From 7b522de9e7931652840a0faab8b18509d9e917b8 Mon Sep 17 00:00:00 2001
From: Ihor Rusyn <0kaba0@gmail.com>
Date: Sun, 19 Jul 2026 11:40:31 +0200
Subject: [PATCH] debug: log every loadOrInit stat outcome, not just the
 ErrNotExist branch (#644)
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Live evidence on latest (post-#655): the NextUID regression still reproduces,
with only ONE createFresh call observed for the affected path (from
yarilo-imap), none from yarilo-lmtp — disproving the "two processes both
discover a missing file simultaneously" theory. yarilo-lmtp had already used
the same folder successfully through uid=19 before yarilo-imap's os.Stat on
the identical path returned ErrNotExist ~1.4s later.

loadOrInit now logs the stat outcome (exists/size/mod_time, or the literal
error) on every call, not just when it's about to call createFresh — so a
live repro can see the full stat-outcome history for a given index_path
across processes instead of inferring it from the presence/absence of a
createFresh WARN on one side only.

Purely additive logging — no behavior change. go test ./... green.
---
 helm/Chart.yaml                       |  4 ++--
 internal/storage/index/file/folder.go | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/helm/Chart.yaml b/helm/Chart.yaml
index e4017805..bd433182 100644
--- a/helm/Chart.yaml
+++ b/helm/Chart.yaml
@@ -2,8 +2,8 @@ apiVersion: v2
 name: yarilo
 description: Production-grade IMAP/POP3/Submission mail server
 type: application
-version: 2.0.23
-appVersion: "2.1.17"
+version: 2.0.24
+appVersion: "2.1.18"
 keywords:
   - imap
   - submission
diff --git a/internal/storage/index/file/folder.go b/internal/storage/index/file/folder.go
index c8787f35..2b60699a 100644
--- a/internal/storage/index/file/folder.go
+++ b/internal/storage/index/file/folder.go
@@ -112,6 +112,19 @@ func (u *userIndex) OpenFolder(folder string, uidValidity uint32) (*mailbox.Fold
 // Caller holds no locks — this runs only once per session-folder.
 func (u *userIndex) loadOrInit(fs *folderState, uidValidity uint32) error {
 	st, err := os.Stat(fs.indexPath)
+	// Breadcrumb (#644/#647): unconditional, every call — not just the
+	// ErrNotExist branch — so a live repro can see the FULL stat-outcome
+	// history for a given index_path across processes (e.g. lmtp seeing it
+	// exist at t0 and imap seeing ErrNotExist at t0+1.4s for the exact same
+	// path is otherwise only inferable from the absence of a second
+	// createFresh call, not directly observed).
+	if err != nil {
+		slog.Debug("fileindex: loadOrInit stat", "folder", fs.folder,
+			"index_path", fs.indexPath, "exists", false, "err", err.Error())
+	} else {
+		slog.Debug("fileindex: loadOrInit stat", "folder", fs.folder,
+			"index_path", fs.indexPath, "exists", true, "size", st.Size(), "mod_time", st.ModTime().UnixNano())
+	}
 	switch {
 	case errors.Is(err, os.ErrNotExist):
 		return fs.createFresh(uidValidity)