Fix log pattern end anchoring - #1338
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`CompilePattern` previously appended `\z` directly to each configured expression. With a top-level alternative such as `oom-kill|Out of memory`, the first branch could match an older line that was still in the buffer. Wrap the expression in a non-capturing group before adding the end anchor: - **Before:** `oom-kill|Out of memory\z` - **After:** `(?:oom-kill|Out of memory)\z` This makes every branch honor the documented end-of-buffer contract, lets last-line classification inspect a single parse tree, and adds regression coverage for stale matches.
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CompilePatternpreviously appended\zdirectly to each configured expression. Because|has lower precedence,oom-kill|Out of memory\zanchored only the second branch. The first branch could match a retained line again after every subsequent push until that line was overwritten, repeating temporary events and log-counter results.Group the expression before adding the end anchor:
oom-kill|Out of memory\z(?:oom-kill|Out of memory)\zThis makes every branch honor the end-of-buffer contract and removes the extra parse-tree comparison. Shipped configurations are unaffected because they already group their alternatives. Custom patterns with an unparenthesized top-level
|intentionally change behavior; use(?:oom-kill|Out of memory).*when either phrase should match anywhere before the end of the newest line./cc @DigitalVeer