TASK METADATA

Target Files: infra/setup.ts, infra/setup/cli.ts, infra/setup/compose.ts, infra/setup/env.ts
Core Objective: Phase 4 (Infrastructure Scripts Refactoring): Decompose the monolithic 1,021-line infra/setup.ts installer into modular sub-modules under infra/setup/ separating CLI interactive prompts, Docker compose generation, and environment file management.
Dependencies: tasks/new/2026-0825.01.jul.story.arch.monolith-decomposition-roadmap-1845.md
Additional Important Notes: Must verify with deno check infra/setup.ts and ensure dry-run generation produces identical compose and env files.

Risks:
- Generating corrupted docker-compose.yml or .env files if template strings or formatting helpers are incorrectly moved.
Alternatives:
- Keeping setup.ts as a single monolithic script; rejected due to maintenance difficulty and cognitive overload.

Extract Modular Setup Sub-modules (infra/setup/):
- infra/setup/cli.ts: Extract interactive command-line prompts, flags parsing, and user confirmation dialogs.
- infra/setup/compose.ts: Extract Docker compose YAML string generation and network/volume configuration.
- infra/setup/env.ts: Extract .env file generation, cryptographic secret generation (keys, salts, PRF secrets), and domain configuration.
Refactor infra/setup.ts:
- Keep infra/setup.ts as the clean CLI runner that orchestrates the extracted modules.
Quality Gates & Validation:
- Run deno check infra/setup.ts.
- Run deno fmt infra/ and verify generated configs against dummy test parameters.