feat: headless_prompt method on AgentProvider + --prompt arg

bot_bottle/cli/start.py

@@ -21,7 +21,7 @@ import tempfile
 from pathlib import Path
 from typing import Callable
 
-from ..agent_provider import runtime_for
+from ..agent_provider import get_provider, runtime_for
 from ..backend import (
     Bottle,
     BottleSpec,
@@ -83,6 +83,11 @@ def cmd_start(argv: list[str]) -> int:
         default=None,
         help="bottle color, one of the 16 ANSI color names (--headless default: none)",
     )
+    parser.add_argument(
+        "--prompt",
+        default=None,
+        help="initial task prompt delivered to the agent (required with --headless)",
+    )
     parser.add_argument(
         "name",
         nargs="?",
@@ -169,6 +174,13 @@ def _start_headless(
         die("--headless requires an agent name: ./cli.py start <agent> --headless")
     manifest.require_agent(agent_name)  # raises ManifestError if unknown
 
+    prompt = args.prompt
+    if not prompt:
+        die(
+            "--headless requires --prompt: "
+            "./cli.py start <agent> --headless --prompt 'Do the thing'"
+        )
+
     if args.bottle:
         bottle_names: tuple[str, ...] = tuple(args.bottle)
     else:
@@ -192,7 +204,11 @@ def _start_headless(
         bottle_names=bottle_names,
     )
     return _launch_bottle(
-        spec, dry_run=dry_run, backend_name=backend_name, assume_yes=True
+        spec,
+        dry_run=dry_run,
+        backend_name=backend_name,
+        assume_yes=True,
+        headless_prompt_text=prompt,
     )
 
 
@@ -480,13 +496,18 @@ def _launch_bottle(
     dry_run: bool,
     backend_name: str | None = None,
     assume_yes: bool = False,
+    headless_prompt_text: str = "",
 ) -> int:
     """Shared launch core for `start` and `resume`. Builds the plan,
     prints / dry-runs / prompts as appropriate, brings the bottle up,
     attaches claude, and prints the resume hint on session end.
 
     `assume_yes` skips the interactive y/N confirmation (headless /
-    orchestrator launches), where there is no human at the prompt."""
+    orchestrator launches), where there is no human at the prompt.
+
+    `headless_prompt_text` is passed to the provider's `headless_prompt`
+    method and the resulting args are appended to startup_args so the
+    agent receives the initial task without interactive input."""
     stage_dir = Path(tempfile.mkdtemp(prefix="bot-bottle-stage."))
     identity = ""
     try:
@@ -504,10 +525,17 @@ def _launch_bottle(
         backend = get_bottle_backend(backend_name)
         with backend.launch(plan) as bottle:
             agent_provider_template = getattr(plan, "agent_provider_template", "claude")
+            extra_args: tuple[str, ...] = ()
+            if headless_prompt_text:
+                extra_args = tuple(
+                    get_provider(agent_provider_template).headless_prompt(
+                        headless_prompt_text
+                    )
+                )
             exit_code = attach_agent(
                 bottle,
                 agent_provider_template=agent_provider_template,
-                startup_args=plan.agent_provision.startup_args,
+                startup_args=plan.agent_provision.startup_args + extra_args,
             )
             info(
                 f"session ended (exit {exit_code}); "