refactor: consolidate experimental chats API types (#23143)

## Summary

Consolidates three areas of type duplication in the experimental chats
API:

### 1. Merge archive/unarchive into `PATCH /{chat}`
- **Before:** `POST /{chat}/archive` + `POST /{chat}/unarchive` (two
endpoints, two handlers with mirrored logic)
- **After:** `PATCH /{chat}` accepting `{ "archived": true/false }` via
`UpdateChatRequest`
- Removes one endpoint and ~30 lines of duplicated handler code

### 2. Collapse identical request/response prompt types
- `ChatSystemPromptResponse` + `UpdateChatSystemPromptRequest` →
`ChatSystemPrompt`
- `UserChatCustomPromptResponse` + `UpdateUserChatCustomPromptRequest` →
`UserChatCustomPrompt`
- These pairs were field-for-field identical (single string field)

### 3. Merge duplicate reasoning options types
- `ChatModelOpenRouterReasoningOptions` +
`ChatModelVercelReasoningOptions` → `ChatModelReasoningOptions`
- Same 4 fields, same types — only field ordering and enum value sets
differed
- Unified type uses the superset of enum values

### Files changed
- `codersdk/chats.go` — SDK types and client methods
- `coderd/chats.go` — Handler consolidation
- `coderd/coderd.go` — Route change
- `coderd/chats_test.go` — Test updates
- `site/src/api/api.ts` — Frontend API client
- `site/src/api/queries/chats.ts` — Query mutations
- `site/src/api/queries/chats.test.ts` — Test mocks
- `site/src/pages/AgentsPage/AgentsPage.tsx` — Call site
- Generated files (`typesGenerated.ts`,
`chatModelOptionsGenerated.json`)

### Testing
- All Go tests pass (`TestArchiveChat`, `TestUnarchiveChat`,
`TestChatSystemPrompt`)
- All frontend tests pass (31/31 in `chats.test.ts`)

codersdk/chats.go

@@ -245,7 +245,8 @@ type CreateChatRequest struct {
 
 // UpdateChatRequest is the request to update a chat.
 type UpdateChatRequest struct {
-	Title string `json:"title"`
+	Title    *string `json:"title,omitempty"`
+	Archived *bool   `json:"archived,omitempty"`
 }
 
 // CreateChatMessageRequest is the request to add a message to a chat.
@@ -307,25 +308,15 @@ type ChatModelsResponse struct {
 	Providers []ChatModelProvider `json:"providers"`
 }
 
-// ChatSystemPromptResponse is the response for getting the chat system prompt.
-type ChatSystemPromptResponse struct {
+// ChatSystemPrompt is the request and response body for the chat
+// system prompt configuration endpoint.
+type ChatSystemPrompt struct {
 	SystemPrompt string `json:"system_prompt"`
 }
 
-// UpdateChatSystemPromptRequest is the request to update the chat system prompt.
-type UpdateChatSystemPromptRequest struct {
-	SystemPrompt string `json:"system_prompt"`
-}
-
-// UserChatCustomPromptResponse is the response for getting a user's
-// custom chat prompt.
-type UserChatCustomPromptResponse struct {
-	CustomPrompt string `json:"custom_prompt"`
-}
-
-// UpdateUserChatCustomPromptRequest is the request to update a user's
-// custom chat prompt.
-type UpdateUserChatCustomPromptRequest struct {
+// UserChatCustomPrompt is the request and response body for the
+// user chat custom prompt configuration endpoint.
+type UserChatCustomPrompt struct {
 	CustomPrompt string `json:"custom_prompt"`
 }
 
@@ -466,12 +457,13 @@ type ChatModelOpenAICompatProviderOptions struct {
 	ReasoningEffort *string `json:"reasoning_effort,omitempty" description:"Controls the level of reasoning effort" enum:"none,minimal,low,medium,high,xhigh"`
 }
 
-// ChatModelOpenRouterReasoningOptions configures OpenRouter reasoning behavior.
-type ChatModelOpenRouterReasoningOptions struct {
+// ChatModelReasoningOptions configures reasoning behavior for model
+// providers that support it.
+type ChatModelReasoningOptions struct {
 	Enabled   *bool   `json:"enabled,omitempty" description:"Whether reasoning is enabled"`
 	Exclude   *bool   `json:"exclude,omitempty" description:"Whether to exclude reasoning content from the response"`
 	MaxTokens *int64  `json:"max_tokens,omitempty" description:"Maximum number of tokens for reasoning output"`
-	Effort    *string `json:"effort,omitempty" description:"Controls the level of reasoning effort" enum:"low,medium,high"`
+	Effort    *string `json:"effort,omitempty" description:"Controls the level of reasoning effort" enum:"none,minimal,low,medium,high,xhigh"`
 }
 
 // ChatModelOpenRouterProvider configures OpenRouter routing preferences.
@@ -488,22 +480,14 @@ type ChatModelOpenRouterProvider struct {
 
 // ChatModelOpenRouterProviderOptions configures OpenRouter provider behavior.
 type ChatModelOpenRouterProviderOptions struct {
-	Reasoning         *ChatModelOpenRouterReasoningOptions `json:"reasoning,omitempty" description:"Configuration for reasoning behavior"`
-	ExtraBody         map[string]any                       `json:"extra_body,omitempty" description:"Additional fields to include in the request body" hidden:"true"`
-	IncludeUsage      *bool                                `json:"include_usage,omitempty" description:"Whether to include token usage information in the response" hidden:"true"`
-	LogitBias         map[string]int64                     `json:"logit_bias,omitempty" description:"Token IDs mapped to bias values from -100 to 100" hidden:"true"`
-	LogProbs          *bool                                `json:"log_probs,omitempty" description:"Whether to return log probabilities of output tokens" hidden:"true"`
-	ParallelToolCalls *bool                                `json:"parallel_tool_calls,omitempty" description:"Whether the model may make multiple tool calls in parallel"`
-	User              *string                              `json:"user,omitempty" description:"Unique identifier for the end user for abuse monitoring" hidden:"true"`
-	Provider          *ChatModelOpenRouterProvider         `json:"provider,omitempty" description:"Routing preferences for provider selection" hidden:"true"`
-}
-
-// ChatModelVercelReasoningOptions configures Vercel reasoning behavior.
-type ChatModelVercelReasoningOptions struct {
-	Enabled   *bool   `json:"enabled,omitempty" description:"Whether reasoning is enabled"`
-	MaxTokens *int64  `json:"max_tokens,omitempty" description:"Maximum number of tokens for reasoning output"`
-	Effort    *string `json:"effort,omitempty" description:"Controls the level of reasoning effort" enum:"none,minimal,low,medium,high,xhigh"`
-	Exclude   *bool   `json:"exclude,omitempty" description:"Whether to exclude reasoning content from the response"`
+	Reasoning         *ChatModelReasoningOptions   `json:"reasoning,omitempty" description:"Configuration for reasoning behavior"`
+	ExtraBody         map[string]any               `json:"extra_body,omitempty" description:"Additional fields to include in the request body" hidden:"true"`
+	IncludeUsage      *bool                        `json:"include_usage,omitempty" description:"Whether to include token usage information in the response" hidden:"true"`
+	LogitBias         map[string]int64             `json:"logit_bias,omitempty" description:"Token IDs mapped to bias values from -100 to 100" hidden:"true"`
+	LogProbs          *bool                        `json:"log_probs,omitempty" description:"Whether to return log probabilities of output tokens" hidden:"true"`
+	ParallelToolCalls *bool                        `json:"parallel_tool_calls,omitempty" description:"Whether the model may make multiple tool calls in parallel"`
+	User              *string                      `json:"user,omitempty" description:"Unique identifier for the end user for abuse monitoring" hidden:"true"`
+	Provider          *ChatModelOpenRouterProvider `json:"provider,omitempty" description:"Routing preferences for provider selection" hidden:"true"`
 }
 
 // ChatModelVercelGatewayProviderOptions configures Vercel routing behavior.
@@ -514,7 +498,7 @@ type ChatModelVercelGatewayProviderOptions struct {
 
 // ChatModelVercelProviderOptions configures Vercel provider behavior.
 type ChatModelVercelProviderOptions struct {
-	Reasoning         *ChatModelVercelReasoningOptions       `json:"reasoning,omitempty" description:"Configuration for reasoning behavior"`
+	Reasoning         *ChatModelReasoningOptions             `json:"reasoning,omitempty" description:"Configuration for reasoning behavior"`
 	ProviderOptions   *ChatModelVercelGatewayProviderOptions `json:"providerOptions,omitempty" description:"Gateway routing options for provider selection" hidden:"true"`
 	User              *string                                `json:"user,omitempty" description:"Unique identifier for the end user for abuse monitoring" hidden:"true"`
 	LogitBias         map[string]int64                       `json:"logit_bias,omitempty" description:"Token IDs mapped to bias values from -100 to 100" hidden:"true"`
@@ -1246,21 +1230,21 @@ func (c *Client) GetChatCostUsers(ctx context.Context, opts ChatCostUsersOptions
 }
 
 // GetChatSystemPrompt returns the deployment-wide chat system prompt.
-func (c *Client) GetChatSystemPrompt(ctx context.Context) (ChatSystemPromptResponse, error) {
+func (c *Client) GetChatSystemPrompt(ctx context.Context) (ChatSystemPrompt, error) {
 	res, err := c.Request(ctx, http.MethodGet, "/api/experimental/chats/config/system-prompt", nil)
 	if err != nil {
-		return ChatSystemPromptResponse{}, err
+		return ChatSystemPrompt{}, err
 	}
 	defer res.Body.Close()
 	if res.StatusCode != http.StatusOK {
-		return ChatSystemPromptResponse{}, ReadBodyAsError(res)
+		return ChatSystemPrompt{}, ReadBodyAsError(res)
 	}
-	var resp ChatSystemPromptResponse
+	var resp ChatSystemPrompt
 	return resp, json.NewDecoder(res.Body).Decode(&resp)
 }
 
 // UpdateChatSystemPrompt updates the deployment-wide chat system prompt.
-func (c *Client) UpdateChatSystemPrompt(ctx context.Context, req UpdateChatSystemPromptRequest) error {
+func (c *Client) UpdateChatSystemPrompt(ctx context.Context, req ChatSystemPrompt) error {
 	res, err := c.Request(ctx, http.MethodPut, "/api/experimental/chats/config/system-prompt", req)
 	if err != nil {
 		return err
@@ -1273,30 +1257,30 @@ func (c *Client) UpdateChatSystemPrompt(ctx context.Context, req UpdateChatSyste
 }
 
 // GetUserChatCustomPrompt fetches the user's custom chat prompt.
-func (c *Client) GetUserChatCustomPrompt(ctx context.Context) (UserChatCustomPromptResponse, error) {
+func (c *Client) GetUserChatCustomPrompt(ctx context.Context) (UserChatCustomPrompt, error) {
 	res, err := c.Request(ctx, http.MethodGet, "/api/experimental/chats/config/user-prompt", nil)
 	if err != nil {
-		return UserChatCustomPromptResponse{}, err
+		return UserChatCustomPrompt{}, err
 	}
 	defer res.Body.Close()
 	if res.StatusCode != http.StatusOK {
-		return UserChatCustomPromptResponse{}, ReadBodyAsError(res)
+		return UserChatCustomPrompt{}, ReadBodyAsError(res)
 	}
-	var resp UserChatCustomPromptResponse
+	var resp UserChatCustomPrompt
 	return resp, json.NewDecoder(res.Body).Decode(&resp)
 }
 
 // UpdateUserChatCustomPrompt updates the user's custom chat prompt.
-func (c *Client) UpdateUserChatCustomPrompt(ctx context.Context, req UpdateUserChatCustomPromptRequest) (UserChatCustomPromptResponse, error) {
+func (c *Client) UpdateUserChatCustomPrompt(ctx context.Context, req UserChatCustomPrompt) (UserChatCustomPrompt, error) {
 	res, err := c.Request(ctx, http.MethodPut, "/api/experimental/chats/config/user-prompt", req)
 	if err != nil {
-		return UserChatCustomPromptResponse{}, err
+		return UserChatCustomPrompt{}, err
 	}
 	defer res.Body.Close()
 	if res.StatusCode != http.StatusOK {
-		return UserChatCustomPromptResponse{}, ReadBodyAsError(res)
+		return UserChatCustomPrompt{}, ReadBodyAsError(res)
 	}
-	var resp UserChatCustomPromptResponse
+	var resp UserChatCustomPrompt
 	return resp, json.NewDecoder(res.Body).Decode(&resp)
 }
 
@@ -1499,20 +1483,9 @@ func (c *Client) GetChatMessages(ctx context.Context, chatID uuid.UUID, opts *Ch
 	return resp, json.NewDecoder(res.Body).Decode(&resp)
 }
 
-func (c *Client) ArchiveChat(ctx context.Context, chatID uuid.UUID) error {
-	res, err := c.Request(ctx, http.MethodPost, fmt.Sprintf("/api/experimental/chats/%s/archive", chatID), nil)
-	if err != nil {
-		return err
-	}
-	defer res.Body.Close()
-	if res.StatusCode != http.StatusNoContent {
-		return ReadBodyAsError(res)
-	}
-	return nil
-}
-
-func (c *Client) UnarchiveChat(ctx context.Context, chatID uuid.UUID) error {
-	res, err := c.Request(ctx, http.MethodPost, fmt.Sprintf("/api/experimental/chats/%s/unarchive", chatID), nil)
+// UpdateChat patches a chat resource.
+func (c *Client) UpdateChat(ctx context.Context, chatID uuid.UUID, req UpdateChatRequest) error {
+	res, err := c.Request(ctx, http.MethodPatch, fmt.Sprintf("/api/experimental/chats/%s", chatID), req)
 	if err != nil {
 		return err
 	}