refactor(providers): one record per provider, one place for the key-and-URL decision (#988)

Every fact about a provider lives in one record in lib/providers.ts (SDK kind,
credential kind, env var prefix, default URL, picker group, four-language
notes, and a short model list for the six providers that cannot list models).
The thirteen tables keyed by provider name are gone. resolveEndpoint decides
whose key a call uses and where it goes; usesServerCredentials reads its
answer instead of mirroring getAIModel's branches; serverCredentialError holds
the server credential check once. The UI, the connection test and the routes
read the record's credential and sdk fields instead of comparing provider
names (44 such checks before, 6 after, in the admin panel's fixed-variable
branches).

Intended behavior changes: providers that can list their models have no
hand-written list; the settings dialog fetches the live list in the background
once credentials are entered for a provider without models and offers it
behind "Browse models". Azure has no placeholder default URL (old entries that
hold it still count as unset); the base URL field of Azure and of the new
"custom" OpenAI-compatible preset (CUSTOM_API_KEY, CUSTOM_BASE_URL) is
labelled required. The connection test answers 400 for an unknown provider
name; prototype names are refused everywhere. Provider lists in error messages
and the admin "add provider" dropdown follow the picker's order.

Also fixed, from before the refactor: the redirect guard drops x-access-code
on cross-origin redirects, and edgeOneEndpoint accepts the Origin header only
when it matches Host or X-Forwarded-Host.

Verification: a behavior snapshot of getAIModel's SDK factory calls and the
quota functions over 25 providers, 22 client override shapes and 9 server
environments (5843 rows), recorded on the old code and unchanged apart from
the intended changes; 752 unit tests, 65 provider e2e tests, tsc, biome,
next build. Reviewed by five models from one brief; their findings and the
resulting fixes are recorded in docs/plans/2026-10-provider-refactor.md.

components/provider-credentials-fields.tsx

@@ -2,6 +2,7 @@
 
 import { ChevronRight, Key, Link2, Tag } from "lucide-react"
 import { type ReactNode, useState } from "react"
+import { useLocale } from "@/components/canvas/locale-context"
 import { Input } from "@/components/ui/input"
 import { Label } from "@/components/ui/label"
 import {
@@ -13,13 +14,8 @@ import {
 } from "@/components/ui/select"
 import { useDictionary } from "@/hooks/use-dictionary"
 import { formatMessage } from "@/lib/i18n/utils"
-import { OPTIONS_OPEN } from "@/lib/provider-setup"
-import {
-    chatRequestUrl,
-    normalizeBaseUrl,
-    PROVIDER_INFO,
-    type ProviderName,
-} from "@/lib/types/model-config"
+import { PROVIDERS, type ProviderName } from "@/lib/providers"
+import { chatRequestUrl, normalizeBaseUrl } from "@/lib/types/model-config"
 import { cn } from "@/lib/utils"
 
 // Logical secret field. The caller owns the actual input — plaintext for the
@@ -94,10 +90,15 @@ export function ProviderCredentialsFields({
     sessionTokenInput,
 }: ProviderCredentialsFieldsProps) {
     const dict = useDictionary()
-    const info = PROVIDER_INFO[provider]
-    const baseUrlLabel = formatMessage(dict.modelConfig.baseUrlWithExample, {
-        example: info.defaultBaseUrl || "https://api.example.com/v1",
-    })
+    const locale = useLocale()
+    const info = PROVIDERS[provider]
+    // A key-only provider without a default URL (Azure, custom) needs one
+    const baseUrlLabel =
+        info.credential === "apiKey" && !info.defaultBaseUrl
+            ? dict.modelConfig.baseUrlRequired
+            : formatMessage(dict.modelConfig.baseUrlWithExample, {
+                  example: info.defaultBaseUrl || "https://api.example.com/v1",
+              })
     const requestUrl = baseUrl ? chatRequestUrl(provider, baseUrl) : null
     // Open when it holds something the user set, or for a provider whose
     // base URL usually needs changing or comes with a hint
@@ -105,7 +106,7 @@ export function ProviderCredentialsFields({
         () =>
             !!name ||
             (!!baseUrl && baseUrl !== info.defaultBaseUrl) ||
-            OPTIONS_OPEN.includes(provider),
+            !!info.optionsOpen,
     )
     // Bedrock: the way that is filled in (an API key is used first when both
     // are, as the server does), else the one shown last, so emptying the
@@ -199,7 +200,8 @@ export function ProviderCredentialsFields({
                 >
                     <Key className="h-3.5 w-3.5 text-muted-foreground" />
                     {dict.modelConfig.apiKey}
-                    {provider === "ollama" && ` ${dict.modelConfig.optional}`}
+                    {info.credential === "optionalKey" &&
+                        ` ${dict.modelConfig.optional}`}
                 </Label>
                 {info.apiKeyUrl && (
                     <a
@@ -248,26 +250,21 @@ export function ProviderCredentialsFields({
                     })}
                 </p>
             )}
-            {provider === "minimax" && (
+            {info.baseUrlHint && (
                 <p className="text-xs text-muted-foreground">
-                    {dict.modelConfig.minimaxBaseUrlHint}
-                </p>
-            )}
-            {provider === "mimo" && (
-                <p className="text-xs text-muted-foreground">
-                    {dict.modelConfig.mimoBaseUrlHint}
+                    {info.baseUrlHint[locale]}
                 </p>
             )}
         </div>
     )
 
-    // EdgeOne needs no credentials
-    if (provider === "edgeone") return null
+    // A provider without credentials (EdgeOne) has no fields
+    if (info.credential === "none") return null
 
     if (settingsLayout) {
         return (
             <div className="space-y-4">
-                {provider === "bedrock" ? (
+                {info.credential === "aws" ? (
                     <>
                         {/* Buttons, not radios: arrow keys would empty
                             secrets without a deliberate press */}
@@ -393,7 +390,7 @@ export function ProviderCredentialsFields({
                         )}
                         {regionField}
                     </>
-                ) : provider === "vertexai" ? (
+                ) : info.credential === "vertexKey" ? (
                     <div className="space-y-2">
                         <Label
                             htmlFor="vertex-api-key"
@@ -423,14 +420,14 @@ export function ProviderCredentialsFields({
                                 optionsOpen && "rotate-90",
                             )}
                         />
-                        {provider === "bedrock"
+                        {info.credential === "aws"
                             ? dict.modelConfig.moreOptionsName
                             : dict.modelConfig.moreOptions}
                     </button>
                     {optionsOpen && (
                         <>
-                            {provider !== "bedrock" &&
-                                (provider === "vertexai"
+                            {info.credential !== "aws" &&
+                                (info.credential === "vertexKey"
                                     ? vertexBaseUrlField
                                     : baseUrlField)}
                             {nameField}
@@ -445,7 +442,7 @@ export function ProviderCredentialsFields({
         <div className="space-y-5">
             {nameField}
 
-            {provider === "bedrock" ? (
+            {info.credential === "aws" ? (
                 <>
                     {/* AWS Access Key ID */}
                     <div className="space-y-2">
@@ -479,7 +476,7 @@ export function ProviderCredentialsFields({
 
                     {regionField}
                 </>
-            ) : provider === "vertexai" ? (
+            ) : info.credential === "vertexKey" ? (
                 <>
                     {/* Vertex AI API Key (Express Mode) */}
                     <div className="space-y-2">