Fixes "PORT" environment variable usage and proposes the "--generate-lib" CLI option

[edouardmercier]

• The generated code does not use the PORT environment variable when the --port CLI is not defined and forces the port to be 3000, while the setupWebServer function port argument already has this default value: proposes to resort to the PORT environment variable in that case.
• Proposes a new --generate-lib CLI option, which causes the generated main() function to be exported and removing the clean-up code generation, so as to be able to import and run than main() function is an existing code, just like a library.

Summary by CodeRabbit

• New Features

  • Added a CLI option to generate library-style output that exposes (rather than auto-invokes) the main entrypoint.

• Refactor

  • Standardized environment variable initialization for more consistent startup.
  • Implemented dynamic port resolution across transports to avoid hard-coded defaults.
  • Centralized startup/cleanup with graceful SIGINT/SIGTERM handling and clearer fatal-error handling.

[coderabbitai]

Walkthrough

Introduces a generateLib option throughout CLI, types, and server code generation. Adds conditional export of main, centralized startup/cleanup with signal handling, dynamic port resolution for transports, and switches dotenv usage to named import with immediate config invocation.

Changes

Cohort / File(s)	Summary of Changes
Server code generation & bootstrap src/generator/server-code.ts	Adds conditional export of main based on options.generateLib; introduces a reusable mainDeclaration containing cleanup() and SIGINT/SIGTERM handlers; centralizes startup sequence and moves previous inline startup/cleanup into the block; replaces dotenv.config() with import { config } from 'dotenv'; config();; implements dynamic port resolution (webServicerPortNumberStatement) and uses it for both web and streamable-http transport setup calls.
CLI option parsing src/index.ts	Adds -l, --generate-lib <boolean> CLI option (parsed to boolean via the existing normalizer) and wires it into parsed CliOptions.
Types update src/types/index.ts	Adds optional generateLib?: boolean to CliOptions with documentation describing library vs. runnable generation.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant U as User (CLI)
  participant C as CLI Parser
  participant G as Code Generator
  participant S as Generated Server
  participant OS as OS Signals

  U->>C: Run generator with options (incl. --generate-lib)
  C->>G: Parsed CliOptions { generateLib, port, ... }
  G->>S: Emit server code (named dotenv import + config(), port resolution, mainDeclaration)

  alt generateLib === false
    note over S: main() defined and invoked
    S->>S: Resolve port (options.port or default)  %% color: #DDEBF7
    S->>S: setupWebServer / setupStreamableHttpServer using resolved port
    S->>OS: Register SIGINT/SIGTERM handlers
    OS-->>S: Signal received
    S->>S: cleanup() then exit
  else generateLib === true
    note over S: main() exported, not invoked
    S-->>U: Library exposes main() for caller control
  end

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

I thump my paw at ports that hide,
A tidy main I now provide.
With signals caught and dotenv primed,
I hop through code that's neatly timed.
Library or run — your call, my friend. 🥕🐇

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The title clearly describes the two primary changes to the generator—correcting the PORT environment variable handling and introducing the --generate-lib CLI option—so it appropriately summarizes the main updates in a concise, topic-focused sentence.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

• 📝 Generate Docstrings

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 2ac9124 and 5ff7f4f.

📒 Files selected for processing (1)

• src/index.ts (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• src/index.ts

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (2)

src/generator/server-code.ts (2)

48-48: Consider simplifying the generated port expression.

The current implementation correctly addresses the PR objective to honor the PORT environment variable when --port is not specified. However, the generated expression could be simplified.

Current generated code when options.port is undefined:

process.env['PORT'] === undefined ? undefined : parseInt(process.env['PORT'], 10)

This can be simplified to:

process.env['PORT'] ? parseInt(process.env['PORT'], 10) : undefined

Apply this diff:

-  const webServicerPortNumberStatement = `${options.port ?? "process.env['PORT'] === undefined ? undefined : parseInt(process.env['PORT'], 10)"}`;
+  const webServicerPortNumberStatement = `${options.port ?? "process.env['PORT'] ? parseInt(process.env['PORT'], 10) : undefined"}`;

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112-113: Acknowledge the dotenv import style change.

The switch from default import to named import is a valid modernization, though this change is not mentioned in the PR objectives.

Both forms work correctly with the dotenv package.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 8ee9fc3 and 2ac9124.

📒 Files selected for processing (3)

• src/generator/server-code.ts (5 hunks)
• src/index.ts (1 hunks)
• src/types/index.ts (1 hunks)

🔇 Additional comments (6)

src/types/index.ts (1)

32-33: LGTM!

The new generateLib field is well-documented and correctly typed. The documentation clearly explains its purpose in controlling whether the generated code invokes main() or exports it as a library.

src/generator/server-code.ts (5)

55-55: LGTM!

The web transport correctly uses the new dynamic port resolution, which honors the PORT environment variable when --port is not specified.

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65-65: LGTM!

The StreamableHTTP transport correctly uses the new dynamic port resolution, consistent with the web transport.

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85-102: LGTM!

The conditional mainDeclaration block correctly implements the library generation mode:

• Omits cleanup and signal handlers when generateLib is true
• Includes proper shutdown handling and main invocation for standalone mode
• Aligns with the PR objective to allow main() to be imported and called from existing code

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182-182: LGTM!

The conditional export correctly implements the library generation mode. When generateLib is true, main() is exported for consumption by other code; otherwise, it remains a private function called by the startup code.

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186-186: LGTM!

The mainDeclaration insertion is correctly placed after the main() function definition, ensuring proper code structure in both library and standalone modes.