[EhabY]

External app links now follow the same $SESSION_TOKEN rules as the dashboard (coder/coder#31208).

• The token is filled in only when the link opens a known Coder IDE handler, its url param is the sign-in URL or the deployment's dashboard_url from build info, and the placeholder is the token value.
• Dev container (sub-agent) apps have the placeholder removed before anything else, as coderd does since fix!: validate workspace app URLs on the server coder#31262.
• Links that need a token but don't match are shown disabled. The tooltip names both URLs when the link points to another deployment, and otherwise uses the dashboard's message.
• Links that don't open a known Coder IDE handler ask for confirmation before opening. "Don't ask again for scheme: links" saves the scheme in app-link-settings.json.
• SDK: read parent_id from the workspace agent and dashboard_url from build info.

Decision log

• Same rules as the dashboard: all clients agree on which links get a token.
• dashboard_url kept in memory, not saved: an admin can change the access URL, so it's fetched again on each launch and sign-in.
• Strip the placeholder for dev container apps: there's no token to protect, so old and new servers behave the same and the token can't reach those links.
• Disabled button instead of hiding the app: the tooltip says why it can't open and who can fix it.
• Flyout for the confirmation: the tray window is 300 px wide, narrower than ContentDialog's minimum width. LauncherOptions.TreatAsUntrusted is ignored in desktop apps.
• Confirm only links outside the known handlers: IDE links stay one click.
• Remember per scheme: like a browser's external protocol prompt. Stored in a new AppLinkSettings through the existing SettingsManager<T>, separate from the Coder Connect settings. A corrupt file shows the usual "Could not open app" error, like the Coder Connect settings.
• Check and replace on Uri.OriginalString: Uri.ToString() unescapes the link. The click checks again with the credentials whose token it uses.

Tests: CI build, fmt and test pass. The tray UI wasn't run by hand.

Generated with Coder Agents.