Reviewer regression (reproduced): _STATE_DB_DISPLAY_ROW_BACKSTOP (newest-50k SQL cap) was applied UNCONDITIONALLY to the GET /api/session display path's state.db read. But merge_session_messages_append_only needs the rows at/around the session's truncation_boundary (the preserved prefix) to reconcile correctly. A newest-N-only cap drops those boundary rows for a >N-row session and corrupts the merge (silently losing the preserved prefix), and also prevents older-page (msg_before) requests from ever reaching them. So a pathological-but-real >50k- row compressed session got a corrupted merge / unreachable older history rather than a clean bound. Fix: gate the backstop on the SAME conditions _state_db_since_timestamp_for_limited_display uses to decide a read is boundary-free — not msg_before paging, and no truncation_watermark / truncation_boundary. Those cases stay on the full (uncapped) read; the backstop is now a defensive net for the common uncompressed initial-tail path only. Extracted into _state_db_backstop_limit_for_display for direct test coverage. The get_state_db_session_messages(limit=) signature + newest-rows subquery are unchanged — only the display-path APPLICATION of the cap is gated. Test: tests/test_state_db_backstop_boundary_gate.py — backstop applies with no boundary prefix; SKIPPED when truncation_boundary / truncation_watermark set or msg_before paging; empty-string markers treated as unset (matching the existing helper). Existing backstop + reconciliation suites (53 tests) unchanged. Model Used: builtin:zai-coding-plan/GLM-5.2 (ZCode agent).
69 lines
3.3 KiB
Python
69 lines
3.3 KiB
Python
"""Tests: the display-path state.db row backstop is GATED on the absence of a
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truncation_boundary prefix.
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Regression (reviewer): ``_STATE_DB_DISPLAY_ROW_BACKSTOP`` was applied
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unconditionally to the ``GET /api/session`` display path's state.db read. But
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``merge_session_messages_append_only`` needs the rows at/around the session's
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``truncation_boundary`` (the preserved prefix) to reconcile correctly. A
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newest-N-only SQL cap drops those boundary rows for a >N-row session and
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corrupts the merge (silently losing the preserved prefix), and also prevents
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older-page (``msg_before``) requests from reaching them.
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The fix gates the backstop via ``_state_db_backstop_limit_for_display`` on the
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same conditions ``_state_db_since_timestamp_for_limited_display`` uses to decide
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a read is boundary-free: NOT ``msg_before`` paging, and NO
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``truncation_watermark`` / ``truncation_boundary``. Those cases stay on the full
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(uncapped) read. The helper is the unit under test (driving the full handler
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end-to-end is brittle across its many dependencies).
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"""
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from __future__ import annotations
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from api.routes import _STATE_DB_DISPLAY_ROW_BACKSTOP, _state_db_backstop_limit_for_display
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class _StubSession:
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"""Minimal object exposing the boundary attributes the gate checks."""
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def __init__(self, **attrs):
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self.truncation_watermark = attrs.get("truncation_watermark", None)
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self.truncation_boundary = attrs.get("truncation_boundary", None)
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def test_backstop_applied_when_no_boundary_prefix():
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"""An uncompressed, initial-tail session (no truncation_watermark /
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truncation_boundary, no msg_before) gets the defensive row backstop."""
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assert _state_db_backstop_limit_for_display(_StubSession(), msg_before=None) == _STATE_DB_DISPLAY_ROW_BACKSTOP
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def test_backstop_skipped_when_truncation_boundary_set():
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"""Regression: a compressed session (truncation_boundary set) needs its
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preserved-prefix rows for the merge, so the backstop must NOT cap the read."""
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stub = _StubSession(truncation_boundary="some-boundary-marker")
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assert _state_db_backstop_limit_for_display(stub, msg_before=None) is None
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def test_backstop_skipped_when_truncation_watermark_set():
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"""Same gate for truncation_watermark — the merge needs the prefix rows."""
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stub = _StubSession(truncation_watermark=12345)
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assert _state_db_backstop_limit_for_display(stub, msg_before=None) is None
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def test_backstop_skipped_when_msg_before_paging():
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"""Older-page (msg_before) requests need to reach the boundary rows, so the
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backstop must not cap them either."""
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stub = _StubSession()
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assert _state_db_backstop_limit_for_display(stub, msg_before=500) is None
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def test_backstop_boundary_check_handles_empty_string_as_unset_or_set():
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"""The gate treats empty-string boundary markers as 'not set' (matches the
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existing since_timestamp helper's `in (None, "")` check). A real marker
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(non-empty) triggers the skip."""
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# Empty string = treated as unset → backstop applies.
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assert _state_db_backstop_limit_for_display(
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_StubSession(truncation_boundary=""), msg_before=None
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) == _STATE_DB_DISPLAY_ROW_BACKSTOP
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# Non-empty string = boundary present → backstop skipped.
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assert _state_db_backstop_limit_for_display(
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_StubSession(truncation_watermark="wm"), msg_before=None
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) is None
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