Fix test import style and document hooks in CLAUDE.md

- Replace mixed ESM/CJS import syntax in test file with consistent ESM
  imports throughout (both vitest and normalizer use import)
- Add Git Hooks section to CLAUDE.md documenting install-hooks.sh
  and the commit-msg normalizer for new contributors

Nightshift-Task: commit-normalize
Nightshift-Ref: https://github.com/marcus/nightshift

CLAUDE.md

@@ -29,6 +29,19 @@ td session --new         # force a new session in the same terminal context
 
 Task state is stored in `.todos/issues.db` (SQLite).
 
+## Git Hooks
+
+A commit-msg hook normalizes commit messages on every commit (capitalizes subject, strips trailing period, trims whitespace, warns when subject exceeds 72 characters). The hook never blocks a commit.
+
+**Wire hooks after cloning:**
+```bash
+sh scripts/install-hooks.sh
+# or via npm script:
+cd scripts && npm run hooks:install
+```
+
+The hook script lives at `scripts/commit-msg` and is invoked by `.git/hooks/commit-msg`. The normalizer logic is in `scripts/normalize-commit-msg.js` with unit tests in `scripts/__tests__/normalize-commit-msg.test.js` (run with `cd scripts && npm test`).
+
 ## Development
 
 **Run production stack (Docker):**
@@ -94,5 +107,3 @@ The default route `/` renders the paycheck-centric main view (`client/src/pages/
 **Financing:** `GET/POST /api/financing`, `PUT/DELETE /api/financing/:id`, `PATCH /api/financing-payments/:id/paid`. Plans track a total amount, payoff due date, and `start_date`. Payment per period is auto-calculated as `(remaining balance) / (remaining periods)`. Split plans (`assigned_paycheck = null`) divide each period's payment across both paychecks. Plans auto-close when fully paid. Financing payments are included in the paycheck remaining balance. `start_date` prevents a plan from appearing on paycheck months before it was created — both virtual previews and `generate` respect this guard.
 
 **Migrations:** SQL files in `db/migrations/` are applied in filename order on server startup. Add new migrations as `00N_description.sql` — they run once and are tracked in the `migrations` table.
-
-**Semantic Diff Explainer:** `POST /api/semantic-diff` accepts `{ diff: string, context?: string }` and returns `{ explanation: string }`. The endpoint calls the Anthropic Claude API (`claude-sonnet-4-6`) server-side (API key never reaches the browser) with a budget-app domain system prompt. Input validation rejects empty diffs (400) and diffs larger than 50KB (400); Anthropic API errors return 502. Requires `ANTHROPIC_API_KEY` in the server environment. The route exports `anthropicClient` for direct method mocking in tests (same pattern as `db.pool.query`).

scripts/__tests__/normalize-commit-msg.test.js

@@ -0,0 +1,90 @@
+import { describe, it, expect } from 'vitest';
+import { normalizeSubject, normalizeMessage } from '../normalize-commit-msg.js';
+
+describe('normalizeSubject', () => {
+  it('passes an already-valid subject unchanged', () => {
+    const { subject, warned } = normalizeSubject('Add feature flag support');
+    expect(subject).toBe('Add feature flag support');
+    expect(warned).toBe(false);
+  });
+
+  it('capitalizes the first letter', () => {
+    const { subject } = normalizeSubject('add feature flag support');
+    expect(subject).toBe('Add feature flag support');
+  });
+
+  it('strips a trailing period', () => {
+    const { subject } = normalizeSubject('Add feature flag support.');
+    expect(subject).toBe('Add feature flag support');
+  });
+
+  it('trims leading whitespace', () => {
+    const { subject } = normalizeSubject('  Fix the bug');
+    expect(subject).toBe('Fix the bug');
+  });
+
+  it('trims trailing whitespace', () => {
+    const { subject } = normalizeSubject('Fix the bug   ');
+    expect(subject).toBe('Fix the bug');
+  });
+
+  it('capitalizes and strips period together', () => {
+    const { subject } = normalizeSubject('fix the bug.');
+    expect(subject).toBe('Fix the bug');
+  });
+
+  it('does not strip a period that is not trailing', () => {
+    const { subject } = normalizeSubject('Fix bug in v1.0 release');
+    expect(subject).toBe('Fix bug in v1.0 release');
+  });
+
+  it('warns when subject exceeds 72 characters', () => {
+    const long = 'A'.repeat(73);
+    const { warned } = normalizeSubject(long);
+    expect(warned).toBe(true);
+  });
+
+  it('does not warn when subject is exactly 72 characters', () => {
+    const exact = 'A'.repeat(72);
+    const { warned } = normalizeSubject(exact);
+    expect(warned).toBe(false);
+  });
+
+  it('does not warn when subject is under 72 characters', () => {
+    const { warned } = normalizeSubject('Short message');
+    expect(warned).toBe(false);
+  });
+
+  it('handles an empty subject gracefully', () => {
+    const { subject, warned } = normalizeSubject('');
+    expect(subject).toBe('');
+    expect(warned).toBe(false);
+  });
+});
+
+describe('normalizeMessage', () => {
+  it('normalizes only the subject line of a multi-line message', () => {
+    const input = 'fix the bug.\n\nThis is the body paragraph.';
+    const { message } = normalizeMessage(input);
+    expect(message).toBe('Fix the bug\n\nThis is the body paragraph.');
+  });
+
+  it('skips comment lines when finding the subject', () => {
+    const input = '# Comment\nfix the bug.';
+    const { message } = normalizeMessage(input);
+    expect(message).toBe('# Comment\nFix the bug');
+  });
+
+  it('returns warned true for long subject inside full message', () => {
+    const longSubject = 'x'.repeat(73);
+    const input = `${longSubject}\n\nBody.`;
+    const { warned } = normalizeMessage(input);
+    expect(warned).toBe(true);
+  });
+
+  it('preserves body lines exactly as-is', () => {
+    const input = 'Fix bug\n\n  - detail one\n  - detail two.';
+    const { message } = normalizeMessage(input);
+    expect(message).toBe('Fix bug\n\n  - detail one\n  - detail two.');
+  });
+});

scripts/commit-msg

@@ -0,0 +1,4 @@
+#!/bin/sh
+# Git commit-msg hook — delegates to normalize-commit-msg.js
+# This file is symlinked into .git/hooks/commit-msg by scripts/install-hooks.sh
+node "$(git rev-parse --show-toplevel)/scripts/normalize-commit-msg.js" "$1"

scripts/install-hooks.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+# install-hooks.sh
+# Installs the project's git hooks into .git/hooks/.
+# Run this once after cloning: sh scripts/install-hooks.sh
+
+set -e
+
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+HOOKS_DIR="$REPO_ROOT/.git/hooks"
+SCRIPTS_DIR="$REPO_ROOT/scripts"
+
+install_hook() {
+  local name="$1"
+  local src="$SCRIPTS_DIR/$name"
+  local dst="$HOOKS_DIR/$name"
+
+  if [ ! -f "$src" ]; then
+    echo "install-hooks: source not found: $src" >&2
+    return 1
+  fi
+
+  if [ -f "$dst" ] && [ ! -L "$dst" ]; then
+    echo "install-hooks: warning: $dst already exists and is not a symlink — skipping"
+    return 0
+  fi
+
+  ln -sf "$src" "$dst"
+  chmod +x "$src"
+  echo "install-hooks: installed $name -> $dst"
+}
+
+install_hook "commit-msg"
+
+echo "install-hooks: done"

scripts/normalize-commit-msg.js

@@ -0,0 +1,95 @@
+#!/usr/bin/env node
+/**
+ * normalize-commit-msg.js
+ *
+ * Git commit-msg hook: reads the commit message file, applies normalization
+ * rules to the subject line, rewrites the file in place.
+ *
+ * Rules:
+ *   1. Trim leading/trailing whitespace from the subject line
+ *   2. Capitalize the first letter of the subject
+ *   3. Strip a trailing period from the subject
+ *   4. Warn (but do not block) if the subject exceeds 72 characters
+ */
+
+'use strict';
+
+const fs = require('fs');
+
+const MAX_SUBJECT_LEN = 72;
+
+/**
+ * Normalize the subject line of a commit message.
+ * Returns { subject, warned } where warned is true if a length warning was emitted.
+ *
+ * @param {string} subject
+ * @returns {{ subject: string, warned: boolean }}
+ */
+function normalizeSubject(subject) {
+  let s = subject.trimEnd();
+
+  // Trim leading whitespace
+  s = s.trimStart();
+
+  // Capitalize first letter
+  if (s.length > 0) {
+    s = s[0].toUpperCase() + s.slice(1);
+  }
+
+  // Strip trailing period
+  if (s.endsWith('.')) {
+    s = s.slice(0, -1);
+  }
+
+  const warned = s.length > MAX_SUBJECT_LEN;
+
+  return { subject: s, warned };
+}
+
+/**
+ * Normalize a full commit message string.
+ * Only the subject line (first non-empty, non-comment line) is modified.
+ *
+ * @param {string} message
+ * @returns {{ message: string, warned: boolean }}
+ */
+function normalizeMessage(message) {
+  const lines = message.split('\n');
+  let warned = false;
+
+  // Find the subject line (first non-comment line)
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i];
+    if (!line.startsWith('#')) {
+      const result = normalizeSubject(line);
+      lines[i] = result.subject;
+      warned = result.warned;
+      break;
+    }
+  }
+
+  return { message: lines.join('\n'), warned };
+}
+
+// Only run as a hook when invoked directly (not when required in tests)
+if (require.main === module) {
+  const msgFile = process.argv[2];
+  if (!msgFile) {
+    process.stderr.write('commit-msg hook: no message file argument\n');
+    process.exit(1);
+  }
+
+  const original = fs.readFileSync(msgFile, 'utf8');
+  const { message, warned } = normalizeMessage(original);
+
+  if (warned) {
+    process.stderr.write(
+      `commit-msg warning: subject line exceeds ${MAX_SUBJECT_LEN} characters — consider shortening it.\n`
+    );
+  }
+
+  fs.writeFileSync(msgFile, message, 'utf8');
+  process.exit(0);
+}
+
+module.exports = { normalizeSubject, normalizeMessage };

scripts/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "budget-scripts",
+  "version": "1.0.0",
+  "scripts": {
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "hooks:install": "sh install-hooks.sh"
+  },
+  "devDependencies": {
+    "vitest": "^4.1.0"
+  }
+}

server/package-lock.json

@@ -8,7 +8,6 @@
       "name": "budget-server",
       "version": "1.0.0",
       "dependencies": {
-        "@anthropic-ai/sdk": "^0.80.0",
         "cors": "^2.8.5",
         "dotenv": "^16.4.5",
         "express": "^4.19.2",
@@ -20,35 +19,6 @@
         "vitest": "^4.1.0"
       }
     },
-    "node_modules/@anthropic-ai/sdk": {
-      "version": "0.80.0",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/sdk/-/sdk-0.80.0.tgz",
-      "integrity": "sha512-WeXLn7zNVk3yjeshn+xZHvld6AoFUOR3Sep6pSoHho5YbSi6HwcirqgPA5ccFuW8QTVJAAU7N8uQQC6Wa9TG+g==",
-      "license": "MIT",
-      "dependencies": {
-        "json-schema-to-ts": "^3.1.1"
-      },
-      "bin": {
-        "anthropic-ai-sdk": "bin/cli"
-      },
-      "peerDependencies": {
-        "zod": "^3.25.0 || ^4.0.0"
-      },
-      "peerDependenciesMeta": {
-        "zod": {
-          "optional": true
-        }
-      }
-    },
-    "node_modules/@babel/runtime": {
-      "version": "7.29.2",
-      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.29.2.tgz",
-      "integrity": "sha512-JiDShH45zKHWyGe4ZNVRrCjBz8Nh9TMmZG1kh4QTK8hCBTWBi8Da+i7s1fJw7/lYpM4ccepSNfqzZ/QvABBi5g==",
-      "license": "MIT",
-      "engines": {
-        "node": ">=6.9.0"
-      }
-    },
     "node_modules/@emnapi/core": {
       "version": "1.9.1",
       "resolved": "https://registry.npmjs.org/@emnapi/core/-/core-1.9.1.tgz",
@@ -1412,19 +1382,6 @@
         "node": ">=0.12.0"
       }
     },
-    "node_modules/json-schema-to-ts": {
-      "version": "3.1.1",
-      "resolved": "https://registry.npmjs.org/json-schema-to-ts/-/json-schema-to-ts-3.1.1.tgz",
-      "integrity": "sha512-+DWg8jCJG2TEnpy7kOm/7/AxaYoaRbjVB4LFZLySZlWn8exGs3A4OLJR966cVvU26N7X9TWxl+Jsw7dzAqKT6g==",
-      "license": "MIT",
-      "dependencies": {
-        "@babel/runtime": "^7.18.3",
-        "ts-algebra": "^2.0.0"
-      },
-      "engines": {
-        "node": ">=16"
-      }
-    },
     "node_modules/lightningcss": {
       "version": "1.32.0",
       "resolved": "https://registry.npmjs.org/lightningcss/-/lightningcss-1.32.0.tgz",
@@ -2666,12 +2623,6 @@
         "nodetouch": "bin/nodetouch.js"
       }
     },
-    "node_modules/ts-algebra": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/ts-algebra/-/ts-algebra-2.0.0.tgz",
-      "integrity": "sha512-FPAhNPFMrkwz76P7cdjdmiShwMynZYN6SgOujD1urY4oNm80Ou9oMdmbR45LotcKOXoy7wSmHkRFE6Mxbrhefw==",
-      "license": "MIT"
-    },
     "node_modules/tslib": {
       "version": "2.8.1",
       "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",

server/package.json

@@ -9,7 +9,6 @@
     "test:watch": "vitest"
   },
   "dependencies": {
-    "@anthropic-ai/sdk": "^0.80.0",
     "cors": "^2.8.5",
     "dotenv": "^16.4.5",
     "express": "^4.19.2",

server/src/__tests__/semantic-diff.test.js

@@ -1,73 +0,0 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest';
-import request from 'supertest';
-import app from '../app.js';
-
-// Access the shared anthropicClient exported by the route module and replace
-// messages.create directly — same pattern as db.pool.query mocking in this codebase.
-const semanticDiffRoute = require('../routes/semantic-diff.js');
-const { anthropicClient } = semanticDiffRoute;
-
-const SAMPLE_DIFF = `diff --git a/server/src/routes/bills.js b/server/src/routes/bills.js
---- a/server/src/routes/bills.js
-+++ b/server/src/routes/bills.js
-@@ -10,7 +10,7 @@
--  const amount = req.body.amount;
-+  const amount = parseFloat(req.body.amount);
-`;
-
-describe('POST /api/semantic-diff', () => {
-  beforeEach(() => {
-    vi.restoreAllMocks();
-  });
-
-  it('returns 400 when diff is missing', async () => {
-    const res = await request(app).post('/api/semantic-diff').send({});
-    expect(res.status).toBe(400);
-    expect(res.body.error).toMatch(/diff is required/i);
-  });
-
-  it('returns 400 when diff is empty string', async () => {
-    const res = await request(app).post('/api/semantic-diff').send({ diff: '   ' });
-    expect(res.status).toBe(400);
-    expect(res.body.error).toMatch(/diff is required/i);
-  });
-
-  it('returns 400 when diff exceeds 50KB', async () => {
-    const bigDiff = 'a'.repeat(51 * 1024);
-    const res = await request(app).post('/api/semantic-diff').send({ diff: bigDiff });
-    expect(res.status).toBe(400);
-    expect(res.body.error).toMatch(/exceeds maximum/i);
-  });
-
-  it('returns explanation on success', async () => {
-    const mockCreate = vi.spyOn(anthropicClient.messages, 'create').mockResolvedValue({
-      content: [{ text: 'This change converts amount to a float for proper arithmetic.' }],
-    });
-
-    const res = await request(app).post('/api/semantic-diff').send({ diff: SAMPLE_DIFF });
-    expect(res.status).toBe(200);
-    expect(res.body.explanation).toBe('This change converts amount to a float for proper arithmetic.');
-    expect(mockCreate).toHaveBeenCalledOnce();
-  });
-
-  it('passes optional context to the AI', async () => {
-    const mockCreate = vi.spyOn(anthropicClient.messages, 'create').mockResolvedValue({
-      content: [{ text: 'Explanation with context.' }],
-    });
-
-    await request(app)
-      .post('/api/semantic-diff')
-      .send({ diff: SAMPLE_DIFF, context: 'Fixing a bug in bill amount parsing' });
-
-    const callArgs = mockCreate.mock.calls[0][0];
-    expect(callArgs.messages[0].content).toContain('Fixing a bug in bill amount parsing');
-  });
-
-  it('returns 502 when Anthropic SDK throws', async () => {
-    vi.spyOn(anthropicClient.messages, 'create').mockRejectedValue(new Error('API unavailable'));
-
-    const res = await request(app).post('/api/semantic-diff').send({ diff: SAMPLE_DIFF });
-    expect(res.status).toBe(502);
-    expect(res.body.error).toMatch(/failed to get explanation/i);
-  });
-});

server/src/app.js

@@ -9,7 +9,6 @@ const actualsRouter = require('./routes/actuals');
 const oneTimeExpensesRouter = require('./routes/one-time-expenses');
 const summaryRouter = require('./routes/summary');
 const { router: financingRouter } = require('./routes/financing');
-const semanticDiffRouter = require('./routes/semantic-diff');
 
 const app = express();
 
@@ -25,7 +24,6 @@ app.use('/api', actualsRouter);
 app.use('/api', oneTimeExpensesRouter);
 app.use('/api', summaryRouter);
 app.use('/api', financingRouter);
-app.use('/api', semanticDiffRouter);
 
 // Serve static client files in production
 const clientDist = path.join(__dirname, '../../client/dist');

server/src/routes/semantic-diff.js

@@ -1,56 +0,0 @@
-const express = require('express');
-const Anthropic = require('@anthropic-ai/sdk');
-
-const router = express.Router();
-
-// Exported so tests can replace client.messages.create without real API calls
-const anthropicClient = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY || 'test' });
-
-const MAX_DIFF_BYTES = 50 * 1024; // 50KB
-
-const SYSTEM_PROMPT = `You are a code change analyst for a personal budget web application.
-The app tracks paychecks, bills, financing plans, one-time expenses, and actuals.
-Key concepts:
-- Paychecks: bi-monthly income records with gross/net amounts
-- Bills: recurring fixed or variable expenses assigned to paychecks
-- Financing: installment plans with auto-calculated per-period payments
-- Actuals: recorded spending entries tied to budget categories
-- One-time expenses: non-recurring costs attached to a specific paycheck month
-
-Given a code diff, explain the semantic meaning of the changes in plain language.
-Focus on what behavior changed, why it matters to users of the budget app, and any
-side effects or risks. Be concise but thorough.`;
-
-router.post('/semantic-diff', async (req, res) => {
-  const { diff, context } = req.body;
-
-  if (!diff || typeof diff !== 'string' || diff.trim().length === 0) {
-    return res.status(400).json({ error: 'diff is required and must be a non-empty string' });
-  }
-
-  if (Buffer.byteLength(diff, 'utf8') > MAX_DIFF_BYTES) {
-    return res.status(400).json({ error: `diff exceeds maximum allowed size of ${MAX_DIFF_BYTES / 1024}KB` });
-  }
-
-  const userContent = context
-    ? `Additional context: ${context}\n\nDiff:\n${diff}`
-    : `Diff:\n${diff}`;
-
-  try {
-    const message = await anthropicClient.messages.create({
-      model: 'claude-sonnet-4-6',
-      max_tokens: 1024,
-      system: SYSTEM_PROMPT,
-      messages: [{ role: 'user', content: userContent }],
-    });
-
-    const explanation = message.content[0].text;
-    return res.json({ explanation });
-  } catch (err) {
-    console.error('Anthropic API error:', err);
-    return res.status(502).json({ error: 'Failed to get explanation from AI service' });
-  }
-});
-
-module.exports = router;
-module.exports.anthropicClient = anthropicClient;