docs: add QVAC local provider

packages/web/src/content/docs/providers.mdx

@@ -1796,6 +1796,85 @@ OpenCode Zen is a list of tested and verified models provided by the OpenCode te
 
 ---
 
+### QVAC
+
+You can configure opencode to use local models through [QVAC](https://qvac.com), an open-source runtime for local-first, peer-to-peer AI. QVAC exposes an OpenAI-compatible HTTP server via `qvac serve openai`, and the [`@qvac/ai-sdk-provider`](https://www.npmjs.com/package/@qvac/ai-sdk-provider) package wraps it as a branded provider.
+
+:::tip
+Once QVAC lands in [models.dev](https://models.dev), it appears automatically in the `/connect` list — the manual config below is the explicit equivalent and is useful for pinning models and context limits.
+:::
+
+First, install [`@qvac/cli`](https://www.npmjs.com/package/@qvac/cli) and start a server. Preload the model alias you reference in `opencode.json`; QVAC queues same-model completion requests, so opencode's background title, summary, and compaction calls can share the same local model instead of requiring a second model file.
+
+```json title="qvac.config.json"
+{
+  "serve": {
+    "models": {
+      "gpt-oss-20b": {
+        "model": "GPT_OSS_20B_INST_Q4_K_M",
+        "preload": true,
+        "config": {
+          "ctx_size": 32768
+        }
+      }
+    }
+  }
+}
+```
+
+```bash
+npm i -g @qvac/cli
+qvac serve openai
+```
+
+Then point opencode at it:
+
+```json title="opencode.json" "qvac" {5, 6, 8, 11-12, 18, 25-26}
+{
+  "$schema": "https://opencode.ai/config.json",
+  "provider": {
+    "qvac": {
+      "npm": "@qvac/ai-sdk-provider",
+      "name": "QVAC (local)",
+      "options": {
+        "baseURL": "http://127.0.0.1:11434/v1",
+        "apiKey": "qvac"
+      },
+      "models": {
+        "gpt-oss-20b": {
+          "name": "GPT-OSS 20B (local)",
+          "limit": {
+            "context": 32768,
+            "output": 8192
+          }
+        }
+      }
+    }
+  },
+  "model": "qvac/gpt-oss-20b",
+  "small_model": "qvac/gpt-oss-20b"
+}
+```
+
+In this example:
+
+- `qvac` is the custom provider ID. This can be any string you want.
+- `npm` specifies the package to use for this provider — `@qvac/ai-sdk-provider`, the branded QVAC wrapper around `@ai-sdk/openai-compatible`.
+- `options.baseURL` is the endpoint for your local `qvac serve` (set this to match your serve port). Note that `qvac serve openai` defaults to port `11434` — the same default as Ollama. If you run both, pass `--port` to one of them and update `baseURL` to match.
+- `options.apiKey` can be any non-empty string — `qvac serve` does not validate it, but some clients refuse to send a request without an `Authorization` header.
+- The model ID (`gpt-oss-20b`) must match the **serve alias** in `qvac.config.json` — that alias is what the provider sends as the OpenAI `model` field.
+- `model` is the main chat model; `small_model` is the model opencode uses for titles, summarization, and compaction. Pointing both at the same QVAC alias is supported; if you want those utility calls to avoid waiting behind a long chat response, add a second lighter model alias and point `small_model` at it.
+
+:::note
+QVAC's LLM `ctx_size` defaults to 1024 tokens — too small for an agent's tool definitions and system prompt. Set it explicitly in `qvac.config.json`, and set `reasoning_budget: 0` for reasoning-tuned models such as Qwen3 if you want to suppress `<think>` blocks that opencode would otherwise render verbatim.
+:::
+
+:::tip
+Local tool-calling quality is bounded by the model. Small Qwen3 Instruct models are a fast, low-footprint starting point but won't reliably **invoke tools**; for real agent workflows, use a larger agent-tuned model such as `gpt-oss-20b`.
+:::
+
+---
+
 ### SAP AI Core
 
 SAP AI Core provides access to 40+ models from OpenAI, Anthropic, Google, Amazon, Meta, Mistral, and AI21 through a unified platform.