feat(pi): add subagent config and agents

modules/agents/pi/extensions/subagents/agents.ts

@@ -0,0 +1,141 @@
+import { existsSync, readdirSync, readFileSync } from "node:fs";
+import { homedir } from "node:os";
+import { basename, join } from "node:path";
+import type { ContextMode } from "./types.ts";
+import type { Diagnostics } from "./config.ts";
+
+export interface AgentDefinition {
+  name: string;
+  description: string;
+  body: string;
+  context?: ContextMode;
+  model?: string;
+  thinking?: string;
+  tools?: string;
+  allowedContexts?: ContextMode[];
+  hidden?: boolean;
+  source: string;
+}
+
+export function loadAgents(cwd: string, projectTrusted: boolean, diagnostics: Diagnostics, agentDir = defaultAgentDir()): Map<string, AgentDefinition> {
+  const user = loadTier(join(agentDir, "agents"), "user", diagnostics);
+  const project = projectTrusted ? loadTier(join(cwd, ".pi", "agents"), "project", diagnostics) : new Map<string, AgentDefinition>();
+  return new Map([...user, ...project]);
+}
+
+function loadTier(dir: string, tier: string, diagnostics: Diagnostics): Map<string, AgentDefinition> {
+  const agents = new Map<string, AgentDefinition>();
+  if (!existsSync(dir)) return agents;
+  for (const entry of readdirSync(dir, { withFileTypes: true })) {
+    if (!entry.isFile() || !entry.name.endsWith(".md")) continue;
+    const path = join(dir, entry.name);
+    const parsed = parseAgent(path, diagnostics);
+    if (!parsed) continue;
+    if (agents.has(parsed.name)) {
+      diagnostics.warnings.push(`Duplicate ${tier} agent '${parsed.name}' ignored at ${path}`);
+      continue;
+    }
+    const stem = basename(entry.name, ".md");
+    if (stem !== parsed.name) diagnostics.warnings.push(`${tier} agent file '${entry.name}' name '${parsed.name}' does not match filename`);
+    agents.set(parsed.name, parsed);
+  }
+  return agents;
+}
+
+export function parseAgent(path: string, diagnostics: Diagnostics): AgentDefinition | undefined {
+  try {
+    const text = readFileSync(path, "utf8");
+    const match = /^---\n([\s\S]*?)\n---\n?([\s\S]*)$/u.exec(text);
+    if (!match) {
+      diagnostics.warnings.push(`Agent ${path} missing YAML frontmatter`);
+      return undefined;
+    }
+    const frontmatter = parseFrontmatter(match[1]);
+    const name = stringField(frontmatter, "name");
+    const description = stringField(frontmatter, "description");
+    if (!name || !/^[a-z0-9-]+$/.test(name)) {
+      diagnostics.warnings.push(`Agent ${path} has invalid name`);
+      return undefined;
+    }
+    if (!description) {
+      diagnostics.warnings.push(`Agent ${path} has invalid description`);
+      return undefined;
+    }
+    const context = contextField(frontmatter.context);
+    const allowedContexts = contextsField(frontmatter.allowedContexts);
+    if (frontmatter.context !== undefined && !context) diagnostics.warnings.push(`Agent ${path} has invalid context`);
+    if (frontmatter.allowedContexts !== undefined && !allowedContexts) diagnostics.warnings.push(`Agent ${path} has invalid allowedContexts`);
+    if (context && allowedContexts && !allowedContexts.includes(context)) diagnostics.warnings.push(`Agent ${path} context is outside allowedContexts`);
+    return {
+      name,
+      description,
+      body: match[2].trim(),
+      context,
+      model: stringField(frontmatter, "model"),
+      thinking: stringField(frontmatter, "thinking"),
+      tools: stringField(frontmatter, "tools"),
+      allowedContexts,
+      hidden: booleanField(frontmatter, "hidden"),
+      source: path,
+    };
+  } catch (error) {
+    diagnostics.warnings.push(`Failed to load agent ${path}: ${error instanceof Error ? error.message : String(error)}`);
+    return undefined;
+  }
+}
+
+function parseFrontmatter(text: string): Record<string, unknown> {
+  const result: Record<string, unknown> = {};
+  const lines = text.split(/\r?\n/u);
+  for (let i = 0; i < lines.length; i += 1) {
+    const line = lines[i];
+    if (!line.trim() || line.trimStart().startsWith("#")) continue;
+    const scalar = /^(\w+):\s*(.*?)\s*$/u.exec(line);
+    if (!scalar) continue;
+    const [, key, raw] = scalar;
+    if (raw !== "") {
+      result[key] = parseScalar(raw);
+      continue;
+    }
+    const values: string[] = [];
+    while (i + 1 < lines.length) {
+      const item = /^\s+-\s*(.*?)\s*$/u.exec(lines[i + 1]);
+      if (!item) break;
+      values.push(String(parseScalar(item[1])));
+      i += 1;
+    }
+    result[key] = values;
+  }
+  return result;
+}
+
+function parseScalar(raw: string): string | boolean {
+  const unquoted = raw.replace(/^['"]|['"]$/gu, "");
+  if (unquoted === "true") return true;
+  if (unquoted === "false") return false;
+  return unquoted;
+}
+
+function stringField(record: Record<string, unknown>, key: string): string | undefined {
+  const value = record[key];
+  return typeof value === "string" && value.trim() ? value.trim() : undefined;
+}
+
+function booleanField(record: Record<string, unknown>, key: string): boolean | undefined {
+  const value = record[key];
+  return typeof value === "boolean" ? value : undefined;
+}
+
+function contextField(value: unknown): ContextMode | undefined {
+  return value === "independent" || value === "fork" ? value : undefined;
+}
+
+function contextsField(value: unknown): ContextMode[] | undefined {
+  if (!Array.isArray(value)) return undefined;
+  const contexts = value.map(contextField);
+  return contexts.every(Boolean) ? (contexts as ContextMode[]) : undefined;
+}
+
+function defaultAgentDir(): string {
+  return process.env.PI_CODING_AGENT_DIR ?? join(homedir(), ".pi", "agent");
+}