1 files changed, 52 insertions, 1 deletions
diff --git a/wflib/res.py b/wflib/res.py
index e110daf..9add386 100644
--- a/wflib/res.py
+++ b/wflib/res.py
@@ -187,6 +187,9 @@ class Entry:
     env: dict = field(default_factory=dict)     # caller variables the user manager lacks (env_diff)
     by: dict = field(default_factory=dict)      # who started it (owner_by): name, task, batch, address
     lock: str = ""                              # '<key>@<main tree>': one queued/running job per lock (lock_for)
+    commit: str = ""                            # full sha the job tests (--commit / gate title): coalesce key
+    covers: list = field(default_factory=list)  # commits of superseded/covered same-lock entries, oldest queued first
+    superseded_by: str = ""                     # id of the queued entry on a descendant commit that replaced this one
     extra: dict = field(default_factory=dict, repr=False, compare=False)   # unknown keys of a newer version: kept on rewrite
 
     def eta(self) -> dt.datetime | None:
@@ -474,6 +477,54 @@ def lock_holder(led: Ledger, lock: str) -> Entry | None:
     return next((e for e in mine if e.state == "running"), None) or next(iter(_queue_of(mine)), None)
 
 
+COMMIT_TITLE_RE = re.compile(r"\b[0-9a-f]{7,40}\b")      # 'gate 1a2b3c4': the commit a locked job tests
+
+
+def coalesce(led: Ledger, new: Entry, is_ancestor) -> tuple[Entry | None, list[Entry]]:
+    """Same-lock queued entries vs a new queued entry on commit new.commit (ruling 2026-10-07: the queue coalesces,
+    one queued gate per lock and line of history). Returns (cover, gone): cover = a queued entry on the same or a
+    descendant commit (the new one is redundant, never queued); else gone = queued entries on ancestor commits
+    (the new one replaces them). is_ancestor(a, b) = a is an ancestor of b. Running entries are never touched."""
+    if not (new.lock and new.commit):
+        return None, []
+    same = [e for e in _queue_of(led.entries) if e is not new and e.lock == new.lock and e.commit]
+    for e in same:
+        if e.commit == new.commit or is_ancestor(new.commit, e.commit):
+            return e, []
+    return None, [e for e in same if is_ancestor(e.commit, new.commit)]
+
+
+def supersede(new: Entry, gone: list[Entry], now: dt.datetime) -> None:
+    """new replaces gone (queue order): they end 'superseded by new', new inherits their commits and the earliest
+    queue place (a coalesced gate never loses its turn)."""
+    for e in gone:
+        _finish(e, now, f"superseded by {new.id}")
+        e.superseded_by = new.id
+        new.covers = _uniq(new.covers + e.covers + [e.commit], new.commit)
+        if e.queued and (new.queued is None or e.queued < new.queued):
+            new.queued = e.queued
+
+
+def cover(e: Entry, commit: str, covers: list[str] = ()) -> None:
+    """e (queued, descendant commit) also stands for commit."""
+    e.covers = _uniq(e.covers + list(covers) + [commit], e.commit)
+
+
+def _uniq(commits: list[str], own: str) -> list[str]:
+    return [c for c in dict.fromkeys(commits) if c and c != own]
+
+
+def covers_text(e: Entry) -> str:
+    """' covers a1,b2 (red: culprit is one of them or <sha>; bisect …)' for a coalesced entry, else ''."""
+    if not e.covers:
+        return ""
+    out = f"; covers {','.join(c[:7] for c in e.covers)}"
+    if e.state == "done" and e.rc not in (0, None) and not e.superseded_by:
+        out += (f"; red: culprit is any commit in {e.covers[0][:7]}^..{e.commit[:7]} -> bisect (git bisect start "
+                f"{e.commit[:7]} {e.covers[0][:7]}^, rerun the job per step) or name that range in the P0 fix task")
+    return out
+
+
 def _queue_of(entries: list[Entry]) -> list[Entry]:
     return sorted((e for e in entries if e.state == "queued"), key=lambda e: (e.queued, int(e.id[2:])))
 
@@ -611,7 +662,7 @@ def done_line(e: Entry) -> str:
     minutes = round((e.ended - e.started).total_seconds() / 60) if e.ended and e.started else 0
     peak = fmt_gb(e.peak_gb) if e.peak_gb is not None else "?"
     why = f" ({e.why})" if e.why and e.why != "exited" else ""
-    return f"{e.id} done rc={rc_text(e.rc)} peak {peak} in {minutes} min{why}"
+    return f"{e.id} done rc={rc_text(e.rc)} peak {peak} in {minutes} min{why}{covers_text(e)}"
 
 
 JOURNAL_RESULT = re.compile(r"Failed with result '([^']+)'")