diff --git a/references/briefs.md b/references/briefs.md
index a3664c0..1181190 100644
--- a/references/briefs.md
+++ b/references/briefs.md
@@ -335,11 +335,12 @@ pid with no match is exit 98. `tools/wait-on.sh pid <pid> [<log>]` is only for a
 process with no completion evidence; it prints `GONE (no completion evidence)`
 and its exit 0 means "gone", not "succeeded". `tools/wait-on.sh file <path>` is
 for an output file written last. The regex is an ERE; an invalid one is exit 3.
-Use a fresh log path per job. If a log path is reused (Unity `-logFile`, a
-re-run script), record where it ended at launch and pass it, so a stale done
-line from the earlier job does not count: `WAIT_FROM=$(wc -c < <log> 2>/dev/null
-|| echo 0)` captured before the launch, then `WAIT_FROM=<n> tools/wait-on.sh log
-<log> <regex>`. Same contract as the ygg-verify wait: pass a Bash tool `timeout`
+Exit 3 means the regex is invalid: fix it, never retry it unchanged.
+Every job gets a fresh log path (put the job's own unique name or a timestamp in
+it; for Unity, a new `-logFile` path per launch), and a waiter is never pointed
+at a log a previous job wrote: a reused log's old done line reads as success at
+once, and an offset cannot fix that because truncating writers (`>`, Unity
+`-logFile`) rewrite below it. Same contract as the ygg-verify wait: pass a Bash tool `timeout`
 of at least 280000 ms, it blocks at most 270 s, exit 0 is done with a bounded
 log tail, `RUNNING <n>s` (exit 99) means call it again, exit 98 means the thing
 is gone with no completion evidence. Bare `true`, `echo waiting` and `sleep`