From d2eaf806c9fb863934fd073f154a002d23b21841 Mon Sep 17 00:00:00 2001
From: Leul Negash <leulnegash123456@gmail.com>
Date: Mon, 13 Jul 2026 07:48:11 +0300
Subject: [PATCH] Fix append-file concatenating without a newline (#204)

append-file appends a line but only guarantees a newline after the text,
never before it. When the file does not already end with a newline, which
is what the byte-exact write-file leaves behind, the appended line does
not start on a new line and the contents are silently merged.

Add line_separator/2 to emit a newline before appending when the file does
not already end at a line start. write-file remains byte-exact.
---
 src/skills.metta | 16 +++++++++-------
 src/skills.pl    | 10 ++++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/skills.metta b/src/skills.metta
index 355284f4..3c850a30 100644
--- a/src/skills.metta
+++ b/src/skills.metta
@@ -41,12 +41,14 @@
           WRITE-FILE-SUCCESS))
 
 (= (append-file $file $str)
-   (progn (translatePredicate (exists_file $file))
-          (translatePredicate (open $file append $Out))
-          (translatePredicate (write $Out $str))
-          (translatePredicate (nl $Out)),
-          (translatePredicate (close $Out))
-          APPEND-FILE-SUCCESS))
+   (let $sep (line_separator $file)
+        (progn (translatePredicate (exists_file $file))
+               (translatePredicate (open $file append $Out))
+               (translatePredicate (write $Out $sep))
+               (translatePredicate (write $Out $str))
+               (translatePredicate (nl $Out))
+               (translatePredicate (close $Out))
+               APPEND-FILE-SUCCESS)))
 
 (= (tavily-search $query)
    (py-call (agentverse.tavily_search $query)))
@@ -57,7 +59,7 @@
 (= (websearch $msg)
    (py-call (websearch.search $msg)))
 
-!(import_prolog_functions_from_file (library OmegaClaw-Core ./src/skills.pl) (shell first_char gc read_file_tail))
+!(import_prolog_functions_from_file (library OmegaClaw-Core ./src/skills.pl) (shell first_char gc read_file_tail line_separator))
 
 (= (metta $str)
    (let $code (sread $str)
diff --git a/src/skills.pl b/src/skills.pl
index 6afef19f..945d3c1b 100644
--- a/src/skills.pl
+++ b/src/skills.pl
@@ -54,3 +54,13 @@
         ),
         close(In)
     ).
+
+%Newline needed to start a new line at the end of Path, empty if already at one:
+line_separator(Path, Sep) :-
+    (   exists_file(Path),
+        read_file_tail(Path, 1, Tail),
+        Tail \== "",
+        Tail \== "\n"
+    ->  Sep = "\n"
+    ;   Sep = ""
+    ).