PR #16352: fix(error_classifier): avoid large-context false overflow heuristics

• Repository: NousResearch/hermes-agent
• Author: JayGwod
• State: open | merged: False
• Link: https://github.com/NousResearch/hermes-agent/pull/16352

Description (problem / solution / changelog)

Summary

Fixes a large-context false-positive in agent.error_classifier: generic HTTP 400 responses and server disconnects should not be classified as context_overflow solely because a 1M-context session has many messages.

The previous heuristic used absolute fallbacks:

approx_tokens > 80000 or num_messages > 80
approx_tokens > 120000 or num_messages > 200

Those thresholds are useful proxies for smaller context windows, but they are too aggressive for explicitly large windows. A 1M-context session can have 432 messages and ~74K estimated tokens while still being far below the real budget.

This patch keeps the relative pressure checks for all models, but gates the absolute token/message-count fallbacks to smaller context windows (<= 256000).

Behavior covered

• Generic 400 with approx_tokens=74320, context_length=1_000_000, num_messages=432 is now format_error, not context_overflow.
• Server disconnect with the same low-pressure 1M context shape is now timeout, not context_overflow.
• Existing smaller-window behavior remains covered by existing tests.

Test plan

RED before fix:

/home/ubuntu/.hermes/hermes-agent/venv/bin/python -m pytest \
  tests/agent/test_error_classifier.py::TestClassifyApiError::test_400_generic_many_messages_below_large_context_pressure_is_format_error \
  tests/agent/test_error_classifier.py::TestClassifyApiError::test_disconnect_many_messages_below_large_context_pressure_is_timeout \
  -v -o 'addopts='

Both tests failed with FailoverReason.context_overflow.

GREEN after fix:

/home/ubuntu/.hermes/hermes-agent/venv/bin/python -m pytest tests/agent/test_error_classifier.py -q -o 'addopts='
/home/ubuntu/.hermes/hermes-agent/venv/bin/python -m py_compile agent/error_classifier.py tests/agent/test_error_classifier.py
git diff --check

Result:

120 passed

Manual reproduction after fix:

FakeHTTP400 FailoverReason.format_error False False
Exception FailoverReason.timeout True False

Fixes #16351

Related: #14499, #14858, #14953, #15844, #6751

Changed files

• agent/error_classifier.py (modified, +12/-2)
• tests/agent/test_error_classifier.py (modified, +32/-0)

PR #16380: fix(error_classifier): gate absolute msg/token heuristics to small context windows

• Repository: NousResearch/hermes-agent
• Author: Sanjays2402
• State: open | merged: False
• Link: https://github.com/NousResearch/hermes-agent/pull/16380

Description (problem / solution / changelog)

Closes #16351.

Problem

agent/error_classifier.py flagged non-context errors as context_overflow in long-context (1M) Codex/GPT-5.x sessions, purely because num_messages > 80 (generic 400) or num_messages > 200 (disconnect) — even when approx_tokens was a fraction of the actual budget.

Repro from the issue:

classify_api_error(
    FakeHTTP400(),
    provider="openai-codex",
    model="gpt-5.5",
    approx_tokens=74320,
    context_length=1_000_000,
    num_messages=432,
)
# Before: FailoverReason.context_overflow (retryable=True, should_compress=True)
# After:  FailoverReason.format_error      (retryable=False, should_compress=False)

That sent format errors into the compression/probe-down path, causing unnecessary compaction and stale handoff pollution on 1M sessions.

Fix

Apply exactly the gate suggested in the issue body: scope absolute token/message-count fallbacks to context_length <= 256000. Relative pressure thresholds (> 0.6 for disconnect, > 0.4 for generic 400) still fire on any context size.

# server disconnect path
is_large = approx_tokens > context_length * 0.6 or (
    context_length <= 256000 and (approx_tokens > 120000 or num_messages > 200)
)

# generic 400 path
is_large = approx_tokens > context_length * 0.4 or (
    context_length <= 256000 and (approx_tokens > 80000 or num_messages > 80)
)

Existing behavior for ~128K/200K context windows is unchanged.

Tests

tests/agent/test_error_classifier.py — 4 new tests covering the 1M-context regime:

• test_400_generic_1m_context_high_message_count_not_overflow — exact repro from issue (74K tokens, 432 msgs, 1M ctx) → format_error.
• test_400_generic_1m_context_relative_pressure_still_overflow — 500K tokens / 1M ctx still → context_overflow.
• test_disconnect_1m_context_high_message_count_is_timeout — 150K tokens, 300 msgs, 1M ctx → timeout.
• test_disconnect_1m_context_relative_pressure_still_overflow — 700K tokens / 1M ctx still → context_overflow.

pytest tests/agent/test_error_classifier.py -q
122 passed (118 pre-existing + 4 new)

Changed files

• agent/error_classifier.py (modified, +6/-2)
• tests/agent/test_error_classifier.py (modified, +62/-0)