fix(core): filter unsupported media inputs (#38145)

Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>

packages/core/test/session-model-request.test.ts

@@ -0,0 +1,64 @@
+import { describe, expect, test } from "bun:test"
+import { Message, ToolResultPart } from "@opencode-ai/ai"
+import { unsupportedParts } from "@opencode-ai/core/session/model-request"
+
+const capabilities = (input: string[]) => ({ tools: true, input, output: ["text"] })
+
+describe("SessionModelRequest.unsupportedParts", () => {
+  test("replaces unsupported user media with a visible error", () => {
+    const messages = unsupportedParts(
+      [
+        Message.user([
+          Message.text("Describe this image"),
+          { type: "media", mediaType: "image/png", data: "aGVsbG8=", filename: "logo.png" },
+        ]),
+      ],
+      capabilities(["text"]),
+    )
+
+    expect(messages[0]?.content).toEqual([
+      Message.text("Describe this image"),
+      Message.text('ERROR: Cannot read "logo.png" (this model does not support image input). Inform the user.'),
+    ])
+  })
+
+  test("replaces unsupported media nested in tool results", () => {
+    const messages = unsupportedParts(
+      [
+        Message.tool(
+          ToolResultPart.make({
+            id: "call_1",
+            name: "read",
+            result: {
+              type: "content",
+              value: [
+                { type: "text", text: "Image read successfully" },
+                { type: "file", uri: "data:image/png;base64,aGVsbG8=", mime: "image/png", name: "logo.png" },
+              ],
+            },
+          }),
+        ),
+      ],
+      capabilities(["text"]),
+    )
+
+    expect(messages[0]?.content[0]).toMatchObject({
+      type: "tool-result",
+      result: {
+        type: "content",
+        value: [
+          { type: "text", text: "Image read successfully" },
+          {
+            type: "text",
+            text: 'ERROR: Cannot read "logo.png" (this model does not support image input). Inform the user.',
+          },
+        ],
+      },
+    })
+  })
+
+  test("preserves supported media", () => {
+    const message = Message.user({ type: "media", mediaType: "image/png", data: "aGVsbG8=" })
+    expect(unsupportedParts([message], capabilities(["text", "image"]))[0]?.content).toEqual(message.content)
+  })
+})