docs: name the conflict watchpr will never report

README.md

@@ -88,13 +88,21 @@ gets a **new comment from someone other than the agent**, its **CI fails**
 transitions — CI `pending`→`success`, the agent's own comments and pushes — are
 ignored, and so is any condition the PR was already in at the baseline: a PR
 that is already conflicted or already failing when watching starts keeps being
-watched, and the baseline line says which conditions it is staying silent about.
+watched, and the baseline line — written to stderr, as a JSON record under
+`--json` — says which conditions it is staying silent about.
 
 Gitea reports `mergeable: false` both for a real conflict and while it
 recomputes the merge base after a push, so a conflict is only reported once the
-watch has seen a merge computation start — the PR was mergeable, or its head or
-base commit moved — and then only across two consecutive polls of an unchanged
-head and base.
+watch has seen a merge computation start (the PR was mergeable, or its head or
+base commit moved) **and** the non-mergeable polls have then run unbroken for
+two minutes. The debounce is a duration, not a poll count, because what it has
+to outlast is Gitea's recompute and `--interval` ranges from seconds to hours.
+
+One case is therefore never reported: a conflict introduced by the push
+immediately before the watch started, on a PR whose head and base never move
+again. Nothing in Gitea's payload separates that from a merge check still in
+flight, so watchpr stays silent about it for as long as it runs — the baseline
+line is how you see it.
 
 ```bash
 # Watch until something meaningful happens (default interval 60s)