-managed (Intune). The login keychain is unlocked with no timeout.
• The account previously used a personal plan on this machine, where binding also worked. I moved to a Team workspace around 2026-09-20.
• Workaround: running the task as a local (on-this-computer) session avoids the link step.

The device this session is bound to is not connected to the bridge.

2026-08-26 00:04:44 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn’t be completed. (OSStatus error -25308.)]
2026-08-29 13:26:14 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn’t be completed. (OSStatus error -25308.)]
2026-08-30 18:54:13 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn’t be completed. (OSStatus error -25308.)]
2026-09-22 17:54:54 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn’t be completed. (OSStatus error -25308.)]
2026-09-22 20:57:28 [warn] [device-registry] enclave sign failed: [Error: hardwareKey: SecKeyCreateSignature failed: The operation couldn’t be completed. (OSStatus error -25308.)]