From 3ea81df34fc9f334bc0c36eafd50ffc9a3656331 Mon Sep 17 00:00:00 2001
From: Peter Taoussanis <peter@taoensso.com>
Date: Wed, 3 Dec 2025 08:18:04 +0100
Subject: [PATCH] [fix] Timbre->Telemere appender: don't duplicate output
 formatting

BEFORE this commit:

  The Timbre->Telemere appender produced duplicate preamble output
  (timestamp, namespace, etc.). Both Timbre AND Telemere were adding
  preamble info.

AFTER this commit:

  Now ONLY Telemere adds preamble info.
  Timbre's `:output-fn` is ignored.
---
 main/src/taoensso/telemere/timbre.cljc | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/main/src/taoensso/telemere/timbre.cljc b/main/src/taoensso/telemere/timbre.cljc
index 1aeacc0..2ee1f2a 100644
--- a/main/src/taoensso/telemere/timbre.cljc
+++ b/main/src/taoensso/telemere/timbre.cljc
@@ -190,8 +190,11 @@
    :min-level nil
    :fn
    (fn [data]
-     (let [{:keys [instant level context ?err output_
-                   ?ns-str ?file ?line ?column]} data]
+     (let [{:keys [instant level context msg-type vargs
+                   ?ns-str ?file ?line ?column]} data
+
+           format-msg? (enc/identical-kw? msg-type :f)
+           [error msg vargs] (parse-vargs format-msg? vargs)]
 
        (taoensso.telemere/signal!
          {:kind :timbre
@@ -203,5 +206,6 @@
           :coords (when ?line [?line ?column])
           :file   ?file ; Non-standard, goes to kvs
 
-          :error  ?err
-          :msg    (force output_)})))})
+          :error        error
+          :msg          msg
+          :timbre/vargs vargs})))})