feat(environment): introduce disable_omo_env configuration option

- Added a new configuration option `disable_omo_env` to control the injection of the `<omo-env>` block in agent prompts.
- Updated relevant functions and tests to support this feature, ensuring that the environment context can be toggled on or off as needed.
- Enhanced documentation to reflect the new option and its implications for API cost and cache hit rates.

src/plugin-handlers/agent-config-handler.ts

@@ -76,6 +76,7 @@ export async function applyAgentConfig(params: {
   const currentModel = params.config.model as string | undefined;
   const disabledSkills = new Set<string>(params.pluginConfig.disabled_skills ?? []);
   const useTaskSystem = params.pluginConfig.experimental?.task_system ?? false;
+  const disableOmoEnv = params.pluginConfig.experimental?.disable_omo_env ?? false;
 
   const builtinAgents = await createBuiltinAgents(
     migratedDisabledAgents,
@@ -90,6 +91,7 @@ export async function applyAgentConfig(params: {
     currentModel,
     disabledSkills,
     useTaskSystem,
+    disableOmoEnv,
   );
 
   const includeClaudeAgents = params.pluginConfig.claude_code?.agents ?? true;

src/plugin-handlers/config-handler.test.ts

@@ -1275,3 +1275,65 @@ describe("per-agent todowrite/todoread deny when task_system enabled", () => {
     expect(agentResult[getAgentDisplayName("sisyphus")]?.permission?.todoread).toBeUndefined()
   })
 })
+
+describe("disable_omo_env pass-through", () => {
+  test("passes disable_omo_env=true to createBuiltinAgents", async () => {
+    //#given
+    const pluginConfig: OhMyOpenCodeConfig = {
+      experimental: { disable_omo_env: true },
+    }
+    const config: Record<string, unknown> = {
+      model: "anthropic/claude-opus-4-6",
+      agent: {},
+    }
+    const handler = createConfigHandler({
+      ctx: { directory: "/tmp" },
+      pluginConfig,
+      modelCacheState: {
+        anthropicContext1MEnabled: false,
+        modelContextLimitsCache: new Map(),
+      },
+    })
+
+    //#when
+    await handler(config)
+
+    //#then
+    const createBuiltinAgentsMock = agents.createBuiltinAgents as unknown as {
+      mock: { calls: unknown[][] }
+    }
+    const callArgs =
+      createBuiltinAgentsMock.mock.calls[createBuiltinAgentsMock.mock.calls.length - 1]
+    expect(callArgs).toBeDefined()
+    expect(callArgs?.[12]).toBe(true)
+  })
+
+  test("passes disable_omo_env=false when config field is omitted", async () => {
+    //#given
+    const pluginConfig: OhMyOpenCodeConfig = {}
+    const config: Record<string, unknown> = {
+      model: "anthropic/claude-opus-4-6",
+      agent: {},
+    }
+    const handler = createConfigHandler({
+      ctx: { directory: "/tmp" },
+      pluginConfig,
+      modelCacheState: {
+        anthropicContext1MEnabled: false,
+        modelContextLimitsCache: new Map(),
+      },
+    })
+
+    //#when
+    await handler(config)
+
+    //#then
+    const createBuiltinAgentsMock = agents.createBuiltinAgents as unknown as {
+      mock: { calls: unknown[][] }
+    }
+    const callArgs =
+      createBuiltinAgentsMock.mock.calls[createBuiltinAgentsMock.mock.calls.length - 1]
+    expect(callArgs).toBeDefined()
+    expect(callArgs?.[12]).toBe(false)
+  })
+})