diff --git a/packages/deploy/src/extract-agent.ts b/packages/deploy/src/extract-agent.ts
index 7c050630..b3d30c00 100644
--- a/packages/deploy/src/extract-agent.ts
+++ b/packages/deploy/src/extract-agent.ts
@@ -13,7 +13,8 @@ import {
   assertReadableFile,
   extractDefaultExport,
   packageNodePaths,
-  preserveLocalImportMetaUrlPlugin
+  preserveLocalImportMetaUrlPlugin,
+  withUnresolvedImportHint
 } from './persona-source.js';
 
 /**
@@ -107,6 +108,8 @@ export async function extractAgentSpec(onEventPath: string): Promise<ExtractedAg
       resolveExtensions: RESOLVE_EXTENSIONS,
       plugins: [runtimeStubPlugin(), preserveLocalImportMetaUrlPlugin()],
       nodePaths: packageNodePaths(onEventPath)
+    }).catch((err) => {
+      throw withUnresolvedImportHint(err, onEventPath);
     });
 
     const mod = await import(pathToFileURL(compiledPath).href);
diff --git a/packages/deploy/src/persona-source.test.ts b/packages/deploy/src/persona-source.test.ts
new file mode 100644
index 00000000..168717bc
--- /dev/null
+++ b/packages/deploy/src/persona-source.test.ts
@@ -0,0 +1,152 @@
+import assert from 'node:assert/strict';
+import { cp, mkdir, mkdtemp, rm, symlink, writeFile } from 'node:fs/promises';
+import { execFileSync } from 'node:child_process';
+import { createRequire } from 'node:module';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+import { fileURLToPath, pathToFileURL } from 'node:url';
+
+import { nodeModulesChain, packageNodePaths, withUnresolvedImportHint } from './persona-source.js';
+
+const require = createRequire(import.meta.url);
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+
+test('nodeModulesChain treats an ancestor node_modules as a search root', () => {
+  const chain = nodeModulesChain('/prefix/node_modules/@agentworkforce/deploy/dist');
+  assert.ok(
+    chain.includes('/prefix/node_modules'),
+    `installed tree root missing from ${JSON.stringify(chain)}`
+  );
+  assert.ok(
+    !chain.some((dir) => dir.endsWith('node_modules/node_modules')),
+    `doubled node_modules segment in ${JSON.stringify(chain)}`
+  );
+});
+
+test('packageNodePaths searches the persona tree before the CLI tree', () => {
+  const paths = packageNodePaths('/repo/customer-success/app-signal/persona.ts');
+  assert.equal(paths[0], path.join('/repo/customer-success/app-signal', 'node_modules'));
+  assert.equal(new Set(paths).size, paths.length, 'duplicate entries');
+  assert.ok(
+    paths.includes(nodeModulesChain(HERE).find((dir) => dir.endsWith('node_modules')) as string),
+    'this package install root missing'
+  );
+});
+
+test('withUnresolvedImportHint names the missing package and where to install it', () => {
+  const hinted = withUnresolvedImportHint(
+    new Error(
+      'Build failed with 1 error:\npersona.ts:2:30: ERROR: Could not resolve "@agentworkforce/turn-kit"'
+    ),
+    '/repo/customer-success/app-signal/persona.ts'
+  );
+  assert.ok(hinted instanceof Error);
+  assert.match(hinted.message, /npm install @agentworkforce\/turn-kit/);
+  assert.match(hinted.message, /\/repo\/customer-success\/app-signal/);
+});
+
+test('withUnresolvedImportHint installs the package, not the deep import path', () => {
+  const hinted = withUnresolvedImportHint(
+    new Error(
+      [
+        'ERROR: Could not resolve "@relayfile/adapter-core/triggers"',
+        'ERROR: Could not resolve "lodash/fp"'
+      ].join('\n')
+    ),
+    '/repo/persona.ts'
+  ) as Error;
+  assert.match(hinted.message, /npm install @relayfile\/adapter-core lodash$/m);
+});
+
+test('withUnresolvedImportHint quotes shell metacharacters', () => {
+  const hinted = withUnresolvedImportHint(
+    new Error(String.raw`ERROR: Could not resolve "evil; touch pwned"`),
+    "/repo/it's a dir/persona.ts"
+  ) as Error;
+  const command = hinted.message.split('\n').at(-1) as string;
+  assert.equal(command, String.raw`  cd '/repo/it'\''s a dir' && npm install 'evil; touch pwned'`);
+  // Round-trip through a shell to prove the injected command cannot run.
+  assert.deepEqual(
+    execFileSync('/bin/sh', ['-c', `set -- ${command.trim().split('npm install ')[1]}; printf '%s' "$1"`], {
+      encoding: 'utf8'
+    }),
+    'evil; touch pwned'
+  );
+});
+
+test('withUnresolvedImportHint ignores relative imports', () => {
+  const message = 'ERROR: Could not resolve "./missing.js"';
+  const hinted = withUnresolvedImportHint(new Error(message), '/repo/persona.ts');
+  assert.equal((hinted as Error).message, message);
+});
+
+/**
+ * The shipped failure: a globally installed CLI compiling a persona in a repo
+ * that has no `node_modules`. Reproduced by copying the built package into an
+ * installed layout so `import.meta.url` inside persona-source resolves the way
+ * it does for a real `npm i -g agentworkforce`.
+ */
+test('authored persona resolves a CLI-tree package with no project node_modules', async () => {
+  const root = await mkdtemp(path.join(tmpdir(), 'agentworkforce-install-'));
+  const originalCwd = process.cwd();
+  try {
+    const installRoot = path.join(root, 'prefix', 'node_modules');
+    const deployDir = path.join(installRoot, '@agentworkforce', 'deploy');
+    await mkdir(deployDir, { recursive: true });
+    await cp(HERE, path.join(deployDir, 'dist'), { recursive: true });
+    await writeFile(
+      path.join(deployDir, 'package.json'),
+      JSON.stringify({ name: '@agentworkforce/deploy', type: 'module' }),
+      'utf8'
+    );
+    // esbuild is a real dependency of the copied package; link it into the
+    // fake tree so the copy can load at all.
+    await symlink(
+      path.dirname(require.resolve('esbuild/package.json')),
+      path.join(installRoot, 'esbuild')
+    );
+
+    const kitDir = path.join(installRoot, '@agentworkforce', 'persona-kit');
+    await mkdir(kitDir, { recursive: true });
+    await writeFile(
+      path.join(kitDir, 'package.json'),
+      JSON.stringify({ name: '@agentworkforce/persona-kit', type: 'module', main: 'index.js' }),
+      'utf8'
+    );
+    await writeFile(
+      path.join(kitDir, 'index.js'),
+      'export function definePersona(input) { return input; }\n',
+      'utf8'
+    );
+
+    // The persona lives outside the install tree and has no node_modules.
+    const personaDir = path.join(root, 'watchdog-agents', 'customer-success', 'app-signal');
+    await mkdir(personaDir, { recursive: true });
+    const personaPath = path.join(personaDir, 'persona.ts');
+    await writeFile(
+      personaPath,
+      [
+        "import { definePersona } from '@agentworkforce/persona-kit';",
+        '',
+        "export default definePersona({ id: 'app-signal', onEvent: './agent.ts' });",
+        ''
+      ].join('\n'),
+      'utf8'
+    );
+
+    const installed = (await import(
+      pathToFileURL(path.join(deployDir, 'dist', 'persona-source.js')).href
+    )) as typeof import('./persona-source.js');
+
+    // The user's cwd is their own repo, which has no node_modules either —
+    // without this the test's cwd (this monorepo) resolves the import and the
+    // assertion holds even against the broken implementation.
+    process.chdir(personaDir);
+    const result = await installed.loadPersonaSourceFile(personaPath);
+    assert.deepEqual(result.persona, { id: 'app-signal', onEvent: './agent.ts' });
+  } finally {
+    process.chdir(originalCwd);
+    await rm(root, { recursive: true, force: true });
+  }
+});
diff --git a/packages/deploy/src/persona-source.ts b/packages/deploy/src/persona-source.ts
index 73b133b2..c4d6b348 100644
--- a/packages/deploy/src/persona-source.ts
+++ b/packages/deploy/src/persona-source.ts
@@ -2,7 +2,7 @@ import { randomUUID } from 'node:crypto';
 import { builtinModules } from 'node:module';
 import { mkdtemp, readFile, rm, stat } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
-import { dirname, join, resolve } from 'node:path';
+import { basename, dirname, join, resolve } from 'node:path';
 import { fileURLToPath, pathToFileURL } from 'node:url';
 
 import { build, type Loader, type Plugin } from 'esbuild';
@@ -74,6 +74,8 @@ export async function loadPersonaSourceFile(
       resolveExtensions: RESOLVE_EXTENSIONS,
       plugins: [preserveLocalImportMetaUrlPlugin()],
       nodePaths: packageNodePaths(absInput)
+    }).catch((err) => {
+      throw withUnresolvedImportHint(err, absInput);
     });
 
     const mod = await import(pathToFileURL(compiledPath).href);
@@ -106,14 +108,112 @@ function extensionOf(inputPath: string): string {
   return idx === -1 ? '' : normalized.slice(idx);
 }
 
+/**
+ * esbuild `nodePaths` fallbacks for compiling authored `.ts`/`.js` personas
+ * and agents.
+ *
+ * An authored persona lives in the user's own repo, which on a fresh install
+ * usually has no `node_modules` at all — the CLI is installed globally, so
+ * `@agentworkforce/*` exists only inside the CLI's own install tree. esbuild
+ * resolves bare imports by walking up from the importer, so without these
+ * fallbacks `import { definePersona } from '@agentworkforce/persona-kit'`
+ * fails with "Could not resolve".
+ *
+ * Fallbacks are the full `node_modules` lookup chains of (in order) the
+ * persona file, this module (the installed `@agentworkforce/deploy`), and the
+ * cwd. The chain is computed the way Node's own resolver does it, including
+ * the case a naive `join(dir, 'node_modules')` gets wrong: when an ancestor
+ * *is* `node_modules`, that directory is itself the search root. Missing that
+ * produced `<prefix>/node_modules/node_modules` — a path that only exists in
+ * a monorepo checkout, which is why every installed CLI failed here while the
+ * dev layout worked.
+ *
+ * Order matters: the persona's own dependencies win over the CLI's copies,
+ * and every entry is only consulted after normal resolution has failed.
+ */
 export function packageNodePaths(absInput: string): string[] {
   const here = dirname(fileURLToPath(import.meta.url));
-  return [
-    join(dirname(absInput), 'node_modules'),
-    join(here, '..', 'node_modules'),
-    join(here, '..', '..', '..', 'node_modules'),
-    join(process.cwd(), 'node_modules')
-  ];
+  const seen = new Set<string>();
+  const paths: string[] = [];
+  for (const root of [dirname(resolve(absInput)), here, process.cwd()]) {
+    for (const dir of nodeModulesChain(root)) {
+      if (seen.has(dir)) continue;
+      seen.add(dir);
+      paths.push(dir);
+    }
+  }
+  return paths;
+}
+
+/** Every `node_modules` directory Node would search from `fromDir` upward. */
+export function nodeModulesChain(fromDir: string): string[] {
+  const chain: string[] = [];
+  let dir = resolve(fromDir);
+  for (;;) {
+    chain.push(basename(dir) === 'node_modules' ? dir : join(dir, 'node_modules'));
+    const parent = dirname(dir);
+    if (parent === dir) break;
+    dir = parent;
+  }
+  return chain;
+}
+
+/**
+ * Turn esbuild's bare "Could not resolve" into an actionable install hint.
+ *
+ * After `packageNodePaths`, an `@agentworkforce/*` import the CLI ships
+ * resolves on its own; what reaches here is a package neither the project nor
+ * the CLI has (a persona kit the CLI does not depend on, a third-party SDK the
+ * handler imports). Naming it plus the directory to install it in is the
+ * difference between a dead end and a one-line fix.
+ */
+export function withUnresolvedImportHint(error: unknown, absInput: string): unknown {
+  if (!(error instanceof Error)) return error;
+  const missing = unresolvedSpecifiers(error.message);
+  if (missing.length === 0) return error;
+
+  const projectDir = dirname(resolve(absInput));
+  const install = missing.map(shellQuote).join(' ');
+  error.message = [
+    error.message,
+    `Install the missing package${missing.length > 1 ? 's' : ''} where the persona lives:`,
+    `  cd ${shellQuote(projectDir)} && npm install ${install}`
+  ].join('\n');
+  return error;
+}
+
+function unresolvedSpecifiers(message: string): string[] {
+  const found = new Set<string>();
+  for (const match of message.matchAll(/Could not resolve "([^"]+)"/g)) {
+    const specifier = match[1];
+    // Relative/absolute imports are authoring mistakes, not missing installs.
+    if (specifier.startsWith('.') || specifier.startsWith('/')) continue;
+    found.add(packageNameOf(specifier));
+  }
+  return [...found];
+}
+
+/**
+ * The package to install for an import specifier. A deep import
+ * (`@relayfile/adapter-core/triggers`, `lodash/fp`) must be reduced to its
+ * package name — npm reads the full specifier as a local directory or a git
+ * remote and would install the wrong thing, or nothing.
+ */
+function packageNameOf(specifier: string): string {
+  const segments = specifier.split('/');
+  return specifier.startsWith('@') ? segments.slice(0, 2).join('/') : segments[0];
+}
+
+/**
+ * Quote a value for the copy-pasteable `cd … && npm install …` hint. Both the
+ * path and the specifiers originate in the user's own source, but the hint is
+ * written to be pasted into a shell, so a specifier like `x; rm -rf ~` must not
+ * survive as two commands. Ordinary paths and package names are left bare so
+ * the common message stays readable.
+ */
+function shellQuote(value: string): string {
+  if (value.length > 0 && /^[\w@./:+-]+$/.test(value)) return value;
+  return `'${value.split("'").join(`'\\''`)}'`;
 }
 
 export function preserveLocalImportMetaUrlPlugin(): Plugin {