Follow-up to #26862 ("remove direct chat routing"), which collapsed the
routing discriminated union into a single `aiGatewayModelRoute` but left
a one-path dispatch shim behind in `model_routing.go`.
Removes
`resolveModelRouteForConfig`/`resolveModelRouteForProviderType`/`newModel`
wrapper functions that did nothing but call their `*AIGateway*`
counterparts, and renames the `*AIGateway*` targets to take over those
names directly. Also collapses a redundant if/else in
`title_override.go` where both branches called the same function with
the same effective argument, and has `chatutil.NormalizedStringPointer`
delegate to the existing `coderd/util/strings.EmptyToNil` instead of
reimplementing empty-string-to-nil logic.
No behavior change.
<details>
<summary>Investigation notes / decision log</summary>
Two independent read-only investigations were run over `coderd/x/chatd`
looking for cleanup opportunities following #26862: one focused on
residue from that PR specifically, one a general over-engineering pass
on the whole package. Both independently converged on the
`model_routing.go` shim as the top finding (verified zero divergent call
sites).
Other candidates considered and explicitly deferred/rejected for this
PR:
- Renaming away the vestigial `AIGateway` prefix package-wide:
cosmetic-only, touches many call sites, skipped.
- Inlining the `chatcost` subpackage into `chatd`: unrelated to #26862,
skipped.
- Deleting the deprecated `AIGatewayRoutingEnabled` deployment flag:
confirmed dead/no-op, but intentionally kept as a back-compat shim per
#26862; removal should follow the same deprecation cadence as other
deprecated deployment options, as a separate, differently-timed change.
- Folding `chatutil` entirely into `chatprovider`/`chatopenai`:
`NormalizedStringPointer` overlapped with
`coderd/util/strings.EmptyToNil` (now reused), but `NormalizedEnumValue`
has no equivalent elsewhere in the repo and still has 2 real call sites,
so the package stays.
</details>
---
Generated by Coder Agents on behalf of @johnstcn.
Extracts OpenAI-specific logic from `coderd/x/chatd` into
`coderd/x/chatd/chatopenai` so the main chat path no longer references
`fantasyopenai` directly for chain mode info, response IDs, web search
tooling, or option mapping.
Structural refactor. The only deliberate behavioral narrowing is
consolidating Responses store checks and related keyed option or
metadata access on `opts[fantasyopenai.Name]`. That is documented by
`TestIsResponsesStoreEnabledIgnoresMalformedNonOpenAIKey` and is
unreachable in production where Responses options always live under
`fantasyopenai.Name`.
Summary:
- Moves OpenAI Responses chain mode info, response ID helpers, web
search tool construction, and provider option conversion into
`chatopenai`.
- Keeps Anthropic, Google, OpenRouter, and Vercel provider branches as
thin, existing code paths.
- `chatopenai` only imports `chatprompt` from chatd subpackages. It does
not import `chatd`, `chatloop`, `chatprovider`, or `chaterror`.
- Follow-up review fixes align helper names, keyed provider option
access, map cloning behavior, and PR documentation with the extracted
package boundary.
- Final sweep trims unused chain-mode state, removes a duplicate
store-check test case, drops an unused provider-tool parameter, and
shares the chat-message test helper through `chattest`.
> Mux is updating this PR on Mike's behalf.
Cian Johnston