From 73ff2ce20231b9390ed4daf5198cfb466272288f Mon Sep 17 00:00:00 2001
From: Tri Lam <tri@maydow.com>
Date: Mon, 1 Jun 2026 14:55:48 -0700
Subject: [PATCH] docs(patterns): correlation-window semantics rationale (#367)
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Three v1 detectors use three different correlation-window shapes:
pattern #7 (dataloader_hang) one-sided look-back, pattern #11
(checkpointer_hang) asymmetric back/forward legs, pattern #13
(silent_data_corruption) symmetric job window. The shapes were
chosen independently and the rationale lived only in code comments
and review threads.

Decision: (A) document the existing reality, do not converge.
Each shape matches a distinct physical event-ordering: strict
cause→symptom for #7, bidirectional log/threshold race for #11,
order-free job-scoped attribution for #13. A unified asymmetric
two-knob form (issue suggestion) would silently zero one leg for
#7 and would not apply to #13 at all; operators would tune knobs
that have no physical meaning for their pattern.

Adds a "Why this correlation shape" subsection to each pattern doc
and a "Correlation-window semantics" comparison table to
docs/patterns/README.md cross-linking the three rationales. No
code changes; no detector behavior changes.

Closes #367.

Signed-off-by: Tri Lam <tri@maydow.com>