diff --git a/README_en.md b/README_en.md
index b409b99..f5f54fb 100644
--- a/README_en.md
+++ b/README_en.md
@@ -83,12 +83,75 @@ vision tool calls the vision API → returns image description
 
 ## Environment Variables
 
-| Variable          | Description                                                        | Example                         |
-| ----------------- | ------------------------------------------------------------------ | ------------------------------- |
-| `VISION_API_KEY`  | Vision API key                                                     | `sk-your-api-key`               |
-| `VISION_API_URL`  | Vision API base URL                                                | `https://your-api-endpoint/v1`  |
-| `VISION_MODEL`    | Vision model name<br>(not needed for MiniMax)                      | `your-vision-model`             |
-| `VISION_API_TYPE` | Optional, force API type<br>`openai` / `minimax`                   | `minimax`                       |
+| Variable                | Description                                                        | Example                         |
+| ----------------------- | ------------------------------------------------------------------ | ------------------------------- |
+| `VISION_MODE`           | Delegation mode: `api` (default) or `subagent`. Auto-detects if unset — uses `api` when `VISION_API_KEY` is set, otherwise falls back to `subagent`. | `subagent` |
+| `VISION_API_KEY`        | Vision API key (required for `api` mode)                           | `sk-your-api-key`               |
+| `VISION_API_URL`        | Vision API base URL (required for `api` mode)                      | `https://your-api-endpoint/v1`  |
+| `VISION_MODEL`          | Vision model name (required for OpenAI-compatible backends; not needed for MiniMax) | `your-vision-model`             |
+| `VISION_API_TYPE`       | Optional, force API type `openai` / `minimax`                      | `minimax`                       |
+| `VISION_SUBAGENT_NAME`  | Subagent identifier for `subagent` mode (default: `image-reader`)  | `image-reader`                  |
+| `VISION_MAX_TOKENS`     | Vision API max response tokens (default: 4096)                     | `4096`                          |
+| `VISION_FETCH_TIMEOUT_MS` | Fetch timeout in ms (default: 60000)                             | `60000`                         |
+| `VISION_MAX_IMAGES`     | LRU image cache cap (default: 200)                                 | `200`                           |
+
+### Delegation Modes
+
+The plugin supports two modes for obtaining image descriptions when the active model lacks vision:
+
+#### `api` mode (default, original behaviour)
+
+The `vision` tool calls an external VLM API directly. Requires `VISION_API_KEY` and `VISION_API_URL`. Supports OpenAI-compatible backends and MiniMax VLM.
+
+```bash
+export VISION_MODE=api
+export VISION_API_KEY="sk-your-api-key"
+export VISION_API_URL="https://your-api-endpoint/v1"
+export VISION_MODEL="your-vision-model"
+```
+
+#### `subagent` mode (new)
+
+The plugin instructs the LLM to delegate image analysis to a vision-capable subagent via the Task tool. No external API key required — the subagent runs on whatever multimodal model is configured in opencode (e.g. `opencode-go/minimax-m3`).
+
+```bash
+export VISION_MODE=subagent
+# Optional: override the subagent name (default: image-reader)
+# export VISION_SUBAGENT_NAME=image-reader
+```
+
+**Setup for subagent mode:**
+
+1. Create a subagent definition at `~/.config/opencode/agent/image-reader.md`:
+
+```markdown
+---
+description: Analyzes images and screenshots using a multimodal model. Use when the main agent cannot view images.
+mode: subagent
+model: opencode-go/minimax-m3
+permission:
+  read: allow
+  glob: allow
+  list: allow
+  bash: deny
+  edit: deny
+---
+
+You are a vision analyst. Read the image at the given path using the `read` tool and describe what you see.
+```
+
+2. Restart opencode. The plugin will automatically:
+   - Save pasted images to `/tmp/opencode-vision/image{N}/`
+   - Inject a system prompt instructing the non-vision model to delegate
+   - Inject a path hint naming the subagent
+
+#### Auto-fallback
+
+When `VISION_MODE` is unset, the plugin uses:
+- `api` mode if `VISION_API_KEY` is present
+- `subagent` mode otherwise
+
+This means the plugin works out-of-the-box without any external credentials, as long as a vision-capable subagent is configured.
 
 > `VISION_API_URL`: OpenAI-compatible backends auto-append `/chat/completions`; MiniMax auto-detects and uses `/v1/coding_plan/vlm`.
 >
diff --git a/plugins/vision-helper.ts b/plugins/vision-helper.ts
index 402091d..3447603 100644
--- a/plugins/vision-helper.ts
+++ b/plugins/vision-helper.ts
@@ -42,11 +42,38 @@ function isPluginInjectedText(text: string): boolean {
   if (!text) return false
   return (
     /^\[Image #\d+ auto-saved to /.test(text) ||
+    /^\[Image #\d+ \w+\.\w+ auto-saved to /.test(text) ||
     /^\[Images auto-saved to:/.test(text) ||
+    /^\[Images \(\d+\) auto-saved to:/.test(text) ||
     /^\[vision: image\d+\/[\w-]+\.[\w]+]$/.test(text)
   )
 }
 
+// ── Delegation mode ──
+//
+// VISION_MODE controls how non-vision models obtain image descriptions:
+//   "api"      (default, original) — the vision tool calls an external VLM
+//              API (VISION_API_KEY + VISION_API_URL). This is the upstream
+//              behaviour and is left untouched.
+//   "subagent" — the plugin instructs the LLM to delegate image analysis to
+//              the @image-reader subagent via the Task tool. No external API
+//              key is required; the subagent runs on whatever vision-capable
+//              model is configured in opencode (e.g. opencode-go/minimax-m3).
+//
+// Auto-fallback: when VISION_MODE is unset, the plugin uses "api" mode if
+// VISION_API_KEY is present, otherwise it falls back to "subagent" mode so
+// the plugin works out-of-the-box without any external credentials.
+//
+// VISION_SUBAGENT_NAME overrides the subagent identifier injected into the
+// system prompt and path hint (default: "image-reader").
+const VISION_MODE_RAW = (process.env["VISION_MODE"] || "").toLowerCase()
+const VISION_SUBAGENT_NAME = process.env["VISION_SUBAGENT_NAME"] || "image-reader"
+const hasApiKey = !!process.env["VISION_API_KEY"]
+const VISION_MODE: "api" | "subagent" =
+  VISION_MODE_RAW === "subagent" ? "subagent" :
+  VISION_MODE_RAW === "api" ? "api" :
+  hasApiKey ? "api" : "subagent"
+
 /**
  * Hook runs just before messages are sent to the model. For every user message
  * with attached images:
@@ -100,6 +127,9 @@ export default (async () => {
           "**Native-vision models should NEVER call this tool — use the built-in `read` tool instead, which returns the actual image attachment directly. This tool exists for text-only models that cannot parse image bytes returned by `read`.**",
         ].join("\n")
       }
+      // In subagent mode, the vision tool is typically absent (no VISION_API_KEY).
+      // OpenCode silently ignores tool.definition calls for tools that don't
+      // exist, so this hook is a no-op in that case — no extra guard needed.
     },
     "experimental.chat.system.transform": async (input, output) => {
       const model = input.model as unknown as {
@@ -112,6 +142,10 @@ export default (async () => {
         output.system.push(
           "You have native image input capabilities. You can directly view and analyze images attached to user messages. Do NOT call the `vision` tool to read images sent by the user — analyze them natively instead.",
         )
+      } else if (VISION_MODE === "subagent") {
+        output.system.push(
+          `IMPORTANT: This model does NOT support image input. When a user attaches an image or screenshot, OpenCode will save it to a temp directory and inject a path hint like '[Image #N auto-saved to /tmp/opencode-vision/imageN/hash.png]'. You MUST delegate image analysis to the @${VISION_SUBAGENT_NAME} subagent via the Task tool (subagent_type="${VISION_SUBAGENT_NAME}", prompt="Read and describe the image at <path>"). The @${VISION_SUBAGENT_NAME} subagent runs on a multimodal model (e.g. opencode-go/minimax-m3) that can read images. Never attempt to read images directly with the \`read\` tool — it will fail with 'model does not support image input'.`,
+        )
       }
     },
     "experimental.chat.messages.transform": async (_input, output) => {
@@ -177,15 +211,18 @@ export default (async () => {
 
         if (saved.length === 0) continue
 
-        // Build path hint(s). Intentionally does NOT guide the LLM to the
-        // vision tool — the tool.definition hook above steers native-vision
-        // models toward the built-in read tool, and the vision tool's own
-        // description recommends read for native-vision models. The hint
-        // just records where the temp copy is, so any model that needs it
-        // can find it.
+        // Build path hint(s). The hint records where the temp copy lives so
+        // any model that needs it can find it. In "api" mode the hint is
+        // neutral (the vision tool's own description handles routing); in
+        // "subagent" mode the hint explicitly names the @image-reader
+        // subagent so the LLM knows to delegate via the Task tool.
+        const hintSuffix = VISION_MODE === "subagent"
+          ? ` — use @${VISION_SUBAGENT_NAME} subagent via Task tool to analyze it if you cannot view images natively]`
+          : `]`
+
         const hints = saved.length === 1
-          ? `[Image #${saved[0].seq} auto-saved to ${path.join(TMP_DIR, `image${saved[0].seq}`, saved[0].name)}]`
-          : `[Images auto-saved to:\n${saved.map((s) => `  ${path.join(TMP_DIR, `image${s.seq}`, s.name)}`).join("\n")}]`
+          ? `[Image #${saved[0].seq} ${saved[0].name} auto-saved to ${path.join(TMP_DIR, `image${saved[0].seq}`, saved[0].name)}${hintSuffix}`
+          : `[Images (${saved.length}) auto-saved to:\n${saved.map((s) => `  ${path.join(TMP_DIR, `image${s.seq}`, s.name)}`).join("\n")}${hintSuffix}`
 
         msg.parts.push({
           type: "text",