fix(observe): Claude Code hook must be a single shell-string command (#17)

The installer emitted command:'node' + an args array containing a
${CLAUDE_PROJECT_DIR} template — Claude Code's hooks schema has no args
field and only shell-expands the command string, so node received the
template verbatim and threw MODULE_NOT_FOUND after EVERY tool call in
every linked project (live user report). Re-install replaces legacy
broken entries (marker-based upsert), so 'insta observe install' heals
existing projects.


Claude-Session: https://claude.ai/code/session_01GMbAe5K1RfwaAcge5inX7P

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: tonychang04

src/observe/install.ts

@@ -56,8 +56,11 @@ function materialize(cwd: string, assetDir: string): void {
 }
 
 function claudeEntry(): Group {
-  return { matcher: '*', hooks: [{ type: 'command', command: 'node',
-    args: ['${CLAUDE_PROJECT_DIR}/.insta/observe/hook.js'], timeout: 15, _insta: MARKER }] }
+  // Claude Code executes `command` as ONE shell string with $CLAUDE_PROJECT_DIR in the env —
+  // there is no `args` field in its hooks schema, so a ${…} template in args reaches node
+  // verbatim and throws MODULE_NOT_FOUND after every tool call.
+  return { matcher: '*', hooks: [{ type: 'command',
+    command: 'node "$CLAUDE_PROJECT_DIR/.insta/observe/hook.js"', timeout: 15, _insta: MARKER }] }
 }
 function codexEntry(cwd: string): Group {
   const abs = join(cwd, '.insta', 'observe', 'hook.js') // Codex doesn't expand ${CLAUDE_PROJECT_DIR}; use an absolute path

test/observe-install.test.ts

@@ -0,0 +1,40 @@
+// The Claude Code hooks schema executes `command` as ONE shell string ($CLAUDE_PROJECT_DIR is an
+// env var the shell expands). The installer used to emit command:'node' + an args array with a
+// ${CLAUDE_PROJECT_DIR} template — nothing expands it, so node threw MODULE_NOT_FOUND after EVERY
+// tool call in every linked project. Found live (user report, 2026-07-12).
+import { test, expect } from 'vitest'
+import { mkdtempSync, readFileSync, mkdirSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { installObserve } from '../src/observe/install.js'
+
+function fakeAssets(): string {
+  const d = mkdtempSync(join(tmpdir(), 'obs-assets-'))
+  writeFileSync(join(d, 'hook.js'), '// hook')
+  writeFileSync(join(d, 'scanner.js'), '// scanner')
+  return d
+}
+
+test('claude hook entry is a single shell-string command with $CLAUDE_PROJECT_DIR (no args array)', () => {
+  const cwd = mkdtempSync(join(tmpdir(), 'obs-proj-'))
+  mkdirSync(join(cwd, '.claude'), { recursive: true })
+  installObserve({ cwd, assetDir: fakeAssets() })
+  const settings = JSON.parse(readFileSync(join(cwd, '.claude', 'settings.json'), 'utf8'))
+  const hook = settings.hooks.PostToolUse.at(-1).hooks[0]
+  expect(hook.args).toBeUndefined()
+  expect(hook.command).toBe('node "$CLAUDE_PROJECT_DIR/.insta/observe/hook.js"')
+})
+
+test('re-install replaces a broken legacy args-array entry instead of stacking', () => {
+  const cwd = mkdtempSync(join(tmpdir(), 'obs-proj-'))
+  mkdirSync(join(cwd, '.claude'), { recursive: true })
+  writeFileSync(join(cwd, '.claude', 'settings.json'), JSON.stringify({
+    hooks: { PostToolUse: [{ matcher: '*', hooks: [{ type: 'command', command: 'node',
+      args: ['${CLAUDE_PROJECT_DIR}/.insta/observe/hook.js'], _insta: 'insta-observe' }] }] },
+  }))
+  installObserve({ cwd, assetDir: fakeAssets() })
+  const settings = JSON.parse(readFileSync(join(cwd, '.claude', 'settings.json'), 'utf8'))
+  const all = settings.hooks.PostToolUse.flatMap((g: any) => g.hooks)
+  expect(all).toHaveLength(1)
+  expect(all[0].args).toBeUndefined()
+})