fix(init): stop specify init hanging on arrow-key pickers in agent harnesses

[lllakshit]

Description

Fixes #4152.

specify init can hang forever in select_with_arrows waiting for arrow-key input. --force only skips the merge confirmation, so an invocation like specify init --here --integration claude --force still reaches the script-type picker when stdin looks interactive.

That happens in AI agent harnesses: they often allocate a PTY (isatty() is true) but cannot send keypresses. The process then blocks with no timeout and no useful error.

This change:

1. Fails fast inside select_with_arrows when stdin is not a TTY, naming the flag that would supply the choice (--integration / --script) instead of hanging.
2. Adds --non-interactive so callers can suppress every picker even when stdin is a TTY. Unspecified selections use documented defaults (integration via SPECKIT_INTEGRATION_DEFAULT / Copilot; script type ps on Windows, sh otherwise). Merge into a non-empty directory still requires --force — there is no safe default for overwrite.
3. URL --extension installs follow the same rule: --non-interactive never calls typer.confirm. Without --trust-extension-urls the URL is denied; with it, the install proceeds without a prompt.

--force is unchanged: it still only means merge/overwrite, not "answer every prompt."

Workflows that already run multi-step processes non-interactively are not affected. This is specifically the specify init arrow-key picker path.

Testing

• Tested locally with specify init --help (--non-interactive is listed)
• Ran existing tests (focused pytest covering this change)
• Tested with a sample project

Focused pytest:

• picker / --non-interactive cases
• HTTPS --extension with TTY + --non-interactive (deny without --trust-extension-urls; install with it; typer.confirm fails if called)
• interactive Claude/Alquimia init tests

Local smoke test:

specify init <temp-dir> --non-interactive --ignore-agent-tools

completed without prompting, defaulted to Copilot / ps on Windows, and wrote .specify/init-options.json.

Test selection reasoning

Changed file	Affects	Test	Why
src/specify_cli/_console.py	specify init pickers	T1	Fail-fast lives in the shared selector
src/specify_cli/commands/init.py	specify init	T1	--non-interactive flag, prompt gating, URL allow_prompt
docs / README	docs only	—	User-facing flag documentation

Required tests

• T1: specify init --non-interactive — CLI init/scaffolding change; /speckit.specify is not affected (no command templates or scripts changed)

Manual test results

OS/Shell: Windows 10 / PowerShell

Command tested	Notes
specify init --help	--non-interactive listed
specify init <temp> --non-interactive --ignore-agent-tools	Pass — no hang, defaults to copilot + ps
pytest (non-interactive + URL extension cases)	Pass

AI Disclosure

• I did not use AI assistance for this contribution
• I did use AI assistance (describe below)

AI assistance was used to explore the TTY vs PTY hang and to draft tests. I reviewed the existing init prompt paths, chose fail-fast plus an explicit --non-interactive flag (without overloading --force), and ran the tests above.

[Copilot]

Pull request overview

Prevents specify init from hanging on arrow-key prompts in automated environments.

Changes:

• Adds non-TTY fail-fast behavior to the shared selector.
• Adds --non-interactive with safe defaults and prompt suppression.
• Adds tests and user documentation.

Show a summary per file

File	Description
src/specify_cli/_console.py	Adds non-TTY detection and actionable errors.
src/specify_cli/commands/init.py	Implements non-interactive initialization.
tests/test_console_imports.py	Tests selector fail-fast behavior.
tests/test_live_transient_windows.py	Adapts selector tests for TTY detection.
tests/integrations/test_cli.py	Tests non-interactive initialization scenarios.
README.md	Documents automation usage.
docs/quickstart.md	Explains non-interactive defaults.
docs/local-development.md	Clarifies script selection behavior.

Review details

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• Files reviewed: 8/8 changed files
• Comments generated: 1
• Review effort level: Balanced

[mnriem]

Please address Copilot feedback

[lllakshit]

Addressed the requested Copilot feedback in 1cef89a.

Added tests that run specify init --non-interactive with an HTTPS --extension while _stdin_is_interactive() is true, and fail if typer.confirm is called:

• without --trust-extension-urls, the URL is denied and typer.confirm is never invoked
• with --trust-extension-urls, install proceeds and typer.confirm is never invoked

Also covered the nonempty --here confirm path under --non-interactive the same way.

Please re-review.

[Copilot]

Review details

• Files reviewed: 8/8 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[mnriem]

Thank you!