diff --git a/packages/core/src/flag/flag.ts b/packages/core/src/flag/flag.ts
index dcb7a1528f..c7be32dd7f 100644
--- a/packages/core/src/flag/flag.ts
+++ b/packages/core/src/flag/flag.ts
@@ -29,7 +29,6 @@ export const Flag = {
   OPENCODE_DISABLE_MODELS_FETCH: truthy("OPENCODE_DISABLE_MODELS_FETCH"),
   OPENCODE_DISABLE_MOUSE: truthy("OPENCODE_DISABLE_MOUSE"),
   OPENCODE_DISABLE_CLAUDE_CODE,
-  OPENCODE_DISABLE_CLAUDE_CODE_PROMPT: OPENCODE_DISABLE_CLAUDE_CODE || truthy("OPENCODE_DISABLE_CLAUDE_CODE_PROMPT"),
   OPENCODE_FAKE_VCS: process.env["OPENCODE_FAKE_VCS"],
   OPENCODE_SERVER_PASSWORD: process.env["OPENCODE_SERVER_PASSWORD"],
   OPENCODE_SERVER_USERNAME: process.env["OPENCODE_SERVER_USERNAME"],
diff --git a/packages/opencode/src/effect/runtime-flags.ts b/packages/opencode/src/effect/runtime-flags.ts
index 50dd6d2f9a..27ea848958 100644
--- a/packages/opencode/src/effect/runtime-flags.ts
+++ b/packages/opencode/src/effect/runtime-flags.ts
@@ -18,6 +18,10 @@ export class Service extends ConfigService.Service<Service>()("@opencode/Runtime
   disableChannelDb: bool("OPENCODE_DISABLE_CHANNEL_DB"),
   disableEmbeddedWebUi: bool("OPENCODE_DISABLE_EMBEDDED_WEB_UI"),
   disableExternalSkills: bool("OPENCODE_DISABLE_EXTERNAL_SKILLS"),
+  disableClaudeCodePrompt: Config.all({
+    broad: bool("OPENCODE_DISABLE_CLAUDE_CODE"),
+    direct: bool("OPENCODE_DISABLE_CLAUDE_CODE_PROMPT"),
+  }).pipe(Config.map((flags) => flags.broad || flags.direct)),
   disableClaudeCodeSkills: Config.all({
     broad: bool("OPENCODE_DISABLE_CLAUDE_CODE"),
     direct: bool("OPENCODE_DISABLE_CLAUDE_CODE_SKILLS"),
diff --git a/packages/opencode/src/session/instruction.ts b/packages/opencode/src/session/instruction.ts
index 63f0c36367..ad9a74445b 100644
--- a/packages/opencode/src/session/instruction.ts
+++ b/packages/opencode/src/session/instruction.ts
@@ -3,6 +3,7 @@ import { Effect, Layer, Context } from "effect"
 import { FetchHttpClient, HttpClient, HttpClientRequest } from "effect/unstable/http"
 import { Config } from "@/config/config"
 import { InstanceState } from "@/effect/instance-state"
+import { RuntimeFlags } from "@/effect/runtime-flags"
 import { Flag } from "@opencode-ai/core/flag/flag"
 import { AppFileSystem } from "@opencode-ai/core/filesystem"
 import { withTransientReadRetry } from "@/util/effect-http-client"
@@ -10,9 +11,9 @@ import { Global } from "@opencode-ai/core/global"
 import type { MessageV2 } from "./message-v2"
 import type { MessageID } from "./schema"
 
-const FILES = [
+const files = (disableClaudeCodePrompt: boolean) => [
   "AGENTS.md",
-  ...(Flag.OPENCODE_DISABLE_CLAUDE_CODE_PROMPT ? [] : ["CLAUDE.md"]),
+  ...(disableClaudeCodePrompt ? [] : ["CLAUDE.md"]),
   "CONTEXT.md", // deprecated
 ]
 
@@ -50,18 +51,20 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/In
 export const layer: Layer.Layer<
   Service,
   never,
-  AppFileSystem.Service | Config.Service | Global.Service | HttpClient.HttpClient
+  AppFileSystem.Service | Config.Service | Global.Service | HttpClient.HttpClient | RuntimeFlags.Service
 > = Layer.effect(
   Service,
   Effect.gen(function* () {
     const cfg = yield* Config.Service
     const fs = yield* AppFileSystem.Service
     const global = yield* Global.Service
+    const flags = yield* RuntimeFlags.Service
     const http = HttpClient.filterStatusOk(withTransientReadRetry(yield* HttpClient.HttpClient))
     const globalFiles = [
       path.join(global.config, "AGENTS.md"),
-      ...(!Flag.OPENCODE_DISABLE_CLAUDE_CODE_PROMPT ? [path.join(global.home, ".claude", "CLAUDE.md")] : []),
+      ...(!flags.disableClaudeCodePrompt ? [path.join(global.home, ".claude", "CLAUDE.md")] : []),
     ]
+    const instructionFiles = files(flags.disableClaudeCodePrompt)
 
     const state = yield* InstanceState.make(
       Effect.fn("Instruction.state")(() =>
@@ -117,7 +120,7 @@ export const layer: Layer.Layer<
 
       // The first project-level match wins so we don't stack AGENTS.md/CLAUDE.md from every ancestor.
       if (!Flag.OPENCODE_DISABLE_PROJECT_CONFIG) {
-        for (const file of FILES) {
+        for (const file of instructionFiles) {
           const matches = yield* fs
             .findUp(file, ctx.directory, ctx.worktree)
             .pipe(Effect.catch(() => Effect.succeed([])))
@@ -165,7 +168,7 @@ export const layer: Layer.Layer<
     })
 
     const find = Effect.fn("Instruction.find")(function* (dir: string) {
-      for (const file of FILES) {
+      for (const file of instructionFiles) {
         const filepath = path.resolve(path.join(dir, file))
         if (yield* fs.existsSafe(filepath)) return filepath
       }
@@ -225,6 +228,7 @@ export const defaultLayer = layer.pipe(
   Layer.provide(Global.layer),
   Layer.provide(AppFileSystem.defaultLayer),
   Layer.provide(FetchHttpClient.layer),
+  Layer.provide(RuntimeFlags.defaultLayer),
 )
 
 export function loaded(messages: MessageV2.WithParts[]) {
diff --git a/packages/opencode/test/effect/runtime-flags.test.ts b/packages/opencode/test/effect/runtime-flags.test.ts
index 8d265cdaca..41d158652f 100644
--- a/packages/opencode/test/effect/runtime-flags.test.ts
+++ b/packages/opencode/test/effect/runtime-flags.test.ts
@@ -44,6 +44,7 @@ describe("RuntimeFlags", () => {
       expect(flags.disableChannelDb).toBe(true)
       expect(flags.disableEmbeddedWebUi).toBe(true)
       expect(flags.disableExternalSkills).toBe(true)
+      expect(flags.disableClaudeCodePrompt).toBe(false)
       expect(flags.enableExa).toBe(true)
       expect(flags.enableParallel).toBe(true)
       expect(flags.enableExperimentalModels).toBe(true)
@@ -87,6 +88,7 @@ describe("RuntimeFlags", () => {
       expect(flags.disableChannelDb).toBe(false)
       expect(flags.disableEmbeddedWebUi).toBe(false)
       expect(flags.disableExternalSkills).toBe(false)
+      expect(flags.disableClaudeCodePrompt).toBe(false)
       expect(flags.disableClaudeCodeSkills).toBe(false)
       expect(flags.enableExa).toBe(false)
       expect(flags.experimentalIconDiscovery).toBe(false)
@@ -122,6 +124,30 @@ describe("RuntimeFlags", () => {
     }),
   )
 
+  it.effect("disableClaudeCodePrompt defaults to false", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(Effect.provide(fromConfig({})))
+
+      expect(flags.disableClaudeCodePrompt).toBe(false)
+    }),
+  )
+
+  it.effect("disableClaudeCodePrompt reads OPENCODE_DISABLE_CLAUDE_CODE_PROMPT", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(Effect.provide(fromConfig({ OPENCODE_DISABLE_CLAUDE_CODE_PROMPT: "true" })))
+
+      expect(flags.disableClaudeCodePrompt).toBe(true)
+    }),
+  )
+
+  it.effect("disableClaudeCodePrompt inherits OPENCODE_DISABLE_CLAUDE_CODE", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(Effect.provide(fromConfig({ OPENCODE_DISABLE_CLAUDE_CODE: "true" })))
+
+      expect(flags.disableClaudeCodePrompt).toBe(true)
+    }),
+  )
+
   it.effect("experimentalIconDiscovery reads OPENCODE_EXPERIMENTAL_ICON_DISCOVERY", () =>
     Effect.gen(function* () {
       const flags = yield* readFlags.pipe(Effect.provide(fromConfig({ OPENCODE_EXPERIMENTAL_ICON_DISCOVERY: "true" })))
@@ -256,6 +282,7 @@ describe("RuntimeFlags", () => {
       expect(flags.disableChannelDb).toBe(false)
       expect(flags.disableEmbeddedWebUi).toBe(false)
       expect(flags.disableExternalSkills).toBe(false)
+      expect(flags.disableClaudeCodePrompt).toBe(false)
       expect(flags.disableClaudeCodeSkills).toBe(false)
       expect(flags.enableExa).toBe(false)
       expect(flags.experimentalIconDiscovery).toBe(false)
diff --git a/packages/opencode/test/session/instruction.test.ts b/packages/opencode/test/session/instruction.test.ts
index 5d40933954..0f9c340dd4 100644
--- a/packages/opencode/test/session/instruction.test.ts
+++ b/packages/opencode/test/session/instruction.test.ts
@@ -10,6 +10,7 @@ import { Instruction } from "../../src/session/instruction"
 import type { MessageV2 } from "../../src/session/message-v2"
 import { MessageID, PartID, SessionID } from "../../src/session/schema"
 import { Global } from "@opencode-ai/core/global"
+import { RuntimeFlags } from "../../src/effect/runtime-flags"
 import { provideInstance, provideTmpdirInstance, tmpdirScoped } from "../fixture/fixture"
 import { testEffect } from "../lib/effect"
 import { TestConfig } from "../fixture/config"
@@ -18,18 +19,19 @@ const it = testEffect(Layer.mergeAll(CrossSpawnSpawner.defaultLayer, NodeFileSys
 
 const configLayer = TestConfig.layer()
 
-const instructionLayer = (global: Partial<Global.Interface>) =>
+const instructionLayer = (global: Partial<Global.Interface>, flags: Partial<RuntimeFlags.Info> = {}) =>
   Instruction.layer.pipe(
     Layer.provide(configLayer),
     Layer.provide(AppFileSystem.defaultLayer),
     Layer.provide(FetchHttpClient.layer),
     Layer.provide(Global.layerWith(global)),
+    Layer.provide(RuntimeFlags.layer(flags)),
   )
 
 const provideInstruction =
-  (global: Partial<Global.Interface>) =>
+  (global: Partial<Global.Interface>, flags?: Partial<RuntimeFlags.Info>) =>
   <A, E, R>(self: Effect.Effect<A, E, R>) =>
-    self.pipe(Effect.provide(instructionLayer(global)))
+    self.pipe(Effect.provide(instructionLayer(global, flags)))
 
 const write = (filepath: string, content: string) =>
   Effect.gen(function* () {
@@ -215,6 +217,24 @@ describe("Instruction.system", () => {
       }).pipe(provideInstance(projectTmp), provideInstruction({ home: globalTmp, config: globalTmp }))
     }),
   )
+
+  it.live("skips project and global CLAUDE.md when Claude Code prompt is disabled", () =>
+    Effect.gen(function* () {
+      const globalTmp = yield* tmpWithFiles({ ".claude/CLAUDE.md": "# Global Claude" })
+      const projectTmp = yield* tmpWithFiles({ "CLAUDE.md": "# Project Claude" })
+
+      yield* Effect.gen(function* () {
+        const svc = yield* Instruction.Service
+        const paths = yield* svc.systemPaths()
+        expect(paths.has(path.join(globalTmp, ".claude", "CLAUDE.md"))).toBe(false)
+        expect(paths.has(path.join(projectTmp, "CLAUDE.md"))).toBe(false)
+        expect(yield* svc.system()).toEqual([])
+      }).pipe(
+        provideInstance(projectTmp),
+        provideInstruction({ home: globalTmp, config: globalTmp }, { disableClaudeCodePrompt: true }),
+      )
+    }),
+  )
 })
 
 describe("Instruction.systemPaths global config", () => {