fix: preserve tuple items in schema build and harden athena prompt path guard

script/build-schema-document.ts

@@ -25,8 +25,10 @@ function removeDefaultedFromRequired(schema: Record<string, unknown>): Record<st
     result.properties = newProps
   }
 
-  if (result.items && typeof result.items === "object") {
+  if (result.items && typeof result.items === "object" && !Array.isArray(result.items)) {
     result.items = removeDefaultedFromRequired(result.items as Record<string, unknown>)
+  } else if (Array.isArray(result.items)) {
+    result.items = result.items.map((item) => removeDefaultedFromRequired(item as Record<string, unknown>))
   }
 
   for (const key of ["allOf", "anyOf", "oneOf"]) {

src/tools/athena-council/tools.ts

@@ -1,6 +1,6 @@
 import { tool, type ToolDefinition } from "@opencode-ai/plugin"
 import { readFile } from "node:fs/promises"
-import { resolve } from "node:path"
+import { resolve, sep } from "node:path"
 import type { BackgroundManager } from "../../features/background-agent"
 import type { CouncilConfig, CouncilMemberConfig } from "../../config/schema/athena"
 import { launchCouncilMember, type CouncilLaunchContext } from "./council-launcher"
@@ -128,7 +128,7 @@ export function createAthenaCouncilTool(args: {
       let promptContent: string
       try {
         const resolvedPath = resolve(directory, toolArgs.prompt_file)
-        const expectedPrefix = resolve(directory, ".sisyphus/tmp")
+        const expectedPrefix = `${resolve(directory, ".sisyphus/tmp")}${sep}`
         if (!resolvedPath.startsWith(expectedPrefix)) {
           return `Invalid prompt_file path: expected path within .sisyphus/tmp/, got: ${toolArgs.prompt_file}`
         }