feat(opencode): load repo root AGENTS for external reads

packages/opencode/src/session/instruction.ts

@@ -7,6 +7,7 @@ import { Instance } from "../project/instance"
 import { Flag } from "@/flag/flag"
 import { Log } from "../util/log"
 import { Glob } from "../util/glob"
+import { git } from "../util/git"
 import type { MessageV2 } from "./message-v2"
 
 const log = Log.create({ service: "instruction" })
@@ -42,6 +43,28 @@ async function resolveRelative(instruction: string): Promise<string[]> {
   return Filesystem.globUp(instruction, Flag.OPENCODE_CONFIG_DIR, Flag.OPENCODE_CONFIG_DIR).catch(() => [])
 }
 
+function normalize(cwd: string, value: string) {
+  const text = value.replace(/[\r\n]+$/, "")
+  if (!text) return
+  const resolved = Filesystem.windowsPath(text)
+  if (path.isAbsolute(resolved)) return path.normalize(resolved)
+  return path.resolve(cwd, resolved)
+}
+
+async function repo(filepath: string) {
+  const cwd = path.dirname(filepath)
+  const result = await git(["rev-parse", "--show-toplevel"], { cwd })
+  if (result.exitCode !== 0) return
+  return normalize(cwd, result.text())
+}
+
+async function main(filepath: string) {
+  const dir = await repo(filepath)
+  if (!dir) return
+  const file = path.resolve(path.join(dir, "AGENTS.md"))
+  if (await Filesystem.exists(file)) return file
+}
+
 export namespace InstructionPrompt {
   const state = Instance.state(() => {
     return {
@@ -187,6 +210,22 @@ export namespace InstructionPrompt {
       current = path.dirname(current)
     }
 
+    if (Instance.containsPath(target)) {
+      return results
+    }
+
+    const found = await main(target)
+    if (!found || found === target || system.has(found) || already.has(found) || isClaimed(messageID, found)) {
+      return results
+    }
+
+    claim(messageID, found)
+    const content = await Filesystem.readText(found).catch(() => undefined)
+    if (!content) {
+      return results
+    }
+
+    results.push({ filepath: found, content: "Instructions from: " + found + "\n" + content })
     return results
   }
 }

packages/opencode/test/session/instruction.test.ts

@@ -1,4 +1,5 @@
 import { afterEach, beforeEach, describe, expect, test } from "bun:test"
+import { $ } from "bun"
 import path from "path"
 import { InstructionPrompt } from "../../src/session/instruction"
 import { Instance } from "../../src/project/instance"
@@ -68,6 +69,34 @@ describe("InstructionPrompt.resolve", () => {
       },
     })
   })
+
+  test("returns repo root AGENTS.md for files outside current project", async () => {
+    await using external = await tmpdir({
+      init: async (dir) => {
+        await Bun.write(path.join(dir, "AGENTS.md"), "# External Root")
+        await Bun.write(path.join(dir, "subdir", "AGENTS.md"), "# External Subdir")
+        await Bun.write(path.join(dir, "subdir", "nested", "file.ts"), "const x = 1")
+      },
+    })
+    await using tmp = await tmpdir()
+
+    await $`git init`.cwd(external.path).quiet()
+    await $`git init`.cwd(tmp.path).quiet()
+
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const results = await InstructionPrompt.resolve(
+          [],
+          path.join(external.path, "subdir", "nested", "file.ts"),
+          "test-message-3",
+        )
+
+        expect(results.length).toBe(1)
+        expect(results[0].filepath).toBe(path.join(external.path, "AGENTS.md"))
+      },
+    })
+  })
 })
 
 describe("InstructionPrompt.systemPaths OPENCODE_CONFIG_DIR", () => {