refactor: extract runtime Core into scripts/core.ts; runtime.mjs becomes a thin shell

Core exposes buildIndex/searchText/executeQuery/executeAttune as the single shared
implementation for all transports. First TypeScript module, run via Node type
stripping in dev. Adds typescript-eslint. lint/typecheck green, test 107/107.

scripts/core.ts

@@ -0,0 +1,64 @@
+// Obelisk Core (see docs/adr/0003-core-typescript-esm-precompiled.md).
+//
+// The single shared implementation behind every transport. runtime.mjs (skill),
+// and later the CLI and MCP server, are thin shells over these four functions;
+// none of them re-implement retrieval or own the DB lifecycle.
+//
+// Authored in TypeScript with erasable-only syntax so Node can run it directly
+// via type stripping in development, while the skill artifact ships the tsc
+// output (Phase 6). The heavy internals (db/indexer/query) remain .mjs for now
+// and are migrated in later phases; Core is the typed seam over them.
+
+import { createContext, runInNewContext } from 'node:vm';
+
+import { DB_PATH, openDb } from './db.mjs';
+import { buildIndex } from './indexer.mjs';
+import { createQueryApi, createAttuneApi } from './query.mjs';
+
+export { buildIndex, DB_PATH };
+
+type SandboxApi = Record<string, unknown>;
+
+// Run a user-supplied CodeAct script inside the query/attune sandbox. The script
+// body runs as an async IIFE with a 30s timeout; its `return` value is resolved.
+function runInSandbox(api: SandboxApi, scriptContent: string): Promise<unknown> {
+  const sandbox = {
+    ...api, JSON, Math, Array, Object, Set, Map, Date, RegExp,
+    parseInt, parseFloat, String, Number, Boolean, Error, Promise, console, setTimeout,
+  };
+  const ctx = createContext(sandbox);
+  return runInNewContext(`(async()=>{${scriptContent}})()`, ctx, { timeout: 30000 });
+}
+
+// FTS search over indexed message text. Refreshes the index, then queries.
+export function searchText(text: string, opts?: Record<string, unknown>): unknown {
+  buildIndex();
+  const db = openDb();
+  try {
+    return createQueryApi(db).search(text, opts);
+  } finally {
+    db.close();
+  }
+}
+
+// Execute a read-only CodeAct query script and resolve its returned value.
+export async function executeQuery(scriptContent: string): Promise<unknown> {
+  buildIndex();
+  const db = openDb();
+  try {
+    return await runInSandbox(createQueryApi(db), scriptContent);
+  } finally {
+    db.close();
+  }
+}
+
+// Execute a memory-mutation CodeAct script (remember/forget only).
+export async function executeAttune(scriptContent: string): Promise<unknown> {
+  buildIndex();
+  const db = openDb();
+  try {
+    return await runInSandbox(createAttuneApi(db), scriptContent);
+  } finally {
+    db.close();
+  }
+}

scripts/runtime.mjs

@@ -1,32 +1,16 @@
 #!/usr/bin/env node
+// Skill transport: a thin CLI shell over Obelisk Core (scripts/core.ts).
+// It only parses args, reads script files, prints JSON, and owns the uniform
+// { error, stack } + exit-1 error envelope. All logic lives in Core.
+
 import { createRequire } from 'node:module';
 const require = createRequire(import.meta.url);
 const fs = require('node:fs');
 const path = require('node:path');
-const vm = require('node:vm');
 
-import { DB_PATH, openDb } from './db.mjs';
-import { buildIndex } from './indexer.mjs';
-import { createQueryApi, createAttuneApi } from './query.mjs';
+import { DB_PATH, buildIndex, searchText, executeQuery, executeAttune } from './core.ts';
 
-function executeScript(api, scriptContent) {
-  const sandbox = {
-    ...api, JSON, Math, Array, Object, Set, Map, Date, RegExp,
-    parseInt, parseFloat, String, Number, Boolean, Error, Promise, console, setTimeout,
-  };
-  const ctx = vm.createContext(sandbox);
-  return vm.runInNewContext(`(async()=>{${scriptContent}})()`, ctx, { timeout: 30000 });
-}
-
-function executeQuery(db, scriptContent) {
-  return executeScript(createQueryApi(db), scriptContent);
-}
-
-function executeAttune(db, scriptContent) {
-  return executeScript(createAttuneApi(db), scriptContent);
-}
-
-function main() {
+async function main() {
   const args = process.argv.slice(2);
   // Uniform error envelope across all four verbs: a failure is reported as
   // { error, stack } on stdout with exit code 1, never a raw crash on stderr.
@@ -34,6 +18,8 @@ function main() {
     process.stdout.write(JSON.stringify({ error: e.message, stack: e.stack }) + '\n');
     process.exitCode = 1;
   };
+  const emit = (r) => process.stdout.write(JSON.stringify(r, null, 2) + '\n');
+
   if (args[0] === '--build') {
     try {
       buildIndex({ force: true });
@@ -42,34 +28,15 @@ function main() {
     return;
   }
   if (args[0] === '--search' && args[1]) {
-    let db;
-    try {
-      buildIndex();
-      db = openDb();
-      process.stdout.write(JSON.stringify(createQueryApi(db).search(args.slice(1).join(' ')), null, 2) + '\n');
-    } catch (e) {
-      fail(e);
-    } finally {
-      if (db) db.close();
-    }
+    try { emit(searchText(args.slice(1).join(' '))); } catch (e) { fail(e); }
     return;
   }
   if (args[0] === '--query' && args[1]) {
-    buildIndex();
-    const db = openDb();
-    const script = fs.readFileSync(path.resolve(args[1]), 'utf8');
-    executeQuery(db, script)
-      .then(r => { process.stdout.write(JSON.stringify(r, null, 2) + '\n'); db.close(); })
-      .catch(e => { process.stdout.write(JSON.stringify({ error: e.message, stack: e.stack }) + '\n'); db.close(); process.exitCode = 1; });
+    try { emit(await executeQuery(fs.readFileSync(path.resolve(args[1]), 'utf8'))); } catch (e) { fail(e); }
     return;
   }
   if (args[0] === '--attune' && args[1]) {
-    buildIndex();
-    const db = openDb();
-    const script = fs.readFileSync(path.resolve(args[1]), 'utf8');
-    executeAttune(db, script)
-      .then(r => { process.stdout.write(JSON.stringify(r, null, 2) + '\n'); db.close(); })
-      .catch(e => { process.stdout.write(JSON.stringify({ error: e.message, stack: e.stack }) + '\n'); db.close(); process.exitCode = 1; });
+    try { emit(await executeAttune(fs.readFileSync(path.resolve(args[1]), 'utf8'))); } catch (e) { fail(e); }
     return;
   }
   process.stderr.write('Usage:\n  node runtime.mjs --build\n  node runtime.mjs --search "text"\n  node runtime.mjs --query <file.js>\n  node runtime.mjs --attune <file.js>\n');