No UI feedback for Lemonade model download, busy state, or connection loss

[itomek-amd]

Problem

GAIA has no mechanism to communicate Lemonade's internal state to the user. This creates three distinct failure experiences that all look the same — a generic error — when the underlying causes and correct user actions are completely different.

Observed Behaviour

1. Model still downloading — Lemonade shows ~90% progress internally, but GAIA displays "No model loaded" in the top-right corner. Sending a query results in GAIA spinning on "Thinking…", flashing "Cannot connect to GAIA agent" briefly, then eventually returning: "I wasn't able to generate a response, please make sure Lemonade server is running and try again." The message is inaccurate — Lemonade IS running, it's just not ready yet.

2. Lemonade busy / warming up — When Lemonade is busy loading or processing, GAIA gives no indication of this. The user sees a generic connection error with no context.

3. Genuine connection loss — Currently indistinguishable from cases 1 and 2 above.

Expected Behaviour

GAIA should surface Lemonade's state with distinct, accurate messaging for each case:

Lemonade State	Desired GAIA UI Response
Model downloading	Status indicator: "Downloading model… (X%)" — disable input or show soft warning
Model loading into memory	Status indicator: "Loading model, almost ready…"
Lemonade busy / slow first response	"Model is warming up, this may take a moment…" instead of an error
Genuine connection loss	Clear error: "Cannot reach Lemonade. Is it running?" with retry option
Timeout during download	"Model is still downloading. Please wait until Lemonade is ready before sending a query."

Proposed Approach

1. Poll Lemonade's status endpoint (if available) on startup and surface download/load progress in the GAIA status bar
2. Distinguish timeout errors by checking Lemonade availability before surfacing a user-facing error — if Lemonade responds but the model isn't ready, show the appropriate waiting state rather than a failure
3. Disable or soft-lock the chat input while the model is not yet ready, with a clear explanation why

Impact

• First-run experience is broken — new users will think GAIA is broken when the model is simply still downloading
• No path to self-serve recovery — the current error message tells users to check if Lemonade is running, which is correct advice for connection loss but wrong advice for a download-in-progress
• Affects all platforms on first install

[kovtcharov]

Status: Partially Fixed

What works: ConnectionBanner tracks isDownloadingModel/isLoadingModel states. Shows banner with download/load UI when model unavailable. useModelActions() provides downloadModel() function.

What's still missing: No streaming progress during download — just binary downloading/not-downloading. No percentage, bytes downloaded, or ETA. User sees a spinner but no indication of how long it will take.

Remaining work:

• Add download progress percentage (requires Lemonade Server to report progress)
• Show bytes downloaded / total size
• ETA estimate
• Connection loss detection and reconnection feedback