feat: add interactive recipient composer

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a03397-4d51-7fd1-8ff2-946eb22ea2bc

src/tamq/composer.py

@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+import os
+import re
+import sys
+import termios
+import tty
+from collections.abc import Sequence
+
+
+class ComposerError(RuntimeError):
+    pass
+
+
+def recipient_order(
+    current_repo: str,
+    latest_counterparty: str | None,
+    session_repos: Sequence[str],
+) -> tuple[str, ...]:
+    """Put the latest sender first, then the remaining peer repositories."""
+    ordered: list[str] = []
+    for repo in ([latest_counterparty] if latest_counterparty else []):
+        if (
+            repo != current_repo
+            and repo not in ordered
+            and re.fullmatch(r"[A-Za-z0-9][A-Za-z0-9._-]*", repo) is not None
+        ):
+            ordered.append(repo)
+    for repo in session_repos:
+        if (
+            repo != current_repo
+            and repo not in ordered
+            and re.fullmatch(r"[A-Za-z0-9][A-Za-z0-9._-]*", repo) is not None
+        ):
+            ordered.append(repo)
+    return tuple(ordered)
+
+
+def _remove_last_character(value: bytearray) -> None:
+    if not value:
+        return
+    removed = value.pop()
+    if removed & 0xC0 == 0x80:
+        while value and value[-1] & 0xC0 == 0x80:
+            value.pop()
+        if value and value[-1] & 0xC0 == 0xC0:
+            value.pop()
+
+
+def compose_message(
+    recipients: Sequence[str],
+    *,
+    input_fd: int | None = None,
+    output_fd: int | None = None,
+) -> tuple[str, str] | None:
+    """Read one literal terminal line while Tab cycles the visible recipient."""
+    if not recipients:
+        raise ComposerError("no recipient is available")
+    try:
+        source = sys.stdin.fileno() if input_fd is None else input_fd
+        destination = sys.stderr.fileno() if output_fd is None else output_fd
+    except (AttributeError, OSError) as exc:
+        raise ComposerError("interactive composition requires a terminal") from exc
+    if not os.isatty(source) or not os.isatty(destination):
+        raise ComposerError("interactive composition requires a terminal")
+
+    saved = termios.tcgetattr(source)
+    draft = bytearray()
+    recipient_index = 0
+    escape_state = 0
+
+    def write(value: bytes) -> None:
+        offset = 0
+        while offset < len(value):
+            offset += os.write(destination, value[offset:])
+
+    def render() -> None:
+        prompt = f"@{recipients[recipient_index]}: ".encode("utf-8")
+        write(b"\r\x1b[2K" + prompt + draft)
+
+    try:
+        tty.setraw(source)
+        render()
+        while True:
+            value = os.read(source, 1)
+            if not value:
+                write(b"\r\n")
+                return None
+            byte = value[0]
+            if escape_state == 1:
+                escape_state = 2 if byte in (ord("["), ord("O")) else 0
+                continue
+            if escape_state == 2:
+                if 0x40 <= byte <= 0x7E:
+                    escape_state = 0
+                continue
+            if byte == 0x1B:
+                escape_state = 1
+            elif byte == 0x09:
+                recipient_index = (recipient_index + 1) % len(recipients)
+                render()
+            elif byte in (0x0A, 0x0D):
+                try:
+                    body = draft.decode("utf-8")
+                except UnicodeDecodeError:
+                    write(b"\a")
+                    continue
+                if not body.strip():
+                    write(b"\a")
+                    continue
+                write(b"\r\n")
+                return recipients[recipient_index], body
+            elif byte == 0x03:
+                write(b"^C\r\n")
+                return None
+            elif byte == 0x04 and not draft:
+                write(b"\r\n")
+                return None
+            elif byte in (0x08, 0x7F):
+                _remove_last_character(draft)
+                render()
+            elif byte == 0x15:
+                draft.clear()
+                render()
+            elif byte >= 0x20:
+                draft.extend(value)
+                write(value)
+            else:
+                write(b"\a")
+    finally:
+        termios.tcsetattr(source, termios.TCSADRAIN, saved)