**Breaking change for changelog:**
> `codersdk.Chat.last_error` now returns a structured `ChatError` object
(`{message, kind, provider, retryable, status_code, detail}`) instead of
a plain string. The chats API is experimental
(`/api/experimental/chats`), so this ships without a deprecation cycle;
consumers reading `chat.last_error` as a string must update to read
`chat.last_error.message`. SDK/generated TypeScript terminal error
payloads now use the single `ChatError` type; the live stream error
payload type is renamed from `ChatStreamError` to `ChatError`.
Persisted chat errors now carry the same provider-specific detail (kind,
provider, retryable, HTTP status, optional detail) as the live stream,
so refreshing a failed chat rehydrates with the full structured error
instead of a one-line headline.
Existing rows are migrated in place: legacy text errors are wrapped into
`{message, kind: "generic"}` so already-errored chats still render, and
rows with `last_error IS NULL` stay NULL. Internally, persisted fallback
decoding now reuses the existing `chaterror.KindGeneric` constant, with
no JSON value change.
Closes CODAGT-239
- Replaces the hard-coded 500ms reconnect timer for dialing chat relays with exponential backoff via `coder/retry`.
- `dialRelay` drops the `codersdk.ExperimentalClient.StreamChat` wrapper
and calls `websocket.Dial` directly so we can capture
`*http.Response.StatusCode` without parsing error strings.
- Adds `RelayDialError` that exposes the HTTP status from `websocket.Dial`
- Modifies retry logic: 401/403 tear the stream down immediately, 5xx/network/timeouts retry
then tear down on cap. Outer stream closes cleanly so the browser SDK
reconnects with a fresh cookie.
- Retry state resets on successful dial and on target-worker change, not
on every `closeRelay()`.
> 🤖 Generated by Coder Agents.
- Moves `coderd/chatd/`, `coderd/gitsync/`, `enterprise/coderd/chatd/`
under `x/` parent directories to signal instability
- Adds `Experimental:` glue code comments in `coderd/coderd.go`
> 🤖 This PR was created with the help of Coder Agents, and was
reviewed by my human. 🧑💻
Kyle Carberry