diff --git a/packages/core/src/config.ts b/packages/core/src/config.ts
index e6cd3c5a16..f289a68e2f 100644
--- a/packages/core/src/config.ts
+++ b/packages/core/src/config.ts
@@ -139,7 +139,7 @@ export const layer = Layer.effect(
     const global = yield* Global.Service
     const location = yield* Location.Service
     const policy = yield* Policy.Service
-    const names = ["config.json", "opencode.json", "opencode.jsonc"]
+    const names = ["opencode.json", "opencode.jsonc"]
     const decodeOptions = { errors: "all", onExcessProperty: "ignore", propertyOrder: "original" } as const
     const decodeInfo = Schema.decodeUnknownOption(Info, decodeOptions)
     const decodeV1Info = Schema.decodeUnknownOption(ConfigV1.Info, decodeOptions)
diff --git a/packages/core/test/config/config.test.ts b/packages/core/test/config/config.test.ts
index a9e5cfc3d7..c3c42cab30 100644
--- a/packages/core/test/config/config.test.ts
+++ b/packages/core/test/config/config.test.ts
@@ -161,7 +161,7 @@ describe("Config", () => {
     ),
   )
 
-  it.live("loads JSON and JSONC files from lowest to highest priority", () =>
+  it.live("loads opencode JSON and JSONC files from lowest to highest priority", () =>
     Effect.acquireRelease(
       Effect.promise(() => tmpdir()),
       (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
@@ -170,13 +170,9 @@ describe("Config", () => {
         Effect.gen(function* () {
           yield* Effect.promise(() =>
             Promise.all([
-              fs.writeFile(
-                path.join(tmp.path, "config.json"),
-                JSON.stringify({ $schema: "base", providers: { base: provider } }),
-              ),
               fs.writeFile(
                 path.join(tmp.path, "opencode.json"),
-                JSON.stringify({ $schema: "middle", providers: { middle: provider } }),
+                JSON.stringify({ $schema: "base", providers: { base: provider } }),
               ),
               fs.writeFile(
                 path.join(tmp.path, "opencode.jsonc"),
@@ -192,12 +188,12 @@ describe("Config", () => {
             const config = yield* Config.Service
             const documents = (yield* config.entries()).filter((entry) => entry.type === "document")
 
-            expect(documents).toHaveLength(3)
-            expect(documents.map((document) => document.type)).toEqual(["document", "document", "document"])
-            expect(documents.map((document) => document.info.$schema)).toEqual(["base", "middle", "last"])
+            expect(documents).toHaveLength(2)
+            expect(documents.map((document) => document.type)).toEqual(["document", "document"])
+            expect(documents.map((document) => document.info.$schema)).toEqual(["base", "last"])
             expect(documents[0]).toBeInstanceOf(Config.Document)
-            expect(documents[0]?.path).toBe(path.join(tmp.path, "config.json"))
-            expect(documents[2]?.info.providers?.last).toBeInstanceOf(ConfigProvider.Info)
+            expect(documents[0]?.path).toBe(path.join(tmp.path, "opencode.json"))
+            expect(documents[1]?.info.providers?.last).toBeInstanceOf(ConfigProvider.Info)
 
             yield* Effect.promise(() =>
               fs.writeFile(path.join(tmp.path, "opencode.jsonc"), JSON.stringify({ $schema: "changed" })),
@@ -206,7 +202,29 @@ describe("Config", () => {
               (yield* config.entries())
                 .filter((entry) => entry.type === "document")
                 .map((document) => document.info.$schema),
-            ).toEqual(["base", "middle", "last"])
+            ).toEqual(["base", "last"])
+          }).pipe(Effect.provide(testLayer(tmp.path)))
+        }),
+      ),
+    ),
+  )
+
+  it.live("does not load legacy config.json files", () =>
+    Effect.acquireRelease(
+      Effect.promise(() => tmpdir()),
+      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
+    ).pipe(
+      Effect.flatMap((tmp) =>
+        Effect.gen(function* () {
+          yield* Effect.promise(() =>
+            fs.writeFile(path.join(tmp.path, "config.json"), JSON.stringify({ $schema: "legacy" })),
+          )
+
+          return yield* Effect.gen(function* () {
+            const config = yield* Config.Service
+            const documents = (yield* config.entries()).filter((entry) => entry.type === "document")
+
+            expect(documents).toHaveLength(0)
           }).pipe(Effect.provide(testLayer(tmp.path)))
         }),
       ),
@@ -648,7 +666,7 @@ describe("Config", () => {
     ),
   )
 
-  it.live("ignores invalid files while loading valid config values", () =>
+  it.live("ignores an invalid file while loading valid config values", () =>
     Effect.acquireRelease(
       Effect.promise(() => tmpdir()),
       (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
@@ -657,9 +675,8 @@ describe("Config", () => {
         Effect.gen(function* () {
           yield* Effect.promise(() =>
             Promise.all([
-              fs.writeFile(path.join(tmp.path, "config.json"), JSON.stringify({ $schema: "base" })),
-              fs.writeFile(path.join(tmp.path, "opencode.json"), "{ invalid"),
-              fs.writeFile(path.join(tmp.path, "opencode.jsonc"), JSON.stringify({ providers: { invalid: true } })),
+              fs.writeFile(path.join(tmp.path, "opencode.json"), JSON.stringify({ $schema: "base" })),
+              fs.writeFile(path.join(tmp.path, "opencode.jsonc"), "{ invalid"),
             ]),
           )
           return yield* Effect.gen(function* () {
@@ -728,7 +745,7 @@ describe("Config", () => {
               fs.writeFile(path.join(global, "opencode.json"), JSON.stringify({ $schema: "global" })),
               fs.writeFile(path.join(root, "opencode.json"), JSON.stringify({ $schema: "root" })),
               fs.writeFile(path.join(parent, "opencode.jsonc"), JSON.stringify({ $schema: "parent" })),
-              fs.writeFile(path.join(directory, "config.json"), JSON.stringify({ $schema: "directory" })),
+              fs.writeFile(path.join(directory, "opencode.json"), JSON.stringify({ $schema: "directory" })),
               fs.writeFile(path.join(root, ".opencode", "opencode.json"), JSON.stringify({ $schema: "root-dot" })),
               fs.writeFile(
                 path.join(directory, ".opencode", "opencode.jsonc"),
diff --git a/packages/core/test/config/plugin.test.ts b/packages/core/test/config/plugin.test.ts
index e6944368c4..2e134c55e1 100644
--- a/packages/core/test/config/plugin.test.ts
+++ b/packages/core/test/config/plugin.test.ts
@@ -25,7 +25,7 @@ describe("ConfigExternalPlugin", () => {
       const location = yield* Location.Service
       const npm = yield* Npm.Service
       const host = yield* PluginHost.make(plugins)
-      const document = path.join(import.meta.dir, "config.json")
+      const document = path.join(import.meta.dir, "opencode.json")
 
       yield* ConfigExternalPlugin.Plugin.effect(host).pipe(
         Effect.provideService(PluginV2.Service, plugins),
@@ -82,7 +82,7 @@ describe("ConfigExternalPlugin", () => {
               Effect.succeed([
                 new Config.Document({
                   type: "document",
-                  path: path.join(import.meta.dir, "config.json"),
+                  path: path.join(import.meta.dir, "opencode.json"),
                   info: decode({
                     plugins: [
                       {
@@ -125,7 +125,7 @@ describe("ConfigExternalPlugin", () => {
               Effect.succeed([
                 new Config.Document({
                   type: "document",
-                  path: path.join(import.meta.dir, "config.json"),
+                  path: path.join(import.meta.dir, "opencode.json"),
                   info: decode({
                     plugins: [
                       "../plugin/fixtures/missing-plugin.ts",
diff --git a/specs/v2/config.md b/specs/v2/config.md
index 9254af2094..96b0f3ac90 100644
--- a/specs/v2/config.md
+++ b/specs/v2/config.md
@@ -13,6 +13,8 @@ This document breaks the legacy configuration schema into small review groups. W
 
 Use one v2 config schema for now. Some fields, such as `autoupdate`, are intended for global/user configuration, but there is not yet enough benefit to enforce that with separate global and location schemas. Revisit this if more scope-sensitive fields survive the review.
 
+V2 core discovers config documents named `opencode.json` or `opencode.jsonc` in the global config directory, ancestor project directories, and `.opencode` config directories. The legacy `config.json` filename is not supported in V2.
+
 ## Group 1: File Metadata
 
 Small fields describing the config file itself rather than application behavior.