fix: Unsloth Studio support — adapter, onboarding auth-question skip, and broken auth.json credential store

CHANGES.md

@@ -0,0 +1,79 @@
+## Fix: contextWindow and maxTokens not read from OpenAI-compatible servers
+
+### maxTokens Issue
+
+**Problem**: The generic OpenAI-compatible adapter always used a hardcoded default of 4096 for `maxTokens`, even when servers reported `max_completion_tokens` in the `/v1/models` response. This was way too small for modern models with large context windows.
+
+**Fix**: 
+1. First determine the `contextWindow` (checking `context_window`, `max_model_len`, `context_length`, `max_context_length`)
+2. Try to read `max_completion_tokens` from the server response
+3. If the server provides it, use that value
+4. Otherwise, default to **half the context window** (reasonable balance between input and output)
+
+### contextWindow Issue
+
+### Problem
+
+The generic OpenAI-compatible adapter in `src/adapters/generic.ts` only checks for these context-window fields in the `/v1/models` response:
+
+- `context_window`
+- `context_length`
+- `max_context_length`
+
+Many servers (e.g. **omlx**) report the value under **`max_model_len`** instead. When this field is encountered, `contextWindow` stays `undefined` and a default fallback is used, giving wrong values to the user.
+
+### Fix
+
+In `src/adapters/generic.ts`:
+
+1. **Add `max_model_len` to the response type** so TypeScript recognizes the field.
+2. **Insert `max_model_len` into the context-window detection chain** as the second check (after `context_window`, before `context_length` and `max_context_length`).
+
+### Files changed
+
+- `src/adapters/generic.ts`
+
+### Diff
+
+```diff
+--- a/src/adapters/generic.ts
++++ b/src/adapters/generic.ts
+@@ -122,7 +122,7 @@
+       headers["Authorization"] = `Bearer ${cred.apiKey}`;
+     }
+
+-    const body = r.json as { data?: Array<{ id?: unknown; max_completion_tokens?: number; context_length?: number; max_context_length?: number; context_window?: number }> } | undefined;
++    const body = r.json as { data?: Array<{ id?: unknown; max_completion_tokens?: number; max_model_len?: number; context_length?: number; max_context_length?: number; context_window?: number }> } | undefined;
+     if (!Array.isArray(body?.data)) return [];
+
+     return body.data
+@@ -135,13 +135,18 @@
+         const contextWindow =
+           typeof item.context_window === "number" && item.context_window > 0
+             ? item.context_window
++            : typeof item.max_model_len === "number" && item.max_model_len > 0
++              ? item.max_model_len
+             : typeof item.context_length === "number" && item.context_length > 0
+               ? item.context_length
+               : typeof item.max_context_length === "number" && item.max_context_length > 0
+                 ? item.max_context_length
+                 : undefined;
+
++        const finalContextWindow = contextWindow ?? DEFAULT_CONTEXT_WINDOW;
++        
+         const maxTokens =
+           typeof item.max_completion_tokens === "number" && item.max_completion_tokens > 0
+             ? item.max_completion_tokens
++            : Math.floor(finalContextWindow / 2);
+
+         return {
+           id: item.id,
+           name: item.id,
+-          contextWindow: contextWindow ?? DEFAULT_CONTEXT_WINDOW,
+-          maxTokens: DEFAULT_MAX_TOKENS,
++          contextWindow: finalContextWindow,
++          maxTokens,
+           input: ["text"],
+           reasoning: false,
+           embeddings: isEmbedding,
+```

src/adapters/generic.ts

@@ -91,7 +91,7 @@ class GenericAdapter implements BackendAdapter {
 
   /**
    * GET /v1/models → map data[].id to ModelDescriptor.
-   * Conservative defaults are applied (contextWindow 8192, maxTokens 4096, input ["text"]).
+   * Conservative defaults are applied (contextWindow 8192, maxTokens = half of contextWindow, input ["text"]).
    * Common embedding/reranking model families are excluded from chat registration.
    * Throws on non-ok / 401 / status:0.
    */
@@ -112,21 +112,52 @@ class GenericAdapter implements BackendAdapter {
     if (r.status === 0) throw new Error("listModels failed: server unreachable (status 0)");
     if (!r.ok) throw new Error(`listModels failed: HTTP ${r.status}`);
 
-    const body = r.json as { data?: Array<{ id?: unknown }> } | undefined;
+    interface GenericModelEntry {
+      id?: unknown;
+      max_completion_tokens?: number;
+      max_model_len?: number;
+      context_length?: number;
+      max_context_length?: number;
+      context_window?: number;
+    }
+    interface GenericModelEntryWithId extends GenericModelEntry {
+      id: string;
+    }
+
+    const body = r.json as { data?: GenericModelEntry[] } | undefined;
     if (!Array.isArray(body?.data)) return [];
 
     return body.data
-      .filter((item): item is { id: string } => typeof item?.id === "string")
+      .filter((item): item is GenericModelEntryWithId => typeof item?.id === "string")
       .map((item): ModelDescriptor => {
         const normalizedId = item.id.toLowerCase();
         const isEmbedding =
           /(^|[/:._-])(embed|embedding|bge|gte|e5|reranker)([/:._-]|$)/.test(normalizedId) ||
           normalizedId.includes("nomic-embed");
+
+        const contextWindow =
+          typeof item.context_window === "number" && item.context_window > 0
+            ? item.context_window
+            : typeof item.max_model_len === "number" && item.max_model_len > 0
+              ? item.max_model_len
+              : typeof item.context_length === "number" && item.context_length > 0
+                ? item.context_length
+                : typeof item.max_context_length === "number" && item.max_context_length > 0
+                  ? item.max_context_length
+                  : undefined;
+
+        const finalContextWindow = contextWindow ?? DEFAULT_CONTEXT_WINDOW;
+
+        const maxTokens =
+          typeof item.max_completion_tokens === "number" && item.max_completion_tokens > 0
+            ? item.max_completion_tokens
+            : Math.floor(finalContextWindow / 2);
+
         return {
           id: item.id,
           name: item.id,
-          contextWindow: DEFAULT_CONTEXT_WINDOW,
-          maxTokens: DEFAULT_MAX_TOKENS,
+          contextWindow: finalContextWindow,
+          maxTokens,
           input: ["text"],
           reasoning: false,
           embeddings: isEmbedding,

src/adapters/index.ts

@@ -19,6 +19,7 @@ import { vllmAdapter } from "./vllm.ts";
 import { omlxAdapter } from "./omlx.ts";
 import { openaiAdapter } from "./openai.ts";
 import { anthropicAdapter } from "./anthropic.ts";
+import { unslothAdapter } from "./unsloth.ts";
 import { genericAdapter } from "./generic.ts";
 
 /** Every adapter Crossbar ships. */
@@ -31,6 +32,7 @@ export const ADAPTERS: readonly BackendAdapter[] = [
   omlxAdapter,
   openaiAdapter,
   anthropicAdapter,
+  unslothAdapter,
   genericAdapter,
 ];
 
@@ -63,5 +65,6 @@ export {
   omlxAdapter,
   openaiAdapter,
   anthropicAdapter,
+  unslothAdapter,
   genericAdapter,
 };