Claude Code CLI : The Terminal Is the New IDE

    
bash installation
# Step 1: Install globally
npm install -g @anthropic-ai/claude-code
 
# Step 2: Verify the binary is on your PATH
which claude          # /usr/local/bin/claude  (macOS/Linux)
claude --version      # claude-code 1.x.x
 
# Step 3: Authenticate (first run only)
claude
# → Opens a browser tab for OAuth login to your Anthropic account
# → Stores credentials in ~/.claude/credentials.json
# → Session token is refreshed automatically

shell entering the REPL
$ cd ~/projects/payments-service
$ claude
 
╭─────────────────────────────────────────────────╮
│  Claude Code  v1.2.0  (claude-3-5-sonnet)        │
│  Context: ~/projects/payments-service            │
│  Type /help for commands, Ctrl+C to exit         │
╰─────────────────────────────────────────────────╯
 
> _

repl slash commands reference
/help          # Show all available commands
/clear         # Reset conversation context (new task, fresh memory)
/compact       # Summarize history to save token budget
/cost          # Show API token usage and estimated cost for this session
/diff          # Show pending file changes as a unified diff
/undo          # Revert the last file operation Claude performed
/review        # Request Claude to critique its own last output
/exit          # Exit the REPL cleanly

claude repl reconnaissance output
> How many places in this codebase reference the 'name' column on the users table?
  Include raw SQL, ORM queries, and TypeScript types.
 
[Claude scans: src/, migrations/, tests/, types/]
 
Found references to `users.name` in 14 locations:
  src/models/User.ts           line 12, 47
  src/resolvers/userResolver.ts line 23, 89, 134
  src/services/authService.ts   line 56
  src/api/routes/user.ts        line 18, 34
  migrations/001_create_users.ts line 8
  tests/unit/user.test.ts       line 44, 78, 102
  tests/integration/auth.test.ts line 29
 
Recommended migration order:
  1. Write migration with backward-compatible column add
  2. Update TypeScript types and models
  3. Update resolvers and services
  4. Update and re-run tests
  5. Drop old column in a follow-up migration

claude repl migration generation
> Generate a backward-compatible Knex migration that:
  1. Adds first_name and last_name columns (NOT NULL with defaults)
  2. Backfills them by splitting the existing name column on the first space
  3. Does NOT drop the name column yet (zero-downtime: keep both live)
 
[Proposal] Create: migrations/002_split_user_name.ts
 
  export async function up(knex: Knex): Promise<void> {
    await knex.schema.table('users', (table) => {
      table.string('first_name', 100).notNullable().defaultTo('');
      table.string('last_name',  100).notNullable().defaultTo('');
    });
    // Backfill: split on first space, remainder goes to last_name
    await knex.raw(`
      UPDATE users
      SET
        first_name = SPLIT_PART(name, ' ', 1),
        last_name  = NULLIF(TRIM(SUBSTRING(name FROM POSITION(' ' IN name))), '')
    `);
  }
 
  export async function down(knex: Knex): Promise<void> {
    await knex.schema.table('users', (table) => {
      table.dropColumn('first_name');
      table.dropColumn('last_name');
    });
  }
 
[System] Write this file? (y/n): y
✓ Written: migrations/002_split_user_name.ts

claude repl type update + compile check
> Update the User type in src/types/User.ts to add first_name and last_name.
  Keep the name field for now (backward compat). Then run tsc --noEmit to verify.
 
[Proposal] Edit: src/types/User.ts
  + first_name: string;
  + last_name: string;
    name: string;   // deprecated will be removed in v2.1
 
[System] Apply edit? (y/n): y
✓ Edited: src/types/User.ts
 
[Running] npx tsc --noEmit
 
src/resolvers/userResolver.ts(89,5): error TS2339:
  Property 'fullName' does not exist on type 'User'.
 
Found 1 type error. Fixing automatically...
 
[Proposal] Edit: src/resolvers/userResolver.ts line 89
  - return user.fullName;
  + return `${user.first_name} ${user.last_name}`.trim();
 
[System] Apply fix? (y/n): y
✓ Fixed. Re-running tsc --noEmit...
✓ Compilation clean. 0 errors.

claude repl test fixing loop
> Run the test suite. Fix any failures related to the name → first_name/last_name change.
 
[Running] npm test
 
FAIL  tests/unit/user.test.ts
  ● User model › should return full name
    Expected: 'Jane Doe'
    Received: undefined
 
  ● Auth service › should greet user by name
    Expected: 'Hello Jane'
    Received: 'Hello undefined'
 
2 tests failed. Analyzing failures...
 
Root cause: tests are reading user.name but fixture objects now need first_name/last_name.
 
[Proposal] Edit: tests/unit/user.test.ts
  - const user = { name: 'Jane Doe', email: '[email protected]' };
  + const user = { first_name: 'Jane', last_name: 'Doe', name: 'Jane Doe', email: '[email protected]' };
 
[Proposal] Edit: tests/integration/auth.test.ts
  - expect(response.body.greeting).toBe(`Hello ${user.name.split(' ')[0]}`);
  + expect(response.body.greeting).toBe(`Hello ${user.first_name}`);
 
[System] Apply both edits? (y/n): y
✓ Edits applied. Re-running tests...
 
PASS  tests/unit/user.test.ts       (12 tests, 0 failed)
PASS  tests/integration/auth.test.ts (8 tests, 0 failed)
✓ All tests passing.