feat(lazurio): start hosted chats in the managed Lazurio Folder

[immakermatty]

A new Lazurio Environment currently opens T3's generic import wizard with no project to import, and new chats can start without the Folder context. Managed mode now adopts or creates the native Lazurio project during server startup, enforces the exact Folder root at the command boundary, and presents a dedicated welcome. Existing project/history data stays readable; new-chat actions converge on the managed Folder. Standalone upstream behavior stays unchanged without the optional hosting configuration.

The native settings service now reconciles a hosting model recommendation atomically, preserving a different user choice. Platform supplies the model/effort; this fork contains no product model recommendation. A read-only metadata CLI and a live-only reconciliation CLI avoid a second settings writer. Machines uses the versioned hosting capability contract. Every changed upstream client seam is listed in fork CI for future refreshes.

Verified: server/web typechecks; 84 focused native engine/settings/auth-route tests; 63 focused web tests after the historical-project routing adjustment; 22 release-contract tests; native CLI apply/reapply against an isolated running server. Browser rendered the managed welcome and opened a draft in Lazurio. Final UI cleanup, server/web rebuilds and the real Platform → T3 CLI consumer passed. Read-only metadata on an absent T3CODE_HOME creates no state. Browser screenshots are attached in the PR conversation. No customer runtime or database was changed.

Claude Opus 5.5 architecture/code/instruction audit found concrete migration and metadata issues; these were addressed, including moving reconciliation from the public settings patch into the native service. Final Opus follow-up found no blocking T3 issue. Coordinated dependencies: Lazurio/LazurioPlatform#358 owns the recommendation; Machines deployment wiring declares the mode. Production rollout and authenticated provider-account acceptance remain separate qualification gates. Prepared by Codex.

Additional acceptance: restarting the isolated native service retained exactly the same single Lazurio project ID, title and canonical Folder, and native model readback retained GPT-6.1 Sol / High. Independent Pablo review APPROVED exact head 1945d88; production authentication and rollout qualification remain separate.

[immakermatty]

Browser verification on an isolated test Environment: a single Lazurio project is ready without importing history; Start in Lazurio opens the draft at that root. Add-project and scratch-project entry controls are absent. The test runtime is intentionally signed out of provider accounts, so the draft screenshot is not evidence of authenticated model availability. Native settings and Platform CLI acceptance separately verified GPT-6.1 Sol / High and reapplication. No customer data or credentials were used.

[immakermatty]

Wording pass, at the Admin's request: he asked me to go through the texts of these PRs and rewrite them where they read badly. The behaviour stays the same. The welcome screen reads well. The messages people see when T3 refuses something use internal words ("retarget", "provides … at its Folder root", "T3 worktree"). Suggested replacements, as they are:

Where	Now	Suggested
managedFolder.ts, message	Start a new chat in the Lazurio project. This Environment starts agents in its Lazurio Folder; existing conversations remain available as history.	Start a new chat in the Lazurio project. Agents in this Environment work in its Lazurio Folder; your earlier chats stay here as history.
managedFolder.ts, project root	This Environment provides the Lazurio project at its Folder root.	In this Environment, the Lazurio project is the Lazurio Folder itself.
managedFolder.ts, rename	The managed project is named Lazurio.	This project keeps the name Lazurio.
managedFolder.ts, another folder	A managed Environment does not retarget projects. Use the Lazurio project.	In this Environment a project cannot point to another folder. Use the Lazurio project.
managedFolder.ts, removal	The Lazurio project is provided by this Environment and cannot be removed.	The Lazurio project belongs to this Environment and cannot be removed.
managedFolder.ts, worktree	Chats in this Environment start at the Lazurio Folder root, without a T3 worktree.	Chats in this Environment start in the Lazurio Folder, without a separate worktree.
ProviderCommandReactor.ts	This Environment starts agents in its Lazurio Folder. Start a new chat in the Lazurio project.	Agents in this Environment work in its Lazurio Folder. Start a new chat in the Lazurio project.
VcsProvisioningService.ts	The Lazurio Folder contains separate repositories and must not become a repository itself.	The Lazurio Folder holds separate repositories, so it cannot become a repository itself.

Please adjust the tests that pin these strings.

[agentrozjedemeai]

Independent review of exact head 1945d88: approved. Traced native startup/adoption, queued command refusal and provider canonical-cwd/VCS boundaries, historical-project web routing, user model preference reconciliation in the native settings writer, read-only CLI/status and authenticated apply, and fork seam allowlist. Local release-contract test: 22/22 passed; exact-head server/web, CLI archives and launcher CI are green. No production or authenticated inference qualification claimed. Platform -> T3 -> Machines release order remains separate; author owns publication.