## Why
The TUI must inspect the default execution environment before loading its final
configuration. Initializing the environment manager at that point can give
startup services the bootstrap HTTP policy instead of the effective policy after
managed requirements are applied.
## What changed
- Split environment discovery from manager construction so callers can inspect
the default environment without starting remote connections.
- Build the environment manager after final configuration loading and pass its
resolved `HttpClientFactory` through all construction paths.
- Add shared test support for managers that use the legacy default HTTP policy.
## Testing
- Cover connection-free environment discovery and explicit HTTP policy
propagation.
- Verify TUI startup services use the final managed `respect_system_proxy` value.
GitOrigin-RevId: 928fa31e6b4bcfbe1a121cade2f351427fdfa0f4
## What changed
- Let deferred environments provide selected capability roots with their ready signal.
- Validate that those roots have unique, non-empty IDs, belong to the registering environment, and stay within the root limit.
- Include roots from ready turn environments when resolving MCP contributions, and refresh the MCP runtime when the selected root set changes.
- Expose the exact ready root set to MCP contributors so executor plugins become available with their environment.
## Testing
- Cover ready-root propagation, validation failures, replacement isolation, reconnection, and MCP plugin availability refresh.
GitOrigin-RevId: ec3498aab1164824025094e96a9b1063b7b731ad
## What changed
- Track connected and disconnected states across initial remote exec-server connections and reconnection attempts.
- Emit experimental `thread/environment/connected` and `thread/environment/disconnected` app-server notifications for each thread selecting the environment. Each payload identifies the thread and environment; current state is not replayed when a thread starts.
- Stop forwarding connection events when an environment selection is removed or replaced.
## Testing
- Cover connection, disconnection, reconnection, shared-environment notifications, and replacement of a selected environment.
GitOrigin-RevId: 5dd767372363c4a2a8319fc16164be117d5bd20c
## What changed
- Replace pending WebSocket URL registration with deferred Noise environment
registration that gates connection attempts on an explicit readiness signal.
- Reuse the Noise rendezvous transport after readiness so reconnects request a
fresh connection bundle.
- Preserve terminal errors for failed or dropped registrations and keep late
completion isolated from replacement environments.
## Testing
- Add coverage for readiness gating, registration failure and replacement,
eager Noise connections, and reconnection through a fresh rendezvous bundle.
GitOrigin-RevId: 83e23fa03a02e3b2bdf1a83fe26d7ac461f55cf3
