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

"""Prompt-lock pin (phase 112, task 03 — owner decision iii, 2026-09-14).

The persona + HONESTY GATE text is **locked verbatim** (PLAN §6): it
changes through the plan, never in code. This module byte-pins the
locked prompt constants against their pre-phase-112 anchor values —
sha256 + exact prefix/suffix + total length, so *any* byte change
(option (i)'s copy tightening, option (ii)'s plan amendment, or an
accidental edit) fails loudly until the anchors are re-cut as part of
the same plan revision. ``tests.unit.test_prompts`` pins the
assembled-prompt structure and the behavioral contracts on top of
these constants; this file pins the constants themselves.
"""
from __future__ import annotations

import hashlib

from app.rag.prompts import (
    PERSONA,
    SUGGEST_INTRO,
    TOOLS_SECTION,
    _base,
    build_deflect_prompt,
)


def _sha256(text: str) -> str:
    return hashlib.sha256(text.encode("utf-8")).hexdigest()


# ---------- PERSONA (the locked base of BOTH the HIGH and LOW prompts) ----------

#: Pre-phase-112 anchors for ``PERSONA`` (the ``{relevance}`` placeholder
#: and the line wrapping included).
PERSONA_SHA256 = "e31792a73e64c53853097e0f7b6df8b96c5f2d05c286944c3edba16dde7777fe"
PERSONA_LEN = 706
PERSONA_PREFIX = (
    'You are "Brain of Reese" — the digital brain of Reese, a self-hoster and\n'
    "homelab tinkerer. Personality: chippy, upbeat, warm, and genuinely\n"
    "optimistic about the user's ability to do things.\n"
    "\n"
    "Rules:\n"
)
PERSONA_SUFFIX = (
    "4. Never invent facts, hosts, or steps that are not in the context.\n"
    "5. Keep answers tight: short paragraphs, bullets where helpful.\n"
    "\n"
    "<relevance>{relevance}</relevance>"
)


def test_persona_byte_locked() -> None:
    """Any byte change to the locked persona (opening, any rule line, the
    ``<relevance>`` placeholder) fails on the sha256; the prefix/suffix
    anchors name the damaged region for the diff."""
    assert len(PERSONA) == PERSONA_LEN
    assert _sha256(PERSONA) == PERSONA_SHA256
    assert PERSONA.startswith(PERSONA_PREFIX)
    assert PERSONA.endswith(PERSONA_SUFFIX)


def test_high_and_low_bases_byte_locked() -> None:
    """``_base`` only substitutes ``{relevance}`` — the per-mode base
    lengths pin the substitution against a moved or re-spelled
    placeholder in the locked text."""
    assert len(_base("HIGH")) == 699  # PERSONA_LEN - 11 + 4
    assert len(_base("LOW")) == 698  # PERSONA_LEN - 11 + 3


# ---------- TOOLS_SECTION (the HIGH prompt's locked ``<tools>`` copy) ----------

#: Anchors for ``TOOLS_SECTION`` — pre-phase-112 values, RE-CUT for
#: phase 118 (task 04, A6, owner directive 2026-09-15): the ``read``
#: clause was rewritten for the summary-seed mode (the ``<documents>``
#: section holds SUMMARIES — ``read`` adds the full text; only an
#: already-read document is refused). Only that clause moved — the
#: prefix (the ``ls``-clause opening) and the suffix (the
#: discipline-rules ending) survived byte-identical, so they are the
#: same anchors as pre-phase-118.
TOOLS_SECTION_SHA256 = "87ee80faf0170da6ab1de518177313def6460785613fa074312a2a5f9f071750"
TOOLS_SECTION_LEN = 2465
TOOLS_SECTION_PREFIX = (
    "<tools>\n"
    "You may extend your context with three tools. `ls` lists the "
    "knowledge base as a tree, one level at a time: "
)
TOOLS_SECTION_SUFFIX = (
    "Never repeat a call that was refused or already succeeded — the refusal "
    "already told you the correct form. Answer as soon as you have what "
    "you need.\n</tools>"
)


def test_tools_section_byte_locked() -> None:
    """The ``<tools>`` teaching is LOCKED verbatim too (the E2E mock keys
    on the ``<tools>`` marker's presence; the wording is the owner's):
    sha256 + exact prefix/suffix + total length."""
    assert len(TOOLS_SECTION) == TOOLS_SECTION_LEN
    assert _sha256(TOOLS_SECTION) == TOOLS_SECTION_SHA256
    assert TOOLS_SECTION.startswith(TOOLS_SECTION_PREFIX)
    assert TOOLS_SECTION.endswith(TOOLS_SECTION_SUFFIX)


# ---------- the LOW prompt's locked DEFLECT_MODE body ----------

#: The ``DEFLECT_MODE`` body exactly as it was pre-phase-112 (the
#: phase-71 plain-text line included) — inline in
#: :func:`app.rag.prompts.build_deflect_prompt`, so it is pinned through
#: the built prompt rather than a module constant.
LOW_BODY_SHA256 = "c9868cfccdd0ff79d7c1de5df5f6dea0182d3726ca912c9ef609ab54b563a0a4"
LOW_BODY_LEN = 259
LOW_BODY = (
    "DEFLECT_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"
    "Reply in plain text only — you have no tools in this mode."
)


def test_deflect_body_byte_locked() -> None:
    """The LOW build = locked base + exactly the locked DEFLECT_MODE body
    + the weak-hit title list — byte for byte (the mock keys on the
    ``DEFLECT_MODE`` marker's presence; the body wording is locked)."""
    assert len(LOW_BODY) == LOW_BODY_LEN
    assert _sha256(LOW_BODY) == LOW_BODY_SHA256
    assert build_deflect_prompt(["T1", "T2"]) == _base("LOW") + "\n" + LOW_BODY + "\n- T1\n- T2"
    prompt = build_deflect_prompt(["T1", "T2"])
    assert prompt.count(LOW_BODY) == 1
    assert prompt.index("DEFLECT_MODE") < prompt.index(
        "Reply in plain text only"
    )  # the marker precedes the plain-text line


#: The full LOW prompt build on the canonical fixture titles — sha-pinned
#: (phase 118, task 03): the deflection path is UNTOUCHED by the
#: summary-seed re-revision (LOCKED A8) — the same inputs must produce
#: the pre-phase bytes, so this anchor is a pre-phase-118 value.
LOW_PROMPT_SHA256 = "726eddb4eb3bcc26c840011f6f8635d6af55aa09d4d064bbb9e256caa9665837"
LOW_PROMPT_LEN = 968


def test_low_prompt_build_byte_identical_to_pre_phase() -> None:
    """Phase 118 contract: the LOW prompt output is byte-identical to
    pre-phase for identical inputs — the summary seeding (and the new
    ``SUGGEST_INTRO`` line) never leaks into the deflection path."""
    prompt = build_deflect_prompt(["T1", "T2"])
    assert len(prompt) == LOW_PROMPT_LEN
    assert _sha256(prompt) == LOW_PROMPT_SHA256
    assert "SUGGEST_INTRO" not in prompt and "<documents>" not in prompt


# ---------- SUGGEST_INTRO (phase 118, task 03 — the start-here framing) ----------

#: Phase-118 anchors for ``SUGGEST_INTRO`` — the ``<documents>``
#: section's intro line (the owner's "start here if these summaries seem
#: right to you" framing, TODO L3). The E2E mock's ``_document_block``
#: parser is regex-based over the block markup (which stays byte-stable
#: around the intro), so this constant is a prompt-copy lock, pinned the
#: way ``TOOLS_SECTION`` is: sha256 + prefix + total length.
SUGGEST_INTRO_SHA256 = "7b14d2dedc6ebc4e440d32dd1edb979a7461c94034b9541c9f37b9042f394d3a"
SUGGEST_INTRO_LEN = 323
SUGGEST_INTRO_PREFIX = (
    "The blocks below are the summaries of the top-ranked documents for "
    "your question — start here if one seems right to you: "
)


def test_suggest_intro_byte_locked() -> None:
    """The start-here framing is LOCKED copy (phase 118): sha256 + exact
    prefix + total length; the three contracts it must carry (summaries
    are the starting points; ``read`` adds the full text, which is NOT
    in the prompt until read; cite by path) are pinned as substrings."""
    assert len(SUGGEST_INTRO) == SUGGEST_INTRO_LEN
    assert _sha256(SUGGEST_INTRO) == SUGGEST_INTRO_SHA256
    assert SUGGEST_INTRO.startswith(SUGGEST_INTRO_PREFIX)
    assert "call `read`" in SUGGEST_INTRO
    assert "combined `source/path`" in SUGGEST_INTRO
    assert "its full text is not in the prompt until you read it" in SUGGEST_INTRO
    assert "Cite the document(s) you used, by path." in SUGGEST_INTRO