fix(opencode): avoid nullable webfetch format schema (#30215)

packages/opencode/src/tool/webfetch.ts

@@ -17,7 +17,7 @@ export const Parameters = Schema.Struct({
       description: "The format to return the content in (text, markdown, or html). Defaults to markdown.",
       default: "markdown",
     })
-    .pipe(Schema.optional, Schema.withDecodingDefault(Effect.succeed("markdown" as const))),
+    .pipe(Schema.withDecodingDefault(Effect.succeed("markdown" as const))),
   timeout: Schema.optional(Schema.Number).annotate({ description: "Optional timeout in seconds (max 120)" }),
 })
 

packages/opencode/test/tool/__snapshots__/parameters.test.ts.snap

@@ -396,21 +396,14 @@ exports[`tool parameters JSON Schema (wire shape) webfetch 1`] = `
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "properties": {
     "format": {
-      "anyOf": [
+      "default": "markdown",
-        {
+      "description": "The format to return the content in (text, markdown, or html). Defaults to markdown.",
-          "default": "markdown",
+      "enum": [
-          "description": "The format to return the content in (text, markdown, or html). Defaults to markdown.",
+        "text",
-          "enum": [
+        "markdown",
-            "text",
+        "html",
-            "markdown",
-            "html",
-          ],
-          "type": "string",
-        },
-        {
-          "type": "null",
-        },
       ],
+      "type": "string",
     },
     "timeout": {
       "description": "Optional timeout in seconds (max 120)",

packages/opencode/test/tool/parameters.test.ts

@@ -82,6 +82,13 @@ describe("tool parameters", () => {
         properties: { value: { minimum: Number.MIN_SAFE_INTEGER, maximum: Number.MAX_SAFE_INTEGER } },
       })
     })
+
+    test("does not expose defaulted optional keys as nullable", () => {
+      expect(toJsonSchema(WebFetch)).toMatchObject({
+        properties: { format: { type: "string", enum: ["text", "markdown", "html"], default: "markdown" } },
+      })
+      expect(toJsonSchema(WebFetch).properties?.format).not.toHaveProperty("anyOf")
+    })
   })
 
   describe("apply_patch", () => {
@@ -257,8 +264,15 @@ describe("tool parameters", () => {
   })
 
   describe("webfetch", () => {
-    test("accepts url-only", () => {
+    test("defaults omitted format to markdown", () => {
-      expect(parse(WebFetch, { url: "https://example.com" }).url).toBe("https://example.com")
+      expect(parse(WebFetch, { url: "https://example.com" })).toEqual({
+        url: "https://example.com",
+        format: "markdown",
+      })
+      expect(parse(WebFetch, { url: "https://example.com", format: undefined })).toEqual({
+        url: "https://example.com",
+        format: "markdown",
+      })
     })
   })