brain-of-reese/tests/unit/test_prompts.py

"""Unit: locked persona prompt builder (PLAN §6 verbatim + both modes).

Also covers the phase-31 ``<knowledge_base>`` section (the stored,
lite-generated KB outline): its own builder contract (empty → ``""``,
char budget + ``[…truncated…]`` marker, pathological budgets), its
placement between ``<relevance>`` and ``<tuning>`` in both modes, and
the byte-identical-when-absent convention (phase 15 precedent).
"""
from __future__ import annotations

import uuid

import pytest

from app.config import Settings
from app.models import Document
from app.rag.prompts import (
    PERSONA,
    TOOLS_SECTION,
    _base,
    build_deflect_prompt,
    build_high_prompt,
    build_kb_section,
    build_steering_section,
)
from app.rag.retriever import TRUNCATION_MARKER

#: A small multi-line outline standing in for the lite-generated one.
OVERVIEW = "- Homelab\n  - Kubernetes (k3s)\n- Deployments\n  - Borg backups"

#: The locked one-line intro of the ``<knowledge_base>`` section.
KB_INTRO = "The basic categories of everything in this knowledge base (generated at import time):"


def _doc(path: str, content: str, title: str) -> Document:
    return Document(
        id=uuid.uuid4(),
        source="Homelab",
        path=path,
        full_path=f"/tmp/{path}",
        title=title,
        content=content,
        content_hash="0" * 64,
    )


def test_persona_rules_present_verbatim() -> None:
    # Aligned to the owner's working-tree persona edits (PLAN §6 revision,
    # 2026-08-22): no "you've got this" tagline, no mandated deflection
    # opening. The honesty gate itself (rule 3) is unchanged.
    for fragment in (
        'You are "Brain of Reese" — the digital brain of Reese, a self-hoster and',
        "optimistic about the user's ability to do things",
        "Answer ONLY from the provided document context. Cite which document(s)",
        "you used, by path.",
        "Be concrete: names, versions, ports, hosts, schedules",
        'HONESTY GATE: if <relevance> is "LOW", you must NOT pretend to know',
        "Offer 2-3 alternative questions about things you DO have notes on.",
        "Never invent facts, hosts, or steps that are not in the context.",
        "Keep answers tight: short paragraphs, bullets where helpful.",
    ):
        assert fragment in PERSONA


def test_persona_owner_edits_are_preserved() -> None:
    """PLAN §6 revision (2026-08-22): the removed elements must stay out."""
    assert 'you\'ve got this' not in PERSONA  # tagline removed by the owner
    assert "Start your answer with a variant of" not in PERSONA  # no mandated opening
    assert "HONESTY GATE" in PERSONA  # the gate itself is intact


def test_high_prompt_carries_relevance_marker_and_full_documents() -> None:
    doc = _doc("kubernetes.md", "Talos Linux on three nodes.", "Kubernetes Homelab Cluster")
    prompt = build_high_prompt([doc])
    assert "<relevance>HIGH</relevance>" in prompt
    assert "DEFLECT_MODE" not in prompt
    assert "<documents>" in prompt and "</documents>" in prompt
    assert 'path="kubernetes.md"' in prompt
    assert "Talos Linux on three nodes." in prompt
    assert "HONESTY GATE" in prompt  # persona intact


def test_high_prompt_lists_multiple_documents_in_order() -> None:
    a = _doc("a.md", "CONTENT_A", "Title A")
    b = _doc("b.md", "CONTENT_B", "Title B")
    prompt = build_high_prompt([a, b])
    assert prompt.index("CONTENT_A") < prompt.index("CONTENT_B")
    assert 'title="Title B"' in prompt


def test_high_prompt_without_documents_stays_honest() -> None:
    prompt = build_high_prompt([])
    assert "<documents>" in prompt
    assert "do not invent specifics" in prompt


def test_low_prompt_has_deflect_mode_and_titles_only() -> None:
    titles = ["Kubernetes Homelab Cluster", "Backup Strategy"]
    prompt = build_deflect_prompt(titles)
    assert "<relevance>LOW</relevance>" in prompt
    assert "DEFLECT_MODE" in prompt  # marker the E2E mock keys on
    assert "- Kubernetes Homelab Cluster" in prompt
    assert "- Backup Strategy" in prompt


def test_low_prompt_never_contains_document_content() -> None:
    secret = "SECRET_DOCUMENT_CONTENT_12345"
    prompt = build_deflect_prompt(["Some Title"])
    assert secret not in prompt
    assert "<documents>" not in prompt
    assert "HONESTY GATE" in prompt  # the LOW rule is what the model must follow


def test_low_prompt_with_no_titles() -> None:
    assert "nothing close at all" in build_deflect_prompt([])


def test_zero_note_prompt_is_byte_identical_to_pre_steering() -> None:
    """Phase 15 contract: with no steering notes the prompt is exactly what
    it was before the <tuning> section existed. (Phase 37: the HIGH prompt
    additionally carries the ``<tools>`` section after the mode body — the
    fixtures account for it; the LOW prompt is untouched.)"""
    doc = _doc("kubernetes.md", "Talos Linux on three nodes.", "Kubernetes Homelab Cluster")
    block = (
        '<document source="Homelab" path="kubernetes.md" title="Kubernetes Homelab Cluster">\n'
        "Talos Linux on three nodes.\n"
        "</document>"
    )
    assert build_high_prompt([doc]) == (
        _base("HIGH") + "\n<documents>\n" + block + "\n</documents>" + "\n" + TOOLS_SECTION
    )
    assert build_deflect_prompt(["T1", "T2"]) == (
        _base("LOW")
        + "\nDEFLECT_MODE: retrieval was weak — the titles below are the closest "
        "your notes come to the question. They are titles only; do not pretend "
        "they answer it. Use them to propose 2-3 alternative questions.\n"
        + "- T1\n- T2"
    )
    assert "<tuning>" not in build_high_prompt([doc])
    assert "<tuning>" not in build_deflect_prompt([])


def test_relevance_placeholder_rejected_for_garbage() -> None:
    with pytest.raises(ValueError, match="HIGH or LOW"):
        _base("MEDIUM")


# ---------- <knowledge_base> section (phase 31) ----------


def test_kb_section_empty_when_no_overview() -> None:
    assert build_kb_section("") == ""
    assert build_kb_section("   \n\t ") == ""


def test_kb_section_format_intro_and_content() -> None:
    assert build_kb_section(OVERVIEW) == (
        f"<knowledge_base>\n{KB_INTRO}\n{OVERVIEW}\n</knowledge_base>"
    )


def test_kb_section_trims_overview_edges() -> None:
    assert build_kb_section(f"  {OVERVIEW}  \n") == build_kb_section(OVERVIEW)


def test_kb_section_fits_budget_exactly_no_marker() -> None:
    exact = f"<knowledge_base>\n{KB_INTRO}\n{OVERVIEW}\n</knowledge_base>"
    section = build_kb_section(OVERVIEW, max_chars=len(exact))
    assert TRUNCATION_MARKER not in section
    assert section == exact


def test_kb_section_over_budget_capped_with_marker() -> None:
    text = "- " + "x" * 500
    # The section frame alone is 121 chars, so the cap must clear it for
    # any outline prefix to fit (pathological budgets are tested below).
    cap = 200
    section = build_kb_section(text, max_chars=cap)
    assert len(section) <= cap  # the budget is never exceeded
    assert TRUNCATION_MARKER in section
    assert section.startswith(f"<knowledge_base>\n{KB_INTRO}\n-")
    assert section.endswith(f"{TRUNCATION_MARKER}\n</knowledge_base>")
    # The body is the kept prefix + the marker on its own line, and the
    # kept part must be a true prefix of the outline (longest-fitting).
    body = section.removeprefix(f"<knowledge_base>\n{KB_INTRO}\n").removesuffix(
        "\n</knowledge_base>"
    )
    kept, marker = body.rsplit("\n", 1)
    assert marker == TRUNCATION_MARKER
    assert kept.startswith("- ")
    assert text.startswith(kept), "the kept part must be a prefix of the outline"
    # And it is the longest such prefix: one more char would not fit.
    assert len(section) > cap - 2, "the cut must sit as close to the cap as possible"


def test_kb_section_default_budget_from_settings(monkeypatch: pytest.MonkeyPatch) -> None:
    from app.rag import prompts as prompts_mod

    monkeypatch.setattr(
        prompts_mod, "get_settings", lambda: Settings(_env_file=None)  # pyright: ignore[reportCallIssue]
    )
    text = "y" * 9_000  # > the 4 000-char default
    section = build_kb_section(text)
    assert TRUNCATION_MARKER in section
    assert len(section) <= 4_000


def test_kb_section_nonpositive_budget_is_empty() -> None:
    assert build_kb_section(OVERVIEW, max_chars=0) == ""
    assert build_kb_section(OVERVIEW, max_chars=-10) == ""


def test_kb_section_tiny_budget_never_exceeds_cap() -> None:
    # Pathological budget (steering precedent, phase 15): the section must
    # never exceed the cap — bare marker when it fits, no section at all
    # when even that doesn't.
    assert build_kb_section("a" * 500, max_chars=10) == ""  # marker (13) > 10
    fits_marker = build_kb_section("a" * 500, max_chars=len(TRUNCATION_MARKER))
    assert fits_marker == TRUNCATION_MARKER


# ---------- <knowledge_base> placement (both modes) ----------


def test_no_overview_prompt_is_byte_identical_to_pre_phase() -> None:
    """Phase 31 contract: with no KB overview (None, empty, or blank)
    every prompt is exactly what it was before the ``<knowledge_base>``
    section existed — with or without steering notes. (Phase 37: the HIGH
    prompt additionally carries the ``<tools>`` section after the mode
    body — the fixtures account for it; the LOW prompt is untouched.)"""
    doc = _doc("kubernetes.md", "Talos Linux on three nodes.", "Kubernetes Homelab Cluster")
    block = (
        '<document source="Homelab" path="kubernetes.md" title="Kubernetes Homelab Cluster">\n'
        "Talos Linux on three nodes.\n"
        "</document>"
    )
    docs_block = "\n<documents>\n" + block + "\n</documents>" + "\n" + TOOLS_SECTION
    high_plain = _base("HIGH") + docs_block
    high_steered = _base("HIGH") + "\n" + build_steering_section(["be concise"]) + docs_block
    low_plain = (
        _base("LOW")
        + "\nDEFLECT_MODE: retrieval was weak — the titles below are the closest "
        "your notes come to the question. They are titles only; do not pretend "
        "they answer it. Use them to propose 2-3 alternative questions.\n"
        + "- T1\n- T2"
    )
    low_steered = (
        _base("LOW")
        + "\n"
        + build_steering_section(["be concise"])
        + "\nDEFLECT_MODE: retrieval was weak — the titles below are the closest "
        "your notes come to the question. They are titles only; do not pretend "
        "they answer it. Use them to propose 2-3 alternative questions.\n"
        + "- T1\n- T2"
    )
    for kb in (None, "", "   \n\t "):
        assert build_high_prompt([doc], kb_overview=kb) == high_plain
        assert build_high_prompt([doc], notes=["be concise"], kb_overview=kb) == high_steered
        assert build_deflect_prompt(["T1", "T2"], kb_overview=kb) == low_plain
        assert build_deflect_prompt(
            ["T1", "T2"], notes=["be concise"], kb_overview=kb
        ) == low_steered
        assert "<knowledge_base>" not in build_high_prompt(
            [doc], notes=["be concise"], kb_overview=kb
        )
        assert "<knowledge_base>" not in build_deflect_prompt(
            ["T1"], notes=["be concise"], kb_overview=kb
        )


def test_high_prompt_kb_section_ordered_between_relevance_and_tuning() -> None:
    doc = _doc("kubernetes.md", "TALOS_DOC_CONTENT", "Kubernetes Homelab Cluster")
    prompt = build_high_prompt([doc], notes=["be concise"], kb_overview=OVERVIEW)
    i_rel = prompt.index("<relevance>HIGH</relevance>")
    i_kb_open = prompt.index("<knowledge_base>")
    i_kb_close = prompt.index("</knowledge_base>")
    i_tuning = prompt.index("<tuning>")
    i_docs = prompt.index("<documents>")
    assert i_rel < i_kb_open < i_kb_close < i_tuning < i_docs
    assert KB_INTRO in prompt
    assert OVERVIEW in prompt  # outline intact within the section
    assert "1. be concise" in prompt  # steering still there
    assert "TALOS_DOC_CONTENT" in prompt  # documents still full


def test_high_prompt_kb_section_without_steering() -> None:
    doc = _doc("kubernetes.md", "TALOS_DOC_CONTENT", "Kubernetes Homelab Cluster")
    prompt = build_high_prompt([doc], kb_overview=OVERVIEW)
    i_rel = prompt.index("<relevance>HIGH</relevance>")
    i_kb_close = prompt.index("</knowledge_base>")
    i_docs = prompt.index("<documents>")
    assert i_rel < i_kb_close < i_docs
    assert "<tuning>" not in prompt  # no notes → no steering section
    assert build_kb_section(OVERVIEW) in prompt


def test_deflect_prompt_kb_section_ordered_between_relevance_and_tuning() -> None:
    prompt = build_deflect_prompt(
        ["Title A", "Title B"], notes=["be concise"], kb_overview=OVERVIEW
    )
    i_rel = prompt.index("<relevance>LOW</relevance>")
    i_kb_open = prompt.index("<knowledge_base>")
    i_kb_close = prompt.index("</knowledge_base>")
    i_tuning = prompt.index("<tuning>")
    i_mode = prompt.index("DEFLECT_MODE")
    assert i_rel < i_kb_open < i_kb_close < i_tuning < i_mode
    assert KB_INTRO in prompt
    assert OVERVIEW in prompt
    assert "1. be concise" in prompt
    assert "- Title A" in prompt  # weak-hit titles still carried


def test_prompt_kb_section_over_settings_budget_capped_with_marker(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    """Prompt-level budget: an overview longer than
    ``kb_overview_max_chars`` is capped with the shared marker — in both
    modes."""
    from app.rag import prompts as prompts_mod

    monkeypatch.setattr(
        prompts_mod,
        "get_settings",
        # 200 > the 121-char section frame, so a prefix + marker can fit.
        lambda: Settings(_env_file=None, kb_overview_max_chars=200),  # pyright: ignore[reportCallIssue]
    )
    text = "- " + "z" * 500
    doc = _doc("kubernetes.md", "TALOS_DOC_CONTENT", "Kubernetes Homelab Cluster")
    for prompt in (
        build_high_prompt([doc], kb_overview=text),
        build_deflect_prompt(["Title A"], kb_overview=text),
    ):
        assert TRUNCATION_MARKER in prompt
        assert prompt.index("<knowledge_base>") < prompt.index(TRUNCATION_MARKER)
        # The capped section (open tag through close tag) fits the budget.
        section = prompt[prompt.index("<knowledge_base>") :]
        close = section.index("</knowledge_base>")
        section = section[: close + len("</knowledge_base>")]
        assert len(section) <= 200