KB: adding LLM vendors

kb/KB.md

@@ -22,6 +22,7 @@ Architecture and system documentation is available in the `/kb/` knowledge base,
 #### Core Platform Systems
 - **[app-routing.md](systems/app-routing.md)** - Next.js routing, provider stack, and display state hierarchy
 - **[LLM-parameters-system.md](systems/LLM-parameters-system.md)** - Language model parameter flow across the system
+- **[LLM-vendor-integration.md](modules/LLM-vendor-integration.md)** - Adding new LLM providers
 
 ### KB Guidelines
 

kb/modules/LLM-vendor-integration.md

@@ -0,0 +1,126 @@
+# LLM Vendor Integration Guide
+
+How to add support for new LLM providers in Big-AGI. There are two integration paths, and
+the dynamic backend path is strongly preferred for new vendors.
+
+## Integration Paths
+
+### Path 1: Dynamic Backend (preferred)
+
+For any provider with an **OpenAI-compatible API** (which is nearly all new providers).
+
+**Surface area**: 1-2 files, no UI changes, no registry changes.
+
+A dynamic backend provides:
+- Hostname-based auto-detection when the user adds the provider's API URL
+- Automatic model list parsing with vendor-specific metadata (pricing, context windows, capabilities)
+- Zero UI code - uses the existing "Custom OpenAI-compatible" service setup
+
+**Files touched**:
+- `src/modules/llms/server/openai/models/{vendor}.models.ts` (required) - model definitions + hostname heuristic
+- `src/modules/llms/server/openai/wiretypes/{vendor}.wiretypes.ts` (optional) - Zod schemas for vendor-specific wire format
+- `src/modules/llms/server/listModels.dispatch.ts` - add heuristic to the detection chain (2 lines)
+
+**What the model file must export**:
+```typescript
+// 1. Hostname heuristic - returns true when the user's API URL matches this vendor
+export function vendorHeuristic(hostname: string): boolean {
+  return hostname.includes('.vendor-domain.com');
+}
+
+// 2. Model converter - transforms vendor's /v1/models response to ModelDescriptionSchema[]
+export function vendorModelsToModelDescriptions(wireModels: unknown): ModelDescriptionSchema[] {
+  // Parse wire format, map to ModelDescriptionSchema with:
+  // - id, label, description
+  // - contextWindow, maxCompletionTokens
+  // - interfaces (Chat, Vision, Fn, Reasoning, etc.)
+  // - chatPrice (input/output per token)
+  // - parameterSpecs (temperature, etc.)
+}
+```
+
+**Existing examples**: `novita.models.ts`, `chutesai.models.ts`, `fireworksai.models.ts`
+
+MUST also provide the updated vendor icon like other icons in `src/common/components/icons/vendors/`.
+Make sure all the information is available if in the future we want to promote those to full registered vendors.
+
+### Path 2: Registered Vendor (heavyweight, discouraged for new providers)
+
+Full first-class integration with dedicated UI, own dialect, and registry entry. Reserved for
+providers with **non-OpenAI protocols** (Anthropic, Gemini, Ollama) or providers with enough
+user demand to warrant a dedicated setup flow.
+
+**Surface area**: 5+ files across 3 directories.
+
+**Files touched**:
+- `src/modules/llms/vendors/{vendor}/{vendor}.vendor.ts` - IModelVendor implementation
+- `src/modules/llms/vendors/{vendor}/{VendorName}ServiceSetup.tsx` - React UI setup component
+- `src/modules/llms/vendors/vendors.registry.ts` - registry entry + ModelVendorId union
+- `src/modules/llms/server/openai/models/{vendor}.models.ts` - model definitions
+- `src/modules/llms/server/listModels.dispatch.ts` - dispatch case
+- Possibly server protocol adapter if not OpenAI-compatible
+- Possibly more files, e.g. wires, etc.
+- See existing providers and commits that added them for full scope
+
+**When to use this path**: Only when the provider has a meaningfully different API protocol
+(not OpenAI-compatible), or when there is significant user demand AND the provider offers
+unique capabilities that benefit from dedicated UI (e.g., Ollama's local model management).
+
+When using this path, please add links to upstream documentation. Make sure all constants
+are correctly handled everywhere, especially for provider-based switches.
+
+## Decision Criteria
+
+| Question | Dynamic | Registered |
+|----------|---------|------------|
+| OpenAI-compatible API? | Yes - use dynamic | Only if not OAI-compatible |
+| Needs custom auth UI? | No - uses generic fields | Yes - custom setup form |
+| Unique protocol? | No | Yes (Anthropic, Gemini, Ollama) |
+| User demand level | Any | High + sustained |
+| Maintenance burden | Minimal | Significant (5+ files) |
+
+## For External Contributors / Vendor Requests
+
+When vendors or community members request integration via GitHub issues:
+
+1. **Point them to the dynamic backend path** - it's faster to implement, review, and maintain
+2. **Requirements for a dynamic backend PR**:
+   - Model file with heuristic + converter exporting `ModelDescriptionSchema[]`
+   - Wire types if the vendor's `/v1/models` response has non-standard fields
+   - Vendor icon (SVG preferred) in `src/common/components/icons/vendors/`
+   - Two-line addition to the heuristic chain in `listModels.dispatch.ts`
+3. **Do not accept**: New registered vendors for OpenAI-compatible providers. The maintenance
+   cost of a full vendor (UI component, registry entry, dispatch case) is not justified when
+   dynamic detection achieves the same result with a fraction of the code.
+
+## Architecture Notes
+
+### How Dynamic Detection Works
+
+In `listModels.dispatch.ts`, the `case 'openai':` handler:
+1. Fetches `/v1/models` from the user-provided API host
+2. Runs the hostname through a chain of heuristics (in order)
+3. First matching heuristic's converter is used to parse models
+4. Falls back to stock OpenAI parsing if no heuristic matches
+
+### Hostname Security
+
+Hostname matching uses `llmsHostnameMatches()` from `openai.access.ts` which parses the
+URL properly to prevent DNS spoofing. Always use `.includes()` on the parsed hostname,
+never on the raw URL string.
+
+### Key Types
+
+- `ModelDescriptionSchema` (`llm.server.types.ts`) - output type for all model converters
+- `DModelInterfaceV1` (`llms.types.ts`) - capability flags (Chat, Vision, Fn, Reasoning, etc.)
+- `IModelVendor` (`vendors/IModelVendor.ts`) - interface for registered vendors only
+- `ManualMappings` / `KnownModel` (`models.mappings.ts`) - server-side model patches
+
+### File Locations
+
+- Dynamic backends: `src/modules/llms/server/openai/models/`
+- Wire types: `src/modules/llms/server/openai/wiretypes/`
+- Dispatch: `src/modules/llms/server/listModels.dispatch.ts`
+- Registered vendors: `src/modules/llms/vendors/*/`
+- Vendor icons: `src/common/components/icons/vendors/`
+- Type definitions: `src/modules/llms/server/llm.server.types.ts`