refactor(rules-engine): centralize rule constants and AGENTS.md walk-up

Promote the project-rule constants (PROJECT_MARKERS, PROJECT_RULE_SUBDIRS, PROJECT_RULE_FILES, OPENCODE_USER_RULE_DIRS, USER_RULE_DIR, GITHUB_INSTRUCTIONS_PATTERN, RULE_EXTENSIONS, AGENTS_FILENAME, etc.) and the findAgentsMdUp walk-up helper out of the agents-md-core and rules-injector adapters and into @oh-my-opencode/rules-engine, the single owner of rule discovery.

- packages/agents-md-core/ drops the findAgentsMdUp/AgentsMdDiscoveryInput wrappers (now sourced directly from rules-engine) and its constants module re-exports AGENTS_FILENAME from rules-engine instead of duplicating it.
- src/hooks/directory-agents-injector/finder.ts pulls findAgentsMdUp from rules-engine directly while still re-exporting resolveFilePath from agents-md-core.
- src/hooks/rules-injector/constants.ts becomes a pure re-export shim over the rules-engine constants.

Add packages/agents-md-core/src/injector.test.ts to lock the root-skipping AGENTS.md injection order so future changes to findAgentsMdUp cannot silently regress the [Directory Context: ...] block format the injector emits.

Tests: bun test packages/agents-md-core packages/rules-engine src/hooks/directory-agents-injector src/hooks/rules-injector

packages/agents-md-core/src/constants.ts

@@ -1,4 +1,4 @@
-export const AGENTS_FILENAME = "AGENTS.md";
+export { AGENTS_FILENAME } from "../../rules-engine/src/constants";
 
 export const TRUNCATION_NOTICE_PREFIX =
   "\n\n[Note: Content was truncated to save context window space. For full context, please read the file directly: ";

packages/agents-md-core/src/finder.ts

@@ -1,20 +1,7 @@
-import {
-  findAgentsMdUp as findAgentsMdUpCore,
-} from "@oh-my-opencode/rules-engine";
 import { isAbsolute, resolve } from "node:path";
 
-import type { AgentsMdDiscoveryInput } from "./types";
-
 export function resolveFilePath(rootDirectory: string, path: string): string | null {
   if (!path) return null;
   if (isAbsolute(path)) return path;
   return resolve(rootDirectory, path);
 }
-
-export async function findAgentsMdUp(input: AgentsMdDiscoveryInput): Promise<string[]> {
-  return findAgentsMdUpCore({
-    startDir: input.startDir,
-    rootDir: input.rootDir,
-    cache: input.cache,
-  });
-}

packages/agents-md-core/src/index.ts

@@ -1,11 +1,10 @@
 export { AGENTS_FILENAME } from "./constants";
-export { findAgentsMdUp, resolveFilePath } from "./finder";
+export { resolveFilePath } from "./finder";
 export { formatAgentsMdContextBlock } from "./formatter";
 export { getSessionCache } from "./injection-cache";
 export { processFilePathForAgentsInjection } from "./injector";
 export type {
   AgentsMdContextOutput,
-  AgentsMdDiscoveryInput,
   AgentsMdInjectedPathsStorage,
   AgentsMdTruncator,
   TruncationResult,

packages/agents-md-core/src/injector.test.ts

@@ -0,0 +1,82 @@
+import { randomUUID } from "node:crypto";
+import { mkdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "bun:test";
+
+import { processFilePathForAgentsInjection } from "./injector";
+
+describe("processFilePathForAgentsInjection", () => {
+  const sessionCaches = new Map<string, Set<string>>();
+  const storageBackfill = new Map<string, Set<string>>();
+  const storage = {
+    loadInjectedPaths: (sessionID: string): Set<string> =>
+      storageBackfill.get(sessionID) ?? new Set<string>(),
+    saveInjectedPaths: (sessionID: string, paths: Set<string>): void => {
+      storageBackfill.set(sessionID, paths);
+    },
+  };
+
+  const truncator = {
+    truncate: async (_sessionID: string, content: string) => ({
+      result: content,
+      truncated: false,
+    }),
+  };
+
+  let rootDirectory = "";
+
+  afterEach(() => {
+    if (rootDirectory) {
+      rmSync(rootDirectory, { recursive: true, force: true });
+    }
+    rootDirectory = "";
+    sessionCaches.clear();
+    storageBackfill.clear();
+  });
+
+  it("injects AGENTS.md chain in root-skipping order with unchanged context format", async () => {
+    // given
+    rootDirectory = join(tmpdir(), `agents-md-core-injector-${randomUUID()}`);
+    const srcDirectory = join(rootDirectory, "src");
+    const nestedDirectory = join(srcDirectory, "components");
+    mkdirSync(nestedDirectory, { recursive: true });
+
+    const rootAgents = "# root";
+    const srcAgents = "# src";
+    const nestedAgents = "# nested";
+
+    writeFileSync(join(rootDirectory, "AGENTS.md"), rootAgents);
+    writeFileSync(join(srcDirectory, "AGENTS.md"), srcAgents);
+    writeFileSync(join(nestedDirectory, "AGENTS.md"), nestedAgents);
+    writeFileSync(join(nestedDirectory, "button.ts"), "export const button = true;\n");
+
+    const output = {
+      title: "read result",
+      output: "base output",
+      metadata: {},
+    };
+
+    const srcAgentsPath = join(srcDirectory, "AGENTS.md");
+    const nestedAgentsPath = join(nestedDirectory, "AGENTS.md");
+    const expectedOutput =
+      "base output" +
+      `\n\n[Directory Context: ${srcAgentsPath}]\n${srcAgents}` +
+      `\n\n[Directory Context: ${nestedAgentsPath}]\n${nestedAgents}`;
+
+    // when
+    await processFilePathForAgentsInjection({
+      rootDirectory,
+      truncator,
+      sessionCaches,
+      storage,
+      filePath: join(nestedDirectory, "button.ts"),
+      sessionID: "session-regression",
+      output,
+    });
+
+    // then
+    expect(output.output).toBe(expectedOutput);
+    expect(output.output).not.toContain(rootAgents);
+  });
+});

packages/agents-md-core/src/injector.ts

@@ -1,8 +1,12 @@
-import type { AgentsMdCache } from "@oh-my-opencode/rules-engine";
+import {
+  findAgentsMdUp,
+  type AgentsMdCache,
+  type FindAgentsMdUpInput,
+} from "@oh-my-opencode/rules-engine";
 import { promises as fsPromises } from "node:fs";
 import { dirname } from "node:path";
 
-import { findAgentsMdUp, resolveFilePath } from "./finder";
+import { resolveFilePath } from "./finder";
 import { formatAgentsMdContextBlock } from "./formatter";
 import { getSessionCache } from "./injection-cache";
 import type {
@@ -33,11 +37,12 @@ export async function processFilePathForAgentsInjection(input: {
     storage: input.storage,
   });
 
-  const agentsPaths = await findAgentsMdUp({
+  const agentsMdDiscoveryInput: FindAgentsMdUpInput = {
     startDir: dir,
     rootDir: input.rootDirectory,
     cache: input.agentsMdCache,
-  });
+  };
+  const agentsPaths = await findAgentsMdUp(agentsMdDiscoveryInput);
 
   let dirty = false;
   for (const agentsPath of agentsPaths) {

packages/agents-md-core/src/types.ts

@@ -1,5 +1,3 @@
-import type { AgentsMdCache } from "@oh-my-opencode/rules-engine";
-
 export interface TruncationResult {
   readonly result: string;
   readonly truncated: boolean;
@@ -19,9 +17,3 @@ export interface AgentsMdInjectedPathsStorage {
   loadInjectedPaths(sessionID: string): Set<string>;
   saveInjectedPaths(sessionID: string, paths: Set<string>): void;
 }
-
-export interface AgentsMdDiscoveryInput {
-  readonly startDir: string;
-  readonly rootDir: string;
-  readonly cache?: AgentsMdCache;
-}

packages/rules-engine/src/index.ts

@@ -6,6 +6,19 @@ export { shouldApplyRule, createContentHash, isDuplicateByContentHash, isDuplica
 export { findProjectRoot, clearProjectRootCache } from "./project-root";
 export { calculateDistance } from "./distance";
 export { findRuleFilesRecursive, safeRealpathSync } from "./scanner";
+export {
+  AGENTS_FILENAME,
+  EXCLUDED_DIRS,
+  GITHUB_INSTRUCTIONS_PATTERN,
+  GLOBAL_DISTANCE,
+  OPENCODE_USER_RULE_DIRS,
+  PROJECT_MARKERS,
+  PROJECT_RULE_FILES,
+  PROJECT_RULE_SUBDIRS,
+  RULE_EXTENSIONS,
+  SOURCE_PRIORITY,
+  USER_RULE_DIR,
+} from "./constants";
 export type {
   AgentsMdCache,
   DirectoryScanEntry,

src/hooks/directory-agents-injector/finder.ts

@@ -1,4 +1,2 @@
-export {
-  findAgentsMdUp,
-  resolveFilePath,
-} from "@oh-my-opencode/agents-md-core";
+export { resolveFilePath } from "@oh-my-opencode/agents-md-core";
+export { findAgentsMdUp } from "@oh-my-opencode/rules-engine";

src/hooks/rules-injector/constants.ts

@@ -2,30 +2,12 @@ import { join } from "node:path";
 import { OPENCODE_STORAGE } from "../../shared";
 export const RULES_INJECTOR_STORAGE = join(OPENCODE_STORAGE, "rules-injector");
 
-export const PROJECT_MARKERS = [
-  ".git",
-  "pyproject.toml",
-  "package.json",
-  "Cargo.toml",
-  "go.mod",
-  ".venv",
-];
-
-export const PROJECT_RULE_SUBDIRS: [string, string][] = [
-  [".github", "instructions"],
-  [".cursor", "rules"],
-  [".claude", "rules"],
-  [".omo", "rules"],
-];
-
-export const PROJECT_RULE_FILES: string[] = [
-  ".github/copilot-instructions.md",
-];
-
-export const GITHUB_INSTRUCTIONS_PATTERN = /\.instructions\.md$/;
-
-export const USER_RULE_DIR = ".claude/rules";
-
-export const OPENCODE_USER_RULE_DIRS = [".omo/rules", ".opencode/rules"];
-
-export const RULE_EXTENSIONS = [".md", ".mdc"];
+export {
+  GITHUB_INSTRUCTIONS_PATTERN,
+  OPENCODE_USER_RULE_DIRS,
+  PROJECT_MARKERS,
+  PROJECT_RULE_FILES,
+  PROJECT_RULE_SUBDIRS,
+  RULE_EXTENSIONS,
+  USER_RULE_DIR,
+} from "@oh-my-opencode/rules-engine";