hermes-agent/tests/tools/test_delegate_summary_budget.py

"""Tests for subagent summary budgeting (PR #9126).

delegate_task caps subagent summaries against the parent's remaining context
headroom (split across the batch) before they enter the parent's context, and
spills the full text to disk so nothing is lost. This guards the
compression/429 death spiral that batch fan-out could trigger by returning N
full summaries verbatim into the parent.
"""

import os
import tempfile

import pytest

import tools.delegate_tool as dt
from tools.delegate_tool_results import _MIN_SUMMARY_CHARS, _parent_summary_char_budget


class _FakeCompressor:
    def __init__(self, context_length, max_tokens):
        self.context_length = context_length
        self.max_tokens = max_tokens


class _FakeParent:
    def __init__(self, context_length, used_tokens, max_tokens, session_total=None):
        self.context_compressor = _FakeCompressor(context_length, max_tokens)
        # Current prompt size (last call) drives the budget; the cumulative session counter must not.
        self._last_turn_usage = {"prompt_tokens": used_tokens}
        self.session_prompt_tokens = session_total if session_total is not None else used_tokens


def test_small_summaries_pass_through_untouched():
    parent = _FakeParent(context_length=200_000, used_tokens=10_000, max_tokens=8_000)
    results = [
        {"task_index": 0, "summary": "short result A", "status": "completed"},
        {"task_index": 1, "summary": "short result B", "status": "completed"},
    ]
    dt._apply_summary_budget(results, parent)
    assert results[0]["summary"] == "short result A"
    assert "summary_truncated" not in results[0]
    assert "summary_truncated" not in results[1]


def test_batch_overflow_trimmed_and_spilled_losslessly(monkeypatch):
    # Isolate spill directory to a temp HERMES_HOME.
    with tempfile.TemporaryDirectory() as td:
        monkeypatch.setenv("HERMES_HOME", os.path.join(td, ".hermes"))
        # Distinct head + tail markers so we can prove the tail survives.
        big = "HEAD_MARKER\n" + ("X" * 50_000) + "\nTAIL_MARKER"
        # Parent nearly full (120k/131k) → tiny headroom → aggressive trim.
        parent = _FakeParent(context_length=131_000, used_tokens=120_000, max_tokens=8_000)
        results = [
            {"task_index": i, "summary": big, "status": "completed"} for i in range(5)
        ]
        dt._apply_summary_budget(results, parent)
        for r in results:
            assert r["summary_truncated"] is True
            assert len(r["summary"]) < len(big)
            # Head+tail window: both ends survive in-context.
            assert "HEAD_MARKER" in r["summary"]
            assert "TAIL_MARKER" in r["summary"]
            path = r.get("summary_full_path")
            assert path and os.path.exists(path)
            # The spill file holds the FULL original text — nothing is lost.
            with open(path, encoding="utf-8") as fh:
                assert fh.read() == big
            # The footer points the parent at the full version with an offset.
            assert "read_file" in r["summary"]
            assert "offset=" in r["summary"]
            # Spilled into the delegation cache (mounted into remote backends).
            assert os.path.join("cache", "delegation") in path


def test_empty_results_is_noop():
    # No summaries → nothing to do, must not raise.
    dt._apply_summary_budget([], _FakeParent(131_000, 1_000, 8_000))
    dt._apply_summary_budget(
        [{"task_index": 0, "status": "failed", "summary": None}],
        _FakeParent(131_000, 1_000, 8_000),
    )


def test_budget_uses_current_prompt_size_not_the_session_sum():
    """A long-lived parent has a session sum far past any window while its current prompt is small; the
    budget must follow the current prompt, otherwise every summary collapses to the floor."""
    long_lived = _FakeParent(context_length=200_000, used_tokens=30_000, max_tokens=8_000, session_total=25_000_000)
    fresh = _FakeParent(context_length=200_000, used_tokens=30_000, max_tokens=8_000)
    assert _parent_summary_char_budget(long_lived, 1) == _parent_summary_char_budget(fresh, 1)
    assert _parent_summary_char_budget(long_lived, 1) > _MIN_SUMMARY_CHARS


def test_unknown_parent_usage_means_static_ceiling_not_zero_context():
    """Independent-review witness: a parent with no usage yet was treated as 0 tokens used, so a 190K/200K
    prompt got a 384K-char summary budget instead of ~4K."""
    from types import SimpleNamespace
    from tools.delegate_tool_results import _parent_summary_char_budget
    parent = SimpleNamespace(context_compressor=SimpleNamespace(context_length=200_000, max_tokens=0),
                             _last_turn_usage=None)
    assert _parent_summary_char_budget(parent, 1) is None


def test_moa_fold_does_not_inflate_the_parents_prompt_size():
    """MoA folds advisor prompts into reported usage; the parent's context holds only the aggregator's."""
    from types import SimpleNamespace
    from tools.delegate_tool_results import _parent_summary_char_budget
    cc = SimpleNamespace(context_length=200_000, max_tokens=0)
    folded = SimpleNamespace(context_compressor=cc, _last_turn_usage={"prompt_tokens": 190_000}, _last_prompt_size_tokens=50_000)
    unfolded = SimpleNamespace(context_compressor=cc, _last_turn_usage={"prompt_tokens": 50_000})
    assert _parent_summary_char_budget(folded, 1) == _parent_summary_char_budget(unfolded, 1)