fix: apply -q/non-TTY auto-quiet to a piped-stdin message (gh #93)

[dkedar7]

Issue

Closes #93.

-q/--quiet (and the non-TTY auto-quiet from #53) is documented to suppress the header, spinner, tool chatter, timing, and color and emit only the agent's reply. That contract held for a single-shot run (a MESSAGE arg or -f/--file) but not for the most idiomatic pipe form, echo "hi" | langstage-cli --demo -q: a stdin message is consumed by the interactive loop, which honored neither -q nor the stdout.isatty()==False auto-quiet — so it still emitted the ···· separator rules, the ❯ prompt row (with \x01\x02 bracketed-paste bytes), the Nms timing line, and a trailing Goodbye!. A script doing answer=$(echo "$q" | langstage-cli -q …) captured ~380 bytes of chrome around a 25-byte reply.

Root cause (two, both fixed)

1. Auto-quiet never fired for stdin. _QUIET keyed off (message or prompt_file or verify_agent) — a stdin-fed message is none of those, so the non-TTY auto-quiet was skipped.
2. The interactive loop applied no quiet gating at all — it always printed the separators, ❯ prompt, timing line and Goodbye!, regardless of _QUIET.

Fix

• The auto-quiet gate is now "stdout is not a TTY and the input is non-interactive" — a single-shot (MESSAGE/-f/--verify) or piped (non-TTY) stdin.
• The conversation loop honors _QUIET: it suppresses its ···· separators, the ❯ prompt (input() with no prompt string, so no glyph and no bracketed-paste bytes), the Nms timing line, and the Goodbye!, capping each reply with a single newline — byte-identical to the -q "msg" arg path.

Why quiet-the-loop, not reroute-to-single-shot

Piped stdin genuinely drives the loop in this CLI: it reads one line per turn via input() until EOF, so it can carry multiple messages and slash commands (printf 'hi\nbye\n' | … runs two turns; echo /config | … drives the command — the latter is exercised by an existing test). Rerouting a whole-stdin read to single-shot would collapse that capability. Quieting the loop keeps it while making every turn clean.

Before / after — echo "hi" | langstage-cli --demo -q

	bytes (stdout)	content
before	~380	···· rules, ❯ prompt, Nms timing, reply, Goodbye!
after	25	(demo agent) You said: hi — identical to the -q "hi" arg path

Tests

• test_piped_stdin_quiet_output_matches_the_message_arg_path — piped-stdin -q output is byte-for-byte equal to the -q MESSAGE-arg output; no Nms, ·, ❯, \x01\x02, or Goodbye.
• test_piped_stdin_auto_quiets_without_the_quiet_flag — the non-TTY auto-quiet also fires for a stdin message with no -q (the Single-shot output isn't scriptable: banner + spinner + ANSI all go to stdout (no --quiet / --output-format, no isatty gating) #53 goal).

Both fail on 0.6.22 and pass here. Full suite: 142 passed (140 baseline + 2). ruff check . and ruff format --check . both clean. A live TTY session (stdin is a tty, no -q) keeps _QUIET == False, so its header, separators, prompt, timing and farewell render unchanged.

🤖 Generated with Claude Code

https://claude.ai/code/session_011HWCfJii6gXd3XL3Gq3W8B