fix(providers): minimax-m3 collapses manual thinking.type:enabled to adaptive (#12132) (#13249)

Merged as part of the 39-PR owner batch of 2026-09-11, validated as a unit.

Boarded into one consolidated worktree cut from `release/v3.8.51` with the other 38 — zero conflicts between them.

- ESLint over every changed file: no errors (the only finding was one suppression entry the batch emptied, pruned on #13243)
- `typecheck:core` clean; `check:dashboard-typecheck` OK (206 pre-existing, within baseline); `check:changelog-integrity` OK
- complexity 2821 / baseline 3218 and cognitive-complexity 1272 / baseline 1437 — both under baseline
- 256 assertions green: 246 under node:test and 10 under vitest, which is where `tests/unit/**/*.test.tsx` actually runs
- `check-file-size`: `chatCore.ts` rebaselined 6144 → 6146 for #13278 and #13276, annotated and landed on #13243

⚠️ base-red inherited: #12732 — the provider count (356 in the docs vs the 358 the modules define) and `open-sse/utils/stream.ts` at 3115 > frozen 3098 both reproduce on the pure tip with zero contribution from this batch.

changelog.d/fixes/12132-minimax-m3-adaptive-thinking.md

@@ -0,0 +1 @@
+- fix(providers): minimax-m3 now collapses manual thinking.type:"enabled" to adaptive, preventing upstream 400 (2013) (#12132)

src/shared/constants/modelSpecs.ts

@@ -733,12 +733,16 @@ export const MODEL_SPECS: Record<string, ModelSpec> = {
   // ── MiniMax M3 (1M context, 512K max output) ─────────────────────
   // max output verified against MiniMax docs / OpenRouter / Artificial
   // Analysis (Nov 2025 launch): 1,048,576-token context, up to 512K output.
+  // Adaptive-thinking-only: MiniMax rejects manual budget_tokens /
+  // thinking.type:"enabled" with 400 (2013) — "invalid thinking.type:
+  // \"enabled\" (allowed: adaptive, disabled)" (#12132).
   "minimax-m3": {
     maxOutputTokens: 512000,
     contextWindow: 1048576,
     thinkingBudgetCap: 32768,
     supportsThinking: true,
     supportsTools: true,
+    adaptiveThinkingOnly: true,
     aliases: ["MiniMax-M3", "MiniMaxAI/MiniMax-M3"],
   },
 

tests/unit/minimax-m3-adaptive-thinking-12132.test.ts

@@ -0,0 +1,48 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { isAdaptiveThinkingOnly } from "@/shared/constants/modelSpecs.ts";
+import { normalizeClaudeAdaptiveThinking } from "@omniroute/open-sse/services/claudeAdaptiveThinking.ts";
+
+// Issue #12132: MiniMax M3 rejects thinking.type:"enabled" with 400 (2013)
+// ("invalid thinking.type: \"enabled\" (allowed: adaptive, disabled)"), but the
+// modelSpecs entry for minimax-m3 was never given `adaptiveThinkingOnly: true`
+// (the change #9155 proposed and claimed to have landed). Because every
+// normalization site that would collapse `enabled` -> `adaptive` gates on
+// `isAdaptiveThinkingOnly()`, a manual thinking.type:"enabled" request that
+// resolves to MiniMax M3 (via either the `minimax` or `minimax-cn` provider,
+// since both alias to the same spec entry) was forwarded unchanged and
+// upstream 400s.
+
+test("minimax-m3 is flagged adaptiveThinkingOnly so manual thinking.type is collapsed", () => {
+  assert.equal(
+    isAdaptiveThinkingOnly("minimax-m3"),
+    true,
+    "minimax-m3 modelSpec is missing adaptiveThinkingOnly: true"
+  );
+  assert.equal(
+    isAdaptiveThinkingOnly("MiniMax-M3"),
+    true,
+    "MiniMax-M3 alias must resolve to the same adaptive-thinking-only spec"
+  );
+});
+
+test("normalizeClaudeAdaptiveThinking collapses enabled->adaptive for MiniMax M3", () => {
+  const body = {
+    thinking: { type: "enabled", budget_tokens: 20000 },
+    output_config: { effort: "max" },
+  };
+
+  const result = normalizeClaudeAdaptiveThinking(body, "MiniMax-M3");
+
+  assert.equal(
+    (result.thinking as Record<string, unknown>).type,
+    "adaptive",
+    "thinking.type:\"enabled\" must be collapsed to \"adaptive\" for MiniMax M3, " +
+      "otherwise upstream rejects it with 400 (2013)"
+  );
+  assert.equal(
+    (result.thinking as Record<string, unknown>).budget_tokens,
+    undefined,
+    "budget_tokens must be dropped once thinking is collapsed to adaptive"
+  );
+});