Removes OpenAI Responses "chain mode" from chatd. Closes CODAGT-445.
- Deletes `chatopenai/responses.go` (chain detection, activation, prompt filtering, response ID extraction) and its tests.
- Deletes the `ChainBroken` classification in `chaterror` and the chatloop retry bookkeeping that disabled chain mode mid-generation.
- Drops the `chain_broken` label from the `coderd_chatd_stream_retries_total` metric.
- Stops reading and writing `chat_messages.provider_response_id`
- Deletes the dead `ClearChatMessageProviderResponseIDsByChatID` query. Dropping the column is a follow-up migration.
- Deletes three chatloop hooks no caller sets (`ReloadMessages`, `DisableChainMode`, `PrepareMessages`), the dead `const AgentChatContextSentinelPath`, and stale chain-mode comments.
🤖 Generated by Coder Agents on behalf of @johnstcn.
The provider type already lives authoritatively in ai_providers.type,
reachable on every active row through ai_provider_id, which the
chat_model_configs_ai_provider_required_when_active CHECK makes
mandatory. The stored provider string was a denormalized copy the system
kept in sync with a startup backfill and no longer needs.
Every surface now derives provider type from the linked ai_providers
row. Telemetry is the one exception: it keeps emitting provider, now
sourced from ai_providers.type via a JOIN, so the BigQuery column and the
Nexus dashboards that read it are unaffected. The experimental HTTP/SDK
response drops provider and makes ai_provider_id required, since those
endpoints return only active configs; consumers resolve provider type
from ai_provider_id and the AI providers listing.
This ships in a single release with no compatibility window: production
reads the table via SELECT *, so a pre-drop binary fails config reads the
moment the column is gone. Operators must scale to zero before upgrading,
and there is no rollback.
Closes CODAGT-599
- Adds chat-related dbgen generators covering defaults, overrides, and message field mapping.
- Replaces raw single-row chat, message, provider, and model-config setup in tests with dbgen helpers.
- Simplifies chat seed helpers after moving fixture setup into dbgen.
> Generated with [Coder Agents](https://coder.com/agents).
Cian Johnston