[BUG] Linux: "Couldn't link this session to a computer" still on 1.24012.9 -- td-v2 device registration never succeeds (#79232 closed as completed, fix not on apt stable)

Preflight Checklist

• [x] I have searched existing issues: #79232 covers the same root cause but is closed as completed
• [x] This is a single bug report
• [x] I am using the latest version (claude-desktop deb 1.24012.9, apt stable channel)

What's Wrong?

On the Claude Desktop Linux beta, every Cowork session still shows "Couldn't link this session to a computer, so attached folders can't be used" and is provisioned with unbound folders.

#79232 traced the root cause (claude-native has no enclave-key implementation on Linux, so td-v2 device registration can never succeed) and was closed as completed on 2026-07-19. However 1.24012.9 (released after that date and currently the newest build on the apt stable channel) still reproduces it:

• main.log: [warn] [remote-file-tools] td-v2 attestation mint unavailable: DeviceRegistry: device not registered (no row-PK for this account)
• ~/.config/Claude/ant-device-registry.json only ever holds "none:<timestamp>", refreshed on every lookup; it never reaches a pk1: value. Clearing the cached entry does not help: the none state is rewritten on the next lookup, matching the update note in #79232.
• No [trusted-device] enrolment line has ever appeared in the logs on this install.
• Everything else is healthy: the sessions-bridge registers its environment, the wss connection to bridge.claudeusercontent.com authenticates, and a pre-existing remote session reconnects fine.
• The Cowork local VM is also unavailable on Linux ([startVM] VM not supported (linux/x64), skipping, #77348), so there is currently no folder-capable path at all on this platform.

Steps to Reproduce

1. Install claude-desktop 1.24012.9 from the official apt repo on Ubuntu (x86_64, GNOME/X11) and sign in.
2. Start a Cowork session and attach a local folder through the desktop app.
3. The session shows the "Couldn't link this session to a computer" banner and the attached folders are unusable. App restarts and clearing ant-device-registry.json make no difference.

Expected Behavior

Device registration succeeds (registry value flips to pk1:<hex>) and Cowork sessions can bind attached folders. If the Linux enclave-key implementation shipped in a different version or channel, that build should reach apt stable. If Linux support is still pending, please reopen #79232 or document the limitation in the Linux beta docs so users don't chase local causes.

Environment

• claude-desktop 1.24012.9 (deb, downloads.claude.ai apt stable)
• Ubuntu (GNOME, X11), x86_64