#!/usr/bin/env python3
"""``/plan`` — build the plan-mode prompt that turns the user's request into a
saved markdown implementation plan, with no execution.

``/plan`` used to be a bundled skill (``skills/software-development/plan``)
whose auto-generated slash command fell off the capped Telegram/Discord command
menus for most installs (skills are the only tier trimmed at the platform
caps, alphabetically — ``plan`` sat past the cutoff). It is now a first-class
built-in: this module builds ONE prompt that instructs the live agent to

  1. Stay in planning mode for the turn — read-only inspection is allowed,
     but no implementation, no mutating commands, no side effects.
  2. Write a concrete, bite-sized, TDD-shaped markdown plan under
     ``.hermes/plans/`` in the active workspace via ``write_file``.

There is no engine and no model-tool footprint: the agent does the work with
its existing toolset, so this works identically on local, Docker, and remote
terminal backends. Every surface (CLI ``/plan``, gateway ``/plan``, TUI
``/plan``) calls :func:`build_plan_prompt` and feeds the result to the agent
as a normal turn — same pattern as ``/learn`` and ``/init``, preserving
prompt-cache invariants (no system-prompt or history mutation).
"""

from __future__ import annotations

# The plan-mode ground rules + authoring craft, distilled from the retired
# bundled skill (v2.0.0, writing-craft adapted from obra/superpowers).
# Embedded in the prompt so the agent plans the way a maintainer would.
_PLAN_MODE_RULES = """\
For this turn, you are in PLAN MODE — planning only.

- Do not implement code.
- Do not edit project files except the plan markdown file itself.
- Do not run mutating terminal commands, commit, push, or perform external
  actions.
- You may inspect the repo or other context with read-only commands/tools
  when needed.
- Your deliverable is a markdown plan saved inside the active workspace under
  `.hermes/plans/YYYY-MM-DD_HHMMSS-<slug>.md` (create the directory if
  needed; Hermes file tools are backend-aware, so this relative path keeps
  the plan with the workspace on local, docker, ssh, modal, and daytona
  backends). If the runtime provides a specific target path, use that exact
  path instead.
"""

_PLAN_CRAFT = """\
Write the plan for an implementer with zero context for the codebase and
questionable taste. A good plan makes implementation obvious — if someone has
to guess, the plan is incomplete.

Structure (include the sections that are relevant):
- Goal — one sentence.
- Current context / assumptions.
- Architecture / proposed approach — 2-3 sentences.
- Step-by-step tasks. Each task is bite-sized (2-5 minutes of focused work),
  names exact file paths (`src/models/user.py`, not "the model file"),
  includes complete copy-pasteable code where code is needed, and exact
  commands with expected output for verification.
- Tests / validation — for code tasks, follow the TDD cycle per task: write
  the failing test, run it to verify failure, implement minimally, run to
  verify pass, commit.
- Risks, tradeoffs, and open questions.

Principles: DRY, YAGNI, TDD, frequent commits. Avoid vague tasks ("add
authentication"), incomplete code ("add validation here"), and unverifiable
steps ("test it works" — instead: the exact command and its expected output).

Interaction style:
- If the request is clear enough, write the plan directly.
- If it is genuinely underspecified, ask a brief clarifying question instead
  of guessing.
- After saving the plan, reply briefly with what you planned and the saved
  path, and offer to execute it (e.g. via subagent-driven development) —
  but do not start executing in this turn.
"""


def build_plan_prompt(task: str = "") -> str:
    """Build the plan-mode prompt for the live agent.

    Args:
        task: What to plan. Empty → infer the task from the current
            conversation context (mirrors the retired skill's behavior and
            issue #36821's "plan from context" expectation).
    """
    task = (task or "").strip()
    if task:
        task_block = f"Task to plan:\n{task}\n"
    else:
        task_block = (
            "No explicit task was given with /plan — infer the task from the "
            "current conversation context (the thing we have been discussing "
            "or working toward). If the conversation does not imply a task, "
            "ask a brief clarifying question.\n"
        )
    return (
        "[/plan — plan mode]\n\n"
        + _PLAN_MODE_RULES
        + "\n"
        + task_block
        + "\n"
        + _PLAN_CRAFT
    )